Knee prosthesis with leg length shortening

Abstract

Various implementations include a prosthetic knee device. The prosthetic knee device includes a thigh portion. The prosthetic knee device includes an upper shank portion. The thigh portion is rotatable relative to the upper shank portion. The prosthetic knee device includes a lower shank portion translationally movable relative to the upper shank portion. Rotation of the thigh portion relative to the upper shank portion causes translational movement of the lower shank portion relative to the upper shank portion.

Description

Attorney Docket Number: 09 05407 1112KNEE PROSTHESIS WITH LEG LENGTH SHORTENINGBACKGROUND

[0001] Prosthetic limbs serve millions of individuals worldwide who have experienced limb loss due to trauma, disease, or congenital conditions. Lower limb prostheses, particularly knee prostheses, present complex engineering challenges as they must replicate the sophisticated biomechanics of natural human gait while providing stability and safety' during daily activities.

[0002] Prosthesis users experience fall rates approximately twice that of the geriatric population, with many of these falls resulting in injuries or developing a fear of falling that can limit mobility' and independence. The majority of these falls occur during level or uneven terrain walking as a result of trips, slips, or problems caused by the prosthetic device itself. Research has demonstrated that trip-related falls can be substantially reduced by increasing the clearance between the foot and the ground during the syving phase of gait.SUMMARY

[0003] Various implementations include a prosthetic knee device. The prosthetic knee device includes a thigh portion. The prosthetic knee device includes an upper shank portion. The thigh portion is rotatable relative to the upper shank portion. The prosthetic knee device includes a lower shank portion translationally movable relative to the upper shank portion. Rotation of the thigh portion relative to the upper shank portion causes translational movement of the loyver shank portion relative to the upper shank portion.

[0004] In some implementations, the prosthetic knee device may further include a linkage configured to cause the translational movement of the lower shank portion relative to the upper shank portion. In some implementations, the prosthetic knee device may further include a linkage. The linkage includes an anterior link having a first end and a second end opposite and spaced apart from the first end of the anterior link. The first end of the anterior link is rotatably coupled to a first portion of the thigh portion. The second end of the anterior link is rotatably coupled to a first portion of the upper shank portion. The linkage includes a posterior link having a first end, a second end opposite and spaced apart from the first end of the posterior link, and an intermediate portion disposed between the first end of the posterior link and the second end of the posterior link. The first end of the posterior link is rotatably coupled to a second portion of the thigh portion. The intermediate portion of the posterior linkAttorney Docket Number: 09 05407 1112 is rotatably coupled to a second portion of the upper shank portion. The linkage includes a coupler link having a first end and a second end opposite and spaced apart from the first end of the coupler link. The first end of the coupler link is rotatably coupled to the second end of the posterior link. The second end of the coupler link is rotatably coupled to the lower shank portion.

[0005] In some implementations, in a first region of motion of the thigh portion relative to the upper shank portion, rotation of the thigh portion relative to the upper shank portion in a flexion direction is coupled with translational movement of the lower shank portion toward the upper shank portion. In some implementations, in a second region of motion of the thigh portion relative to the upper shank portion, compressive forces acting along an axis of translation between the upper shank portion and the lower shank portion do not cause rotation of the thigh portion relative to the upper shank portion in a flexion direction. In some implementations, the second region of motion includes full extension of the thigh portion relative to the upper shank portion. In some implementations, the second region of motion includes knee flexion angles of less than 10 degrees.

[0006] In some implementations, the thigh portion, the upper shank portion, the anterior link, and the posterior link form a four-bar linkage mechanism. In some implementations, the four-bar linkage mechanism provides an instantaneous center of rotation that moves in space as a function of a configuration of the four-bar linkage mechanism. In some implementations, when the thigh portion is in full extension relative to the upper shank portion, the instantaneous center of rotation is positioned posteriorly and superiorly relative to the upper shank portion. In some implementations, when the thigh portion is in full extension relative to the upper shank portion, the instantaneous center of rotation is positioned anteriorly and distally relative to the upper shank portion.

[0007] In some implementations, the prosthetic knee device may further include a slider link prismatically coupled to the upper shank portion. In some implementations, the prosthetic knee device may further include a slider crank mechanism. In some implementations, the slider crank mechanism includes a posterior link having a first end and a second end opposite and spaced apart from the first end of the posterior link, and an intermediate portion disposed between the first end of the posterior link and the second end of the posterior link. In some implementations, the intermediate portion of the posterior link is rotatably coupled to the upper shank portion. In some implementations, the slider crank mechanism includes a coupler link having a first end and a second end opposite and spacedAttorney Docket Number: 09 05407 1112 apart from the first end of the coupler link. In some implementations, the first end of the coupler link is rotatably coupled to the second end of the posterior link. In some implementations, the second end of the coupler link is rotatably coupled to the lower shank portion.

[0008] In some implementations, the slider crank mechanism further includes the lower shank portion which is prismatically coupled to the upper shank portion. In some implementations, the slider crank mechanism has a singular configuration in which an axis of rotation of the posterior link relative to the upper shank portion, an axis of rotation of the coupler link relative to the posterior link, and an axis of rotation of the coupler link relative to the lower shank portion are approximately connected via a straight line. In some implementations, when the slider crank mechanism is in the singular configuration, forces applied to the lower shank portion along an axis of translation of the lower shank portion relative to the upper shank portion induce no torque about the axis of rotation of the posterior link. In some implementations, the slider crank mechanism is near the singular configuration when the thigh portion is in full extension relative to the upper shank portion.

[0009] In some implementations, knee flexion is coupled to leg length retraction in a first region of knee angles corresponding to initial knee flexion and is coupled to leg length extension in a third region of knee angles corresponding to large knee flexion angles.

[0010] In some implementations, the prosthetic knee device may further include a damping mechanism that is kinematically coupled to the motion of the thigh portion relative to the upper shank portion. In some implementations, the damping mechanism includes a pneumatic actuator, a hydraulic actuator, a friction swing control unit, or a magnetorheological damper. In some implementations, the prosthetic knee device may further include an extension spring that is kinematically coupled to the motion of the thigh portion relative to the upper shank portion.

[0011] In some implementations, the lower shank portion is configured to be coupled to a prosthetic foot. In some implementations, the thigh portion is configured to be coupled to a prosthetic socket for attachment to a residual limb.BRIEF DESCRIPTION OF DRAWINGS

[0012] Example features and implementations of the present disclosure are disclosed in the accompanying drawings. However, the present disclosure is not limited to the preciseAttorney Docket Number: 09 05407 1112 arrangements and instrumentalities shown. Similar elements in different implementations are designated using the same reference numerals.

[0013] FIG. 1 is a schematic view of a prosthetic knee mechanism with nonbackdrivable coupling, according to one implementation.

[0014] FIG. 2 is a schematic view of a prosthetic knee mechanism with slider crank coupling, according to another implementation.

[0015] FIG. 3 is a schematic view of a prosthetic knee mechanism with clutch mechanism, according to another implementation.

[0016] FIGS. 4A and 4C are schematic views showing slider crank mechanism configurations near singular positions. FIG. 4B is a schematic view showing a slider crank mechanism configuration at a singular position.

[0017] FIG. 5 is a schematic view of a prior art four bar linkage coupling.

[0018] FIG. 6 is a schematic view of a prosthetic knee mechanism with four bar linkage and slider crank mechanism, according to one implementation.

[0019] FIG. 7 is a side view of a prosthetic knee mechanism with four bar linkage coupling, according to one implementation.

[0020] FIG. 8 is a side view of the prosthetic knee mechanism shown in FIG. 7 during early stance phase.

[0021] FIG. 9 is a side view of the prosthetic knee mechanism shown in FIG. 7 during late stance phase.

[0022] FIGS. 10A-10E are side views of the prosthetic knee mechanism shown in FIG. 5 at different flexion angles.

[0023] FIG. 11 is a graph showing leg length retraction versus knee flexion angle.

[0024] FIG. 12 is a graph showing simulated foot clearance w ith and without retraction.

[0025] FIGS. 13A-13F are side views of a prosthetic knee mechanism with progressive flexion configurations, according to another implementation.

[0026] FIG. 14 is a perspective view of the prosthetic knee mechanism shown in FIGS. 13A-13F.

[0027] FIG. 15 is a top view of the prosthetic knee mechanism shown in FIGS. 13A- 13F.

[0028] FIG. 16 is a bottom view of the prosthetic knee mechanism shown in FIGS. 13A-13F.Attorney Docket Number: 09 05407 1112

[0029] FIG. 17 is a front view of the prosthetic knee mechanism shown in FIGS. 13A- 13F.

[0030] FIG. 18 is a rear view of the prosthetic knee mechanism shown in FIGS. 13A- 13F.DETAILED DESCRIPTION

[0031] The devices, systems, and methods disclosed herein provide for prosthetic knee devices comprising a thigh portion, an upper shank portion, and a lower shank portion. The thigh portion is rotatable relative to the upper shank portion, and the lower shank portion is translationally movable relative to the upper shank portion. Rotation of the thigh portion relative to the upper shank portion causes translational movement of the lower shank portion relative to the upper shank portion. This mechanical coupling enables the prosthetic knee device to shorten the leg length during swing phase when the knee flexes, thereby increasing clearance between the foot and ground. During stance phase when the knee is extended, the leg maintains its full length to allow" for proper stance phase functionality.

[0032] The coupling between knee rotation and leg length adjustment for the devices, systems, and methods disclosed herein is achieved through various mechanical linkage systems. In some implementations, a four-bar linkage mechanism couples the thigh portion to the upper shank portion, providing controlled rotation with a moving instantaneous center of rotation. In some implementations, a slider crank mechanism enables the translational movement of the low er shank portion relative to the upper shank portion. The slider crank mechanism can include a posterior link, a coupler link, and the lower shank portion which functions as a slider link that is prismatically coupled to the upper shank portion. The posterior link of the four-bar linkage can be mechanically coupled to the slider crank mechanism, creating a kinematic chain that translates knee flexion into leg length retraction.

[0033] The prosthetic knee devices disclosed herein operate in different regions of motion to provide both swing phase functionality and stance phase stability. In a first region of motion corresponding to initial knee flexion, rotation of the thigh portion in the flexion direction is coupled w ith translational movement of the lower shank portion toward the upper shank portion, resulting in leg length retraction. In a second region of motion that includes full extension of the thigh portion relative to the upper shank portion, compressive forces acting along the axis of translation between the upper and lower shank portions do not cause rotation of the thigh portion in the flexion direction. This configuration prevents the knee fromAttorney Docket Number: 09 05407 1112 buckling under body weight during stance phase while maintaining the coupling functionality during swing phase.

[0034] In some implementations, the coupling between knee rotation and leg length adjustment may be achieved using a nonbackdrivable mechanism. The nonbackdrivable mechanism includes a driving input coupled to the rotation of the thigh portion relative to the upper shank portion and a driven output coupled to the translational motion of the lower shank portion relative to the upper shank portion. In such implementations, forces or torques exerted on the driving input can induce motion at the driven output, but forces or torques exerted on the driven output do not induce motion at the driven input. The nonbackdrivable mechanism may be implemented using worm gears, bidirectional overrunning clutches, or lead screws.

[0035] In some implementations, a clutch mechanism may be included to selectively engage and disengage the coupling between knee rotation and leg length adjustment. When the knee is in a sufficiently extended orientation, the clutch engages to prevent relative translational motion between the upper shank portion and the lower shank portion. The clutch may be implemented using a positive engagement clutch, friction clutch, hydraulic clutch, magnetic clutch, or latch mechanism. The engagement and disengagement of the clutch may be driven by actuators such as motors or solenoids and controlled by microcomputers in conjunction with sensors, or alternatively driven by a mechanism that is coupled to the knee orientation.

[0036] In some implementations, the coupling between knee rotation and leg translation may be achieved using various mechanical systems including linkage-based mechanisms, rack and pinion systems, cable drives, traction drives, or other power transmission components. The prosthetic knee device may be paired with swing or stance control mechanisms including pneumatic actuators, hydraulic actuators, friction swing control units, magnetorheological dampers, or extension springs. These additional mechanisms may be located between various components, such as a linear damper or extension spring located within the translational coupling between the upper and lower shank portions.

[0037] Various implementations include a prosthetic knee device. The prosthetic knee device includes a thigh portion. The prosthetic knee device includes an upper shank portion. The thigh portion is rotatable relative to the upper shank portion. The prosthetic knee device includes a lower shank portion translationally movable relative to the upper shank portion. Rotation of the thigh portion relative to the upper shank portion causes translational movement of the lower shank portion relative to the upper shank portion.Attorney Docket Number: 09 05407 1112

[0038] As shown in FIGS. 1-4, 6-10E, and 13A-18, the prosthetic knee devices 100 disclosed herein comprise a thigh portion 110, an upper shank portion 120, and a lower shank portion 130 that work together to provide both rotational and translational movement capabilities. The thigh portion 110 forms the proximal component of the prosthetic knee device 100 and provides the primary' attachment interface for connection to the user's residual limb. The thigh portion 110 includes structural elements configured to withstand the forces and moments transmitted during walking and other activities of daily living. In some implementations, the thigh portion 110 may be configured to be coupled to a prosthetic socket for attachment to a residual limb, providing a secure and comfortable interface between the prosthetic device 100 and the user's anatomy.

[0039] The upper shank portion 120 forms the intermediate component of the prosthetic knee device 100 and serves as the central structural element that interfaces with both the thigh portion 110 and the lower shank portion 130. The thigh portion 110 is rotatable relative to the upper shank portion 120, enabling the knee flexion and extension motions that are fundamental to normal gait patterns. This rotational relationship between the thigh portion 110 and upper shank portion 120 replicates the primary degree of freedom found in biological knee joints. The upper shank portion 120 includes mounting features and structural elements that accommodate the mechanical linkages and coupling mechanisms that coordinate the movement between the rotational and translational degrees of freedom.

[0040] The lower shank portion 130 forms the distal component of the prosthetic knee device 100 and provides the connection interface to the prosthetic foot assembly. The lower shank portion 130 is translationally movable relative to the upper shank portion 120, enabling the leg length adjustment functionality that distinguishes this prosthetic knee device 100 from conventional designs. This translational movement capability allows the lower shank portion 130 to move proximally and distally relative to the upper shank portion 120 along a defined axis of translation 126. In some implementations, the low er shank portion 130 may be configured to be coupled to a prosthetic foot, providing the complete lower limb prosthetic assembly.

[0041] The fundamental operating principle of the prosthetic knee device 100 centers on the mechanical coupling between these two primary degrees of freedom. Rotation of the thigh portion 110 relative to the upper shank portion 120 causes translational movement of the lower shank portion 130 relative to the upper shank portion 120. This coupling relationship enables the prosthetic knee device 100 to automatically adjust leg length in response to kneeAttorney Docket Number: 09 05407 1112 flexion and extension motions. The coupling mechanism coordinates these movements such that knee flexion during swing phase results in leg length shortening, while knee extension during stance phase maintains full leg length for proper ground contact and stability.

[0042] In some implementations, the structural configuration of these components may vary7to accommodate different user requirements and design specifications. The thigh portion 110 may include adjustable mounting features to accommodate different residual limb geometries and attachment preferences. The upper shank portion 120 may incorporate different materials and cross-sectional geometries to optimize strength, weight, and durability characteristics. The lower shank portion 130 may include various interface configurations to accommodate different prosthetic foot designs and attachment methods. The translational movement capability of the lower shank portion 130 relative to the upper shank portion 120 may be implemented through different mechanical arrangements, including sliding interfaces, telescoping structures, or other linear motion mechanisms.

[0043] FIGS. 5 and 6 show a four-bar linkage mechanism 140 of a prosthetic knee device 100 according to one implementation. The four-bar linkage mechanism 140 provides the rotational coupling between the thigh portion 110 and the upper shank portion 120. The four-bar linkage mechanism 140 comprises the thigh portion 110, the upper shank portion 120, an anterior link 150, and a posterior link 160 that w ork together to create a controlled rotational joint with enhanced functionality compared to simple hinge joints. The anterior link 150 has a first end 153 and a second end 154 opposite and spaced apart from the first end 153 of the anterior link 150. The first end 153 of the anterior link 150 is rotatably coupled to a first portion 112 of the thigh portion 110, while the second end 154 of the anterior link 150 is rotatably coupled to a first portion 122 of the upper shank portion 120. This rotational coupling allows the anterior link 150 to pivot relative to both the thigh portion 110 and the upper shank portion 120 during knee flexion and extension motions.

[0044] The posterior link 160 has a first end 162, a second end 164 opposite and spaced apart from the first end 162 of the posterior link 160, and an intermediate portion 166 disposed between the first end 162 of the posterior link 160 and the second end 164 of the posterior link 160. The first end 162 of the posterior link 160 is rotatably coupled to a second portion 1 14 of the thigh portion 110, creating a pivot connection that allows rotational movement between the posterior link 160 and the thigh portion 110. The intermediate portion 166 of the posterior link 160 is rotatably coupled to a second portion 124 of the upper shank portion 120, establishing the rotational interface between the posterior link 160 and the upperAttorney Docket Number: 09 05407 1112 shank portion 120. This configuration creates a kinematic chain where the thigh portion 110 and upper shank portion 120 are connected through two parallel links, forming the characteristic four-bar linkage geometry.

[0045] With continued reference to FIGS. 5 and 6, the four-bar linkage mechanism 140 provides an instantaneous center of rotation 106 that moves in space as a function of a configuration of the four-bar linkage mechanism 140. Unlike simple hinge joints that rotate about a fixed center, the four-bar linkage mechanism 140 creates a moving instantaneous center of rotation 106 that changes position as the knee flexes and extends. This moving center of rotation 106 enables the prosthetic knee device 100 to replicate more closely the complex motion patterns found in biological knee joints, where the center of rotation shifts during different phases of knee movement. The position of the instantaneous center of rotation 106 depends on the relative lengths and orientations of the anterior link 150 and posterior link 160, as well as the current angular configuration of the four-bar linkage mechanism 140.

[0046] Referring to FIG. 6, the linkage mechanism extends beyond the basic four-bar configuration to include additional coupling elements that connect the rotational motion to the translational movement of the lower shank portion 130. A coupler link 170 has a first end 172 and a second end 174 opposite and spaced apart from the first end 172 of the coupler link 170. The first end 172 of the coupler link 170 is rotatably coupled to the second end 164 of the posterior link 160, creating a mechanical connection that transfers motion from the four-bar linkage mechanism 140 to the translational system. The second end 174 of the coupler link 170 is rotatably coupled to the lower shank portion 130, establishing the kinematic link between the rotational motion of the knee joint and the translational motion of the lower shank portion 130 relative to the upper shank portion 120. This coupling arrangement creates a unified mechanical system where knee flexion and extension directly drive the leg length adjustment mechanism.

[0047] As further shown in FIG. 6, the structural arrangement of the linkage components creates multiple rotational interfaces that coordinate the movement between different portions of the prosthetic knee device 100. The rotational couplings between the various links allow each component to pivot relative to adjacent components while maintaining the overall kinematic relationships that govern the device operation. The spacing and positioning of the rotational coupling points determine the mechanical advantage and motion characteristics of the linkage system. The geometric relationships between the link lengths and pivot locations control how the rotational motion of the thigh portion 110 relative to the upperAttorney Docket Number: 09 05407 1112 shank portion 120 translates into the desired translational movement of the lower shank portion 130.

[0048] FIG. 7 shows an implementation of a prosthetic knee device 100 including the linkage mechanism shown in FIG. 6. The complete linkage system demonstrates how the four- bar mechanism 140 integrates with the translational coupling to create a coordinated movement system. The positioning of the instantaneous center of rotation 106 varies depending on the specific configuration and angular position of the four-bar linkage mechanism 140. When the thigh portion 1 10 is in full extension relative to the upper shank portion 120, the instantaneous center of rotation 106 may be positioned posteriorly and superiorly relative to the upper shank portion 120. providing stance phase stability characteristics. In some implementations, when the thigh portion 110 is in full extension relative to the upper shank portion 120, the instantaneous center of rotation 106 may be positioned anteriorly and distally relative to the upper shank portion 120, depending on the specific link geometry and design parameters selected for the four-bar linkage mechanism 140.

[0049] In some implementations, the coupling between knee rotation and leg translation may be achieved using various alternative mechanical systems beyond the four-bar linkage configuration. Linkage-based mechanisms may include different multi-bar configurations, such as five-bar or six-bar linkages that provide additional degrees of freedom or motion characteristics. Rack and pinion systems may provide direct conversion between rotational and linear motion through gear-based interfaces. Cable drives may use flexible cables and pulleys to transmit motion between the rotational and translational components, allowing for more complex routing of the mechanical connections. Traction drives may employ friction-based power transmission elements to couple the rotational and translational motions. Other power transmission components may include belt drives, chain drives, or cambased mechanisms that provide alternative methods for coordinating the knee rotation with leg length adjustment.

[0050] In some implementations, the thigh portion 110 may be coupled to the upper shank portion 120 via joints with either fixed center of rotation or moving center of rotation configurations. Fixed center of rotation joints, such as simple hinge mechanisms, provide rotational motion about a stationary pivot point that does not change position during knee flexion and extension. Moving center of rotation joints, such as four-bar knee joints, polycentric mechanisms, or other multi-link configurations, provide rotational motion about an instantaneous center 106 that shifts position as the joint moves through its range of motion.Attorney Docket Number: 09 05407 1112The selection between fixed and moving center configurations depends on the desired motion characteristics, stability requirements, and functional objectives of the prosthetic knee device 100. Moving center configurations may provide enhanced biomechanical compatibility and improved stance phase stability characteristics compared to fixed center alternatives.

[0051] Referring to FIG. 2, the slider crank mechanism 180 provides the mechanical coupling that converts rotational motion of the knee joint into translational movement of the lower shank portion 130 relative to the upper shank portion 120. The slider crank mechanism 180 comprises a posterior link 160, a coupler link 170, and the lower shank portion 130 which functions as a slider link within the kinematic chain. As with the implementation shown in FIGS. 5-7, the posterior link 160 has a first end 162 and a second end 164 opposite and spaced apart from the first end 162 of the posterior link 160, and an intermediate portion 166 disposed between the first end 162 of the posterior link 160 and the second end 164 of the posterior link 160. The intermediate portion 166 of the posterior link 160 is rotatably coupled to the upper shank portion 120, creating a pivot connection that allows the posterior link 160 to rotate relative to the upper shank portion 120 as the knee flexes and extends. This rotational coupling serves as the driving input for the slider crank mechanism 180, where knee motion generates the rotational movement of the posterior link 160 that drives the subsequent translational motion.

[0052] The coupler link 170 has a first end 172 and a second end 174 opposite and spaced apart from the first end 172 of the coupler link 170, establishing the intermediate connection within the slider crank mechanism 180. The first end 172 of the coupler link 170 is rotatably coupled to the second end 164 of the posterior link 160, creating a pivotal connection that transfers motion from the rotating posterior link 160 to the coupler link 170. The second end 174 of the coupler link 170 is rotatably coupled to the lower shank portion 130, completing the kinematic chain that converts the rotational motion of the posterior link 160 into the translational movement of the low er shank portion 130. As the posterior link 160 rotates about the intermediate portion 166, the coupler link 170 follow s a complex motion path that combines both rotational and translational components, ultimately driving the lower shank portion 130 to translate relative to the upper shank portion 120.

[0053] With continued reference to FIG. 2, the lower shank portion 130 functions as the slider component within the slider crank mechanism 180 and is prismatically coupled to the upper shank portion 120. The prismatic coupling constrains the lower shank portion 130 to move only along a defined axis of translation 126 relative to the upper shank portion 120,Attorney Docket Number: 09 05407 1112 preventing rotational movement while allowing the linear motion that creates the leg length adjustment functionality. The prismatic joint may be implemented through various mechanical arrangements, including sliding bearings, linear guides, or telescoping structures that provide smooth translational movement while maintaining structural alignment between the upper shank portion 120 and lower shank portion 130. The combination of the rotational coupling of the coupler link 170 to the lower shank portion 130 and the prismatic coupling of the lower shank portion 130 to the upper shank portion 120 creates the kinematic constraint that converts the complex motion of the coupler link 170 into pure translational movement of the lower shank portion 130.

[0054] Referring to FIGS. 4A-4C and 6, the slider crank mechanism 180 has a singular configuration that plays a role in the stability characteristics of the prosthetic knee device 100 during different phases of gait. The singular configuration occurs when an axis of rotation of the intermediate portion 166 of the posterior link 160 relative to the second portion 124 of the upper shank portion 120, an axis of rotation of the first end 172 of the coupler link 170 relative to the second end 164 of the posterior link 160, and an axis of rotation of the second end 174 of the coupler link 170 relative to the lower shank portion 130 are approximately connected via a straight line. In this geometric arrangement, the three rotational axes become collinear, creating a specific kinematic condition where the mechanical advantage of the slider crank mechanism 180 approaches infinity. The singular configuration represents a transition point in the operation of the slider crank mechanism 180 where the relationship between input rotation and output translation changes dramatically.

[0055] When the slider crank mechanism 180 is in the singular configuration, forces applied to the lower shank portion 130 along an axis of translation 126 of the lower shank portion 130 relative to the upper shank portion 120 induce no torque about the axis of rotation of the posterior link 160. This characteristic provides stability benefits during stance phase when the prosthetic knee device 100 experiences compressive forces from body weight and ground reaction forces 108. As shown in FIG. 4B, the collinear arrangement of the rotational axes prevents translational forces on the lower shank portion 130 from generating rotational moments that could cause unwanted knee flexion. The singular configuration effectively decouples the translational forces from the rotational motion, allowing the prosthetic knee device 100 to support body weight without compromising knee stability .

[0056] As further shown in FIGS. 4A and 4C, when the slider crank mechanism 180 is near the singular configuration shown in FIG. 4B. forces applied to the lower shank portionAttorney Docket Number: 09 05407 1112130 generate small torques 116 about the axis of rotation of the posterior link 160. The magnitude of these torques 116 depends on how close the mechanism is to the exact singular configuration, with smaller deviations from collinearity producing smaller torques 116. The direction of the generated torque 116 depends on which side of the singular configuration the mechanism occupies, with forces producing torques 116 in opposite directions on either side of the singular position. This characteristic allows the prosthetic knee device 100 to provide controlled resistance to unwanted knee motion while maintaining the coupling functionality during appropriate phases of gait.

[0057] The slider crank mechanism 180 is near the singular configuration when the thigh portion 110 is in full extension relative to the upper shank portion 120, corresponding to the stance phase position where knee stability is most important. During this phase of gait, the near-singular configuration minimizes the transmission of compressive forces from the lower shank portion 130 to rotational torques 116 about the knee joint, preventing knee buckling under body weight. The geometric relationships of the slider crank mechanism 180 are designed such that the approach to the singular configuration coincides with the knee extension angles where stance phase stability is required. As the knee begins to flex from the fully extended position, the slider crank mechanism 180 moves away from the singular configuration, allowing the coupling between knee rotation and leg length adjustment to become active during swing phase.

[0058] In some implementations, the slider link may be implemented as a separate component that is prismatically coupled to the upper shank portion 120 rather than using the lower shank portion 130 directly as the slider element. The separate slider link may provide additional design flexibility in terms of materials, cross-sectional geometry, and interface characteristics while maintaining the same kinematic functionality. The slider link may incorporate bearing surfaces, sealing elements, or other features that enhance the performance and durability of the translational coupling. The connection between the slider link and the lower shank portion 130 may be rigid or may include additional mechanical elements that provide specific force transmission or motion characteristics.

[0059] In some implementations, the singular configuration characteristics may be adjusted through modifications to the link lengths, pivot locations, or geometric relationships within the slider crank mechanism 180. The proximity to the singular configuration during different knee angles may be tuned to optimize the balance between coupling functionality and stability characteristics. The transition behavior as the mechanism moves through and awayAttorney Docket Number: 09 05407 1112 from the singular configuration may be controlled through the selection of specific geometric parameters that govern the kinematic relationships. Alternative slider crank configurations may employ different link arrangements or additional mechanical elements that modify the singular configuration behavior while maintaining the fundamental coupling between rotational and translational motion.

[0060] FIG. 1 demonstrates how anonbackdrivable mechanism 190 can be incorporated into some implementations of a prosthetic knee device 100. The nonbackdrivable mechanism 190 provides an alternative approach for coupling knee rotation to leg length adjustment that addresses the stability concerns associated with bidirectional mechanical coupling. The nonbackdrivable mechanism 190 comprises a driving input and a driven output that are mechanically connected through an internal mechanism that permits motion transmission in only one direction. The driving input of the nonbackdrivable mechanism 190 is coupled to the rotation of the thigh portion 110 relative to the upper shank portion 120. while the driven output is coupled to the translational motion of the lower shank portion 130 relative to the upper shank portion 120. This unidirectional coupling arrangement allows knee flexion motions to drive leg length retraction during swing phase while preventing compressive forces on the leg from inducing knee flexion torques during stance phase.

[0061] The operational characteristics of the nonbackdrivable mechanism 190 center on the directional transmission properties that distinguish the driving input from the driven output. Forces or torques applied to the driving input can induce corresponding motion at the driven output through the internal mechanism, enabling knee flexion to generate the desired leg length shortening during swing phase. However, forces or torques applied to the driven output do not induce motion at the driving input due to the nonbackdrivable characteristics of the internal mechanism. This asymmetric behavior prevents ground reaction forces 108 and body weight loads that act on the lower shank portion 130 from generating torques about the knee joint that could cause unwanted knee buckling during stance phase. The nonbackdrivable mechanism 190 effectively decouples the reverse load path while maintaining the forward motion coupling that provides the swing phase functionality.

[0062] As further shown in FIG. 1, the mechanical connection between the driving input and driven output incorporates internal components that create the nonbackdrivable characteristics through specific geometric relationships and contact conditions. The internal mechanism may include gear trains, threaded interfaces, or clutch assemblies that permit motion transmission when driven from the input side while resisting motion transmission whenAttorney Docket Number: 09 05407 1112 forces are applied to the output side. The mechanical advantage and motion scaling between the driving input and driven output depend on the specific configuration of the internal mechanism components. The nonbackdrivable mechanism 190 may also incorporate additional elements such as springs, dampers, or friction devices that modify the transmission characteristics or provide supplementary functionality during different phases of operation.

[0063] In some implementations, the nonbackdrivable mechanism 190 may be implemented using worm gears that provide the unidirectional transmission characteristics through the geometric relationship between the worm and worm wheel components. Worm gear systems exhibit natural nonbackdrivable behavior when the lead angle of the worm threads falls below the friction angle of the gear interface, preventing the worm wheel from driving the worm in reverse. The worm component may be coupled to the knee rotation through direct connection to the thigh portion 110 or through intermediate linkages that transfer the rotational motion. The worm wheel component may be coupled to the leg length adjustment mechanism through connections to the translational coupling between the upper shank portion 120 and lower shank portion 130. The gear ratio between the worm and worm wheel determines the mechanical advantage and motion scaling between knee rotation and leg length adjustment.

[0064] In some implementations, the nonbackdrivable mechanism 190 may be implemented using bidirectional overrunning clutches that selectively engage and disengage based on the direction of applied torque or motion. Bidirectional overrunning clutches incorporate internal elements such as sprags, rollers, or pawls that engage with raceways or cam surfaces to transmit torque in one direction while freewheeling in the opposite direction. The clutch assembly may be configured to disengage when knee flexion torques are applied to the driving input, allowing the transmission of motion to the leg length adjustment mechanism. When compressive forces on the leg attempt to drive motion in the reverse direction, the clutch engages and prevents the transmission of forces back to the knee joint. The engagement and disengagement characteristics of the bidirectional overrunning clutch may be tuned through the selection of specific internal components and geometric parameters.

[0065] In some implementations, the nonbackdrivable mechanism 190 may be implemented using lead screws that convert rotational motion to linear motion while providing inherent resistance to backdriving through thread friction. Lead screw assemblies comprise a threaded shaft and a mating nut that translates along the shaft as the shaft rotates, with the thread pitch determining the linear displacement per revolution. The lead screw shaft may beAttorney Docket Number: 09 05407 1112 coupled to the knee rotation through direct or indirect mechanical connections, while the translating nut may be coupled to the lower shank portion 130 to provide the leg length adjustment motion. The thread geometry and surface finish of the lead screw components determine the efficiency of forw ard motion transmission and the resistance to backdriving. Fine thread pitches and appropriate material selections may enhance the nonbackdrivable characteristics by increasing the friction forces that resist reverse motion transmission.

[0066] FIG. 3 demonstrates how a clutch mechanism 192 can be incorporated into some implementations of a prosthetic knee device 100. The clutch mechanism 192 provides selective control over the coupling between knee rotation and leg length adjustment by engaging and disengaging the translational motion between the upper shank portion 120 and the lower shank portion 130. The clutch mechanism 192 shown in FIG. 3 comprises a positive engagement pin 194 that interfaces with corresponding engagement features 196 to prevent or allow relative motion between the upper shank portion 120 and lower shank portion 130. When the clutch mechanism 192 is engaged, the positive engagement pin 194 locks the upper shank portion 120 and lower shank portion 130 together, preventing translational movement and effectively decoupling the knee rotation from leg length adjustment. When the clutch mechanism 192 is disengaged, the positive engagement pin 194 withdraws from the engagement features 196, allowing the translational coupling to operate and enabling knee flexion to drive leg length retraction during swing phase.

[0067] The operational sequence of the clutch mechanism 192 coordinates with the gait cycle to provide stance phase stability while maintaining swing phase functionality. When the knee is in a sufficiently extended orientation corresponding to stance phase, the clutch mechanism 192 engages to prevent relative translational motion between the upper shank portion 120 and lower shank portion 130. This engagement eliminates the mechanical coupling that would otherwise allow compressive forces acting on the lower shank portion 130 to generate flexion torques about the knee joint. During stance phase, ground reaction forces 108 and body w eight loads act along the axis of translation 126 betw een the upper shank portion 120 and lower shank portion 130, but the engaged clutch mechanism 192 prevents these forces from inducing unwanted knee motion. As the knee transitions from stance phase to swing phase and begins to flex, the clutch mechanism 192 disengages to restore the coupling between knee rotation and leg length adjustment.

[0068] With continued reference to FIG. 3, the positive engagement clutch mechanism 192 operates through direct mechanical contact between mating surfaces that lock theAttorney Docket Number: 09 05407 1112 translational degree of freedom when engaged. The positive engagement pin 194 moves between engaged and disengaged positions through actuation mechanisms that control the timing and force characteristics of the engagement process. The engagement features 196 may comprise slots, grooves, or other geometric configurations that receive the positive engagement pin 194 and provide secure mechanical connection when the clutch is activated. The disengagement process involves withdrawing the positive engagement pin 194 from the engagement features 196, allowing the upper shank portion 120 and lower shank portion 130 to resume translational movement relative to each other. The positive engagement design provides definitive locking characteristics with minimal backlash or compliance when engaged, while offering clear disengagement when the coupling functionality is desired.

[0069] In some implementations, the clutch mechanism 192 may be implemented using friction clutch configurations that engage and disengage through controlled friction forces between mating surfaces. Friction clutch mechanisms may comprise disc assemblies, cone clutches, or band brake configurations that generate clamping forces to prevent relative motion between the upper shank portion 120 and lower shank portion 130. The friction clutch may incorporate multiple friction surfaces to increase the torque capacity and provide smooth engagement characteristics. The friction materials may be selected to provide appropriate coefficient of friction values and wear resistance for the operating conditions encountered during prosthetic use. The clamping force applied to the friction surfaces may be controlled through mechanical, hydraulic, or pneumatic actuation systems that modulate the engagement characteristics based on the desired operational requirements.

[0070] In some implementations, the clutch mechanism 192 may be implemented using hydraulic clutch systems that utilize fluid pressure to control the engagement and disengagement process. Hydraulic clutch mechanisms may comprise piston assemblies, valve systems, and fluid reservoirs that generate and control the hydraulic forces used to operate the clutch. The hydraulic system may provide variable engagement force characteristics that allow for gradual engagement and disengagement rather than abrupt on-off operation. The hydraulic fluid may be contained within sealed chambers that prevent contamination and maintain consistent operating characteristics over extended periods of use. The hydraulic clutch system may incorporate pressure relief valves, accumulators, or other components that provide safety features and performance optimization during different operating conditions.

[0071] In some implementations, the clutch mechanism 192 may be implemented using magnetic clutch configurations that utilize electromagnetic or permanent magnet forces toAttorney Docket Number: 09 05407 1112 control the engagement process. Magnetic clutch mechanisms may comprise electromagnet assemblies that generate magnetic fields to attract ferromagnetic components and create the engagement forces. The electromagnetic clutch may be controlled through electrical cunent supplied to the electromagnet windings, allowing for precise control of the engagement timing and force characteristics. Permanent magnet clutch configurations may utilize permanent magnets in combination with movable magnetic circuit elements that control the magnetic flux path to engage and disengage the clutch. The magnetic clutch design may provide non-contact operation that reduces wear and maintenance requirements compared to mechanical contact clutches.

[0072] In some implementations, the clutch mechanism 192 may be implemented using latch mechanisms that provide mechanical engagement through spring-loaded or cam-actuated components. Latch mechanisms may comprise spring-loaded pins, balls, or other engagement elements that automatically engage when the upper shank portion 120 and lower shank portion 130 reach specific relative positions. The latch mechanism may incorporate cam surfaces or ramp features that facilitate smooth engagement and disengagement as the components move through their operating range. The spring forces within the latch mechanism may be selected to provide appropriate engagement force while allowing for reliable disengagement when the coupling functionality is desired. The latch mechanism may include manual override features that allow for emergency disengagement or maintenance access when required.

[0073] The engagement and disengagement of the clutch mechanism 192 may be driven by actuators such as motors or solenoids that provide controlled motion to operate the clutch components. Motor-driven actuators may comprise electric motors with gear reduction systems that provide the torque and positioning accuracy required for clutch operation. The motor actuators may incorporate position feedback systems such as encoders or potentiometers that provide closed-loop control of the clutch position. Solenoid actuators may provide rapid engagement and disengagement through electromagnetic force generation that moves the clutch components between engaged and disengaged positions. The solenoid actuators may be designed for either push or pull operation depending on the specific clutch mechanism configuration and the desired fail-safe characteristics.

[0074] The control of the clutch engagement and disengagement may be accomplished through microcomputers in conjunction with sensors that monitor the prosthetic knee device 100 operating conditions and gait phase. The microcomputer may execute control algorithms that determine the appropriate timing for clutch engagement and disengagement based onAttorney Docket Number: 09 05407 1112 sensor inputs such as knee angle, ground contact forces, or acceleration measurements. The sensor systems may comprise angle sensors that monitor the rotational position of the thigh portion 1 10 relative to the upper shank portion 120, load sensors that detect ground reaction forces 108 or body weight loading, and inertial sensors that measure acceleration or angular velocity' during different phases of gait. The microcomputer may process the sensor data in real-time to predict gait phase transitions and control the clutch mechanism 192 accordingly to optimize both stance phase stability and swing phase functionality.

[0075] In some implementations, the engagement and disengagement of the clutch mechanism 192 may be driven by mechanical systems that are coupled to the knee orientation rather than electronic control systems. Mechanical control systems may utilize cam mechanisms, linkage assemblies, or spring-loaded components that automatically engage and disengage the clutch based on the angular position of the knee joint. The mechanical control system may comprise cam followers that track cam profiles attached to the rotating components of the knee joint, with the cam profile geometry determining the clutch engagement timing as a function of knee angle. Linkage-based control systems may utilize additional mechanical links that connect the clutch actuator to the knee joint components, providing direct mechanical coupling between knee position and clutch operation. Spring- loaded control mechanisms may utilize compression or extension springs that store and release energy based on the knee joint configuration, providing automatic clutch operation without external power sources or electronic control systems.

[0076] Referring to FIG. 1 1 , the prosthetic knee device 100 operates through distinct regions of motion that define the relationship between knee flexion angle and leg length adjustment. The graph demonstrates that the coupling between knee rotation and leg length retraction varies significantly across different angular ranges of knee motion. As an example, for the implementation used for the graph shown in FIG. 11, the first region of motion occurs when the knee is flexed between approximately 5 and 60 degrees, where rotation of the thigh portion 110 relative to the upper shank portion 120 in a flexion direction is coupled with translational movement of the lower shank portion 130 toward the upper shank portion 120. During this first region, increasing knee flexion produces progressive leg length retraction, with the maximum retraction occurring at approximately 60 degrees of knee flexion as shown in the plotted relationship. In some implementations, the first region of motion occurs when the knee is flexed between approximately 5 and 90 degrees.Attorney Docket Number: 09 05407 1112

[0077] The second region of motion for the example implementation shown in FIG. 11 encompasses knee flexion angles of less than 10 degrees and includes full extension of the thigh portion 1 10 relative to the upper shank portion 120. Within this second region, compressive forces acting along an axis of translation 126 between the upper shank portion 120 and the lower shank portion 130 do not cause rotation of the thigh portion 110 relative to the upper shank portion 120 in a flexion direction. The slider crank mechanism 180 approaches its singular configuration when the knee is at angles less than 10 degrees of flexion, creating the mechanical condition where translational forces cannot generate significant rotational torques about the knee joint. This characteristic provides stance phase stability by preventing ground reaction forces 108 and body weight from inducing unwanted knee flexion when the prosthetic knee device 100 supports the user during walking.

[0078] As further shown in FIG. 11 , the coupling relationship inverts after peak leg length retraction occurs, creating a third region of knee angles corresponding to large knee flexion angles where knee flexion is coupled to leg length extension rather than retraction. The transition from retraction to extension occurs at the peak retraction point around 60 degrees of knee flexion, after which continued knee flexion produces leg length extension back toward the original extended length. This inversion corresponds to a second singular configuration of the mechanical linkage system where the kinematic relationships change direction. The third region extends from approximately 60 degrees of knee flexion through the full range of knee motion, encompassing the large flexion angles encountered during activities such as sitting or deep knee bends.

[0079] The inverted coupling relationship in the third region provides functional benefits during activities that require large knee flexion angles. When knee flexion angle is large, the coupling to leg length extension allows the prosthetic knee device 100 to maintain appropriate leg length proportions during sitting positions, where leg length retraction would create undesirable cosmetic appearance or functional limitations. During sit-to-stand transitions, the coupling between compressive forces on the leg and knee extension assists the user in straightening the leg, as ground reaction forces 108 applied to the lower shank portion 130 help drive knee extension through the mechanical linkage system. The extension of leg length during large knee flexion angles also prevents the lower shank portion 130 from retracting excessively during activities that require significant knee bending.

[0080] In some implementations, the angular ranges that define the different regions of motion may be adjusted through modifications to the linkage geometry, pivot locations, orAttorney Docket Number: 09 05407 1112 mechanical advantage ratios within the coupling mechanism. The transition points between regions may be shifted to optimize the coupling characteristics for specific user requirements or gait patterns. The magnitude of leg length retraction achieved during the first region may be controlled through the selection of link lengths and geometric relationships within the slider crank mechanism 180. The slope of the coupling relationship within each region may be modified to provide different rates of leg length change per degree of knee flexion, allowing for customization of the swing phase clearance characteristics and stance phase stability behavior.

[0081] In some implementations, the coupling characteristics may incorporate additional mechanical elements that modify the relationship between knee flexion and leg length adjustment. Spring elements may be integrated into the linkage system to provide bias forces that influence the coupling behavior or provide return forces that assist in leg length extension. Damping elements may be incorporated to control the rate of leg length change and provide smooth transitions betw een different regions of motion. Variable mechanical advantage systems may be employed to create non-linear coupling relationships that optimize the leg length adjustment characteristics for different phases of gait or different activity levels.

[0082] Referring to FIG. 8, the prosthetic knee device 100 operates during the early stance phase of gait with specific mechanical configurations that provide stability and prevent unwanted knee buckling under body weight loads. The figure shows the approximate line of action of the ground reaction forces 108 as well as the position of the instantaneous center of rotation 106 and the configuration of the slider crank mechanism 180 during this phase of gait. The ground reaction force vector 108 acts anteriorly relative to the instantaneous center of rotation 106 of the thigh portion 110, creating a moment arm that generates an extension torque about the knee joint. This extension torque helps maintain knee stability by opposing any flexion forces that might otherwise cause the knee to buckle during weight bearing. The slider crank mechanism 180 operates near its singular configuration during early stance, where the three rotational axes of the mechanism approach collinear alignment, minimizing the transmission of compressive forces from the lower shank portion 130 to rotational torques about the knee joint.

[0083] The stability characteristics during early stance phase result from the coordinated operation of both the four-bar linkage mechanism 140 and the slider crank mechanism 180 working together to resist knee flexion under load. The instantaneous center of rotation 106 of the four-bar linkage 140 occupies a position that places the ground reactionAttorney Docket Number: 09 05407 1112 force 108 line of action anterior to the center, generating the beneficial extension moment that stabilizes the knee joint. Simultaneously, the near-singular configuration of the slider crank mechanism 180 prevents the compressive forces acting along the translational axis 126 between the upper shank portion 120 and lower shank portion 130 from inducing flexion torques about the knee. The combination of these two mechanical effects creates a stable configuration where the prosthetic knee device 100 can support body weight without compromising joint stability or allowing unwanted knee motion during the weight-bearing phase of gait.

[0084] As further shown in FIG. 8, the geometric relationships between the linkage components determine the magnitude and direction of the forces and moments that act on the knee joint during early stance phase. The positioning of the instantaneous center of rotation 106 depends on the current angular configuration of the four-bar linkage mechanism 140, which varies as a function of the relative positions of the anterior link 150 and posterior link 1 0. The slider crank mechanism 180 approaches its singular configuration w hen the posterior link 160, coupler link 170, and lower shank portion 130 alignment creates the collinear condition of the rotational axes. The proximity to this singular configuration controls how effectively the mechanism isolates the knee joint from the effects of ground reaction forces 108 and body w eight loads that act on the lower shank portion 130 during stance phase.

[0085] Referring to FIG. 9, the prosthetic knee device 100 operates during the late stance phase of gait with altered mechanical relationships that facilitate the transition from stance phase stability’ to swing phase knee flexion. The figure demonstrates that the approximate line of action of the ground reaction force 108 has shifted to a position posterior to the instantaneous center of rotation 106 of the thigh portion 110, creating a fundamental change in the moment relationships about the knee joint. This posterior positioning of the ground reaction force 108 line of action generates a flexion torque about the instantaneous center of rotation 106, causing the knee to begin flexing and initiating the transition to swing phase. The change in ground reaction force 108 direction occurs naturally during the progression of the gait cycle as the center of pressure moves from the heel toward the toe during the stance phase, eventually reaching a position where the force vector passes behind the instantaneous center of rotation 106.

[0086] The transition from early stance to late stance phase involves a progressive shift in the mechanical advantage and force transmission characteristics of the linkage system as the knee joint configuration changes. During late stance, the four-bar linkage mechanism 140Attorney Docket Number: 09 05407 1112 moves through angular positions that relocate the instantaneous center of rotation 106 relative to the ground reaction force vector 108. The slider crank mechanism 180 begins to move away from its singular configuration as the knee starts to flex, allowing the coupling between knee rotation and leg length adjustment to become active. The posterior link 1 0 of the slider crank mechanism 180 begins to rotate as the knee flexes, driving the coupler link 170 and initiating the translational movement of the lower shank portion 130 relative to the upper shank portion 120. This coordinated motion creates the leg length shortening that provides increased foot clearance during the subsequent swing phase.

[0087] With continued reference to FIG. 9, the mechanical coupling between the four- bar linkage mechanism 140 and the slider crank mechanism 180 becomes active during late stance phase as the knee begins to flex in response to the changed ground reaction force 108 moment. The rotation of the posterior link 160, which serves as both a component of the four- bar linkage mechanism 140 and the driving element of the slider crank mechanism 180, transfers the knee flexion motion to the translational system that controls leg length. The coupler link 170 follows the motion of the posterior link 160, creating the kinematic chain that drives the lower shank portion 130 to translate proximally relative to the upper shank portion 120. The leg length retraction begins during late stance phase and continues into swing phase, providing the increased ground clearance that reduces the risk of tripping or stumbling during the swing phase of gait.

[0088] In some implementations, the timing and magnitude of the transition between stance phase stability’ and swing phase coupling may be adjusted through modifications to the four-bar linkage geometry or the slider crank mechanism 180 parameters. The position of the instantaneous center of rotation 106 during different knee angles may be controlled through the selection of anterior link 150 and posterior link 160 lengths and the positioning of the pivot points that connect these links to the thigh portion 1 10 and upper shank portion 120. The angular range over which the slider crank mechanism 180 operates near its singular configuration may be modified through changes to the link lengths and pivot locations within the slider crank assembly. The mechanical advantage between knee flexion and leg length retraction may be adjusted through the geometric relationships within the coupler link 170 and the positioning of the rotational coupling points.

[0089] In some implementations, the ground reaction force 108 characteristics and their interaction with the instantaneous center of rotation 106 may be influenced by the overall prosthetic system configuration, including the prosthetic foot design and the alignment of theAttorney Docket Number: 09 05407 1112 prosthetic components relative to the user's anatomy. The prosthetic foot may incorporate specific mechanical characteristics that affect the center of pressure progression during stance phase, influencing the timing of the transition from extension torque to flexion torque about the knee joint. The alignment of the prosthetic knee device 100 relative to the prosthetic foot and the prosthetic socket may be adjusted to optimize the relationship between the ground reaction force vector 108 and the instantaneous center of rotation 106 during different phases of gait. Additional mechanical elements such as bumpers, stops, or damping components may be incorporated to control the transition characteristics between stance and swing phases.

[0090] Referring to FIGS. 10A-10E, the prosthetic knee device 100 demonstrates a complete range of motion that shows the progressive relationship between knee flexion angles and corresponding leg length adjustments throughout the full operational range. FIG. 10A shows the prosthetic knee device 100 in a fully extended configuration where the thigh portion 110 and upper shank portion 120 are aligned in a straight configuration, representing the stance phase position where maximum leg length is maintained for proper ground contact and weight bearing. The lower shank portion 130 occupies its most distal position relative to the upper shank portion 120. creating the full extended length of the prosthetic limb. The four-bar linkage mechanism 140 positions the anterior link 150 and posterior link 160 in angular orientations that create the extended knee configuration, while the slider crank mechanism 180 approaches its singular configuration where the posterior link 160, coupler link 170, and lower shank portion 130 alignment minimizes the coupling between translational forces and rotational motion.

[0091] As shown in FIG. 10B, initial knee flexion produces the first stage of leg length retraction as the thigh portion 110 begins to rotate relative to the upper shank portion 120. The four-bar linkage mechanism 140 guides the rotational motion through the anterior link 150 and posterior link 160, creating controlled knee flexion while the instantaneous center of rotation 106 shifts position according to the linkage geometry. The posterior link 160 rotation drives the slider crank mechanism 180 as the coupler link 170 begins to follow the motion of the posterior link 160, initiating the translational movement of the lower shank portion 130 toward the upper shank portion 120. The leg length shortening becomes apparent as the lower shank portion 130 moves proximally relative to the upper shank portion 120, reducing the overall length of the prosthetic limb while maintaining structural alignment betw een the components.

[0092] With continued reference to FIGS. 10A-10E, FIG. 10C demonstrates increased knee flexion with corresponding progression of leg length retraction as the mechanicalAttorney Docket Number: 09 05407 1112 coupling between rotational and translational motion becomes more pronounced. The four-bar linkage mechanism 140 continues to guide the knee flexion motion while the slider crank mechanism 180 operates away from its singular configuration, allowing full coupling between the posterior link 160 rotation and the translational movement of the lower shank portion 130. The coupler link 170 follows a complex motion path that combines rotational and translational components as the posterior link 160 continues to rotate, driving the lower shank portion 130 further proximally relative to the upper shank portion 120. The leg length retraction reaches an intermediate level that provides increased ground clearance during swing phase while maintaining the structural integrity and alignment of the prosthetic knee device 100 components.

[0093] FIG. 10C shows the prosthetic knee device 100 at the point of maximum leg length retraction, where the knee flexion angle produces the shortest overall limb length within the operational range. The four-bar linkage mechanism 140 positions the anterior link 150 and posterior link 160 at angular orientations that correspond to moderate knee flexion, while the slider crank mechanism 180 reaches the configuration that produces maximum translational displacement of the lower shank portion 130 toward the upper shank portion 120. The coupler link 170 occupies a position where the kinematic relationships within the slider crank mechanism 180 create the peak retraction condition, representing the transition point where further knee flexion will begin to reverse the leg length adjustment direction. The maximum retraction configuration provides the greatest ground clearance benefit during swing phase, reducing the risk of tripping or stumbling when the prosthetic limb swings forward during walking.

[0094] As further shown in FIGS. 10A-10E, FIG. 10D demonstrates the prosthetic knee device 100 at a large knee flexion angle where the coupling relationship has inverted and leg length extension begins to occur despite continued knee flexion. The four-bar linkage mechanism 140 accommodates the large flexion angle through the anterior link 150 and posterior link 160 positioning, while the slider crank mechanism 180 operates in a configuration where the kinematic relationships produce leg length extension rather than retraction. The coupler link 170 motion drives the lower shank portion 130 distally relative to the upper shank portion 120, extending the leg length back toward the original extended configuration even though the knee remains in a flexed position. The inverted coupling relationship provides functional benefits during activities that require large knee flexionAttorney Docket Number: 09 05407 1112 angles, such as sitting or deep knee bends, where excessive leg length retraction would create cosmetic or functional limitations.

[0095] FIGS. 13A-13F demonstrate the complete range of motion through six sequential configurations of another implementation of a prosthetic knee device 100 that show the detailed progression of both knee flexion and leg length adjustment throughout the operational range. FIG. 13A shows the prosthetic knee device 100 in the initial extended configuration where the thigh portion 110 and upper shank portion 120 maintain near-straight alignment, representing the stance phase position where the slider crank mechanism 180 operates near its singular configuration. The mechanical linkages position the components to provide stance phase stability while the lower shank portion 130 occupies its most distal position relative to the upper shank portion 120. creating the full extended leg length. The four- bar linkage mechanism 140 and slider crank mechanism 180 work together to support body weight loads without allowing unwanted knee flexion during the weight-bearing phase of gait.

[0096] FIG. 13B demonstrates the first stage of knee flexion where the thigh portion 110 begins to rotate relative to the upper shank portion 120. initiating the coupling between rotational motion and leg length adjustment. The four-bar linkage mechanism 140 guides the initial knee flexion through controlled motion of the anterior link 150 and posterior link 160, while the slider crank mechanism 180 begins to move away from its singular configuration as the posterior link 160 starts to rotate. The coupler link 170 begins to follow the posterior link 160 motion, creating the initial translational movement of the lower shank portion 130 toward the upper shank portion 120. The leg length shortening becomes apparent as the mechanical coupling transfers the rotational motion of the knee joint into the linear motion that reduces the overall prosthetic limb length.

[0097] With continued reference to FIGS. 13A-13F, FIG. 13C shows progressive knee flexion with increased leg length retraction as the mechanical coupling operates more effectively away from the singular configuration. The four-bar linkage mechanism 140 continues to provide controlled knee motion while the slider crank mechanism 180 transfers the posterior link 160 rotation through the coupler link 170 to drive further translational movement of the low er shank portion 130. The leg length continues to shorten as the lower shank portion 130 moves proximally relative to the upper shank portion 120, providing increased ground clearance that reduces the risk of tripping during swing phase. The mechanical advantage of the slider crank mechanism 180 creates a proportional relationshipAttorney Docket Number: 09 05407 1112 between the degree of knee flexion and the magnitude of leg length retraction during this phase of the motion range.

[0098] FIG. 13C demonstrates the prosthetic knee device 100 approaching the point of maximum leg length retraction where the knee flexion angle produces the shortest overall limb configuration. The four-bar linkage mechanism 140 accommodates the moderate knee flexion angle while the slider crank mechanism 180 reaches the kinematic configuration that produces peak translational displacement of the lower shank portion 130 toward the upper shank portion 120. The coupler link 170 occupies the position where the geometric relationships within the slider crank mechanism 180 create the maximum retraction condition, representing the transition point in the coupling relationship. The maximum retraction provides the greatest swing phase ground clearance benefit while maintaining the structural alignment and mechanical integrity of the prosthetic knee device 100 components throughout the motion range.

[0099] As further shown in FIGS. 13A-13F, FIG. 13D shows the prosthetic knee device 100 at increased knee flexion where the coupling relationship begins to invert and leg length starts to extend despite continued knee flexion motion. The four-bar linkage mechanism 140 accommodates the larger flexion angle through the positioning of the anterior link 150 and posterior link 160, while the slider crank mechanism 180 operates in the kinematic configuration where further posterior link 160 rotation drives the coupler link 170 to produce leg length extension rather than retraction. The lower shank portion 130 begins to move distally relative to the upper shank portion 120, extending the leg length back toward the original configuration even though the knee remains in a flexed position. The inverted coupling relationship demonstrates the second singular configuration of the mechanism where the kinematic relationships change direction to provide different functional characteristics.

[0100] FIG. 13F demonstrates the prosthetic knee device 100 at a large knee flexion angle where the leg length has extended back to near the original length despite the significant knee flexion. The four-bar linkage mechanism 140 accommodates the large flexion angle while the slider crank mechanism 180 operates in the fully inverted coupling configuration where the coupler link 170 drives the lower shank portion 130 to its extended position relative to the upper shank portion 120. The leg length extension during large knee flexion angles provides cosmetic and functional benefits during activities such as sitting, where maintaining appropriate leg length proportions prevents undesirable appearance or functional limitations. The mechanical coupling continues to operate effectively throughout the full range of motion,Attorney Docket Number: 09 05407 1112 providing coordinated control of both knee flexion and leg length adjustment across all operational configurations.

[0101] In some implementations, the range of motion characteristics may be modified through adjustments to the linkage geometry, pivot locations, or mechanical advantage ratios within the coupling mechanism. The angular ranges that define different phases of the coupling relationship may be shifted to optimize the leg length adjustment characteristics for specific user requirements or activity patterns. The magnitude of maximum leg length retraction may be controlled through the selection of link lengths and geometric relationships within the slider crank mechanism 180, allowing customization of the swing phase clearance benefits. The transition point between leg length retraction and extension may be adjusted through modifications to the coupler link 170 geometry or the positioning of the rotational coupling points within the slider crank mechanism 180.

[0102] In some implementations, the motion range may incorporate additional mechanical elements that modify the relationship between knee flexion and leg length adjustment throughout different portions of the operational range. Variable mechanical advantage systems may be employed to create non-linear coupling relationships that provide different rates of leg length change per degree of knee flexion in different angular ranges. Spring elements may be integrated into the linkage system to provide bias forces that influence the coupling behavior or assist in leg length extension during specific phases of the motion range. Damping elements may be incorporated to control the rate of leg length change and provide smooth transitions between different coupling regions, enhancing the user experience during activities that require motion through the full range of knee flexion angles.

[0103] The prosthetic knee device 100 may incorporate alternative linkage configurations that provide enhanced functionality beyond the four-bar linkage mechanism 140 described above. Five-bar linkage systems may replace the four-bar linkage that couples the thigh portion 110 to the upper shank portion 120, offering additional degrees of freedom and motion characteristics that enhance prosthetic performance during different phases of gait. The five-bar linkage mechanism comprises the thigh portion 110, the upper shank portion 120, an anterior link 150, a posterior link 160. and an additional intermediate link that creates a more complex kinematic chain. The intermediate link may be rotatably coupled between the anterior link 150 and posterior link 160, creating additional pivot points that modify' the instantaneous center of rotation 106 characteristics and provide enhanced control over the knee motion trajectory. The five-bar configuration may provide additional functionality of early stance kneeAttorney Docket Number: 09 05407 1112 flexion, allowing controlled knee bending during the initial contact phase of gait while maintaining overall stability throughout the stance phase.

[0104] The five-bar linkage system may offer enhanced biomechanical compatibility by more closely replicating the complex motion patterns found in biological knee joints. The additional intermediate link creates multiple instantaneous centers of rotation 106 that shift position throughout the range of motion, providing motion characteristics that may better match natural knee kinematics compared to simpler four-bar configurations. The five-bar mechanism may also provide improved control over the relationship between knee flexion angle and the position of the instantaneous center of rotation 106, allowing for optimization of stance phase stability characteristics while maintaining swing phase functionality . The additional mechanical complexity of the five-bar system may be balanced against the enhanced performance characteristics to determine the optimal configuration for specific user requirements and activity levels.

[0105] In some implementations, the thigh portion 110 may be coupled to the upper shank portion 120 via weight activated stance control joints that provide automatic locking and unlocking based on the loading conditions experienced during different phases of gait. Weight activated stance control mechanisms may comprise load sensing elements that detect the presence or absence of ground reaction forces 108 and body weight loading, automatically engaging locking mechanisms during stance phase and disengaging during swing phase. The weight activated system may incorporate spring-loaded components, hydraulic elements, or mechanical linkages that respond to the compressive forces applied to the prosthetic knee device 100 during weight bearing. The automatic operation of weight activated stance control joints may eliminate the need for electronic control systems or user in ten ention while providing reliable stance phase stability and swing phase mobility.

[0106] In some implementations, the thigh portion 110 may be coupled to the upper shank portion 120 via mechanisms with separate knee axes and locking axes that provide independent control over the rotational motion and the locking functionality. The separate axis configuration may comprise a primary knee axis that governs the flexion and extension motion of the joint, and a secondary locking axis that controls the engagement and disengagement of stance phase stability’ mechanisms. The locking axis may operate perpendicular to the knee axis or at other angular orientations that optimize the mechanical advantage and force transmission characteristics of the locking system. The separation of the knee axis and locking axis may allow for independent optimization of the motion characteristics and stabilityAttorney Docket Number: 09 05407 1112 characteristics, providing enhanced performance compared to systems where both functions share the same rotational axis.

[0107] The prosthetic knee device 100 may incorporate a damping mechanism that is kinematically coupled to the motion of the thigh portion 110 relative to the upper shank portion 120 to provide controlled resistance during knee flexion and extension motions. The damping mechanism may comprise various configurations that generate resistive forces proportional to the velocity of knee motion, providing smooth and controlled movement during both stance and swing phases of gait. The kinematic coupling between the damping mechanism and the knee motion may be achieved through direct connection to the rotational components of the four-bar linkage mechanism 140, or through intermediate mechanical linkages that transfer the knee motion to the damping elements. The damping mechanism may operate continuously throughout the range of knee motion or may be selectively engaged during specific phases of gait to provide targeted control characteristics.

[0108] The damping mechanism may comprise a pneumatic actuator that utilizes compressed air or gas to generate controlled resistance forces during knee motion. Pneumatic damping systems may incorporate cylinders, pistons, and valve assemblies that regulate the flow of compressed air to create velocity-dependent damping characteristics. The pneumatic actuator may include adjustable orifices or variable valve settings that allow for customization of the damping characteristics based on user preferences or activity requirements. The pneumatic system may also incorporate accumulator chambers or pressure regulation components that maintain consistent damping performance across different operating conditions and environmental temperatures.

[0109] In some implementations, the damping mechanism may comprise a hydraulic actuator that utilizes fluid flow resistance to generate controlled damping forces during knee motion. Hydraulic damping systems may incorporate fluid-filled chambers, pistons, and flow control valves that regulate the movement of hydraulic fluid to create smooth and consistent resistance characteristics. The hydraulic actuator may include variable orifice systems that allow for adjustment of the damping characteristics during different phases of gait or different activity levels. The hydraulic system may also incorporate temperature compensation features that maintain consistent damping performance across different environmental conditions, and may include filtration systems that prevent contamination of the hydraulic fluid over extended periods of use.Attorney Docket Number: 09 05407 1112

[0110] In some implementations, the damping mechanism may comprise a friction swing control unit that generates resistance forces through controlled friction between mating surfaces during knee motion. Friction-based damping systems may incorporate disc assemblies, brake pad configurations, or other friction elements that create velocity-dependent resistance characteristics. The friction swing control unit may include adjustable clamping mechanisms that allow for modification of the friction force levels based on user requirements or activity patterns. The friction elements may be constructed from materials selected for appropriate coefficient of friction values, wear resistance, and consistent performance characteristics over extended periods of operation.

[0111] In some implementations, the damping mechanism may comprise a magnetorheological damper that utilizes magnetic field-controlled fluid properties to generate variable damping characteristics. Magnetorheological damping systems may incorporate specialized fluids containing magnetic particles that change viscosity in response to applied magnetic fields, allowing for real-time adjustment of damping characteristics. The magnetorheological damper may include electromagnetic coils that generate controlled magnetic fields to modulate the fluid properties and resulting damping forces. The magnetorheological system may be controlled through electronic systems that monitor gait phase and adjust the magnetic field strength to optimize damping characteristics for different phases of walking or other activities.

[0112] The prosthetic knee device 100 may incorporate an extension spring that is kinematically coupled to the motion of the thigh portion 1 10 relative to the upper shank portion 120 to provide assistive forces during knee extension motions. The extension spring may comprise various spring configurations including coil springs, leaf springs, or gas springs that store energy during knee flexion and release energy to assist knee extension during appropriate phases of gait. The kinematic coupling betw een the extension spring and the knee motion may be achieved through direct connection to the rotational components of the linkage mechanism, or through intermediate mechanical systems that transfer the knee motion to the spring elements. The extension spring may provide continuous assistance throughout the range of knee motion or may be configured to provide assistance only during specific angular ranges where extension assistance is beneficial.

[0113] In some implementations, a linear damper may be located within the translational coupling betw een the upper shank portion 120 and the low er shank portion 130 to provide controlled resistance during leg length adjustment motions. The linear damper mayAttorney Docket Number: 09 05407 1112 comprise cylinder and piston assemblies that generate velocity -dependent resistance forces as the lower shank portion 130 translates relative to the upper shank portion 120. The linear damper may incorporate adjustable flow control elements that allow for customization of the damping characteristics based on the desired rate of leg length change during different phases of gait. The linear damper may also include bidirectional damping capabilities that provide different resistance characteristics during leg length retraction compared to leg length extension, optimizing the control characten sties for both swing phase and stance phase operations.

[0114] In some implementations, an extension spring may be located within the translational coupling between the upper shank portion 120 and the lower shank portion 130 to provide assistive forces during leg length extension motions. The extension spring may’ comprise various spring configurations that store energy during leg length retraction and release energy to assist leg length extension when the coupling mechanism drives the lower shank portion 130 back toward its extended position. The extension spring may be configured to provide bias forces that assist in returning the leg length to its extended configuration during stance phase, reducing the energy required from the user to operate the leg length adjustment mechanism. The spring characteristics may be selected to provide appropriate force levels that assist the mechanical coupling without interfering with the desired leg length retraction during swing phase.

[0115] The prosthetic knee device 100 may incorporate additional actuators or mechanisms that operate as mechanically passive units, providing resistance or assistance forces without external power sources or electronic control systems. Mechanically passive actuators may comprise spring elements, damping components, or friction devices that respond to the mechanical inputs from the knee motion and leg length adjustment mechanisms. The passive actuators may be configured to provide specific force-displacement or force-velocity relationships that enhance the performance characteristics of the prosthetic knee device 100 during different phases of gait. The passive nature of these actuators may provide reliable operation without the complexity’, weight, or power requirements associated with active control systems.

[0116] In some implementations, the prosthetic knee device 100 may incorporate active units including powered actuators that provide active torque during stance phase or swing phase operations. Active actuators may comprise electric motors, hydraulic motors, or pneumatic actuators that generate controlled forces or torques based on electronic controlAttorney Docket Number: 09 05407 1112 signals. The powered actuators may be integrated with the rotational coupling between the thigh portion 110 and upper shank portion 120 to provide active assistance or resistance during knee flexion and extension motions. The active actuators may also be integrated with the translational coupling between the upper shank portion 120 and lower shank portion 130 to provide powered control over the leg length adjustment mechanism. The active control systems may incorporate sensors that monitor gait phase, ground contact forces, or other parameters to optimize the timing and magnitude of the active assistance provided by the powered actuators.

[0117] In some implementations, mechanically passive actuators or mechanisms may be paired with motors or other actuators to modulate the passive characteristics and provide variable performance capabilities. A damper with variable damping levels may comprise a passive damping element combined with an active control system that adjusts the damping characteristics based on operating conditions or user preferences. The variable damping system may incorporate adjustable orifices, variable magnetic fields, or other control mechanisms that modify the resistance characteristics of the passive damping element. The combination of passive and active elements may provide the reliability and simplicity of passive systems while offering the adaptability and optimization capabilities of active control systems. The variable characteristics may be adjusted automatically based on sensor inputs or may be manually adjusted by the user to accommodate different activity levels or environmental conditions.

[0118] FIG. 14 shows the implementation of the prosthetic knee mechanism 100 of FIGS. 13A-13F in a three-dimensional arrangement of components through a perspective view that reveals the spatial relationships between the thigh portion 1 10, upper shank portion 120, and lower shank portion 130. The perspective view shows how the four-bar linkage mechanism 140 integrates with the slider crank mechanism 180 to create a unified mechanical system that coordinates knee rotation with leg length adjustment. The anterior link 150 and posterior link 160 extend between the thigh portion 110 and upper shank portion 120, creating the parallel linkage configuration that governs the rotational motion of the knee joint. The coupler link 170 connects the posterior link 160 to the lower shank portion 130, establishing the kinematic chain that transfers rotational motion from the knee joint to the translational movement of the lower shank portion 130. The perspective view illustrates how the various rotational coupling points align in three-dimensional space to create the desired motion characteristics while maintaining structural integrity’ throughout the range of operation.

[0119] The three-dimensional perspective reveals the mechanical interfaces between components and demonstrates how the linkage elements occupy different planes within theAttorney Docket Number: 09 05407 1112 overall assembly. The rotational coupling points between the links and the main structural components create multiple axes of rotation that operate simultaneously to produce the coordinated motion between knee flexion and leg length adjustment. The prismatic coupling between the upper shank portion 120 and lower shank portion 130 appears as a sliding interface that constrains the translational movement to a single axis 126 while preventing unwanted rotational motion between these components. The overall assembly demonstrates the compact integration of multiple mechanical systems within the prosthetic knee mechanism 100, showing how the four-bar linkage mechanism 140 and slider crank mechanism 180 work together without interference or mechanical conflict between the moving components.

[0120] Referring to FIGS. 15 and 16, the top and bottom views of the prosthetic knee mechanism 100 provides a different perspective that emphasizes the lateral spacing and alignment of the linkage components within the overall assembly. The top view shows the positioning of the anterior link 150 and posterior link 160 relative to the centerline of the prosthetic knee mechanism 100, revealing how these components are distributed across the width of the device to provide structural stability and mechanical advantage. The rotational coupling points between the links and the thigh portion 110 appear as pivot connections that allow- the links to rotate in the plane perpendicular to the viewing direction. The upper shank portion 120 demonstrates the structural features that accommodate both the rotational couplings from the four-bar linkage mechanism 140 and the prismatic coupling that guides the translational movement of the lower shank portion 130. The top view illustrates the symmetrical or asymmetrical arrangement of components depending on the specific design configuration selected for the prosthetic knee mechanism 100.

[0121] The top view perspective demonstrates how the mechanical components are arranged to avoid interference during the full range of motion while maintaining the structural strength needed to support body weight loads during stance phase. The spacing between the anterior link 150 and posterior link 160 creates the mechanical base that determines the stability' characteristics of the four-bar linkage mechanism 140, with wider spacing generally- providing enhanced stability at the expense of increased overall width of the prosthetic knee mechanism 100. The positioning of the coupler link 170 relative to the posterior link 160 appears in the top view' as the connection that transfers motion from the four-bar linkage mechanism 140 to the slider crank mechanism 180. The lower shank portion 130 shows the structural features that accommodate the prismatic coupling while providing the attachment interface for the prosthetic foot assembly.Attorney Docket Number: 09 05407 1112

[0122] With continued reference to FIG. 16. the top view configuration demonstrates the detailed arrangement of the rotational coupling interfaces and the mechanical clearances between moving components during different phases of operation. The view shows how the linkage components maintain proper alignment and spacing throughout the range of knee motion, preventing mechanical interference while ensuring smooth operation of both the rotational and translational degrees of freedom. The structural elements of the thigh portion 110, upper shank portion 120, and lower shank portion 130 appear as the framework that supports the linkage mechanisms while providing the attachment interfaces for connection to the prosthetic socket and prosthetic foot. The top view reveals the distribution of mechanical loads across the various coupling points and demonstrates how the forces generated during walking are transmitted through the linkage system to the main structural components of the prosthetic knee mechanism 100.

[0123] Referring to FIGS. 17 and 18, the front and rear views of the prosthetic knee mechanism 100 provides a perspective that emphasizes the vertical alignment and proportional relationships between the thigh portion 110, upper shank portion 120, and lower shank portion 130. The front view shows the overall height and profile of the prosthetic knee mechanism 100, demonstrating how the device maintains appropriate dimensional characteristics that match the proportions of biological limbs. The four-bar linkage mechanism 140 appears in the front view as the rotational coupling system that connects the thigh portion 110 to the upper shank portion 120. with the anterior link 150 and posterior link 160 visible as the parallel elements that create the controlled rotational motion. The slider crank mechanism 180 components appear as the mechanical system that enables the translational movement of the lower shank portion 130, with the coupler link 170 providing the connection between the rotational motion of the posterior link 160 and the linear motion of the lower shank portion 130.

[0124] The front view perspective illustrates the range of translational movement available to the lower shank portion 130 relative to the upper shank portion 120, showing how the leg length adjustment capability integrates with the overall structural design of the prosthetic knee mechanism 100. The prismatic coupling between the upper shank portion 120 and lower shank portion 130 appears as the sliding interface that guides the translational movement while maintaining proper alignment between these components. The front view demonstrates the mechanical clearances and structural features that accommodate the full range of motion without interference between moving components. The overall profile shownAttorney Docket Number: 09 05407 1112 in the front view reveals how the prosthetic knee mechanism 100 maintains a streamlined appearance that provides functional performance while meeting cosmetic requirements for prosthetic limb applications.

[0125] As further shown in FIG. 17, the front view reveals the vertical distribution of mechanical components and demonstrates how the linkage mechanisms integrate with the main structural elements of the prosthetic knee mechanism 100. The rotational coupling points between the various links and the thigh portion 110 and upper shank portion 120 appear as pivot connections that allow controlled motion while transmitting the forces and moments generated during walking and other activities. The positioning of the coupler link 170 relative to the other components shows how the slider crank mechanism 180 coordinates the motion between the rotational and translational degrees of freedom. The lower shank portion 130 demonstrates the structural features that provide the attachment interface for the prosthetic foot while accommodating the translational movement capability that distinguishes the prosthetic knee mechanism 100 from conventional designs.

[0126] Referring to FIG. 18, the rear view of the prosthetic knee mechanism 100 provides a perspective that shows the back side arrangement of components and reveals structural details that may not be visible from other viewing angles. The rear view demonstrates how the linkage mechanisms are supported and guided by the main structural components of the thigh portion 110, upper shank portion 120, and lower shank portion 130. The four-bar linkage mechanism 140 appears from the rear perspective as the system of parallel links that create the controlled rotational motion between the thigh portion 1 10 and upper shank portion 120. The posterior link 160 shows the dual function as both a component of the four-bar linkage mechanism 140 and the driving element of the slider crank mechanism 180 that controls leg length adjustment. The rear view illustrates the mechanical interfaces and structural features that support the various rotational coupling points while providing access for maintenance or adjustment of the prosthetic knee mechanism 100.

[0127] The rear view perspective demonstrates the structural continuity between the different components and shows how the mechanical loads are distributed through the linkage system during operation. The positioning of the coupler link 170 appears from the rear view as the connection that transfers motion from the posterior link 160 to the lower shank portion 130, creating the kinematic chain that coordinates knee flexion with leg length retraction. The prismatic coupling between the upper shank portion 120 and lower shank portion 130 shows the structural features that guide the translational movement while preventing unwantedAttorney Docket Number: 09 05407 1112 motion in other directions. The rear view reveals the overall structural design that provides the strength and durability needed for prosthetic applications while accommodating the complex mechanical systems that enable the coordinated motion between rotational and translational degrees of freedom.

[0128] Referring to FIG. 12, the prosthetic knee device 100 demonstrates substantial performance benefits through enhanced foot clearance during swing phase compared to conventional prosthetic knees without leg length adjustment capability. The graph shows simulated foot clearance data that compares the performance of the prosthetic knee device 100 with leg length retraction against a baseline condition without retraction functionality. The data reveals that one implementation of the prosthetic knee device 100 with leg length adjustment achieves significantly larger foot clearance values throughout the swing phase of gait, with peak clearance improvements reaching approximately 15-20 millimeters compared to the conventional configuration. The enhanced clearance occurs during the critical mid-swing phase when the prosthetic limb swings forward and the risk of ground contact or tripping reaches maximum levels during normal walking activities.

[0129] The foot clearance improvements shown in FIG. 12 result directly from the mechanical coupling between knee flexion and leg length retraction that operates during swing phase. As the knee flexes during the initial portion of swing phase, the slider crank mechanism 180 drives the lower shank portion 130 proximally relative to the upper shank portion 120. reducing the overall length of the prosthetic limb. The leg length shortening creates additional vertical clearance between the prosthetic foot and the ground surface, reducing the likelihood that the foot will contact obstacles, uneven terrain, or surface irregularities during the swing phase. The timing of the leg length retraction coincides with the natural knee flexion that occurs during swing phase, creating a coordinated motion that maximizes the clearance benefits without requiring additional user effort or conscious control of the prosthetic knee device 100.

[0130] With continued reference to FIG. 12, the comparative data demonstrates that conventional prosthetic knees without leg length adjustment capability maintain relatively constant foot clearance values that depend solely on the degree of knee flexion achieved during swing phase. The prosthetic knee device 100 with leg length retraction capability’ shows dramatically improved clearance characteristics, with peak values occurring during mid-swing when the combination of knee flexion and leg length shortening creates the maximum vertical separation between the foot and ground. The enhanced clearance profile provides a safetyAttorney Docket Number: 09 05407 1112 margin that reduces the risk of tripping or stumbling during walking on level surfaces, uneven terrain, or when encountering obstacles or surface irregularities.

[0131] The performance benefits extend beyond the peak clearance improvements to include enhanced clearance characteristics throughout the entire swing phase duration. The prosthetic knee device 100 maintains elevated foot clearance values from the initial swing phase through toe-off until the preparation for heel contact during the subsequent stance phase. The sustained clearance improvements provide consistent protection against ground contact throughout the swing phase, rather than brief periods of enhanced clearance that might occur with other swing phase control mechanisms. The gradual transition from maximum clearance back to ground contact preparation occurs as the knee extends and the leg length returns to full extension, coordinating the clearance benefits with the natural gait cycle progression.

[0132] As further shown in FIG. 12, the foot clearance data demonstrates the quantitative benefits that address the fall risk factors associated with prosthetic limb use during walking activities. The enhanced clearance values directly correspond to reduced trip risk during swing phase, as the increased vertical separation between the foot and ground provides greater tolerance for surface irregularities, obstacles, or variations in walking technique. The clearance improvements occur automatically through the mechanical coupling between knee motion and leg length adjustment, eliminating the need for conscious user control or adaptation of walking patterns to achieve the safety benefits. The consistent clearance enhancement across different phases of swing provides comprehensive protection against the ground contact events that contribute to falls and injuries among prosthetic limb users.

[0133] In some implementations, the foot clearance benefits may be further enhanced through modifications to the mechanical coupling characteristics or the geometric relationships within the slider crank mechanism 180. The magnitude of leg length retraction may be adjusted through changes to the link lengths or pivot locations within the slider crank mechanism 180, allowing customization of the clearance improvements based on user requirements or walking patterns. The timing of maximum leg length retraction relative to the swing phase progression may be modified through adjustments to the four-bar linkage geometry or the coupling between the posterior link 160 and the slider crank mechanism 180. Alternative linkage configurations may provide different clearance profiles that optimize the benefits for specific user populations or activity levels while maintaining the fundamental coupling between knee flexion and leg length adjustment.Attorney Docket Number: 09 05407 1112

[0134] In some implementations, the performance benefits may extend to walking conditions beyond level ground surfaces, including uneven terrain, stairs, or obstacle navigation scenarios. The leg length adjustment capability may provide enhanced clearance benefits during uphill or downhill walking, where the ground surface angle creates additional challenges for maintaining adequate foot clearance during swing phase. The prosthetic knee device 100 may demonstrate improved performance during stair climbing or descent activities, where the leg length adjustment provides additional clearance for navigating step edges or surface transitions. The mechanical coupling may also provide benefits during obstacle avoidance maneuvers, where the enhanced foot clearance creates greater tolerance for stepping over or around objects encountered during walking activities.

[0135] In some implementations, the foot clearance benefits may be combined with other swing phase control mechanisms to provide comprehensive swing phase performance optimization. Damping mechanisms may be integrated with the leg length adjustment capability to control the rate of clearance change and provide smooth transitions between different clearance levels during swing phase. Extension springs may be incorporated to assist in the return of leg length to full extension during the preparation for stance phase, ensuring proper ground contact while maintaining the swing phase clearance benefits. Variable mechanical advantage systems may be employed to create non-linear clearance profiles that provide different clearance characteristics during different portions of swing phase, optimizing the benefits for specific phases of the gait cycle or different walking speeds and activity levels.

[0136] A number of example implementations are provided herein. How ever, it is understood that various modifications can be made without departing from the spirit and scope of the disclosure herein. As used in the specification, and in the appended claims, the singular forms “a,” “an.” “the” include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various implementations, the terms “consisting essentially of’ and “consisting of’ can be used in place of “comprising” and “including” to provide for more specific implementations and are also disclosed.

[0137] Disclosed are materials, systems, devices, methods, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for. or are products of the disclosed methods, systems, and devices. These and otherAttorney Docket Number: 09 05407 1112 components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutations of these components may not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a device is disclosed and discussed each and every' combination and permutation of the device are disclosed herein, and the modifications that are possible are specifically contemplated unless specifically indicated to the contrary. Likewise, any subset or combination of these is also specifically contemplated and disclosed. This concept applies to all aspects of this disclosure including, but not limited to, steps in methods using the disclosed systems or devices. Thus, if there are a variety of additional steps that can be performed, it is understood that each of these additional steps can be performed with any specific method steps or combination of method steps of the disclosed methods, and that each such combination or subset of combinations is specifically contemplated and should be considered disclosed.

Claims

Attorney Docket Number: 09 05407 1112CLAIMSWHAT IS CLAIMED IS:

1. A prosthetic knee device, comprising: a thigh portion; an upper shank portion, wherein the thigh portion is rotatable relative to the upper shank portion; and a lower shank portion translationally movable relative to the upper shank portion, wherein rotation of the thigh portion relative to the upper shank portion causes translational movement of the lower shank portion relative to the upper shank portion.

2. The prosthetic knee device of claim 1, further comprising a linkage configured to cause the translational movement of the lower shank portion relative to the upper shank portion.

3. The prosthetic knee device of claim 2, further comprising a linkage wherein the linkage comprises: an anterior link having a first end and a second end opposite and spaced apart from the first end of the anterior link, wherein the first end of the anterior link is rotatably coupled to a first portion of the thigh portion, wherein the second end of the anterior link is rotatably coupled to a first portion of the upper shank portion; a posterior link having a first end, a second end opposite and spaced apart from the first end of the posterior link, and an intermediate portion disposed between the first end of the posterior link and the second end of the posterior link, wherein the first end of the posterior link is rotatably coupled to a second portion of the thigh portion, wherein the intermediate portion of the posterior link is rotatably coupled to a second portion of the upper shank portion; and a coupler link having a first end and a second end opposite and spaced apart from the first end of the coupler link, wherein the first end of the coupler link is rotatably coupled to the second end of the posterior link, wherein the second end of the coupler link is rotatably coupled to the lower shank portion.

4. The prosthetic knee device of claim 1, wherein in a first region of motion of the thigh portion relative to the upper shank portion, rotation of the thigh portion relative to the upperAttorney Docket Number: 09 05407 1112 shank portion in a flexion direction is coupled with translational movement of the lower shank portion toward the upper shank portion.

5. The prosthetic knee device of claim 1, wherein in a second region of motion of the thigh portion relative to the upper shank portion, compressive forces acting along an axis of translation between the upper shank portion and the lower shank portion do not cause rotation of the thigh portion relative to the upper shank portion in a flexion direction.

6. The prosthetic knee device of claim 5, wherein the second region of motion includes full extension of the thigh portion relative to the upper shank portion.

7. The prosthetic knee device of claim 5, wherein the second region of motion includes knee flexion angles of less than 10 degrees.

8. The prosthetic knee device of claim 3, wherein the thigh portion, the upper shank portion, the anterior link, and the posterior link form a four-bar linkage mechanism.

9. The prosthetic knee device of claim 8, wherein the four-bar linkage mechanism provides an instantaneous center of rotation that moves in space as a function of a configuration of the four-bar linkage mechanism.

10. The prosthetic knee device of claim 9, wherein when the thigh portion is in full extension relative to the upper shank portion, the instantaneous center of rotation is positioned posteriorly and superiorly relative to the upper shank portion.

11. The prosthetic knee device of claim 9, wherein when the thigh portion is in full extension relative to the upper shank portion, the instantaneous center of rotation is positioned anteriorly and distally relative to the upper shank portion.

12. The prosthetic knee device of claim 1, further comprising a slider link prismatically coupled to the upper shank portion.

13. The prosthetic knee device of claim 1, further comprising a slider crank mechanismAttorney Docket Number: 09 05407 1112 comprising: a posterior link having a first end and a second end opposite and spaced apart from the first end of the posterior link, and an intermediate portion disposed between the first end of the posterior link and the second end of the posterior link, wherein the intermediate portion of the posterior link is rotatably coupled to the upper shank portion; and a coupler link having a first end and a second end opposite and spaced apart from the first end of the coupler link, wherein the first end of the coupler link is rotatably coupled to the second end of the posterior link, wherein the second end of the coupler link is rotatably coupled to the lower shank portion.

14. The prosthetic knee device of claim 13, wherein the slider crank mechanism further comprises the lower shank portion which is prismatically coupled to the upper shank portion.

15. The prosthetic knee device of claim 13, wherein the slider crank mechanism has a singular configuration in which an axis of rotation of the posterior link relative to the upper shank portion, an axis of rotation of the coupler link relative to the posterior link, and an axis of rotation of the coupler link relative to the lower shank portion are approximately connected via a straight line.

16. The prosthetic knee device of claim 15, wherein when the slider crank mechanism is in the singular configuration, forces applied to the lower shank portion along an axis of translation of the lower shank portion relative to the upper shank portion induce no torque about the axis of rotation of the posterior link.

17. The prosthetic knee device of claim 15, wherein the slider crank mechanism is near the singular configuration when the thigh portion is in full extension relative to the upper shank portion.

18. The prosthetic knee device of claim 1. wherein knee flexion is coupled to leg length retraction in a first region of knee angles corresponding to initial knee flexion and is coupled to leg length extension in a third region of knee angles corresponding to large knee flexion angles.Attorney Docket Number: 09 05407 111219. The prosthetic knee device of claim 1, further comprising a damping mechanism that is kinematically coupled to the motion of the thigh portion relative to the upper shank portion.

20. The prosthetic knee device of claim 19, wherein the damping mechanism comprises a pneumatic actuator, a hydraulic actuator, a friction swing control unit, or a magnetorheological damper.

21. The prosthetic knee device of claim 1, further comprising an extension spring that is kinematically coupled to the motion of the thigh portion relative to the upper shank portion.

22. The prosthetic knee device of claim 1, wherein the lower shank portion is configured to be coupled to a prosthetic foot.

23. The prosthetic knee device of claim 1, wherein the thigh portion is configured to be coupled to a prosthetic socket for attachment to a residual limb.

Images