Osseointegrated prosthesis interface health monitoring device and method

Abstract

The application provides a kind of bone integration prosthesis interface health monitoring device and method, the device includes detection rod, rotating propulsion mechanism, motion control unit and signal acquisition processing unit.Titanium implant part to be detected one end is implanted into femoral medullary cavity and is combined with bone tissue to form titanium-bone interface, and the other end is provided with detection hole in axial direction.Detection rod is composed of deep detection section, probe mounting section and connecting section;PZT piezoelectric wafer probe is arranged in probe mounting section, and phased array ultrasonic equipment is connected to emit and receive ultrasonic waves;45° reflecting sheet is arranged at the end of hollow deep detection section, for axial insertion into detection hole, and the inside and gap between hole wall are filled with ultrasonic coupling agent to build propagation path.Rotating propulsion mechanism is driven by motion control unit, controls detection rod to rotate around shaft and moves along detection hole in axial direction, and finally echo signal is processed by signal acquisition processing unit, to form axial-circumferential detection data of titanium-bone interface.

Description

Technical Field

[0001] This invention relates to the field of medical device structural health testing and non-destructive testing technology, specifically to a device and method for monitoring the health of the osseointegrated prosthesis interface. Background Technology

[0002] Osseointegrated prostheses, as an advanced functional prosthetic alternative, surgically fix the prosthesis directly to the human skeleton, achieving a rigid connection between the prosthesis and the host bone, resulting in higher stability and functionality. However, during long-term use, the bone-prosthesis interface may loosen due to stress concentration, bone loss, or micro-motion wear, and may even lead to host bone cracking. In addition, the residual limb-prosthesis interface also presents clinical problems such as uneven stress distribution and abnormal soft tissue compression.

[0003] Current clinical testing methods mainly rely on periodic X-ray imaging or CT scans, which not only pose radiation exposure risks and cannot achieve real-time continuous monitoring, but also struggle to detect micro-level micro-movements and loosening at interfaces in their early stages. To address the challenge of detecting internal structural defects, some research has been conducted in related fields. For example, Chinese patent CN110376285A discloses an ultrasonic testing method and device for cracks on the surface of ordinary threads in tie rod bolts. This technology uses a small-angle shear wave focusing probe, which emits shear waves onto the thread surface and deforms them into longitudinal waves. Combined with a contrast test block and a coupling agent, it achieves effective detection of cracks on the thread surface, improving the sensitivity and accuracy of the detection.

[0004] However, traditional industrial ultrasonic testing and the aforementioned testing methods for specific mechanical components (such as bolt threads) are mainly designed for homogeneous industrial metal components, and are poorly adapted to the complex internal structures and biological tissue interfaces of prostheses. Osseointegrated prosthetic systems contain multiple heterogeneous interfaces including metal, bone, and soft tissue, with significant differences in acoustic impedance. Existing ultrasonic technologies struggle to achieve comprehensive coverage, precise positioning, and non-invasive real-time monitoring of these interfaces, and their testing efficiency is low. Therefore, there is an urgent need for an intelligent monitoring technology and device capable of penetrating deep into the prosthesis and performing real-time, non-invasive, and high-precision testing of these multi-layered interfaces to enable early warning of loosening and health status assessment of osseointegrated prosthetic interfaces. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a device and method for monitoring the health of the osseointegrated prosthesis interface.

[0006] According to one aspect of the present invention, a health monitoring device for an osseointegrated prosthesis interface includes a detection rod, a rotation propulsion mechanism, a motion control unit, and a signal acquisition and processing unit. The detection rod includes a deep detection section, a probe mounting section, and a connecting section. Both the deep detection section and the probe mounting section are hollow structures. A PZT piezoelectric crystal probe is disposed in the probe mounting section. The PZT piezoelectric crystal probe is connected to a single-channel interface of a phased array ultrasonic control device via a wire. The PZT piezoelectric crystal probe is used to generate ultrasonic waves and receive echo signals. The ultrasonic waves generated by the PZT piezoelectric crystal probe propagate collimated axially in the deep detection section. One end of the deep detection section is connected to one end of the probe mounting section, and a reflective sheet is disposed at the other end of the deep detection section. The reflective surface of the reflective sheet completely covers the port of the deep detection section. The angle between the line and the axis of the deep detection section is 45°. The deep detection section is used to insert into the detection hole along the axis. The gap between the interior of the deep detection section and the outer wall of the deep detection section and the inner wall of the detection hole is filled with ultrasonic coupling agent to form the propagation path of ultrasonic waves. The connecting section is connected to the rotating propulsion mechanism, which is used to drive the detection rod to rotate around its own axis and move along the axis of the detection hole. The motion control unit is used to control the rotating propulsion mechanism to move according to the preset trajectory. The signal acquisition and processing unit is used to process the received echo signal to form axial and circumferential detection data of the titanium-bone interface. The detection hole is set along the axis on one end face of the titanium implant to be tested. The other end of the titanium implant to be tested is implanted into the medullary cavity of the femur of the residual limb. The outer surface of the titanium implant to be tested is attached to the bone tissue to form a titanium-bone interface.

[0007] Preferably, the rotary propulsion mechanism includes a linear slide, a rotary motor, and a brake. The linear slide includes a propulsion motor, a lead screw, and a slider. The output end of the propulsion motor is coaxially connected to the lead screw, and the slider is slidably connected to the lead screw. The rotary motor is mounted on the slider via a connecting plate. The connecting section of the detection rod is detachably coaxially connected to the output end of the rotary motor. The axis of the detection rod is parallel to the lead screw. The brake is located at the tail shaft of the rotary motor and is used to mechanically lock the rotary shaft system when the rotary motor stops and enters the silent acquisition stage.

[0008] Preferably, the brake is an electromagnetic spring brake that engages when powered off and disengages when powered on. The motion control unit includes an Arduino Uno R3 control module, a stepper motor driver, and a relay module. The Arduino Uno R3 control module is electrically connected to the relay module, which controls the power-on / off state of the brake. When the rotary motor needs to rotate, the Arduino Uno R3 controls the relay module to energize and release the brake. When the rotary motor reaches the target angle and enters the echo acquisition stage, the Arduino Uno R3 controls the relay module to de-energize and engage the brake, thereby using the friction of the brake to maintain the circumferential angular position of the detection rod.

[0009] Preferably, the preset trajectory includes: The linear slide moves the probe intermittently along the axial direction of the detection hole at a preset step distance. After each stop, the Arduino Uno R3 controls the relay module to energize and release the brake, and controls the rotary motor to rotate the probe around its own axis by one angular step distance. After the rotary motor reaches the target angle, the Arduino Uno R3 controls the relay module to de-energize and engage the brake, and then controls the rotary motor to enter the de-enabled state. The signal acquisition and processing unit then acquires the ultrasonic echo signal corresponding to the current axial position and circumferential angle. After acquisition, the Arduino Uno R3 controls the relay module to energize and release the brake, and controls the rotary motor to continue rotating to the next angular step distance. This process is repeated until the probe has rotated a total of 360° at the current axial position, completing the full circumferential scan at the current axial position. Then, the linear slide advances to the next axial step distance. At two adjacent axial positions, the rotation direction of the rotary motor is alternately set to be opposite.

[0010] Preferably, the outer wall of the probe mounting section is provided with a notch for mounting the PZT piezoelectric crystal probe, and the notch is provided with a removable cover.

[0011] Preferably, the signal acquisition and processing unit includes: Signal preprocessing module: performs filtering and noise reduction on the echo signal; Data processing module: Matches the echo signal with the axial position of the linear slide and the circumferential angle of the rotary motor to form axial and circumferential detection data of the titanium-bone interface.

[0012] According to another aspect of the present invention, a method for monitoring the health of an osseointegrated prosthesis interface includes: Before testing, one end of a plastic tube is fitted onto the outer wall of the test hole opening of the titanium implant to be tested, and a rubber sleeve is fitted onto the connection between the titanium implant and the plastic tube to detachably and seal the titanium implant and the plastic tube, forming a coupling agent retention cavity in the test hole opening area. The coupling agent retention cavity is used to contain the ultrasonic coupling agent, allowing the ultrasonic coupling agent to flow over the test surface of the PZT piezoelectric crystal probe and fill the gap inside the test rod to form a continuous ultrasonic propagation path.

[0013] Step S1: The rotating propulsion mechanism drives the detection rod to move axially from the port to the bottom in the detection hole along a preset trajectory to perform a forward scan, thereby obtaining echo signals from multiple detection points. During the movement of the detection rod driven by the rotating propulsion mechanism, ultrasonic waves are generated by the PZT piezoelectric crystal probe. The ultrasonic waves propagate axially along the deep detection section, are reflected by the reflector, and propagate radially along the deep detection section to the titanium-bone interface. After reflection, they form an echo and return along the original path. The echo is received by the PZT piezoelectric crystal probe. Step S2: The echo is processed by the signal acquisition and processing unit to form axial and circumferential detection data of the titanium-bone interface; Step S3: Based on the axial and circumferential detection data of the titanium-bone interface, extract the features of the echo at each detection point and construct the titanium-bone interface detection matrix; Step S4: Based on the titanium-bone interface detection matrix, and using the echo characteristics of the normal bone integration area as a benchmark, determine whether there are any abnormalities at the detection point locations.

[0014] Preferably, step S2 includes: Step S2.1: Filter and reduce noise in the echo signal; Step S2.2: Match the echo signal with the axial position of the linear slide and the circumferential angle of the rotary motor to form axial-circumferential detection data of the titanium-bone interface.

[0015] Preferably, step S3 includes: Extract the echo amplitude of the titanium-bone interface at each detection point. Dissemination time Echo energy and the center frequency of the spectrum A titanium-bone interface detection matrix was constructed; the position of each detection point is denoted as:

[0016]

[0017] in, This represents the detection point corresponding to the i-th axial position and the j-th circumferential angle; The axial position of the target detection point; The circumferential angle of the target detection point; The axial advance step distance of the slide table. The rotation sampling angle interval; The titanium-bone interface detection matrix is ​​represented as follows: .

[0018] Preferably, step S4 includes: Step S4.1: Based on the titanium-bone interface detection matrix, combined with the echo amplitude of the normal bone integration area. Dissemination time Echo energy and the center frequency of the spectrum For each detection point, scores are calculated for echo amplitude, propagation time, echo energy, and spectral center frequency, where:

[0019] In the formula, The score is given for the echo amplitude. A score based on the duration of transmission; A score for the echo energy; The score is given for the center frequency of the spectrum; Step S4.2: Calculate the comprehensive coupling evaluation index based on the scores of echo amplitude, propagation time, echo energy, and spectral center frequency. :

[0020] in, These are the weighting coefficients. ; Step S4.3: Comprehensive Coupling Evaluation Index Based on Each Detection Point To determine if there are any abnormalities at the detection point location, when When the value is less than the first threshold, the titanium-bone interface of the target detection point is considered to have good bonding; when... When the target detection point is located between the first threshold and the second threshold, it is judged as suspected insufficient binding; when When the value exceeds the second threshold, an anomaly is detected at the target detection point, and a warning message is output.

[0021] Preferably, step S5 is also included: When the detection rod moves to the bottom of the detection hole or the preset termination position, a reverse scan is performed via a rotating propulsion mechanism. Combining forward and reverse scans, consistency verification is conducted, and the consistency error is... for:

[0022] in, The comprehensive coupling evaluation index is obtained from the forward scan. This is the comprehensive coupling evaluation index obtained from the reverse re-examination. When... When the result is less than a preset threshold, the detection result is considered valid; when... If the value exceeds a preset threshold, the detection point is determined to be affected by coupling instability, mechanical vibration, or random noise. The detection point is then re-detected, its reliability is reduced, or it is removed in subsequent judgments.

[0023] Compared with the prior art, the present invention has the following beneficial effects: This invention uses a reflective sheet to convert ultrasonic waves that originally propagate along the axial path into those that propagate radially, thereby enabling the detection of the titanium-bone interface. Simultaneously, a rotating propulsion mechanism advances the detection rod axially and rotates circumferentially within the detection hole, collecting echo signals from each detection point. These signals are then converted into quantifiable evaluation results of the titanium-bone interface coupling, achieving quantitative detection and early warning of the healing degree, loosening risk, and cracking risk of titanium implants in osseointegrated prostheses. Attached Figure Description

[0024] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram showing the mating relationship between the test rod and the titanium implant to be tested. Figure 2 This is a cross-sectional view of the detection rod; Figure 3 This is a schematic diagram of the assembly of the detection rod and the rotary propulsion mechanism; Figure 4 A schematic diagram showing the separation of the sealing section for the detection rod installation segment; In the diagram, 1. Titanium implant to be tested; 2. Detection hole; 3. Detection rod; 4. Deep detection section; 5. PZT piezoelectric crystal probe; 6. Reflector; 7. Mounting section; 8. Clip; 9. Wire; 10. Connecting section; 11. Linear slide; 12. Rotary motor; 13. Propulsion motor; 14. Lead screw; 15. Slider; 16. Connecting plate; 17. Brake; 18. Plastic tube; 19. Rubber sleeve. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0026] Example 1: This embodiment provides a health monitoring device for the interface of osseointegrated prostheses, such as... Figure 1 As shown, it includes a detection rod 3, a rotary propulsion mechanism, a motion control unit, and a signal acquisition and processing unit; as Figure 2 and Figure 4As shown, the detection rod 3 includes a deep detection section 4, a probe mounting section 7, and a connecting section 10. Both the deep detection section 4 and the probe mounting section 7 are hollow structures. A PZT piezoelectric crystal probe 5 is installed in the probe mounting section 7. The PZT piezoelectric crystal probe 5 is connected to the single-channel interface of the phased array ultrasonic control equipment via a wire 9. The PZT piezoelectric crystal probe 5 is used to generate ultrasonic waves and receive echo signals. The ultrasonic waves generated by the PZT piezoelectric crystal probe 5 propagate collimated along the axial direction in the deep detection section 4. One end of the deep detection section 4 is connected to one end of the probe mounting section 7. A reflector 6 is provided at the other end of the deep detection section 4. The reflective surface of the reflector 6 completely covers the port of the deep detection section 4. The angle between the normal of the reflective surface and the axis of the deep detection section 4 is 45°. The detection segment 4 is inserted into the detection hole 2. The gap between the inner wall of the detection segment 4 and the inner wall of the detection hole 2 is filled with ultrasonic coupling agent to form the propagation path of ultrasonic waves. The connecting segment 10 is connected to the rotary propulsion mechanism, which drives the detection rod 3 to rotate around its own axis and move axially along the detection hole 2. The motion control unit controls the rotary propulsion mechanism to move according to a preset trajectory. The signal acquisition and processing unit processes the received echo signal to form axial-circumferential detection data of the titanium-bone interface. The detection hole 2 is set axially on one end face of the titanium implant 1 to be tested. The other end of the titanium implant 1 to be tested is implanted into the medullary cavity of the femur of the residual limb. The outer surface of the titanium implant 1 to be tested is attached to the bone tissue to form a titanium-bone interface.

[0027] Based on the above scheme, a detection hole 2 is set axially in the middle of the titanium implant 1 to be tested, and a detection rod 3 with a PZT piezoelectric crystal probe 5 and a 45° reflector 6 is inserted into the detection hole 2. The axial ultrasonic waves emitted by the PZT piezoelectric crystal probe 5 are deflected into radial ultrasonic waves by the 45° reflector 6, and then propagate through the wall thickness of the titanium implant to the peripheral titanium-bone interface. By axially advancing the linear slide 11 and rotating the rotary motor 12 circumferentially, continuous scanning detection of the titanium-bone interface can be achieved, and the degree of interface healing, coupling status, crack risk, and loosening risk can be determined based on the echo signal.

[0028] For example, the titanium implant 1 to be tested is a cylindrical titanium alloy implant rod, titanium rod, or titanium tube, with an outer diameter of 15 mm and a length of 150 mm. The detection hole 2 has a diameter of 8 mm and a depth of 130 mm. The detection rod 3 adopts a hollow tubular structure, including an insertion detection section 4, a probe mounting section 7, a connecting transition section, and a motor connection section 10. The insertion detection section 4 has an outer diameter of 7.6 mm, an inner diameter of 6 mm, and a length of 130 mm. The outer diameter of the detection rod 3 is smaller than the diameter of the detection hole 2, allowing the detection rod 3 to smoothly extend into the 8 mm diameter detection hole 2, and forming a unilateral radial coupling gap of approximately 0.2 mm between the outer wall of the detection rod 3 and the inner wall of the detection hole 2.

[0029] For example, the reflector 6 is made of 304 stainless steel and has an elliptical structure with a minor axis diameter of 7.6 mm and a major axis diameter of 7.6 mm. mm, thickness is 0.2 mm.

[0030] It is understandable that the phased array ultrasonic control equipment is the Liying 256 phased array equipment, and the PZT piezoelectric crystal probe 5 is connected to its single excitation / reception channel, with the same piezoelectric crystal completing the ultrasonic excitation and echo reception.

[0031] It should be noted that the ultrasound coupling agent is preferably physiological saline, glycerin, or other liquid coupling media that is well matched with the acoustic impedance of the titanium alloy, the probe 3 material, and the bone tissue. By allowing the coupling agent to enter the interior of the probe 3, an axial acoustic propagation path can be formed from the PZT piezoelectric crystal probe 5 to the 45° reflector 6; by filling the gap between the probe 3 and the detection hole 2 of the titanium implant with the coupling agent, a radial acoustic propagation path can be formed, reducing the acoustic energy attenuation caused by the air gap and improving the ultrasonic signal transmission efficiency.

[0032] In this embodiment, as Figure 3 As shown, the rotary propulsion mechanism includes a linear slide 11, a rotary motor 12, and a brake 17. The linear slide 11 includes a propulsion motor 13, a lead screw, and a slider 15. The output end of the propulsion motor 13 is coaxially connected to the lead screw. The slider 15 is slidably connected to the lead screw. The rotary motor 12 is mounted on the slider 15 via a connecting plate 16. The connecting section 10 of the detection rod 3 is detachably coaxially connected to the output end of the rotary motor 12. The axis of the detection rod 3 is parallel to the lead screw. The brake is installed at the tail shaft end of the rotary motor 12 and is used to mechanically lock the rotary axis system formed by the rotary motor 12 and the detection rod 3.

[0033] Based on the above scheme, the linear slide 11 is preferably a precision lead screw slide 14 with an effective stroke of not less than 150 mm and a repeatability better than 0.01 mm. The rotary motor 12 is mounted on the slider 15 of the linear slide 11 and fixed by a connecting plate 16. The motor connecting section 10 of the detection rod 3 is detachably connected to the output shaft of the rotary motor 12, preferably using a type B locating pin connection structure to ensure the coaxiality, angular synchronization, and assembly repeatability between the detection rod 3 and the rotary motor 12.

[0034] In this embodiment, the preset trajectory includes: The linear slide 11 drives the detector rod 3 to move intermittently in one direction along its axis at a preset step distance. During each intermittent stop phase of the linear slide 11, the Arduino Uno R3 controls the relay module to energize and release the brake 17, and controls the rotary motor 12 to drive the detector rod 3 to rotate around its own axis by a preset angle step distance. After the rotary motor 12 reaches the target angle, the Arduino Uno R3 controls the relay module to de-energize the brake 17, mechanically locking the output shaft of the rotary motor 12 and the detector rod 3; then the rotary motor 12 enters the de-enabled state, and the signal acquisition and processing unit acquires the ultrasonic echo signal at this axial position and circumferential angle. After the acquisition is completed, the brake 17 is energized and released again, and the rotary motor 12 continues to rotate to the next angle step distance. The above process is repeated until a total of 360° full circumferential scan is completed at the current axial position. Then the linear slide 11 advances to the next axial step distance, and at the adjacent axial position, the rotary motor 12 rotates in the opposite direction to accumulate a total of 360°.

[0035] Based on the above scheme, the motion control unit adopts an Arduino Uno R3 control module, and controls the axial pushing motion of the linear slide 11 and the forward and reverse rotation motion of the rotary motor 12 through a stepper motor driver. The axial pushing step of the linear slide 11 is preferably 1mm, and the rotation angle of the rotary motor 12 is a preset angle step, with a cumulative rotation angle of 360° at the axial position, and the angle positioning accuracy is preferably ±0.5°.

[0036] In this embodiment, the outer wall of the probe mounting section 7 is provided with a notch for mounting the PZT piezoelectric crystal probe 5, and a removable cover is provided at the notch.

[0037] Based on the above scheme, the probe mounting section 7 is designed as a detachable semi-sectional structure. Specifically, at the location where the PZT piezoelectric crystal probe 5 is mounted on the detection rod 3, the rod body is partially divided into two cooperating parts, one of which forms a probe receiving groove. During installation, the PZT piezoelectric crystal probe 5 is inserted into the probe receiving groove, ensuring that the PZT piezoelectric crystal probe 5, the hollow acoustic propagation channel inside the detection rod 3, and the front reflector 6 are aligned axially. The cover is then replaced. A clip 8 is provided on the outside of the probe mounting section 7, which engages with the corresponding position on the detection rod 3 to assist in fixing the PZT piezoelectric crystal probe 5 and the cover structure. M1 bolts and nuts are used for tightening to prevent the probe from loosening, shifting, or falling off during the advancement or rotation of the detection rod 3. An outlet hole is provided on the outer wall of the mounting section 7, through which the wire 9 connected to the PZT piezoelectric crystal probe 5 passes and connects to the phased array ultrasonic control equipment.

[0038] In this embodiment, the signal acquisition and processing unit includes: Signal preprocessing module: performs filtering and noise reduction on the echo signal; Data processing module: Matches the echo signal with the axial position of the linear slide 11 and the circumferential angle of the rotary motor 12 to form axial-circumferential detection data of the titanium-bone interface.

[0039] Working principle: In this embodiment, a plastic tube 18 is sleeved on the outer side of the opening end of the detection hole 2 of the titanium implant 1 to be tested, and one end of the plastic tube 18 is sleeved on the outer wall of the titanium implant 1 to be tested; a rubber sleeve 19 is sleeved at the connection between the titanium implant 1 to be tested and the plastic tube 18, so that one end of the rubber sleeve 19 covers the outer wall of the titanium implant 1 to be tested and the other end covers the outer wall of the plastic tube 18, thereby detachably and sealingly connecting the titanium implant 1 to be tested and the plastic tube 18, and forming a coupling agent retention cavity in the opening area of ​​the detection hole 2. Ultrasonic coupling agent is injected into the hollow channel of the plastic tube 18, the detection hole 2 and the detection rod 3, so that the level of the coupling agent is higher than the detection surface of the PZT piezoelectric wafer probe 5, and the coupling agent fills the gap inside the detection rod 3, thereby forming a continuous ultrasonic propagation path from the detection surface of the PZT piezoelectric wafer probe 5 to the reflector 6, the inner wall of the detection hole 2 and the titanium-bone interface.

[0040] Subsequently, the detection rod 3, with the PZT piezoelectric crystal probe 5 already installed, is connected to the output of the rotary motor 12, so that the reflective sheet 6 at the front end of the detection rod 3 faces the inside of the titanium implant detection hole 2, and the PZT piezoelectric crystal probe 5, the hollow channel of the detection rod 3, and the 45° reflective sheet 6 are aligned axially. The Arduino Uno R3 control module is activated to return the linear slide 11 to its initial position and complete the zeroing of the angle of the rotary motor 12. The phased array ultrasonic control device is activated to apply an excitation signal to the PZT piezoelectric crystal probe 5 through a single channel.

[0041] During testing, the PZT piezoelectric crystal probe 5 generates ultrasonic pulses under the excitation of the phased array ultrasonic control device. The ultrasonic waves propagate axially through the coupling agent within the hollow channel of the detection rod 3 to the reflector 6, where they are reflected and converted into radial ultrasonic waves. These radial ultrasonic waves are transmitted through the coupling agent between the outer wall of the detection rod 3 and the inner wall of the detection hole 2 of the titanium implant to the inner wall of the titanium implant, and further propagate through the thickness of the titanium implant wall to the titanium-bone interface. The echo reflected from the titanium-bone interface returns along the original path, is redirected again by the reflector 6, and is received by the same PZT piezoelectric crystal probe 5.

[0042] During the testing process, the Arduino Uno R3 controls the linear slide 11 to advance the probe 3 in 1mm increments. After each 1mm advance, the linear slide 11 stops moving, and the Arduino Uno R3 controls the relay module to energize and release the brake 17. The rotary motor 12 then drives the probe 3 to rotate around its own axis by a preset angle increment. When the rotary motor 12 reaches the target angle, the Arduino Uno R3 controls the relay module to de-energize the brake 17, mechanically locking the output shaft of the rotary motor 12 and the probe 3. Subsequently, the rotary motor 12 enters a de-enabled state, and the signal acquisition and processing unit acquires the ultrasonic echo signals at this axial position and circumferential angle. After acquisition, the Arduino Uno R3 controls the relay module to energize and release the brake, and controls the rotary motor to continue rotating to the next angle increment. This process is repeated until the probe has rotated a cumulative 360° at the current axial position, after which the linear slide 11 advances to the next axial increment.

[0043] At adjacent axial detection positions, the rotation direction of the rotary motor 12 alternates: the first detection position rotates 360° forward, the second detection position rotates 360° in the opposite direction, and the third detection position rotates 360° forward again, and so on. This alternating forward and reverse rotation method avoids the signal wire 9 from becoming entangled due to continuous unidirectional rotation and improves the stability and repeatability of the detection process.

[0044] When the linear slide 11 moves the detection rod 3 forward to the preset detection distance, preferably 100mm, it reaches the end detection area of ​​the titanium implant detection hole 2 or the preset endpoint position. Then, the linear slide 11 is controlled to move in the reverse direction, causing the detection rod 3 to return 100mm along the original path. During the return process, reverse scanning and re-inspection can continue according to the same timing and rotation logic, or it can quickly return to the initial position for the next round of inspection.

[0045] The signal acquisition and processing unit filters and reduces the noise of the acquired ultrasonic echo signals, and correlates the processed echo signals with the corresponding axial position of the slide table and the 12 circumferential angle of the rotary motor to form an axial-circumferential detection data map of the titanium-bone interface. Based on the amplitude, arrival time, spectral characteristics, energy attenuation, and waveform changes of the echo signals, it determines whether there is poor osseointegration, local debonding, interfacial gap, bone resorption, cracks, or fatigue damage to the titanium implant at the titanium-bone interface.

[0046] The data processing module can extract the interface echo amplitude ratio, propagation time difference, echo energy attenuation coefficient, spectral center frequency offset, and continuity parameters of adjacent detection points as evaluation indicators for the titanium-bone interface coupling status. Based on the evaluation indicators, the titanium-bone interface status can be classified into levels of good bonding, suspected insufficient bonding, local debonding, obvious gaps, and risk of cracking or loosening.

[0047] When the test results show abrupt changes in echo amplitude, abnormal propagation time, abnormal spectrum, or waveform distortion at a certain axial position and circumferential angle, the system marks that location as a suspected abnormal area and outputs the bonding status of the titanium-bone interface, the location of the abnormality, the risk level, and warning information. The warning information can be used to prompt doctors or users to conduct further examinations, reduce the weight-bearing load on the prosthesis, adjust rehabilitation training programs, or take appropriate clinical interventions, thereby reducing the risk of loosening, dislodgement, or failure of the osseointegrated prosthesis titanium implant.

[0048] Example 2: This embodiment provides a method for monitoring the health of the osseointegrated prosthesis interface, applied to the device in Embodiment 1. The method includes: Before testing, the end of the plastic tube is placed on the outside of the titanium implant to be tested, and the rubber tube is sleeved on the outside of the plastic tube, so that the two form a detachable coupling agent retention structure in the detection hole opening area; ultrasonic coupling agent is injected into the detection hole, the hollow channel of the detection rod and the coupling agent retention structure, so that the ultrasonic coupling agent overflows the detection surface of the PZT piezoelectric crystal probe and fills the gap between the inside of the detection rod and the outer wall of the detection rod and the inner wall of the detection hole, so as to form a continuous ultrasonic propagation path.

[0049] Step S1: The rotating propulsion mechanism drives the detection rod to move from the port to the bottom in the detection hole along a preset trajectory to perform a forward scan, thereby obtaining echo signals from multiple detection points. During the movement of the detection rod driven by the rotating propulsion mechanism, ultrasonic waves are generated by the PZT piezoelectric crystal probe. The ultrasonic waves propagate axially along the deep detection section, are reflected by the reflector, and propagate radially along the deep detection section to the titanium-bone interface. After reflection, they form an echo and return along the original path. The echo is received by the PZT piezoelectric crystal probe. At each axial detection position, step S1 includes: Step S1.1: Control the brake to be energized and released, so that the output shaft of the rotary motor is in a rotatable state; Step S1.2: Control the rotary motor to drive the detection rod to rotate by a preset angle step; Step S1.3: After the rotary motor reaches the target circumferential angle, the control brake is de-energized and the brake is engaged, so that the circumferential position of the detection rod is mechanically locked. Step S1.4: Control the rotary motor to enter the de-enabled state and collect the ultrasonic echo signals at the current axial position and current circumferential angle; Step S1.5: Repeat steps S1.1 to S1.4 until the detection rod has rotated a total of 360° in the current axial position, and then control the linear slide to advance to the next axial step.

[0050] Step S2: The echo is processed by the signal acquisition and processing unit to form axial and circumferential detection data of the titanium-bone interface; Step S3: Based on the axial and circumferential detection data of the titanium-bone interface, extract the features of the echo at each detection point and construct the titanium-bone interface detection matrix; Step S4: Based on the titanium-bone interface detection matrix, and using the echo characteristics of the normal bone integration area as a benchmark, determine whether there are any abnormalities at the detection point locations.

[0051] In this embodiment, step S2 includes: Step S2.1: Filter and reduce noise in the echo signal; Step S2.2: Match the echo signal with the axial position of the linear slide and the circumferential angle of the rotary motor to form axial-circumferential detection data of the titanium-bone interface.

[0052] In this embodiment, step S3 includes: Extract the echo amplitude of the titanium-bone interface at each detection point. Dissemination time Echo energy and the center frequency of the spectrum A titanium-bone interface detection matrix was constructed; the position of each detection point is denoted as:

[0053]

[0054] in, This represents the detection point corresponding to the i-th axial position and the j-th circumferential angle; The axial position of the target detection point; The circumferential angle of the target detection point; The axial advance step distance of the slide table; The rotation sampling angle interval; The titanium-bone interface detection matrix is ​​represented as follows: .

[0055] In this embodiment, step S4 includes: Step S4.1: Based on the titanium-bone interface detection matrix, combined with the echo amplitude of the normal bone integration area. Dissemination time Echo energy and the center frequency of the spectrum For each detection point, scores are calculated for echo amplitude, propagation time, echo energy, and spectral center frequency, where:

[0056] In the formula, The score is given for the echo amplitude. A score based on the duration of transmission; A score for the echo energy; The score is given for the center frequency of the spectrum; Step S4.2: Calculate the comprehensive coupling evaluation index based on the scores of echo amplitude, propagation time, echo energy, and spectral center frequency. :

[0057] in, These are the weighting coefficients. ; Step S4.3: Comprehensive Coupling Evaluation Index Based on Each Detection Point To determine if there are any abnormalities at the detection point location, when When the value is less than the first threshold, the titanium-bone interface of the target detection point is considered to have good bonding; when... When the target detection point is located between the first threshold and the second threshold, it is judged as suspected insufficient binding; when When the value exceeds the second threshold, it is determined that the target detection point has the risk of debonding, gaps, cracks or loosening, and a warning message is output.

[0058] The first and second thresholds were determined through calibration experiments. Under the condition that the detection system parameters, probe parameters, coupling agent state, weighting coefficients, and scanning parameters remained consistent, calibration samples were collected from normal bone integration areas and areas with known interface abnormalities, and the comprehensive coupling evaluation index for each detection point was calculated.

[0059] When the comprehensive coupling evaluation index set is in normal condition When the distribution approximately follows a normal distribution, let the mean of the comprehensive coupling evaluation index under normal conditions be . The standard deviation is They can be represented as:

[0060]

[0061] Then the first threshold Second threshold They can be represented as:

[0062]

[0063] in, The number of normal calibration test points, The first under normal conditions k The comprehensive coupling evaluation index of each calibration detection point and These are the sample mean and sample standard deviation, respectively.

[0064] When the comprehensive coupling evaluation index under normal conditions does not conform to a normal distribution, the first threshold and the second threshold can be taken as the 95th percentile and the 99th percentile of the comprehensive coupling evaluation index under normal conditions, respectively:

[0065]

[0066] And satisfy:

[0067] in, This represents the 95th percentile operation. This represents the 99th percentile operation. This represents the sample set of comprehensive coupling evaluation indices obtained under normal osseointegration conditions, provided that the detection system parameters, probe parameters, coupling state, scanning parameters, and weighting coefficients remain consistent.

[0068] When calibration samples have known debonding, gaps, cracks, or loosening conditions, the second threshold can also be determined based on the classification sensitivity and specificity of normal and abnormal samples. When the detection system parameters, weighting coefficients, or detection object type change, recalibration is performed and the first and second thresholds are updated.

[0069] In this embodiment, step S5 is also included: When the detection rod moves to the bottom of the detection hole or the preset termination position, a reverse scan is performed by a rotating propulsion mechanism. Combining the forward and reverse scans, consistency verification is conducted, and the consistency error is:

[0070] in, The comprehensive coupling evaluation index is obtained from the forward scan. The comprehensive coupling evaluation index is obtained from the reverse re-examination. This represents the consistency error between forward and reverse scans.

[0071] Preset consistency threshold This was determined through repeatability calibration tests. Under the condition that the detection system parameters, probe parameters, coupling agent state, scanning parameters, and signal processing parameters remained consistent, multiple forward and reverse scans were performed on a calibration specimen with a stable interface state to obtain the consistency error set under stable repeatability testing conditions. .

[0072] When the consistency error approximately follows a normal distribution, let the mean of the comprehensive coupling evaluation index under normal conditions be... The standard deviation is They can be represented as:

[0073]

[0074] The preset consistency threshold can be:

[0075] in, To determine the effective number of calibration test points under stable and repeated testing conditions, The first under normal conditions k Consistency error of forward and reverse scanning at each calibration test point and These are the mean and sample standard deviation of the consistency error, respectively.

[0076] When consistency errors do not follow a normal distribution, the preset consistency threshold can be taken as the 99th percentile of the consistency error set:

[0077] in, This represents the 99th percentile operation. This means that, under the condition that the detection system parameters, probe parameters, coupling state, scanning parameters and weighting coefficients are kept consistent, multiple forward and reverse scans are performed on the calibration specimen with stable interface state to obtain the consistency error set under stable repeated detection conditions.

[0078] when When the forward and reverse scanning results of the detection point are consistent, the detection result is considered valid; when If the detection point is determined to be affected by changes in coupling state, mechanical vibration, positioning error, or random noise, the detection point should be re-detected, its results should be made less reliable, or it should be removed in subsequent state judgments.

[0079] It should be noted that when ultrasound propagates between titanium implants, coupling agents, and bone tissue, its interface reflection characteristics are related to the acoustic impedance of the medium. satisfy:

[0080] When ultrasound waves propagate from a titanium implant to bone tissue or areas of interface abnormality, the interface acoustic pressure reflection coefficient r It can be represented as:

[0081] Interface sound intensity reflection coefficient It can be represented as:

[0082] in, The equivalent acoustic impedance of the titanium implant side. Equivalent acoustic impedance for abnormal areas of bone tissue or interfaces. The density of the medium; The speed at which ultrasound propagates in this medium is denoted as .

[0083] Under conditions where the detection system gain, probe sensitivity, and propagation path are relatively stable, the amplitude of the interface reflection echo is related to the sound pressure reflection coefficient, which can be expressed as:

[0084] in, For the first i The first axial position, the first j The echo amplitude at each detection point at a circumferential angle The amplitude of the ultrasonic wave incident on the interface at the detection point. The sound pressure reflection coefficient at this detection point. This is a proportionality coefficient related to probe sensitivity, system gain, and coupling efficiency. The equivalent attenuation coefficient in the propagation path, Let e ​​be the equivalent propagation distance of the ultrasonic wave from the probe to the interface, and e be the natural constant.

[0085] As can be seen from the above formula, when there are air gaps, debonding, bone resorption, or cracks at the titanium-bone interface, the local equivalent acoustic impedance changes, thus affecting the sound pressure reflection coefficient. The change causes the echo amplitude to... It may exhibit enhancement, weakening, or mutation.

[0086] Furthermore, the echo energy is related to the sound intensity reflection coefficient. i The first axial position, the first j The echo energy at each detection point at a circumferential angle can be expressed as:

[0087] in, This refers to the echo energy received at that detection point. The acoustic energy incident on the interface. This is the sound intensity reflection coefficient at the detection point. This is a proportionality coefficient related to the system's acquisition gain, probe conversion efficiency, and coupling efficiency. (Exponential term) This indicates the energy attenuation during the round-trip propagation of ultrasound.

[0088] For the actual acquired discrete echo signal, let the filtered echo signal be... Then the echo amplitude and echo energy can be extracted as follows:

[0089]

[0090] in, This represents the sampling time window where the titanium-bone interface echo is located. Echo amplitude reflects the intensity of interface reflection, echo energy It reflects the overall energy level of the reflected signal within that time window.

[0091] Furthermore, propagation time primarily reflects the length of the ultrasonic wave propagation path, the equivalent sound velocity, and changes in the interface position. i The first axial position, the first j The arrival time of the echo at each circumferential angle detection point can be expressed as:

[0092] in, For echo arrival time, This represents the equivalent propagation distance of the ultrasonic wave from the probe to the interface. This is the equivalent speed of sound along the detection path. This includes system circuit delay, probe response delay, and acquisition delay.

[0093] Therefore, transmission time The echo arrival time is not determined solely by the interface reflection coefficient, but rather by the propagation path, equivalent sound velocity, and interface location. When gaps, debonding, cracks, or bone resorption exist at the titanium-bone interface, the local propagation path or equivalent sound velocity may change, leading to a shift in the echo arrival time. For the filtered discrete echo signal, the echo arrival time is determined using the peak value method.

[0094]

[0095] in, This refers to the time sequence number of the sampling point corresponding to the peak value of the interface echo. The sampling frequency.

[0096] Furthermore, the spectral characteristics are mainly used to reflect the changes in the frequency components of ultrasound waves in the propagation path composed of titanium implants, coupling agents, bone tissue, and the titanium-bone interface.

[0097] It should be noted that ultrasound waves at the titanium-bone interface mainly undergo reflection, transmission, mode conversion, and multiple reflections near the interface; while scattering, absorption attenuation, and frequency-selective attenuation mainly occur within the volumetric medium such as the titanium implant, bone tissue, and coupling agent. Therefore, the spectral characteristics in this invention do not solely represent the interface reflection coefficient, but rather characterize the spectral changes of ultrasound waves after being affected by interface reflection / transmission, mode conversion, multiple reflections, and the combined effects of scattering and attenuation by the volumetric medium during propagation. The filtered echo signal... Perform Fourier transform:

[0098] The center frequency of the spectrum at this detection point can then be expressed as:

[0099] For discrete spectra, the above equation can be written as:

[0100] in, The center frequency of the spectrum; The echo signal spectrum; For the first q The frequency value corresponding to each frequency point; To analyze the frequency band range; For Fourier transform operators; This is a frequency variable, measured in Hertz.

[0101] In this invention, the interface reflection coefficient is primarily used to characterize the acoustic impedance difference between the titanium implant and bone tissue or abnormal interface regions. It has a direct correlation with the echo amplitude and energy of the target echo at the titanium-bone interface. Propagation time is not directly determined by the interface reflection coefficient, but rather serves as an auxiliary characteristic reflecting the length of the ultrasound propagation path, the equivalent sound velocity along the propagation path, and changes in the interface position. The spectral center frequency does not solely characterize the interface reflection coefficient, but rather serves as an auxiliary characteristic reflecting the combined effects of interface reflection and transmission, mode conversion, multiple reflections, volumetric scattering, absorption attenuation, and frequency-selective attenuation. Therefore, this invention enables a comprehensive evaluation of the degree of healing, coupling state, debonding, gaps, cracks, and loosening risk at the titanium-bone interface.

[0102] The present invention also provides a skeletal integrated prosthesis interface health monitoring system, which can be implemented by executing the process steps of the skeletal integrated prosthesis interface health monitoring method. That is, those skilled in the art can understand the skeletal integrated prosthesis interface health monitoring method as a preferred embodiment of the skeletal integrated prosthesis interface health monitoring system.

[0103] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0104] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0105] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A health monitoring device for the interface of an osseointegrated prosthesis, characterized in that, It includes a detection rod, a rotary propulsion mechanism, a motion control unit, and a signal acquisition and processing unit; The detection rod includes a deep detection section, a probe mounting section, and a connecting section. Both the deep detection section and the probe mounting section are hollow structures. A PZT piezoelectric crystal probe is installed in the probe mounting section. The PZT piezoelectric crystal probe is connected to the single-channel interface of the phased array ultrasonic control equipment via a wire. The PZT piezoelectric crystal probe is used to generate ultrasonic waves and receive echo signals. The ultrasonic waves generated by the PZT piezoelectric crystal probe propagate collimated along the axial direction in the deep detection section. One end of the deep detection section is connected to one end of the probe mounting section, and a reflective sheet is provided at the other end of the deep detection section. The reflective surface of the reflective sheet completely covers the port of the deep detection section. The angle between the normal of the reflective surface and the axis of the deep detection section is 45°. The deep detection section is used to be inserted into the detection hole along the axis. The interior of the deep detection section and the gap between the outer wall of the deep detection section and the inner wall of the detection hole are filled with ultrasonic coupling agent to form the propagation path of ultrasonic waves. The connecting section is connected to the rotary propulsion mechanism, which is used to drive the detection rod to rotate around its own axis and move axially along the detection hole. The motion control unit is used to control the rotary propulsion mechanism to move according to a preset trajectory. The signal acquisition and processing unit is used to process the received echo signal to form axial and circumferential detection data of the titanium-bone interface. The detection hole is axially disposed on one end face of the titanium implant to be tested, and the other end of the titanium implant to be tested is implanted into the medullary cavity of the femur of the residual limb. The outer surface of the titanium implant to be tested is attached to the bone tissue to form a titanium-bone interface. The following method is used: Step S1: The rotating propulsion mechanism drives the detection rod to move axially from the port to the bottom in the detection hole along a preset trajectory to perform a forward scan, thereby obtaining echo signals from multiple detection points. During the movement of the detection rod driven by the rotating propulsion mechanism, ultrasonic waves are generated by the PZT piezoelectric crystal probe. The ultrasonic waves propagate axially along the deep detection section, are reflected by the reflector, and propagate radially along the deep detection section to the titanium-bone interface. After reflection, they form an echo and return along the original path. The echo is received by the PZT piezoelectric crystal probe. Step S2: The echo is processed by the signal acquisition and processing unit to form axial and circumferential detection data of the titanium-bone interface; Step S3: Based on the axial and circumferential detection data of the titanium-bone interface, extract the features of the echo at each detection point and construct the titanium-bone interface detection matrix; Step S4: Based on the titanium-bone interface detection matrix, and using the echo characteristics of the normal bone integration area as a benchmark, determine whether there are any abnormalities at the detection point locations; wherein, step S4 includes: Step S4.1: Based on the titanium-bone interface detection matrix, combined with the echo amplitude of the normal bone integration area. Dissemination time Echo energy and the center frequency of the spectrum For each detection point, scores are calculated for echo amplitude, propagation time, echo energy, and spectral center frequency, where: In the formula, The score is given for the echo amplitude. A score based on the duration of transmission; A score for the echo energy; The score is given for the center frequency of the spectrum; Step S4.2: Calculate the comprehensive coupling evaluation index based on the scores of echo amplitude, propagation time, echo energy, and spectral center frequency. : in, These are the weighting coefficients. ; Step S4.3: Comprehensive Coupling Evaluation Index Based on Each Detection Point To determine if there are any abnormalities at the detection point location, when When the value is less than the first threshold, the titanium-bone interface of the target detection point is considered to have good bonding; when... When the target detection point is located between the first threshold and the second threshold, it is judged as suspected insufficient binding; when When the value exceeds the second threshold, an anomaly is detected at the target detection point, and a warning message is output.

2. The apparatus according to claim 1, characterized in that, The rotary propulsion mechanism includes a linear slide and a rotary motor. The linear slide includes a propulsion motor, a lead screw, and a slider. The output end of the propulsion motor is coaxially connected to the lead screw. The slider is slidably connected to the lead screw. The rotary motor is mounted on the slider through a connecting plate. The connecting section of the detection rod is detachably coaxially connected to the output end of the rotary motor. The axis of the detection rod is parallel to the lead screw.

3. The apparatus according to claim 2, characterized in that, The preset trajectory includes: The linear slide moves the detection rod unidirectionally and intermittently along its axis with a preset step distance. During each intermittent stop phase of the linear slide, the rotary motor drives the detection rod to rotate 360° around its own axis to complete a full circumferential scan at the current axial position through the reflective sheet at the end of the detection rod. At two adjacent axial positions, the rotation direction of the rotary motor is alternately set to be opposite.

4. The apparatus according to claim 1, characterized in that, The outer wall of the probe mounting section is provided with a notch for mounting the PZT piezoelectric wafer probe, and the notch is provided with a removable cover.

5. The apparatus according to claim 1, characterized in that, The signal acquisition and processing unit includes: Signal preprocessing module: performs filtering and noise reduction on the echo signal; Data processing module: Matches the echo signal with the axial position of the linear slide and the circumferential angle of the rotary motor to form axial and circumferential detection data of the titanium-bone interface.

6. The apparatus according to claim 1, characterized in that, Step S2 includes: Step S2.1: Filter and reduce noise in the echo signal; Step S2.2: Match the echo signal with the axial position of the linear slide and the circumferential angle of the rotary motor to form axial-circumferential detection data of the titanium-bone interface.

7. The apparatus according to claim 1, characterized in that, Step S3 includes: Extract the echo amplitude of the echo at each detection point Dissemination time Echo energy and the center frequency of the spectrum A titanium-bone interface detection matrix was constructed; the position of each detection point is denoted as: in, This represents the detection point corresponding to the i-th axial position and the j-th circumferential angle; The axial position of the target detection point; The circumferential angle of the target detection point; The axial advance step distance of the slide table. The rotation sampling angle interval; The titanium-bone interface detection matrix is ​​represented as follows: .

8. The apparatus according to claim 1, characterized in that, The method further includes step S5: When the detection rod moves to the bottom of the detection hole or the preset termination position, a reverse scan is performed via a rotating propulsion mechanism. Combining forward and reverse scans, consistency verification is conducted, and the consistency error is... for: in, The comprehensive coupling evaluation index is obtained from the forward scan. The comprehensive coupling evaluation index obtained from reverse re-examination; when When the value is less than a preset threshold, the detection result is considered valid; when... If the value exceeds the preset threshold, a re-detection or a reduction in the discrimination weight will be performed.

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