190 results about "Bone marrow cavity" patented technology

An intraosseous access device can include a constant-torque spring assembly disposed in a housing, a drive shaft extending from the housing, and an intraosseous needle coupled to the drive shaft configured to provide intraosseous access to a medullary cavity of a patient. A method of using an intraosseous access device can include inserting a distal end of the intraosseous needle through skin at an insertion site of a patient and applying a contacting force to a bone beneath the insertion site with the distal end of the intraosseous needle. The contacting force can initiate a winding of a ribbon of the constant-torque spring assembly from an output spool onto a storage spool, thereby initiating drilling rotation of the intraosseous needle. The method can further include drilling through the bone until the intraosseous needle enters a medullary cavity of the patient.

An angled intraosseous access system includes a guide assembly including a guide block and a guide plate. The system can include a driver and a needle assembly rotatably coupled thereto. The guide assembly is configured to align the needle at a predetermined angle relative to the medullary cavity. Advantageously, the angled needle of the intraosseous access system can mitigate pain during infusion and mitigate backwalling.

This invention relates to an ultrasonic bone scalpel and an ultrasonic cutting device, belonging to the field of medical device technology. The ultrasonic bone scalpel is used to cut bone tissue from within the medullary cavity, and includes an ultrasonic scalpel body and a retaining assembly. The ultrasonic scalpel body includes a handle and a cutting head mounted on one end of the handle. The retaining assembly includes a pressure bladder mounted on the handle, with the pressure bladder and cutting head arranged radially opposite each other along the handle. The pressure bladder is capable of expanding or contracting. The ultrasonic bone scalpel provided by this invention utilizes the expansion of the pressure bladder to provide continuous cutting pressure based on the cutting action of the ultrasonic scalpel body, reducing the cutting wound on soft tissue, thereby protecting soft tissue while satisfying bone tissue cutting requirements. Furthermore, because this ultrasonic bone scalpel cuts from the inside out of the medullary cavity, it avoids external damage to soft tissue, thus reducing the cutting wound on soft tissue and further protecting it. Therefore, when the cutting wound on soft tissue is reduced, the risk of intraoperative infection is correspondingly reduced, and the healing time is shortened.

A method for preparing an intramedullary canal of a patient's bone during a surgical procedure to implant a surgical component. The method comprises identifying a starting point on a distal end of the bone, preparing the bone using a device comprising a cutting head with a plurality of helical cutting flutes and one or more features formed into at least one of the helical cutting flutes, and visually confirming the position of at least one indicating feature within the bone.

The invention relates to a tibial plateau prosthesis. The tibial plateau prosthesis mainly comprises a tibial spacer, a tibial plateau and a sleeve. The tibia gasket is provided with a first fixing block and three arc-shaped holes, and movable second fixing blocks are arranged in the holes. The tibial plateau comprises a plateau support with open holes and a shell, and the open holes are formed in the side portion and the bottom of the shell. The screw penetrates through the gasket and the platform support to be inserted into the shell, and outer threads of the screw are meshed with inner threads of the sleeve. The sleeve moves upwards and extends out of the side hole of the shell through a hinged connecting rod system to penetrate into the medullary cavity to enhance fixation. A spring is arranged in the screw to drive the first pushing part and can be matched with the sleeve to prevent downward movement; and meanwhile, the second pushing part in the screw can extend into the medullary cavity from the bottom through threads. The design realizes multidirectional fixation and improves the stability of the prosthesis.

The invention discloses a drilling device for an operation, and relates to the technical field of operation drilling. Comprising a drilling handpiece, a drilling part is installed on the drilling handpiece, and the drilling part is used for drilling in bone; a crumple limiting piece is mounted on the drilling handheld piece; the collapse limiting piece is used for preventing excessive downward pressure; a lifting adapter is mounted on the drilling part; a pushing part is mounted on the lifting adapter; the propelling piece is used for limiting the drilling depth; the propelling part is matched with the lifting adapting part, so that the time of elastic retraction intervention of the crumple limiting part can be controlled, and when bone drilling is carried out in the earlier stage, a doctor can have good downward pressure, and the drilling efficiency is guaranteed; the problems that an existing drilling device for the operation is not convenient to automatically control to reduce the drilling pressure when approaching to drill through bone substances, and meanwhile is not convenient to prevent flushing from damaging a marrow cavity are solved.

The invention discloses a three-section thighbone retrograde intramedullary nail, relates to the field of medical instruments, and provides a detachable and assembled three-section thighbone retrograde intramedullary nail aiming at the problems that an existing thighbone medial condyle retrograde intramedullary nail is poor in adaptability and insufficient in fixing strength. A main nail body of the intramedullary nail is composed of a head section, a middle section and a tail section, original spiral nested structures are adopted at the joints of the sections, and the three sections are tightly connected to form the complete and high-strength intramedullary nail by matching with the hollow interior design and penetrating a titanium cable into a medullary cavity for tightening and automatically rotating and matching the head section and the middle section of the main nail body. And medullary cavity structures and fracture types of different patients can be accurately matched. Compared with a traditional intramedullary nail, the intramedullary nail has the advantages that mounting convenience and structural stability are remarkably improved, intraoperative adjustment time can be shortened, the risk of injury to a medullary cavity of a patient is reduced, and an innovative solution is provided for personalized treatment of distal femur fractures.

The invention relates to the technical field of orthopedic biomedical treatment, in particular to a proximal humerus fracture intramedullary bone cement supporting rod. The bone fracture plate comprises a bone fracture plate body, a plurality of first connecting holes and a plurality of second connecting holes are formed in one side of the bone fracture plate body in a penetrating mode, and solid bone nails are arranged in the first connecting holes. According to the device, bone cement is injected into a marrow cavity from an injection molding channel and an injection molding opening and then solidified into a rod body, the marrow cavity space is tightly filled, supporting structures are synchronously formed on the inner side and the outer side of the humerus through cooperation of a bone fracture plate and a bone cement supporting rod in the marrow cavity space, and therefore stress generated when arms of a patient move is evenly dispersed on the two sides of the humerus; the fixing stability is remarkably improved, the risk of internal fixation failure such as steel plate displacement and screw cutting is effectively reduced, and the bone cement supporting rods can further prevent displacement of fracture blocks, promote fracture repair, relieve extrusion and friction of surrounding tissue of a filling position, reduce inflammatory response and postoperative pain and improve the rehabilitation comfort of a patient.

The present invention relates to a bone plate for connecting fractured bones. The bone plate includes a trunk and a tail connected to one end of the trunk, and the trunk includes a raised abdomen and a flat back connected to the abdomen. The trunk is implanted in the bone marrow cavity of the bone and partially shields the radial cross-section of the bone marrow cavity. The tail is fixed to the bone. The abdomen and the back both abut the crack of the broken bone. The present invention provides a trunk including a raised abdomen and a flat back, and the abdomen and the back abut the crack of the broken bone, so that the bone plate stably connects the fractured bones together, and the bone plate will not deform significantly with the deformation of the bone. At the same time, because the trunk partially shields the radial cross-section of the bone marrow cavity, the bone marrow cavity is not completely blocked, which helps to transport nutrients in the bone marrow. In addition, the surgical wound of the bone plate of the present invention is small.

The invention provides an extramedullary 3D printing composite intramedullary fixing bone end broach system, and relates to the technical field of medical instruments. Comprising a bone prosthesis and a fixing system, and the fixing system comprises a broach which is arranged at one end of the bone prosthesis and is fixed in a medullary cavity through bone cement; the fixing piece is arranged at the end, close to the broach, of the bone prosthesis and makes contact with the host bone, and the contact face is a 3D printing interface; the preset part is used for replacing the fixing part to make contact with the host bone in the prosthesis mounting operation. According to the fixing system, the broach, the fixing part and the preset part are used in cooperation, bone cement in a medullary cavity is fixed through the broach, and 3D interface fixing is adopted through the fixing part, so that the bone prosthesis has good bone conductivity and mechanical stability in a long term and a short term; and the influence on bone ingrowth caused by the fact that bone cement falls into a 3D contact interface of the fixing piece in a prosthesis installation operation is avoided.

To provide a fracture treatment fixation device for femoral fractures, enabling further reliable treatment of fractures of proximal femur.SOLUTION: A fracture treatment fixation device for treating femoral fractures includes: an intramedullary nail to be inserted into a femoral cavity; a lag screw disposed to penetrate the intramedullary nail diagonally upward and entering a femoral head and a femoral neck; an anterior wall plate to be applied to an anterior wall of a femoral trochanter; and an anterior wall plate fixation pin disposed to penetrate the intramedullary nail and secure the anterior wall plate to the anterior wall of the femoral trochanter.SELECTED DRAWING: Figure 1

The invention provides a femoral stem prosthesis. The femoral stem prosthesis comprises a femoral stem, an expansion component and a sleeve. The femoral stem is composed of an upper stem body and a replaceable lower stem body, and threads are arranged in the femoral stem. The expansion part is located in the upper handle body and comprises a screw, a rotating disc and a multi-layer pushing structure. The screws are connected with the upper and lower handle bodies through threads; and the turntable is in threaded engagement with the screw and can drive the first pushing part along the first guide rail during rotation. Ratchets are arranged in the rail component and meshed with the pawls of the second pushing part, and an open hole is formed in the side of the second pushing part. And the sleeve is linked with the expansion component through the fifth pushing part, the fourth pushing part and the third pushing part. During implantation, the second pushing part outwards pushes the sleeve to be attached to the wall of the medullary cavity, the internal pushing structure acts successively under the counter-acting force, and finally the first pushing part is separated from the second pushing part. Then bone cement is injected through a sleeve micropore, and the stability of the prosthesis is enhanced. By means of the design, intraoperative adaptation and stable filling are achieved.

The utility model provides a biological tibia prosthesis and a biological knee joint prosthesis. The biological type tibia prosthesis comprises a tibia support, a tibia prosthesis middle column is arranged on the bottom face of the tibia support, a rotatable ratchet wheel is arranged on the tibia prosthesis middle column, at least part of the ratchet wheel protrudes out of the outer surface of the tibia prosthesis middle column, a stop assembly is further arranged in the tibia prosthesis middle column, and the stop assembly can limit one-way rotation of the ratchet wheel. When the tibia prosthesis center pillar moves towards the inside of the medullary cavity, the ratchet wheel rotates under the action of the wall of the medullary cavity, and when the tibia prosthesis center pillar moves towards the outside of the medullary cavity, the ratchet wheel is kept in a static state under the action of the locking assembly. The biological knee joint prosthesis comprises the biological tibia prosthesis. According to the biological type tibia prosthesis, when the middle column of the tibia prosthesis moves towards the inside of a medullary cavity, the ratchet wheel can still be embedded into bone cortex and has a fixing function, and when the middle column of the tibia prosthesis moves towards the outside of the medullary cavity, the ratchet wheel is kept in a static state under the action of the stop assembly and has an anti-pulling effect.

A repair device for a proximal humeral fracture includes a stable structure, and the stable structure is connected to a humerus through a humeral medullary cavity supporting portion, a first insertion body, a fitting portion, and a second insertion body. The first insertion body is coupled to the second insertion body, the first insertion body is connected to a humeral head, and the second insertion body is clamped on the fitting portion. After the repair device is implanted into a body of a patient, a fractured site of the patient almost can take full-range early activities upon a surgery. A threaded end of the first insertion body is fixedly connected to the humeral head to realize fixed connection between the repair device and the humeral head. The second insertion body is connected to the first insertion body in an adjustable manner.

The invention provides a multi-column integrated biological fixation partial femoral head replacement device, and relates to the field of medical instruments. The device comprises a bone nail, an auxiliary fixing piece and a joint prosthesis, the bone nail is provided with a first end part and a second end part nailed into a femoral neck medullary cavity, and the first end part, the auxiliary fixing piece and the joint prosthesis are integrally formed; the auxiliary fixture has a first surface and a second surface in contact with the conical osteotomy femoral head to prevent sinking and lateral rotation. The joint prosthesis only replaces the cut part of the necrotic femoral head, more normal sclerotin can be reserved, trauma is small, femoral head supporting and bearing are not affected or changed, long-term stability of the joint prosthesis is guaranteed, and meanwhile future rebuilding is facilitated. In addition, the first end part, the auxiliary fixing piece and the joint prosthesis are integrally formed, so that joint prosthesis failure caused by looseness or corrosion among the first end part, the auxiliary fixing piece and the joint prosthesis can be avoided.

The application discloses a mechanical locking type tibial platform, a tibial prosthesis and a knee joint prosthesis. The mechanical locking type tibial platform comprises a platform holder used for being attached to the proximal end of a tibia, a middle column extending downward along the center of the platform holder and used for being inserted into the marrow cavity of the tibia, an axial hole being arranged in the center of the middle column, a sleeve arranged in the axial hole of the middle column, a limiting structure being arranged on the outer wall of the sleeve, the limiting structure being configured to cooperate with the middle column to enable the sleeve to slide only in the axial direction of the axial hole, a fastener connected to the sleeve and protruding from the outer side wall of the middle column and used for being inserted into the cortical bone of the tibia, and a stand column, one end of the stand column being provided with a limiting block used for abutting against the top surface of the platform holder, and the other end of the stand column being provided with a threaded segment which is threadedly connected to the inner wall of the sleeve. The cooperation of the stand column, the sleeve and the fastener can lock the platform holder to the proximal end of the tibia and ensure the initial stability of the tibial platform.

The invention discloses a bionic type tibia intramedullary nail and a matched instrument thereof, and relates to the technical field of medical instruments, and the bionic type tibia intramedullary nail comprises an intramedullary nail body; the intramedullary nail body comprises an intramedullary nail near end, an intramedullary nail middle section and an intramedullary nail far end, the intramedullary nail middle section is inserted into the intramedullary nail near end in a threaded mode, and the intramedullary nail far end is inserted into the intramedullary nail middle section in a threaded mode; according to the intramedullary nail, through the sectional type thread inserting design of the intramedullary nail near end, the intramedullary nail middle section and the intramedullary nail far end and the matching of the variable pitch gradient structures of the near end thread, the middle section thread and the far end thread, precise adaptation of the intramedullary nail and the anatomical form of the tibia marrow cavity is achieved, and a gradient mechanical buffering system is formed by the near end thread, the middle section thread and the far end thread; the problem of stress shielding caused by the fact that rigidity of a traditional intramedullary nail is not matched with a skeleton is effectively solved, meanwhile, the variable-pitch threads and the thread depth gradual change design are adopted, damage to an endosteum during nail placement is reduced, uniform stress conduction is achieved, local stress concentration is avoided, and the risks of osteoporosis, delayed fracture healing and secondary fracture are reduced.

Systems that may be used for performing a robotic revision knee arthroplasty are disclosed. Such systems can optionally include a processor that can: intraoperatively receive a plurality of position data obtained by a robotic surgical device after a primary implant has been removed from a bone, the plurality of position data correspond to a plurality of landmarks of the bone of a patient, the plurality of landmarks include a position of an intramedullary canal of the bone; select from a database having a plurality of mean models of a corresponding bone a mean model that comprises a best match based upon the plurality of landmarks of the bone: generate an updated model by altering the mean model to fit an anatomy of the bone of the patient based upon the plurality of landmarks; and output to a user interface the updated model for use during the robotic revision knee arthroplasty.

The utility model provides a femoral stem, and relates to the field of passive medical instruments. Comprising a femoral stem conical part, a femoral stem neck part, a femoral stem shoulder part and a stem body, one end of the femoral stem neck part is connected with the stem body through the femoral stem shoulder part, and the other end of the femoral stem neck part is connected with the femoral stem conical part; at least two first protrusions are evenly arranged on the handle body and around the circumference of the handle body, the length of the first protrusions is equal to that of the handle body, and a second protrusion is arranged between every two adjacent first protrusions. The femoral stem can adapt to marrow cavities of different shapes and sizes, and can better adapt to anatomical features of cortical bones and thighbones of the marrow cavities of patients.

The application provides a controllable self-expanding intramedullary nail internal fixation system for long bone fracture, belonging to the technical field of orthopedic medical instruments, and comprising a self-expanding intramedullary nail, a visible controllable self-expanding platform and a locking nail; the self-expanding intramedullary nail comprises a locking hole and an expandable support; the locking hole is arranged at the proximal end of the self-expanding intramedullary nail and is matched with the locking nail to fix the proximal end of the self-expanding intramedullary nail; the expandable support is arranged at the distal end of the self-expanding intramedullary nail after expansion to fix the distal end of the self-expanding intramedullary nail. The visible controllable self-expanding platform is in communication with the expandable support and can display the expansion size, and the self-expanding intramedullary nail can be prevented from being expanded too large to affect the medullary cavity by precalculating the expansion size.

The application provides a femoral stem prosthesis and a hip joint prosthesis with the same, wherein the femoral stem prosthesis comprises: a mounting block comprising a first block body and a second block body, the second block body being arranged on the side of the first block body, and the first block body and the second block body being capable of relative movement; a guide structure arranged between the first block body and the second block body, the guide structure extending along the axial direction of the first block body; a locking assembly arranged between the first block body and the second block body to fix the first block body and the second block body; a support column swingably arranged on the second block body, and an acetabular component arranged on the support column; and a fixing mechanism arranged below the first block body and capable of being inserted into the medullary cavity. The technical scheme of the application effectively solves the problem that the relative position of the neck stem of the femoral stem and the stem body cannot be adjusted in the related art.

Bone harvesting system including methods and devices for obtaining and / or removing osseous debris from a bone using an auger having a flexible, helical fin projecting from a shaft. In an exemplary method, a leading end region of the auger is placed into a reamed portion of a bone's medullary cavity via an entry site extending into the bone. Osseous debris is driven toward the entry site with the auger. At least a portion of the osseous debris that has passed through the entry site is collected outside the bone. In some embodiments, the leading end region of the auger is deformed by contact between the helical fin and a wall of the medullary cavity, to conform the helical fin in the leading end region to a portion of the medullary cavity.

The invention relates to the field of medical instruments, and provides a conicity-locked osseointegration prosthesis. The osseointegration prosthesis comprises an implantation prosthesis, a percutaneous device and an abutment screw, a plurality of fixing ridges are arranged on the periphery of the implantation prosthesis, intraosseous fixation is achieved in a press-fit mode, a taper locking structure is combined to prevent the implantation prosthesis from sinking, and it is ensured that the position of the implantation prosthesis is fixed after implantation; a flushing hole communicated with the internal flushing cavity is further formed in the periphery of the implant prosthesis, and the implant prosthesis can be used for injecting medicine into the medullary cavity, implanting bone materials and the like or used for follow-up flushing treatment for intramedullary infection possibly occurring in the later period. The percutaneous device and the implanted prosthesis are connected through the anti-rotation structure and the taper locking structure, the percutaneous section has the surface state formed through surface treatment, stimulation to surrounding soft tissue is reduced, the anti-infection capacity is improved, and the percutaneous sealing effect is improved. By optimizing the implantation structure and the percutaneous interface design, the intraoperative operation difficulty is reduced, the intraoperative time is shortened, meanwhile, the percutaneous stoma is reduced, and the infection risk is reduced.

A system and method for determining the position of a broach tool used in total hip arthroplasty are disclosed herein, where the broach is still positioned within the femoral canal of the patient's femur, and the position is determined after the broach. Also disclosed herein is an example of a broach tool adapter used to attach a tracking array to the broach tool, the adapter having a body shape that mates with the geometric shape of a particular brand of broach tool and having a common slot defined therein for receiving a tracking array such as attaching the tracking array to the broach tool.

The application discloses a guiding locking device and a fracture fixation system thereof, and relates to the technical field of medical devices. The guiding locking device comprises a guiding locking pipe and a locking piece, at least one strip-shaped slot is arranged on the pipe wall of the guiding locking pipe and communicates with the pipe cavity of the guiding locking pipe, the strip-shaped slot penetrates through the locking end, and the locking piece can drive the pipe wall of the locking end to contract. The fracture fixation system comprises a bone plate, a bone needle and the guiding locking device, a fixing through hole is arranged on the bone plate, the connecting end of the guiding locking pipe is fixedly connected with the fixing through hole, the guiding locking pipe is arranged perpendicularly to the bone plate, the bone needle is arranged in the pipe cavity of the guiding locking pipe, and the locking piece can drive the pipe wall of the locking end to contract and clamp the bone needle. The application reduces the risk of fracture displacement when the bone needle is used to fix the fracture; avoids the influence of the bone needle on the placement of the bone plate; shortens the length of the bone needle entering the medullary cavity, so that the application scene of the temporary fracture fixation technology of the bone needle is not limited in the treatment of the fracture by the intramedullary nail; and the stability is better than that of the multiple bone needles used to fix the fracture.

The utility model discloses a far-end precise locking intramedullary nail system which comprises an intramedullary nail, an intramedullary nail locking device, an intramedullary nail locking device, an intramedullary nail locking device and an intramedullary nail locking device. The far-end hole is formed in the intramedullary nail; the far-end hole is matched with the lock nail, and the bone substance is provided with a screw-in hole upper part and a screw-in hole lower part through which the lock nail penetrates; the thickened part is arranged at the end, away from the intramedullary nail, of the lock nail, external threads are arranged on the peripheral face of the lock nail, and internal threads matched with the external threads are arranged in the lower portion of the far-end hole and the lower portion of the screwing-in hole. The inner diameter of the upper portion of the bone screwing-in hole is slightly larger than the outer diameter of the lock nail, the outer diameter of the thickened portion is gradually increased in the direction away from the intramedullary nail, when the lock nail is screwed in, the lock nail completely penetrates through the upper portion of the screwing-in hole and the far-end hole and partially extends into the lower portion of the screwing-in hole, and the thickened portion of the lock nail is embedded into the upper portion of the screwing-in hole. At the moment, the intramedullary nail can be fixed to the bone through the lock nail, displacement is avoided, and precise locking of the intramedullary nail is achieved.

The application relates to a medical orthopedic quick drill bit, which comprises a drill bit body composed of a drill bit part and a drill rod part, wherein the drill bit part is provided with circularly arranged cutting edges for bone positioning and hole forming, and the drill rod part is designed as a light rod; a connecting piece is connected with the drill bit body at one end and fixed with a driving piece at the other end, and the two are quickly separated through a split device containing a clamping piece and a disengaging piece, so that safe disconnection is ensured when the pressure of the medullary cavity or cancellous bone is abnormal. The application has the technical effects of improving the operation efficiency, enhancing the safety and reducing accidental injuries.

The utility model relates to the field of medullary cavity files, in particular to a medullary cavity file for replacement surgery, which comprises a file handle body, a medullary cavity file body is inserted on the file handle body, a fixing piece is fixedly mounted on the medullary cavity file body, and the fixing piece and the file handle body are limited through a limiting insertion rod assembly. A limiting inserting groove is formed in the position, located on the limiting inserting rod assembly, in the file handle body, an auxiliary assembly is arranged on the position, located on one side of the limiting inserting groove, in the file handle body, and the file handle body and the limiting inserting rod assembly are limited through the auxiliary assembly. According to the medullary cavity file, the auxiliary assembly, the limiting cover cap and the limiting insertion rod assembly are arranged in a matched mode, the file handle body and the medullary cavity file body can be rapidly disassembled and assembled, the normal operation process is convenient and fast, the disassembling and assembling time is greatly shortened, and meanwhile disassembling and assembling operation can be conducted without other extra tools.

The utility model discloses a metal 3D printing porous bone induction structure tibial prosthesis, which comprises a diaphysis prosthesis, a bone fracture plate and an intramedullary nail, the diaphysis prosthesis is designed according to the anatomical form of the focus part of a patient, the diaphysis prosthesis comprises a solid framework and a porous structure, and a cavity is arranged in the diaphysis prosthesis; the at least two bone fracture plates are connected to the two ends of the diaphysis prosthesis in the tibia direction respectively, and the at least two bone fracture plates are connected with the tibia near end and the tibia far end through screws respectively. The tibia near end comprises a first medullary cavity, the tibia far end comprises a second medullary cavity, the intramedullary nail penetrates through the first medullary cavity, the cavity and the second medullary cavity, and the two ends of the intramedullary nail are connected with the tibia near end and the tibia far end through screws respectively. The utility model can solve the problems of incapability of realizing rapid healing, poor initial stability and poor long-term stability in the existing bone defect reconstruction.

An intramedullary implant (1) for connection to a prosthetic device (E), comprising a main stem (2) having a proximal end (3) for insertion into a medullary cavity of a bone stump (B) and a distal end (4) for engagement with the prosthetic device (E). The main stem (2) comprises a medullar section (5) extending from the proximal end (3) in distal direction (D), and a coupling section (6) extending from the distal end (4) in proximal direction (P). The medullar section (5) and coupling section (6) meet at an insertion point (S) along the main stem (2) between the proximal end (3) and the distal end (4), wherein the insertion point (S) designates a maximum insertion depth (Di) into the medullar cavity. The coupling section (6) has a constant coupling diameter (d1) extending from the insertion point (S) to the distal end (4).