Femoral stem prosthesis for severe hip dysplasia

Abstract

The application provides a femoral stem prosthesis for severe hip dysplasia, which comprises a first section and a second section which are integrally formed and distributed along the up-down direction, the first section is used for penetrating and press-fitting in the proximal segment of the femur, and the second section is used for inserting and press-fitting in the distal segment of the femur. The first section and the second section adopt a tapered structure, which can improve the axial stability, and the rotation-stopping structure outside the first section and the second section can limit the relative rotation of the prosthesis and the femur. The second section of the femoral stem prosthesis can select a suitable size according to the actual situation of the femur of the patient, so as to improve the stability of the connection, when the second section is stably connected with the distal segment of the femur, the proximal segment of the femur is press-fitted with the first section, and finally the femoral stem prosthesis is continuously pressed, so that the cross section of the distal segment of the femur and the proximal segment of the femur is in contact and sufficient pressing force is provided.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a femoral stem prosthesis for severe hip dysplasia. Background Technology

[0002] Total hip arthroplasty is an effective treatment for end-stage hip joint disease. However, for patients with severe hip dysplasia type IV, the significant anatomical deformities on the femoral side pose a great challenge to artificial hip arthroplasty. These patients have a thin femoral medullary canal, a severe mismatch between the diameters of the proximal metaphysis and the distal diaphysis, significant limb shortening, and an abnormally increased femoral anteversion angle.

[0003] To address the aforementioned challenges, specialized modular prostheses, such as the S-ROM type, are widely used in clinical practice for reconstruction. The core structure of the S-ROM prosthesis consists of a proximal sleeve and a distal stem. The proximal sleeve features a porous, coated design and is implanted into the shaved proximal femoral metaphysis medullary canal via press-fitting, aiming for long-term biological fixation through bone ingrowth. The distal stem is integrated with the femoral neck and is typically an uncoated, polished design with a tuning fork-like bifurcation at its distal end. During surgery, the sleeve is first implanted, and then the distal stem is passed through the central channel of the sleeve and press-fitted into the narrow distal femoral medullary canal. The rotational stability of this prosthesis primarily relies on the press-fitting of the distal bifurcation structure with the femoral canal, while axial stability is maintained by the overall press-fitting of the prosthesis and the support of the femoral osteotomy end.

[0004] In the aforementioned prosthesis implantation process, to overcome soft tissue contracture and reposition the artificial joint to its true acetabular position, most patients require simultaneous subtrochanteric shortening osteotomy of the femur. The ideal goal of postoperative rehabilitation is to achieve reliable osseointegration of the proximal sleeve while ensuring bony healing at the osteotomy site, thereby establishing long-term stability of the prosthesis.

[0005] Although the aforementioned modular prostheses have addressed the femoral medullary canal mismatch to some extent, their medium- to long-term clinical outcomes in patients with high hip dislocation remain unsatisfactory, with a significantly higher failure rate than conventional hip replacement. Existing technologies primarily suffer from the following inherent limitations: First, the central channel diameter of the proximal sleeve is fixed, which severely limits the maximum diameter of the distal stem that can pass through. For patients with extremely narrow medullary canals and high dislocations, surgeons are often forced to use a smaller diameter distal stem. This thin stem makes it difficult to achieve effective compression fitting within the relatively large distal bone canal, resulting in poor rotational stability of the distal prosthesis. Under repeated postoperative physiological loads, the distal prosthesis experiences micromovements, and stress cannot be effectively transmitted to the osteotomy end, leading to delayed healing or even nonunion at the osteotomy end, ultimately causing overall prosthesis loosening. This is one of the most significant complications of the current surgical procedure.

[0006] Secondly, to compensate for the lack of stability caused by the thin stem to some extent, existing technologies have designed a tuning fork-like bifurcated structure. However, this structure creates a stress concentration area on the stem. Simultaneously, the excessively thin stem diameter used to accommodate the narrow medullary cavity also reduces the fatigue strength of the prosthesis material. Under long-term, cyclic loading, the prosthesis is prone to fatigue fracture at the junction of the distal stem and the tuning fork structure, or at the stem itself, leading to surgical failure.

[0007] Third, when patients require a thicker distal stem for better distal stability, surgeons are forced to use a proximal cuff with a larger inner diameter. To implant this larger cuff, the already underdeveloped proximal femoral metaphysis with insufficient bone reserve must be excessively ground down. This further weakens the already thin proximal bone, significantly increasing the risk of intraoperative or postoperative proximal femoral split fractures, and also impairs the initial compression stability of the cuff and its long-term biological environment for bone ingrowth.

[0008] Fourth, the long-term biological fixation of existing prostheses relies entirely on reliable osseointegration between the proximal sleeve and the host bone. Once proximal fixation fails, for example, due to poor bone ingrowth quality or proximal fracture causing the sleeve to loosen, the distal stem itself is designed to be smooth and does not match well with the bone shaft medullary cavity, so it cannot independently provide effective long-term stability. The entire prosthesis system will then fail, making salvage stability difficult to achieve.

[0009] Besides the modular prostheses mentioned above, Wagner Cone-type conical stems are also used clinically to adjust abnormal anteversion angles of the prosthesis. However, when high prolapse patients require simultaneous subtrochanteric osteotomy of the femur, this type of prosthesis also has inherent drawbacks: First, after distal fixation, the proximal end cannot control the rotational stability of the proximal femoral osteotomy block due to insufficient proximal prosthesis thickness, resulting in the proximal bone block failing to integrate with the prosthesis and failing to achieve bony healing with the distal bone block. Second, due to insufficient proximal diameter of the prosthesis, it is impossible to apply downward pressure by inserting it during the operation, resulting in micromovement between the proximal and distal osteotomy surfaces, which affects osteotomy healing. Summary of the Invention

[0010] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a femoral stem prosthesis for severe hip dysplasia, aiming to solve the problem that existing prostheses cannot simultaneously achieve good matching and stable fixation of the proximal and distal medullary canals when performing subtrochanteric osteotomy in patients with Crowe type IV hip dysplasia, resulting in insufficient rotational stability, poor healing of the osteotomy ends, and long-term loosening and failure of the prosthesis.

[0011] This invention provides a femoral stem prosthesis for severe hip dysplasia, comprising a first segment and a second segment, wherein the first segment is located at the top of the second segment, and the two are integrally formed, wherein: The first segment is used to penetrate the proximal femur, and its outer surface is pressed against the medullary canal wall of the proximal femur. The outer surface of the first segment is a tapered structure with an outer diameter that gradually increases from bottom to top. The portion of the second segment furthest from the first segment is used for insertion and pressing into the medullary cavity of the distal femur. The outer surface of the second segment is cylindrical or a conical structure with an outer diameter that gradually increases from bottom to top. The outer diameter of the top end of the second segment is equal to the outer diameter of the bottom end of the first segment. When the outer surface of the second segment is a conical structure, the taper of the second segment is smaller than that of the first segment. Both the first segment and the second segment have anti-rotation structures on their outer surfaces for engaging with the inner wall of the medullary cavity.

[0012] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the anti-rotation structure includes at least one anti-rotation ridge disposed on the outer surface of the first segment and the second segment, the anti-rotation ridge extending along the generatrix of the outer surface of the first segment or the second segment, and when there are multiple anti-rotation ridges, the multiple anti-rotation ridges are circumferentially distributed along the outer surface of the first segment or the second segment.

[0013] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the number of antirotation ridges on the first segment and the second segment is the same, and the plurality of antirotation ridges on the first segment are arranged in a one-to-one correspondence with the plurality of antirotation ridges on the second segment.

[0014] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the antirotation ridge is a strip-shaped protrusion extending outward from the lateral surface of the first segment or the second segment.

[0015] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the outer surfaces of the first segment and the second segment are each provided with a strip-shaped groove extending inward from their outer surfaces, and the portion located between two adjacent strip-shaped grooves forms the anti-rotation ridge.

[0016] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the outer diameter of the top end of the first segment is 14 mm, 18 mm or 20 mm, and the outer diameter of the bottom end of the first segment is greater than or equal to 9 mm and less than 20 mm.

[0017] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the outer diameter of the top end of the second segment is greater than or equal to 9 mm and less than or equal to 14 mm, the outer peripheral surface of the second segment is cylindrical, and the outer diameter of the bottom end of the second segment is any value between 9 mm and 14 mm.

[0018] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, the outer diameter of the top end of the second segment is greater than 14 mm and less than 20 mm, the outer peripheral surface of the second segment is a tapered structure that gradually increases from bottom to top, and the outer diameter of the bottom end of the second segment is any value between 9 mm and 14 mm.

[0019] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, at least the outer surface of the first segment is provided with a sandblasted coating.

[0020] According to the femoral stem prosthesis for severe hip dysplasia provided by the present invention, at least the outer surface of the first segment is a porous structure.

[0021] The present invention has the following advantages due to the adoption of the above technical solutions: The femoral stem prosthesis for severe hip dysplasia provided by this invention involves first grinding the medullary canals of the proximal and distal femurs during installation. Then, the proximal femur is inserted from the bottom of the second segment to the first segment, and the first segment is pressed against the proximal femur. Next, the second segment is inserted from the proximal end of the distal femur until the cross-sections of the proximal and distal femurs are in full contact, indicating proper installation. This invention creatively integrates the first and second segments, which have different diameters, into one unit. The diameters of the first and second segments can be independently optimized according to each patient's femoral morphology, solving the core problem of medullary canal mismatch in patients with high hip dysplasia. The proximal and distal segments can be selected independently, avoiding excessive grinding of the proximal bone to match the distal segment, significantly reducing the risk of intraoperative proximal femoral fracture, and preserving valuable bone volume for long-term fixation. This femoral stem prosthesis lacks a sleeve, and the diameter of the second segment is not constrained by the inner diameter of the sleeve. A sufficiently thick stem can be selected based on the patient's actual medullary cavity, ensuring strong fixation initially in the bone shaft region with the best bone quality. This lays a stable foundation for subsequent proximal fixation and osteotomy compression, achieving optimal compression fit and rotational locking with the femoral shaft. This significantly reduces the risk of prosthesis loosening and osteotomy nonunion caused by distal micromovement. Furthermore, it eliminates weak designs such as assembly interfaces and tuning forks, employing a one-piece forging process to completely eliminate the risk of prosthesis fatigue fracture and improve long-term durability. Moreover, it achieves simultaneous biological fixation of the femoral stem prosthesis to both the distal and proximal femurs, resulting in a more stable connection. This femoral stem prosthesis allows for controlled axial compression of the osteotomy surface at the final stage, creating an ideal mechanical environment for osteotomy healing and potentially reducing the osteotomy nonunion rate to the level of conventional joint replacement. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a femoral stem prosthesis for severe hip dysplasia provided in an embodiment of the present invention; Figure 2 This is a rear view of a femoral stem prosthesis for severe hip dysplasia provided in an embodiment of the present invention; Figure 3 This is provided by an embodiment of the present invention. Figure 2 AA view; Figure 4This is a side view of a femoral stem prosthesis for severe hip dysplasia provided in an embodiment of the present invention; Figure 5 This is provided by an embodiment of the present invention. Figure 4 BB view; Figure 6 This is provided by an embodiment of the present invention. Figure 4 CC view; Figure 7 This is provided by an embodiment of the present invention. Figure 4 DD view.

[0024] Figure label: 100: First segment; 200: Second segment; 300: Anti-rotation ridge. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0031] The femoral stem prosthesis for severe hip dysplasia provided by this invention involves first grinding the medullary canals of the proximal and distal femurs during installation. Then, the proximal femur is inserted from the bottom of the second segment to the first segment, and the first segment is pressed against the proximal femur. Next, the second segment is inserted from the proximal end of the distal femur until the cross-sections of the proximal and distal femurs are in full contact, indicating proper installation. This invention creatively integrates the first and second segments, which have different diameters, into one unit. The diameters of the first and second segments can be independently optimized according to each patient's femoral morphology, solving the core problem of medullary canal mismatch in patients with high hip dysplasia. The proximal and distal segments can be selected independently, avoiding excessive grinding of the proximal bone to match the distal segment, significantly reducing the risk of intraoperative proximal femoral fracture, and preserving valuable bone volume for long-term fixation. This femoral stem prosthesis lacks a sleeve, and the diameter of the second segment is not constrained by the inner diameter of the sleeve. A sufficiently thick stem can be selected based on the patient's actual medullary cavity, ensuring strong fixation initially in the bone shaft region with the best bone quality. This lays a stable foundation for subsequent proximal fixation and osteotomy compression, achieving optimal compression fit and rotational locking with the femoral shaft. This significantly reduces the risk of prosthesis loosening and osteotomy nonunion caused by distal micromovement. Furthermore, it eliminates weak designs such as assembly interfaces and tuning forks, employing a one-piece forging process to completely eliminate the risk of prosthesis fatigue fracture and improve long-term durability. Moreover, it achieves simultaneous biological fixation of the femoral stem prosthesis to both the distal and proximal femurs, resulting in a more stable connection. This femoral stem prosthesis allows for controlled axial compression of the osteotomy surface at the final stage, creating an ideal mechanical environment for osteotomy healing and potentially reducing the osteotomy nonunion rate to the level of conventional joint replacement.

[0032] The following is combined Figures 1 to 7 The present invention describes a femoral stem prosthesis for severe hip dysplasia.

[0033] An embodiment of the present invention provides a femoral stem prosthesis for severe hip dysplasia, comprising a first segment 100 and a second segment 200, wherein the first segment 100 is located on top of the second segment 200, and the two are integrally formed.

[0034] During the surgery, the femur needs to be shortened, resulting in two segments: a proximal femur closer to the hip bone and a distal femur closer to the knee joint.

[0035] The first segment 100 is used to penetrate the proximal femur, and its outer surface is pressed against the inner wall of the medullary cavity of the proximal femur. The outer surface of the first segment 100 is a conical structure with an outer diameter that gradually increases from bottom to top.

[0036] The portion of the second segment 200 furthest from the first segment 100, i.e., the distal end of the second segment 200, is used for insertion and compression fitting into the medullary canal of the distal femur. The lateral surface of the second segment 200 is either cylindrical or a tapered structure with its outer diameter gradually increasing from bottom to top. The outer diameter of the apex of the second segment 200 is equal to the outer diameter of the bottom of the first segment 100, and the two transition smoothly at the interface. When the lateral surface of the second segment 200 is tapered, the taper of the second segment 200 is much smaller than that of the first segment 100.

[0037] In addition, anti-rotation structures for engaging with the inner wall of the medullary cavity are provided on the outer surfaces of the first segment 100 and the second segment 200.

[0038] During installation, the medullary canals of the proximal and distal femurs are first processed. Then, the proximal femur is inserted through the bottom of the second segment 200 of the femoral stem prosthesis to the lateral side of the first segment 100. Next, the bottom of the second segment 200 is inserted through the top of the distal femur until the second segment 200 is stably supported within the distal femur. The proximal end of the medullary canal of the proximal femur is then further processed, and the proximal femur is press-fitted and fixed to the first segment 100. Finally, downward pressure is applied to the femoral stem prosthesis to press-fit the cross-sections of the proximal and distal femurs together.

[0039] The tapered design facilitates a tight fit with the narrow femoral medullary canal, providing axial stability. The anti-rotation structure restricts the relative rotation between the femoral stem prosthesis and the femur. The first segment 100 is an enlarged tapered structure with a greater taper than the second segment 200. This is suitable for the rapidly narrowing metaphyseal medullary canal in dysplastic patients, and is beneficial for proximal filling and fixation.

[0040] This invention provides a femoral stem prosthesis for severe hip dysplasia, creatively integrating a first segment (100° tapered expansion) with a second segment (200° thin stem) of varying diameters. Previously, femoral stems, whether one-piece tapered or modular, exhibited continuous or limited diameter variations at the proximal and distal ends, either due to the size of the sleeve. This invention, for the first time, allows for independent diameter optimization of the proximal and distal segments on a single prosthesis based on anatomical requirements. This is crucial for resolving the core challenge of mismatch between the proximal and distal medullary canals in patients with hip dysplasia.

[0041] This femoral stem prosthesis employs a surgical procedure that first fixes the distal end, then the proximal end, overturning the traditional implantation logic of modular prostheses. This ensures that the femoral stem prosthesis can first achieve strong fixation in the bone shaft region with the best bone quality, laying a stable foundation for subsequent proximal fixation and osteotomy compression.

[0042] This femoral stem prosthesis achieves bipolar biological fixation of both proximal and distal segments. Specifically, the lateral wall of the first segment 100 presses against the proximal femur to achieve proximal osseointegration, while the second segment 200 presses against the distal femoral medullary cavity to achieve close interlocking with the cortical bone, completing osseointegration. This represents a fundamental advancement compared to existing modular stems that rely solely on proximal fixation, and traditional one-piece conical stems that cannot simultaneously satisfy osteotomy fixation and bipolar biological fixation.

[0043] This femoral stem prosthesis fundamentally solves the problem of distal loosening. The diameter of the second segment 200 is no longer limited by the size of the proximal sleeve channel. A sufficiently thick stem can be selected according to the patient's actual medullary cavity to achieve optimal compression fit and rotational locking with the femoral shaft, greatly reducing the risk of prosthesis loosening and osteotomy nonunion caused by distal micromovement.

[0044] The femoral stem prosthesis, with its distal-to-proximal implantation approach, allows for controlled axial compression of the osteotomy surface at the final stage, creating an ideal mechanical environment for osteotomy healing and potentially reducing the rate of osteotomy nonunion to that of conventional joint replacement.

[0045] This femoral stem prosthesis eliminates weak designs such as assembly interfaces and tuning forks, and is made in one piece by forging, which completely eliminates the risk of fatigue fracture of the prosthesis and improves the long-term durability of the prosthesis.

[0046] This femoral stem prosthesis maximizes bone preservation, with the first segment 100 and the second segment 200 models being independently selectable. This avoids excessive grinding of the proximal bone to match the outer diameter of the second segment 200, significantly reducing the risk of intraoperative proximal femoral fractures and preserving valuable bone volume for long-term fixation.

[0047] This femoral stem prosthesis can precisely match the outer diameter of the first segment 100 and the second segment 200, thus enabling more accurate matching of the diverse femoral medullary cavity anatomy of Crow IV type patients of various body types, achieving truly individualized reconstruction.

[0048] In some embodiments, the anti-rotation structure described above may include at least one anti-rotation ridge 300 disposed on the outer surface of the first segment 100 and the second segment 200. The anti-rotation ridge 300 extends along the generatrix of the first segment 100 or the outer surface of the first segment 100. When the number of anti-rotation ridges 300 is greater than or equal to two, the plurality of anti-rotation ridges 300 are circumferentially distributed along the outer surface of the first segment 100 or the second segment 200.

[0049] For example, six anti-rotation ridges 300 are provided on both the first segment 100 and the second segment 200. After the first segment 100 is inserted into the proximal femur or the second segment 200 is inserted into the distal femur, the anti-rotation ridges 300 are inserted into the wall of the medullary cavity to restrict the relative rotation between the femur and the femoral stem prosthesis.

[0050] In a preferred embodiment, the number of anti-rotation ridges 300 on the first segment 100 is the same as the number of anti-rotation ridges 300 on the second segment 200, and the plurality of anti-rotation ridges 300 on the first segment 100 and the plurality of anti-rotation ridges 300 on the second segment 200 are arranged in a one-to-one correspondence.

[0051] Thus, as the second segment 200 passes through the proximal femur, a groove is formed in the medullary canal of the proximal femur that engages with the antirotation ridge 300 located on the second segment 200. As the first segment 100 enters the proximal femur, the antirotation ridge 300 located on the outside of the first segment 100 will enter the groove that has already been formed.

[0052] If the anti-rotation ridge 300 on the first segment 100 is not aligned with the anti-rotation ridge 300 on the second segment 200, a corresponding first groove will be formed when the second segment 200 passes through the proximal femur. When the first segment 100 passes through the proximal femur again, a second groove corresponding to the anti-rotation ridge 300 of the first segment 100 will be formed.

[0053] When the anti-rotation ridge 300 on the first segment 100 and the anti-rotation ridge 300 on the second segment 200 partially overlap along the extension direction, the first groove and the second groove formed in the proximal femur will connect to form a groove. Moreover, the width of this groove is greater than the width of the anti-rotation ridge 300 of the first segment 100, and it will lose the effect of restricting relative rotation.

[0054] When the anti-rotation ridge 300 on the first segment 100 and the anti-rotation ridge 300 on the second segment 200 are completely misaligned along the extension direction, the thickness of the medullary canal wall of the proximal femur located between the first groove and the second groove will become thinner, and it will also lose its effect of restricting relative rotation.

[0055] Specifically, the anti-rotation ridge 300 can be a strip-shaped protrusion extending outward from the outer side of the first segment 100 or the second segment 200, with the protrusion forming the anti-rotation ridge 300.

[0056] Alternatively, a strip-shaped groove extending inward from its outer side is provided on the outer surface of the first segment 100 and the second segment 200, and the portion located between adjacent strip-shaped grooves forms the aforementioned anti-rotation ridge 300.

[0057] In some embodiments, the outer diameter of the top end of the first segment 100 can be 14 mm, 18 mm or 20 mm, and the outer diameter of the bottom end of the first segment 100 is greater than or equal to 9 mm and less than 20 mm. The appropriate model of the first segment 100 can be selected according to the actual condition of the patient's femur.

[0058] The top outer diameter of the second segment 200 is less than or equal to 14 mm. Since the bottom outer diameter of the first segment 100 is equal to the top outer diameter of the second segment 200, the top outer diameter of the second segment 200 is greater than or equal to 9 mm. Within this size range, the outer circumferential surface of the second segment can be cylindrical, and the bottom outer diameter of the second segment 200 can be any value between 9 mm and 14 mm.

[0059] In one specific embodiment, the bottom outer diameter of the second segment 200 can increase in increments of 1 mm, that is, the bottom outer diameter of the second segment 200 can be 9 mm, 10 mm, 11 mm, 12 mm, 13 mm or 14 mm.

[0060] In another embodiment, the outer diameter of the top end of the second segment 200 is greater than 14 mm and less than 20 mm. In this case, the outer peripheral surface of the second segment 200 can be a tapered structure that gradually increases from bottom to top, and the outer diameter of the bottom end of the second segment 200 can be any value between 9 mm and 14 mm.

[0061] Similarly, the outer diameter of the bottom end of the second segment 200 can also increase in increments of 1 mm, that is, the outer diameter of the bottom end of the second segment 200 can be 9 mm, 10 mm, 11 mm, 12 mm, 13 mm or 14 mm.

[0062] In practical use, the first segment 100 of each size model can be matched with the second segment 200 of all sizes model to adapt to the actual situation of different patients. The diameter gradient of the bottom subdivision of the second segment 200 and the independent proximal model of the first segment 100 can more accurately match the different femoral medullary cavity anatomy of Crow type IV patients of various body types, achieving truly individualized reconstruction.

[0063] In some embodiments, a sandblasted coating or a porous structure is provided only on the outer surface of the first segment 100, or a sandblasted coating or a porous structure is provided on the outer surfaces of both the first segment 100 and the second segment 200. This can promote osseointegration between the femoral stem prosthesis surface and the medial wall of the femur.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A femoral stem prosthesis for severe hip dysplasia, characterized in that, It includes a first segment (100) and a second segment (200), the first segment (100) being located on top of the second segment (200), and the two being an integrally formed structure, wherein: The first segment (100) is used to penetrate the proximal femur, and its outer surface is pressed against the medullary canal wall of the proximal femur. The outer surface of the first segment (100) is a tapered structure with an outer diameter that gradually increases from bottom to top. The portion of the second segment (200) away from the first segment (100) is used for insertion and pressing into the medullary cavity of the distal femur. The outer surface of the second segment (200) is a cylindrical surface or a conical structure with an outer diameter that gradually increases from bottom to top. The outer diameter of the top end of the second segment (200) is equal to the outer diameter of the bottom end of the first segment (100). When the outer surface of the second segment (200) is a conical structure, the taper of the second segment (200) is less than the taper of the first segment (100). Both the outer surfaces of the first segment (100) and the second segment (200) are provided with anti-rotation structures for engaging with the inner wall of the medullary cavity.

2. The femoral stem prosthesis for severe hip dysplasia according to claim 1, characterized in that, The anti-rotation structure includes at least one anti-rotation ridge (300) disposed on the outer side of the first segment (100) and the second segment (200). The anti-rotation ridge (300) extends along the generatrix of the outer side of the first segment (100) or the second segment (200). When there are multiple anti-rotation ridges (300), the multiple anti-rotation ridges (300) are circumferentially distributed along the outer side of the first segment (100) or the second segment (200).

3. The femoral stem prosthesis for severe hip dysplasia according to claim 2, characterized in that, The number of anti-rotation ridges (300) on the first segment (100) and the second segment (200) is the same, and the plurality of anti-rotation ridges (300) on the first segment (100) and the plurality of anti-rotation ridges (300) on the second segment (200) are arranged in a one-to-one correspondence.

4. The femoral stem prosthesis for severe hip dysplasia according to claim 2 or 3, characterized in that, The anti-rotation ridge (300) is a strip-shaped protrusion extending outward from the outer side of the first segment (100) or the second segment (200).

5. The femoral stem prosthesis for severe hip dysplasia according to claim 2 or 3, characterized in that, The outer surfaces of the first segment (100) and the second segment (200) are provided with strip-shaped grooves extending inward from their outer surfaces, and the portion located between two adjacent strip-shaped grooves forms the anti-rotation ridge (300).

6. The femoral stem prosthesis for severe hip dysplasia according to claim 1, characterized in that, The top outer diameter of the first segment (100) is 14 mm, 18 mm or 20 mm, and the bottom outer diameter of the first segment (100) is greater than or equal to 9 mm and less than 20 mm.

7. The femoral stem prosthesis for severe hip dysplasia according to claim 6, characterized in that, The outer diameter of the top end of the second segment (200) is greater than or equal to 9 mm and less than or equal to 14 mm. The outer circumferential surface of the second segment (200) is cylindrical, and the outer diameter of the bottom end of the second segment (200) is any value between 9 mm and 14 mm.

8. The femoral stem prosthesis for severe hip dysplasia according to claim 6, characterized in that, The outer diameter of the top end of the second segment (200) is greater than 14 mm and less than 20 mm. The outer circumference of the second segment (200) is a tapered structure that gradually increases from bottom to top. The outer diameter of the bottom end of the second segment (200) is any value between 9 mm and 14 mm.

9. The femoral stem prosthesis for severe hip dysplasia according to claim 1, characterized in that, At least the outer surface of the first segment (100) is provided with a sandblasted coating.

10. The femoral stem prosthesis for severe hip dysplasia according to claim 1, characterized in that, At least the outer surface of the first segment (100) is porous.

Images