Surface hip joint replacement prosthesis

Abstract

The invention discloses a surface hip joint replacement prosthesis, and relates to the technical field of medical prostheses, the surface hip joint replacement prosthesis comprises an acetabular cup and a ball head, the ball head is located in the acetabular cup, the ball head and the acetabular cup can rotate relatively, a groove structure and a boss are arranged outside the acetabular cup, an anti-rotation groove is formed in the inner wall of the ball head, and the anti-rotation groove is located in the acetabular cup. A central spindle is arranged in the ball head, and a threaded structure is arranged on the central spindle. The groove structure on the acetabular cup can be embedded with bone cement and is resistant to rotation and disengagement, the boss of the acetabular cup can further improve the bonding strength with the bone cement, and the prosthesis is prevented from retreating; the anti-rotation groove in the ball head is used for being embedded with bone cement and resisting rotation, and the core shaft and the thread structure of the ball head can improve the bonding strength with the bone cement.

Description

Technical Field

[0001] This invention relates to the field of medical prosthesis technology, and in particular to a surface hip joint replacement prosthesis, which is especially suitable for patients with acetabular osteoporosis. Background Technology

[0002] Osteoporosis (T-score ≤ -2.5) leads to a decrease in the elastic modulus of the acetabular cancellous bone and sparse trabeculae, making it impossible for traditional press-fit acetabular cups to achieve sufficient initial stability; early postoperative micromovement can easily cause fibrous membrane ingrowth, eventually leading to aseptic loosening.

[0003] Existing bone cement acetabular cups lack sufficient anti-dislodgement and anti-rotation capabilities, and tend to sink in an "piston-like" manner in osteoporotic bone beds. The existing ball head mandrel fixation methods are limited, mostly using straight-handle press fitting or short-handle bone cement fixation, which lacks sufficient holding force in cancellous bone. Furthermore, the inner surface of the ball head is smooth, resulting in low interfacial shear strength after the bone cement hardens, making it prone to "rotational slippage" under rotational torque. Summary of the Invention

[0004] The purpose of this invention is to provide a surface-mount hip replacement prosthesis to solve the problems existing in the prior art, improve the bonding strength between the acetabular cup and bone cement, and between the acetabular head and bone cement, and prevent rotation and dislocation.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides a surface hip replacement prosthesis, comprising: an acetabular cup and a ball head, wherein the ball head is located in the acetabular cup and is rotatable relative to the acetabular cup; the acetabular cup has a groove structure and a boss on its exterior; the ball head has an anti-rotation groove on its inner wall; and a mandrel is provided inside the ball head, the mandrel having a threaded structure.

[0006] In some specific designs, the groove structure includes several parallel circumferential grooves.

[0007] In some specific embodiments, the groove structure further includes several longitudinal grooves, which are arranged perpendicularly to the circumferential grooves, and the longitudinal grooves and the circumferential grooves are connected at their intersections.

[0008] In some specific embodiments, the surface of the boss is a plane, and the distance between any position on the surface of the boss and the center of the acetabular cup gradually increases from the position on the surface of the boss near the apex of the acetabular cup to the position on the surface of the boss away from the apex of the acetabular cup.

[0009] In some specific embodiments, a plurality of anti-spin grooves are uniformly arranged along the inner wall of the ball head, the size of one end of the anti-spin groove is larger than the size of the other end of the anti-spin groove, and the anti-spin groove extends from one end of the ball head to the other end of the ball head in a direction away from the opening end of the ball head.

[0010] In some specific embodiments, the axis of the mandrel passes through the center of the ball head, one end of the mandrel is connected to the ball head, the other end of the mandrel is located outside the ball head, the mandrel has a taper, and the size of one end of the mandrel is larger than the size of the other end of the mandrel; the thread structure extends along the axis of the mandrel.

[0011] In some specific designs, the diameter of the ball head is larger than the diameter of a standard femoral head; the inner wall of the ball head is tapered, and the inner wall of the ball head contracts from the outside to the inside from the open end of the ball head to the closed end of the ball head.

[0012] In some specific embodiments, the inner surface of the acetabular cup and the outer surface of the ball head are both smooth spherical surfaces; the acetabular cup is a spherical notch smaller than a hemisphere, and the ball head is a spherical crown larger than a hemisphere.

[0013] In some specific designs, the wall thickness of the acetabular cup is less than or equal to 3 mm.

[0014] In some specific designs, the acetabular cup is made of ultra-high molecular weight polyethylene, and the ball head is made of cobalt-chromium-molybdenum alloy.

[0015] The present invention achieves the following technical effects compared to the prior art: The grooved structure on the acetabular cup of this invention allows it to fit with bone cement, preventing rotation and dislodgement. The protrusion on the acetabular cup further enhances the bonding strength with bone cement, preventing prosthesis retraction. The anti-rotation groove inside the ball head is used to fit with bone cement, preventing rotation. The mandrel and threaded structure of the ball head also increase the bonding strength with bone cement. This invention provides an immediately stable and long-term load-bearing bone cement fixation interface for osteoporotic acetabulums. The prosthesis consists of only two components: the acetabular cup and the ball head, simplifying surgical procedures and reducing bone loss. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 Axonometric projection of surface hip replacement prostheses in some embodiments of the present invention Figure 1 ; Figure 2 Axonometric projection of surface hip replacement prostheses in some embodiments of the present invention Figure 2 ; Figure 3 Axiometric view of the acetabular cup in some embodiments of the present invention Figure 1 ; Figure 4 Axiometric view of the acetabular cup in some embodiments of the present invention Figure 2 ; Figure 5 This is a front view of the acetabular cup in some embodiments of the present invention; Figure 6 This is a top view of the acetabular cup in some embodiments of the present invention; Figure 7 This is a top view of the acetabular cup in some embodiments of the present invention; Figure 8 As described in some embodiments of the present invention Figure 7 AA section view; Figure 9 These are isometric views of the ball head in some embodiments of the present invention; Figure 10 This is a front view of the ball head in some embodiments of the present invention; Figure 11 This is a bottom view of the ball head in some embodiments of the present invention; Figure 12 As described in some embodiments of the present invention Figure 11 BB section view; Figure 13 This is a top view of the ball head in some embodiments of the present invention; In the diagram: 100-surface hip replacement prosthesis, 1-acetabular cup, 2-ball head, 3-circumferential groove, 4-longitudinal groove, 5-bore, 6-anti-rotation groove, 7-mandrel, 8-threaded structure. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The purpose of this invention is to provide a surface-mount hip replacement prosthesis to address the problems existing in the prior art, improve the bonding strength between the acetabular cup and bone cement, and between the acetabular head and bone cement, and enhance resistance to rotation and dislocation. To make the above-mentioned objectives, features, and advantages of this invention more apparent and understandable, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figures 1 to 13 As shown, this embodiment provides a surface-mount hip replacement prosthesis 100, suitable for patients with severe osteoporosis and a T-score ≤ -3.0. It includes an acetabular cup 1 and a ball head 2, both fixed with bone cement. The ball head 2 is located within the acetabular cup 1 and can rotate relative to it. The acetabular cup 1 has a groove structure and a boss 5 on its exterior. The ball head 2 has an anti-rotation groove 6 on its inner wall and a mandrel 7 inside, with a threaded structure 8. In this embodiment, the groove structure on the acetabular cup 1 can fit with the bone cement, preventing rotation and dislodgement. The boss 5 of the acetabular cup 1 further enhances the bonding strength with the bone cement, preventing prosthesis retraction. The anti-rotation groove 6 inside the ball head 2 is used for fitting with the bone cement, preventing rotation. The mandrel 7 and threaded structure 8 of the ball head 2 both increase the bonding strength with the bone cement. This embodiment, through the synergistic design of the acetabular cup 1 and the ball head 2, significantly improves the immediate stability and long-term survival rate of the prosthesis in the osteoporotic bone bed without increasing the complexity of the surgery, providing an external hip replacement solution for elderly osteoporosis patients that preserves bone mass and provides better functional recovery.

[0021] In some specific embodiments, the acetabular cup 1 is made of ultra-high molecular weight polyethylene (UHMWPE), and the ball head 2 is made of cobalt-chromium-molybdenum alloy (CoCrMo).

[0022] In some specific embodiments, the inner surface of the acetabular cup 1 and the outer surface of the ball head 2 are both smooth spherical surfaces. The acetabular cup 1 has a spherical notch smaller than a hemisphere, and the ball head 2 has a spherical crown larger than a hemisphere. The centers of the inner surface of the acetabular cup 1 and the outer surface of the ball head 2 are the same. The shape of the acetabular cup 1 and the ball head 2 is designed so that when the acetabular cup 1 and the ball head 2 are connected, the connection position is not located at the maximum diameter of the acetabular cup 1 and the ball head 2, which can avoid jamming when the ball head 2 is inserted into the acetabular cup 1 and facilitate the assembly of the ball head 2 and the acetabular cup 1.

[0023] In some specific embodiments, the central angle corresponding to the arc length of the inner surface of the acetabular cup 1 is approximately 170°, the adaptable surface is replaced with a metal femoral head, the wall thickness of the acetabular cup 1 is less than or equal to 3 mm, preferably 2.5 mm–3.0 mm, and the outer diameter of the acetabular cup 1 is 38 mm–54 mm.

[0024] In some specific embodiments, the groove structure includes several parallel circumferential grooves 3, which are parallel to the opening end of the acetabular cup 1. The circumferential grooves 3 are 1.8 mm–2.0 mm wide and 1.5 mm–2.0 mm deep. The number of circumferential grooves 3 can be set according to needs, generally 3–4. The circumferential grooves 3 are used for the fitting of bone cement during surgery to achieve macroscopic anti-rotation and anti-dislodgement.

[0025] In some specific embodiments, the groove structure further includes a plurality of longitudinal grooves 4, the longitudinal grooves 4 being 1.8 mm–2.0 mm wide and 1.5 mm–2.0 mm deep. The longitudinal grooves 4 are arranged perpendicularly to the circumferential grooves 3, and the longitudinal grooves 4 and the circumferential grooves 3 are connected at their intersections, thereby enhancing the adhesion of the bone cement.

[0026] In some specific embodiments, there are several bosses 5, which are evenly distributed along the circumferential and longitudinal directions on the surface of the acetabular cup 1. The circumferential direction refers to the direction parallel to the circumferential groove 3, and the longitudinal direction refers to the direction parallel to the longitudinal groove 4. The surface of the bosses 5 is a plane. The distance between any position on the surface of the bosses 5 and the center of the acetabular cup 1 gradually increases from the position on the surface of the bosses 5 near the apex of the acetabular cup 1 to the position on the surface of the bosses 5 away from the apex of the acetabular cup 1. The maximum distance between the surface of the bosses 5 and the outer surface of the acetabular cup 1 is 1.2 mm–1.5 mm. Figure 8 Follow the indicated direction. Figure 8 In this embodiment, the line perpendicular to the plane containing the opening of the acetabular cup 1 and passing through the center of the acetabular cup 1 is a vertical line, and the angle α between the surface of the boss 5 and the vertical line is 30°–45°. In this embodiment, the boss 5 can form a locking structure after the bone cement is pressed into the acetabular cup 1 during surgery, which prevents the prosthesis from retracting and resists rotation.

[0027] In some specific embodiments, the ball head 2 adopts an over-radius design, that is, the diameter of the ball head 2 is larger than the diameter of the standard femoral head. Preferably, the radius R of the ball head 2 is 4%–6% larger than the radius of the standard femoral head, that is, R=23 mm–24 mm. This setting can increase the joint containment angle to 165° and the joint flexion to 125°.

[0028] In some specific embodiments, 4–8 anti-rotation grooves 6 are uniformly arranged circumferentially along the inner wall of the ball head 2. The size of one end of the anti-rotation groove 6 is larger than the size of the other end of the anti-rotation groove 6, and the anti-rotation groove 6 extends from the open end of the ball head 2 away from the open end of the ball head 2. The width of the anti-rotation groove 6 is 0.8 mm–1.2 mm, and the depth is 0.5 mm–0.8 mm. Preferably, the width of the anti-rotation groove 6 is 1 mm, and the depth is preferably 0.6 mm. The number of anti-rotation grooves 6 is preferably six. The anti-rotation grooves 6 are used to fit with bone cement. After the bone cement has cured, the anti-rotation grooves 6 can form an internal lock, providing anti-rotation capability.

[0029] In some specific embodiments, the axis of the mandrel 7 passes through the center of the ball head 2. One end of the mandrel 7 is connected to the ball head 2, and the other end of the mandrel 7 is located outside the ball head 2. The mandrel 7 has a taper of 1:15–1:25, preferably 1:20, and the size of one end of the mandrel 7 is larger than the size of the other end. The thread structure 8 is a transverse thread that extends along the axis of the mandrel 7. The thread cross-section of the thread structure 8 is trapezoidal, the pitch is 0.8 mm–1.2 mm, preferably 1 mm, and the tooth height is 0.5 mm. During the operation, the femoral head cancellous bone is rotated and screwed in. After the bone cement is injected, the thread gap is filled, forming a composite anchoring form of "thread-bone cement-cancellous bone".

[0030] In some specific embodiments, the inner wall of the ball head 2 is tapered, and the inner wall of the ball head 2 contracts from the outside to the inside from the opening direction to the closing direction. Figure 12 Taking the direction as a reference, the inner wall of the ball head 2 slopes from top to bottom and from inside to outside, forming an outward expansion structure. That is, the distance between the inner wall of the ball head 2 and the mandrel 7 gradually increases from top to bottom, which can reduce the amount of femoral head grinding. In actual use, only cartilage and 1 mm–2 mm of sclerotic bone need to be removed.

[0031] When performing surgery using the surface hip replacement prosthesis 100 of this embodiment, the specific steps include: Step 1: Femoral head cleaning, the femoral head medullary cavity is reamed in a conical shape to match the diameter of the mandrel 7; Step 2: Mix PMMA bone cement (polymethyl methacrylate bone cement) to the filament-drawing stage and inject it into the femoral head medullary cavity; Step 3: Screw the mandrel 7 of the ball head 2 into the femoral head medullary cavity containing bone cement until the torque of the ball head 2 is ≥2 N·m. The bone cement is squeezed out from the thread gap of the thread structure 8 of the mandrel 7 and fills the groove. Step 4: Rake the acetabulum step by step, preserving the subchondral bone; Step 5: Inject bone cement into the acetabulum and press in the acetabular cup 1. The boss 5 ensures that the thickness of the bone cement layer is 2 mm–2.5 mm. Step 6: Reposition the bone cement after it has hardened.

[0032] This embodiment, through its groove structure and boss 5, increases the pull-out strength of the prosthesis by 42% and the rotational torque by 38% on the acetabular side. The acetabular cup 1 in this embodiment has a wall thickness ≤3 mm, reducing bone resection by approximately 30% compared to traditional total hip cups. The ball head 2 in this embodiment features an over-radius design, increasing the flexion angle by 15° and reducing the dislocation rate to below 0.5%. The mandrel 7 and anti-rotation groove 6 in this embodiment allow for early subsidence <0.5 mm and a rotational loosening torque >12 N·m, 2.4 times that of a traditional smooth mandrel. This embodiment's surface hip replacement prosthesis 100 comprises only two structures: the acetabular cup 1 and the ball head 2, reducing surgical time by approximately 20%. The shear strength at the bone cement-prosthesis interface is increased to 10.5 MPa, significantly reducing the risk of fragmentation and slippage, making it particularly suitable for patients with severe osteoporosis and a T-score ≤ -3.0, thus expanding the indications for surface replacement.

[0033] In this embodiment, the acetabular cup 1, with a wall thickness ≤3 mm, can achieve both anti-dislocation and anti-rotation functions. The ball head 2 with an extra-radius design increases joint coverage, reduces neck-cup impact, and improves mobility. On the femoral head side, the mandrel 7 with a tapered and threaded structure 8 works in conjunction with the anti-rotation groove 6 on the inner wall to enhance the holding force of bone cement and reduce the risk of early subsidence and rotational loosening. The prosthesis contains only two components: the acetabulum and the ball head 2, simplifying the surgical procedure and reducing bone loss.

[0034] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, 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, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0035] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] If this invention discloses or relates to components or structural parts that are fixedly connected to each other, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws) or a non-detachable fixed connection (e.g., riveting, welding). Of course, a fixed connection can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0037] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0038] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0039] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0040] It should also be noted that in the embodiments of this application, the same reference numerals are used to denote the same component or the same part.

[0041] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0042] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A surface-mount hip replacement prosthesis, characterized in that: include: The acetabular cup and the ball head are provided. The ball head is located in the acetabular cup and can rotate relative to the acetabular cup. The acetabular cup is provided with a groove structure and a boss on its outside. The inner wall of the ball head is provided with an anti-rotation groove, and the ball head is provided with a mandrel with a threaded structure inside.

2. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The groove structure includes several parallel circumferential grooves.

3. The surface-mount hip replacement prosthesis according to claim 2, characterized in that: The groove structure also includes several longitudinal grooves, which are arranged perpendicularly to the circumferential grooves, and the longitudinal grooves and the circumferential grooves are connected at their intersections.

4. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The surface of the boss is a plane, and the distance between any position on the surface of the boss and the center of the acetabular cup gradually increases from the position on the surface of the boss near the vertex of the acetabular cup to the position on the surface of the boss away from the vertex of the acetabular cup.

5. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: A plurality of anti-spin grooves are uniformly arranged along the inner wall of the ball head. The size of one end of the anti-spin groove is larger than the size of the other end of the anti-spin groove. The anti-spin groove extends from one end of the ball head to the other end of the ball head in a direction away from the opening end of the ball head.

6. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The axis of the mandrel passes through the center of the ball head, one end of the mandrel is connected to the ball head, the other end of the mandrel is located outside the ball head, the mandrel has a taper, and the size of one end of the mandrel is larger than the size of the other end of the mandrel; the thread structure extends along the axis of the mandrel.

7. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The diameter of the ball head is larger than that of a standard femoral head; the inner wall of the ball head is tapered, and the inner wall of the ball head contracts from the outside to the inside from the open end of the ball head to the closed end of the ball head.

8. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The inner surface of the acetabular cup and the outer surface of the ball head are both smooth spherical surfaces; the acetabular cup has a spherical notch smaller than a hemisphere, and the ball head has a spherical crown larger than a hemisphere.

9. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The wall thickness of the acetabular cup is less than or equal to 3 mm.

10. The surface-mount hip replacement prosthesis according to claim 1, characterized in that: The acetabular cup is made of ultra-high molecular weight polyethylene, and the ball head is made of cobalt-chromium-molybdenum alloy.

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