Hip Prosthesis Femoral Stem System

Abstract

The present invention discloses a hip prosthesis femoral stem system, which belongs to the technical field of orthopedic implants. The hip prosthesis femoral stem system includes a plurality of femoral stems with gradually increasing stem lengths, and the femoral stem has a first proximal position P1. At the position P1, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D1, and the range of D1 is 8.7-28.9. The hip prosthesis femoral stem system of the present invention is suitable for the ratio of the size of the human medullary cavity, can perform effective proximal medial press-fitting, and obtain good postoperative effects.

Description

Technical Field

[0001] The invention relates to the technical field of orthopedic implants, in particular to a hip joint prosthesis femoral stem system. Background Art

[0002] For the cemented femoral stem of hip prosthesis, the distal end is closely engaged with the vertebral body, and the inadequate contact between the proximal medial side and the bone is not a big problem, because the cement can provide additional rotational stability. However, for the biological femoral stem of hip prosthesis (i.e., cementless femoral stem), the press fit between the femoral stem and the natural bone is very important. If the distal taper press fit occurs before its proximal surface contacts the bone, the femoral stem may have unstable bone fixation. Therefore, for the cementless femoral stem, the press fit between its proximal medial side and the natural bone is important.

[0003] During the research process, the inventors found that due to the different shapes of the femoral medullary cavity of each person, the matching of the femoral stem may occur at any part of the stem. The design of the femoral stem prosthesis in the prior art cannot determine the optimal matching of the femoral stem. When the distal end of the femoral stem is matched, the proximal inner side may still not be tightly pressed against the natural bone. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a hip joint prosthesis femoral stem system which is suitable for the ratio of the size of the human medullary cavity and can perform effective proximal medial press-fitting.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A hip joint prosthesis femoral stem system comprises a plurality of femoral stems with gradually increasing stem lengths, wherein:

[0007] The femoral stem has a first proximal position P1. At the position P1, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D1, and the range of D1 is 8.7-28.9.

[0008] Furthermore, the junction between the uppermost edge of the inner side of the femoral stem body and the bone is taken as the initial position, and the first position P1 is within 0-40 mm from the initial position toward the distal end of the femoral stem.

[0009] Furthermore, the first position P1 is the initial position.

[0010] Furthermore, when the femoral stem is rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the value of D1 gradually decreases as the angle increases.

[0011] Furthermore, within an angle range of 0°-15° rotated clockwise or counterclockwise about the center plane, the value range of D1 is 17.6-28.9.

[0012] Further, when the center plane is rotated 0° clockwise or counterclockwise, the value range of D1 is 19.3-28.9.

[0013] Furthermore, when the center plane is rotated 15° clockwise or counterclockwise, the value range of D1 is 17.6-25.6.

[0014] Furthermore, there is a second position P2 within 0-40mm from the initial position toward the distal end of the femoral stem, and the second position P2 is located below the first position P1. At the position P2, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D2, and the range of D2 is 12.6-21.8.

[0015] Further, the second position P2 is a position 10 mm from the initial position toward the distal end of the femoral stem;

[0016] And / or, within the angular range of 0°-15° rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the value range of D2 is 12.6-21.8.

[0017] Furthermore, there is a third position P3 within 0-40mm from the initial position toward the distal end of the femoral stem, and the third position P3 is located below the second position P2. At the position P3, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D3, and the range of D3 is 8.7-16.9.

[0018] Further, the third position P3 is 20 mm from the initial position toward the distal end of the femoral stem;

[0019] And / or, within the angular range of 0°-15° rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the value range of D3 is 8.7-16.9.

[0020] Furthermore, when the center plane is rotated clockwise or counterclockwise by the same angle, the values ​​of D1, D2 and D3 corresponding to the positions P1, P2 and P3 decrease in sequence.

[0021] Furthermore, when the femoral stem is rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the ratio of D1 to D2 gradually decreases as the angle increases, and / or, at 0 degrees, the ratio of D1 to D2 is in the range of 1.21-1.50, at 15 degrees, the ratio of D1 to D2 is in the range of 1.12-1.39, and at 20 degrees, the ratio of D1 to D2 is in the range of 1.06-1.37.

[0022] Furthermore, when the femoral stem is rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the ratio of D1 to D3 gradually decreases as the angle increases, and / or, at 0 degrees, the ratio of D1 to D3 is in the range of 1.45-2.07, at 15 degrees, the ratio of D1 to D3 is in the range of 1.30-1.95; at 20 degrees, the ratio of D1 to D3 is in the range of 1.20-1.88.

[0023] The present invention has the following beneficial effects:

[0024] The hip prosthesis femoral stem system of the present invention includes a plurality of femoral stems with gradually increasing stem lengths, the femoral stem having a first proximal position P1, the distance from the central axis of the femoral stem body to the inner edge of the stem body at the P1 position is D1, and the range of D1 is 8.7-28.9, so that the femoral stem is more suitable for the size of the human medullary cavity, and the proximal matching design is well performed, so that the proximal end can also be well press-fitted, the strain energy density of the proximal end is increased, bone growth is stimulated, and the prosthesis is not prone to loosening, which is particularly beneficial for the long-term fixation of cementless femoral stems. The hip prosthesis femoral stem of the present invention is suitable for the width of the human medullary cavity size, and can be effectively press-fitted on the proximal medial side in the fixation of cementless femoral stems, thereby obtaining good postoperative effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the mechanical properties of a femoral stem of a hip joint prosthesis after implantation into a human body in the prior art;

[0026] Figure 2 Schematic diagram of the measurement position of the femoral stem of the hip joint prosthesis in the present invention Figure 1 ;

[0027] Figure 3 Schematic diagram of the measurement position of the femoral stem of the hip joint prosthesis in the present invention Figure 2 ;

[0028] Figure 4 Schematic diagram of the measurement position of the femoral stem of the hip joint prosthesis in the present invention Figure 3 ;

[0029] Figure 5 Schematic diagram of the measurement position of the femoral stem of the hip joint prosthesis in the present invention Figure 4;

[0030] Figure 6 Schematic diagram of the measurement position of the femoral stem of the hip joint prosthesis in the present invention Figure 5 ;

[0031] Figure 7 It is a schematic diagram of the top view of the structure of the femoral stem of the hip joint prosthesis of the present invention after being implanted into a human body;

[0032] Figure 8 It is a schematic diagram of the mechanical properties of the femoral stem of the hip joint prosthesis of the present invention after being implanted into the human body. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0034] In current hip surgery, different types of intramedullary rasps are usually inserted into the intramedullary cavity in sequence, and the size of the femoral stem prosthesis required is determined by the type of intramedullary rasps (the femoral stem prosthesis is the same size as the intramedullary rasps); during use during surgery, the smallest intramedullary rasps are selected first, and then gradually increased in size. When the intramedullary rasps cannot move forward after percussion (i.e., axial stability), percussion can be stopped, and the size of the femoral stem prosthesis required can be determined at this time. However, traditional femoral stem prostheses are prone to the phenomenon of the distal end of the prosthesis being stuck in the intramedullary cavity, resulting in a large gap at the proximal end. This gap greatly affects the press fit of the proximal stem on the proximal cortical bone, making the strain energy density of the proximal cortical bone very low ( Figure 1 The arrow in (a) shows that the proximal gap is larger. Figure 1 The arrows in (b) and (c) show that the strain energy density is low), which does not receive good stimulation and is prone to bone absorption, leading to proximal bone dissolution and prosthesis loosening.

[0035] The present invention provides a hip joint prosthesis femoral stem system, such as Figure 2-8 As shown, it includes a plurality of femoral stems with gradually increasing stem lengths (the femoral stem includes a stem body 1 and a femoral neck 2), wherein:

[0036] The femoral stem has a first proximal position P1. At the position P1, the distance from the central axis of the femoral stem body 1 to the inner edge of the stem body 1 is D1, and the range of D1 is 8.7-28.9.

[0037] The hip prosthesis femoral stem system of the present invention includes a plurality of femoral stems with gradually increasing stem lengths, the femoral stem having a first proximal position P1, the distance from the central axis of the femoral stem body to the inner edge of the stem body at the P1 position is D1, and the range of D1 is 8.7-28.9, so that the femoral stem is more suitable for the size of the human medullary cavity, and the proximal matching design is well performed, so that the proximal end can be well press-fitted, the strain energy density of the proximal end is increased, bone growth is stimulated, and the prosthesis is not prone to loosening, which is particularly beneficial for the long-term fixation of cementless femoral stems. The hip prosthesis femoral stem of the present invention is suitable for the width of the human medullary cavity size, and can be effectively press-fitted on the proximal medial side in the fixation of cementless femoral stems, thereby obtaining good postoperative effects.

[0038] Preferably, Figure 2-6 As shown, the uppermost edge of the inner side of the femoral stem body 1 and the bone junction are taken as the initial position ( Figure 2-6 The first position P1 is located within 0-40 mm from the initial position (0 mm position) to the distal end of the femoral stem. In a specific implementation, the first position P1 may be the initial position.

[0039] In order to better define the size of the femoral stem, the present invention preferably takes other positions besides the P1 position within 0-40 mm, and further defines the size change of the femoral stem through other positions besides the P1 position, so as to better fit the ratio of the human medullary cavity size. In specific implementation, for example:

[0040] like Figure 2-6 As shown, there can also be a second position P2 within 0-40mm from the initial position to the distal end of the femoral stem, the second position P2 is located below the first position P1, and the distance from the central axis of the femoral stem body 1 to the inner edge of the stem body 1 at the P2 position is D2, and the range of D2 is 12.6-21.8. In specific implementation, the second position P2 can be 10mm from the initial position to the distal end of the femoral stem.

[0041] like Figure 2-6 As shown, there can also be a third position P3 within 0-40mm from the initial position to the distal end of the femoral stem, and the third position P3 is located below the second position P2. At the position P3, the distance from the central axis of the femoral stem body 1 to the inner edge of the stem body 1 is D3, and the range of D3 is 8.7-16.9. In specific implementation, the third position P3 can be 20mm from the initial position to the distal end of the femoral stem.

[0042] It can be understood that the positions of P1, P2 and P3 can be any other position within 0-40mm from the initial position toward the distal end of the femoral stem, such as 5mm (P4 position in the figure, the corresponding distance from the central axis of the femoral stem body 1 to the inner edge of the stem body 1 is D4), 11mm, 12mm, 13mm, 15mm (P5 position in the figure, the corresponding distance from the central axis of the femoral stem body 1 to the inner edge of the stem body 1 is D5), 35mm position, etc.

[0043] In addition, the inventors discovered during the research process that due to the different shapes of the femoral medullary cavity of each person, the matching of the femoral stem does not necessarily occur on the coronal plane, but may occur in the three-dimensional space near the coronal plane. It is far from enough to study it only in two-dimensional space. It is not suitable for the ratio of the human medullary cavity size in three-dimensional space, and it is impossible to determine the optimal matching of the femoral stem. When the distal end of the femoral stem is matched, the proximal inner side and the natural bone may still not be tightly pressed together.

[0044] To solve this problem, Figure 7 As shown, in the present invention, preferably the coronal plane M where the femoral stem is located is rotated clockwise or counterclockwise as the center plane, and as the angle α increases, the value of D1 gradually decreases. Here, the value of α can be flexibly selected according to needs, and the value range can be 0-30 degrees, for example, 20 degrees.

[0045] In this way, by setting different femoral stem size values ​​for prostheses of different sizes within at least 20 degrees centered on the coronal plane in three-dimensional space, and determining the best match for the femoral stem through the values, the proximal medial press-fit can be achieved for each population to the greatest extent possible, thereby avoiding the situation where only the distal end of the femoral stem in the cementless hip prosthesis is matched.

[0046] Further, within the angular range of 0°-15° rotated clockwise or counterclockwise about the center plane, the value range of D1 is preferably 17.6-28.9.

[0047] Specifically, as shown in Table 1, according to the different clockwise or counterclockwise rotation angles of the center plane, the values ​​of D1 can be as follows:

[0048] When the rotation angle α is 0° (i.e., no rotation), the value range of D1 is 19.3-28.9;

[0049] When the rotation angle α is 3°, the value range of D1 is 19.2-28.6;

[0050] When the rotation angle α is 5°, the value range of D1 is 19.1-28.3;

[0051] When the rotation angle α is 8°, the value range of D1 is 18.8-27.3;

[0052] When the rotation angle α is 12°, the value range of D1 is 18.3-26.5;

[0053] When the rotation angle α is 15°, the value range of D1 is 17.6-25.6.

[0054] The hip prosthesis femoral stem of the present invention is explained below with a specific example. The present invention is particularly suitable for non-bone cement type hip prosthesis femoral stem, and is explained below with the non-bone cement type hip prosthesis femoral stem as an example, wherein the numerical range of D1 at the first position P1 is defined in a spatial plane rotated clockwise and counterclockwise by a certain angle with the coronal plane where the hip prosthesis femoral stem is located as the center plane in three-dimensional space, so as to achieve a better match. At the same time, in the present invention, the femoral stem can be divided into different models according to different stem lengths, and the stem length of the femoral stem can refer to the medial stem length, that is, the distance from the initial position to the lowest end of the stem body 1. In the present embodiment, the hip prosthesis femoral stem system includes a total of ten femoral stem prostheses according to the different stem length ranges. In other embodiments, the number of femoral stem prostheses can be adaptively increased or decreased according to different actual use requirements.

[0055] The numerical range of D1 of the femoral stem of the cementless hip prosthesis in this embodiment is preferably as shown in Table 1 below.

[0056] Table 1

[0057]

[0058]

[0059] Furthermore, within the angular range of 0°-15° rotated clockwise or counterclockwise with the coronal plane M where the femoral stem is located as the center plane, the numerical range of D2 is preferably 12.6-21.8.

[0060] Specifically, as shown in Table 2, according to the different clockwise or counterclockwise rotation angles of the center plane, the values ​​of D2 can be as follows:

[0061] When the rotation angle α is 0° (i.e., no rotation), the value range of D2 is 13.4-21.8;

[0062] When the rotation angle α is 3°, the value range of D2 is 13.3-21.7;

[0063] When the rotation angle α is 5°, the value range of D2 is 13.3-21.6;

[0064] When the rotation angle α is 8°, the value range of D2 is 13.3-21.5;

[0065] When the rotation angle α is 12°, the value range of D2 is 13.0-21.1;

[0066] When the rotation angle α is 15°, the value range of D2 is 12.6-20.7.

[0067] The numerical range of D2 of the femoral stem of the cementless hip prosthesis in this embodiment is preferably as shown in Table 2 below.

[0068] Table 2

[0069]

[0070] Furthermore, within the angular range of 0°-15° rotated clockwise or counterclockwise with the coronal plane M where the femoral stem is located as the center plane, the numerical range of D3 is preferably 8.7-16.9.

[0071] Specifically, as shown in Table 3, according to the different clockwise or counterclockwise rotation angles of the center plane, the values ​​of D3 can be as follows:

[0072] When the rotation angle α is 0° (i.e., no rotation), the value range of D3 is 8.9-16.9;

[0073] When the rotation angle α is 3°, the value range of D3 is 8.9-16.9;

[0074] When the rotation angle α is 5°, the value range of D3 is 8.9-16.8;

[0075] When the rotation angle α is 8°, the value range of D3 is 8.8-16.7;

[0076] When the rotation angle α is 12°, the value range of D3 is 8.8-16.6;

[0077] When the rotation angle α is 15°, the value range of D3 is 8.7-16.4.

[0078] The numerical range of D3 of the femoral stem of the cementless hip prosthesis in this embodiment is preferably as shown in Table 3 below.

[0079] Table 3

[0080]

[0081]

[0082] It can be understood that the rotation angle α can be any angle between 0° and 15° in three-dimensional space, such as 2 degrees, 4 degrees, 6 degrees, 10 degrees, 13 degrees, etc.

[0083] The numerical ranges for other positions on the coronal plane at the center of the femoral stem are preferably as shown in Table 4-5 below.

[0084] Table 4

[0085]

[0086] Table 5

[0087]

[0088]

[0089] Tables 1-5 above provide a femoral stem design that is more suitable for the width of the human medullary cavity, and give recommendations for the size of each femoral stem model. In addition, it can be seen from the table that as the femoral stem model / size increases, the values ​​at each angle gradually increase. Both stem types in the above table are medium-long stems. In other embodiments, other stem types such as long stems or short stems can also be set.

[0090] Preferably, when the center plane is rotated clockwise or counterclockwise by the same angle, the values ​​of D1, D2 and D3 corresponding to the positions P1, P2 and P3 decrease in sequence.

[0091] In order to make the femoral stem more suitable for the width of the human medullary cavity and to better design the proximal matching, the femoral stem is rotated clockwise or counterclockwise with the coronal plane M where the femoral stem is located as the center plane. As the angle increases, the ratio of D1 to D2 preferably decreases gradually. At 0 degrees, the ratio of D1 to D2 ranges from 1.21 to 1.50, at 15 degrees, the ratio of D1 to D2 ranges from 1.12 to 1.39; at 20 degrees, the ratio of D1 to D2 ranges from 1.06 to 1.37.

[0092] Furthermore, when the femoral stem is rotated clockwise or counterclockwise with the coronal plane M where the femoral stem is located as the center plane, as the angle increases, the ratio of D1 to D3 preferably decreases gradually. At 0 degrees, the ratio of D1 to D3 is in the range of 1.45-2.07, at 15 degrees, the ratio of D1 to D3 is in the range of 1.30-1.95; at 20 degrees, the ratio of D1 to D3 is in the range of 1.20-1.88.

[0093] The study found that the characteristics of the numerical changes in the human medullary cavity are as follows: whether at the 0mm position (i.e. P1), 10mm position (P2), or 20mm position (P3), the 0 degree and ±3 degree values ​​of the human body are relatively close, the ±5 degree value is slightly reduced, and the ±8 degree value and the ±10 degree value gradually decrease on the basis of the ±5 degree value.

[0094] The above-mentioned changes in the ratio of D1 to D2 and the ratio of D1 to D3 are designed according to the laws of the human medullary cavity to change the shape of the prosthesis, which is more suitable for the size of the human medullary cavity. In the fixation of the cementless femoral stem, effective proximal medial compression can be performed in three-dimensional space to obtain good postoperative results.

[0095] In the present invention, the femoral stem of the cementless hip prosthesis can be any conventional structure in the art. In one embodiment, Figure 4-5 As shown, the femoral stem of the non-bone cement hip prosthesis can be a fully coated femoral stem, the stem body 1 is provided with a coating and a groove (the groove can include a long strip groove located at the distal side of the stem body 1 to increase the contact area), and the stem body 1 is a rectangular double-tapered stem. In another embodiment, as Figure 6 As shown, the handle body 1 is provided with grooves and vertical ridges, and the grooves of the handle body 1 can increase the contact area. Preferably, there are 2-4 vertical ridges, which can be embedded in the cancellous bone to stabilize and fix the femoral stem. At the same time, the distal lateral notch of the handle body 1 facilitates the implantation of the femoral stem.

[0096] After testing, Figure 1 As shown, the prior art, that is, the proximal gap of the femoral stem of the cementless hip prosthesis before improvement is large, the strain energy density is low, bone absorption is prone to occur, 72.5% of them are poorly matched, and there is a large gap at the proximal end; Figure 8 As shown, the present invention Figure 2-7 For the cementless hip prosthesis femoral stem shown in Table 1-5, the above 72.5% produced a good press fit at the proximal end without changing the distal size, and the strain energy density was high, which was conducive to bone growth, resulting in a good match for the vast majority of people, bringing the overall good match rate to 98%.

[0097] It can be seen from this that the present invention provides a more suitable medullary cavity setting option for real people, so that in cementless stem fixation, effective proximal medial press-fitting can be performed in three-dimensional space to obtain good postoperative results.

[0098] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hip prosthesis femoral stem system, characterized in that: Includes multiple femoral stems with increasing stem lengths, including: The femoral stem has a first proximal position P1, and at the position P1, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D1, and the range of D1 is 8.7-28.9 mm; The uppermost edge of the inner side of the femoral stem and the bone junction is taken as the initial position, and the first position P1 is within 0-40 mm from the initial position to the distal end of the femoral stem; The femoral stem is rotated clockwise or counterclockwise with the coronal plane as the center plane. As the angle increases, the value of D1 gradually decreases. There is also a second position P2 within 0-40mm from the initial position to the distal end of the femoral stem. The second position P2 is located below the first position P1. At position P2, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D2, and the range of D2 is 12.6-21.8mm.

2. The hip prosthesis femoral stem system according to claim 1, characterized in that: The first position P1 is the initial position.

3. The hip prosthesis femoral stem system according to claim 1, characterized in that: In the angular range of 0°-15° rotated clockwise or counterclockwise about the center plane, the value range of D1 is 17.6-28.9 mm.

4. The hip prosthesis femoral stem system according to claim 3, characterized in that: When the center plane is rotated 0° clockwise or counterclockwise, the value range of D1 is 19.3-28.9 mm.

5. The hip prosthesis femoral stem system according to claim 3, characterized in that: When the center plane is rotated 15° clockwise or counterclockwise, the value range of D1 is 17.6-25.6 mm.

6. The hip prosthesis femoral stem system according to claim 1, characterized in that: The second position P2 is 10 mm from the initial position to the distal end of the femoral stem; And / or, within the angular range of 0°-15° rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the value range of D2 is 12.6-21.8 mm.

7. The hip prosthesis femoral stem system according to claim 1, characterized in that: There is also a third position P3 within 0-40mm from the initial position to the distal end of the femoral stem, and the third position P3 is located below the second position P2. At the position P3, the distance from the central axis of the femoral stem body to the inner edge of the stem body is D3, and the range of D3 is 8.7-16.9mm.

8. The hip prosthesis femoral stem system according to claim 7, characterized in that: The third position P3 is 20 mm from the initial position to the distal end of the femoral stem; And / or, within the angular range of 0°-15° rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane, the value range of D3 is 8.7-16.9 mm.

9. The hip prosthesis femoral stem system according to claim 7, characterized in that: When the center plane is rotated clockwise or counterclockwise by the same angle, the values ​​of D1, D2 and D3 corresponding to the positions P1, P2 and P3 decrease in sequence.

10. The hip prosthesis femoral stem system according to claim 1, characterized in that: The femoral stem is rotated clockwise or counterclockwise with the coronal plane where the femoral stem is located as the center plane. As the angle increases, the ratio of D1 to D2 gradually decreases, and / or, at 0 degrees, the ratio of D1 to D2 is in the range of 1.21-1.50, at 15 degrees, the ratio of D1 to D2 is in the range of 1.12-1.39, and at 20 degrees, the ratio of D1 to D2 is in the range of 1.06-1.

37.

11. The hip prosthesis femoral stem system according to claim 7, characterized in that: With the coronal plane where the femoral stem is located as the center plane, the ratio of D1 to D3 gradually decreases as the angle increases, and / or, at 0 degrees, the ratio of D1 to D3 is in the range of 1.45-2.07, at 15 degrees, the ratio of D1 to D3 is in the range of 1.30-1.95; at 20 degrees, the ratio of D1 to D3 is in the range of 1.20-1.88.

Images