Hip prosthesis femoral stem system

Abstract

The invention discloses a hip joint prosthesis femoral stem system, and belongs to the technical field of orthopedic implants, the hip joint prosthesis femoral stem system comprises a plurality of specifications of femoral stem groups, the same specification of femoral stem group comprises two femoral stems with different eccentric distances, and along with the progressive increase of the specifications of the femoral stem groups, the eccentric distances of the two femoral stems are different. The difference value of the eccentric distances of the two femoral stems of the same specification is increased according to a nonlinear expression. The hip joint prosthesis femoral stem system better conforms to human body distribution, and therefore hip joint biomechanics can be better recovered.

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] Hip replacement is a surgery used to treat serious hip disease or injury by removing the damaged hip joint and replacing it with an artificial hip joint. An artificial hip joint usually consists of three parts: the femoral stem, the femoral head, and the acetabulum.

[0003] An important structural parameter of the femoral stem is the eccentricity, which is the distance between the centerline of the stem cone and the stem body. The eccentricity will affect the stability and range of motion of the artificial hip joint, so it needs to be selected and adjusted according to the patient's anatomical structure and functional needs. Generally speaking, the larger the eccentricity, the worse the stability of the artificial hip joint, but the larger the range of motion; the smaller the eccentricity, the better the stability of the artificial hip joint, but the smaller the range of motion.

[0004] The influence of eccentricity has been taken into consideration in the design of existing femoral stems. Existing femoral stems generally have two eccentricities, one is standard eccentricity and the other is high eccentricity, so as to better restore the eccentricity of the patient and the biomechanics of the hip joint. Compared with the femoral stem with standard (i.e. ordinary) eccentricity, the high eccentricity femoral stem of the same specification has the same stem body and neck height, and only the eccentricity changes (such as Figure 1 shown).

[0005] However, in the existing femoral stem, when setting the high eccentricity and the ordinary eccentricity, the difference between the high eccentricity and the ordinary eccentricity is generally fixed. The inventor found during the research process that the difference between the high eccentricity and the ordinary eccentricity should be slightly smaller on a small-sized femoral stem, and slightly larger on a large-sized femoral stem, so that it is more in line with the distribution of the human body, thereby better restoring the biomechanics of the hip joint. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a hip prosthesis femoral stem system which is more in line with the distribution of the human body and can better restore the biomechanics of the hip joint.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A hip prosthesis femoral stem system includes a plurality of femoral stem groups of different specifications. The femoral stem group of the same specification includes two femoral stems with different eccentricities. As the specification of the femoral stem group increases, the difference in eccentricity between the two femoral stems of the same specification increases according to a nonlinear expression.

[0009] Further, the difference Δd between the eccentricities of the two femoral stems satisfies the following exponential function:

[0010] Ad=a·bx x

[0011] Wherein, a and b are constants, x is the specification number of the femoral stem set, and x is an integer greater than or equal to 1.

[0012] Furthermore, the difference Δd between the eccentricities of the two femoral stems satisfies the following piecewise exponential function:

[0013]

[0014] Among them, a i and b i are all constants, i is the total number of segments, x is the specification number of the femoral stem group, x is an integer greater than or equal to 1, and n i Is the end point of the segment.

[0015] Further, the difference Δd between the eccentricities of the two femoral stems satisfies the following logarithmic function:

[0016] Δd=a+bln(x)

[0017] Wherein, a and b are constants, x is the specification number of the femoral stem set, and x is an integer greater than or equal to 1.

[0018] Furthermore, the difference Δd between the eccentricities of the two femoral stems satisfies the following piecewise logarithmic function:

[0019]

[0020] Among them, a i and b i are all constants, i is the total number of segments, x is the specification number of the femoral stem group, x is an integer greater than or equal to 1, and n i Is the end point of the segment.

[0021] Furthermore, the difference Δd between the eccentricities of the two femoral stems of the smallest femoral stem group is min Between 3mm-5.5mm.

[0022] Furthermore, the difference Δd between the eccentricities of the two femoral stems of the largest femoral stem group is max Between 6.5mm-9mm.

[0023] Furthermore, as the specifications of the femoral stem set increase, the growth rate of the eccentricity of the two femoral stems is 5%-15%.

[0024] Furthermore, the specifications of the femoral stem set range from 8 to 16;

[0025] and / or, b or b i is equal to 1.

[0026] Further, the proximal end of the femoral stem is provided with a coating and a vertical groove;

[0027] and / or, the mid-distal end of the femoral stem is conical;

[0028] And / or, the entire stem body of the femoral stem is a rectangular double-tapered stem.

[0029] The present invention has the following beneficial effects:

[0030] The hip prosthesis femoral stem system of the present invention includes femoral stem groups of multiple specifications. The femoral stem group of the same specification includes two femoral stems with different eccentricities. As the specification of the femoral stem group increases, the difference in eccentricity of the two femoral stems of the same specification increases according to a nonlinear expression, which can better adapt to the eccentricity requirements of femoral stems of different specifications, thereby better restoring the biomechanics of the hip joint, improving the stability and range of motion of the artificial hip joint, extending the life of the artificial hip joint, reducing the occurrence of complications, and improving the quality of life of patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram comparing the high eccentricity and the normal eccentricity of the femoral stem in the present invention;

[0032] Figure 2 Another schematic diagram comparing the high eccentricity and the normal eccentricity of the femoral stem in the present invention;

[0033] Figure 3 It is a schematic diagram of the dimensional relationship between the high eccentricity and the normal eccentricity of the femoral stem in the present invention. DETAILED DESCRIPTION

[0034] 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.

[0035] The present invention provides a hip joint prosthesis femoral stem system, such as Figure 1-3 As shown, a femoral stem group includes multiple specifications. The femoral stem group under the same specification includes two femoral stems with different eccentricities. As the specification of the femoral stem group increases, the difference in eccentricity of the two femoral stems under the same specification increases according to a nonlinear expression, that is, between the two femoral stems under the same specification, the difference Δd between the high eccentricity d' of one femoral stem and the ordinary eccentricity d of the other femoral stem increases according to a nonlinear expression.

[0036] The hip prosthesis femoral stem system of the present invention includes femoral stem groups of multiple specifications. The femoral stem group of the same specification includes two femoral stems with different eccentricities. As the specification of the femoral stem group increases, the difference in eccentricity of the two femoral stems of the same specification increases according to a nonlinear expression, which can better adapt to the eccentricity requirements of femoral stems of different specifications, thereby better restoring the biomechanics of the hip joint, improving the stability and range of motion of the artificial hip joint, extending the life of the artificial hip joint, reducing the occurrence of complications, and improving the quality of life of patients.

[0037] The difference Δd between the eccentricities of the two femoral stems (ie, the difference Δd between the high eccentricity d' and the normal eccentricity d) can be increased according to a nonlinear expression in the following manner.

[0038] Implementation method 1:

[0039] The difference in eccentricity of the two femoral stems, Δd, can satisfy the following exponential function:

[0040] △d=a·b x

[0041] Wherein, a and b are constants, x is the specification number of the femoral stem set, and x is an integer greater than or equal to 1.

[0042] When using the above exponential function Δd = a·b x To describe the difference in eccentricity of two femoral stems, a and b are constants that can be adjusted according to actual conditions. By changing the values ​​of a and b, the initial value and growth rate of the eccentricity difference Δd can be changed.

[0043] For example, if you want the initial value of the eccentricity difference Δd to be 3.5mm, and the growth rate is 9% for each additional specification number, then you can take a=3.2, b=1.09, and the formula is Δd=3.2·1.09 x ; If the specification is set to 12 specifications, the results shown in Table 1 below can be obtained (see also Figure 3 ):

[0044] Table 1

[0045]

[0046]

[0047] When designing the femoral stem, the difference range between the high eccentricity d' and the common eccentricity d of the smallest femoral stem group (No. 1 femoral stem) is not fixed. According to existing experience, the difference Δd between the high eccentricity d' and the common eccentricity d of the smallest femoral stem group of different designs is minWhen the eccentricity difference Δd is preferably between 3mm-5.5mm, a good eccentricity adjustment effect can be achieved; with the increase of the femoral stem group specification number, the growth rate b of the eccentricity difference Δd is preferably between 5%-15%, which can achieve a good eccentricity difference distribution. The constant a is a driven value and needs to be adjusted according to the selected Δd min For example, when the difference between the high eccentricity d' and the normal eccentricity d of the smallest femoral stem group is 4 mm, and the growth rate of the eccentricity difference Δd is 10%, the formula can be used as follows: 4 = a·1.1 1 , thus we can obtain a=3.63.

[0048] As the number of femoral stem sets increases, the difference between the high eccentricity d' and the normal eccentricity d gradually increases, but the difference between the high eccentricity d' and the normal eccentricity d is not the larger the better. According to existing experience, when the difference between the high eccentricity d' and the normal eccentricity d of the largest specification femoral stem set is preferably between 6.5mm-9mm, a good eccentricity adjustment effect can be achieved.

[0049] Implementation method 2:

[0050] While keeping the difference between the high eccentricity d' and the ordinary eccentricity d increasing with the specification number of the femoral stem group, sometimes keeping the difference between the high eccentricity d' and the ordinary eccentricity d between two or several specifications the same can make it more convenient to select the femoral stem during surgery; sometimes when the design of the femoral stem group of intermediate specifications is relatively dense, the initial value and growth rate of the eccentricity difference between several specifications can also be adjusted separately, so a piecewise exponential function can be used to describe the difference between the high eccentricity d' and the ordinary eccentricity d, that is:

[0051] The difference Δd between the eccentricities of the two femoral stems can satisfy the following piecewise exponential function:

[0052]

[0053] Among them, a i and b i are all constants and can be adjusted according to actual conditions. i is the total number of segments and can be determined according to needs. x is the specification number of the femoral stem (starting from 1). n i Is the end point of the segment.

[0054] Among them, a i and b i are all constants, i is the total number of segments, x is the specification number of the femoral stem group, x is an integer greater than or equal to 1, and n i Is the end point of the segment.

[0055] When the above piecewise exponential function is used to describe the difference between the high eccentricity d' and the normal eccentricity d, the difference can be expressed by changing a i and b i , to change the initial value and growth rate of the eccentricity difference in different intervals; when it is necessary to make the difference between the high eccentricity d' and the ordinary eccentricity d between two or more specifications the same, as long as the constant b is set in the corresponding interval i When the initial value and growth rate of the eccentricity difference in different intervals need to be changed, change a in the corresponding interval. i and b i The effect can be achieved by setting the value of .

[0056] Example 1: If you want the eccentricity difference to be: when the specification number is 1 to 3, the initial value is 3.5mm, and the growth rate is 12%, that is, the eccentricity difference increases by 12% for each additional specification; when the specification number is 4 to 8, the initial value is 4.6mm, and the growth rate is 7%, that is, the eccentricity difference increases by 7% for each additional specification; when the specification number is 9 to 12, the initial value is 6.5mm, and the growth rate is 11%, that is, the eccentricity difference increases by 11% for each additional specification, then the formula is:

[0057]

[0058] The results shown in Table 2 below can be obtained:

[0059] Table 2

[0060]

[0061]

[0062] Example 2: If you want the eccentricity difference to be: when the specification number is 1 to 4, the initial value is 4mm, and the growth rate is 10%, that is, the eccentricity difference increases by 10% for each additional specification number; when the specification number is 5 to 8, the initial value is 5.6mm, and the growth rate is 0%, that is, as the specification number increases, the eccentricity difference remains unchanged; when the specification number is 9 to 12, the initial value is 6.3mm, and the growth rate is 10%, that is, as the specification number increases, the eccentricity difference increases by 10%, then the formula is:

[0063]

[0064] Then the results shown in Table 3 can be obtained:

[0065] Table 3

[0066] Specification The difference between high eccentricity and normal eccentricity Δd 1# 4.0 2# 4.4 3# 5.0 4# 5.6 5# 5.6 6# 5.6 7# 5.6 8# 5.6 9# 6.2 10# 6.7 11# 7.4 12# 8.1

[0067] Example 3: If you want the eccentricity difference to be: when the specification number is 1 to 4, the initial value is 4mm, and the growth rate is 0%, that is, as the specification increases, the eccentricity difference remains unchanged; when the specification number is 5 to 8, the initial value is 6mm, and the growth rate is 0%, that is, as the specification increases, the eccentricity difference remains unchanged; when the specification number is 9 to 12, the initial value is 8mm, and the growth rate is 0%, that is, as the specification number increases, the eccentricity difference remains unchanged, then the formula is:

[0068]

[0069] Then the results shown in Table 4 can be obtained:

[0070] Table 4

[0071] Specification The difference between high eccentricity and normal eccentricity Δd 1# 4.0 2# 4.0 3# 4.0 4# 4.0 5# 6.0 6# 6.0 7# 6.0 8# 6.0 9# 8.0 10# 8.0 11# 8.0 12# 8.0

[0072] Examples 1 to 3 are only some implementation examples, and segmented adjustment and the initial value and growth rate of the eccentricity difference of each segment can be set according to actual conditions.

[0073] As above, when designing a femoral stem set, the difference range between the high eccentricity d' and the common eccentricity d of the smallest femoral stem set is not fixed. According to existing experience, the difference Δd between the high eccentricity d' and the common eccentricity d of the smallest femoral stem set of different designs is min When it is preferably between 3mm-5.5mm, a good eccentricity adjustment effect can be achieved; when the growth rate b of the eccentricity difference is preferably between 5%-15%, a good eccentricity difference distribution can be achieved; when the difference between the high eccentricity d' and the ordinary eccentricity d of the largest specification femoral stem group is preferably between 6.5mm-9mm, a good eccentricity adjustment effect can be achieved.

[0074] Implementation method three:

[0075] When using an exponential function to express the nonlinear growth of the difference between the high eccentricity d' and the normal eccentricity d with increasing specifications of the femoral stem set, the difference between the high eccentricity d' and the normal eccentricity d gradually increases with the increase of the specification number, and the increasing trend will become faster and faster, which results in that for larger femoral stem sets, the difference between the high eccentricity d' and the normal eccentricity d may exceed the desired 9.5mm.

[0076] Therefore, in the following embodiments, an exponential function or a piecewise exponential function is not used to express the nonlinear growth of the difference between the high eccentricity d' and the common eccentricity d when the femoral stem set specification number increases, but a logarithmic function is used to express the difference between the high eccentricity d' and the common eccentricity d, that is:

[0077] The difference in eccentricity of the two femoral stems, Δd, can satisfy the following logarithmic function:

[0078] Δd=a+bln(x)

[0079] Wherein, a and b are constants and can be adjusted according to actual conditions, x is the specification number of the femoral stem set, and x is an integer greater than or equal to 1.

[0080] The characteristic of the logarithmic function is that the growth of the eccentricity difference is nonlinear. The difference between the high eccentricity d' and the ordinary eccentricity d gradually increases with the increase of the specification number, but the rate of increase is decreasing.

[0081] For example, if you want the initial value of the eccentricity difference to be 5mm, and the growth rate is that the rate of increase of the eccentricity difference decreases from 20% to 0% for each additional specification number, then you can take a=5, b=1, and the formula is Δd=5+ln(x). According to this formula, the difference between the high eccentricity d' and the ordinary eccentricity d of each specification can be calculated, and the results shown in Table 5 below can be obtained:

[0082] Table 5

[0083] Specification The difference between high eccentricity and normal eccentricity Δd 1# 5.0 2# 5.7 3# 6.1 4# 6.4 5# 6.6 6# 6.8 7# 6.9 8# 7.1 9# 7.2 10# 7.3 11# 7.4 12# 7.5

[0084] Implementation method 4:

[0085] While keeping the difference between high eccentricity d' and ordinary eccentricity d increasing with the specification, if it is necessary to keep the difference between high eccentricity d' and ordinary eccentricity d between two or several specification numbers the same or to adjust the initial value and growth rate of the eccentricity difference between several specification numbers separately, the above logarithmic function can also be converted into a piecewise logarithmic function to express the difference between high eccentricity d' and ordinary eccentricity d, that is:

[0086] The difference Δd between the eccentricities of the two femoral stems can satisfy the following piecewise logarithmic function:

[0087]

[0088] Among them, a i and b i are all constants and can be adjusted according to actual conditions. i is the total number of segments and can be determined according to needs. x is the specification number of the femoral stem group. x is an integer greater than or equal to 1. n i Is the end point of the segment.

[0089] The characteristic of the piecewise logarithmic function is that within each segment, the change of the eccentricity difference is a logarithm. The difference between the high eccentricity d' and the ordinary eccentricity d gradually increases with the increase of the specification number, but the rate of increase is decreasing. When it is necessary to make the difference between the high eccentricity d' and the ordinary eccentricity d between two or more specification numbers the same, as long as the constant b is set in the corresponding intervali Equal to 0, the effect can be achieved.

[0090] For example, if you want the eccentricity difference to be 5mm when the specification number is 1 to 3, and the growth rate is that the eccentricity difference decreases between 20% and 10% for each additional specification number; when the specification number is 4 to 6, the initial value is 6mm, and the growth rate is that the eccentricity difference decreases between 10% and 5% for each additional specification number; when the specification number is 7 to 10, the initial value is 7mm, and the growth rate is that the eccentricity difference decreases between 5% and 2% for each additional specification number, then the formula is:

[0091]

[0092] In all the above formulas, the constants a and b can be adjusted according to actual conditions to adjust the initial value and growth rate of the eccentricity difference.

[0093] In the present invention, the femoral stem set may have 8-16 pieces, such as 9, 10, 12, 15, etc. Figure 2 As shown, the proximal end of the femoral stem can be provided with a coating and a vertical groove to increase the contact area; the mid-distal end of the femoral stem can be conical to facilitate implantation; and the entire body of the femoral stem can be a rectangular double-tapered stem.

[0094] In summary, the hip prosthesis femoral stem system of the present invention can achieve a nonlinear growth of the difference between the high eccentricity and the ordinary eccentricity, so that the difference between the high eccentricity and the ordinary eccentricity gradually increases with the increase of the specification number, and while maintaining the overall increase with the specification number, the difference between the high eccentricity and the ordinary eccentricity between two or several specification numbers can also be the same, as long as the constant b is within the corresponding interval. i Equal to 1, this effect can be achieved, and it can be adjusted according to different constants a and b or a i and b i To adjust the initial value and growth rate of the eccentricity difference, so as to better adapt to the anatomical structure and functional requirements of different patients and better improve the stability and range of motion of the artificial hip joint.

[0095] 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: It includes femoral stem sets of multiple specifications. The femoral stem set of the same specification includes two femoral stems with different eccentricities. As the specifications of the femoral stem set increase, the difference in eccentricities of the two femoral stems of the same specification increases according to a nonlinear expression.

2. The hip prosthesis femoral stem system according to claim 1, characterized in that: The difference Δd between the eccentricities of the two femoral stems satisfies the following exponential function: Δd=a·b x Wherein, a and b are constants, x is the specification number of the femoral stem set, and x is an integer greater than or equal to 1.

3. The hip prosthesis femoral stem system according to claim 1, characterized in that: The difference Δd between the eccentricities of the two femoral stems satisfies the following piecewise exponential function: Among them, a i and b i are all constants, i is the total number of segments, x is the specification number of the femoral stem group, x is an integer greater than or equal to 1, and n i Is the end point of the segment.

4. The hip prosthesis femoral stem system according to claim 1, characterized in that: The difference Δd between the eccentricities of the two femoral stems satisfies the following logarithmic function: Δd=a+bln(x) Wherein, a and b are constants, x is the specification number of the femoral stem set, and x is an integer greater than or equal to 1.

5. The hip prosthesis femoral stem system according to claim 1, characterized in that: The difference Δd between the eccentricities of the two femoral stems satisfies the following piecewise logarithmic function: Among them, a i and b i are all constants, i is the total number of segments, x is the specification number of the femoral stem group, x is an integer greater than or equal to 1, and n l Is the end point of the segment.

6. The hip prosthesis femoral stem system according to any one of claims 1 to 5, characterized in that: The difference Δd between the eccentricities of the two femoral stems of the smallest femoral stem set min Between 3mm-5.5mm.

7. The hip prosthesis femoral stem system according to any one of claims 1 to 5, characterized in that: The difference Δd between the eccentricities of the two femoral stems of the largest femoral stem set max Between 6.5mm-9mm.

8. The hip prosthesis femoral stem system according to any one of claims 1 to 5, characterized in that: As the specifications of the femoral stem set increase, the growth rate of the eccentricity of the two femoral stems is 5%-15%.

9. The hip prosthesis femoral stem system according to any one of claims 2 to 5, characterized in that: The specifications of the femoral stem set range from 8 to 16; and / or, b or b i is equal to 1.

10. The hip prosthesis femoral stem system according to any one of claims 1 to 5, characterized in that: The proximal end of the femoral stem is provided with a coating and vertical grooves; and / or, the mid-distal end of the femoral stem is conical; And / or, the entire stem body of the femoral stem is a rectangular double-tapered stem.

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