الفهرس 
CHAPTER (1): AnatomyOnly 14 pages are availabe for public view
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Abstract
The need for gender-specific knee prosthesis is based on the two assumptions; the first, women have results that are inferior to those of men after TKA, and the second, traditional prosthetic designs have failed to address anatomical differences between genders.
A number of clinical studies have refuted the idea that women have worse outcomes than men when using traditional total knee designs. 3,5, 82,93,159
Indeed, some studies found that women achieve essentially the same results as men, or even better . 93,160,161
A systematic review by Merchant et al. Found no evidence for anatomical differences between men’s and women’s knees that would justify a female-specific design. The average anatomical differences between male and female knees can be explained by the smaller height and size of women on average, not by their gender .93
A recent study showed that the shape of the knee is not only dependent on gender, but also on the morphotype of the patient .119
However, these anatomical differences may be so small that have no clinical effect, which would agree with the findings of the present study.
CHAPTER 10 SUMMARY
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A gender-specific total knee prosthesis has been introduced to match the three notable anatomic differences in the female population: a less prominent anterior condyle, an increased quadriceps angle (Q angle), and a reduced mediolateral:anteroposterior aspect ratio.
A NexGen gender-specific femoral component (Zimmer gender-specific NexGen LPS-Flex ) was designed with a narrow mediolateral dimension for a given anteroposterior dimension to more closely match the aspect ratio in the knees of female patients. The anterior flange of the gender-specific femoral component was modified to include a recessed patellar sulcus and reduced anterior condylar height (to account for a less pronounced anterior condyle in women) and a lateralized patellar sulcus (to accommodate the increased Q angle associated with a wider pelvis).
The purpose of the current prospective, randomized study was to compare early functional results, pain improvement , range of motion improvement , deformity correction , patient satisfaction, femoral component fitting to distal femoral condyles and radiographic results in patients who had received either a gender-specific NexGen LPS-Flex or a standard NexGen posterior cruciate substituting (LPS ) total knee prosthesis .
In the current study, it was found that the early clinical outcomes for the knees with a gender-specific NexGen LPS-Flex prosthesis are similar to those for the knees with a standard NexGen LPS prosthesis.
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In both groups, female patients had improved quality of life in terms of pain improvement , range of motion improvement , walking distance, deformity correction , knee society score , Oxford score , WOMAC score, and function after total knee arthroplasty . Negligible differences in terms of patient satisfaction and preference between the two prostheses were also found in five bilateral cases.
With the gender-specific prosthesis, the anterior condylar height is lowered and the sulcus is recessed to avoid a so-called ‘‘overstuffed’’ patellofemoral joint and to allow increased postoperative knee range of motion. It was found that the mean ranges of motion after total knee arthroplasty are indistinguishable between the two groups.
Another design feature of the gender-specific prosthesis is the trochlear groove angle of the femoral component, which is increased by approximately 3 degrees in order to replicate the distinct Q angle difference, thereby enhancing patellar tracking and reducing the need for lateral retinacular release. In the current study, the patellar tilt angle did not differ significantly between the two groups either preoperatively or postoperatively. No knee in either group had subluxation or dislocation of the patella or needed retinacular release.
Because the gender-specific femoral component is narrower in the mediolateral dimension for a given anteroposterior dimension, use of this implant would have been expected to reduce the prevalence of mediolateral overhanging in comparison with that noted for the female patients with a standard implant.
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Current study results demonstrated that the standard prosthesis fitted the distal part of the femur better than the gender-specific prosthesis . The aspect ratio of the distal part of the femur was closer to that of the standard prosthesis than it was to that of the gender-specific prosthesis.
Prevalence of the risk of overhanging in standard prosthesis was 20 percent with minimal undercoverage with femoral component downsizing not exceeding 3-4 mm . In the gender-specific group prevalence of undercoverage exceeds 70 percent of patients varies from 2 mm to 10 mm .
Undercoverage of distal femur by gender-specific component did not affect early functional results of total knee artyhroplasty . Whether undercoverage of the gender-specific knee prosthesis leads to increased osteolysis resulting from wear debris remains to be seen after longer follow-up.
It was observed that with standard prosthesis in about 20 % of female cases , surgeon either accept mediolateral overhanging with its potential soft tissue irritation and post operative pain or downsize femoral component with its potential over resection of posterior femoral condyles , flexion-extention mismatch and mid flexion instability .
With gender-specific knee , in most cases ( about 70 %) surgeon must accept mediolateral undercoverage ( varying from 2 to 10 millimeters ) when using correct anteroposterior size. Gender-specific prosthesis better restores the quadriceps (Q) angle and better restores size of anterior femoral condyles of female patients which is more prominent in males than females .