Comparison of a standard and a gender-specific posterior cruciate-substituting high-flexion knee prosthesis: a prospective, randomized, short-term outcome study.
BACKGROUND
Recently, much debate has focused on the effect of gender-specific total knee arthroplasty. The purpose of the present study was to compare clinical and radiographic results as well as femoral component fit in patients receiving either a standard posterior cruciate-substituting LPS-Flex or gender-specific posterior cruciate-substituting LPS-Flex total knee prosthesis.


METHODS
Sequential simultaneous bilateral total knee arthroplasty was performed for eighty-five patients (170 knees). Eighty-five women (mean age, 69.7 years) received a standard LPS-Flex prosthesis in one knee and a gender-specific LPS-Flex prosthesis in the contralateral knee. The mean duration of follow-up was 2.13 years. At each follow-up, the Knee Society score, the Hospital for Special Surgery knee score, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, and radiographs were evaluated. The aspect ratio of the distal part of the femur was compared with those of the standard LPS-Flex prosthesis and the gender-specific LPS-Flex prosthesis.


RESULTS
The mean postoperative Knee Society scores (95.5 points in the standard implant group, compared with 96.5 points in the gender-specific implant group) and Hospital for Special Surgery knee scores (90.7 points in the standard implant group, compared with 91.2 points in the gender-specific implant group) were similar in both groups. The mean postoperative WOMAC score was 36.6 points. Postoperatively, the mean ranges of knee motion in the supine position (125 degrees in the standard implant group, compared with 126 degrees in the gender-specific implant group), patient satisfaction (8.3 points in the standard implant group, compared with 8.1 points in the gender-specific implant group), and radiographic results were similar in both groups. The femoral component in the standard implant group fit significantly better than that in the gender-specific implant group (p < 0.0001).


CONCLUSIONS
The present study did not show any clinical benefits of a gender-specific LPS-Flex total knee prosthesis at the time of short-term follow-up. Longer follow-up is needed to determine whether there will be an advantage in terms of longer-term function.


LEVEL OF EVIDENCE
Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.