The effectiveness of cruciate-retaining versus posterior-stabilized designs on extensor mechanism function and knee function in patients after simultaneous bilateral total knee arthroplasty: A two-year retrospective follow-up study.

Introduction: The importance of the posterior-cruciate ligament in knee functionality is known; however, the effect of preserving the posterior-cruciate ligament in total knee arthroplasty (TKA) on extensor mechanism function and knee function is not clear. We aimed to compare extensor mechanism function and knee function between patients operated with the cruciate-retaining and posterior-stabilized designs for simultaneous bilateral TKA.
Hypothesis: Patients operated with the cruciate-retaining design would produce better outcomes than those operated with the posterior-stabilized design.
Materials and Methods: A total of 104 patients were divided into two groups as the cruciate-retaining (n=52) and posterior-stabilized (n=52) groups. The groups were compared for extensor mechanism function (chair-rise test) and knee function (Hospital for Special Surgery [HSS] knee score). The follow-up points were six weeks, three months, six months, one year and two years.
Results: No statistically significant effect on chair-rise performance of the group-by-time interaction (χ ² [5, n=104]=5.32, p=.37) or of group (χ ² [1, n=104]=1.69, p=.19). In the HSS knee score, the group-by-time interaction was statistically significant (F [5.510]=6.24, p<.001). A statistically significant difference of 7.4 points in favor of the posterior-stabilized group was found at six weeks (p=.002). No statistically significant differences were found between the groups at the other follow-up points.
Discussion: The cruciate-retaining and posterior-stabilized designs have similar outcomes with regard to extensor mechanism function and knee function in the long-term period in patients who underwent simultaneous bilateral TKA. In the short-term period, the posterior-stabilized design shows better knee function than the cruciate-retaining design.
Level of Evidence: III; a retrospective study.
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