Changes in lower extremity 3-dimensional load-bearing axes before and after mobile-bearing total knee arthroplasty

This study evaluated changes in the lower extremity 3-dimensional load-bearing mechanical axes in the anteroposterior and mediolateral directions before and at 3 weeks after mobile-bearing total knee arthroplasty. The effects of the degrees of anteroposterior constraint of the designs on the location of the load-bearing mechanical axis at the knee joint level were also assessed. We evaluated 151 knees from 134 patients with 74 knees receiving meniscal bearing-type and 77 knees receiving rotating platform-type prostheses. In the mediolateral direction, both designs showed significant improvements, whereas in the anteroposterior direction, they revealed no improvements postoperatively and were worsened significantly in meniscal bearing type. Differences in the degree of bone and soft tissue involvement for the correction of alignment may explain the findings.