Concave versus posterior-stabilized tibial joint surface in total knee arthroplasty - Randomized evaluation of 47 knees

Forty-seven knees in 43 patients with severe deformities randomly received AMK total knee arthroplasty with concave (C, n = 25) or posterior-stabilize d (PS, n = 22) polyethylene insert and with resection of the posterior cruc iate ligament. Radiostereometric examinations were done postoperatively and after 3, 12. and 24 months. Two patients (1 C, 1 PS) underwent revision su rgery. At the 2-year follow-up, the median absolute rotations of the tibial inserts ranged from 0.13 degrees to 0.26 degrees (C vs PS; P = .1-.7). The maximum total point motion was almost identical in the 2 groups (C, 0.38; PS, 0.39; P = .9). Maximum subsidence, lift-off, and Hospital For Special S urgery scores did not differ (P = .1-.6). Recipients of 20 of 24 knees with concave design and 14 of 19 knees with posterior-stabilized design reporte d that their knee could be regarded as normal or almost normal. Variations of the configuration of the polyethylene insert did nor alter the outcome i n the short term.