FLUOROSCOPIC ANALYSIS OF KINEMATICS AFTER POSTERIOR-CRUCIATE-RETAINING KNEE ARTHROPLASTY

We used fluoroscopy to study the kinematics of the knee in 47 patients with total knee arthroplasty (TKA) and four control subjects with nor mal knees while performing a single-leg deep-knee bend. The videos wer e analysed using still photographs taken at 5 degrees increments of fl exion, Femorotibial contact points, patellar ligament rotation, and pa tellar rotation were calculated from each image. Maximum weight-bearin g flexion was determined for each knee. Compared with the control grou p, posterior-cruciate-retaining TKA did not reproduce normal knee kine matics in any case, but showed a starting point posterior to the tibia l midline which translated anteriorly with flexion. The curves from su ccessive knee bends could not be consistently reproduced. Under weight -bearing conditions, the maximum flexion for any PCR TKA was 98 degree s and several patients could not flex beyond 70 degrees.