This study tested if abnormal sagittal knee joint loading patterns after total knee arthroplasty (TKA) were present pre-surgery, and if patterns with higher external knee flexion moments were related to the presence and severity of post-surgery anterior knee pain. Gait analysis and clinical evaluation were performed on 34 patients (41 arthroplasties) both before and 12-18 months after TKA, and on 20 healthy age-matched controls at matched velocities. The majority of knees with abnormal flexor or extensor sagittal knee joint loading patterns post-surgery (18 of 26, 69%) also displayed these patterns pre-surgery. Knee joint loading in the early mid-stance phase of walking prior to surgery was identified by stepwise regression as a significant predictor of the presence (exp(beta) = 2.9 CI: 1.2-6.8, p = 0.017) and severity of post-surgery anterior knee pain (R-2 = 0.314, p = 0.019). Therefore, the frequency and severity of anterior knee pain after TKA can be partially explained by retained pre-surgery gait patterns that had higher external flexion moments in the early mid-stance phase, which place higher forces on the patellofemoral joint. (C) 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.