Thirty-three patients were evaluated after patellectomy for subjective complaints, objective physical findings, quadriceps strength, and knee motion during activities of daily living. Partial and complete patellectomy caused an equal loss of active and passive range of motion. Complete patellectomy resulted in greater ligament instability, quadriceps atrophy, and loss of quadriceps strength compared with partial patellectomy. Complete patellectomy casued a reduction in the degree of stance-phase flexion during level walking and negotiating stairs.