Inclusion Criteria:  Undergone a unilateral primary Total Knee Arthroplasty (TKA) for end-stage osteoarthritis Knee stiffness in the first 6 weeks post-operative defined as knee flexion < 100 degrees  Exclusion Criteria:  Preoperative knee range of motion less than 15-110 degrees Intraoperative (closed) range of motion < 0-120 degrees Radiographic signs of heterotopic ossification Misaligned components or component-related failures of knee prosthesis that could be responsible for difficulties with motion Signs and symptoms consistent with joint infection Signs and symptoms consistent with complex regional pain syndrome