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Introduction

Limited postoperative range of motion (ROM) after total knee arthroplasty (TKA) occurs in approximately 1% to 10% of patients. This problem, although associated with pain in many patients, is defined by restricted flexion on physical examination. It should be distinguished from the subjective complaint of stiffness, which may be associated with a normal ROM in some cases. Although the objective measurements that define limited postoperative ROM have not been rigidly defined, published criteria usually specify failure to achieve 75 to 95 degrees of flexion within 6 to 12 weeks after surgery.

Limited postoperative motion may have multiple causes, including arthrofibrosis; an abnormal periarticular fibroblastic response to injury ; technical errors such as component malrotation, overstuffing of the patellofemoral joint, or failure to balance the posterior cruciate ligament in a cruciate-retaining (CR) prosthesis; and inadequate postoperative rehabilitation. Patient risk factors that may contribute to limited postoperative ROM include limited preoperative ROM, obesity; younger age; female gender; and poor postoperative pain control.

Nonsurgical treatment options include physical therapy; continuous passive motion (CPM) machines; active splints; and optimization of pain management; but reported gains in the ROM with these interventions have been inconsistent. Surgical options include MUA, arthroscopic lysis of adhesions and manipulation; open arthrolysis with or without polyethylene exchange; and component revision. Factors that should be considered when selecting optimal treatment include the magnitude of the restriction in motion; time from surgery; technical errors in prosthesis positioning and sizing; type of prosthesis (e.g., CR versus posterior stabilized); and patient factors that cannot be modified, including significant preoperative restrictions in ROM and morbid obesity.

Indications and Contraindications

MUA may be considered for patients with motion limited to less than about 90 degrees of flexion after TKA. Although several authors have reported goods results for MUA performed 90 days after TKA, we prefer to perform MUA between 6 and 12 weeks postoperatively. Before MUA, a comprehensive evaluation should be performed to identify cases for which manipulation is appropriate. Components should be appropriately sized and in acceptable alignment on anteroposterior, lateral, and patella radiographs. A computed tomographic (CT) scan should be obtained if concerns exist about gross component malrotation. Infection, wound problems, and instability should be excluded. Although some authors have demonstrated small improvements with manipulation for persistent flexion contractures, loss of more than 10 degrees of passive full extension is a relative contraindication for MUA. Any attempt at improving passive extension by MUA should be performed cautiously because of concerns about causing a supracondylar fracture. The presence of a functional extensor mechanism without significant lag should be documented before manipulation.

For patients beyond 6 months from surgery, especially with a CR prosthesis, arthroscopic débridement with manipulation or open arthrolysis should be considered. In these cases, if the posterior cruciate ligament is present, release or recession may be performed arthroscopically or during the open débridement.

For unacceptable component positioning or sizing documented by radiographs or CT scans and for patients with significant flexion contractures (>10 degrees), knee revision should be considered. In these cases, femoral, tibial, and patellar revision may be necessary, depending on the problem identified after comprehensive evaluation.