Diagnosis and Management of Extra-articular Causes of Pain After Total Knee Arthroplasty.

Postoperative pain, which has been attributed to poor outcomes after total knee arthroplasty (TKA), remains problematic for many patients. Although the source of TKA pain can often be delineated, establishing a precise diagnosis can be challenging. It is often classified as intra-articular or extra-articular pain, depending on etiology. After intra-articular causes, such as instability, aseptic loosening, infection, or osteolysis, have been ruled out, extra-articular sources of pain should be considered. Physical examination of the other joints may reveal sources of localized knee pain, including diseases of the spine, hip, foot, and ankle. Additional extra-articular pathologies that have potential to instigate pain after TKA include vascular pathologies, tendinitis, bursitis, and iliotibial band friction syndrome. Patients with medical comorbidities, such as metabolic bone disease and psychological illness, may also experience prolonged postoperative pain. By better understanding the diagnosis and treatment options for extra-articular causes of pain after TKA, orthopaedic surgeons may better treat patients with this potentially debilitating complication.