Patellofemoral knee pain in an adult with radiographic osteoarthritis and human immunodeficiency virus infection.

STUDY DESIGN: Resident's case problem.

BACKGROUND: Kaposi's sarcoma (KS) is the most common form of cancer in patients with human immunodeficiency virus (HIV) infection. Although KS is often initially asymptomatic, this neoplasm may progress to affect multiple organ systems, including structures of the musculoskeletal system, which can produce symptoms similar to those associated with common orthopaedic conditions. This resident's case problem describes the evaluation and differential diagnosis of a 45-year-old male with HIV and KS, referred to physical therapy with an initial diagnosis of radiographic osteoarthritis (OA) and patellofemoral pain syndrome (PFPS) of the left knee. His primary complaint was knee pain during end range knee flexion.

DIAGNOSIS: The history, systems review, and examination suggested a source of pain of a nonorthopaedic origin. Differential examination ruled out clinical OA, PFPS, ligament/cartilage derangement, and tendonitis. Avascular necrosis of the medial femoral condyle was also considered as a possible source of pain. Recent blood tests indicated a high viral load and low CD4 count, which might have increased susceptibility to opportunistic infections or KS tumor progression. The patient was referred back to his physician for additional follow-up. Magnetic resonance imaging (MRI) of the knees were consistent with a systemic inflammatory process such as KS. A true-cut biopsy was subsequently scheduled, which confirmed KS lesions at the left knee.

DISCUSSION: Physical therapists who manage orthopaedic conditions should be aware of the disablement that may result from acquired immunodeficiency syndrome-related KS. A thorough joint-specific examination, with a broad differential diagnosis, should be employed for patients having known systemic diseases.

LEVEL OF EVIDENCE: Differential diagnosis, level 4.