Synovial Chondromatosis-Induced Monoarticular Knee Arthritis: Challenges With Arthroscopic Synovectomy on Late Presentation.

Unilateral painful swelling of the knee is one of the most common orthopedic presentations. Monoarticular synovitis of the knee may be present due to inflammation, trauma, age-related degeneration, or tumor pathology. Primary synovial chondromatosis (PSC) is an uncommon cause. A 40-year-old female presented with painful swelling of her left knee for around nine months. She had a flexion deformity of her left knee with minimal hydrops. The radiograph showed speckled calcifications and osteopenia with a reduction of medial joint space. MRI imaging confirmed synovitis with calcifications. She underwent an arthroscopic synovectomy for her management. Her biopsy was consistent with synovial chondromatosis. The initial progression was favorable to allowing independent, unsupported, pain-free activities of daily routine. At three months, however, there was disease progression, causing limitation of knee movements and the need for a walker for support. An uncommon cause of synovitis presents at a late stage with a delay in the early diagnosis and early recognition. PSC is considered a benign lesion with good functional outcomes after arthroscopic surgery. Recurrence and poor functional outcome possibly suggest aggressive disease. A delayed diagnosis and late presentation may be susceptible to recurrence and poor functional outcome, even after an adequate arthroscopic debridement and rigorous post-operative rehabilitation program.