Abstract
Chronic posterior knee pain and swelling in the adolescent athlete generates a broad differential including Baker cyst, ligamentous tear, meniscal injury, popliteus tendonopathy, medial tibial stress syndrome, deep venous thrombosis, chronic exercise induced compartment syndrome, popliteal artery entrapment syndrome, and, in this case, chronic synovitis. One should approach the evaluation of patients with these complaints systematically keeping these diagnoses in mind. A reasonable approach is to begin with plain films and consider higher level imaging such as Doppler ultrasound, magnetic resonance imaging, magnetic resonance arthrography, or bone scan as appropriate based on history and physical. This case illustrates an unusual presentation of chronic knee synovitis. Although various treatments are available for refractory synovitis, arthroscopic synovectomy not only allows for diagnosis, it remains the most well-established procedure for the treatment of this condition. © 2010 American Academy of Physical Medicine and Rehabilitation.