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Cases
A Swollen, Painful, and Lumpy Knee
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Background
An otherwise healthy 56-year-old woman presents to the clinic with complaints of progressive knee pain and loss of range of motion (ROM). The symptoms have not improved since they began 2 years ago, and they worsen with activity. Further questioning reveals that the woman noticed "lumps in the back of her knee," which made her seek medical attention. She resides in a remote region, and her past medical history is unremarkable.
On physical examination, the patient has an antalgic gait and a moderately effused right knee with limited active and passive knee flexion and extension. No ligament laxity is observed, and meniscal testing produces pain. Palpation of the knee reveals some mild joint line tenderness and multiple hard, mobile nodules in the popliteal fossa. All other joints are unaffected.
Radiographic examination shows mild-to-moderate arthritic changes of the medial compartment, with multiple loose bodies throughout the joint. What is the diagnosis?
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Scroll
down for Hint and Answer
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***** HINT *****
The synovium of the joint is implicated in the disease process.
***** ANSWER *****
Synovial osteochondromatosis (ie, synovial chondromatosis): Synovial osteochondromatosis is a benign metaplastic tumor of the musculoskeletal system that affects the synovial subintimal layer of joints, tendons, and bursae. The synovial metaplasia leads to the formation of islands of cartilage, which eventually become nodules. These nodules may remain fixed in the synovium or break free, leading to cartilaginous loose bodies. These joint fragments eventually ossify and can then be seen radiographically. Although single joints are typically affected, involvement of multiple joints, tendons, and bursae has been reported.
A patient's presentation and radiographic findings can suggest synovial osteochondromatosis, but the pathologic results are definitive. The condition is benign, although rare cases of malignant transformation have been reported.
Treatment is surgical, with arthroscopic or open removal of loose bodies and/or synovium. Recurrence of the disease is common.
For more information on synovial osteochondromatosis, see the eMedicine article Synovial Osteochondromatosis.
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Author:
Raul A. Kuchinad, BSc, MSc,
Queen's University, School of Medicine, and John Birchard, MD, Assistant Professor, Department of Surgery, Queen's University, Ontario, Canada
Queen's University, Kingston, Ontario, Canada
eMedicine Editor:
Sat Sharma, MD
Associate Professor, University of Manitoba, Department of Medicine, Division of Pulmonary Medicine
Source
http://emedicine.com
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