MR Imaging of Synovial Disorders of the Knee: An Update

Synovial Chondromatosis in a Young Athlete: A Report of a Rare Case

Synovial chondromatosis is a rare and benign disorder that involves the synovial lining of joints, synovial sheaths and bursae. The synovial layer of the joint is affected by a metaplastic process which in turn converts it into cartilagenous tissue. Eventually, it gets dislodged and transformed into a loose body in the large joints. We report the case of a 24-year-old young athlete who presented with complaints of painful movements and restriction of joint movements associated with a growing deformity in the right knee joint. This case report aims to describe a rare synovial pathology that necessitated arthroscopic synovectomy and diagnostic arthroscopy to treat, particularly in younger individuals. The atypical feature, in this case, was metaplastic development from the peripheral joint capsule attached to the surrounding cartilage, which, to the extent that the authors are aware, has only been documented in one instance in the record. Magnetic resonance imaging (MRI) was performed which demonstrated evidence of the joint effusion, synovial hypertrophy and a loose calcific body just anterior of the distal femoral condyle causing pressure over the patellar tendon anteriorly as well as a hyper-dense cyst in the popliteal region. Treatment often requires partial or complete synovectomy with either an arthroscopic or open approach.

Computer-assisted validation of the synovitis score

Histopathological examination of synovial specimens can contribute to the diagnosis of chronic joint diseases. A so-called synovitis score has been introduced as a standardised grading system, based on the semi-quantitative evaluation of the three determining features of chronic synovitis: enlargement of synovial lining, density of synovial stroma and inflammatory infiltrate, giving a score between 0 and 9. The present study examines the reliability of this procedure by comparison with exact measurements using computer-assisted image analysis (CAIA). Seventy-one synovial specimens from patients with osteoarthritis (OA, n=22), psoriatic arthritis (PsA, n=7), rheumatoid arthritis (RA, n=35) and from a control group (Co, n=7) were evaluated using both the synovitis score and CAIA. The measurements were transformed to semi-quantitative values analogous to the synovitis score. The differences between the transformed CAIA scores and the pathologist's scores were 0 or +/-1 in 40 cases, whereas in 31 cases the difference was greater than 1 (correlation coefficient r=0.725). The CAIA scores differed significantly between Co and RA cases (p=0.000) as well as between OA and RA (p=0.000). We conclude that the synovitis score was validated by CAIA and can be regarded a reliable grading system that contributes to the diagnostic procedure of chronic joint inflammation.