Localization Features of Loose Bodies in Secondary Synovial Chondromatosis of the Knee Joint

Aim: To investigate the relationship of cartilage loss in tibiofemoral and patellofemoral joints with the number, size and location of loose bodies in secondary synovial chondromatosis (SC). Methods: Eighty-eight patients with secondary SC were evaluated retrospectively. The size and location of loose bodies were evaluated by both X-ray and magnetic resonance imaging. The relationship between cartilage lesions and the number, location and size of loose bodies were assessed by Chi-square test and Fisher’s exact test. Results: When the relationship between the presence of loose body and cartilage damage was evaluated, it was observed that 83% of subjects (n=74) had cartilage loss at the tibiofemoral joint, 75% (n=66) on the medial and 9% (n=8) of patients had on the lateral side. It was determined that when the number of loose bodies was ≤5, the mean diameter was 7.3 mm (2-21 mm). It was 12.7 mm (2-30 mm) when the number was >5. The most frequently affected locations were the posterior compartment of the posterior cruciate ligament and the superior compartment of the popliteal fossa, regardless of the degree of cartilage loss. Conclusion: We concluded that the higher the cartilage damage, the higher the number and size of loose bodies. We assume that our study provides insight into further investigations to study new classification system for secondary SC in the knee joint