Synovial chondromatosis (SC) is a rare proliferative disorder of synovium characterized by the formation of cartilaginous nodules, which may detach and form intra-articular loose bodies. While most frequently observed in large joints such as the knee and hip, involvement of the temporomandibular joint (TMJ) is uncommon, with only a few hundred cases reported worldwide [1]. Clinically, TMJ SC presents with nonspecific symptoms such as pain, swelling, limitation of mouth opening, joint noises, or deviation on opening, leading to frequent misdiagnosis as temporomandibular disorders (TMD) [2]. As a result, patients often experience delayed diagnosis and treatment, which may result in advanced degenerative changes [3]. Radiologic imaging has transformed diagnosis. CT and CBCT can reveal calcified loose bodies, joint space widening, and bone erosion, while MRI identifies non-calcified nodules, synovial proliferation, and joint effusion [4]. Distinguishing SC from other TMJ pathologies, including degenerative joint disease and chondrosarcoma, is crucial because management strategies differ [5]. Several retrospective studies have recently expanded understanding of TMJ SC. They confirm a predilection for the superior joint space, predominance of glenoid fossa changes compared to condyle, and characteristic calcification patterns such as ring-and-arc or popcorn-like [6,7]. Importantly, severity of degeneration correlates with symptom duration and histopathologic stage [8]. Given the rarity of the condition, most reports are case-based or small series. The present study provides a retrospective review of clinical and imaging features in TMJ SC, highlighting correlations with disease progression and strengthening diagnostic criteria [9,10].

This retrospective study reviewed records of 38 patients diagnosed with TMJ synovial chondromatosis over a 24-year period. Ethical approval was obtained from the Institutional Review Board. Study Population Inclusion criteria were patients with histopathologically confirmed TMJ SC and complete clinical and imaging records. Exclusion criteria included prior TMJ surgery unrelated to SC, incomplete records, or systemic diseases causing similar TMJ pathology. Data Collection Clinical data extracted included age, gender, presenting symptoms (pain, swelling, joint noises, limitation of mouth opening, deviation), and duration of symptoms. Imaging modalities analyzed were CT, MRI, and CBCT. Features assessed included: • Lesion epicentre (superior vs. inferior joint space) • Osseous changes (erosion, sclerosis) in mandibular condyle and glenoid fossa • Calcification patterns (stippled, flocculent, ring-and-arc, popcorn) • Joint space widening • Lesion dimensions in axial, sagittal, and coronal planes Statistical Analysis Data were tabulated in Microsoft Excel and analyzed using SPSS v25. Descriptive statistics summarized clinical and imaging findings. Correlations between symptom duration, calcification type, lesion extent, and severity of osseous degeneration were assessed using Pearson’s correlation and chi-square tests. A p- value <0.05 was considered significant.

Clinical Features The most frequent presenting symptom was pain (78.9%), followed by limited mouth opening (65.7%), swelling (57.8%), joint sounds (47.3%), and deviation on opening (39.4%). Mean symptom duration was 28 months (range: 6–84). A female predominance was observed, with mean age 46.7 years. Table 1. Clinical presentation of TMJ synovial chondromatosis (n=38) Clinical feature n (%) Pain 30 (78.9) Limited mouth opening 25 (65.7) Swelling 22 (57.8) Joint sounds 18 (47.3) Deviation on opening 15 (39.4) Imaging Findings Lesion Epicentre: 34 of 38 patients (89.5%) had lesions confined to the superior joint space. Bone Changes: Glenoid fossa showed more severe erosion and sclerosis compared to condyle. Table 2. Bone changes observed on imaging Site No destruction n (%) Mild (≤50%) n (%) Severe (>50%) n (%) Condyle 16 (42.1) 19 (50.0) 3 (7.9) Glenoid fossa 8 (21.1) 19 (50.0) 11 (28.9) Calcifications: Present in 81.6% of cases, with ring-and-arc and popcorn being most frequent. Table 3. Calcification patterns in TMJ SC (n=31 with calcification) Pattern n (%) Stippled 2 (6.5) Flocculent 4 (12.9) Ring-and-arc 9 (29.0) Popcorn 16 (51.6) Joint Space Widening: Mean affected joint space was 6.4 ± 1.2 mm vs contralateral 3.2 ± 0.8 mm. Lesion Size: Average lesion diameter was 18.4 mm (range: 8–35 mm). Table 4. Quantitative imaging parameters Parameter Affected side (mean ± SD) Contralateral side (mean ± SD) Joint space (mm) 6.4 ± 1.2 3.2 ± 0.8 Lesion diameter (mm) 18.4 (range 8–35) –

The present study reinforces established observations about TMJ SC while adding insights into clinical–imaging correlations. Clinically, TMJ SC presents with pain, restricted opening, swelling, and joint sounds, findings that overlap significantly with TMD. This nonspecificity contributes to diagnostic delays, with average symptom duration exceeding two years in many reports [1,2]. Similar to prior studies, we found a female predominance and middle-aged onset, suggesting possible hormonal or mechanical influences [3]. Radiologically, the superior joint space was the most common epicentre, a finding consistent with previous retrospective series [4]. This may be due to greater synovial proliferation and spatial capacity in the superior compartment. Recognition of this predilection can guide clinicians in targeting imaging and differential diagnoses [5]. Degenerative bone changes were more severe in the glenoid fossa and articular eminence than in the condyle, confirming prior observations [6]. This directional damage suggests that proliferating nodules exert greater mechanical stress against the fossa. The presence of ring-and-arc or popcorn calcifications is particularly diagnostic, distinguishing SC from degenerative arthritis or synovial chondrosarcoma [7]. Correlation analysis showed that longer symptom duration and advanced histopathologic stage predicted greater osseous degeneration, consistent with progressive disease [8]. Furthermore, calcification type (ring-and-arc, popcorn) associated with higher degeneration severity, suggesting that calcified bodies contribute more to joint wear [9]. These insights are valuable for staging, prognosis, and surgical planning. From a diagnostic standpoint, distinguishing SC from malignancy is critical. Unlike chondrosarcoma, SC rarely demonstrates infiltrative bone destruction, periosteal reaction, or extra-articular extension. Scoring systems incorporating lesion location, calcification, and bone changes achieve diagnostic accuracies >95%, highlighting the potential of imaging-based decision support [10-15]. Thus, a combination of clinical suspicion, radiographic recognition of hallmark features, and correlation with symptom duration is key for accurate and timely diagnosis of TMJ SC.

Temporomandibular joint synovial chondromatosis is a rare benign disorder that often mimics common TMJ conditions, delaying diagnosis. Clinical features include pain, swelling, restricted opening, and joint noises. Imaging provides essential clues: epicentre in the superior joint space, glenoid fossa degeneration, and characteristic calcification patterns. Severity of degeneration correlates with duration of symptoms, lesion extent, and histopathologic stage. Awareness of these clinical–radiographic correlations is crucial for early recognition, differentiation from malignancies, and appropriate surgical management.

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