3D Condylar Remodeling in Patients with Early Rheumatoid Arthritis

Method: 37 patients (24 female and 13 male) with early clinical diagnosis of RA were evaluated in a two-year longitudinal follow-up. The individual medication, based on the general clinical and serological status, consisted of methotrexate, salazopyrine, or gold salt injections.  Cone-beam CTs were taken at the first visit after diagnosis (V1), in 1-year follow-up (V2) and in 2-year follow-up (V3). 3D virtual surface models were created for condyle and ramus of each patient using the ITK-SNAP software. All the rami of each side in all time-points were superimposed by means of a surface to surface registration using Geomagic Studio. Then, all the condyles were cropped simultaneously at the condylar neck height. The SPHARM-PDM software computed corresponding point-based models using a parametric boundary description for the Shape analysis.  Sample-based composite shapes of each group were created (V1, V2 and V3 for both left and right condyles). Statistical analysis used a multivariate analysis of covariance, to quantitatively test morphological assessment of structural changes.

Result: Remarkable variability in patterns of bone degeneration and repair were observed. Bone lesions observed at V1 or V2 were healed at V2 or V3; however, additional small areas of bone degeneration were also observed in V2 and/or V3. Only 18.9% of the cases presented > 2mm condylar changes between V1-V2; V1-V3 and V2-V3.  The p-value difference color maps (p<0.05) between sample-based composites at V1, V2 And V3 revealed that no areas in the condyles displayed statistically significant bone remodeling.  

Conclusion: Two-year follow up of TMJ RA patients who underwent systemic treatment indicates that only approximately 1/5 of the patients presented condylar changes greater than 2mm.