Osteoarthritis of the temporomandibular joint and increase of the horizontal condylar angle: a longitudinal study

Objective Our previous study of patients with unilateral temporomandibular joint (TMJ) osteoarthritis (OA) showed that the affected joints had greater horizontal condylar angle (HCA) compared with the contralateral unaffected joints. However, it was unclear whether the HCA changes preceded or were the result of OA changes. The aim of this longitudinal study was to investigate the relationship between HCA and OA progression. Study Design In total, 127 patients (with or without TMJ disorders) completed baseline and follow-up examinations (average time to follow-up 7.9 years). Generalized estimating equation models were used to account for correlation of observations within the same patients. Results (1) HCA was greater in OA-affected joints than in unaffected joints ( P  = .04). (2) Increased HCA at follow-up was associated with change in joint status from no OA to OA. ( P  = .001). (3) Baseline HCA value alone did not predict future OA diagnosis. (4) All OA changes in fossa/articular eminence morphology, and some combinations of condylar changes, were associated with a greater HCA. (5) OA diagnosis was associated with pain during maximum opening ( P  = .005) and pain history ( P  = .002). (6) Aging alone was not correlated with increased HCA. Conclusions Clinical progression of OA preceded increases in HCA. HCA alone did not predict OA development.