Are There Identifiable Risk Factors Associated With Heterotopic Ossification of the Temporomandibular Joint?

Heterotopic ossification (HO) is defined as bone where it does not belong and as the abnormal presence of calcifications within soft tissues or joints. The purpose of this study was to answer the following clinical question: Are there identifiable risk factors associated with HO in and around the temporomandibular joint (TMJ)?

We designed a retrospective review of patients seen at the Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, between January 1985 and December 2019 and diagnosed with HO involving the TMJ. Variables studied included demographic factors, medical history including hereditary conditions, and specific TMJ history including past interventions. The primary outcome variable was the diagnosis of HO based on radiographic findings using the classification system described by Turlington and Durr. Inclusion criterion was clinical or radiographic evidence of TMJ HO.

A total of 67 patients met the inclusion criteria. There were 48 females and 19 males (2.5:1) with an average age of 44.1 ± 16.7 years (range, 5-76 years). Risk factors associated with TMJ HO included musculoskeletal disease, psychiatric illness, history of trauma or previous TMJ surgeries, and congenital conditions. Of these, a history of nonsurgical TMJ therapy (odds ratio [OR], 3.5; P < .00) was most closely associated with HO. This was followed by male sex (OR, 3.1; P = .001), other craniofacial or musculoskeletal surgeries (OR, 2.4; P = .004), TMJ surgeries (OR, 1.9; P = .012), and neurogenic injury (OR, 1.8; P = .018). The results also demonstrated that patients diagnosed with TMJ HO were medically complex, with 86.6% presenting with other systemic conditions.

This study identifies several risk factors which differ from those reported in the orthopedic literature. The Turlington and Durr classification is only partially helpful in clinical decision-making and needs to include HO associated with TMJ alloplasts and autogenous bone grafts (eg, costochondral grafts).