Factors associated with patient-reported mouth opening activity limitations in individuals with persistent intra-articular temporomandibular disorders: A cross-sectional study exploring physical and self-reported outcomes

Background: Individuals living with intra-articular temporomandibular disorders (IA-TMDs) often report limitations with mouth opening activities. While clinical measures such as active range of motion (AROM) and movement quality are often used to assess mouth opening function, it is unclear if and how these relate to patient-reported limitations and whether other factors such as kinesiophobia influence mouth opening activities in those with IA-TMDs. Objectives: Compare clinical measures of mouth opening function in those with IA-TMDs to asymptomatic controls. In those with an IA/TMD, explore relationships between patient-reported mouth opening limitations, and mouth opening function and kinesiophobia. Design: Cross-sectional study. Method: Clinical mouth opening function (AROM, movement quality, pain on movement/10, stiffness on movement/10) was compared between groups (n = 30 IA-TMD, n = 30 controls). Within the IA-TMD group, correlations between patient-reported mouth opening limitations (Patient specific functional scale), kinesiophobia (Tampa Scale for Kinesiophobia for Temporomandibular Disorders) and clinical measures of mouth opening function were explored. Results: Impairments in AROM (-4 mm, p = 0.04, d = 0.5), movement quality (p < 0.01, phi = 0.6), pain on movement (p < 0.01, d = 0.8) and stiffness on movement (p < 0.01, d = 1.6) were observed in the IA-TMD group compared to controls. Patient-reported mouth opening limitations and kinesiophobia were significantly correlated (r = -0.48, p < 0.01); no correlation was found between patient-reported limitations and clinical mouth opening measures (r < 0.3, p > 0.05). Conclusions: Mouth opening function is impaired in IA-TMD. However, kinesiophobia appears more related to patient-reported mouth opening limitations than clinical impairments. Consideration of clinical, kinesiophobia and patient-reported limitation measures are necessary to direct management of IA-TMD in those presenting for care.