Is Handheld Ultrasonography Reliable as a Primary Imaging Modality for the Diagnosis of Internal Derangement and Degenerative Joint Disease of the Temporomandibular Joint?

Background: Magnetic resonance imaging (MRI) is the gold standard imaging modality for diagnosing internal derangement (ID) and degenerative joint disease (DJD) of the temporomandibular joint (TMJ). MRI disadvantages include cost, availability, and patient discomfort, making it worthwhile to determine if handheld ultrasonography (HHU) may reduce MRI utilization.

Purpose: The purpose of this study was to measure and compare the diagnostic accuracy of HHU to the MRI gold standard for the diagnosis of ID and DJD.

Study design: This retrospective, cohort, single-institutional study included participants with suspected ID and DJD referred by dentists and primary care physicians to the Oral and Maxillofacial Surgery Clinic at the Health Sciences Centre in Winnipeg, Manitoba.

Predictor variable: The predictor variable was the HHU diagnosis of the TMJ for the presence or absence of anterior disc displacement (ADD) and DJD.

Outcome variable: The outcome variable was the MRI diagnosis of the TMJ for the presence or absence of ADD and DJD.

Covariates: Covariates include demographics, medical history, and assessments of ID and DJD based on clinical examination.

Analyses: The diagnostic accuracy of HHU relative to MRI was determined using appropriate statistical tests with a significance level (P value) of ≤0.05 and a 95% CI.

Results: The sample consisted of 20 subjects (mean age: 47 years, SD 13; 17 female, 85%), who were scanned using HHU and MRI. MRI was the comparative standard, and when detecting ADD without reduction, HHU demonstrated specificity of 100.00%, PPV of 100.00%, and a kappa value of .93. For ADD with reduction, HHU demonstrated specificity of 100.00%, PPV of 100.00%, and a kappa value of .79. For DJD, HHU demonstrated specificity of 89.5%, PPV of 20%, and a kappa value of .23.

Conclusion: HHU demonstrated statistically significant specificity and PPV when assessing ID and shows promise as a screening tool for MRI referrals, helping to identify patients who can be maintained on conservative treatment. The diagnostic ability of HHU for the detection of DJD was not statistically significant.