Temporomandibular Joint Abnormalities in Hemodialysis Patients: A Cross-Sectional Ultrasonographic Study from a Single Center in Italy

Background/Objectives: Temporomandibular joint (TMJ) abnormalities are a common finding in the general adult population, but they have been rarely investigated in people receiving chronic dialysis. The TMJ is a unique synovial joint that can be altered by either inflammatory or degenerative processes, both of which are amenable to ultrasound (US) assessment. The aim of this study was to describe the pattern of TMJ involvement in a cohort of hemodialysis patients using TMJ ultrasound (TMJ US). Methods: This cross-sectional, single-center study evaluated the clinical utility of TMJ US to detect inflammatory and degenerative changes in patients undergoing chronic hemodialysis and was carried out between June and December 2025. Demographic data, dialysis vintage, the Controlling Nutritional Status (CONUT) score and the Charlson Comorbidity Index (CCI) were collected and related to TMJ US findings and to bone-metabolism biomarkers (calcium, phosphate, parathyroid hormone). Results: 100 hemodialysis patients were included (65 male, 65%; mean age 71.6 ± 13.1 years). Comorbidity and undernutrition were frequent findings (CCI ≥ 4 in 63%; CONUT ≥ 3 in 68%). TMJ US revealed that degenerative indicators were more common than inflammatory ones: calcifications (36%), condylar irregularities (33%) and enthesophytes (25%) were the most prevalent degenerative findings, whereas joint effusion (16%), synovial hypertrophy (15%) and cartilage changes (15%) were the leading inflammatory findings; a positive power Doppler signal was rare (1%). Cortical/condylar irregularity was significantly more prevalent in patients with a dialysis vintage of less than 30 months (43.8% vs. 23.1%, p = 0.034), who also had lower serum calcium levels. No other TMJ US finding showed a significant association with age, sex, comorbidity burden, nutritional status, or bone-metabolism parameters on univariate. Conclusions: TMJ US demonstrated a substantial burden of subclinical degenerative and, to a lesser extent, inflammatory TMJ findings in this cohort of hemodialysis patients; none of these abnormalities were spontaneously reported as symptomatic, and their prevalence was independent of age, dialysis vintage, comorbidity, nutritional status and classical bone-metabolism parameters. These findings cannot be directly attributed to the dialysis/uremic environment rather than to age-related degeneration; they support the concept that the TMJ warrants further investigation as a potentially under-recognized target within the broader systemic metabolic derangement of end-stage kidney disease, and suggest that TMJ US is a feasible, accessible technique for detecting subclinical TMJ involvement in this population, pending confirmation of clinical utility in controlled studies.