['Septic arthritis of the temporomandibular joint (TMJ) is a rare condition known to result in significant morbidity if diagnosis is delayed. Acute otomastoiditis is a typical complication of acute otitis media but few cases of acute otomastoiditis complicated with TMJ arthritis have been reported in the international literature. Furthermore, otomastoiditis reports and studies rarely analyzed TMJ CT scans. The aim of this study was to determine the incidence of TMJ arthritis in acute otomastoiditis, based on the analysis of CT scans.', 'We conducted a prospective study from 2014 to 2015, including all consecutive pediatric patients admitted to the Pediatric Otolaryngology department for acute otomastoiditis. A craniofacial injected CT scan was performed in all patients. The imagery was prospectively blind analyzed by two independent investigators screening for the criteria of TMJ arthritis. Finally, during the long-term follow-up we noted the number of patients presenting a clinical TMJ ankylosis.', 'We included 45 patients. The analysis showed 15 patients with TMJ effusion. Of those, 6 (13.33%) had an abscess and 2 clinical ankyloses.'] Is tMJ arthritis a frequent complication of otomastoiditis?