Background/Purpose: Temporomandibular joint (TMJ) arthritis is a common yet widely under recognized feature of Juvenile Idiopathic Arthritis (JIA).  It is often clinically silent and difficult to diagnose without the use of Magnetic Resonance Imaging (MRI).  The primary objective of this study was to describe the TMJ as seen on ultrasound (US) and determine the ability to detect arthritic changes as a means to develop a rapid, bedside screening tool to aid rheumatologists in the early diagnosis of TMJ arthritis.

Methods: Subjects were recruited from the Children’s Hospital of Wisconsin.  The control group consisted of healthy volunteers presenting to the dermatology clinic for routine care of non-rheumatologic conditions.  The study group was composed of children and adolescents with a prior diagnosis of JIA seen at the rheumatology clinic for ongoing care. US was performed in both clinics by the same pediatric rheumatologist trained in musculoskeletal ultrasonography. Images were reviewed for pathology at a later date by the ultrasonographer and a blinded radiologist. JIA patients had their TMJs examined by their primary rheumatologist with their subtype of JIA, active and previously affected joints, and history of TMJ symptoms blinded to the ultrasonographer.  The dermatology patients had their TMJs examined by the ultrasonographer after the completion of the ultrasound study. All subjects filled out a questionnaire about TMJ symptoms at the completion of the study with the results blinded to the study staff until after ultrasound studies were assessed. 

Results:

Full evaluations were performed on 40 subjects (80 TMJs) including 20 JIA patients and 20 healthy controls.  12 females and 8 males were evaluated in each group with a similar age distribution (range 5-18 years old).  The subset of JIA patients evaluated included 2 oligoarticular-persistent, 3 oligoarticular-extended, 4 polyarticular rheumatoid factor (RF) negative, 5 polyarticular RF positive, 1 systemic onset, 4 enthesitis related, and 1 psoriatic arthritis patient.  10 patients had active arthritis at the time of the study in at least 1 non-TMJ joint.

US revealed a small window of the laterosuperior TMJ.  In JIA TMJs (N=40), abnormalities visible included erosions (30%) or irregularities (18%) of the bony contour of the mandibular condyle, hyperemia (13%), effusion (5%), and prominent synovium (25%). Doppler signal within the TMJ space correlated to symptoms 80% of the time.  6 patients (30%) with TMJ abnormality on US had active arthritis in a peripheral joint.  10 TMJs (25%) were abnormal on US in 8 asymptomatic patients (40%).  12 TMJs (30%) were abnormal on US in 9 patients with normal TMJ physical exams (45%). 

Irregularity in the contour of the condyle was observed in 9 (23%) control TMJs (N=40).  An erosion was noted in 1 TMJ (3%).  Doppler activity was noted on two control studies (5%) on the lateral portion of the condyle.  

Conclusion: Point of care US in the rheumatology clinic has potential use to screen for arthritic changes to the TMJ in JIA patients.  Abnormalities to the condyle contour regularly are seen in JIA patients, some of whom are asymptomatic.  This is also the first study to demonstrate Doppler signal may be an indicator of active TMJ arthritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-temporomandibular-joint-arthritis-with-ultrasound-in-juvenile-idiopathic-arthritis/