A localized injection of corticosteroids into the temporomandibular joints (TMJs) — the joints near the ears where the jawbone connects to the skull — may ease inflammation and help with mouth opening in adolescents with juvenile idiopathic arthritis (JIA) and TMJ swelling, a study suggests.
The study, “Efficacy and safety of intraarticular corticosteroid injections in adolescents with juvenile idiopathic arthritis in the temporomandibular joint: a Norwegian 2-year prospective multicenter pilot study,” was published in the journal Pediatric Rheumatology.
The TMJs are commonly affected in JIA patients, leading to improper joint function, growth impairment, and deformities of the teeth and face.
Between 40% and 90% of JIA patients have arthritis of the TMJs, previous MRI studies have suggested. This variability may be due to the late onset of symptoms in certain patients, posing a challenge to diagnosis.
One of the therapeutic approaches in TMJ arthritis includes intraarticular corticosteroid injections, called IACs. Specifically, clinicians inject corticosteroids directly into the joint to ease inflammation. IACs have been reported to lead to a short-term relief of TMJ pain and maximal incisal opening (MIO), a term used to describe the maximum mouth opening.
However, certain studies suggest that IACs may actually promote mandibular growth impairments and that the easing of TMJ inflammation is highly variable.
As such, further studies, especially those using MRI scans and in which patients are followed over time, are required to understand whether such injections with corticosteroids can be beneficial for people with JIA.
Now, researchers in Norway evaluated the effect of IACs administered to 15 adolescents with active JIA and TMJ arthritis, followed for two years. The participants had a median age of 15 at the study’s start and 80% were girls.
All were taking part in the Norwegian JIA Study (NCT03904459), a five-year observational study assessing oral health and quality of life among children with JIA.
The most common disease subtype was persistent oligoarticular JIA (six patients, 40%) followed by rheumatoid factor-negative polyarticular JIA in five patients (33%).
In total, the participants underwent 22 IACs. Almost all (13 patients) received a single injection, with five participants given an IAC into both (bilateral) TMJs. The two remaining adolescents received repeat injections on one of the TMJs up to 13 months after the first IAC.
Evaluations were done at a median of two, 12, and 22 months after the injections.
The researchers assessed a TMJ pain-index score — a measure of pain frequency and pain intensity, as reported by the patients in the two weeks prior to the evaluations — and maximum mouth opening. Inflammation and bone damage scores also were evaluated according to two MRI scoring systems.
During the two years of follow-up, 10 adolescents (67%) changed or increased their medication with biologics and general disease-modifying anti-rheumatic drugs called DMARDs. Five patients were in disease remission either on or off medication.
TMJ pain-index scores after two months decreased (improved) from a median score of 6.0 to 2.0; however, this reduction was not statistically significant. A minimal, but significant improvement in MIO was found in the same period, from a median of 44 mm to 45 mm.
After two years, scores were lower regarding pain frequency and intensity, jaw function, and pain-index score.
More than half of the evaluated patients (six of 11, 55%) saw an absolute improvement in pain-index after two months. This also was seen in nine of 13 patients (69%) after one year, and in eight of 10 (80%) after two years.
Next, the researchers assessed inflammation and joint damage by MRI scoring, using so-called additive and progressive systems. The additive scores — ranging from zero to eight for inflammation and zero to five for damage, in which higher scores mean worse outcomes — were obtained by accounting for the presence and degree of several joint and bone marrow alterations. In turn, the progressive scoring (ranging from zero to four) was obtained from a single value of inflammation or bone deformity.
The scientists observed that the additive inflammatory scoring was significantly reduced after two months when compared with the start of the study, from a mean score of 4.4 to 3.4. After two years, it dropped to a mean of 2.3.
No significant differences were seen regarding bone damage scores, nor in the progressive scoring for inflammation and bone deformity.
There were no adverse events linked to the corticosteroids injections, and no signs of intra-articular lesions with calcium deposits were found on MRI.
Overall, “we found that a single IAC in combination with systemic [whole-body] therapy may improve short-term and long-term MRI-assessed inflammation and MIO, even though pain and MRI-assessed damage did not improve significantly,” the researchers wrote.
Additional trials are required “to fully elucidate the effect of IACs on TMJ arthritis,” they concluded.