In this proof-of-concept study, we investigated how orofacial physiotherapy and home-exercise programs affected patients with JIA and TMJ involvement. The findings demonstrated that orofacial pain frequency and intensity significantly decreased throughout the treatment period, with additional reductions observed at the three-month follow-up. During treatment, the mandibular function enhanced significantly as evidenced by improved maximal mouth opening capacity, laterotrusion, and protrusion.

Physiotherapy and therapeutic exercises are currently utilized to reduce facial pain, enhance TMJ function, increase active and passive mouth opening capacity in temporomandibular disorders [3, 12, 14,15,16]. However, little is known about the impact of physiotherapy on JIA-related orofacial manifestations. The 2023 interdisciplinary consensus-based recommendations on the management of orofacial manifestations of JIA propose various orofacial pain management strategies, such as implementing a stabilizing splint, prescribing physiotherapy and/or medication, and informing about further pain-avoidance measures [3, 17]. The combination of splint therapy and physiotherapy is considered a safe and reversible option [3]. However, these recommendations are supported solely by empirical evidence and hence require further investigation [3]. Furthermore, orofacial exercise concerning patients with JIA are not described. The main objective of our proof-of-concept study was to evaluate the effectiveness of orofacial physiotherapy and suggest a home exercise program for patients with JIA and orofacial symptoms.

According to our results, orofacial pain frequency and intensity significantly decreased over the course of the treatment. Tabeian et al. suggested that oral physiotherapy or well-functioning orthodontic splints, which apply pressure on the affected TMJ, reduce the catabolic impact of tumor necrosis factor-alpha (TNF-α) on the TMJ [17, 18]. Also, von Bremen et al. have shown in an experimental model that functional joint loading reduces inflammation and positively affects condylar growth at a histological level [19]. In our study, pain did not recur by three months after active treatment cessation. This sustained effect could be attributed to a change in the inflammatory milieu induced by physiotherapy and/or prescribed home exercises.

Our results indicate that physiotherapy also improves mouth opening capability, laterotrusion, and protrusion. These findings are in line with other studies [20,21,22]. Crepitation and translation did not significantly benefit by physiotherapy in our sample. Although physiotherapy and home exercises seems to improve TMJ dysfunction, this indicates that full TMJ recovery may not be achieved in patients with JIA and TMJ deformity. This is expected if arthritis related structural alterations or degeneration of the TMJ are present. The sustainability of the beneficial effects of therapy also remains unclear, as some rebound tenderness of the masseter and temporalis muscles was observed after treatment cessation, though the pre-treatment level was not reached over our three month follow-up timeline (for masseter).

In our study, the most common physiotherapy interventions were treating soft tissue/stretching for masticatory muscles, strengthening of orofacial muscles, anterior/caudal traction and guided active TMJ mobilization. Shimada et al. found that mobilization therapy including manual therapy and passive jaw mobilization with oral appliances improved TMJ functioning for patients with painful TMJ disorders [23]. The most frequently prescribed home exercises in this study comprised facial muscle relaxation, TMJ mobilization, jaw elevation, depression and lateral deviation, and TMJ relaxation. In Shimada et al.‘s research, voluntary jaw exercises served as a useful complement to physiotherapy in reducing myalgia and arthralgia [23]. Mienna et al. hypothesized that individualized exercises in the rehabilitation process of TMJ dysfunction increase the confidence in patients with chronic TMJ pain [24]. This could explain the high degree of compliance with home exercises. Our results extend existing literature by demonstrating that the positive affects of physiotherapy and high compliance can also be achieved in children and adolescents with JIA and TMJ-involvement.

This study is limited by the small sample size. Also, the follow-up time is relatively short and the potential for additional relapse of the therapy benefits beyond the study timeline cannot be assessed. One patient suffered from a sinus infection at T0, but the main conclusions remain robust after removing this patient from the analysis. As compliance is self-reported, it might be subject to response bias. Additionally, benefical changes in our sample may reflect natural fluctuation of the disease and orofacial symptoms rather than treatment effect. The study did not assess the interference of medication with the treatment. Furthermore, it remains unclear whether the positive outcomes result from physiotherapy or home exercises or can only be obtained through their combination. The strengths of the study are the prospective design, the recommended exercise options and standardized examination form. Further research should apply the implemented treatment plan to a larger sample of patients with longer follow-up periods in randomized controlled set-ups. Furthermore, future studies should investigate how medication changes and systemic inflammation mediate the treatment effect of physiotherapy.