This is a retrospective study design with the aim to evaluate the clinical procedures we have used the last 15 years to treat JIA patients with unilateral TMJ arthritis. More specifically, the purpose is to evaluate the mandibular growth in all JIA patients with unilateral TMJ arthritis and an asymmetric mandibular growth pattern treated with non-surgical distraction splint therapy between 1994 and 2010 at the dep. of Orthodontics, Aarhus University, Denmark. The evaluation is based on radiological examinations at the beginning of their non-surgical distraction treatment as well as after the patients have finished their distraction-splint therapy.