This study was performed to evaluate whether derotation and/or translation are the correct mechanisms of bracing with the Chenau brace in treatment of adolescent idiopathic scoliosis. Bracing in the treatment of adolescent idiopathic scoliosis is an accepted procedure. Variable types of braces with different correction principles are in use. The Boston and the Milwaukee brace correction mechanisms seem to be clear, but not for the Chenau brace which is said to be an inspiration/ derotation device. Curves were measured according to Cobb and rotation of the apex vertebra was determined according to Perdriooe. Translation of the apex vertebra perpendicular to the centre sacral line was measured according to Mason and Carango. Measurements were performed on standing radiographs AP and were taken immediately before starting therapy, six months afterwards to ascertain initial correction, and at least one year after treatment. Compliance was judged as follows: regular and frequent control examinations, an obviously used brace, and visible skin signs. Two groups were formed (Group A: good compliance, n=33, Group B: bad compliance, n=22). In Group A, continuous curve correction of 6° Cobb angle was evident. Patients in Group B showed a mean curve progression of 4° (t=test, p=0.003). After six months of therapy, both groups demonstrated signifi- cant apex translation (Group A: p=0.0001, Group B: p=0.0003). The difference between the groups was not significant, but no significant derotation of the apex vertebrae. At follow-up patients with good compliance showed almost the same apex distance as before therapy, whereas deterioration was evident in Group B (p=0.01). The difference of p=0.04 between the two groups was significant. Apex rotation was significantly increased in both groups (Group A: p=0.02, Group B: p=0.03) and the difference between the two groups was not significant. Curve correction in idiopathic scoliosis with the Chenau brace is a translation process and can be determined as a shift of the apex vertebra to the centre sacral line. Therefore, the Chenau brace is not a derotation device.
