Intra-operative tracking of the trunk during surgical correction of scoliosis: a feasibility study.

OBJECTIVE The purpose of this study was to evaluate the feasibility of a technique for intra-operative tracking of the trunk during scoliosis surgery. MATERIALS AND METHODS Eleven magnetic sensors placed on specific anatomical landmarks are used to compute 11 geometric indices of the trunk. This technique was assessed on a cohort of 40 subjects (19 normal, 21 scoliotic) using an experimental set-up simulating the position of patients during scoliosis surgery. RESULTS The indices varied less than 2 mm and 1 degrees when breathing (except for chest AP diameter), and less than 1 mm and 1 degrees after transient displacement from the initial positioning of the subjects. No significant changes were observed for most of the indices between two acquisition sessions. Comparison between normal and scoliotic subjects demonstrated that the trunk geometry is more influenced by the positioning of each subject on the operating table than by the magnitude of the spinal deformity. CONCLUSION The proposed technique will allow intra-operative tracking of the trunk and enable the surgeon to optimize the correction of both spinal and trunk deformities. The technique can also be used to evaluate the adequacy of patient positioning on the operating table, and to obtain a complete follow-up of patients in pre-, intra-, and post-surgical conditions.