Towards the definition of a patient-specific rehabilitation program for TKA: A new MRI-based approach for the easy volumetric analysis of thigh muscles

After Total Knee Arthroplasty (TKA), a global post-operative rehabilitation programme is commonly performed. However, this current program is not always adapted to every patient and it could be improved by deeply reinforcing weaker thigh muscles. To do this, a muscle volume estimation coupled with force evaluation is required to therefore adapt the rehabilitation as a specific patient exercise plan. In this paper, we presented an MRI protocol allowing the acquisition of the whole thigh as well as a semi-automated pipeline to segment two main groups of thigh muscles, i.e., the quadriceps femoris and the hamstrings muscles. The pipeline is based on a few crosssections manually labelled and a 3D-spline interpolation using directed graphs corresponding points. The seven muscles of ten thighs (70 muscles in total) were segmented and reconstructed in 3D. To assess this pipeline, three types of metrics (volumetric similarity, surface distance, and classical measures) were employed. Furthermore, the inter-muscle overlapping was calculated as an additional metric. The results showed mean DICE was 99.6% (+/- 0.1), Hausdorff Distance was 4.9 mm (+/- 1.8) and Absolute Volume Difference was 2.97 cm3 (+/- 1.94) in comparison to the manual ground truth. The average overlap was 2.05% (+/- 0.54).