Another important consideration of our preliminary study was the appropriateness of the 2D and 3D visualizations in the context of a manual therapy class in the laboratory. Therefore, the 2D and 3D viewing modes were evaluated independently. Our evaluators expressed contrasting needs in this regard. On the one hand, it was felt that the 2D view provided a clearer view of the internal soft tissue, such as the cruciate ligaments of the knee. As a result, the 2D view was the preferred mode for studying joints with complex intra-articular ligaments. On the other hand, our evaluators also expressed the opinion that bone structures without intra-articular tissues but with important reliefs (such as the pelvis, skull, spine, ankle.) were easier to examine with the 3D view mode (volume rendering). Our evaluators reported that the interactive 3D view helped them to construct a correct mental model form of the bones in a natural and intuitive way. This 3D view
easily provided visualizations of anatomical elements from viewpoints not generally shown in conventional textbooks. Our evaluators also remarked that the possibility to examine a 3D reconstruction of the musculoskeletal architecture obtained from an actual living patient (instead of a synthetic 2D drawing) would lead to a more precise evaluation of the pathological situation of the patient and an easier determination of hand locations during the practice class of manual therapy.