Idiopathic scoliosis is a deformity of the spine that affects 2–3% of adolescents. The treatment of scoliosis often requires the use of a rigid brace to align the spine and prevent progression of the deformation. The most common brace, referred to as the Boston brace, has a high success rate in preventing progression of the scoliotic curve. The common root failure is lack of patient compliance in wearing the brace for the prescribed time. This lack in compliance is due to patient discomfort, both physically and emotional, and the patients’ limited ability to perform activities of daily living (ADL) when wearing the brace. The likelihood of needing surgery increases dramatically when bracing is unsuccessful.
We seek to improve patients’ comfort by designing a brace that improves range of motion, while remaining stiff in the corrective direction. Primary ranges of motion were acquired using a motion capture system. A kinematic analysis was performed using homogeneous transformations and screw theory to determine primary screw axes of the motions. The required lateral stiffness for the brace was found in literature.
Compliant mechanisms are used because they can apply the corrective force, but also allow the patients some range of motion. The mechanism implementation was characterized using finite element analysis and compared to a physical model test.
Initial findings confirm that compliant mechanisms are suitable for the application of a scoliosis brace. We have found that the proposed brace can apply the necessary forces at reasonable displacements. The proposed brace will not allow the patient a full range of motion, but we believe that it will achieve an improved range of motion that will increase a patient’s ability to perform activities of daily living.