Effect of post-trochanteric groove support on stance control associated with the pelvic-lumbar system

Background: Many stroke and neuromuscular patients with paraplegia or severe hemiparesis cannot control trunk balance. Objective: To support the pelvis/hip of paresis patients, a new pelvic/hip support system was developed bearing a convex pressing member placed over the post-trochanteric groove, a cutaneous landmark sited on the lateral portion of the gluteus maximus muscle and indicating the posterior aspect of the greater trochanter. Study design: Preliminary study. Methods: Stance control differences in two paretic patients (Guillain-Barré syndrome and stroke sequelae) with or without post-trochanteric groove support were examined. The contact pressure on the post-trochanteric groove was examined in eight healthy volunteers using an impact force sensor. The pelvic-lumbar movement was also examined using three-dimensional motion analysis, and the gluteus muscles activity was evaluated using surface electromyography. Results: Without post-trochanteric groove support, total three-dimensional displacement of the sacral marker was longer in the paresis patients than in normal controls, while post-trochanteric groove support decreased this distance. Post-trochanteric groove support provided compression pressure on the post-trochanteric groove, and all subjects showed a more upright trunk position, providing more anterior pelvic tilting. Six of eight subjects showed increased lumbar lordosis. Five of eight subjects showed gluteus maximus and/or gluteus medius muscle activation. Conclusion: The mechanisms of post-trochanteric groove support were suggested to be spino-pelvic coordination and gluteal muscle activation. Clinical relevance The post-trochanteric groove is a cutaneous landmark located behind the pelvis/hip joint. Applying pressure to the post-trochanteric groove from behind pushes the trunk to adopt a more upright position, leading to improved stance control. Underlining mechanisms appear to be spino-pelvic coordination and gluteal muscle activation.