ABSTRACT
STUDY DESIGN: Bench research-biomechanical study. INTRODUCTION: Static progressive orthotic devices are efficient in treating contractures. However, current outriggers are unable to keep force transmission and the force application angle (FAA) constant. PURPOSE OF THE STUDY: To evaluate the biomechanical performance of the Isoforce outrigger, a novel extension orthosis. METHODS: A hand model was used to measure the required force at the outrigger and FAA, while simulating resolution of different contracture angles. We also tested feasibility in a small patient series. RESULTS: The force required with the Isoforce device never exceeded 2.4 N, and the FAA did not change more than 6°. Corresponding figures for the reference devices exceeded 16 N and 20°. The 7 patients testing the Isoforce extension device showed an extension deficit that decreased from 40° at baseline to 25° at 6 weeks. They rated the device as very comfortable to wear. CONCLUSIONS: Isoforce maintains constant force transmission and FAA throughout the full range of motion, promotes the lengthening of contracted structures, and is comfortable to wear. LEVEL OF EVIDENCE: Not applicable.
