title: Isoforce: A new outrigger system for static progressive orthotic interventions of the proximal interphalangeal joint with constant force transmission-Results of a biomechanical study.
abstract: METHODS
  Bench research-biomechanical study.
  
  
  BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  Not applicable.
authors: Department of Research and Development, Schulthess Klinik, Zurich, Switzerland.
authors: Marion
authors: M
authors: Marrel
authors: Department of Occupational Therapy, Schulthess Klinik, Zurich, Switzerland.
authors: Ulla
authors: U
authors: Jörn Good
authors: Department of Research and Development, Schulthess Klinik, Zurich, Switzerland.
authors: Miriam
authors: M
authors: Marks
authors: Department of Upper Extremities and Hand Surgery, Schulthess Klinik, Zurich, Switzerland.
authors: Daniel B
authors: DB
authors: Herren
authors: Institute for Biomechanics, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland. Electronic address: jgoldhahn@ethz.ch.
authors: Jörg
authors: J
authors: Goldhahn
mesh_terms: D001696:Biomechanical Phenomena; D004867:Equipment Design / Q000379:methods*; D006801:Humans; D008953:Models, Anatomic; D009989:Orthotic Devices / Q000706:statistics & numerical data*; D016059:Range of Motion, Articular / Q000502:physiology; D052582:Trigger Finger Disorder / Q000534:rehabilitation*
keywords: Biomechanical testing; Contracture; Feasibility; Outrigger; Proximal interphalangeal (PIP) joint; Static progressive orthosis