title: Biomechanics of the Steindler flexorplasty surgery: a computer simulation study.
abstract: OBJECTIVE
  Our goal was to investigate the capacity of a Steindler flexorplasty to restore elbow flexion to persons with C5-C6 brachial plexus palsy. In this procedure the origin of the flexor-pronator mass is moved proximally onto the humeral shaft. We examined how the choice of the proximal attachment site for the flexor-pronator mass affects elbow flexion restoration, especially considering possible side effects including limited wrist and forearm motion owing to passive restraint from stretched muscles.
  
  
  METHODS
  A computer model of the upper extremity was used to simulate the biomechanical consequences of various surgical alterations. Unimpaired, preoperative, and postoperative conditions were simulated. Seven possible transfer locations were used to investigate the effects of choice of transfer location.
  
  
  RESULTS
  Each transfer site produced a large increase in elbow flexion strength. Transfer to more proximal attachment sites also produced large increases in passive resistance to wrist extension and forearm supination.
  
  
  CONCLUSIONS
  To reduce detrimental side effects while achieving clinical goals our theoretical analysis suggests a transfer to the distal limit of the traditional transfer region.
authors.affiliation: Biomechanical Engineering Division, Mechanical Engineering Department, Department of Functional Restoration School of Medicine and Bioengineering Department, Stanford University, Stanford, CA, USA.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Saul
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Murray
authors.forename: V R
authors.initials: VR
authors.lastname: Hentz
authors.forename: Scott L
authors.initials: SL
authors.lastname: Delp
mesh_terms: D001696:Biomechanical Phenomena; D020516:Brachial Plexus Neuropathies / Q000503:physiopathology* / Q000601:surgery*; D003198:Computer Simulation; D004551:Elbow Joint / Q000503:physiopathology*; D006801:Humans; D014955:Wrist Joint / Q000503:physiopathology*