Biomechanical properties of the brachioradialis muscle: Implications for surgical tendon transfer

Richard L. Lieber*, Wendy M. Murray, Dina L. Clark, Vincent R. Hentz, Jan Fridén

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Purpose: To understand the mechanical properties of the brachioradialis (BR) muscle and to use this information to simulate a BR-to-flexor pollicis longus (FPL) tendon transfer for restoration of lateral pinch. Methods: The BR mechanical properties were measured intraoperatively. Passive elastic properties were measured by elongating BR muscles at constant velocity while they were attached directly to a dual-mode servomotor. Sarcomere length was measured intraoperatively and in situ by laser diffraction with the elbow fully extended. Then both the mechanical and structural properties were programmed into a surgical simulator to test the hand surgeon's decision making when tensioning muscles in a simulated BR-to-FPL tendon transfer. Results: Passive mechanical BR properties were highly nonlinear. Under slack conditions sarcomere length (mean ± standard deviation) was 2.81 ± 0.10 μm (n = 4), corresponding to an active force of 93% maximum. Sarcomere length of the BR measured in situ with the elbow fully extended and the forearm in neutral rotation was 3.90 ± 0.27 μm (n = 8), corresponding to an active force of only 23% maximum. Surgeons, who tensioned the BR for transfer into the FPL using only tactile feedback from the surgical simulator, attached the muscle at a passive tension of 5.87 ± 0.97 N, which corresponded to a sarcomere length of 3.84 μm and an active muscle force of 27% maximum. Passive BR tension when both tactile and visual information were provided to the surgeon was significantly lower (2.42 ± 0.72 N), corresponding to a sarcomere length of 3.56 μm and a much higher active muscle force of 45% maximum. Conclusions: When these data were used to model pretransfer and posttransfer function dramatic differences in predicted function were obtained depending on the tensioning protocol chosen. This emphasizes the point that the decision-making process used during muscle tensioning has a profound effect on the functional outcome of the transfer.

Original languageEnglish (US)
Pages (from-to)273-282
Number of pages10
JournalJournal of Hand Surgery
Volume30
Issue number2
DOIs
StatePublished - Mar 2005

Keywords

  • Hand surgery
  • Modeling
  • Sarcomere length
  • Surgical simulation
  • Tendon transfer

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

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