Format

Send to

Choose Destination
J Orthop Res. 2012 Nov;30(11):1774-80. doi: 10.1002/jor.22137. Epub 2012 Apr 24.

Muscle excursion does not correlate with increased serial sarcomere number after muscle adaptation to stretched tendon transfer.

Author information

1
Orthopaedic Surgery, University of California and Research Service, VA San Diego Healthcare System, San Diego, CA, USA.

Abstract

Chronic skeletal muscle stretch typically increases serial muscle fiber sarcomere number. Since serial sarcomere number correlates with functional excursion in normal muscle, observed changes in sarcomere number are often extrapolated to their new assumed function. However, this has not been well demonstrated experimentally. Thus, we measured the functional properties of muscles stretched due to tendon transfer surgery. Muscle active and passive length-tension curves were measured 1 week and 4 weeks after surgery, and then each muscle was further examined to determine structural adaptation as well as single fiber and fiber bundle passive mechanical properties. We found a disconnect between the functional and structural muscle properties. Specifically, muscle excursion was significantly lower in the transferred muscle compared to controls, even though serial sarcomere number had increased. Furthermore, maximum tetanic tension was significantly reduced, though the two groups had similar physiological cross sectional areas. Passive tension increased in the transferred muscle, which was deemed to be due to proliferation of extracellular matrix. These data are the first to report that muscle morphological adaptation after chronic stretch does not accurately predict the muscle's functional properties. These data have significant implications for examining muscle physiological properties under surgical interventions.

PMID:
22532301
PMCID:
PMC3407307
DOI:
10.1002/jor.22137
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center