Stiff muscle fibers in calf muscles of patients with cerebral palsy lead to high passive muscle stiffness

Margie A. Mathewson, Henry G. Chambers, Paul J. Girard, Mayer Tenenhaus, Alexandra K. Schwartz, Richard L. Lieber*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Cerebral palsy (CP), caused by an injury to the developing brain, can lead to alterations in muscle function. Subsequently, increased muscle stiffness and decreased joint range of motion are often seen in patients with CP. We examined mechanical and biochemical properties of the gastrocnemius and soleus muscles, which are involved in equinus muscle contracture. Passive mechanical testing of single muscle fibers from gastrocnemius and soleus muscle of patients with CP undergoing surgery for equinus deformity showed a significant increase in fiber stiffness (p<0.01). Bundles of fibers that included their surrounding connective tissues showed no stiffness difference (p0.28).). When in vivo sarcomere lengths were measured and fiber and bundle stiffness compared at these lengths, both fibers and bundles of patients with CP were predicted to be much stiffer in vivo compared to typically developing (TD) individuals. Interestingly, differences in fiber and bundle stiffness were not explained by typical biochemical measures such as titin molecular weight (a giant protein thought to impact fiber stiffness) or collagen content (a proxy for extracellular matrix amount). We suggest that the passive mechanical properties of fibers and bundles are thus poorly understood.

Original languageEnglish (US)
Pages (from-to)1667-1674
Number of pages8
JournalJournal of Orthopaedic Research
Volume32
Issue number12
DOIs
StatePublished - Dec 1 2014

Keywords

  • Cerebral palsy
  • Human
  • Mechanics
  • Skeletal muscle

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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