Collagenase treatment decreases muscle stiffness in cerebral palsy: A preclinical ex vivo biomechanical analysis of hip adductor muscle fiber bundles
Jason Howard, Venus Joumaa, Karyn G. Robinson, Stephanie Lee, Robert E. Akins, Faizan Syed, M. Wade Shrader, James S. Huntley, H. Kerr Graham, T.R. Leonard, Walter Herzog
Abstract
Abstract Aim To determine the dose–response relationship of collagenase Clostridium histolyticum (CCH) on collagen content and the change in muscle fiber bundle stiffness after ex vivo treatment of adductor longus biopsies with CCH in children with cerebral palsy (CP). Method Biopsy samples of adductor longus from children with CP (classified in Gross Motor Function Classification System levels IV and V) were treated with 0 U/mL, 200 U/mL, 350 U/mL, or 500 U/mL CCH; percentage collagen reduction was measured to determine the dose–response. Peak and steady‐state stresses were determined at 1%, 2.5%, 5%, and 7.5% strain increments; Young's modulus was calculated. Results Eleven patients were enrolled (nine males, two females, mean age at surgery 6 years 5 months; range: 2–16 years). A linear CCH dose–response relationship was determined. Peak and steady‐state stress generation increased linearly at 5.9/2.3mN/mm 2 , 12.4/5.3mN/mm 2 , 22.2/9.7mN/mm 2 , and 33.3/15.5mN/mm 2 at each percentage strain increment respectively. After CCH treatment, peak and steady‐state stress generation decreased to 3.2/1.2mN/mm 2 , 6.5/2.9mN/mm 2 , 12.2/5.7mN/mm 2 , and 15.4/7.7mN/mm 2 respectively ( p < 0.004). Young's modulus decreased from 205 kPa to 100 kPa after CCH ( p = 0.003). Interpretation This preclinical ex vivo study provides proof of concept for the use of collagenase to decrease muscle stiffness in individuals with CP.