title: Passive skeletal muscle excursion after tendon rupture correlates with increased collagen content in muscle.
abstract: OBJECTIVE
  This study was designed to measure time-dependent changes in muscle excursion and collagen content after tenotomy, and to analyze the correlation between muscle excursion and collagen content in a rabbit model.
  
  
  METHODS
  Twenty-four rabbits underwent tenotomy of the second extensor digitorum longus (EDL) muscles on the right legs and were randomly assigned to three groups based on the period of time after tenotomy (2, 4, and 6 weeks). The second EDL muscles on left legs were used as controls. At each time after tenotomy, passive muscle excursion and collagen content, determined by hydroxyproline content, were measured bilaterally, and the ratio of each value to the normal one was used.
  
  
  RESULTS
  The mean ratio of muscle excursion after tenotomy to the value of the control decreased in a time-dependent fashion: 92.5% at 2 weeks, 78.6% at 4 weeks, and 55.1% at 6 weeks. The mean ratio of hydroxyproline content in muscle to the value of the control increased in a time-dependent fashion: 119.5% at 2 weeks, 157.3% at 4 weeks, and 166.6% at 6 weeks. There was a significant negative correlation between the ratio of hydroxyproline content in muscle after tenotomy to the control values and the ratio of muscle excursion after tenotomy to the control values (r=-0.602, p=0.002).
  
  
  CONCLUSIONS
  The decrease in muscle excursion seems to correlate with the increase in collagen content in the muscle in a time-dependent fashion following tenotomy.
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Il Hyun
authors.initials: IH
authors.lastname: Koh
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Ho Jung
authors.initials: HJ
authors.lastname: Kang
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Jeon
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jae Han
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea. yrchoi@yuhs.ac.
authors.forename: Yun Rak
authors.initials: YR
authors.lastname: Choi
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism*; D006909:Hydroxyproline / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D011817:Rabbits; D013708:Tendon Injuries / Q000378:metabolism*; D013710:Tendons; D058971:Tenotomy; D013997:Time Factors
chemical_list: D003094:Collagen; D006909:Hydroxyproline
keywords: Tenotomy; collagen content; muscle excursion