title: Architectural and biochemical adaptations in skeletal muscle and bone following rotator cuff injury in a rat model.
abstract: BACKGROUND
  Injury to the rotator cuff can cause irreversible changes to the structure and function of the associated muscles and bones. The temporal progression and pathomechanisms associated with these adaptations are unclear. The purpose of this study was to investigate the time course of structural muscle and osseous changes in a rat model of a massive rotator cuff tear.
  
  
  METHODS
  Supraspinatus and infraspinatus muscle architecture and biochemistry and humeral and scapular morphological parameters were measured three days, eight weeks, and sixteen weeks after dual tenotomy with and without chemical paralysis via botulinum toxin A (BTX).
  
  
  RESULTS
  Muscle mass and physiological cross-sectional area increased over time in the age-matched control animals, decreased over time in the tenotomy+BTX group, and remained nearly the same in the tenotomy-alone group. Tenotomy+BTX led to increased extracellular collagen in the muscle. Changes in scapular bone morphology were observed in both experimental groups, consistent with reductions in load transmission across the joint.
  
  
  CONCLUSIONS
  These data suggest that tenotomy alone interferes with normal age-related muscle growth. The addition of chemical paralysis yielded profound structural changes to the muscle and bone, potentially leading to impaired muscle function, increased muscle stiffness, and decreased bone strength.
  
  
  CONCLUSIONS
  Structural musculoskeletal changes occur after tendon injury, and these changes are severely exacerbated with the addition of neuromuscular compromise.
authors.affiliation: Departments of Bioengineering (E.J.S., A.E.R.-S., and S.R.W.), Radiology (S.R.W.), and Orthopaedic Surgery (A.J.C., E.L., A.D.C., and S.R.W.), University of California San Diego, 9500 Gilman Drive (0610), La Jolla, CA 92093. E-mail address for S.R. Ward: srward@ucsd.edu.
authors.forename: Eugene J
authors.initials: EJ
authors.lastname: Sato
authors.affiliation: Department of Orthopaedic Surgery, Washington University, 660 South Euclid Avenue, St. Louis, MO 63110. E-mail address for L.M. Galatz: galatzl@wudosis.wustl.edu.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Killian
authors.affiliation: Departments of Bioengineering (E.J.S., A.E.R.-S., and S.R.W.), Radiology (S.R.W.), and Orthopaedic Surgery (A.J.C., E.L., A.D.C., and S.R.W.), University of California San Diego, 9500 Gilman Drive (0610), La Jolla, CA 92093. E-mail address for S.R. Ward: srward@ucsd.edu.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Choi
authors.affiliation: Departments of Bioengineering (E.J.S., A.E.R.-S., and S.R.W.), Radiology (S.R.W.), and Orthopaedic Surgery (A.J.C., E.L., A.D.C., and S.R.W.), University of California San Diego, 9500 Gilman Drive (0610), La Jolla, CA 92093. E-mail address for S.R. Ward: srward@ucsd.edu.
authors.forename: Evie
authors.initials: E
authors.lastname: Lin
authors.affiliation: Departments of Bioengineering (E.J.S., A.E.R.-S., and S.R.W.), Radiology (S.R.W.), and Orthopaedic Surgery (A.J.C., E.L., A.D.C., and S.R.W.), University of California San Diego, 9500 Gilman Drive (0610), La Jolla, CA 92093. E-mail address for S.R. Ward: srward@ucsd.edu.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Choo
authors.affiliation: Departments of Bioengineering (E.J.S., A.E.R.-S., and S.R.W.), Radiology (S.R.W.), and Orthopaedic Surgery (A.J.C., E.L., A.D.C., and S.R.W.), University of California San Diego, 9500 Gilman Drive (0610), La Jolla, CA 92093. E-mail address for S.R. Ward: srward@ucsd.edu.
authors.forename: Ana E
authors.initials: AE
authors.lastname: Rodriguez-Soto
authors.affiliation: Department of Orthopaedic Surgery, Washington University, 660 South Euclid Avenue, St. Louis, MO 63110. E-mail address for L.M. Galatz: galatzl@wudosis.wustl.edu.
authors.forename: Chanteak T
authors.initials: CT
authors.lastname: Lim
authors.affiliation: Department of Orthopaedic Surgery, Washington University, 660 South Euclid Avenue, St. Louis, MO 63110. E-mail address for L.M. Galatz: galatzl@wudosis.wustl.edu.
authors.forename: Stavros
authors.initials: S
authors.lastname: Thomopoulos
authors.affiliation: Department of Orthopaedic Surgery, Washington University, 660 South Euclid Avenue, St. Louis, MO 63110. E-mail address for L.M. Galatz: galatzl@wudosis.wustl.edu.
authors.forename: Leesa M
authors.initials: LM
authors.lastname: Galatz
authors.affiliation: Departments of Bioengineering (E.J.S., A.E.R.-S., and S.R.W.), Radiology (S.R.W.), and Orthopaedic Surgery (A.J.C., E.L., A.D.C., and S.R.W.), University of California San Diego, 9500 Gilman Drive (0610), La Jolla, CA 92093. E-mail address for S.R. Ward: srward@ucsd.edu.
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Ward
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism* / Q000473:pathology*; D004195:Disease Models, Animal; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology*; D017207:Rats, Sprague-Dawley; D000070636:Rotator Cuff Injuries; D013708:Tendon Injuries / Q000378:metabolism*
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