title: In vivo kinetic evaluation of an adhesive capsulitis model in rats.
abstract: OBJECTIVE
  We hypothesized that extra-articular, internal fixation of the shoulder in rats would result in a subsequent decrease in rotational range of motion (ROM) and an increase in joint stiffness. We further hypothesized that residual kinematic changes would still be present at 8 weeks after immobilization. Extra-articular, internal fixation of the shoulder has been used to induce adhesive capsulitis in rats; however, the effects on in vivo kinematics have not been assessed.
  
  
  METHODS
  Baseline measurements of rotational torque and ROM were acquired (n = 10 rats), and the left forelimb of each animal was immobilized with sutures passed between the scapula and the humeral shaft. After 8 weeks, the sutures were removed, and changes in kinematics and kinetics were longitudinally quantified in the follow-up period. Changes in stiffness, defined as the area under the angle-torque curve, were also quantified.
  
  
  RESULTS
  Immediately after suture removal, there was a 63% decrease in total ROM compared with baseline (51° ± 10° vs. 136° ± 0°; P < .001). Similarly, total torque was found to increase 13.4 N.mm compared with baseline (22.6 ± 5.9 N.mm vs. 9.2 ± 2.6 N.mm; P = .002). Residual total ROM restrictions and an increased torque in internal rotation were still evident at 8 weeks of follow-up (113° ± 8° vs. 137° ± 0°, P < .001 and 3.5 ± 0.4 N.mm vs. 2.7 ± 0.7 N.mm, P = .036). Stiffness also increased after suture removal and at 8 weeks of follow-up compared with baseline.
  
  
  CONCLUSIONS
  This animal model of adhesive capsulitis rendered lasting effects on in vivo kinematics of the shoulder.
authors.affiliation: Center for Advanced Orthopaedic Studies, Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Villa-Camacho
authors.affiliation: Center for Advanced Orthopaedic Studies, Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Okajima
authors.affiliation: Center for Advanced Orthopaedic Studies, Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA.
authors.forename: Miguel E
authors.initials: ME
authors.lastname: Perez-Viloria
authors.affiliation: Center for Advanced Orthopaedic Studies, Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA; Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA.
authors.forename: Kempland C
authors.initials: KC
authors.lastname: Walley
authors.affiliation: Department of Anesthesiology, Boston Children's Hospital-Harvard Medical School, Boston, MA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.affiliation: Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA.
authors.forename: Edward K
authors.initials: EK
authors.lastname: Rodriguez
authors.affiliation: Center for Advanced Orthopaedic Studies, Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Center-Harvard Medical School, Boston, MA, USA. Electronic address: anazaria@bidmc.harvard.edu.
authors.forename: Ara
authors.initials: A
authors.lastname: Nazarian
mesh_terms: D000818:Animals; D002062:Bursitis / Q000503:physiopathology*; D023421:Models, Animal; D016059:Range of Motion, Articular / Q000502:physiology; D017207:Rats, Sprague-Dawley; D012399:Rotation; D019415:Torque
keywords: Adhesive capsulitis; animal model; biomechanics; contracture; frozen shoulder; rat