In vivo kinetic evaluation of an adhesive capsulitis model in rats

J Shoulder Elbow Surg. 2015 Nov;24(11):1809-16. doi: 10.1016/j.jse.2015.06.015. Epub 2015 Jul 31.

Abstract

Background and hypothesis: 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.

Conclusion: This animal model of adhesive capsulitis rendered lasting effects on in vivo kinematics of the shoulder.

Keywords: Adhesive capsulitis; animal model; biomechanics; contracture; frozen shoulder; rat.

MeSH terms

  • Animals
  • Bursitis / physiopathology*
  • Models, Animal
  • Range of Motion, Articular / physiology
  • Rats, Sprague-Dawley
  • Rotation
  • Torque