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Effect of Postoperative Passive Motion on Rotator Cuff Reconstruction With Acellular Dermal Matrix Grafts in a Rat
Keiji Uezono1, Junji Ide2, Takuya Tokunaga1
1Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
Background:
Although postoperative rehabilitation is critical for rotator cuff tendon-to-bone healing and shoulder function recovery, no standardized protocol has been established.
Hypothesis:
Postoperative immediate passive motion is detrimental to tendon-to-bone remodeling and tendon maturation after rotator cuff acellular dermal matrix (ADM) grafting, although postoperative delayed passive motion does no harm.
Study Design:
Controlled laboratory study.
Methods:
Male Sprague-Dawley rats underwent rotator cuff reconstruction with ADM grafts. Their shoulders were immobilized for 2 weeks thereafter. The rats were assigned to 3 different rehabilitation protocols: (1) immobilization without passive motion (nonpassive motion [N-PM], controls), (2) immobilization with immediate passive motion (I-PM), and (3) immobilization with delayed passive motion (D-PM). Specimens obtained 2, 6, and 12 weeks postoperatively were analyzed histologically, and semiquantitative histomorphological measurements of collagen organization, vascularity, and cellularity were obtained; the area of interest was divided into 2 zones, the midsubstance of the graft and the graft-bone interface. Another set of samples taken at 12 weeks was subjected to biomechanical analysis.
Results:
At 2 weeks, there was no significant difference among the groups in terms of semiquantitative histomorphological measurements of collagen organization, vascularity, and cellularity. At 6 weeks, collagen organization at the insertion site was significantly poorer in I-PM than in N-PM and D-PM rats (P = .0095). At 12 weeks, collagen organization at the insertion site and midsubstance of ADM grafts was also significantly poorer in I-PM rats (P = .0125 and P = .0018, respectively), and ultimate load-to-failure was lower in this group (P = .0043).
Conclusion:
While postoperative immediate passive motion was detrimental to remodeled tendon-to-bone healing and to the tendon maturation of ADM grafts placed in the rotator cuff tendon defects, delayed passive motion did no harm.
Clinical Relevance:
For patients with 6-week immobilization after rotator cuff reconstruction, we recommend that early passive motion be started no sooner than 3 weeks after surgery. Immediate early passive motion should be avoided.
