Purpose: The purpose of this investigation is to document quantitatively and qualitatively
the changes that occur over time in the rotator cuff muscle after surgical detachment,
simulating a chronic, unrepaired rotator cuff tear. Methods: The supraspinatus muscle was unilaterally detached from the greater tuberosity in
20 New Zealand white rabbits. All tendons were tagged and retracted from the insertion
on the greater tuberosity. Five rabbits were killed at each designated time interval
of 6 weeks, 3 months, 6 months, or 1 year after surgery. All animals underwent whole-body
perfusion at the time of death for tissue preservation. Gross and histologic evaluations
were performed to quantify the progression of fatty infiltration over time. Results: Loss of muscle and fatty infiltration were evident 6 weeks after detachment of the
supraspinatus tendon. The fatty infiltration increased over time from 6 weeks to 1
year (P = .002, analysis of variance). The fatty infiltration was most pronounced near the
supraspinatus insertion, and it progressed from the musculotendinous junction toward
the muscle origin (Pearson correlation, r = −0.51; P < .0001). Conclusions: In this rabbit model of a surgically created rotator cuff tear, fatty infiltration
is a progressive, infiltrative process that increases over time in the unrepaired
rotator cuff. In addition, the muscle atrophy and fatty infiltration seen in rotator
cuff tears progress from the musculotendinous junction toward the muscle origin. Clinical Relevance: This animal model of a chronic rotator cuff tear shows that fatty infiltration of
the supraspinatus muscle appears as early as 6 weeks and worsens over time in the
unrepaired rotator cuff. This may have implications on both the timing and management
of rotator cuff tears.
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References
- General reactions of muscle to injury. Churchill Livingstone, New York1984
- Biomechanical changes of muscle in rotator cuff rupture. Vol 1. Elsevier, Paris1997
- Chronic rotator cuff injury and repair model in sheep.J Bone Joint Surg Am. 2003; 85: 2391-2402
- Structure and function of the rabbit’s supraspinatus muscle after resection of its tendon.Acta Orthop Scand. 1989; 60: 461-463
- Function of the rabbit supraspinatus muscle after large detachment of its tendon: 6-week, 3-month, and 6-month observation.J Shoulder Elbow Surg. 2000; 9: 211-216
- Alterations in the supraspinatus muscle belly with rotator cuff tearing: Evaluation with magnetic resonance imaging.J Shoulder Elbow Surg. 1994; 3: 88-93
- Fatty muscle degeneration in cuff ruptures.Clin Orthop Relat Res. 1994; : 78-83
- Delayed tendon reattachment does not reverse atrophy and fat accumulation of the supraspinatus—An experimental study in rabbits.J Orthop Res. 2002; 20: 357-363
- Prediction of rotator cuff repair results by magnetic resonance imaging.Clin Orthop Relat Res. 1997; 344: 275-283
- Atrophy of the rotator cuff muscles and site of cuff tears.Acta Orthop Scand. 2002; 73: 40-43
- A pathomechanical concept explains muscle loss and fatty muscular changes following surgical tendon release.J Orthop Res. 2004; 22: 1004-1007
- Practical fixation techniques for light and electron microscopy.Comparative Pathology Bulletin. 1977; 9
- Morphology of the torn rotator cuff.J Anat. 1995; 186: 429-434
- Postoperative assessment of shoulder function: A prospective study of full-thickness rotator cuff tears.J Shoulder Elbow Surg. 1996; 5: 449-457
- The rotator crescent and rotator cable: An anatomic description of the shoulder’s “suspension bridge.”.Arthroscopy. 1993; 9: 611-616
Article info
Footnotes
Supported by a Wright State University Boonshoft School of Medicine Seed Grant and a grant from the Dayton Area Graduate Medical Association Consortium. The authors report no conflict of interest.
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Copyright
© 2007 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
