Delayed tendon reattachment does not reverse atrophy and fat accumulation of the supraspinatus — an experimental study in rabbits

Authors

  • Fujio Matsumoto,

    1. Bone and Joint Research Laboratory, University of Ottawa, Ottawa, Canada
    Current affiliation:
    1. Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1, Seiryomachi, Aobaku, Sendai 980-8574, Japan
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  • Hans K. Uhthoff,

    Corresponding author
    1. Bone and Joint Research Laboratory, University of Ottawa, Ottawa, Canada
    2. Division of Orthopaedic Surgery, University of Ottawa, Room 1319, Ottawa Hospital, General Campus, 501 Smyth Road, Ottawa, Ont., Canada K1H 8L6
    • Bone and Joint Research Laboratory, University of Ottawa, Ottawa, Canada. Tel.: +1-613-737-8377; fax: + 1-613-737-8837
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  • Guy Trudel,

    1. Bone and Joint Research Laboratory, University of Ottawa, Ottawa, Canada
    2. Division of Physical Medicine and Rehabilitation, The Rehabilitation Centre, 505 Smyth Road, Ottawa, Ont., Canada K1H 8M2
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  • Joachim F. Loehr

    1. Bone and Joint Research Laboratory, University of Ottawa, Ottawa, Canada
    2. Orthopädische Universitäts Klinik, Ratzeburger Allee 160, D-23562 Lübeck, Germany
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Abstract

Muscle atrophy and fat accumulation occur after rotator cuff tearing. Whether these changes are reversible after a successful repair is still unknown. Imaging allows only a semi-quantitative assessment of muscle atrophy and fat deposition. As only experimental studies permit a quantification of both, a unilateral detachment and wrapping in a polyvinylidine fluoride membrane of the supraspinatus was done in 22 rabbits. After 12 weeks, the polyvinylidine fluoride membrane was removed in 10 rabbits and the tendon inserted into a bony trough. The opposite shoulder served as control. All rabbits were killed at 24 weeks. Accumulation of fat on the muscle surface as well as between the muscle fascicles and occasionally in the sarcoplasm was increased in both experimental groups when compared to controls (non-reattached 12.8%, reattached 23.5% vs controls 5.4%; all p < 0.005). The muscle atrophy was significant (non-reattached 9.2 ml, reattached 9.1 ml vs controls 10.7 ml; both p < 0.005). Neither atrophy nor fat accumulation were reversed by surgical reattachment of the supraspinatus tendon. On the contrary, the fat accumulation was higher in the reattached group (p < 0.005). The trauma of reattachment, the delay between detachment and reattachment or an insufficient duration of recovery may have contributed to both, the lack of reversibility of supraspinatus atrophy and fat accumulation. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

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