The ability of rotator cuff tendons to heal back to bone following injury is limited, and failure of surgically repaired rotator cuff tears in humans has been reported in 20-70% of cases. Many factors outside of the surgeon's control contribute to the limited healing potential including patient age, tear size, and time from injury to repair. However, two important factors that are within the surgeon's control are surgical repair technique and post-operative rehabilitation protocol. While much research has been done on surgical repair technique, surprisingly, very little data in regard to post-operative rehabilitation protocols following tendon to bone repairs in the shoulder are available to guide clinicians. As a result, the current clinical trend to passively mobilize the shoulder shortly after repair, which is fraught with a high incidence of failure currently, has relied on data from tendon to tendon healing in the hand. However, data from our animal model and that of others indicates that the response of tendon to activity may be different when healing to bone rather than to tendon. We recently developed an animal model in which healing of the rotator cuff tendon to bone insertion site could be carefully evaluated as a function of post-operative activity level. Immobilization was found to result in better healing than either cage activity or exercise and the longer the period of immobilization, the better the insertion site properties. Based on these results, we now hypothesize that remobilization after a sufficient period of immobilization will lead to improved insertion site mechanical and structural properties compared to immobilization alone. A period of immobilization will be necessary to 'protect'the insertion site and to allow for appropriate extracellular matrix (EGM) expression (e.g., type and III collagen, aggrecan, decorin and biglycan) such that the insertion site can re-form. Thus, the positive effect of remobilization requires a minimum period of immobilization.
The specific aims are: 1) Following repair, immobilize shoulders either continuously, or with passive motion, and compare insertion site mechanics, collagen fiber orientation and ECM gene expression at 2, 6, 10, 14, 18 and 22 weeks post-repair, 2) Following repair, immobilize shoulders for 2, 6 and 10weeks, then remobilize for 4, 8 and 12 weeks and compare insertion site mechanics, fiber orientation, and ECM gene expression to immobilization only at matching post-repair time points as well as over time, and, since immobilization has been shown to reduce range of motion, 3) Compare passive range of motion (ROM) prior to repair, immediately after immobilization has been discontinued, and after 3 ofays, 1, 2 and 6 weeks of remobilization.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR051000-05
Application #
7774339
Study Section
Skeletal Biology Structure and Regeneration Study Section (SBSR)
Program Officer
Panagis, James S
Project Start
2006-03-01
Project End
2012-02-28
Budget Start
2010-03-01
Budget End
2012-02-28
Support Year
5
Fiscal Year
2010
Total Cost
$288,148
Indirect Cost
Name
University of Pennsylvania
Department
Orthopedics
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Thomas, Stephen J; Miller, Kristin S; Soslowsky, Louis J (2012) The upper band of the subscapularis tendon in the rat has altered mechanical and histologic properties. J Shoulder Elbow Surg 21:1687-93
Peltz, Cathryn D; Hsu, Jason E; Zgonis, Miltiadis H et al. (2012) Intra-articular changes precede extra-articular changes in the biceps tendon after rotator cuff tears in a rat model. J Shoulder Elbow Surg 21:873-81
Peltz, Cathryn D; Hsu, Jason E; Zgonis, Miltiadis H et al. (2011) Decreased loading after rotator cuff tears leads to improved biceps tendon properties in a rat model. J Shoulder Elbow Surg 20:698-707
Peltz, Cathryn D; Sarver, Joseph J; Dourte, Leann M et al. (2010) Exercise following a short immobilization period is detrimental to tendon properties and joint mechanics in a rat rotator cuff injury model. J Orthop Res 28:841-5
Ward, Samuel R; Sarver, Joseph J; Eng, Carolyn M et al. (2010) Plasticity of muscle architecture after supraspinatus tears. J Orthop Sports Phys Ther 40:729-35
Dourte, LeAnn M; Perry, Stephanie M; Getz, Charles L et al. (2010) Tendon properties remain altered in a chronic rat rotator cuff model. Clin Orthop Relat Res 468:1485-92
Sarver, Joseph J; Dishowitz, Michael I; Kim, Soung-Yon et al. (2010) Transient decreases in forelimb gait and ground reaction forces following rotator cuff injury and repair in a rat model. J Biomech 43:778-82
Perry, Stephanie M; Getz, Charles L; Soslowsky, Louis J (2009) After rotator cuff tears, the remaining (intact) tendons are mechanically altered. J Shoulder Elbow Surg 18:52-7
Peltz, Cathryn D; Dourte, Leann M; Kuntz, Andrew F et al. (2009) The effect of postoperative passive motion on rotator cuff healing in a rat model. J Bone Joint Surg Am 91:2421-9
Perry, Stephanie M; Getz, Charles L; Soslowsky, Louis J (2009) Alterations in function after rotator cuff tears in an animal model. J Shoulder Elbow Surg 18:296-304

Showing the most recent 10 out of 11 publications