Copyright © 2006 by The Journal of Bone and Joint Surgery, Inc.
Commentary & Perspective
Commentary & Perspective by
Jon K. Sekiya, MD*,
Center for Sports Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
The purpose of the study by Fuchs et al. was to assess the structural integrity and changes of the rotator cuff muscles following open repair and to correlate the structural results of the repair with the clinical outcome. The authors evaluated thirty-two consecutive single-tendon open rotator cuff repairs (twenty-two supraspinatus tendon repairs and ten subscapularis tendon repairs) that included the use of modified Mason-Allen transosseous sutures passed through a bone bridge and tied over a titanium plate. The patients were followed for a minimum of two years. For eighteen patients, preoperative magnetic resonance imaging studies were also available for comparison. Outcome measures included the relative Constant score that was compared with age and gender-matched normal values, the subjective shoulder value, and postoperative magnetic resonance imaging. Magnetic resonance imaging was used to assess healing of the rotator cuff repair, cross-sectional area was calculated to assess muscle atrophy, and the Goutallier classification was used to assess fatty replacement and infiltration1.
An important finding of the study was that while a successfully healed rotator cuff repair did not improve preoperative muscle atrophy, it did halt the progression of the atrophy. In addition, while preoperative atrophy was not predictive of a failed repair, postoperative atrophy was significantly higher in retears. In addition, with supraspinatus tears, fatty infiltration increased following successful repair in both the repaired muscle as well as the infraspinatus. These findings suggest that while a successful rotator cuff repair does potentially alter the natural history of the disease process, it does not normalize it. This also suggests that when the rotator cuff tendon ruptures, there are irreversible changes that occur that can't be altered even with a successfully healed repair1. This is supported by research in animal models that showed that chronic changes following rotator cuff detachment result in a muscle tendon unit that is not just shorter, atrophic, and with increased fatty infiltration, but that is also biomechanically stiffer2.
Another finding of the study was that while successful single-tendon open rotator cuff repair of the supraspinatus or subscapularis tendon does result in improved subjective and objective measures and patient satisfaction, healed repairs are not associated with improved clinical outcomes as determined by the Constant score. This is a particularly interesting finding given that this is the whole reason that we are doing the operation.
This study finding could be due to multiple factors. There may not have been enough power or a large enough sample size to detect a significant difference when one truly exists (type-II error). The authors admit in the discussion that, given the low number of reruptures (four only), their findings do not disprove the conclusions of other studies that healed repairs do better than those that rerupture3,4. Other potential reasons why no difference was detected between healed repairs and retears include the use of an outcome measure that may not be sensitive enough to detect small differences between the two groups. The Constant score is a popular shoulder scoring system initially reported back in 1987, but recently, some have criticized its validity and sensitivity5,6. Other scoring systems with validated outcome measures have been developed with more responsive questions that are sensitive to smaller changes. Perhaps outcomes utilizing these more sensitive scoring systems may have been able to detect clinically important differences despite the small sample size. In addition, it is likely that subjective shoulder pain and function in patients with single-tendon supraspinatus or subscapularis tears is actually a multifactorial process, with many variables responsible for outcome, and that a healed tendon repair is just one of many predictive variables. Also, it is possible that converting a larger tear to a smaller one may be responsible for subjective improvement, especially when the overall shoulder muscle balance of the smaller tear is improved. Others have found that rotator cuff repairs that failed did not have poorer outcomes than those that healed7. In addition, many other studies have shown that a failed rotator cuff repair still had significant (p < 0.05) objective and subjective improvements and satisfactory clinical outcomes3,4,7,8. Clearly, there are likely many other potential predictive factors at work that we do not yet understand.
The strength of the study by Fuchs et al. is that this information provides objective data on what is actually being performed—a rotator cuff repair. Directly comparing the status of the repair—whether it has healed, retorn, developed atrophy or fatty infiltration—and linking this with the clinical outcome helps us sort out which improvements are due the tendon-healing, which ultimately will assist us in determining how to successfully alter the natural disease progression.
The weakness of the study is that this is a heterogeneous group of patients. Supraspinatus and subscapularis tears and repairs are very different entities that require different surgical approaches (e.g., deltoid detachment and reattachment) and different postoperative regimens. In addition, the supraspinatus and subscapularis muscles are responsible for different shoulder functions. The number of subscapularis tendon repairs in this report is relatively small (ten patients). Because of these differences, it is difficult to make any meaningful comparisons between the two groups, and these should be considered two separate studies.
Nonetheless, this is a well-done study that answers several questions of clinical importance. Equally important, this study provides the background and basis on which to ask the next questions—specifically, what are the factors that lead to a successful clinical outcome following the surgical management of rotator cuff tears, and how do we alter the natural history and progression of repaired rotator cuff muscles with regard to tendon atrophy and fatty infiltration?
What will be required is a multivariate analysis of a large, multicenter, prospective cohort study of rotator cuff tendon repairs, evaluating both preoperative and intraoperative variables and linking these to both objective and validated patient-reported outcomes. This will help us sort out which variables are most clinically important and will enable us to predict which patients will most likely have healing following rotator cuff repair and which patients will most likely have failure to heal. In addition, determination of these patient variables may also help us to predict which patients will do well despite failure of healing of the repair and which patients will do poorly despite healing of the repair. This will allow us to better direct our patient selection and surgical technique toward variables that are clinically important, and to better counsel our patients and select surgical candidates for optimal outcome.
*The author did not receive grants or outside funding in support of his research for or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. A commercial entity (Arthrex) paid or directed, or agreed to pay or direct, benefits to a research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.
References
1. Goutallier D, Postel JM, Gleyze P, Leguilloux P, Van Driessche S. Influence of cuff muscle fatty degeneration on anatomic and functional outcomes after simple suture of full-thickness tears. J Shoulder Elbow Surg. 2003;12:550-4.
2. Safran O, Derwin KA, Powell K, Iannotti JP. Changes in rotator cuff muscle volume, fat content, and passive mechanics after chronic detachment in a canine model. J Bone Joint Surg Am. 2005;87:2662-70.
3. Harryman DT 2nd, Mack LA, Wang KY, Jackins SE, Richardson ML, Matsen FA 3rd. Repairs of the rotator cuff. Correlation of functional results with integrity of the cuff. J Bone Joint Surg Am. 1991;73:982-9.
4. Gerber C, Fuchs B, Hodler J. The results of repair of massive tears of the rotator cuff. J Bone Joint Surg Am. 2000;82:505-15.
5. Constant CR, Murley AH. A clinical method of functional assessment of the shoulder. Clin Orthop. 1987;214:160-4.
6. Kirkley A, Griffin S, Dainty K. Scoring systems for the functional assessment of the shoulder. Arthroscopy. 2003;19:1109-20.
7. Klepps S, Bishop J, Lin J, Cahlon O, Strauss A, Hayes P, Flatow EL. Prospective evaluation of the effect of rotator cuff integrity on the outcome of open rotator cuff repairs. Am J Sports Med. 2004;32:1716-22.
8. Jost B, Pfirrmann CW, Gerber C. Clinical outcome after structural failure of rotator cuff repairs. J Bone Joint Surg Am. 2000;82:304-14.
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