Rotator cuff tears are one of the most frequent reasons for patients to visit an orthopaedic surgeon. Despite their prevalence, controversy still exists regarding the indications and timing of surgical repair. Recent clinical studies have shown that rotator cuff tears have very little capacity to heal without surgery1. Instead, tears become bigger over time; the tendons become retracted, degenerated, and scarred to surrounding structures; and the muscles undergo fibro-fatty infiltration and become stiff. All of these factors have negative implications for rotator cuff tendon-to-bone healing, and failure of tendon healing has been associated with poor clinical outcomes2.
The clinical literature on rotator cuff repair has largely focused on achieving anatomic healing. Therefore, little is known about how a retracted muscle-tendon unit functions following repair if healing does occur. Such is the topic of the article by Mannava et al. In this article, the authors used a rat model to show a significant decline in rotator cuff muscle function at the peak tensions required to repair acute tears (four weeks) and an even larger functional decline at the tensions required to repair chronic tears (twelve weeks). This led the authors to conclude that early repairs with less tension may improve postoperative muscle function and therefore outcomes.
This article represents an interesting and novel approach to maximizing rotator cuff repair outcomes. While the hypothesis and findings of this animal study are valid and interesting, the authors also point out that further investigation is required before definitive clinical recommendations can be made, and I concur.
The clinical importance of these findings is hard to quantify because few studies have correlated intraoperative repair tension with postoperative rotator cuff function. Davidson and Rivenburgh compared repair tensions with clinical outcomes and found that repairs that were performed with a high tension of >8 lb were associated with poor subjective and objective outcomes3. However, they did not evaluate tendon healing in their postoperative analysis. Therefore, it is unclear if these inferior results were due to inadequate muscle function or to incomplete tendon-to-bone healing, which is also adversely affected by high repair tensions4. Clarification of the clinical ramifications of a healed but dysfunctional rotator cuff would be useful moving forward.
Another clinical concern is how these findings evolve over time. In the study, the authors investigated one time point shortly after the application of tension. This is understandable given the limitations of in vivo muscle testing in an animal model. However, very few surgeons allow their patients to actively elevate the arm and contract the rotator cuff shortly after repair. Instead, the functional outcome of the rotator cuff repair is most applicable approximately six weeks following the application of tension, when most patients stop wearing a sling and begin to actively use the shoulder. Circumstantial evidence would suggest that the muscle would undergo little physiologic adaptation over this time. Studies have shown that rotator cuff muscle atrophy and fatty infiltration are irreversible following a single-stage repair5. As function follows structure, one would also assume that the decline in muscle function seen in this study is also irreversible. It will be interesting to see if this logic holds true with future studies.
While more work still needs to be done in this field, this study provides a previously under-recognized rationale for the expeditious repair of acute rotator cuff tears. It does not provide a rationale for the acute treatment of chronic tears. In other words, this study adds to the consensus that patients with a clearly defined traumatic event that results in shoulder pain and weakness with correlative imaging of a rotator cuff tear without degeneration are better served by immediate repair. This study does not attempt or profess to delineate the timing of surgery for patients who present with a chronic tear. Interpretation of this study should keep this in perspective.