Partial-Thickness Supraspinatus Tears: Do We Know How to Treat Them?

Miguel Angel Ruiz Iban, MD, PhD, SPAIN Jose Luis Avila Lafuente, MD, SPAIN Umile Giuseppe Longo, MD, MSc, PhD, Prof., ITALY

ISAKOS Newsletter   Current Perspective 2024   Not yet rated

Introduction

Partial-thickness tears of the posterosuperior rotator cuff are frequent problems that present particular challenges to the shoulder surgeon. The underlying physiopathology of partial-thickness tears is variable. In older adults, a partial tear develops in the context of the wide spectrum of rotator cuff disease. First, intrinsic and extrinsic factors cause the day-to-day insult to the tendons. Unsatisfactory tendon healing then leads to tendinopathy, followed by partial and full-thickness tears and, ultimately, rotator cuff arthropathy.In younger, active patients who practice overhead sports, repeated external rotation movement in abduction causes posterosuperior impingement between the supraspinatus and the posterosuperior glenoid and a partial articular tear can develop. More rarely, a partial tear can develop in the context of a traumatic injury.

The most controversial issues related to the management of partial-thickness tears are the precise diagnosis of the problem, the decision-making algorithm to indicate a surgical procedure, the selection of the best procedure for each tear, and the use of biological alternatives for management. The objective of this Current Perspective is to offer a critical review of the standard of care of these patients in order to stimulate discussion on these specific issues.

The Diagnosis Conundrum of a Partial Supraspinatus Tear

The typical patient with a degenerative partial tear has signs and symptoms of subacromial pain and a varying degree of stiffness or biceps symptoms at the time of consultation. After history-taking and physical examination, imaging techniques show a partial tear of the supraspinatus, and the diagnosis is made.

This straightforward diagnostic workup has several limitations as most subjects who present to a consultation because of shoulder pain with symptoms consistent with subacromial pain and impingement either have no altered cuff anatomy or present with only mild tendinopathy; often, the symptoms are not directly related to the cuff tendons but rather to inadequate scapulothoracic kinematics1. Moreover, when a partial tear is present, it is difficult to properly assess the tear with an isolated physical examination: impingement tests have sensibilities and specificities of <60%, and differentiating a partial tear from a full-thickness tear is often impossible. Even standard magnetic resonancee imaging (MRI) has sensitivity and specificity values of <70% and <40%, respectively.

Diagnosis is further complicated by the high incidence of asymptomatic partial tears. Ultrasound examination of asymptomatic shoulders will identify partial supraspinatus tears in 15% of the population, and 18% of English women >64 years of age have asymptomatic partial tears. In younger, active subjects, the issue is even more relevant: 50% of university-level Japanese baseball players or international-level handball players had asymptomatic partial tears.

Thus, it is naïve to assume that all patients with subacromial pain and impingement symptoms have a partial-thickness tear. The surgeon should consider carefully whether other issues, specifically scapular dyskinesis, frozen shoulder, and biceps problems, might be causing the symptoms instead of a partial tear that might be perfectly asymptomatic.

To Operate or Not To Operate: That is the Question

Once it has been established that a partial-thickness posterosuperior cuff tear is present and is the cause of the symptoms, the clinician should consider the best treatment for the patient. There is limited information on the natural history of partial tears than can guide the surgeon to decide on whether or not to consider surgery. It has been reported that 20% of symptomatic bursal-sided tears will progress in size within 24 months; but even in patients with substantial symptoms who are scheduled for surgery, delaying surgery for 6 months might avoid surgery altogether in one-third of cases, without compromising surgical outcomes for the rest.

Partial-Thickness Supraspinatus Tears: Do We Know How to Treat Them?

Similarly, while 60% of asymptomatic tears will progress in size after 5 years, only 10% of symptomatic tears will progress in size at 2 years; again, delaying surgery in these cases might avoid surgery in one-fourth of cases, without worsening clinical outcomes of the surgical procedure for the rest. Thus, the focus is usually placed on identifying factors that will predict progression of the tear: higher-grade tears, larger tears, tears that affect the posterior biceps pulley or the rotator cable, and tears that have been symptomatic for a longer period of time have been known to progress more frequently and to have persistent symptoms over time. Tears with these characteristics are often considered for surgery.

However, proceeding with surgery simply because of the fear of tear progression might be misguided. First, even in cases of high-risk tears, there is a reasonable chance that the tears might remain stable and asymptomatic over the long term. Second, the surgical procedure in cases of progression (even progression to a mid-sized full-thickness tear) is very similar in scope, success rate, and recovery time as compared with the current treatments for partial-thickness tears. Third, there are very limited long-term data on the efficacy of any surgical procedure for the management of partial-thickness tears, and it is unclear whether surgery has any impact on the natural history of rotator cuff disease2. Thus, conservative treatment needs to be considered as it has been shown to be effective3, and repeated imaging and clinical assessment every 6 to 12 months might be the best option for most degenerative tears. On the contrary, if the patient has persistent symptoms and functional deficits for an extended period of time despite appropriate conservative management, there is no reason to delay the procedure.

The Repair vs. Complete-and-Repair Dilemma

There are three classical alternatives for the surgical management of partial-thickness posterosuperior tears: debridement (Fig. 1), isolated repair of the layer affected (Fig. 2), and completion of the tear to a full-thickness tear followed by repair. The merits of debridement are difficult to assess, although good clinical outcomes have been reported. However, the debridement itself has no effect on the biomechanical environment, and, from a biological perspective, it is uncommon to find substantial inflammation of the tissue to be debrided. Both of these findings should raise the questions of (1) whether the available literature data was obtained from subjects who presented in fact an asymptomatic partial tear, and (2) whether other associated procedures (such as biceps tenotomy), or the postoperative rehabilitation routine, had a greater impact on the improvement observed in those patients.

Both isolated repair of the affected layer and complete-and-repair have shown to be effective for the management of rotator cuff tears, and both procedures have benefits and disadvantages.

01 A low-grade articular-side partial tear of the anterior supraspinatus in a left shoulder as viewed from the posterior portal (A). The partial tear is debrided with a shaver placed through the rotator interval (B) until good-quality tendon is reached (C).

02 A transtendinous repair of a partial articular tear of the supraspinatus in a left shoulder. Once the tear is debrided (A), the footprint is prepared (B) and an anchor is placed through a stab incision on the intact supraspinatus (C) and is placed on the exposed footprint (D). Next, a needle is used to carefully drive through the sutures through articular layer (E and F); these sutures are retrieved and tied in the subacromial space (G), yielding a good-looking repair from the articular space (H).

Isolated repair of the affected layer has the advantage of keeping the remaining, non-affected, tendon intact, but it might be more technically demanding because (1) many bursal tears have very poor-quality remnants in the bursal side; these are difficult to repair properly because of lack of good quality tendon and thinness of the remnant, (2) a proper transtendinous technique that restores the previous anatomy is challenging in cases of articular tears, as there is controversy on whether to include the capsule in the repair and on how to perform a proper repair that brings the torn layer back to place without causing over tension of the intact bursal layer, and (3) transtendinous repair of partial articular tears can be associated with postoperative pain and stiffness. Complete-and-repair techniques sacrifice the remaining tendon (and with it the healthy enthesis) but are more straightforward from a technical standpoint, and the repair of the newly developed full-thickness tear has consistent good results. Despite these differences, the longer-term clinical outcomes of both techniques seem to be similar, and it is clear that in both cases a retear (meaning the development of a full-thickness tear after surgery) can occur in up to 10% of cases4. It is a tough day when, as a surgeon, you find yourself in the position of explaining to a patient that, after you repaired her “partial” tear, she has ended up with a “full” tear.

When addressing a partial-thickness tear, the surgeon should carefully consider the quality of the remaining tendon attachment, examining it both from the subacromial and glenohumeral spaces and probing it to assess its firmness and elasticity. The size of the remaining tendon is less important than its quality: if the tendon “looks and feels” good, then a repair of the layer affected should be attempted, as the intact tendon enthesis (Fig. 3) will never be reproduced if the tear is completed. If the quality of the remaining tendon is questionable, then completing the tear and performing a technically easier repair is probably the best alternative.

03 A histologic sample of the supraspinatus-to-humerus enthesis of a healthy young rabbit. It can be clearly appreciated how the tendon tissue converts to a chondral tissue that progressively calcifies into normal-looking cancellous bone.

The (Un)Fulfilled Promise of Biological Alternatives

Three biological strategies have been suggested for the management of partial posterosuperior tears: mesenchymal stem cells, platelet rich plasma (PRP), and recently, a bioinductive collagen implant.

Mesenchymal stem cells bring with them the promise of restitutio ad integrum, as complete healing of the tendon and restoration of the native enthesis have been demonstrated in animal studies. Unfortunately, much like

the expectations associated with nuclear fusion, the healing potential expectations that stem-cell therapies have brought to orthopaedic surgeons over the past 40 years always still seem to be 10 to 15 years away. There is little if any evidence available to support its use today in partial-thickness tear, either as standalone treatment or as adjuvants to different repair techniques.

PRP is often considered as an alternative to expensive, difficult-to-obtain stem cells. Platelets are abundant, autogenic, and easy to extract and deploy. They are also full of a complete litany of exotic growth factors that carry in their own names the promise (again) of tendon-healing. With this in mind, different researchers have used them extensively to treat partial-thickness tears. It is unclear what is, among the myriad possible purification techniques, the best way to extract the platelets, and where and how many times the platelets should be injected. Despite these hurdles, different authors have found that applying PRP over the diseased tendon with an ultrasound guided injection is effective and safe, at least in the short term, to manage the symptoms of partial-thickness tears. Achieving the desired healing of the tendon is another issue that has not been resolved3.

Recently, a bioinductive collagen implant made from denaturalized collagen of bovine origin has been proposed as another biological alternative for the management of partial-thickness cuff tears. The implant is arthroscopically inserted over the bursal side of the torn tendon and fixed with specific staples to the underlying tendon without further procedures done to the torn tendon. The implant is infiltrated by tendon cells from the underlying tendon, and eventually is reabsorbed, leaving additional tendon-like tissue at the grafting site. When applied over a bursal tear, the implant integrates and helps in the healing of the damaged bursal layer (Fig. 4); when used over an articular partial tear, the extra tendon provided in the subacromial layer protects the tensioned remaining fibers and, once integrated, effectively lateralizes the footprint of the tendon. There is both animal and human evidence that these mechanisms do indeed happen when managing partial rotator cuff tears with this implant, and there is increasing evidence that the use of the bioinductive implant improves the clinical outcomes and the anatomy of the diseased tendon5. An ongoing randomized controlled trial, comparing this new alternative to traditional complete-and-repair, will soon shed light on the true usefulness of this new tool.

04 The proposed mechanism of action of the bioinductive collagen implant over a bursal-sided tear. The bursal-sided degenerative partial tear is patent with the lateral footprint exposed and no signs of any remaining repairable bursal layer (A). After the tendon is subtly debrided and the footprint is prepared, the collagen implant is placed over the injured tendon and is fixed with staples (B). Over time, tendon cells infiltrate the collagen implant, the implant reabsorbs, and new tendon is formed in its place (C).

Conclusion

The management of partial articular tears of the posterosuperior cuff is challenging. In a patient with a symptomatic partial tear, the clinician should focus their diagnostic skills on trying to identify other factors that might be the cause of the symptoms and should not consider every partial tear that is “found in the scene” as the culprit, as most of these tears are asymptomatic. When the partial tear seems indeed to be the cause of the symptoms, caution should be warranted before proceeding to surgery, as conservative treatment is often effective and many of these tears become asymptomatic and do not progress over time. Once surgery is considered, both traditional techniques (isolated repair of the affected layer or completion of the tear and repair) are useful and reasonably effective, but the key is defining if the remaining tendon is healthy enough; if this is the case, the intact tendon with its beautiful, intricate enthesis should be kept when possible. Finally, biologic alternatives are available, and PRP might be useful for providing short-term clinical improvements in some patients. The role of newer inductive collagen implants for this indication is becoming clearer, and seems to be promising, but its true long-term efficacy is yet to be proven.