Current Sports Medicine Reports:
Extremity and Joint Conditions: Section Articles
Current Concepts: Rotator Cuff Pathology in Athletes — A Source of Pain or Adaptive Pathology?
Kuhn, John E. MS, MD
Vanderbilt University Medical Center, Nashville, TN
Address for correspondence: John E. Kuhn, MS, MD, Vanderbilt University Medical Center, 3200 MCE South Tower, 1215 21st Avenue South, Nashville, TN 37232; E-mail: firstname.lastname@example.org.
Magnetic resonance imaging (MRI) findings are common in patients and athletes with shoulder pain. Historically these anatomic derangements have been thought to be the source of the patient’s symptoms, and approaches have been focused on restoring the anatomy. This manuscript will address three objectives: 1) suggest that the approach to rotator cuff disease should be based on the patient’s history and physical examination, and not necessarily on the anatomic disorders apparent on imaging; 2) review the data that supports the contention that rotator cuff disease is not the source of pain in the symptomatic shoulder, and 3) describe the concept of adaptive pathology. The findings on the MRI in the thrower’s painful shoulder may be adaptive, and these alterations may be required to allow performance at high levels in sport.
Rotator cuff disease is detected easily on imaging studies and is seen often in athletes with shoulder pain. Imaging of the symptomatic shoulder in athletes and other patients often demonstrates rotator cuff tendinosis, partial tears of the rotator cuff, and full-thickness tears of the rotator cuff. Health care providers (and patients) assume that these findings are the source of the patient’s pain, leading to treatments — including surgery — to treat the rotator cuff disease. However there is a preponderance of evidence to suggest that this assumption may not be true. In fact, the pathology that we see on imaging in athletes may be adaptive — i.e., these alterations in anatomy may be required to allow performance in their sport, and surgical treatment to restore anatomy may prevent an athlete from returning to play at the same level.
This manuscript will address three objectives: 1) change the perspective of the approach to rotator cuff disease from anatomic to the one based on the patient’s history; 2) review the data that supports the contention that rotator cuff disease is not the source of pain in the symptomatic shoulder, and 3) describe the concept of adaptive pathology. The findings on the magnetic resonance imaging (MRI) in the thrower’s painful shoulder may be adaptive, and these alterations may be required to allow performance at high levels in sport.
Rotator Cuff Disease — Definitions and Considerations
Rotator cuff disease often is defined anatomically, following a spectrum from tendinosis to partial rotator cuff tears and to full-thickness tears; however this classification of disease may not be as helpful with regard to management decisions. Other features of rotator cuff disease such as the acuity of the injury and the precise nature of the patient’s symptoms (pain, loss of function, or weakness) may be more important.
Acute Traumatic Rotator Cuff Tears
Acute traumatic rotator cuff tears are characterized by a high-energy traumatic event. Patients who sustain an acute full-thickness rotator cuff tear typically have severe pain and an acute loss of significant function. They often cannot elevate their arm for days or weeks after the injury. A dislocation in a patient older than 40 years is a common mechanism of injury. MRI can be helpful to distinguish acuity, as in an acute traumatic rotator cuff tear, we would expect the muscle belly of the torn rotator cuff tendon to have little evidence of atrophy or fatty infiltration (characteristics of chronicity). In general, most orthopedists would consider an acute rotator cuff tear with loss of function a reasonable indication for rotator cuff repair. In fact, there is evidence to suggest that patients with acute tears will have better outcomes if the repair is done before 6 wk (2,37).
The Rotator Cuff Tear without a History of Injury
In contrast, many patients, particularly throwing athletes, present with a painful shoulder, no recognized acute injury, and imaging that demonstrates significant rotator cuff disease. Here the primary complaint is pain. Imaging may demonstrate rotator cuff disease, commonly, partial-thickness rotator cuff disease. Tears of the superior labrum and other pathology may also be seen. While this patient may have anatomic pathology, it would be careless and possibly detrimental to assume that the pathology is the source of the patient’s pain.
Symptoms: Pain or Weakness
Often in the literature, the nature of the patient’s symptoms is not clear (31). Patients with rotator cuff disease often present with pain, although weakness and/or loss of function are recognized as important symptoms as well. Many reports do not present the patient’s specific symptoms (31), and it can become difficult to define the indications for surgery as a result (13,35,50). Without question, it is of critical importance to identify clearly the nature of the patient’s symptoms. As will be described, symptoms of pain may not be related to the rotator cuff disease and may be treated without surgery. On the other hand, patients with weakness or loss of function unrelated to pain may require successful surgery to restore strength or function. Identification of the nature of the patient’s symptoms is important to direct appropriate treatment.
MRI Can Be Misleading
When assessing an athlete with shoulder pain, a thorough history and physical examination often can detect sources of pain that would not be apparent on static imaging. Examples include scapular dyskinesis and glenohumeral internal rotation deficit (23). In addition, it is known that MRI demonstrates findings that normally would be considered pathologic in asymptomatic people and in throwing athletes. In a systematic review to assess the prevalence of rotator cuff disease, Reilly et al. (40) demonstrated in asymptomatic subjects (average age, 44.3 years) who underwent MRI that the prevalence of partial-thickness tears was 15.9% and full-thickness tears was 10.3%.
A number of studies have reviewed findings seen in MRI studies of asymptomatic throwing athletes (6,17,19,21,34) (Table 1). The amount of “pathology” in these asymptomatic shoulders is surprising. While full-thickness rotator cuff tears are exceedingly rare, partial-thickness rotator cuff tears are common — as is labral damage. These data alone would have us question the assumption that the “pathology” seen on the MRI scan is the source of the patient’s shoulder pain, but there is other evidence as well.
Most People with Rotator Cuff Tears Do Not Have Surgery
As mentioned previously, the prevalence of rotator cuff tears is high. In asymptomatic subjects (average age, 44.3 years), the prevalence of full-thickness rotator cuff tears is 10.3% based on MRI and 21.7% based on ultrasound (40). From these data, we can derive a very conservative estimate that 10% of people older than 65 years have full-thickness rotator cuff tears. Then, based on the 2010 Census (49), we know that more than 5.7 million Americans have full-thickness rotator cuff tears. In the United States, approximately 275,000 rotator cuff repairs are done each year (5). With these data, it becomes clear that fewer than 5% of all people with full-thickness rotator cuff tears have surgery each year. Why these 5% have symptoms that direct them toward surgery and 95% do not is not clear, but without question, the overwhelming majority of people with full-thickness rotator cuff tears does not have surgery.
Failed Rotator Cuff Repairs Do Not Hurt
Rotator cuff repairs fail in approximately 30% of patients (14). If rotator cuff tears were painful, then it would stand to reason that failures of rotator cuff repairs should be painful. Interestingly this is not the case. In fact, numerous studies have demonstrated that patients who have failed their rotator cuff repairs have validated patient-reported outcome scores that are indistinguishable from those whose repairs heal (45). All patients improve with treatment, but it brings into question which treatment produced the benefit? Was it the index surgical procedure or the postoperative rehabilitation that was responsible for the improvement in the patient-reported outcome scores?
Pain and Duration of Symptoms Are Not Related to Rotator Cuff Tears
The MOON Shoulder Group reported on a prospective cohort of 452 patients with atraumatic symptomatic full-thickness rotator cuff tears treated with exercise (27). These patients completed validated patient-reported outcome measures, including data on the level of pain on a 10-cm visual analog scale and on the duration of symptoms. The authors also collected data on physical examination findings and anatomic features of the rotator cuff tear, including tear size, retraction, fatty infiltration, and superior humeral head migration among other features of rotator cuff tear severity. Interestingly neither pain (26) nor duration of symptoms (45) correlated with any measure of rotator cuff tear severity. These data suggest the patients’ severity and duration of symptoms may not be related to the rotator cuff tear. Interestingly low patient-reported outcome scores were correlated with the presence of scapular dyskinesis (18), indicating a role for exercise therapy in the treatment of these patients.
Exercise Effectively Treats Patients with Atraumatic Rotator Cuff Tears
The MOON Study (27) included 452 patients with atraumatic symptomatic full-thickness rotator cuff tears in a multicenter prospective cohort study. Pain was a dominant symptom. All patients followed a standard physical therapy program derived from a systematic review of the literature (24). Patients were assessed at entry, 6 and 12 wk, and 1 and 2 years. The effectiveness of the physical therapy program was surprising. At 12 wk, patients had statistically and clinically significant improvements in their validated patient-reported outcomes. Fewer than 20% of the patients failed nonoperative treatment and had surgery. The effect of the physical therapy program was robust, as patients who failed nonoperative treatment generally did so before 12 wk. The majority of patients treated successfully with nonoperative treatment continued to do well at 2 years. Interestingly the anatomy of the rotator cuff tear did not influence the decision for surgery; instead low expectations for nonoperative treatment were the strongest predictor for surgery (12). These data again support the contention that rotator cuff tears may not be painful and lead us to question the assumption that the findings noted on MRI are responsible for the patient’s symptoms. Why then do we see these changes?
The Concept of Adaptive Pathology
Throwing is an extreme skill that requires the glenohumeral joint to achieve incredible position and experience exceptionally high angular velocities and forces (11,15). In order to throw at high velocities, it has been recognized that a thrower must hit certain nodes to optimize this skill (9,11). These nodes are reproducible, consistent kinematic body positions that all pitchers achieve when throwing efficiently. Hitting these nodes optimizes proper pitching mechanics and may reduce injury. Additionally, as it has been shown that the velocity of the pitched ball correlates with the amount of external rotation of the abducted arm in the late cocking phase of throwing, these nodes likely optimize the body’s ability to maximize external rotation (16,37,48).
The forces and position of the shoulder at maximal external rotation are impressive, with the arm in a position of 165° + 11° (15). This position has been called a “critical moment” in throwing and is thought to be a potential source of the development of pathology in the thrower’s shoulder (4,15,43). This position produces high strain in the superior labrum (38) and superior labrum anterior posterior (SLAP) lesions in cadaver shoulder models (28,44). With regard to the rotator cuff, this position of maximal glenohumeral joint external rotation is thought to produce articular surface partial-thickness rotator cuff tears through compressive loads of internal impingement (20,47) or alternatively through external rotation tensile overload of the capsular portion of the rotator cuff (25,43). The repeated torsion in external rotation during throwing also leads to the remodeling of the thrower’s humerus in external rotation torsion (8,29,39). Bony remodeling also occurs on the scapular side of the dominant arm of the thrower with increased glenoid retroversion (8,10). Finally physical examination of asymptomatic professional baseball players demonstrates asymmetry in inferior laxity as detected by the sulcus sign (3). These changes are thought to be adaptive and even protective of the thrower’s shoulder (8,25,43), and these likely exist so that the thrower can deliver the ball at high velocity effectively.
The fact that MRI scans on asymptomatic throwers demonstrate significant findings that normally would be considered the source of the athlete’s pain (Table 1) suggests that these athletes have developed these findings in order to throw at high levels, just as their humerus has remodeled into greater retroversion. Chronic SLAP lesions in throwers may allow for increases in external rotation required for throwing. Articular side partial-thickness rotator cuff tears may represent failure of the capsule in external rotation, again allowing for extremes of external rotation required for high-level throwing. As such, the treatment of the thrower’s shoulder with symptoms should not focus on the MRI, as the findings seen may represent adaptations that allow the thrower to perform at high levels. Instead rehabilitation focused on the functional problems (scapular dyskinesis, core stability, and reduction of the glenohumeral internal rotation deficit) should be more successful than restoring the anatomy surgically.
Rehabilitation Is the Best Medicine
Rehabilitation is the cornerstone of treatment in the thrower with shoulder pain and rotator cuff pathology without a history of acute injury. Rehabilitation may be lengthy, and it is important to prepare the athlete accordingly. Details on rehabilitation can be found in the literature (23). In general, the rehabilitation program should be based on a comprehensive evaluation and should address core stability weakness, glenohumeral internal rotation deficits, and scapular dyskinesis (23).
Save Surgery to Salvage Careers
The surgical treatment of rotator cuff tears in the throwing athlete has received some study (1,7,22,30,33,36,41,42) (Table 2). With regard to partial-thickness tears, three different methods have been employed to treat surgically throwing athletes: debridement (1,36,41,42), repair of delaminated rotator cuff layers in situ (without repair to the bone) (7), and repair of the partial rotator cuff tear to the bone, restoring the anatomy to normal (22). In the high-demand population of throwing athletes, using return to play at the same or better level as a primary outcome, the results of surgical treatment of partial-thickness rotator cuff tears demonstrate moderate success (Table 2). Debridement of the partial-thickness tear allows the thrower to return to play at rates from 16% to 85% (1,36,41,42). There are little data on repair of the delaminated rotator cuff tear without repair to the bone, but the early results seem promising with return-to-play rates of 89% (7). When a throwing athlete has a partial tear that is repaired to the bone, the return-to-play rates seem less optimal, with only 1/3 returning to the same level of play (22).
In a similar vein, repair of full-thickness rotator cuff tears to the bone in throwing athletes is met with dismal return to throw rates (8% for professional pitchers) (30,33) (Table 2). These data suggest that the anatomic restoration of the rotator cuff has led to poorer outcomes than a debridement or repair in situ, supporting the contention that this “pathology” may be adaptive in some throwers. Because the return-to-play rates are poor in throwing athletes, surgery should be a career-salvaging approach undertaken only after the athlete has failed appropriate and complete rehabilitation.
In this era of evidence-based medicine, it is important to question our practice patterns if they have been built on dogma and not evidence. The principle that the findings on imaging are responsible for the patients symptoms and that anatomic restoration is the goal for treatment does not seem supported by data from multiple lines of evidence when considering patients with shoulder pain and MRI-documented rotator cuff disease. In throwing athletes with shoulder pain, the MRI can be extremely misleading. It is conceivable that the “pathology” seen on the MRI is adaptive as surgical restoration of anatomy is not associated with high return-to-play rates. In patients with atraumatic shoulder pain, appropriate rehabilitation focusing on core stability, glenohumeral internal rotation deficits, and scapular dyskinesis (all detected by physical examination and not MRI) is the essential treatment. Because the return-to-play rates for throwing athletes after rotator cuff surgery are poor, surgery should be considered a career-salvaging option. The throwing athlete can be considered on the edge of a cliff. The approach to treatment should put him back on the edge of the cliff and not restore his shoulder to normal.
No funds were received to produce this work.
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