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Reviewed & Edited by Austin Baraki, MD

Introduction

The “rotator cuff” is a set of four muscles around the glenohumeral joint including the supraspinatus, infraspinatus, subscapularis, and teres minor (see figure). These muscles all originate from the scapula, insert at various points on the humerus, and serve multiple coordinated functions including abduction, adduction internal rotation, external rotation, and stabilization. Each muscle is considered to have its own unique action on scapulohumeral movement (sometimes described as scapulohumeral rhythm, as discussed in the first installment of the shoulder series here).

Unfortunately, the cuff muscles are often viewed as both the source and the answer to the majority of shoulder pain and dysfunction. In addition to “impingement” (discussed here), pathology of the rotator cuff muscles including tears and tendinopathy are among the common narratives used to explain shoulder pain and dysfunction. We’ve already had an extensive discussion on the lack of evidence supporting such a reductionist approach to shoulder pain in our previous articles; however, given the persistence of these ideas in the rehab world and the general public, bear with us as we tackle rotator cuff tears next.

A muscle tear sounds really bad, right? But if we are going to call something a problem, its prevalence should — at least to some extent — differ between those who experience symptoms or complications, and those who don’t. So we must first look at the “base rate” of rotator cuff issues among those without pain or dysfunction: the “asymptomatic” population.

Rotator Cuff “Degeneration”: The “Gray Hair” of the Shoulder

Teunis et al. examined the prevalence of rotator cuff abnormalities with aging in a cohort of 4,331 patients. They found a total of 1,452 abnormalities, and reported that the:

 “overall prevalence of abnormalities ranged from 9.7% (29 of 299) in patients aged 20 years and younger and increased to 62% (166 of 268) in patients of 80 years and older.”

The authors state (emphasis ours):

“We identified a high rate of rotator cuff abnormalities in both symptomatic and asymptomatic patients, in the general population, and after shoulder dislocations, increasing with aged — a prevalence high enough for degeneration of the rotator cuff to be considered a common aspect of normal human aging. Whereas many surgeons favor a ‘‘wear and tear’’ theory, it is also possible, and in our opinion more likely, that the rotator cuff is subject to an inherent degenerative process similar to thinning and graying of the hair.”

This continues to cast doubt upon the mechanical narratives and pathologizing of rotator cuff tears, given how often we find them in the asymptomatic population with aging.

“Traumatic” vs. “Degenerative” Tears: A Case of Uncertainty

When a tear of the rotator cuff musculature is diagnosed, a dichotomy of “degenerative” (non-traumatic) or “acute” (traumatic) is usually applied. “Traumatic tears” are typically diagnosed when shoulder pain is attributed to a specific event that is assumed to be sufficiently traumatic to tear a cuff muscle/tendon. In contrast, “degenerative” tears are diagnosed when a preceding traumatic incident can’t be identified.

Why does this labeling system matter? Because the plan of care is typically altered based on the label applied.

If the tear is deemed “non-traumatic”, then a round of so-called “conservative” management (i.e., rehabilitation) is typically recommended prior to considering more invasive treatments like surgery. However, if the tear is labeled “traumatic”, then surgical intervention is likely to be recommended as soon as possible — though exactly how soon is debatable. (Chris Littlewood makes a compelling argument regarding the controversy around rotator cuff tears and their treatment in his editorial, The enigma of rotator cuff tears and the case for uncertainty).

The flaw with this diagnostic approach is that it’s actually quite difficult to determine whether a cuff tear is actually “new” and associated with the trauma, or whether it was already present, asymptomatic, and undetected until the clinical evaluation for new shoulder pain. But if we follow this line of thinking, we must have good evidence validating the need to surgically intervene on a rotator cuff tear … right?

As it turns out, we don’t.

Surgical Repair for Rotator Cuff Tears

From the traditional biomedical perspective, if we examine a painful shoulder and find a torn rotator cuff muscle, simply repairing the tear should result in prompt resolution of the pain or dysfunction. It just makes simple, logical sense, right? Of course, our readers should be familiar with how often this sort of reductionist biomedical reasoning has failed us in the past. So what does the evidence on surgery for rotator cuff tears tell us?

A 2017 meta-analysis by Ryösä et al synthesized data from 3 randomized controlled trials including a total of 252 participants were available comparing surgical versus conservative management outcomes. (It should be mentioned that this is a small number of studies and participants on which to perform a meta-analysis, and there was a moderate level of heterogeneity in the data. These factors should temper our confidence in the conclusions at this point in time.) After analysis, the authors conclude (emphasis ours):

There was no clinically significant difference between surgery and active physiotherapy in 1-year follow-up in improving Constant score or reducing pain caused by rotator cuff tear. As physiotherapy is less prone to complications and less expensive than surgery, a conservative approach is advocated as the initial treatment modality to rotator cuff tears.”

In a larger study, Khatri et al. examined the natural history of full-thickness, symptomatic rotator cuff tears by reviewing 57 randomized controlled trials involving 4542 total participants. The studies were grouped into three categories based on interventions:

  1.  Surgical repair,
  2. Acromioplasty alone,
  3. Non-operative treatment.

The authors’ findings (emphasis ours):

“There was an overall improvement in all arms from baseline for studies reporting the Constant score (Figure 3). When differences between operative and nonoperative arms were explored, this effect was sustained, with all study arms showing positive change. Treatment response in all outcome measures … showed an improvement in functional outcomes regardless of treatment intervention applied (Figure 4). Studies that followed up patients at multiple time points indicated an improvement in outcome in the first 12 months, after which the rate of improvement stabilized. This pattern was consistent irrespective of treatment type given (primary repair, acromioplasty only, or nonoperative intervention).

Since it seems we can often accomplish similar outcomes regardless of operative or non-operative treatment for rotator cuff tears, we should seriously question the efficacy and mechanistic justification for such invasive procedures. In other words: maybe the typical biomedical understanding of this topic is wrong.

Furthermore, if we can accomplish similar outcomes with two different treatment approaches, then the less risky option should be the treatment of choice. The authors conclude (emphasis ours):

“We show that patients with symptomatic full-thickness rotator cuff tears demonstrate a consistent and considerable response to treatment, even with nonoperative management. The largest improvement occurs in the first 12 months, after which the response stabilizes. When the treatment effect of invasive surgery is assessed, consideration must be given to the natural history of patients with rotator cuff tears to improve over time with nonoperative care as well.”

So even though it initially appeared to make perfect sense that repairing a tear would be the only way to treat a symptomatic rotator cuff tear, at this point it appears that the type and severity of tear have little, if any, bearing on treatment selection and outcomes. It also appears that most rotator cuff tears have a favorable natural history, with significant improvement over time regardless of intervention. These are very interesting findings that argue strongly against the traditional structurally-focused biomedical approach.

Should we be worried about tear progression?

Another common argument is the need for surgical intervention to prevent tear progression over time. This is a yet another reductionist approach to the topic — but if we are to follow this logic, what supportive evidence do we have? How concerned should we be about tear progression?

Kwong et al. performed a systematic review of the literature regarding the natural history of non-operative rotator cuff tears in symptomatic and asymptomatic populations. The primary outcome was progression of tear size of at least 5 mm as measured by MRI or Ultrasound. They identified 8 studies meeting their inclusion criteria (4 on symptomatic individuals and 4 on asymptomatic individuals) that included a total of 411 tears (255 asymptomatic and 156 symptomatic). Their findings:

“Of the 255 asymptomatic tears, 40.6% progressed during a mean follow-up period of 46.8 months (standard deviation, 20.1 months) compared with 34.1% of the 156 symptomatic tears at 37.8 months (SD, 17.4 months); this finding did not reach statistical significance (P = .65).”

“The average percentage progression per month in the asymptomatic and symptomatic groups was 0.85% per month and 1.00% per month, respectively (95% confidence interval [CI], 0.42%-1.28% per month and 0.53%-1.46% per month, respectively; P = .65).” [NB: no significant difference]

In other words, both asymptomatic and symptomatic tears progressed at similar rates, and don’t appear to progress significantly during 2-5 years. This finding further muddies the water on why shoulders become symptomatic — we don’t know, and it doesn’t appear to be as strongly correlated with the presence or severity of a tear as you might think. It further questions the necessity of surgical intervention based on the narrative of mitigating tear progression for fear of developing symptoms. The authors go on to state:

“This finding may reflect the fact that pain (i.e., symptoms), as the independent variable between the 2 groups in this study, remains a subjective measure of disease whereas the underlying tear characteristics (e.g., progression and size) and their contribution to nociception remain unclear.”

Non-surgical treatment

So how do patients do over time without surgery? Boorman et al. sought to answer this question in their study, The rotator cuff quality-of-life index predicts the outcome of nonoperative treatment of patients with a chronic rotator cuff tear. The authors studied the outcomes of a physiotherapy program for chronic (i.e., symptoms greater than 3 months) full-thickness rotator cuff tears in 93 patients.

Patient outcomes were categorized as “success” versus “failure” based on non-operative treatment. In other words, if the patient and surgeon ultimately elected to have surgery after 3 months of physiotherapy, then the case was deemed a “failure”.

The results showed that 75% of patients were classified as having a successful outcome at 3 month mark (i.e., the patient and surgeon elected to not pursue surgery). On the other hand, 23 patients (25%) were considered as “failed” nonoperative treatment, since they went on to undergo rotator cuff repair surgery. More interestingly, the two year follow-up data illustrate the nuances here:

“During the two years of follow-up, ten patients crossed over to the opposite treatment. Four patients who had originally been classified as having had a treatment failure experienced subsequent improvement and canceled their scheduled surgery. Six patients originally classified as having had a successful treatment experienced increased symptoms in the affected shoulder and underwent surgery. Four of the latter six patients fell and reinjured the shoulder, one injured the shoulder lifting a suitcase into the trunk of a car, and the sixth patient attributed her need for surgery to the daily struggle of dressing with compression stockings.”

Note that only six out of the 70 successful cases had worsening symptoms and underwent surgery over the 24 month follow-up period. The authors report that “these results suggest that a successful result at three months is most often durable over time.”

Fortunately, the authors also followed up on study participants at 5 years (What happens to patients when we do not repair their cuff tears? Five-year rotator cuff quality-of-life index outcomes following nonoperative treatment of patients with full-thickness rotator cuff tears). They report: “Between the 2- and 5-year follow-up periods, only 3 of 64 patients who had previously been defined as having a successful outcome became more symptomatic and underwent surgical rotator cuff repair. Of these 3 patients, 2 experienced a gradual worsening over time whereas 1 was doing very well until an errant golf swing significantly exacerbated his symptoms.”

Based on the Rotator Quality of Life Index, outcomes were not different between the successful versus failed group at 2 years and 5 year follow-up points (see table 2). Therefore, the authors conclude:

“Nonoperative treatment is an effective and lasting option for many patients with a chronic, full-thickness rotator cuff tear … While some clinicians may argue that nonoperative treatment delays inevitable surgical repair, our study shows that patients can do very well over time, no matter whether treated operatively or nonoperatively.

It appears that the base rate of rotator cuff tears increases with aging, and even if we deemed the tears as necessitating intervention, surgery doesn’t appear to be the best option for many cases. So if not surgery, then what should we be doing for patients presenting with shoulder pain who have been identified to have a rotator cuff tear?

Shoulder Injections

Injections are a very commonly offered therapy in orthopedic and sports medicine clinics. Typical injections are described to patients as a combination of “numbing” medicine (local anesthetic, e.g., lidocaine) in combination with an “anti-inflammatory” medicine (corticosteroid, e.g., triamcinolone acetonide).

A recent review of 13 studies by Cook et al. examined the short term (<3 months), mid-term (3-12 months), and long term (>1 year) outcomes of injection therapies. They looked at studies of corticosteroid injections with/without local anesthetic vs. local anesthetic alone, in order to clarify the specific effects of corticosteroids on outcomes.

For the 12 studies looking at short-term outcomes (<3 months):

  • 5/12 studies (4 of which had high risk of bias) favored corticosteroid injections.
  • 3/12 studies (1 of which had high risk of bias) showed improvements from corticosteroid injections in the initial 4-6 weeks, but no significant difference was observed at 12 weeks.
  • 4/12 studies (3 of which had high risk of bias) demonstrated no significant difference in short-term outcomes between the two types of injection therapy at any time point.

For the 5 studies looking at medium-term outcomes (3-12 months):

  • 2 studies (with high risk of bias) showed a significant difference in outcomes supporting corticosteroid injections.
  • 1 study (with high risk of bias) favored local anaesthetic injections for pain mitigation.
  • 2 studies (with low risk of bias) showed no significant difference in mid-term outcomes between the two types of injection therapy.

For the 2 studies looking at long-term outcomes (>1 year):

  • 1 study (high risk of bias) favoring corticosteroid injections
  • 1 study (low risk of bias) demonstrating no significant difference between injection groups.

The authors formulate a summary of best evidence:

In summary, [corticosteroid] injections may have better short-term results than anaesthetic-only injections in the first 8 weeks. There does not appear to be any convincing evidence from the studies of low or high risk of bias that [corticosteroid] injections confer additional benefit over anaesthetic-only injections after this time point.

Of note, many of the included studies had multiple concurrent interventions (such as exercise and NSAIDs) which may have affected the observed outcomes. It’s also worth emphasizing the important contextual effects and placebo benefits of injection therapies — i.e., a “theatrical” intervention injected directly to the perceived “source” of pain, and described to the patient as a potent combination of a numbing medication and a long-acting anti-inflammatory drug.

Most importantly, we need more data clarifying the risks versus benefits of corticosteroid injections in order to assess utility and efficacy. We may be dangling the carrot of pain relief in front of patients without a good grasp on the risks of corticosteroid injections compared to their short-term benefits. The authors end the discussion with a call to action:

Future research is needed that compares injections of CS, local anaesthetic, saline injections, needle only (for the mechanical effect), other products (eg, hyaluronate sodium) an advice only group, true placebo and a control group (to map natural history).

We actually do have emerging evidence questioning the efficacy of corticosteroid injections, though a detailed discussion of this topic will remain outside the scope of today’s article: 1) Increasing Numbers of Shoulder Corticosteroid Injections Within a Year Preoperatively May Be Associated With a Higher Rate of Subsequent Revision Rotator Cuff Surgery and 2) Preoperative Injections May Be an Iatrogenic Cause of Reoperation After Arthroscopic Rotator Cuff Repair.

Exercise

Jeanfavre et al. completed a systematic review to examine the efficacy of exercise therapy for full-thickness rotator cuff tears. The authors included studies on adults over 18 who underwent exercise therapy alone or in combination with other non-operative interventions for their tears. Outcomes included 1) pain, 2) range of motion, 3) strength, and 4) function of the affected shoulders.

The authors included 39 studies on a total of 2,010 shoulders from 1,913 subjects. Ages ranged from 23 to 80, with a mean of 64.1 years. Of the included shoulders, 1,462 were associated with a mechanism of injury, while 1,192 were deemed atraumatic. The duration of symptoms varied from 1 day to 5.5 years. Tear size was provided on 1,155 shoulders. (As an aside, note that figure 2 indicates 746 shoulders did not have tear size reported; which makes it difficult to conclude that a particular tear size necessitates surgery.)

Findings for Non-Operatively Treated Shoulders (i.e., no surgery):

  1. Pain – 790 / 923 (85%) shoulders reported improvement in pain, versus 133 shoulders that did not improve or not to a “satisfactory” level.
  2. Range of Motion – 1140 / 1369 (83%) shoulders reported improvements in range of motion versus 229 shoulders that did not improve or not to a “satisfactory” level.
  3. Strength – 514 / 598 (86%) shoulders reported improvement in strength versus 84 shoulders that did not improve or not to a “satisfactory” level.
  4.  Function – 1366 / 1610 (85%) shoulders reported improvements in function versus 217 shoulders that did not improve or not to a “satisfactory” level.
See Figure 3 and 4 for a representation of study type and outcomes as well as statistical significance vs clinical significance outcomes respectively.

It is worth noting that there was large variability in the exercise 

therapy treatments offered (See Figure 5). Programs included: strengthening, range of motion, stretching / flexibility, activity modification/education, home exercise program, manual therapy, heat/cold modalities, and postural interventions. The heterogeneity in exercise therapy is a major issue in accurately assessing the efficacy of exercise therapy, as less effective methods may be making those non-operative outcomes look worse than they otherwise would with more effective rehabilitation methods. We therefore need more well-conducted studies to assess what type and dose of exercise therapy is sufficient to reach clinically meaningful outcomes for patients.

The overall conclusions of the authors:

“The results of the current systematic review of the current literature provided few high-quality randomized control trials and a predominant number of observational studies, indicating GRADE B Recommendation (moderate strength) to support the use of [Exercise Therapy] in the management of [Full Thickness Tears]. There is substantial evidence to support the use of exercise therapy as first line management, especially in individuals >60 years of age with chronic, degenerative FTT. Future efforts should focus on coming to a consensus regarding exercises and interventions that are most effective in the conservative treatment of individuals with full thickness rotator cuff tears.”

What about Psychosocial factors?

According to Coronado et al, the typical biomedical factors thought to influence outcomes include:

  • Age
  • Rotator cuff tear size
  • Muscle Atrophy
  • Fatty infiltration
  • History of smoking
  • Medical comorbidities (such as diabetes and cardiovascular disease)

But what about the types of psychosocial factors we’ve talked about so frequently in the context of back pain? Do they influence outcomes here too? To preface this discussion, singling out a specific “type” of pathology like rotator cuff tears here continues to perpetuate a reductionist viewpoint and is a questionable approach. But with that said, let’s see what we have.

Coronado et al. completed a systematic review to examine whether certain psychosocial factors are associated with patient-reported outcome measures at initial consultation and post-treatment for patients with rotator cuff tears. Ten studies met the authors’ inclusion criteria (5 cross-sectional and 5 prospective cohort studies), totaling 1410 participants (age range from 46-62 years). Table 3 outlines the psychosocial factors examined. The authors conclude:

“The results of this review suggest that psychosocial factors, namely emotional or mental health, are associated to a weak to moderate degree with initial function or disability and pain in patients seeking operative treatment for rotator cuff tears, whereas expectation was the only factor associated with postoperative patient-reported outcomes. However, these findings were only observed in at most three studies. The lack of well-designed prospective studies in this area limits conclusions about the potential prognostic value of psychosocial factors.”

Overall, we need more data in this area. The authors did not find any studies assessing the association of psychosocial factors on patient outcomes in the context of non-operative treatments for rotator cuff tears, or among patients not actively seeking treatment at all. The authors also failed to find any cross-sectional data examining the association of fear-avoidance beliefs and pain catastrophizing on patient-reported outcomes.

However, we did discuss an article by Chester et al. in part 2 of our series, demonstrating how four specific psychosocial factors led to better outcomes related to physiotherapy for patients dealing with shoulder pain: 1) lower baseline disability, 2) patient expectation of “complete recovery” vs “slight improvement” due to physiotherapy, 3) higher pain self-efficacy, and 4) lower pain severity at rest.

Again, whether we should be separating out individual biomedical “issues” and assessing the effect of psychosocial factors on each one (e.g., differentiating effects on “shoulder impingement” vs. “rotator cuff tear” vs. others) is a point of debate that we don’t have a good answer to at this time. In support of this idea, Coronado et al. stated, “In patients with non-specific shoulder pain, associations between pain catastrophizing and fear have been previously reported”. They cite: George 2009, Lentz 2009, and Menendez 2015.

Take-home points

  1. We have evidence that rotator cuff tears appear in asymptomatic populations and increase in prevalence throughout life.
  2. Most symptomatic rotator cuff tears tend to follow a natural history of improvement over time (i.e., regression to the mean).
  3. Many clinicians operate from a false premise by dichotomizing traumatic versus nontraumatic rotator cuff tears to determine an appropriate course of action and choosing surgical repair for those deemed traumatic. Although the necessity of surgical repair is discussed with confidence by many clinicians, there is substantial evidence questioning the validity of surgical intervention and much more uncertainty exists.
  4. We have evidence of similar outcomes between surgical intervention and conservative (i.e., nonsurgical) management.
  5. Corticosteroid injection therapy appears to provide a small benefit in the short term (less than 8 weeks), but no clear benefit at any time point beyond that. We also have emerging evidence regarding risks of such injections.
  6. Exercise therapy appears to be the best course of action based on the totality of evidence. However, given the variability among exercise interventions studied, more well-conducted studies are required to determine the appropriate type and dose of exercise.
  7. We should also address psychosocial factors such as self-efficacy and patient expectations to increase the odds of positive long-term outcomes.
  8. Overall, the evidence is supportive of conservative management for rotator cuff tears, but whether a particular subset of cases necessitate surgical intervention remains unknown.

 


References

  1. Teunis T, Lubberts B, Reilly BT, Ring D. A systematic review and pooled analysis of the prevalence of rotator cuff disease with increasing age Journal of Shoulder and Elbow Surgery. 2014; 23(12):1913-1921.
  2. Littlewood C, Rangan A, Beard DJ, Wade J, Cookson T, Foster NE. The enigma of rotator cuff tears and the case for uncertainty Br J Sports Med. 2018; 52(19):1222-1222.
  3. Ryösä A, Laimi K, Äärimaa V, Lehtimäki K, Kukkonen J, Saltychev M. Surgery or conservative treatment for rotator cuff tear: a meta-analysis Disability and Rehabilitation. 2016; 39(14):1357-1363.
  4. Khatri C, Ahmed I, Parsons H, et al. The Natural History of Full-Thickness Rotator Cuff Tears in Randomized Controlled Trials: A Systematic Review and Meta-analysis Am J Sports Med. 2018.
  5. Kwong CA, Ono Y, Carroll MJ, et al. Full-Thickness Rotator Cuff Tears: What Is the Rate of Tear Progression? A Systematic Review Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2019; 35(1):228-234.
  6. Boorman RS, More KD, Hollinshead RM, et al. The Rotator Cuff Quality-of-Life Index Predicts the Outcome of Nonoperative Treatment of Patients with a Chronic Rotator Cuff Tear The Journal of Bone and Joint Surgery-American Volume. 2014; 96(22):1883-1888.
  7. Boorman RS, More KD, Hollinshead RM, et al. What happens to patients when we do not repair their cuff tears? Five-year rotator cuff quality-of-life index outcomes following nonoperative treatment of patients with full-thickness rotator cuff tears Journal of Shoulder and Elbow Surgery. 2018; 27(3):444-448.
  8. Cook T, Minns Lowe C, Maybury M, Lewis JS. Are corticosteroid injections more beneficial than anaesthetic injections alone in the management of rotator cuff-related shoulder pain? A systematic review Br J Sports Med. 2018; 52(8):497-504.
  9. Penning LIF, de Bie RA, Walenkamp GHIM. The effectiveness of injections of hyaluronic acid or corticosteroid in patients with subacromial impingement The Journal of Bone and Joint Surgery. British volume. 2012; 94-B(9):1246-1252.
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  11. Desai VS, Camp CL, Boddapati V, Dines JS, Brockmeier SF, Werner BC. Increasing Numbers of Shoulder Corticosteroid Injections Within a Year Preoperatively May Be Associated With a Higher Rate of Subsequent Revision Rotator Cuff Surgery Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2019; 35(1):45-50.
  12. Agarwalla A, Puzzitiello RN, Mascarenhas R, Sumner S, Romeo AA, Forsythe B. Preoperative Injections May Be an Iatrogenic Cause of Reoperation After Arthroscopic Rotator Cuff Repair Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2019.
  13. Jeanfavre. M, Husted S., Gretchen L. EXERCISE THERAPY IN THE NON-OPERATIVE TREATMENT OF FULL-THICKNESS ROTATOR CUFF TEARS: A SYSTEMATIC REVIEW. International Journal of Sports Physical Therapy. 2018; Jun: 13(3): 335-378.
  14. Coronado RA, Seitz AL, Pelote E, Archer KR, Jain NB. Are Psychosocial Factors Associated With Patient-reported Outcome Measures in Patients With Rotator Cuff Tears? A Systematic Review Clinical Orthopaedics and Related Research. 2018; 476(4):810-829.
  15. Chester R, Jerosch-Herold C, Lewis J, Shepstone L. Psychological factors are associated with the outcome of physiotherapy for people with shoulder pain: a multicentre longitudinal cohort study Br J Sports Med. 2018; 52(4):269-275.
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  17. Lentz TA, Barabas JA, Day T, Bishop MD, George SZ. The Relationship of Pain Intensity, Physical Impairment, and Pain-Related Fear to Function in Patients With Shoulder Pathology J Orthop Sports Phys Ther. 2009; 39(4):270-277.
  18. Menendez ME, Baker DK, Oladeji LO, Fryberger CT, McGwin G, Ponce BA. Psychological Distress Is Associated with Greater Perceived Disability and Pain in Patients Presenting to a Shoulder Clinic The Journal of Bone and Joint Surgery-American Volume. 2015; 97(24):1999-2003.

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