Rotator cuff tears: prevalence and management

                              Rotator cuff tears: prevalence and management

                                                                Dr KS Dhillon

Anatomy of rotator cuff
 

The rotator cuff consists of four muscles that arise from the scapula and and insert on the proximal humerus. The four muscles are, the supraspinatus, infraspinatus, teres minor and the subscapularis. The supraspinatus arises from the supraspinatus fossa, the infraspinatus from the infraspinatus fossa and teres minor from the lateral border of the scapula. All three insert on the greater tubercle of the humerus, with the supraspinatus most proximally and the teres minor most distally and the infraspinatus in between the two. The subscapularis arise from the subscapular fossa and inserts on the lesser tubercle.Though superficially the four muscles are separate,the deeper portions merge with each other and with the glenohumeral capsule and the long head of the bicep tendon.
The subscapularis is an internal/medial rotator and acts together with the latissimus dorsi, pectoralis major, and the teres major to produce medial rotation of the humerus. The infraspinatus is a strong external/lateral rotator and is assisted by the teres minor which is a weak rotator. The supraspinatus is the initiator of abduction of the shoulder and after 30 degrees of abduction the deltoid takes over. Besides producing rotation and abduction forces, the rotator cuff muscles lock the humeral head in the glenoid and provide a stable scapulohumeral link for upper limb function. They also provide muscle balance and capsular stability for the glenohumeral joint (1).

Prevalence of rotator cuff tears

Chronic shoulder pain is the most common orthopedic complaint after knee pain. Atraumatic rotator cuff tear is a frequent cause of pain and dysfunction of the shoulder in individuals over the age of 60 years and is present in about half of the patients with a history of shoulder complaints.
Rotator cuff tears may or may not be symptomatic. Tempelhof et al (2) studied the prevalence of rotator cuff tears in asymptomatic shoulders.They did a prospective clinical and ultrasonographic study in 411 volunteers. They found that the  overall incidence of rotator cuff tear was 23%. The incidence in the age group between 50 to 59 years was 13%, 60 to 69 years was 20%, 70 to 79 age group it was 31% and above 80 years it was 51%. The authors concluded that ‘rotator cuff tears must to a certain extent be regarded as "normal" degenerative attrition, not necessarily causing pain and functional impairment’.
Milgrom et al (3) studied the integrity of the rotator cuff using ultrasound in 90 asymptomatic adults between the age of 30 to 99 years. They found no significant difference between the dominant and nondominant arm as well as between genders. The found that the prevalence of partial and full thickness tears of the cuff increased markedly after the age of 50 years. Rotator cuff tears were present in 50% of dominant shoulders in the seventh decade and in 80% of subjects after the age of 80 years. They concluded that ‘that rotator-cuff lesions are a natural correlate of ageing, and are often present with no clinical symptoms’ hence logically ‘treatment should be based on clinical
findings and not on the results of imaging’.
Reilly et al (4) reviewed the literature to study the cadaveric and radiological prevalence of rotator cuff tears. The prevalence of cadaveric partial tears was 18.49% and cadaveric complete tears was 11.75% (total 30.24%). The ultrasonic incidence of tears in asymptomatic subjects was 38.9% and symptomatic subjects 41.4%. The incidence of MRI tears in asymptomatic subjects was 26.2% and in symptomatic subjects it was 49.4%. The authors concluded that rotator cuff tears are frequently asymptomatic and  radiological findings of rotator cuff tears should be correlated with clinical findings.
Yamamoto et al (5) did a population based study to elucidate the true prevalence of rotator cuff tears regardless of the presence or absences of symptoms. They examined clinically and with ultrasound, 683 people (1366 shoulders) in a village in Japan. There were 229 males and 454 females with an average age of 57.9 years (22 to 87 years). They found a 20.7% prevalence of rotator cuff tears. In symptomatic subject the incidence of tears was 36% and in asymptomatic subjects the incidence was 16.9%. They found that age, dominant arm and trauma were risk factors for tears of the rotator cuff.
In an another population based study, Minagawa et al (6) used ultrasound to elucidate the prevalence of rotator cuff tears in symptomatic and asymptomatic individuals. Out of 664 subjects studied 147 (22.1%) had full thickness tears of the rotator cuff.In the 20 to 40 age group the incidence was 0%, in the 50s 10.7%, in the 60s 15.2%, in the 70s 26.5% and in the 80s the incidence was 36.6%. The prevalence of symptomatic tears was 34.7% and  65.3% of all tears were in asymptomatic individuals. In the 50s one-half of all tears were asymptomatic whereas over the age of 60 two-third of the tears were asymptomatic.In this study the incidence of rotator cuff tears was 22.1% and the incidence increased with age. They also found that asymptomatic tears were  twice as common as symptomatic tear.
Asymptomatic tears can become symptomatic and can show anatomical deterioration with time (7 and 8).

Etiology of rotator cuff tears

Seventy five percent of the rotator cuff tears are due to impingement syndrome, 15% due to shoulder instability (anterior or multidirectional) and 10% due to trauma (9). Rotator cuff tears are broadly classified into two i.e degenerative tears and traumatic tears. Traumatic tears are due to significant trauma and are rare. The most common cause of rotator cuff tears is degeneration of the tendons caused by both intrinsic and extrinsic factors (10).The proponents of the extrinsic theory (Neer, Bigliani and others) have attributed the tendon degeneration to anatomical factors such as downsloping acromion (Bigliani type 2 and type 3 acromion), acromial spur, os acromiale, acromioclavicular spur and lateral extension of acromion (10). The intrinsic factors responsible for degenerative tears include ‘degenerative-microtrauma’, collagen thinning and disorganization, hyaline and myxoid degeneration, vascular proliferation and fatty infiltration (10). Other intrinsic factors responsible include ‘oxidative stress’ in the local environment and poor cuff vascularity(10).
Park et al (11) in a study involving a general population with atraumatic posterosuperior rotator cuff tears diagnosed with an MRI of the shoulder found that age, BMI, waist circumference, dominant-side involvement, manual labor, diabetes, hypertension, metabolic syndrome, ipsilateral carpal tunnel syndrome, HDL, and hypo-HDLemia were significant independent factors associated with development of posterosuperior rotator cuff tears.

Treatment of rotator cuff tears

Literature on the outcome of treatment of partial rotator cuff tears is sparse. However the treatment of partial tears is similar to the treatment for complete rotator cuff tears (12).

Conservative treatment

About one third of rotator cuff tears are symptomatic and the other two third are asymptomatic. Ninety nine percent of the patients with symptomatic tears present with pain (13).The severity of pain has no correlation with the severity of the rotator cuff tear (14). Inflammation of the shoulder seems to be the main cause of pain in patients with rotator cuff tears. The inflammation and pain often settles with NSAIDs and intra-articular steroid injections.
The reported successful outcome of conservative treatment of complete tears of the rotator cuff varies widely from 33% (15) to 82% (16). Itoi and Tabata (16) reported the outcome of conservative treatment of complete rotator cuff tears in 62 shoulders (54 patients) at an average follow up of 3.4 years. They found good to excellent outcome, as measured by the modified Wolfgang criteria, in 82% of the patients. The outcome was good in patients who had ‘well preserved motion and strength’ at the beginning of treatment. Unsatisfactory outcome was seen in patients who had limited motion and muscle weakness at the beginning of treatment.
Minagawa et al (17) reported good or excellent results in 75% of 100 patients (102 shoulders) with complete tears of the rotator cuff who were treated conservative. The average follow up was 32 (12 to 48 months). Fifty percent had no pain and 40% had mild pain which did not require medication.
The Moon shoulder group did a multicentre prospective cohort study (18)  to assess the effectiveness of physical therapy for treatment of atraumatic complete tears of the rotator cuff. The patients were initially instructed by physical therapist and then they continued their therapy at home. Supervised therapy was need only once a week. The patient were given an option for surgery if they were not better at any time during the treatment. If the patient opted for surgery than the conservative treatment was considered a failure. At 6 weeks follow up the success rate of conservative treatment was 91%, at 12 weeks it was 85%, at 1 year 79% and at 2 years the success rate of conservative treatment was 74%. They found that if the patient does not opt for surgery in the first 6 weeks he is unlikely to opt for surgery after that.
Kijima et al (19) published the 13 years follow up results of a prospective cohort of 103 shoulders with rotator cuff tear who were treated conservatively. The found that 90% of the patients had no or very little pain and 70% had no limitation of activities of daily living.
Lee et al (20 ) compared the effectiveness of conservative treatment with arthroscopic  repair for rotator cuff tears. They found that at one year follow up, conservative treatment is as effective as surgical repair in patients, with medium sized rotator cuff tears, who were  50 years of age or older.
From these studies it is clear that conservative treatment for complete tears of the rotator cuff is successful in 74% to 82% of the patients. Kuhn in 2009 (21) did a systematic review of the literature to evaluate the effectiveness of exercise in the treatment rotator cuff impingement. They found that ‘exercise has statistically and clinically significant effects on pain reduction and improving function, but not on range of motion or strength’. According to the review ‘manual therapy augments the effects of exercise, yet supervised exercise was not different than home exercise programs’.
Despite these successes of conservative treatment, a cochrane review (22) of manual therapy and exercise for treatment of rotator cuff disease paints a very different picture. The authors of the review included 60 trials in the study. There was only one trial comparing manual therapy and exercise with placebo. There was no clinically important difference between the two groups. They also found that there was low quality evidence to show that the’ effects of manual therapy and exercise may be similar to those of glucocorticoid injection and arthroscopic subacromial decompression’. The incidence of adverse events were more frequent with manual therapy and exercise as compared with placebo but the adverse events but mild in nature.
There is also no good quality evidence to support the use of electrotherapy modalities  for the treatment of rotator cuff disease (23).

Surgical treatment

Anecdotal evidence suggests that there is misplaced belief that all ligament and tendon tears must be repaired. Despite the popularity of such beliefs, literature on indications for repair of rotator cuff tears is sparse.
 The indications for surgery for atraumatic rotator cuff tears have not yet been defined. Even the MOON shoulder group were unable, by consensus, to develop standard indications for surgery (14).
 In 2007 Oh et al (24) reviewed the literature to investigate factors that influence decision making when patients present with full thickness rotator cuff tears. They looked at how ‘demographic variables, duration of symptoms, timing of surgery, physical examination findings, and size of tear’ affect outcome and indications for surgery. They found that muscle weakness and substantial functional disability maybe an indication for early surgical intervention. There was no clear link between demographic variables and treatment outcome. Although there have been reports of poor outcome of surgery in older patients, the authors did not find evidence to support such a belief. There is evidence in literature to suggest that the outcome of treatment is poorer in patients who have pending worker’s compensation claims. The authors concluded by saying that further research is needed to clearly define the indications for surgery in patients with complete tears of the rotator cuff.
Baysal et al (25) reported good outcome of repair of rotator cuff tears using a mini open technique. They reported improved shoulder function and health-related quality of life upto 5 years postoperatively. Ninety six percent of the patients were satisfied or very satisfied with the outcome of the surgery and 78% returned to their previous job within a year. The size of the tear and age of the patient did not affect the range of motion or the health-related quality of life.
There is apparently no difference in the outcome when comparing arthroscopic versus open repairs (26) and arthroscopic versus mini open repairs (27). Although good outcome of surgery is reported by many authors, the high complication rate and high rerupture rates are often not highlighted. Mansat et al (28) reported a 38% complication rate in patients undergoing rotator cuff repair. Sixteen percent of the patients had major complications affected the functional outcome. Some of the complications reported included frozen shoulder, deep infection and dislocations.
Brislin et al (29) reported a 10.6% incidence of complications after arthroscopic rotator cuff repair. Some of the complications reported included, ‘shoulder stiffness, failure of healing, infection, reflex sympathetic dystrophy, deep venous thrombosis, and death’. The complications are apparently similar to that with open repair of the rotator cuff.
Re-rupture rates of between 13% to 68% have been reported after repair of the rotator cuff  but interestingly patients suffering re-ruptures have significant improvement in pain and function (30). The re-rupture rates as detected by MRI vary between 20% to 39% and in patients with large tears the re-rupture rates at 2 years vary between 41% to 94% (29). The outcome of revision surgery after re-rupture is not as good as for primary repair. Djurasovic et al (31) reported excellent to satisfactory results in 69% of patients who had revision surgery. Despite structural failure of rotator cuff tears and complications, repairs of the rotator cuff do reduce pain, significantly improve function and strength (32).
Coghlan et al (33) did a systematic review of the literature for the Cochrane group, to review the effectiveness and safety of surgery for rotator cuff disease. They included 14 RCTs (829 participants) which compared surgical intervention to placebo, to no treatment or to any other treatment. They concluded that all the trials were ‘susceptible to bias’ and that they ‘cannot draw firm conclusions about the effectiveness or safety of surgery for rotator cuff disease’. There found that there was "Silver" level evidence from three trials ‘that there are no significant differences in outcome between open or arthroscopic subacromial decompression and active non-operative treatment for impingement’.
More recently there have been two prospective randomized studies which compared surgical and conservative treatments for rotator cuff tears and they found that there was no clinically significant difference in outcome between the two groups (34 and 35).
Chalmers et al [36] in 2018 carried out a systematic review of the intermediate to long-term (minimum 5-year) outcome of operative rotator cuff repair and no repair of rotator cuff injuries. The review included 29 studies with 1,583 patients. They compared patient-based outcomes, future surgical intervention, future tear progression or recurrence, and tear size in the two groups.
They found that there was no differences between rotator cuff repair and no repair with respect to strength and range of motion. Rotator cuff repair did not improve outcomes as measured with the Constant score even after adjustment for age, sex, duration of follow-up, and tear size. The rotator cuff repair appears to protect the shoulder from the need for future operative intervention but it does not, however, decrease the likelihood of sustaining a future tear. Rotator cuff repair may not alter natural history rotator cuff pathology.
Recurrent tears after rotator cuff repair are common and the treatment for these recurrent tears vary between conservative and open or arthroscopic revisions. Lädermann et al (37) in 2015 carried out systematic review of the management of failed rotator cuff repairs. They found that the mid to long-term outcome of patients treated conservatively was acceptable and a
persistent defect is usually well-tolerated and only occasionally will this defect require subsequent surgery. Hence conservative treatment can be recommended in most patients especially in patients with posterosuperior involvement and poor preoperative range of motion. In young patients with a repairable lesion, a 3 tendon tear, and in those with involvement of the subscapularis revision surgery may be necessary.

Conclusions

The rotator cuff comprising of the supraspinatus, infraspinatus, teres minor and the subscapularis muscles produce abduction and rotatory forces, stabilize the humeral head in the glenoid, stabilize the capsule and also provide muscular balance around the glenohumeral joint. The rotator cuff frequently tears due impingement syndrome (75%), shoulder instability(15) or trauma (10%). Non traumatic tears are asymptomatic in two third of the individuals and only symptomatic in about a third of the individuals. The prevalence of rotator cuff tears increase with age. The severity of symptoms does not correlate with severity of the cuff tear.
Rotator cuff tears which present with pain are commonly treated conservatively with NSAIDs, intra-articular steroids and physical therapy. Conservative treatment is successful in about 70% to 90% of the individuals. The evidence in support of physical therapy as a mode of treatment remains weak.
 Though there are many reports of successful treatment of symptomatic rotator cuff tears with surgery, the evidence to support the use of surgery for rotator cuff tears remains weak. Surgery can be associated high complication rate with some of them serious. Following surgery rerupture rate can be high.
 Recent studies show that the outcome of conservative treatment of cuff tears is clinically not significantly different from that of surgical treatment. Since the outcome of conservative and surgical treatment is similar, then logically conservative treatment should be the treatment of choice for symptomatic rotator cuff tears.

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