Treatment of persistent shoulder pain

                              Dr. KS Dhillon

Persistent shoulder pain is a common clinical problem and it is often associated with limited range of motion and decreased function [1,2]. An estimated 20 percent of the population will suffer shoulder pain during their lifetime [3]. Shoulder pain is second only to low back pain in patients seeking care for musculoskeletal ailments. There are several causes of such persistent pain and these include glenohumeral osteoarthritis, rotator cuff tears, subacromial impingement, tendinitis, adhesive capsulitis, and subacromial bursitis [4].

Damage or dysfunction affecting one component of the shoulder can lead to secondary pathological changes, in other areas of the shoulder leading to persistent pain [4,5]. A rotator cuff tear, for example, can lead to mechanical and degenerative changes in the glenohumeral joint and that can result in symptomatology [4,6,7].

Effective treatment depends on an accurate diagnosis of the cause of the shoulder pain. The causes of the shoulder pain can include the following diagnosis, rotator cuff disorders, adhesive capsulitis, acromioclavicular osteoarthritis, glenohumeral osteoarthritis, and shoulder instability.

The initial treatment involves activity modification and analgesic medications. If no improvement occurs or if the initial presentation is very severe, a trial of physical therapy that focuses on the particular diagnosis is indicated. 

Combined local anesthetic and steroid injections can be used alone or in combination with physical therapy. The site of the injection depends on the diagnosis and it can be into the shoulder joint, subacromial space, or into the acromioclavicular joint. Injections into the glenohumeral joint are usually done under fluoroscopic guidance. 

Treatment Overview

A systematic review of randomised controlled trials of interventions for painful shoulder showed little evidence for or against the most common treatments of chronic shoulder disorders [8]. This is mainly because of a lack of well-designed clinical trials. Nevertheless, most patients with chronic shoulder disorders can initially be treated conservatively with a combination of activity modification, physical therapy, medications, and steroid injections if necessary.

The outcome of this approach is satisfactory in majority of the patients [9,10].  

Activity Modification

A simple treatment for reducing shoulder pain is activity modification.  Recommendations are based on the underlying diagnosis. Avoidance or reduction of overhead activity is the mainstay of treatment for patients with glenohumeral osteoarthritis, rotator cuff pathology, and adhesive capsulitis because this avoids the painful arc between 60 to 120 degrees. Heavy loading of the shoulder should be avoided in patients with glenohumeral osteoarthritis to reduce pain. Certain activities such as bench pressing, kayaking, and overhead throwing should be avoided in patients with an unstable shoulder. In patients with acromioclavicular osteoarthritis cross-body shoulder adduction, such as the motion performed in the golf swing or weight lifting, should be limited to prevent pain. 

Medications

Pain control with the use of nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, or short-term opiate medication is imperative to allow for the progression of treatment. Although NSAIDs are widely used to treat pain, there is no conclusive evidence to support the use of NSAIDs over simple analgesia in the treatment of chronic shoulder pain [11]. The risks and benefits of each class of drugs should be considered before its use [4].

Physical Therapy

Physical therapy includes several types of treatment. There are several modalities to alleviate pain such as heat and ice, ultrasound, hyperthermia, and iontophoresis. Stretching and strengthening exercises improves overall shoulder function and relieves pain. 

The type of physical therapy will depend on the underlying etiology. Little evidence exists for the use of these therapeutic modalities alone [12]. A Cochrane review showed that strengthening and stretching exercises provide improved short-term recovery and long-term function in patients with rotator cuff disease [12].

Calis et al [13] carried out a study to compare the efficacy of sodium hyaluronate injection with the most common treatment methods, such as intraarticular steroid injection, and physical therapy modalities in patients with adhesive capsulitis. They found that physical therapy provided the best results as compared to other treatment modalities.

For success of physical therapy, the underlying diagnosis must be known and the patient must actively participate in the rehabilitation process on a daily basis.

Injections

Corticosteroid injections combined with a local anesthetic are administered if patients have a poor response to initial treatment for chronic shoulder disorders. The injection has to be directed toward the area of underlying pathology, such as the subacromial space, glenohumeral joint, or acromioclavicular joint. 

The role of subacromial injection for rotator cuff disease is an area of controversy as well as active research. There are two systematic reviews that found little evidence to support or refute the use of subacromial injections and there are two systematic reviews that found it to be beneficial for rotator cuff tendinitis and shoulder pain. There is another review that suggested a possible small benefit [14-18]. 

There are several studies that have found subacromial injections to be beneficial,  for short-term decrease in pain and increase in function [17,18,19,20].

A study by Koh KH [21] to assess the efficacy and safety of corticosteroid injections for adhesive capsulitis showed that corticosteroid injection is superior to placebo and physiotherapy in the short-term (up to 12 weeks), but there is no difference in outcomes between corticosteroid injection and oral nonsteroidal anti-inflammatory drugs at 24 weeks.

A systematic review of corticosteroid injections into the shoulder for adhesive capsulitis by Shah N [22] provided convincing evidence based on 3 high-quality studies in which use of multiple corticosteroid injections had beneficial effect on pain reduction, improved function and increased range of movements.

According to the American Academy of Orthopedic Surgeons (AAOS), there is moderate evidence to support the use of a single injection of steroids with local anesthetic for short-term pain relief and improvement in shoulder function in patients with rotator cuff tears [23].

In patients with adhesive capsulitis, intra-articular injections of steroids decrease pain and increase function, particularly in combination with physical therapy for stretching [18,24].

The AAOS does not recommend the use of intra-articular steroid injections for glenohumeral osteoarthritis [25]. The AAOS has no recommendation for use of hyaluronic acid injection in patients with glenohumeral osteoarthritis [4]. 

The AAOS endorses the use of steroid injection into the acromioclavicular joint for osteoarthritis despite few studies demonstrating its effectiveness [25]. 

Surgery

Most patients respond to conservative treatment for shoulder pain. Those patients who do not respond to conservative treatment, surgical treatment may be required. Patients with continued instability or disabling pain that is not responsive to conservative treatment may require surgical treatment [4,25,26]. 

Treatment of Specific Conditions

1. Acromioclavicular osteoarthritis

Acromioclavicular osteoarthritis is a common condition and it can produce chronic shoulder pain. It can be associated with subacromial impingement syndrome of the shoulder. The mainstay of treatment is pain control and activity modification [25]. Pain control may be obtained with the use of NSAIDs or other analgesics. If there is a failure to obtain pain relief with analgesics, corticosteroid injections can be used. Corticosteroids are usually effective in short-term pain control for more severe cases [27]. Failure to improve or maintain function with conservative treatment may warrant surgical treatment. Resection of the distal clavicle is often effective in relieving the pain symptoms [28,29]. 

2. Adhesive capsulitis

The treatment of adhesive capsulitis can be challenging. Long-term follow-up studies show that adhesive capsulitis resolves spontaneously over one to two years without intervention [25,30]. The aim of treatment is to decrease the duration of symptoms. The treatment essentially involves activity modification to decrease pain, anti-inflammatory or analgesic medications, and a physical therapy regimen for stretching and mobilizing the shoulder, both with the therapist and at home.

In the event of no progress or slow progress after six weeks, an intra-articular steroid injection can be given. An intra-articular injection of corticosteroid has shown short-term benefits in reducing pain and disability at the six-week follow-up [31]. The accuracy of injection is improved with the use of a fluoroscope. If a dye is injected it can confirm the position of the needle. The dye will also provide an arthrogram, that can rule out other concomitant pathologies such as a rotator cuff tear. The need for surgical intervention is rare. Arthroscopic capsular release is usually not necessary. A manipulation of the shoulder under anesthesia may sometimes be required.

3. Rotator cuff disorders

Shoulder pain due to rotator cuff pathology can usually be treated successfully with conservative modalities [32,33]. The conservative treatment involves activity modification, physical therapy, and the use of anti-inflammatory or analgesic medications. The aim of physical therapy is to improve the strength, range of motion, and proprioception of the shoulder. If there is no improvement after several weeks, a subacromial corticosteroid injection may provide significant pain control that will allow range of motion to improve with physical therapy [34]. 

If the clinical assessment demonstrates that the rotator cuff is intact, a three to six-month trial of conservative treatment is usually adequate. For small rotator cuff tears also, a six to 12 weeks of nonoperative treatment is reasonable. Large retracted rotator cuff tears, sometimes seen in patients with a history of trauma or dislocation often need surgical intervention. These patients usually present with severe pain and significant supraspinatus, infraspinatus, and subscapularis weakness. Surgical treatment can be open, mini-open, or arthroscopic decompression and rotator cuff repair.

4. Glenohumeral osteoarthritis

Glenohumeral osteoarthritis is not a common condition and is a less common source of chronic shoulder pain. Glenohumeral osteoarthritis can produce significant pain and disability. The aim of treatment is to maintain overall function with adequate pain control. Pain control is obtained with anti-inflammatory or analgesic medications. If pain, however, is not adequately controlled, an intra-articular steroid injection may be given. There is, however, little evidence to support the use of steroid injection, and its use is not endorsed by the AAOS [25].

Physical therapy can help maintain shoulder function. Patients with shoulder osteoarthritis often have joint incongruity and aggressive attempts at increasing the range of motion can be counterproductive. The aim should be to maintain a functional, pain-free range of motion of the shoulder. 

In patients with advanced osteoarthritis who have severe disability, surgery may be required. Capsular release and arthroscopic debridement, hemiarthroplasty, and total shoulder arthroplasty are surgical options available [35]. There are, however,  no clinical trials or systematic reviews comparing conservative versus surgical treatment outcomes.

5. Glenohumeral joint instability

Glenohumeral instability leading to chronic shoulder pain may be related to an old dislocation of the shoulder or repetitive overuse in a young athlete with some ligamentous laxity. The initial treatment should focus on activity modification and an aggressive muscle strengthening program. Strengthening of the rotator cuff muscle and scapular stabilizer muscles can be very useful, particularly for athletes with traumatic instability of the shoulder [36]. Surgery has to be carried out if there is a failure to improve with conservative treatment or there is recurrent dislocation or subluxation. 

Sodium hyaluronate for treatment of shoulder pain

The role of hyaluronate (HA) treatment for chronic painful shoulder has not yet been elucidated although HA injections are commonly used. There is little evidence to support their use. None of the published studies have proven undeniable efficacy of HA for the treatment of chronic shoulder pain.

Saito et al [37] carried out a meta-analysis of randomized controlled trials that compared the efficacy of HA injections with that of placebo. The authors concluded that the meta-analysis provided evidence that HA injections are a valuable alternative to other conservative methods for treatment of chronic shoulder pain. The authors admitted that there were limitations of this meta-analysis. They said that only a few conclusions could be drawn from the meta-analysis because of the relatively small number of studies included. They empahasized the need of additional investigations on the use of HA injections for shoulder pain.

Furthermore, in the article by Saito et al, the term periarthrities was used and a precise diagnosis was not made and the exact cause of shoulder pain was not established. Furthermore the HA injection was given at different sites. These facts makes the study less effective. The diagnosis and treatment should be more homogenous to provide potentially useful information for therapeutic recommendations.

Blaine et al [38] carried out a randomized, controlled trial to study the efficacy of sodium hyaluronate in the treatment of persistent shoulder pain. This was a multicentre study. The study included 660 randomized patients with moderate to severe shoulder pain that was refractory to standard treatment. They had three treatment groups namely the three-injection hyaluronate group, five-injection hyaluronate group, and phosphate-buffered saline solution group.

The majority (about 60%) of the patients in each treatment group had a diagnosis of osteoarthritis as the etiology of shoulder pain. Two thirds of these patients had concurrent shoulder abnormalities such as a partial or complete rotator cuff tear and/or adhesive capsulitis. The authors found that although the primary end point of this study was not achieved, the overall findings, including secondary end points, indicate that sodium hyaluronate is effective and well tolerated for the treatment of osteoarthritis and persistent shoulder pain that is refractory to other standard nonoperative interventions. The patients were not followed beyond twenty-six weeks, it is unclear how long the clinical benefit would have been maintained in these patients. The lack of fluoroscopic guidance may be considered a limitation of the study.

There, however, were glaring conflicts of interest in this study. The authors received editorial support in the preparation of this manuscript that was funded by the study sponsor i.e the manufacturers of sodium hyaluronate.

Harris et al [39] carried out a systematic review to study the efficacy of intra-articular hyaluronate injections for the treatment of adhesive capsulitis. The systematic review showed that sodium hyaluronate injection into the glenohumeral joint significantly improves shoulder range-of-motion, constant scores, and pain at short-term follow-up following treatment of adhesive capsulitis. They also found that isolated intra-articular hyaluronate injection has equivalent outcomes as compared to intra-articular corticosteroid injection. The study also showed that the improvement in range-of-motion following isolated hyaluronate injection was greater than control; however, the difference was not significant. There were several limitations in this study and one of the significant limiting factor in this review was the very short-term follow-up duration.

Prognosis

The prognosis of chronic shoulder pain depends to a large extent on the underlying cause of the pain. Generally, the pain responds well to conservative treatment [40,41]. Symptoms of gradual onset, more severe pain at presentation and prolonged symptoms are associated with a worse outcome for protracted recovery [42,43]. Generally, the speed of recovery in patients with chronic shoulder pain is slow. There are two prospective studies involving patients with chronic shoulder pain that have shown complete recovery at one month in 23 percent of patients, and at 18 months in 59 percent of patients [9,10].

Conclusion

Persistent shoulder pain is a common clinical problem. An estimated 20 percent of the population will suffer shoulder pain during their lifetime There are several causes of such persistent pain and these include glenohumeral osteoarthritis, rotator cuff tears, subacromial impingement, tendinitis, adhesive capsulitis, and subacromial bursitis. 

Effective treatment depends on an accurate diagnosis of the cause of the shoulder pain. Most patients respond to conservative treatment that involves activity modification, analgesic medications, and physical therapy. Failure to respond to these treatment modalities would be an indication for steroid injections. HA injections have no established role in the treatment of chronic shoulder pain. Surgery is rarely indicated.

Generally, the prognosis is good in most patients. Most patients recover within one to 18 months.

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