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  • Writer's picturePaul Monaro

Frozen Shoulder - Literature Review

As a follow-up on my article ‘Hydrodilatation’ for frozen shoulder, I have completed a basic review of the relevant up to date literature.


Definition Adhesive capsulitis, better known as frozen shoulder (FS) is characterised by the spontaneous onset of shoulder pain, and progressive reduction in both active and passive range of motion in at least two directions (3,5,10). The most significant loss of movement is in external rotation (10). While this is the accepted definition, some experts also describe ‘global restriction’, with loss of range in every direction. In reality, patients with true FS have global restriction. Loss of range in only two directions could be due to other conditions, including localised capsulitis. The condition is often over-diagnosed. A 1991 arthroscopic study found that of 150 patients referred with a diagnosis of FS, only 37 had ‘true’ adhesive capsulitis (15). Under-diagnosis is also common, particularly in the early stages when pain is a greater feature than stiffness, and the condition appears more like “subacromial impingement” or “rotator cuff tendinitis”. The pain in the early periods is often severe and disturbs sleep (3). FS typically affects people between the ages of 40 and 65 years (1,8,9,10,15), with younger cases reported but quite rare. In a systematic review covering 476 patients in four separate studies, the maximum age of FS sufferers was 56 years, and the minimum age was 47 years (10). In a 1991 arthroscopic study of 37 patients, the age ranges were between 40 & 70 (15). In a 2003 study with 106 subjects, the average age was 53 years (1).

The natural time course of the condition is recovery in one to three years (2), but it is not unknown for people to have ongoing restriction beyond this time-frame. Up to 40% to 50% of sufferers will have persistent symptoms past three years (8), and 15% persistent long-term disability (2,3,12). FS has three distinct phases (some authors describe four). Phase I is the inflammatory or ‘freezing’ stage, characterised by pain and progressive stiffness. This can last between two to nine months (3,7,10). Pain that disturbs sleep is common. Phase II is the frozen stage, with pain easing, but the patient being left with generalised restriction of movement in all directions. Pain is usually present at end of available range. This phase can last from four to twenty months (3,7). Phase III is the ‘thawing’ phase, with gradual recovery of movement. This can last from five to 26 months (3,7,10).


Incidence The literature consistently reports the incidence of FS as being between 2% to 5% in the general population (2,3,7,8,9,10,11,12). The incidence of people presenting to general practitioners in Holland was 2.4 per 1000 per year (3) and similarly around one in every 400 patients attending a GP in England (10). In patients with insulin dependent diabetes mellitus the prevalence increases to between 10% and 38% (7,8,11,12). Whether the side affected is related to handedness is unclear. In a study involving 106 patients, there were almost exactly equal numbers of left and right shoulders affected (1). However in a separate study involving 56 patients, Watson et al felt that the non-dominant shoulder was more likely to be affected (14). Neviaser et al agreed (9). Up to 34% of patients will experience FS in their opposite shoulder (8,9,11). Simultaneous involvement of both shoulders at the same time occurs in up to 14% of sufferers (8).


Associated Factors The cause of FS is still unclear, however it is known to be more common in certain individuals. While trauma has been suggested as a common precipitating event (7,9,15), it is possible that the trauma arises because the shoulder is already more vulnerable due to the disease. In my experience, trauma is rarely described by patients with true FS. Females are said to be affected slightly more than males (3,7,9), although across four reviewed studies, the incidence of female FS sufferers ranged from 38 to 67% (10). There is a strong association with diabetes, particularly type I . Delayed and less satisfactory recovery has also been reported in patients with diabetes (1,8). Other factors which have been implicated in contributing to FS include prolonged immobilisation (7,11), those being treated for breast cancer (9), those with thyroid disease (7,8,9,11), autoimmune diseases (7,9), scleroderma (11), Dupuytren’s contracture (11), and after myocardial infarction (7,8,9) and stroke (7,9).

Pathology The theory behind the onset of FS is that inflammation occurs (2,3), particularly in the axillary fold (3), and in the synovial membrane (5,15), followed by adhesions & fibrosis of the synovial lining and capsular ligaments (2). Patients with FS have been found to have both inflammatory cells and fibroblast cells indicating both an inflammatory process and fibrosis (8). The term adhesive capsulitis was coined in 1945 because of the suggestion of adhesions forming between the capsule and bone of the humeral head. However this is not generally found on arthroscopic investigation (5,15). “Patchy vascular synovial collections” were noted particularly around the subscapularis and biceps tendons (15), which may help to explain why external rotation range tends to be affected most (8). As a result of capsular fibrosis, the joint capsule contracts (8,9).


Examination The diagnosis of FS is a clinical one, and imaging is not usually required. Plain Xray and ultrasound are of no use for diagnosis of FS. Arthrography or MR arthrogram are the tests ordered when the diagnosis is unclear. This in rarely necessary. When the patient is examined, the findings will depend on the stage of the condition. In the early stages, there may be pain with certain movements, but movement may not be significantly restricted. As the disease becomes established, stiffness becomes the key feature, with pain present at end of available range. Typically, there is no weakness on muscle testing (9). If weakness is detected, this may be unrelated to the FS, and indicate the presence of a pre-existing rotator cuff injury. The examiner will assess a few key movements. In true FS, external rotation range will be affected more than other movements. The normal 70° to 90° range may be restricted to between 10° to 30°. Forward elevation may be restricted to between 90° to 120°, and will often be performed with excessive scapular elevation. Hand-behind-back range will also be moderately affected. To confirm ‘global restriction’, I also test horizontal adduction and external and internal rotation at 90° abduction. Management Many different treatments have been described for FS, and there is still no clear consensus regarding the effectiveness of many of these treatments. Complicating the picture is that the various stages of the disease may respond differently to the chosen treatment. In many of the studies reviewed, it was not always clear at what stage of FS the treatment was given.


Physiotherapy Physiotherapy as a stand-alone treatment is not generally effective during phase I or II of the disease (9). A gentle home exercise programme can be effective in relieving symptoms (8), and a physiotherapist can help with prescription of these exercises. In comparison with steroid injection alone, physiotherapy was found to be less effective (2,5,8). There is evidence that physiotherapy, when performed after intra-articular corticosteroid injection, is more effective than either intervention alone in improving pain and range of motion (2,5,9,14). The fact that range of motion improved more in the combination group suggests that physiotherapy is effective for FS when performed after steroid injection. Physiotherapy management approaches described in the literature include transcutaneous electrical nerve stimulation (5,8), joint mobilisation techniques (5,6,8), active and assisted range of motion exercises (5), gentle stretching (8), ice (5), scapular muscle control exercises (6), and isometric strengthening (5).


Cortisone Injection Injection of corticosteroid into the joint capsule has been claimed to provide quick pain reduction and to help restore movement. Some clinicians recommend it as the first-line treatment for FS in an attempt to settle symptoms quickly (2,6). Considering the anti-inflammatory effect, it is possible that the injections will be most effective if performed in the early, inflammatory stage of the condition (2,9). A 2011 review of the literature confirmed that improved pain and range of motion could be demonstrated in the short-term, but not the long-term (5,7). This has been a fairly consistent finding, and is not surprising considering that FS usually improves over time, even with no treatment. It is the short-term improvement in pain provides an attractive treatment option, particularly in the early stages when pain is a significant factor. In the short-term, it has been consistently shown to be effective in reducing pain (5,7), and some studies have found an improvement in range of motion compared to control groups (5,7). There is evidence that the combination of injection and physiotherapy is more effective than injection alone (2,5,6,9,14). In a systematic review covering 476 patients over four studies, the consensus was that steroid injections had a positive effect on the symptoms of FS in the short-term (10). Short-term was defined as 6 to 16 weeks. As the most painful phase of FS generally lasts less than 9 months, this may offer important symptomatic relief during a significant amount of this phase. It was suggested that up to three injections may be beneficial, and there was limited evidence that any more than this would provide additional benefit (10). In the long-term (6-12 months) physiotherapy was more beneficial than multiple injections (10). There is evidence that injections carried out under imaging (usually fluoroscopic control) are more effective, and that up to 60% of ‘blind’ injections are inaccurate (2,5,10).


Hydrodilatation This is performed under local anaesthesia, takes approximately 15 minutes, and the person goes home immediately afterwards. There is often transient pain during the procedure, and sometimes for a short time afterwards, but otherwise it is considered to be a safe procedure (1,3). Rest is advocated for two days, followed by return to normal activities (1). A home exercise programme &/or physiotherapy is often recommended as well. There is potential overlap between steroid injection and hydrodilitation that make it difficult to compare the two procedures. On the one hand, it has been argued that the benefits of hydrodilitation may be largely due to the anti-inflammatory effect of the steroid (2,13,14). On the other hand, it has been shown that a contracted capsule in a person with FS can rupture with only small volumes of injected fluid (13). The volume of the shoulder joint may be reduced to less than 10ml in FS (10), meaning that there may often be a combination effect of distension and anti-inflammatory. Interestingly, in a review of the literature into corticosteroid injection, it was found that the more effective studies may have been the ones where greater volumes were injected, even up to 40ml (2). In one study the injected volume of intra-articular steroid was 50ml (10). It is possible that even small doses may lead to capsular distension & / or rupture. Possible benefits of the procedure include disrupting adhesions within the joint (3), and an improvement in pain by reducing the stretch on pain receptors within the capsule (14). Repeat procedures are advocated when results are less than ideal (12). Good results have been reported, particularly for reducing pain. However, there are few quality studies of hydrodilatation for FS, and in most studies a control group was not used (1,12,13,14). Therefore, while encouraging results have been reported, it is impossible to determine if the results were due to the procedure, or due to time and natural recovery. There is no good evidence at this time that hydrodilatation offers superior results to other available treatments, particularly for helping with earlier return of range of motion (6,9). A study which compared hydrodilatation to cortisone injection alone found no significant differences between the two groups (13). The authors did not refer their subjects for physiotherapy post-intervention, and speculated that had they done so, this may have provided further benefit. In recalcitrant cases, where recovery is slow, or full movement is not regained over time, hydrodilatation may be an effective procedure to promote further recovery (6).


Oral Steroids According to an extensive literature review, there is moderate evidence for the benefit of oral steroids to help with the pain of FS, however there was no evidence that the benefit lasted beyond 6 weeks (4). Oral steroids were as effective as steroid injection in improving range, pain and subjective feelings of dysfunction (7). Due to their known side effects, injection would appear to be a better alternative.


Oral non-steroidal anti-inflammatory medication While these medications are commonly prescribed for FS, there is no good evidence that they provide any benefit other than temporary pain relief (6,9).


Manipulation under Anaesthesia This procedure is usually reserved for those cases where the shoulder remains restricted even after the expected recovery time. When compared to intra-articular steroid injection, both procedures were found to be equally effective (7). In a comparison with hydrodilatation, it was found to be less effective (7).


Arthroscopic release of the joint capsule There are no good quality studies examining the effectiveness of this technique (6).There are studies claiming benefits of this technique in recalcitrant cases (9).


References

1. Bell, S et al (2003). Hydrodilatation in the management of shoulder capsulitis. Australasian Radiology, 47, 247-251.

3. Buchbinder, R et al. (2008). Arthrographic distension for adhesive capsulitis (frozen shoulder). Cochrane Database Syst Rev. 2008 Jan 23;(1)

4. Buchbinder, R et al (2006). Oral steroids for adhesive capsulitis. Cochrane Database Syst Rev. 2006 Oct 18;(4)

5. Carette, S. et al (2003). Intraarticular corticosteroids, supervised physiotherapy, or a combination of the two in the treatment of adhesive capsulitis of the shoulder. Arthritis & Rheumatism, 48, 3, 829-838.

6. Favejee, M., et al (2011). Frozen shoulder: the effectiveness of conservative and surgical interventions--systematic review. BJSM, 45, 1, 49-56.

7. Griesser, M et al (2011). Adhesive capsulitis of the shoulder: a systematic review of the effectiveness of intra-articular corticosteroid injections. JBJS, 93-A, 18, 1727-1733.

8. Kelley, M et al (2009). Frozen shoulder: evidence and a proposed model guiding rehabilitation. JOSPT, 39, 2, 135-148.

9. Neviaser, A & Hannafin, J. (2010). Adhesive capsulitis: a review of current treatment. AJSM, 38, 11, 2346-2356.

11. Simpson, J & Budge, R (2004). Treatment of frozen shoulder using distension arthrography (hydrodilatation): a case series. Australasian Chiropractic & Osteopathy, 12, 1, 25-35.

12. Trehan, R. et al (2009). Is it worthwhile to offer repeat hydrodilatation for frozen shoulder after 6 weeks? The Int J of Clinical Prac., 64, 356-359.

13. Tveita, E. et al (2008). Hydrodilatation, corticosteroids and adhesive capsulitis: a randomized controlled trial. BMC Musculoskeletal Disorders, 9, 53.

14. Watson, L. et al (2007). Hydrodilatation (distension arthrograpy): a long-term clinical outcome series. BJSM, 41, 167-173.

15. Wiley, A (1991) Arthroscopic appearance of frozen shoulder. Arthroscopy, 7, 2, 128-143.


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