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About the Shoulder

By George A C Murrell

 

Overview Anatomy Diagnosis Examination Investigations Treatment Summary References

 

Overview

Disorders of the shoulder are common and often disabling. They affect all age groups but are particularly common in individuals who are active in sport, and in work or recreation that involves overhead activities. The clinical tests and imaging modalities used to diagnose shoulder pain have advanced significantly, as have methods to treat shoulder problems. Fortunately, we are moving out of the era of a "black box" for shoulder pain into an era where the condition can be diagnosed specifically and treated rapidly and effectively.

Major conditions affecting the shoulder

There are actually relatively few diagnoses to make when considering shoulder dysfunction. The shoulder can be too loose - (shoulder instability) or too stiff (frozen shoulder), the rotator cuff can dysfunction or there may be a fracture or arthritis. These disorders account for over 95% of all shoulder conditions (Table 1).

Table 1
Problem Structure Age group
Instability Labrum-capsule 17-30
Stiffness Capsule 40-60
Impingement Rotator cuff fatigue 30-60
Rotator cuff tear Rotator cuff especially supraspinatus 50+
AC joint pain AC joint cartilage 20-40
Arthritis Gleno-humeral joint cartilage 70+


Anatomy

For instability

The shoulder is the most mobile of all joints. Its bony anatomy is like a ball on a plate. The majority of the stability is provided by the labrum - a fibrocartilaginous rim that makes the plate a more saucer shaped structure - and the capsule, with its associated thickenings (glenohumeral ligaments). When the shoulder is forcibly dislocated, the capsule and labrum usually become detached from the glenoid neck creating a "Bankart lesion" (Figure 1). Treatment of traumatic instability is directed at repairing this lesion and the associated capsular laxity.

For Frozen Shoulder

For reasons we do not understand, in idiopathic adhesive capsulitis or frozen shoulder, the lining of the shoulder capsule becomes very vascular and painful, and the capsule becomes thickened, fibrotic and contracted. Loss of the normal laxity of the shoulder capsule results in a loss of gleno-humeral joint motion. Eventually, at an average of 2.5 years, this pathological process reverses and shoulder motion is restored - although not completely. Idiopathic adhesive capsulitis predominantly occurs in the 40-60 year old age group, is slightly more common in women (1.3:1) and in the left shoulder (1.3:1). Why it occurs in this age group and why it usually occurs spontaneously are undetermined7.

For Rotator Cuff

The most important muscles with respect to the shoulder are the rotator cuff. The rotator cuff is a set of four muscles (teres minor, infraspinatus, supraspinatus and subscapularis) that blend together and surround the humeral head to hold it within glenoid when performing overhead activities. Injury or fatigue of the rotator cuff results in the loss of this ability to hold the humeral head in the glenoid, and the larger deltoid muscle pulls the humeral head upwards causing "impingement" of the rotator cuff tendons to the acromion (Figure 2). It is likely that persistent impingement leads to ossification - spur formation of the coracoacromial ligament and a "hooked" acromion. The spur can lead to further impingement and wear to the supraspinatus tendon. Thickening of the subacromial bursa and tendinosis of supraspinatus occur as part of this impingement syndrome, which is also called subacromial bursitis.

Tears of supraspinatus are common and are associated with increasing age and apoptosis (programmed cell death)17 (http://www.ori.org.au/bonejoint/apoptosisjor.pdf). Management of rotator cuff dysfunction is aimed at reducing pain and restoring strength. Mechanical impingement may be relieved via an acromioplasty. An acromioplasty is usually performed arthroscopically using a burr to smooth off the "impinging" anterior 2-4 mm of the acromion. It may also be necessary to remove some of the under surface of the lateral acromion. There are good methods to reattach torn tendons, but none for reversing the ageing proeess. So reattachment is done less frequently with increasing age. Reattachment is performed more frequently when there is a good history of a traumatic episode to cause the tendon to rupture, and less frequently when there is an insidious onset of symptoms, or no symptoms.

Diagnosis

The first and most important step to take when managing shoulder dysfunction is to make a specific diagnosis (Table 2).

Table 2
Problem Age group Symptoms Diagnosis
Instability 17-30 Dislocations History of dislocation
Apprehension sign
Stiffness 40-60 Pain Loss of external rotation
Pain at night
Loss of movement
Impingement 30-60 Pain with overhead activities
Pain at night		 Impingement signs
Rotator cuff tear 50+ Pain with overhead activities
Pain at night
Inability to perform overhead activities		 Impingement signs
Weakness of external rotation
Weakness of supraspinatus
AC joint pain 20-40 Localised AC joint pain Paxinos sign
Arthritis 70+ Pain
Loss of movement		 Crepitus


Examination

Neck. Cervical nerve compression may cause shoulder pain. It is useful to rule out significant neck dysfunction by simply asking the patient to flex and extend their neck and look from one side to the other to see if this produces pain or if there is a restriction of movement.

Palpation. A useful test for AC joint pain is the Paxinos sign. Compress the acromio-clavicular joint together by placing one hand on the back of the acromion and one on the clavicle. A positive test occurs when pain is elicited via this manoeuvre. (Figure 6). In bicipital tendonitis the pain is often localised in the bicipital groove and it may be useful to palpate this area to reproduce the pain. Our research has shown that palpation in all other areas is not helpful in making a diagnosis8.

Stiffness. Stiffness can be ruled in or out as a cause of a shoulder problem early on in the exam by simply having the patient place their elbow by their side while the examiner gently externally rotates the arm (Figure 7). Pain does not usually limit external rotation as this manoeuvre is not very provocative. A block to external rotation, especially if it is rubbery or bony, implies either adhesive capsulitis or osteoarthritis. This can be confirmed by moving the arm in the other planes of movement. In adhesive capsulitis and osteoarthritis movements in all planes will be restricted. However, pay particular attention to the movement of the scapula, as in stiff shoulders the scapula will move with the humerus and give the false impression of movement at the glenohumeral joint.

Rotator cuff tear. Our research has identified three tests that are useful for diagnosing rotator cuff tear (Figure 8a-d):

  1. a positive impingement sign
  2. weakness in external rotation,
  3. weakness in supraspinatus8 (Figure 8a). The method for carrying out each of these tests is described in detail in our DVD.
If two are positive and the patient is over 60, there is a 98% chance of having a rotator cuff tear. If all three tests are positive the patient also has a 98% chance of having a rotator cuff tear. If two are positive and the patient is under 60, or if one is positive, then the examination is indeterminate. Perhaps most importantly, if none are positive a rotator cuff tear can be ruled out.

Specific signs

Impingement signs are useful to identify pain in the subacromial space (Figures 8c and 8d). For the external rotation impingement sign, the arm is abducted to 90 degrees and externally rotated. For internal rotation impingement, the arm is abducted to 90 degrees, brought across the body and then internally rotated. The aim of both manouvers is to impinge the rotator cuff and bursa underneath the acromion. A positive sign is when the patient has pain. They are not particularly helpful in making a specific diagnosis, however. Nearly any cause of shoulder pain can lead to a positive impingement sign.

The O'Brien sign9 is useful for identifying a superior labral (SLAP) lesion (Figure 9). The patient is asked to resist the examiner while holding the arm in the illustrated position (90° forward flexion, 10° adduction and the thumb pointing down). A positive test occurs when pain is elicited and that pain is reduced when retested with the patient's palm facing upwards.

Instability. If the practitioner is concerned about joint instability, there are a number of tests that can be performed12,13. The most useful is the sulcus sign - pulling the arm distally and looking for a sulcus underneath the acromion. A sulcus sign of two centimetres or more is an indicator of multidirectional instability16. It is an indication that there is gross laxity in the shoulder capsule. A negative sulcus sign does not rule out instability. The apprehension sign and its variants - augmentation and relocation signs - are very useful for confirming the diagnosis of traumatic anterior instability (Figure 10).

To carry out the apprehension test, the patient is placed supine and the arm is externally rotated. The test is most reliable when the patient expresses apprehension that the shoulder will "come out", rather than pain. There are several variants which are helpful: augmentation11 - increased apprehension when the humeral head is translated anteriorly; and relocation5 - decreased apprehension when the humeral head is translated posteriorly16.


Investigations (Table 3)

Table 3
Problem Imaging
Instability X-ray
Stiffness X-ray
Impingement X-ray
Ultrasound
Rotator cuff tear X-ray
Ultrasound
AC joint pain X-ray
Bone scan
Arthritis X-ray

A plain x-ray is important, especially if the practitioner is considering referral to a specialist. An x-ray will identify calcific tendonitis (Figure 11), a very painful condition that can be treated simply, if identified early. An x-ray will also rule arthritis in or out as a cause of symptoms. An x-ray can often be a guide for identifying rotator cuff dysfunction if there is spur formation on the acromion and the greater tuberosity.

Ultrasound is an easy and relatively inexpensive method of confirming or denying the presence of a rotator cuff tear. Shoulder ultrasound is, however, operator dependent, and centers that perform large volumes of ultrasound are more accurate than those that do not. Our research3 indicates a correlation coefficient of 0.7 for determining the size of tears (which is equivalent to MRI). Sensitivity and specificity of ultrasound for determining full thickness tears in experienced centers are 80-95%.

MRI is no better than ultrasound in identifying the presence or size of rotator cuff tears3 but is helpful when evaluating suprascapular nerve dysfunction. It can identify a ganglion compressing the suprascapular nerve in the spino-glenoid notch (Figure 12).

Bone scan is helpful for diagnosing AC joint pain14. X-rays are less helpful in predicting pain at the AC joint.


Treatment (Table 4)

Table 4
Problem Non-operative Operative Treatment
Instability External rotation splint Surgical stabilisation
Stiffness Wait 2.5 years Arthroscopic capsular release
Impingement Corticosteroid injection Arthroscopic acromioplasty
Rotator cuff tear   Surgical repair
AC joint pain Corticosteroid injection Distal clavicle excision
Arthritis NSAIDs Total shoulder replacement

Impingement syndrome, subacromial bursitis.

  1. Avoid overhead activities.
  2. A single injection of corticosteroid and local anaesthetic into the subacromial space (Figure 13). The position of insertion of the needle is 1 cm medial and 1 cm inferior to the postero-lateral corner of the acromion. The needle should be directed upwards towards the anterior edge of the acromion. Redirect the needle downwards if it hits the bone or upwards if it hits tendon. The solution for injection should include a corticosteroid (eg 1 ml of Depo-Medrol 40 mg/ml) and 5-10 ml of local anaesthetic (eg 1% lidocaine).
  3. Once the pain has settled down, usually at 3-4 weeks, institute a rehabilitation exercise regime focussing on external rotation power and endurance.
  4. If non-operative measures fail, then referral for arthroscopic acromioplasty. Our experience is that the first injection of corticosteroid is the most helpful, and that the response from subsequent injections reduces by 50% on each further injection. I would not recommend more than three injections of corticosteroid to a given area.
Calcific tendonitis. If identified early, the calcific material within supraspinatus can be aspirated under ultrasound guidance. This can be perfomed by a radiologist. No analgesia is usually necessary. Shockwave therapy (lithotripsy) may be used to disrupt more mature calcific lesions. The success of each of these procedures is directly proportional to the ability to remove the calcific material. In other words if the calcific material is removed, then the success rate is high and often very gratifying for the patient. If the material cannot be removed, then pain usually persists.

Rotator cuff tear. If the tear is acute, particularly in a young (< 60 year old) individual, and is full thickness, the standard treatment is a rotator cuff repair. The procedure has an over 90% success rate at reducing pain. However, full supraspinatus power is not usually restored and follow-up imaging studies often reveal persistent or recurrent defects in the tendon. Gains from surgery become most obvious between 3 and 6 months and plateau at 2 years. Partial thickness rotator cuff tears (less than 50% of the thickness of the tendon) are generally treated as per impingement syndrome. In the elderly (over 75), particularly if there is a chronic, large tear, repair may not be feasible and is more likely to re-rupture. A true A-P x-ray is a useful screening tool to determine if the tear is chronic. If the humeral head has migrated proximally and is articulating under the acromion (Figure 14), then it is likely the tear is chronic and any remaining tendon worn away.

Cuff tear arthropathy. Chronic rotator cuff tears sometimes lead to secondary glenohumeral joint arthritis - a syndrome called "cuff tear arthropathy" (Figure 14). Treatment of "cuff tear arthropathy" is not straightforward; however, replacing the humeral head with a metal prosthesis can be helpful in reducing pain.

Biceps rupture. Rupture of the long head of biceps in the bicipital groove can be treated with benign neglect, ie return to full activities as soon as pain persists. The only significant adverse sequelae is the cosmetic deformity of a "pop-eye" sign. Elbow flexion strength is rarely affected, however patients may loose power of supination (eg stuing a screwdriver). Distal biceps rupture in a young individual is more problematic and early surgical repair should be considered.

Arthritis. The treatment for arthritis is the same as those for other joints. Early on, non-steroidal anti-inflammatory agents are helpful. In the later stages a shoulder replacement is a very effective means of improving pain. As arthritis is less frequent in the shoulder than in the hip or knee, total shoulder replacement is performed less frequently than hip and knee replacements. Most shoulder surgeons would perform between 10 and 20 shoulder replacements a year. Fortunately the rate of revision is very low. The one exception being for cuff deficient shoulders. If a glenoid component is placed in a rotator cuff deficient shoulder the abnormal upward forces placed on the glenoid will induce it to "rock free". For this reason, hemiarthroplasties - only the humeral component - are usually used for rotator cuff deficient shoulders.

Frozen shoulder. The natural history of idiopathic adhesive capsulitis is that it will resolve on its own over two-and-a-half years. One option is, therefore, to wait it out as it will always get better. Non-interventional modalities including physiotherapy, drugs and injections have not been shown to improve the outcome of frozen shoulder1. An alternative approach is an arthroscopic capsular release. This is a procedure where the thickened capsule is divided under direct vision in a circumferential manner around the glenoid. This effective procedure is often performed under interscalene block as a day-case. It restores range of motion and removes pain immediately. It is important to combine the surgery with an aggressive post-operative rehabilitation program to maintain motion2.

AC joint. Arthritis of the AC joint can be effectively treated with a single local anaesthetic - corticosteroid injection into the joint, usually by a radiologist under x/ray control. If this works, then recurs, then the current surgical procedure available is a distal clavicle excision. Although reasonably widely performed, the results of this procedure have been rarely reported, suggesting that outcomes may not be optimal.

Instability. The patient presenting in middle age with a shoulder dislocation should be carefully evaluated for a tear or an avulsion fracture of the rotator cuff. Test for supraspinatus weakness, perform an xray and if concerned an ultrasound. If there are no tendon injuries or fractures, patients who are advancing in age, particularly those over 40 should be managed non-operatively as the shoulder becomes tighter in this age group and recurrence rates are low, when treated conservatively.

In younger age groups (17-40 years) recurrence rates are high. A newly identified principle of non-operative treatment of shoulder instability is to avoid using a sling6. Placing the arm in internal rotation will open up the Bankart lesion and increase recurrence rates4. If immobilization is to be considered, then the arm should be placed in external rotation in an external rotation pillow or brace (http://www.ori.org.au/bonejoint/shoulder/ssfd.htm) as this will force the Bankart lesion to re-appose to the glenoid neck6.

The ease and technology for repairing Bankart lesions has advanced significantly. The detached labrum can be reattached using suture anchors - often biodegradable harpoons that lodge in bone with sutures attached that can be passed through the labrum and capsule to reattach it to the anterior and inferior glenoid margins. The procedure can be performed arthroscopically under local anaesthetic as a day case, with minimal morbidity (Figure 15).

Multi-directional instability. Multidirectional instability is a problem of capsular laxity, and is particularly prevalent in young girls. The first line management is a rehabilitation program focussing on scapular control and rotator cuff strengthening. The condition does improve with age. Sports that involve repetitive overhead activities (eg swimming) are more difficult for athletes with multidirectional instability. Surgical techniques to reduce the volume of the shoulder capsule (eg pants over vest plication) are well established, however, the results are not as successful as those for acute traumatic anterior instability.


Summary

Shoulder dysfunction is usually caused by the shoulder capsule being too tight or too loose, by the rotator cuff musculotendinous unit being damaged or fatigued and less frequently from damage to the articular cartilage of the glenohumeral joint or acromioclavicular joint.

AC joint pain is the one shoulder disorder where pain is localized. Stiffness can be confirmed by testing external rotation motion and looseness by an apprehension test. Rotator cuff function can be checked, by assessing power of external rotation and supraspinatus, and impingement signs.

X-rays are useful for diagnosing calcific tendonitis, glenohumeral joint arthritis and cuff-tear arthropathy. Ultrasound is used to confirm a rotator cuff tear. A single corticosteroid injection in the relevant location is a useful first-line treatment for AC joint pain and impingement.

Persistent impingement, instability, stiffness and many rotator cuff tears can be restored effectively with minimally invasive arthroscopic surgery. Shoulder replacement is effective for treating severe gleno-humeral joint arthritis.


References

  1. Bhargav D, Murrell GAC: Shoulder stiffness: diagnosis. Aust Family Physician 33: 143-7, 2004

  2. Bhargav D, Murrell GAC: Shoulder stiffness: management. Aust Family Physician 33: 149-52, 2004

  3. Bryant L, Shnier R, Bryant C, Murrell GAC: A comparison of clinical estimation, ultrasonography, magnetic resonance imaging, and arthroscopy in determining the size of rotator cuff tears. J Shoulder Elbow Surg 11: 219-24, 2002

  4. Itoi E, Hatakeyama Y, Kido T, Sato T, Minagawa H, Wakabayashi I, Kobayashi M: A new method of immobilization after traumatic anterior dislocation of the shoulder: A preliminary study. J Shoulder Elbow Surg 12: 413-5, 2003

  5. Jobe FW, Kvitne RS, Giangarra CE: Shoulder pain in the overhand or throwing athlete. The relationship of anterior instability and rotator cuff impingement [published erratum appears in Orthop Rev 1989 Dec;18(12):1268]. Orthop Rev 18: 963-75, 1989

  6. Murrell GAC: Treatment of shoulder dislocation: is a sling appropriate? Medical Journal of Australia 179: 370-1, 2003

  7. Murrell GAC, Bhargav D: Medical and surgical manipulation of the shoulder capsule and labrum. APLAR J Rheum 2: 247-52, 1999

  8. Murrell GAC, Walton J: Diagnosis of rotator cuff tears. Lancet 357: 769-70, 2001

  9. O'Brien SJ, Pagnani MJ, Fealy S, McGlynn SR, Wilson JB: The active compression test: a new and effective test for diagnosing labral tears and acromioclavicular joint abnormality. Am J Sports Med 2: 610-43, 1999

  10. Paxinos A, Rutten S, Walton JR, Murrell GAC. Temporal outcomes of arthroscopic stabilization of superior labral (SLAP) tears with biodredable tac. in 27th Annual Meeting American Orthopaedic Society for Sports Medicine. 2001. Keystone, Colarado.: pp

  11. Silliman JF, Hawkins RJ: Current concepts and recent advances in the athlete's shoulder. Clin Sports Med 10: 693-705, 1991

  12. Tzannes A, Murrell GAC: Clinical examination of the unstable shoulder. Sports Medicine 32: 1-11, 2002

  13. Tzannes A, Paxinos A, Callanan M, Murrell GAC: An assessment of the inter-examiner reliability of tests for shoulder instability. J Shoulder Elbow Surg 13: 18-23, 2004

  14. Walton J, Paxinos A, Mahajan S, Marshall J, Bryant C, Shnier R, Quinn R, Murrell GAC: Diagnostic values of tests for acromioclavicular joint pain. J Bone Joint Surgery (Am) 86: 807-12, 2004

  15. Walton J, Paxinos A, Tzannes A, Callanan M, Hayes K, Murrell GAC: The unstable shoulder in the adolescent athlete. Am J Sports Med 30: 758-67, 2002

  16. Walton J, Tzannes A, Murrell GAC. The predictive value of clinical tests for shoulder instability. in 47th Annual Meeting Orthopaedic Research Society. 2001. San Francisco: Orthopaedic Research Society, pp 0288

  17. Yuan J, Murrell GAC, Wei A-Q, Wang M-X: Apoptosis in rotator cuff tendonopathy. J Orthop Res 20: 1372-9, 2002
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