The ‘3S’ approach

We suggest focusing on three key symptomatic questions: stability, stiffness and soreness. This will facilitate a systematic approach to the diagnosis and treatment of common causes of shoulder pain.

Question 1: Is the shoulder stable?

The stability of the shoulder depends on static constraints of the gleno-humeral articulation, the labrum and the glenohumeral ligaments of which the anterior (AGHL), middle (MGHL) and inferior (IGHL) portions serve different functions. Dynamic constraints include the rotator cuff muscles and proper interplay between the movements of the scapula and the thorax. The relative lack of bony stability makes the shoulder the most frequently dislocated joint. Four common forms of dislocation occur: anterior, posterior, inferior and multidirectional.

Anterior dislocation: The common history of injury involves the arm in abduction and external rotation while a force is directed from posterior to anterior. Patients report apprehension about reaching behind the head. Physical exam reveals increased anterior translation of the humeral head with the arm at side in slight abduction. A positive apprehension test in abduction and external rotation reflects incompetent labrum and IGHL.

Posterior dislocation: A muscle imbalance allows the subscapularis to overpower the other rotator cuff muscles, forcing the humeral head posteriorly. It’s less common than anterior injury, but can manifest during seizure or electric shock (including indwelling defibrillators) and can also occur secondary to trauma. The patient may report discomfort with internal rotation while reaching across the body, or inability to perform a bench press/push up manoeuvre. Clinical examination reveals a positive jerk test or posterior drawer sign.

Inferior dislocation: Although rare (0.5% of all cases) this injury can have up to 60% incidence of associated brachial plexus injury. Axillary arterial compression can also occur. Residual defects include a sulcus sign with inferior traction in the adducted arm.

Multidirectional instability: This presentation is usually atraumatic. Patients have a history of generalized ligamentous laxity. Symptoms of subluxation can be anterior or posterior with resulting inferior translation. This condition should prompt a survey for connective tissue disorders (e.g. Marfan’s, Elhers Danlos).

Evaluation and treatment

X-rays are helpful in obtaining the information to guide treatment. Typical baseline imaging requires a true anterior-posterior (AP) view in internal and external rotation, and an axillary lateral view. In an anterior dislocation, the IGHL complex, which serves as a “hammock” of stability, can be injured with the capsule-labrum complex (Bankart lesion) or with a bony avulsion (bony bankart) off the glenoid. The resultant dislocation can create an impaction defect in the humeral head (Hill-Sachs), which may need to be addressed surgically. Furthermore, the rotator cuff, which tends to be injured in patients above the age of 45 years, can be evaluated by imaging if a cuff tear is suspected. In posterior dislocations, injury to the posterior labrum-ligament complex can be seen. The bony defects (if present) are in the posterior glenoid and antero-superior humerus (reverse Hill-Sachs lesion).

Treatment of anterior dislocations includes orthopedic referral since many young patients have high risk of repeat dislocation. A pure uncomplicated first time dislocation may be managed non-operatively. Gradual rehabilitation is then initiated. But in young athletes under the age of 20, recurrence rate can be up to 90%, while those 20-40 years of age have a 60% recurrence rate. As the age increases to above 40 years, the incidence drops to 10%. Given the high recurrence rate and usual association with sporting activity, surgical treatment is often performed. Both arthroscopic and open techniques are available, with success rates of 85-94% and 90-95%, respectively.

Surgery can also address bony deficiencies with direct repair or filling in defects with bone and soft tissue transfers. Posterior dislocation is also addressed by re-tensioning the soft tissues and ligaments and addressing bony defects. Careful rehabilitation is key in assuring adequate time for the soft tissues to heal with the appropriate tension. Recurrence of 4-15% can occur in anterior procedures with more variable results in posterior treatments (7-50% recurrence).

Question 2: Is the shoulder stiff?

The commonest causes of stiffness in the shoulder are arthritis and “frozen shoulder.” Osteoarthritis (OA) can be primary or it may be secondary to trauma, chronic instability or previous surgery. The classic pattern of posterior wear of the glenoid and subluxation of the humerus results in contracture of the anterior capsule and subsequent limitation in external rotation. Patients often complain about activity-related pain, night pain and loss of function. Clinical exam may reveal a flat-looking anterior contour, limited active and passive range of motion, especially external rotation, crepitus, and pain with motion. X-ray imaging demonstrates osteophytes on the inferior humeral head, joint space narrowing and subchondral sclerosis. Axillary views can reveal glenoid erosion and help determine the type of surgical technique and implants. It’s vital to know the status of the rotator cuff. MR imaging can help to clarify this question. Rheumatoid arthritis (RA) tends to involve more bony destruction and higher incidence of rotator cuff (RTC) insufficiency.

Nonsurgical treatment involves physical therapy to preserve motion, NSAIDs, anti-rheumatic medications and prudent use of intra-articular corticosteroid injections.

If the patient has an intact cuff, no history of infection, a functioning deltoid and is neurovascularly intact, the standard treatment is a total shoulder arthroplasty (TSA), which has up to a 93% 10-year survival rate in patients with OA. Results are slightly inferior in patients with RA. Arthroscopy with debridement has limited benefits in this patient population. If the rotator cuff is insufficient, surgical evaluation is still warranted to determine if alternative implants, such as a reverse total shoulder prosthesis is warranted. Even when the glenoid bone and rotator cuff are severely deficient, a unique technique of hemiarthroplasty may provide good outcome.

Frozen shoulder typically presents as a stiff, painful shoulder in the setting of normal x-rays. Other causes of shoulder pain should be excluded. The syndrome occurs over three phases; the freezing phase, the frozen phase, and the thawing phase. Typically, pain only occurs in the first (freezing) phase. In this phase, treatment is directed towards pain control. Stretching and rehabilitation is reserved for the second and third phases where they have been shown to be effective. Surgery can be necessary in refractory cases but the majority of patients recover their range of motion by non-surgical means. The most severe cases of frozen shoulder can remain symptomatic for over 2 years.

Question 3: Is the shoulder sore?

Isolated shoulder pain is commonly due to rotator cuff and/or biceps pathology. The tendons could be inflamed, partially torn or completely torn. Most rotator cuff tears are a result of chronic degeneration. Acute tears tend to occur in the younger population age 40-60. The typical presentation includes pain with overhead activity, pain reaching behind the back and pain at night. Clinical exam may reveal:

• impingement signs
• pain with resisted abduction (using the empty can test or full can test) indicating supraspinatus weakness
• weak resisted external rotation (implicating infraspinatus and/or teres minor)
• positive Hornblower’s sign (implicating teres minor)
• inability to lift the back of the hand off the flat of the back (lift-off test) or positive belly press testing determines subscapularis function
• biceps tendonitis should also be verified.

Imaging should include true AP and axillary views. The humeral-acromial distance may be decreased to less than 7 mm if a tear is present. MR is considered the gold standard in characterizing the cuff tear and other intra-articular pathology. Ultrasound is accurate but may not provide as much information regarding the entire joint.

Initial treatment of partial-thickness cuff tears and tendonitis involves NSAIDs, judicious use of cortisone injections and physiotherapy. Full-thickness tears — and partial tears that fail conservative treatment — may benefit from surgery. The primary goal is pain relief. Arthroscopic and open procedures are available. The risk of infection is < 1% for both. Recent reports suggest that early treatment of large full thickness tears yields better overall outcomes. It’s been observed in MRI studies that injured muscle develops increasing amounts of fatty infiltrate, and this correlates with lower likelihood of an optimal outcome.

Final points

The myriad of potential etiologies in a symptomatic shoulder can overwhelm a clinical encounter. Ruling out the red flags of cancer, infection, fracture and neurological disorder is a vital first step in any assessment. That done, a simple approach based on the above questions should enable most shoulder pathology to be diagnosed and managed with accuracy and safety.

Further reading

1. Lieberman J. AAOS Comprehensive Orthopedic Review, American Academy of Orthopedic Surgeons, Rosemount, IL 2009.
2. Galatz, L. Orthopedic Knowledge Update: Shoulder and Elbow. American Academy of Orthopedic Surgeons, Rosemount, IL, 2008.
3. AAOS Clinical Practice Guideline Summary. Optimizing the Management of Rotator Cuff Problems, Robert A. Pedowitz et al. J Am Acad Orthop Surg June 2011;19:368-79.