Shoulder pain

Anatomy

• Rotator cuff provide 30-50% of abduction power and 90% of external rotation
• Supraspinatus
  • Supraspinous fossa of scapula to greater tuberosity of humerus
  • Initiates arm elevation and abducts the shoulder
• Infraspinatus
  • Infraspinous fossa of scapula to posterior aspect of greater tuberosity
  • Primarily external rotation
• Teres minor
  • Lateral border of scsapula to posterior aspect of humerus
  • External rotation
• Subscapularis
  • Subscapular fossa of scapula to lesser tuberosity
  • Internal rotation
• Extra-articular subacromial bursa is the only clinically relevant one

Coracoacromial arch

• Coracoid to acromion with coracoacromial ligament forming roof
• Humeral head is the floor
• Defines space through which rotator cuff tendons, tendon of long head of biceps and subacromial bursa lie

Impingement syndrome

• All encompassing term for subacromial bursitis, rotator cuff tendinitis, supraspinatus tendinitis and painful arc syndrome
• Caused by repetitive over heard activity with humeral head encroaching on subacromial space
• Stage I – Reversible oedema and haemorrhage of rotator cuff
  • Classicaly athletes <25yo
  • Dull ache over anterolateral shoulder aggravated by activity and relieved by rest
• Stage 2 – Tendinitis of rotator cuff with fibrosis and thickening of cuff and bursa
  • Typically aged 25-40 with prolonged duration and recurrence
  • Recurrent or chronic aching pain with daily activities, pain with vigorous activity and night pain
• Stage 3 – Rotator cuff tears, rupture of long head of biceps and subacromial spurs
  • Progressive symptoms, disability and often require surgical decompression of subacromial space

Impingement syndrome

• Typically pain, over weeks to months, over anterolateral shoulder, radiating to mid-humerus (but not below elbow)
• Often ache at night interfering with sleep
• Palpation of rotator cuff insertion at lateral aspect of proximal humerus produces pain
• When ranging, fibrosis and scarring lead to crepitus
• Painful arc 60-100 degrees suggests rotator cuff pathology
• Mild to moderate rotator cuff weakness due to pain
• Should test each rotator cuff muscle in turn
  • Supraspinatus – Empty can
  • Infraspinatus and teres minor – External rotation with arm adducted and elbow flexed 90 degrees
  • Subscapularis – Internal rotation with lift-off test behind back

Impingement syndrome

• Maneuver of Neer
  • Prevent scapular rotation with one hand and then raise patients straightened arm up in full forward flexion
  • Positive if pain in arc from 70-120 degrees
• Hawkins impingement test
  • Shoulder in 90 degrees abduction and 90 degrees elbow flexion
  • Rotate arm inward across front of patient with internal rotation
• Both 80-90% sensitive but not very specific

Impingement syndrome

• Diagnosis
  • History of chronic shoulder pain, full range of motion, weakness of rotator cuff and positive impingement testing
  • X-ray can exclude fracture or degenerative joint changes
  • Early non-specific X-ray findings include sclerosis and subchondral cysts of greater tuberosity of humerus or sclerosis or spur formation at anterior edge of acromion

Impingement syndrome

• Treatment
  • Relative rest, avoidance of overhead activity + range of motion exercises 3-4 times daily to prevent frozen shoulder
  • NSAID’s for 7-21 days + paracetamol +- opioids in short-term
  • Ice to affected shoulder 10-15 minutes QID
  • Pendulum swings
  • Stretching and strengthening with physiotherapy
  • Corticosteroid injections: LMO or ortho. Relieves pain but risks muscle atrophy, weakness and further tissue degeneration
  • F/u with ortho in 7-14 days or LMO

Rotator cuff tears

• Present with shoulder pain after acute traumatic injury, chronic injury or acute extension of stage 3 impingement syndrome
• Mostly acute on chronic over 40yo
• Consider rotator cuff tear in patients with weakness >3 weeks after an acute glenohumeral dislocation
• May be full or partial thickness
• Acute on chronic tears may be insidious with minimal clinical findings
• Acute tears are often severely painful, tearing sensation, inability to abduct or externally rotate arm against even mild resistance
• Drop-arm test positive if cannot hold at 90 degrees abductionn

Rotator cuff tears

• Diagnosis
  • Very difficult to distinguish partial vs. complete tear or rotator cuff injury from impingement syndrome
  • Mostly historical based on weakness with chronic shoulder pain or acute trauma
  • If unsure, treat as for complete tear and get follow-up
  • Routine X-ray may show narrowing of acromiohumeral space <7mm
  • MRI and US can assist in diagnosis but all tend to underestimate extent of tear

Rotator cuff tears

• Treatment
  • Treat as for impingement, arm sling until acute symptoms subside, however, avoid prolonged immobilisation due to risk of frozen shoulder
  • Refer all to ortho within a week
  • Complete tears usually require surgical repair and functional outcomes are better if repaired early before retraction, fibrosis, tendon degeneration and muscular atrophy
  • Partial tears and chronic tears respond well to conservative measures

Calcific tendonitis

• Self-limiting calcium crystal deposition within rotator cuff
• Calcium ultimately undergoes painful resorption with healing
• Mostly middle aged. Rare >70yo
• Primary tendon regeneration due to chronic repetitive microtrauma, age and tissue hypoxia are the causes
• Supraspinatus by far most common
  • Usually calcific deposits near insertion on humerus

Calcific tendonitis

• Clinical features
  • Generally asymptomatic or mild rest pain at night with subsequent incapacitating pain during resorption phase due to vascular proliferation, granulation tissue and calcium crystal extravasation into subacromial bursa
  • Often tender at supraspinatus insertion on humerus with limited shoulder ROM due to pain
  • Symptoms usually 1-2 weeks and self-limiting
• Following resorption phase, get variable shoulder pain for months in postcalcific phase
• Adhesive capsulitis is the most common complication

Calcific tendonitis

• Diagnosis
  • X-ray can localised deposits and show impingement
  • In resorptive phase, calcium deposits may appear hazy
  • Presence of calcifications is not diagnostic as need history
  • US unhelpful during resorptive phase as little or no acoustic shadowing
• Phases
  • Precalcific: Pain-free
  • Calcific:
    • Formative – Some pain
    • Resting – Lacks inflammation +- Pain
    • Resorptive – Most painful
  • Post-calcific

Calcific tendinitis

• Treatment
  • Treat as for impingement syndrome (conservative successful in 90%)
  • NSAID’s, opioids, ice
  • Sling for brief immobilisation
  • Rest shoulder in abduction as often as possible on back of chair
  • Sleep with pillow beneath axilla to prevent restricted ROM
  • Gentle and progressive ROM exercises
  • Physio if more chronic cases with significant limitation of ROM
  • No strong evidence for anything else
• Disposition
  • LMO within 1 week
  • If conservative management fails (10%) refer to ortho for consideration of arthroscopic surgery

Adhesive capsulitis

• Frozen shoulder
• Painful inflammation of glenohumeral joint, then fibrosis of joint capsule and restriction of shoulder motion
• Primary (idiopathic) related to diabetes, thyroid disease, postmenopausal, pulmonary neoplasm and autoimmune disorders
• Secondary results from prolonged immobilisation, surgery stroke or primary inflammatory condition of shoulder e.g. impingement syndrome or calcific tendinitis
• Resolves with conservative therapy for most patients in 1-2 years

Adhesive capsulitis

• Four stages
  • Stage 1 – 2-3 months of acute synovial inflammation with pain
  • Stage 2 – Freezing stage. Months 3-9 with decreased shoulder ROM from capsular thickening, scarring and chronic pain
  • Stage 3 – Frozen stage. Months 9-15 with less pain and more limitation of ROM
  • Stage 4 – Thawing stage. After 15 months get minimal pain and progressive improvement in ROM

Adhesive capsulitis

• Clinical diagnosis
• MRI has 70% sensitivity and 95% specificity for this if unclear
• Treatment
  • Avoid shoulder immobilisation
  • Can use sling in stage 1 for a few days
  • Physical therapy and NSAID’s, analgesics and ice are key in early phase to reduce pain and ensure ongoing ROM
  • Intra-articular steroid injection can improve pain and function in short-term
  • Refer to ortho if ongoing symptoms despite good physio for 6 months or if diagnosis unsure

Biceps tendon disorders

• Long head arises from superior labrum and supraglenoid tubercle of scapula (50% from labrum)
• Forces on biceps pulls labrum off glenoid producing SLAP (superior labrum anterior to posterior) lesions
• Clinical features
  • Tendinopathy causes rest pain, night pain and anterior shoulder tenderness

Biceps tendon disorders

• Diagnosis
  • Palpation of tendon in biciptal groove reproduces pain
  • Forearm supination (main action of long head of biceps) reproduces pain, especially against resistance
  • Subluxation of bicipital tendon may be palpated during supination against resistance
  • Speed’s test – flex shoulder to 90 with elbow extended and supinated. Provide downward resistance to shoulder flexion. Positive if pain at bicipital groove. 87% sensitive and 80% specific for long head of biceps tear

Biceps tendon disorders

• Diagnosis
  • Active compression test:
    • Flex shoulder to 90, adduct 10 to 15 degrees medially and rotate fully with elbow extended
    • Uniform downward pressure by examiner 
    • Repeat in full lateral position
    • Positive response is indicated by pain with first maneuver and reduction or elimination of pain with second maneuver
    • 60-100% sensitive and 85-98% specific for SLAP lesion
  • US very specific but poorly sensitive (very operator dependent)
  • MR arthrography is good but normal MRI not sensitive
  • Arthroscopy is considered gold standard but it also has poor inter-rater reliability

Biceps tendon disorders

• Treatment
  • Sling for comfort briefly, RICE
  • Early mobilisation and f/u within 2 weeks to LMO
  • Intra-articular steroids and LA can improve symptoms
  • Usually resolves with conservative therapy
  • Ortho consult for tendinopathy with instability, partial rupture, high-grade SLAP lesion or failure to respond to conservative therapy
  • Complete rupture requires ortho consult within 24-48 hours at best

Osteoarthritis

• Rare to have primary OA of shoulder as not weight-bearing
• Secondary is more common

Alternative causes of shoulder pain

• Neck is most common source of referred pain
  • C5-6 herniated disc pain can mimic rotator cuff
  • Careful C-spine and neurological examination is key
• Brachial plexus injury
• Brachial plexus neuritis
• Acute thrombosis of axillary artery (may be seen following repetitive overuse or explosive stress from lifting heavy objects with intimal damage)
• Compression of suprascapular nerve
• Thoracic outlet syndrome
• Pancoast’s tumor
• Myocardial ischaemia/infarction
• Abdominal disorders with diaphragm irritation including biliary tract, ectopic pregnancy, splenic injury/inflammation or perforated viscous

Last Updated on October 6, 2020 by Andrew Crofton