Shoulder Strain

A strain is a partial or complete tear of muscle fibres or the musculotendinous junction around the shoulder, from sudden overload, forced stretching, or eccentric contraction. The muscles affected are the deltoid, rotator cuff muscles (supraspinatus, infraspinatus), trapezius, levator scapulae, rhomboids, latissimus dorsi, teres major, pectoralis major and the biceps.

• Grades: grade 1 (stretch with fewer than 5% of fibres torn, minimal strength loss), grade 2 (partial tear with 5 to 95% of fibres torn, moderate strength loss), grade 3 (complete rupture with a palpable gap).
• Causes: lifting heavy loads, a sudden jerk, falls, throwing, swimming, weight training (bench press injures pectoralis major), and poor warm up. Risk factors: age above 40, muscle imbalance, fatigue, previous injury, anabolic steroid use (pectoralis major rupture), and fluoroquinolone or corticosteroid exposure.
• Most strains recover with conservative treatment: grade 1 in 1 to 3 weeks, grade 2 in 4 to 8 weeks. Grade 3 injuries to the pectoralis major, deltoid or cuff may need surgery.

• Sudden pain at the time of injury, sometimes with a tearing sensation or pop, followed by localised pain, swelling, bruising (tracking down the arm or chest wall in pectoralis major tears) and tenderness over the muscle belly. Pain with active contraction of the muscle and with passive stretching.
• Grade 2: weakness on resisted testing with pain, and reduced range. Grade 3: marked weakness, a visible defect or retracted muscle bulge, and loss of axillary fold contour (pectoralis major).
• Differential diagnosis: rotator cuff tear, acromioclavicular sprain, glenohumeral dislocation or subluxation, clavicle and humerus fracture, labral injury, brachial plexus injury, cervical radiculopathy, suprascapular nerve injury, and referred visceral pain.
• Red flags: obvious deformity, a palpable gap, severe weakness, neurovascular compromise, expanding haematoma, and chest pain with arm pain.
• Complications: chronic pain, scar tissue and recurrent strain, weakness, myositis ossificans, and in tears of the pectoralis major, persistent weakness and cosmetic deformity.

• Clinical, based on the mechanism, the muscle's resisted tests, palpation and comparison with the other side. Check neurovascular function and the cervical spine.
• X-ray if bony injury or avulsion is possible. Ultrasound confirms the grade and haematoma and guides aspiration. MRI for suspected complete rupture, cuff tear, and surgical planning.

• First 48 to 72 hours: relative rest and protection of the shoulder (a sling for comfort only, for 1 to 3 days), ice for 10 to 15 minutes every 2 to 3 hours, gentle compression, and avoidance of heat, alcohol and vigorous massage.
• Analgesia: paracetamol 1 g orally 6 hourly. Ibuprofen 400 mg orally 8 hourly with food (or naproxen 500 mg 12 hourly) for 3 to 5 days if needed. Topical diclofenac 1% gel 2 to 4 g 3 to 4 times daily.
• Rehabilitation:
  • Days 3 to 7: pendulum and pain free active assisted range of movement.
  • Weeks 1 to 3 (grade 1) or 2 to 6 (grade 2): isometric then progressive resistance exercises, scapular stabilisation, and stretching.
  • Return to overhead and contact sport when there is full pain free range and strength of at least 90% of the other side, usually 2 to 4 weeks for grade 1 and 6 to 10 weeks for grade 2.
• Large haematoma: ultrasound guided aspiration for painful tense collections.
• Grade 3 and specific tears:
  • Pectoralis major rupture in active patients: surgical repair within 3 to 6 weeks gives the best results, with a sling for 4 to 6 weeks and strengthening from 3 months.
  • Acute full thickness cuff tear in an active patient: early repair.
  • Complete deltoid avulsion: repair.
• Do not inject corticosteroid into acute muscle strain. Avoid NSAIDs beyond 1 to 2 weeks because they may impair healing.
• Special groups:
  • Elderly: lower load rehabilitation, with a higher chance of an underlying cuff tear.
  • Anabolic steroid users and fluoroquinolone users: stop the drug and assess for tendon rupture.
  • Pregnancy: ice, paracetamol and positioning. Avoid NSAIDs after 20 weeks.
  • Anticoagulation: expect larger haematoma, review at 48 hours.
  • Renal impairment and gastrointestinal disease: avoid oral NSAIDs.
• Follow up: review at 1 to 2 weeks and at 6 weeks. Refer to orthopaedics for a palpable gap, severe weakness, no improvement by 6 weeks, or high demand athletes with a grade 3 injury.