What are the causes and treatment options for pain in the shoulder rotator cuff?

Rotator Cuff Pain: Causes and Treatment

For rotator cuff-related shoulder pain, begin with structured exercise therapy combined with NSAIDs for 8-12 weeks, reserving surgery only for patients with full-thickness tears who fail conservative management. 1, 2, 3

Causes of Rotator Cuff Pain

The rotator cuff can be injured through several mechanisms:

• Tendinopathy/Tendinosis: Chronic degenerative process showing tendon enlargement with heterogeneous signal on imaging, often from repetitive overhead activities or eccentric overload 1, 2
• Partial-thickness tears: Most commonly occur at the articular (undersurface) of the tendon, followed by bursal surface or intrasubstance tears 1
• Full-thickness tears: Complete disruption of tendon from inferior to superior surface, which may be asymptomatic in 10% of cases 1
• Impingement syndrome: Results from acromioclavicular joint arthritis, calcified coracoacromial ligament, or abnormal acromion morphology 4
• Subacromial bursitis: Inflammation of the bursa contributing to pain with overhead motion 1

Initial Diagnostic Approach

Obtain plain radiographs first to assess for fracture, shoulder alignment, and bony abnormalities before considering advanced imaging 1, 2

Key clinical findings that suggest rotator cuff tears include:

• Pain with overhead activities 5
• Weakness on empty can test and external rotation testing 5
• Positive impingement sign 5
• Pain at night and with shoulder range of motion 1

Conservative Treatment (First-Line)

Start all patients with conservative management for 8-12 weeks before considering surgery, as this approach shows large effect sizes in reducing pain and improving function 2, 3

Recommended conservative interventions:

• NSAIDs or COX-2 inhibitors: Use as baseline analgesics for pain control 1, 2, 4
• Paracetamol (acetaminophen): Can be used for additional pain relief 1
• Structured exercise therapy: Gentle stretching, mobilization techniques, and progressive strengthening of shoulder girdle muscles 1, 2
• Physical therapy: Focus on restoring range of motion, particularly external rotation and abduction 1

Critical caveat on corticosteroid injections:

Avoid corticosteroid injections initially - the evidence is conflicting and they may compromise tendon biology and healing capacity 1, 2. One level II study found no significant difference between corticosteroid with lidocaine versus lidocaine alone at 6 weeks 1. However, subacromial corticosteroid injections may be considered when pain is specifically related to subacromial bursa inflammation after other measures fail 1.

Advanced Imaging Indications

Reserve MRI without contrast for patients who fail to respond to 8-12 weeks of conservative management 2

• MRI accurately identifies full-thickness tears with high sensitivity and specificity, showing increased signal intensity extending from inferior to superior tendon surface 1
• MR arthrography is preferred when distinguishing between full-thickness and partial-thickness tears, or for evaluating suspected retears after prior repair 1
• Ultrasound is equivalent to MRI for rotator cuff assessment when local expertise is available 1

Surgical Indications

Surgery should only be considered after failed conservative treatment of 3-6 months, or if imaging reveals significant full-thickness rotator cuff tear 2, 3

The evidence strongly supports this approach:

• A 2021 pragmatic RCT with 2-year follow-up found non-surgical and surgical treatments provided equivalent pain reduction and functional improvement overall 3
• However, for full-thickness ruptures specifically, surgery yielded superior improvement in pain (13-point difference, p=0.002) and function (7-point difference, p=0.008) 3
• For chronic symptomatic full-thickness tears, rotator cuff repair is an option, with 81% reporting excellent results versus 37% with non-surgical treatment 1

Important surgical considerations:

• Do not operate on asymptomatic full-thickness tears - asymptomatic rotator cuff disease is highly prevalent in older populations, and surgery is not indicated without significant pain 1
• Arthroscopic technique is preferred over open repair when feasible 1
• Tendon retraction, muscle atrophy, and fatty infiltration on imaging influence surgical planning and prognosis 1

Postoperative Pain Management (If Surgery Performed)

Use multimodal analgesia with interscalene brachial plexus block (continuous or single-shot) as the cornerstone 1

Recommended perioperative regimen:

• Pre/intraoperative: Paracetamol, COX-2 inhibitor, and IV dexamethasone 1
• Regional anesthesia: Interscalene brachial plexus block (Grade A evidence) or suprascapular nerve block with/without axillary nerve block as alternative 1
• Postoperative: Continue paracetamol and COX-2 inhibitor/NSAID, with opioids reserved for rescue only 1

Common Pitfalls to Avoid

• Do not assume prior imaging remains current - acute exacerbations may represent progression of pathology or new rotator cuff involvement 2
• Do not overlook scapular dyskinesis - this contributes significantly to both rotator cuff and labral injuries and must be addressed in rehabilitation 2
• Do not rush to surgery - most patients show significant improvement after 8 weeks of exercise therapy 2
• Do not ignore red flags - assess for cervical disk disease, acromioclavicular joint disease, and shoulder instability which can mimic rotator cuff pain 1, 5