What are the differentials and management options for new onset shoulder pain without trauma?

Differential Diagnoses for New Onset Shoulder Pain Without Injury

Primary Differential Diagnoses

For patients over 35-40 years presenting with atraumatic shoulder pain, rotator cuff disease and degenerative changes are the predominant causes, while cervical radiculopathy must be ruled out if pain radiates down the arm with neurological symptoms. 1, 2

Most Common Etiologies by Age and Location

Age >35-40 years:

• Rotator cuff tendinopathy or tear - anterior shoulder pain worsened by overhead activities, weakness with abduction and external rotation 2, 3
• Adhesive capsulitis (frozen shoulder) - progressive loss of both active and passive range of motion in all planes 4
• Glenohumeral osteoarthritis - pain with motion, crepitus, restricted range of motion 4
• Subacromial bursitis - pain with overhead activities, positive impingement signs 5

Age <35 years:

• Labral tears - mechanical symptoms, clicking, instability sensation 6
• Glenohumeral instability - sensation of shoulder "giving way" during activities 6

Location-Specific Diagnoses:

• Anterior shoulder pain - rotator cuff or biceps tendon pathology 1, 2
• Superior shoulder pain - acromioclavicular joint disease 2
• Scapular region pain - referred pain from cervical spine or rotator cuff 2

Critical "Cannot Miss" Diagnoses

• Cervical radiculopathy - pain radiating down arm with numbness, tingling, weakness in dermatomal distribution; most commonly from herniated discs or osteophytes 1
• Septic arthritis - fever, constitutional symptoms, acute onset; requires immediate specialist referral 3
• Occult fracture - especially in elderly with osteoporosis, can occur with minimal unrecognized trauma 3
• Malignancy - unexplained weight loss, night pain, progressive symptoms 7

Diagnostic Approach Algorithm

Step 1: Initial Clinical Assessment

Document these specific history elements:

• Exact pain location and radiation pattern to distinguish shoulder pathology from cervical radiculopathy 1, 2
• Aggravating factors: overhead activities suggest rotator cuff; cross-body adduction suggests AC joint 2
• Neurological symptoms: numbness, tingling, weakness radiating down arm strongly suggests cervical radiculopathy 1
• Sensation of instability or "giving way" suggests labral tear or glenohumeral instability 2
• Night pain and inability to sleep on affected side suggests rotator cuff pathology 7

Key physical examination findings to differentiate:

• Rotator cuff pathology: weakness with abduction/external rotation, positive empty can test, positive external rotation weakness 2
• Cervical radiculopathy: sensory changes in dermatomal distribution, weakness in specific myotomes, positive Spurling's test 1
• AC joint disease: tenderness over AC joint, positive cross-body adduction test 2
• Adhesive capsulitis: restricted passive and active range of motion in all planes 4

Step 2: Initial Imaging

Obtain standard shoulder radiographs (3 views minimum) as the mandatory first step for ALL patients with new shoulder pain, regardless of suspected etiology. 6, 3

Required views:

• AP views in internal and external rotation
• Axillary or scapula-Y view 6

Radiographs effectively demonstrate fractures, dislocations, arthritis, AC joint pathology, and calcific tendinitis 6, 3

Step 3: Advanced Imaging Based on Clinical Suspicion

If radiographs are normal or indeterminate:

For suspected cervical radiculopathy (pain radiating down arm with neurological symptoms):

• MRI cervical spine without contrast is the preferred initial advanced imaging - directly visualizes disc herniations, osteophytes, and nerve root compression 1
• Plain cervical spine radiographs may be obtained first to assess gross structural abnormalities 1
• Do NOT assume "muscle tension" without ruling out structural cervical spine pathology 1

For suspected rotator cuff pathology (anterior shoulder pain, overhead activity pain):

• MRI shoulder without contrast OR ultrasound shoulder are equivalent first-line options 6
• MRI is preferred if large body habitus, restricted range of motion due to pain, or suspicion of other intra-articular pathology like labral tears 6
• Ultrasound is excellent if local expertise available 3

For suspected labral tear (mechanical symptoms, instability):

• MRI shoulder without contrast is preferred in acute/subacute setting when joint effusion provides natural contrast 6
• MR arthrography is the reference standard in chronic setting when effusion has resolved 6

For suspected occult fracture:

• CT shoulder without IV contrast OR MRI shoulder without contrast - CT provides detailed osseous anatomy; MRI demonstrates bone marrow edema 6

Management Algorithm

Conservative Management (First-Line for Most Conditions)

Most soft-tissue shoulder injuries can undergo conservative management before considering surgery. 6

Pain Management Hierarchy:

1. First-line: Acetaminophen - maximum 4 grams daily; provides pain relief comparable to NSAIDs without GI toxicity, especially important in elderly 3, 8

2. Second-line: Topical agents - methyl salicylate, capsaicin cream, or menthol for mild-moderate pain 3

3. Third-line: NSAIDs - ibuprofen 400mg every 4-6 hours as needed (maximum 3200mg daily) 9

   • Critical caveat: Elderly patients are at exceptionally high risk for GI, platelet, and nephrotoxic effects; avoid long-term use 3
   • Use lowest effective dose for shortest duration 9

4. Intra-articular glucocorticoid injections - beneficial for pain not adequately relieved by systemic medications, especially with evidence of inflammation 3, 10

   • Subacromial injection for rotator cuff/bursitis
   • AC joint injection for AC arthritis
   • Glenohumeral injection for adhesive capsulitis or arthritis 10

5. Opioids - may be preferable to NSAIDs in elderly for severe refractory pain 3

Physical Therapy Protocol:

• Refer to rehabilitation specialist for comprehensive management - most rotator cuff pathology managed conservatively initially 1
• Range of motion exercises through stretching and mobilization, focusing on external rotation and abduction 3
• Avoid overhead pulleys - encourage uncontrolled abduction and may worsen pain 3
• Scapular stabilization exercises for rotator cuff pathology 2
• Electrical stimulation to improve shoulder lateral rotation 3

If cervical radiculopathy confirmed:

• Pregabalin 300-600mg daily in divided doses for neuropathic pain 1
• Alternative nerve-stabilizing agents: gabapentin or duloxetine 1
• Consider botulinum toxin type A injections for cervical dystonia or muscle spasms 1

Red Flags Requiring Urgent Specialist Referral

Immediate referral indicated for: 3

• Suspected septic arthritis (fever, constitutional symptoms)
• Neurological deficits
• Unstable or significantly displaced fractures on imaging
• Shoulder joint instability with recurrent dislocations
• Suspected massive rotator cuff tears in younger active patients

Elective orthopedic referral for:

• Failure of 6-12 weeks appropriate conservative treatment 7
• Progressive functional decline despite therapy 7

Critical Pitfalls to Avoid

• Do NOT assume absence of trauma means absence of fracture in elderly - osteoporotic fractures occur with minimal or unrecognized trauma 3
• Do NOT delay cervical spine imaging if pain radiates down arm with neurological symptoms - this is cervical radiculopathy until proven otherwise 1
• Do NOT prescribe NSAIDs without detailed medication history including over-the-counter use; drug interactions are common in elderly 3
• Do NOT order MRI before plain radiographs - radiographs must be obtained first in all cases 6, 3
• Do NOT assume "muscle spasm" without ruling out structural pathology when cervical radiculopathy suspected 1