What is the best course of treatment for a 2-week history of right shoulder pain, possibly due to hyperextension, with symptoms including pain on abduction, external rotation, and a painful arch, limited abduction, and radiating pain to the lower arm when extended beyond 90 degrees, with no pain at rest?

Treatment of Acute Shoulder Pain with Painful Arc and Limited Abduction

Based on your clinical presentation of painful arc, limited abduction, anterior shoulder pain point, and pain with external rotation following possible hyperextension, you most likely have rotator cuff tendinopathy or impingement syndrome that requires conservative management with NSAIDs, gentle range of motion exercises focusing on external rotation and abduction, and consideration of corticosteroid injection if symptoms persist beyond 3-6 months. 1, 2, 3

Initial Diagnostic Considerations

Your symptom pattern—painful arc with abduction, anterior shoulder tenderness, pain radiating down the arm beyond 90 degrees, and pain-free rest—strongly suggests rotator cuff pathology or subacromial impingement rather than adhesive capsulitis (which would cause pain at rest and restricted passive motion) or instability (which would present with apprehension). 4

Critical Imaging Requirements

Before proceeding with treatment, you need proper imaging to rule out structural damage:

• Obtain upright radiographs with three views minimum: AP in internal rotation, AP in external rotation, and axillary or scapula-Y view 5
• Never skip the axillary or scapula-Y view—AP views alone frequently miss dislocations and AC joint injuries 2, 5
• Radiographs must be performed upright, not supine, to avoid underestimating malalignment 2, 5

If radiographs are normal but symptoms persist beyond 4-6 weeks, MRI or ultrasound should be obtained to evaluate for rotator cuff tears or labral pathology. 4

First-Line Conservative Management (Weeks 1-12)

Pain Control

• Start with acetaminophen or ibuprofen if no contraindications exist 1, 2
• NSAIDs serve as first-line pharmacological therapy to reduce pain and inflammation 6

Range of Motion Restoration

• Initiate gentle stretching and mobilization techniques focusing specifically on external rotation and abduction 1, 2
• Active range of motion should be increased gradually in conjunction with restoring alignment and strengthening weak muscles in the shoulder girdle 1
• The goal is preventing frozen shoulder development, as limitations in external rotation and abduction are the factors most significantly related to ongoing shoulder pain 1

Physical Therapy Focus

Physical therapy should target three objectives:

• Decrease motion-related pain (your symptoms suggest motion pain rather than rest pain, making PT highly effective) 6
• Increase shoulder ROM by identifying and targeting restricted soft tissues 6
• Protect the glenohumeral joint through rotator cuff strengthening exercises 6

Critical Pitfall to Avoid

Never use overhead pulleys—they encourage uncontrolled abduction and have the highest incidence of developing shoulder pain complications 1

Second-Line Interventions (If No Improvement by 6-12 Weeks)

Corticosteroid Injection

• Subacromial corticosteroid injection should be used when pain is thought to be related to rotator cuff or bursal inflammation 1, 2
• Intra-articular triamcinolone injections have significant effects on pain reduction 1
• ROM typically improves with injections, though improvements may not reach statistical significance 1

Adjunctive Modalities

Consider adding:

• Ice, heat, and soft tissue massage 1
• Functional electrical stimulation (which improves pain-free lateral rotation even when pain intensity doesn't change) 1

When to Consider Surgical Referral

Surgery should only be considered if conservative strategies fail after a 3-6 month period 3

The proportion of patients with shoulder pain requiring surgery is small, and surgical interventions should only be pursued when:

• Clear structural diagnosis is established with imaging 3
• Conservative management has been exhausted 3
• Specific surgical indications are met based on the diagnosis 3

Expected Timeline and Prognosis

Most rotator cuff disorders and impingement syndromes respond to conservative management within 3-6 months. 3, 7 The rate of treatment failure is actually higher in surgical groups compared to conservative groups for shoulder stiffness and pain conditions. 7

Your presentation at 2 weeks is still very early—continue conservative management with the structured approach above before considering any invasive interventions.