What is the best treatment approach for a patient in their seventies with shoulder pain, limited mobility, and radiographic evidence of degenerative arthropathy of the acromioclavicular (AC) joint, but no acute fracture or malalignment?

Treatment of Degenerative AC Joint Arthropathy in a Septuagenarian with Shoulder Pain

For this patient with radiographically confirmed AC joint arthropathy and no acute fracture, initiate conservative management with NSAIDs (if no contraindications), activity modification, and consider ultrasound-guided corticosteroid injection if symptoms persist beyond 2-4 weeks, while obtaining advanced imaging (MRI or ultrasound) to evaluate for concurrent rotator cuff pathology given the inability to lift the arm. 1, 2

Initial Conservative Management

Start with a trial of oral analgesics and activity modification as first-line therapy:

• Prescribe NSAIDs (such as ibuprofen) or acetaminophen if no contraindications exist, as these are the foundation of initial AC joint osteoarthritis management 1, 2
• Instruct the patient to avoid aggravating activities, particularly overhead movements and cross-body adduction, which stress the AC joint 3, 2
• Physical therapy has limited benefit for isolated AC joint arthropathy, as therapeutic exercise and range of motion play only a minor role in this specific condition 2

Critical Diagnostic Consideration

The inability to lift the arm suggests concurrent rotator cuff pathology that requires immediate evaluation:

• AC joint arthropathy alone typically does not cause complete inability to lift the arm—this presentation strongly suggests coexisting rotator cuff disease 3, 2
• Order MRI without contrast or ultrasound (both rated 9/9 appropriateness) to evaluate for rotator cuff tear, as these modalities are equivalent for suspected rotator cuff pathology 4, 1
• The radiographic finding of bone demineralization in a septuagenarian increases risk for rotator cuff tears and should lower your threshold for advanced imaging 4

Corticosteroid Injection Protocol

If conservative measures fail after 2-4 weeks, proceed with ultrasound-guided AC joint injection:

• Perform ultrasound-guided injection of corticosteroid (such as 1 mL of betamethasone) into the AC joint, which provides short-term pain relief for AC joint osteoarthritis 5, 2
• Ultrasound guidance is preferred over blind injection to ensure accurate intra-articular placement and exclude other pathology 6, 2
• A diagnostic lidocaine injection can be performed first to confirm the AC joint as the pain source and may correlate with surgical outcome 2, 7
• Be aware that corticosteroid injections do not alter disease progression and provide primarily short-term benefit 2

Addressing the Functional Limitation

The inability to lift the arm requires specific rotator cuff-directed therapy:

• Once rotator cuff pathology is identified on MRI/ultrasound, implement gentle stretching and mobilization focusing on external rotation and abduction 1
• Progress to rotator cuff and scapular stabilizer strengthening once pain-free motion is achieved 3
• Test specific rotator cuff muscles individually: supraspinatus (empty can test), infraspinatus/teres minor (external rotation resistance), and subscapularis (lift-off test) to identify which tendons are affected 1

Surgical Referral Criteria

Consider orthopedic referral for distal clavicle resection if:

• Conservative management fails after a minimum of 6 months 2, 7
• The patient has persistent pain significantly limiting function despite appropriate conservative therapy 2, 7
• Open or arthroscopic distal clavicle resection is the definitive treatment, with emphasis on capsular preservation and minimal bone resection 7

Common Pitfalls to Avoid

Do not attribute all symptoms to the AC joint arthropathy visible on x-ray:

• Asymptomatic AC joint degeneration is extremely common and does not always correlate with symptoms—the inability to lift the arm is NOT typical of isolated AC joint disease 7
• In patients over 35-40 years, rotator cuff disease is the predominant cause of shoulder pain and functional limitation 3
• The x-ray recommendation for follow-up imaging in 10-14 days is appropriate only if occult fracture is suspected, but does not address the soft tissue pathology causing inability to lift the arm 4

Do not delay advanced imaging in a septuagenarian who cannot lift their arm:

• This degree of functional impairment warrants immediate MRI or ultrasound evaluation rather than waiting for failed conservative therapy 4, 1
• Tendon retraction, muscle atrophy, and fatty infiltration visible on MRI are critical findings that influence surgical candidacy and prognosis 4