What are the treatment options for AC (acromioclavicular) joint osteoarthritis?

Understanding AC Joint Osteoarthritis

AC (acromioclavicular) joint osteoarthritis is a common cause of shoulder pain where the cartilage between your collarbone and shoulder blade wears down, causing pain, stiffness, and difficulty with overhead activities and cross-body movements.

What Is Happening in Your Joint

The AC joint is where your collarbone (clavicle) meets the top of your shoulder blade (acromion). When osteoarthritis develops here, the protective cartilage breaks down, causing bone-on-bone contact that creates pain and inflammation 1. This is one of the most common disorders affecting the AC joint and can occur from normal wear-and-tear over time (primary osteoarthritis) or following an injury to the shoulder 2.

What You'll Experience

Pain Patterns

• Location: Pain typically occurs at the top of your shoulder where you can feel the bump of your collarbone meeting your shoulder blade 1, 2
• Activities that hurt: Reaching across your body (like fastening a seatbelt), lifting overhead, sleeping on the affected shoulder, and carrying heavy objects 1
• Radiation: Pain may spread into your neck, shoulder, or down your arm, which can be confusing 2

Physical Limitations

• Difficulty with daily activities like dressing, reaching into back pockets, or lifting objects 1
• Stiffness and reduced range of motion in the shoulder 2
• Tenderness when pressing directly on the AC joint 1

Treatment Options: A Step-by-Step Approach

First-Line Conservative Treatment (Try These First for 6 Months)

Start with pain medications and activity modification 3, 4, 1:

• Acetaminophen (Paracetamol): Regular dosing up to 4,000 mg daily for pain relief 5, 6
• Topical NSAIDs: Apply directly to the painful area with fewer side effects than pills 5, 6
• Oral NSAIDs: If topical treatments are insufficient, use oral anti-inflammatory medications (ibuprofen, naproxen) at the lowest effective dose for the shortest time 5, 4, 1
  • Always take with a proton pump inhibitor (like omeprazole) to protect your stomach 5
  • Your doctor should assess your heart, stomach, and kidney risk factors before prescribing 5, 6

Activity modification 1:

• Avoid overhead lifting and cross-body movements that aggravate pain
• Modify work and daily activities to reduce stress on the joint
• Use proper body mechanics when lifting

Physical Therapy (Limited Role)

Unlike other joints, physical therapy has a minor role in AC joint arthritis 1. Range of motion exercises and strengthening have limited benefit because the problem is primarily structural wear-and-tear in a small joint 1. However, maintaining shoulder mobility and addressing compensatory movement patterns may provide some relief 1.

Corticosteroid Injections (If Initial Treatment Fails)

Injections can provide short-term pain relief but don't change the disease progression 4, 1:

• A diagnostic injection with local anesthetic confirms the AC joint is the pain source 4, 1
• If the diagnostic injection provides relief, corticosteroid injections may offer temporary benefit 1
• Studies show approximately 50% improvement in pain levels at an average of 7.5 months follow-up 3
• The judicious use of steroid injections remains controversial, as they don't alter the natural course of the disease 1

Surgical Treatment (After 6 Months of Failed Conservative Care)

Distal clavicle excision (removing the end of the collarbone) is the definitive surgical treatment 3, 4, 1:

When to Consider Surgery

• Persistent pain after at least 6 months of appropriate conservative treatment 3, 1
• Significant functional limitations affecting daily activities and quality of life 3
• Confirmed diagnosis with positive response to diagnostic injection 4, 1

Surgical Options

Both approaches have similar excellent outcomes 3:

• Arthroscopic distal clavicle resection: Minimally invasive approach through small incisions 3, 4
• Open distal clavicle resection: Traditional open surgery 3, 4
• Studies show no significant difference between open and arthroscopic techniques in terms of outcomes 3

What to Expect from Surgery

• Amount of bone removed: 0.5 to 2 cm of the end of the collarbone produces good outcomes 3
• Average functional outcome: 87.8% improvement on standardized shoulder scores 3
• Recovery: Most patients return to work at an average of 214 days (approximately 7 months) 7
• Concomitant procedures: If you need other shoulder repairs (like rotator cuff), they can be done simultaneously with similarly good outcomes 3, 7

Important Considerations

Conservative Treatment First

Recent evidence shows that conservative management with rotator cuff repair (if needed) is as effective as adding distal clavicle resection in the short term, but with fewer risks and lower costs 7. This supports trying non-surgical approaches thoroughly before proceeding to surgery.

Avoid These Treatments

• Glucosamine and chondroitin: Not recommended as they haven't shown significant benefits 6, 8
• Electrotherapy/TENS: Low-quality evidence for benefit 9

Monitoring Your Progress

• Reassess your symptoms regularly with your doctor 9
• Document whether treatments provide meaningful pain relief and functional improvement 9
• If symptoms persist despite appropriate conservative treatment, discuss surgical referral 4, 1

The Bottom Line

Begin with oral or topical NSAIDs and activity modification for at least 6 months 3, 4, 1. If a diagnostic injection provides relief, consider therapeutic corticosteroid injections for temporary benefit 3, 1. Surgery should only be considered after exhausting conservative options, as it carries more risks and costs without proven superiority in the short term 7. When surgery is needed, both open and arthroscopic approaches produce excellent results in approximately 88% of patients 3.