Understanding Arthritis of the AC Joint
The acromioclavicular (AC) joint is a small joint at the top of the shoulder where the collarbone meets the shoulder blade. Like other joints, it can develop arthritis and become a focused source of shoulder pain, distinct from problems deeper in the shoulder joint or rotator cuff.
Causes
AC joint arthritis typically develops from:
Age-related wear and tear of the joint cartilage.
A prior AC joint injury or separation (a common injury from falls or contact sports).
Repetitive overhead activity or weightlifting, especially bench pressing.
General osteoarthritis affecting multiple joints.
Symptoms
Common symptoms include:
Pain localized to the top of the shoulder, directly over the AC joint.
Pain that worsens with reaching across the body (like reaching for a seatbelt).
Pain with overhead activity or lifting.
Tenderness directly over the joint, sometimes with a visible bump.
Seek prompt medical care if: Shoulder pain follows a fall or injury with sudden inability to lift the arm, or comes with fever, redness, and warmth over the joint. Left shoulder or arm pain with chest pressure, shortness of breath, or sweating needs emergency care.
Imaging Studies to Consider
Imaging helps confirm AC joint arthritis as the source of pain:
X-ray of the shoulder, including a dedicated AC joint (Zanca) view, is the primary test, showing joint narrowing and bone spurs.
MRI of the shoulder is used if rotator cuff involvement is also suspected.
Physical Therapy, Home Exercise & Other Conservative Techniques
Before considering injections or other procedures, several non-invasive approaches are well studied and usually tried first:
Physical Therapy
Manual therapy to improve shoulder blade (scapular) movement and joint mobility.
Progressive strengthening of the rotator cuff and muscles around the shoulder blade.
Education on adjusting activities that load the top of the shoulder.
Home Exercise Program
Pendulum and gentle range-of-motion exercises.
Scapular stabilization exercises, like rows and wall push-ups.
Gradual, guided return to overhead activity as symptoms allow.
Other Studied Techniques
Activity modification: avoiding bench press, push-ups, and overhead lifting during flares.
Ice after activity to reduce inflammation.
Kinesiology taping may offer short-term symptom relief for some patients.
Interventional Treatment Options
Treatment focuses on directly targeting the AC joint:
AC joint corticosteroid injection: Injected directly into the small joint to reduce inflammation and pain; can be guided by ultrasound or done using anatomic landmarks.
Platelet-rich plasma (PRP) injection: There isn't much dedicated research on PRP for AC joint arthritis specifically, and a corticosteroid injection remains the more established first choice for this joint. We consider PRP here as a later option once other measures have been tried, typically as a single injection.
Acupuncture: A technique that may provide modest additional pain relief alongside other treatments.
Surgical referral: For refractory cases, referral for distal clavicle resection (removing a small portion of the collarbone) can relieve pain from the arthritic joint.
Neuromodulation: Spinal Cord & Peripheral Nerve Stimulation
Neuromodulation is rarely needed for isolated AC joint arthritis, but may be considered for chronic, refractory shoulder pain overall:
Peripheral nerve stimulation (PNS) of the suprascapular nerve: Can be considered for chronic shoulder pain that doesn't respond to the treatments above.
How Strong Is the Evidence?
A summary of the evidence supporting key treatments for AC joint arthritis:
How to read this: Strong means consistent results from multiple high-quality studies. Moderate means generally favorable results with some limitations. Mixed or early means results so far are inconsistent or still emerging. Limited means few or lower-quality studies; these options can still be considered in select cases following a discussion with your healthcare provider.
AC joint corticosteroid injection: Moderate evidence.
Acupuncture: Limited evidence.
Platelet-rich plasma (PRP): Limited evidence; can be considered in select cases.
Evidence reviewed November 2026. These ratings summarize published research and major medical society guidelines available at that time. Research continues to evolve, and we will go over the most current evidence for your situation at your visit.
Pain Psychology Techniques
Pain psychology techniques help manage chronic shoulder pain:
Graded activity pacing helps you gradually resume overhead and cross-body activities.
Cognitive behavioral therapy (CBT) for pain.
Relaxation training and diaphragmatic breathing.
Non-Opioid Medication Options
Non-opioid medications can help manage AC joint pain:
Anti-inflammatory and analgesic options
NSAIDs like ibuprofen or naproxen reduce joint inflammation.
Topical NSAID gel is applied directly over the joint.
Acetaminophen for additional pain relief.
Related Procedures
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Talk With Us About Your Options
Call 650-507-4113 or send us a message to schedule a consultation at our Daly City, Los Altos, or Stockton office. We will review what may be causing your pain and walk through the risks, benefits, and alternatives of each option with you.
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This information is provided for general patient education and does not replace individualized medical advice. Please discuss your specific symptoms, diagnosis, and treatment options with your pain management physician.
