AC Joint Arthritis
Degeneration of the Acromioclavicular Joint in the Shoulder
What Is AC Joint Arthritis?
AC (Acromioclavicular) joint arthritis is a form of osteoarthritis that affects the small joint where the clavicle (collarbone) meets the acromion of the scapula (shoulder blade). This joint is responsible for allowing arm elevation and shoulder rotation. Over time, wear and tear can lead to the breakdown of cartilage, resulting in joint inflammation, pain, and limited shoulder motion.
Causes and Risk Factors
Natural aging process and degenerative changes
Repetitive shoulder use or overhead lifting
Prior trauma or AC joint separation
Weightlifting and contact sports (e.g., football, rugby)
Occupations requiring frequent lifting or pushing
Previous surgery involving the shoulder or clavicle
Symptoms
Localized pain on the top of the shoulder
Pain when reaching across the body (e.g., putting on a seatbelt)
Tenderness over the AC joint
Swelling or a visible bump at the AC joint
Discomfort during push-ups, bench press, or overhead lifting
Limited range of motion, especially at the end range of elevation
Diagnosis
Physical exam: focal tenderness at the AC joint, pain with cross-body adduction test
X-rays typically show:
Joint space narrowing
Bone spurs (osteophytes)
Cyst formation or sclerosis
MRI may reveal cartilage loss and inflammation
Diagnostic lidocaine injection into the AC joint can confirm the source of pain
Treatment
Non-Surgical Treatment
NSAIDs to reduce inflammation and pain
Activity modification (avoiding aggravating movements)
Ice and topical analgesics
Physical therapy to:
Improve shoulder mechanics
Reduce strain on the AC joint
Corticosteroid injection into the AC joint for longer-lasting relief
Surgical Treatment
Indicated for persistent or severe symptoms despite conservative treatment
Common procedures:
Distal clavicle excision (also known as the Mumford procedure): removal of a small portion of the clavicle to eliminate bone-on-bone contact
Performed arthroscopically or via a mini-open approach
Usually a same-day outpatient procedure
Recovery Outlook
Many patients achieve long-term relief through non-surgical care
After distal clavicle excision:
Sling use for a few days to a week
Return to desk work in 1–2 weeks
Full recovery within 6–8 weeks
Return to weightlifting or high-demand activity typically in 3 months
Why Kerlan Jobe Institute?
Our orthopedic specialists at Kerlan Jobe Institute have deep expertise in managing AC joint arthritis using both conservative and minimally invasive surgical techniques. We focus on helping each patient return to pain-free motion and daily function.