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AC Joint Osteoarthritis

AC joint osteoarthritis can reduce the mobility of the shoulder girdle, which consists of the two clavicles and the two shoulder blades as well as the connecting joints and muscles. 

The two pairs of joints that are part of the shoulder girdle are the sternoclavicular joint and the acromioclavicular joint  on each side.

The AC joints are particularly mobile and important. Unfortunately these are also the ones that tend to develop shoulder arthritis in the late 30’s or mid 40’s. At that time they are prone to develop a shoulder bone spur as part of osteoarthritis. This can cause sharp pain feeling like there are internal small knives in the shoulder. This is osteoarthritis pain. If they point down in the direction of the supraspinatus tendon, this can become the source of a rotator cuff injury and eventually a rotator cuff tear. In the presence of a congenital shoulder impingement this is particularly painful and devastating.

These cases need the attention of an orthopedic surgeon who can do a shoulder arthroscopy and clean out the spurs. Early detection by clinical examination and MRI scan are essential to prevent disaster (a supraspinatus tendon tear).

 AC Joint Osteoarthritis

AC Joint Osteoarthritis

In severe cases of AC joint arthritis shoulder surgery is required, where the AC joint is surgically removed by doing a shoulder decompression. This consists of cutting away the distal 1/3 of the clavicle (collar bone) and removal of a wedge of the acromion. This procedure often has to be done as an “open procedure” (meaning through a large incision) although most of the time shoulder surgeons first attempts to do this procedure by arthroscopy (through “pinhole surgery”).


1. ABC of rheumatology, second edition, edited by Michael L. Snaith , M.D., BMJ Books, 1999.

2. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999.

3. Goldman: Cecil Textbook of Medicine, 21st ed.(©2000)W.B.Saunders

4. Ferri: Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.

5. Rakel: Conn’s Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier

6. Wheeless’ Textbook of Orthopaedics: Several topics can be found under this link by entering the term you search for.

7. Suzanne Somers: “Breakthrough” Eight Steps to Wellness– Life-altering Secrets from Today’s Cutting-edge Doctors”, Crown Publishers, 2008

Last modified: July 10, 2019

This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.