The Centers for Advanced Orthopaedics
Maryland Orthopedic Specialists
A Division of The Centers for Advanced Orthopaedics
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Shoulder

AC Joint Arthritis

Acromioclavicular (AC) joint arthritis is a common source of shoulder pain, causing pinpoint discomfort at the top of the shoulder with overhead activities and cross-body movements. Whether from prior injury or age-related wear, Maryland Orthopedic Specialists offers targeted treatments — from diagnostic injection to minimally invasive surgical resection — to provide lasting relief.

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What is ac joint arthritis?

The acromioclavicular joint is a small diarthrodial joint between the distal clavicle and the acromion of the scapula, separated by a fibrocartilaginous disc. Despite its small size, it is subjected to high loads during overhead and cross-body activities. It is one of the most common joints to become arthritic.

The acromioclavicular joint is a small diarthrodial joint between the distal clavicle and the acromion of the scapula, separated by a fibrocartilaginous disc. Despite its small size, it is subjected to high loads during overhead and cross-body activities.

AC joint arthritis develops through two main mechanisms:

  • Post-traumatic OA: Cartilage and disc damage sustained during an AC joint separation (any grade) accelerates degenerative change. Even minor Grade I–II injuries can lead to symptomatic arthritis years later.
  • Primary (idiopathic) OA: Age-related degeneration, particularly in overhead athletes (weightlifters, throwing athletes) and manual laborers. Distal clavicle osteolysis — stress-related resorption of the distal clavicle — is a specific variant seen in weightlifters.

AC joint arthritis is frequently discovered as a coexisting diagnosis in patients presenting for shoulder impingement, rotator cuff tears, or biceps pathology. Superior osteophytes from the AC joint can contribute to subacromial impingement and rotator cuff abrasion.

Treatment options

Corticosteroid Injection (Diagnostic and Therapeutic)

An AC joint corticosteroid injection is simultaneously the best diagnostic test and initial therapeutic intervention. Ultrasound guidance is preferred to ensure accurate intra-articular placement in this small joint. Most patients achieve meaningful pain relief for weeks to months, and many are managed long-term with periodic injections.

Activity Modification and Physical Therapy

Reducing heavy overhead and cross-body loading — particularly heavy bench press and wide-grip exercises — decreases symptoms. PT focuses on periscapular strengthening and shoulder mechanics rather than directly treating the joint.

Surgical Procedure

Distal Clavicle Excision

Arthroscopic removal of the distal 5–8 mm of the clavicle to eliminate bone-on-bone contact causing AC joint arthritis pain. Frequently performed alongside rotator cuff repair or other shoulder procedures at the same sitting.

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Frequently Asked Questions

Is AC joint arthritis the same as a shoulder separation?
No. A shoulder separation is an acute ligament injury. AC joint arthritis is the degenerative sequel that can develop years later — either as a result of a prior separation or as primary age-related wear.
Can I wait to have surgery?
Yes. Surgery is entirely elective. Many patients manage AC joint arthritis long-term with activity modification and periodic injections, delaying or avoiding surgery indefinitely.
Will removing the end of the collarbone affect my shoulder strength?
No. The small amount of bone removed (5–10 mm) does not affect the structural integrity of the shoulder. Strength is preserved because the critical CC ligaments and muscle attachments remain intact.
How long does recovery take after distal clavicle resection?
Most patients begin gentle range-of-motion exercises within one to two weeks after surgery. Strength training progresses over the following six to eight weeks, and full return to overhead activities and sport typically occurs by three to four months. Recovery after arthroscopic surgery is generally faster than open surgery. Your MOS surgeon will provide a detailed rehabilitation protocol tailored to your shoulder and activity goals.
How is AC joint arthritis different from glenohumeral (main shoulder joint) arthritis?
AC joint arthritis affects the small joint at the top of the shoulder where the collarbone meets the shoulder blade, while glenohumeral arthritis affects the larger ball-and-socket joint. AC joint arthritis typically causes pain with cross-body movements and overhead reaching, and the pain is localized to the top of the shoulder. Glenohumeral arthritis tends to produce deeper, more global shoulder pain with rotation. Both conditions can coexist, and your MOS surgeon will evaluate each joint separately to determine which is responsible for your symptoms.

Meet the specialists

Christopher S. Raffo, MD

Christopher S. Raffo, MD

Orthopedic Surgery · Sports Medicine

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John J. Christoforetti, MD

John J. Christoforetti, MD

Orthopedic Surgery · Sports Medicine · Hip Preservation Surgery

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James S. Gardiner, MD

James S. Gardiner, MD

Orthopedic Surgery · Sports Medicine

Meet Dr. Gardiner →

Related conditions

AC Joint Injury / SeparationGlenohumeral Osteoarthritis
Medically reviewed by Christopher S. Raffo, MD
Last reviewed May 1, 2026

References

  1. Shaffer BS. Painful conditions of the acromioclavicular joint. J Am Acad Orthop Surg. 1999;7(3):176–188. doi: 10.5435/00124635-199905000-00005.
  2. Strobel CM, Chang TJ. Acromioclavicular joint arthrosis and arthritis. Clin Sports Med. 2023;42(4):621–635. doi: 10.1016/j.csm.2023.05.010.
  3. Flatow EL, Duralde XA, Nicholson GP, Pollock RG, Bigliani LU. Arthroscopic resection of the distal clavicle with a superior approach. J Shoulder Elbow Surg. 1995;4(1 Pt 1):41–50. doi: 10.1016/S1058-2746(05)80054-0.
  4. Pensak M, Grumet RC, Slabaugh MA, Bach BR Jr. Open versus arthroscopic distal clavicle resection. Arthroscopy. 2010;26(5):697–704. doi: 10.1016/j.arthro.2009.09.016.
  5. American Academy of Orthopaedic Surgeons. Acromioclavicular Joint Conditions. OrthoInfo. https://orthoinfo.aaos.org/en/diseases--conditions/acromioclavicular-joint-problems/