Acromioclavicular Arthritis Causes, Symptoms & Treatment

Overview

The acromioclavicular (AC) joint, located at the junction of the clavicle and the acromion of the scapula, plays a key role in shoulder mobility, enabling arm elevation and cross-body movement. Arthritis of this joint, referred to as acromioclavicular arthritis, is characterized by inflammation, pain at the AC joint, and pain with shoulder movement. 

A related condition, commonly observed in weightlifters, is distal clavicular osteolysis, often termed “weightlifter’s shoulder,” which involves resorption of the distal end of the clavicle.

Degenerative AC changes typically present with localized pain and painful shoulder motion during upper extremity activities, particularly involving overhead or cross-body movements. Consequently, acromioclavicular joint arthritis can markedly impair functional capacity and athletic performance.

What causes Acromioclavicular Arthritis?

Acromioclavicular (AC) arthritis develops gradually due to repetitive stress and overuse of the AC joint. The joint surfaces are protected by cartilage that allows smooth movement between the clavicle and acromion. 

Over time, inflammation or degeneration of this cartilage can expose the underlying bone, causing friction and progressive wear. This repetitive stress may lead to microfractures at the distal end of the clavicle, a condition known as distal clavicular osteolysis or “weightlifter’s shoulder.”

• How the Injury Occurs: AC arthritis typically results from chronic joint overload, where repetitive compression or shearing forces exceed the cartilage’s ability to repair itself. This process gradually leads to cartilage thinning, joint inflammation, and eventual bone-on-bone contact.
• Common Everyday Causes: Individuals performing repetitive overhead tasks, such as painters, carpenters, and mechanics, may develop AC arthritis due to chronic shoulder loading. Similarly, professionals who frequently lift heavy objects or perform manual labor are at increased risk of developing degenerative changes in the AC joint over time.

Sports Commonly Associated with AC Arthritis

• Bodybuilding: Repetitive heavy pressing movements, such as bench and shoulder presses, place continuous strain on the AC joint.
• Football: Frequent tackles and shoulder impacts increase joint stress and risk of degenerative changes.
• Rugby: Constant collisions and arm movements during scrums can accelerate AC joint wear.

Symptoms

Acromioclavicular (AC) arthritis often presents with a gradual onset of discomfort and stiffness in the shoulder region. Individuals may experience one or more of the following symptoms, which can vary in intensity depending on the stage of the condition and activity level:

• Pain localized at the top of the shoulder, sometimes radiating toward the neck or upper back: This discomfort typically worsens with pressure over the joint or during movements involving the upper arm.
• Increased pain following physical activity or exercise: Lifting weights, push-ups, or overhead motions often aggravate symptoms due to repetitive stress on the AC joint.
• Reduced or restricted range of motion, particularly when reaching across the chest or lifting the arm overhead: This limitation may interfere with daily tasks, such as dressing, reaching for objects, or performing athletic movements.

In advanced cases, patients may also notice tenderness upon touch, mild swelling over the joint, or a clicking sensation during shoulder motion, all of which indicate progressive AC joint degeneration.

Non-operative treatment

Early-stage acromioclavicular (AC) joint degeneration and distal clavicular osteolysis, commonly called weightlifter’s shoulder, are typically managed through conservative, non-surgical interventions. The primary goal of treatment is to reduce inflammation, relieve pain, and restore functional movement of the shoulder.

If you have been diagnosed with AC joint arthritis or weightlifter’s shoulder, your orthopedic specialist may recommend the following non-operative measures:

• Activity modification: Avoid repetitive or strenuous activities aggravating shoulder top pain, such as hefty lifting or overhead movements.
• Cold therapy: Apply ice packs regularly to the affected area to minimize inflammation and swelling.
• Anti-inflammatory medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed to help control pain and reduce joint inflammation.
• Corticosteroid injections: Administered by your orthopedic specialist, these injections provide targeted relief from inflammation and pain within the joint.
• Physical therapy: A structured rehabilitation program focusing on improving the range of motion, strengthening supporting muscles, and restoring shoulder stability.

Adherence to these conservative treatments can significantly alleviate symptoms and, in many cases, prevent the need for surgical intervention.

Try these exercises to help address your condition:

Below is a PDF of the Exercise Program

AC Arthritis

Surgical Treatment

Surgical intervention may be recommended when conservative management fails to provide adequate relief. In cases of acromioclavicular (AC) arthritis or distal clavicular osteolysis, the procedure involves removing the damaged portion of the distal clavicle and, if necessary, the affected cartilage of the AC joint.

The primary objective of surgery for acromioclavicular (AC) arthritis or weightlifter’s shoulder is to eliminate pain while preserving shoulder mobility and strength. This operation, known as the Mumford procedure or AC joint arthroplasty, entails excising a small segment of the clavicle to prevent bone-on-bone contact. Depending on the patient’s condition and the surgeon’s preference, the procedure can be performed arthroscopically or through a minimally invasive open approach.