Understanding AC Joint Problems: Causes, Symptoms, and Treatment

Comprehensive guide to AC joint injuries and arthritis, including causes, symptoms, diagnosis, and treatment options.

By Sneha Tete, Integrated MA, Certified Relationship Coach

Created on Oct 3, 2025

Comprehensive guide to AC joint injuries and arthritis, including causes, symptoms, diagnosis, and treatment options.

AC Joint Problems

The acromioclavicular (AC) joint is a critical connection where the collarbone (clavicle) meets the highest part of the shoulder blade (acromion). AC joint problems can range from acute injuries to chronic degeneration, often causing pain, shoulder weakness, and limited motion. Understanding the types, symptoms, causes, diagnostic strategies, and treatment options is essential for effective management and recovery.

What Is the AC Joint?

The AC joint is where the clavicle connects to the acromion of the shoulder blade. This small but important joint allows the arm to move overhead and across the body. While robust, the AC joint is susceptible to injury from trauma, overuse, or degenerative changes related to aging.

Causes of AC Joint Problems

AC joint issues can occur due to various factors, broadly categorized as traumatic injuries or degenerative conditions:

Trauma: Direct falls on the shoulder, car accidents, or sports injuries can damage the AC joint’s ligaments or bones.
Overuse: Repetitive overhead activities (e.g., weightlifting, painting) can lead to gradual wear and tear of the joint.
Degenerative Changes: Aging leads to cartilage breakdown (osteoarthritis), making the joint painful and stiff.
Sports Participation: Contact sports increase the risk of acute AC injuries.
Previous Injuries: Past trauma may predispose the joint to arthritis or recurrent instability.

Common Types of AC Joint Problems

AC Joint Separation: Tearing of ligaments holding the clavicle to the acromion, which may cause the bones to separate.
AC Joint Fracture: Fracture of the clavicle near the joint, often following significant trauma.
AC Joint Arthritis: Degeneration of the cartilage due to aging or repetitive use, causing chronic pain and stiffness.
Ligament Sprains: Stretching or partial tearing without full separation.

Symptoms of AC Joint Problems

The symptoms of AC joint problems vary based on the nature and severity of the issue. Common symptoms include:

Pain at the top of the shoulder, especially with movement or pressure.
Swelling around the point where the collarbone meets the shoulder blade.
Tenderness to touch, especially directly over the joint.
Limited Range of Motion, particularly when moving the arm overhead or across the body.
Weakness in the shoulder or arm, affecting normal function.
Visible bump or deformity above the shoulder (in cases of separation).
Crepitus (a crackling or popping sensation) with movement.
Difficulty sleeping on the affected side due to pain.
Bruising (especially after acute injury).

Diagnosis of AC Joint Problems

Diagnosing AC joint issues requires a comprehensive approach, including a clinical examination and imaging studies:

Physical Exam: The physician will assess pain, instability, and loss of motion by moving the arm in different directions and palpating the AC joint.
Medical History: Information regarding recent trauma, overuse, or previous shoulder injuries is crucial in forming a diagnosis.

Imaging Tests:

X-rays: Used to evaluate bone injuries (fractures, joint separation, or arthritis). X-rays help to distinguish between mild and severe separations.
MRI: Provides detailed images of soft tissues (ligaments, cartilage, and tendons), revealing inflammation, tears, or degeneration.
Ultrasound: Can be used to assess soft tissue injuries and guide injections.

These diagnostic strategies help differentiate between mild strains, severe separations, fractures, and degenerative changes.

Common AC Joint Injuries and Conditions

AC Joint Separation

This injury occurs when the ligaments connecting the clavicle and acromion are torn, often after a fall or direct blow. Separation severity is classified into grades:

Grade I: Mild sprain with minor pain, no visible deformity.
Grade II: Partial tear, moderate pain, slight bump above the joint.
Grade III: Complete ligament tear, significant pain and visible bump.
Grades IV-VI: More severe, involving additional ligament ruptures and clear misalignment.

AC Joint Fracture

A fracture near or through the AC joint, usually resulting from high-energy trauma or falls. More common in children and adolescents due to the late maturation of the clavicle. Classic symptoms include sudden pain, bruising, a prominent deformity, and inability to lift the arm.

AC Joint Arthritis

Degeneration of the joint cartilage—either due to advancing age, overuse, or after previous trauma. Common symptoms develop slowly and include pain at rest and when moving the arm, tenderness, mild swelling, and occasional popping sensations. Pain may worsen with overhead activities or sleeping on the affected side. Arthritis is a particularly frequent consequence in those with a history of AC joint injury.

Treatment Options for AC Joint Problems

Treatment depends on the type and severity of the injury or condition. The majority of AC joint conditions are initially managed with non-surgical treatments. However, severe injuries or arthritis unresponsive to conservative care may require surgical intervention.

Non-Surgical Treatments

Rest and Activity Modification: Avoiding activities that aggravate pain, especially overhead or across-the-body movements, helps decrease symptoms.
Ice Application: Applying ice packs to the shoulder reduces swelling and pain due to acute injury.
Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen are commonly recommended to control pain and inflammation. Use should be monitored if taken for more than 1 month due to potential side effects.
Steroid Injections: Corticosteroid injections into the AC joint can reduce inflammation and pain, providing temporary relief (usually for 2–3 months). Injections may be used under ultrasound guidance for precision.
Physical Therapy: Gradual strengthening and range-of-motion exercises restore function. A therapist may recommend a tailored routine to help regain mobility and strength.
Slings or Immobilization: Brief use of an arm sling after acute injury can limit motion and decrease discomfort, especially during the initial healing phase.

Surgical Treatments

Ligament Reconstruction: Repair or reconstruction of torn ligaments for severe separations or chronic instability.
Distal Clavicle Resection: Removal of the end of the clavicle in advanced arthritis to prevent bone-on-bone contact.
Fixation Devices: Plates, screws, or other hardware may be used to stabilize a fractured or dislocated clavicle.
Arthroscopic and Open Procedures: Minimally invasive techniques are available for some injuries; open surgery may be required for complex cases.

Surgery is usually considered only when non-surgical treatments have failed to relieve symptoms or when the injury is too severe to heal adequately without operative repair.

Recovery and Prognosis

With proper management, most AC joint injuries and arthritis can be successfully treated:

Mild Sprains and Injuries: Often heal within several weeks using conservative measures.
Moderate to Severe Injuries: May require months of rehabilitation or surgical intervention.
Arthritis: Symptoms may wax and wane, with periodic flares. Long-term management focuses on symptom control and maintaining function.
Physical Therapy: Consistent therapy improves mobility, reduces pain, and accelerates return to activity.

Most individuals can return to regular activities with time and appropriate care. Early treatment and adherence to rehabilitation regimens are important for optimal recovery.

Prevention of AC Joint Problems

While not all AC joint problems are preventable, taking certain measures can reduce risk:

Avoid repetitive overhead activities when possible, or ensure proper technique and ergonomics.
Use protective equipment during contact sports.
Address minor injuries promptly to prevent worsening.
Engage in strength and conditioning programs for shoulder stability.
Maintain joint health with a balanced exercise routine and flexibility training.

Table: Quick Comparison of AC Joint Conditions

Condition	Main Cause	Symptoms	Treatment
Separation	Trauma (fall/blow)	Pain, bump, instability	Rest, NSAIDs, PT, surgery (severe)
Fracture	High-impact injury	Sudden pain, deformity, bruising	Sling, pain meds, surgery (if displaced)
Arthritis	Wear-and-tear, aging	Pain, stiffness, swelling	NSAIDs, injections, PT, surgery (rare)

Frequently Asked Questions (FAQs)

Q: What are the first signs of AC joint problems?

A: The earliest signs are pain and tenderness at the top of the shoulder, worsened by moving the arm overhead or across the chest. Swelling and loss of motion may also be present.

Q: Can AC joint injuries heal on their own?

A: Many mild AC joint sprains and separations can heal with rest, ice, and physical therapy. Severe injuries, or those causing persistent symptoms, may require surgical repair.

Q: How is AC joint arthritis different from other shoulder arthritis?

A: AC joint arthritis affects the small joint where the clavicle meets the acromion, not the main ball-and-socket (glenohumeral) joint. It typically causes localized pain on top of the shoulder and is often triggered by wear-and-tear from repetitive activity or previous injury.

Q: When should I see a doctor for shoulder pain?

A: See a healthcare provider if your shoulder pain is severe, persistent, associated with swelling or visible deformity, or if you have difficulty moving your arm. Early diagnosis can help guide the most effective treatment plan.

Q: What sports or occupations are at greatest risk?

A: Athletes in contact sports (football, hockey, rugby), weightlifters, and individuals whose work involves frequent overhead activity (painters, construction workers) are most at risk for AC joint injuries and arthritis.

Key Takeaways

The AC joint is vital for shoulder movement and vulnerable to both injury and degeneration.
Early signs include pain, limited motion, and swelling on top of the shoulder.
Most cases can be managed conservatively, but severe injuries or deterioration may require surgical intervention.
Proper preventive strategies and prompt treatment offer the best outcomes for recovery and function.

References

Author

Sneha TeteBeauty & Lifestyle Writer

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to thebridalbox, crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

Read full bio of Sneha Tete