Dr Puah Ken Lee 潘健理
Orthopaedic Surgeon
Shoulder, Elbow & Sports Injuries
Practising at Mount Elizabeth Novena Hospital, Singapore
Appointments by prior arrangement
Dr Puah Ken Lee 潘健理
Orthopaedic Surgeon
Shoulder, Elbow & Sports Injuries
Mount Elizabeth Novena Hospital, Singapore
✔ Subspecialty Focus in Shoulder & Elbow, Sports Injuries
✔ Practising at Mount Elizabeth Novena Hospital
✔ Evidence-based treatment, Individualised Care
AC Joint Arthritis
Acromioclavicular (AC) joint arthritis is a common cause of pain at the top of the shoulder. It develops when the cartilage within the small joint between the collarbone (clavicle) and the acromion gradually wears away.
Unlike arthritis affecting the main shoulder joint (glenohumeral arthritis), AC joint arthritis usually causes localised pain over the top of the shoulder, particularly during cross-body movements or activities such as bench pressing, push-ups or reaching across the chest.
Many patients improve with non-surgical treatment, while surgery is reserved for persistent symptoms that do not respond to appropriate rehabilitation.
What is the AC Joint?
The acromioclavicular (AC) joint is the small joint where the collarbone meets the acromion, part of the shoulder blade.
Although it is much smaller than the main shoulder joint, it plays an important role by:
- Allowing normal shoulder movement
- Transferring force between the arm and trunk
- Helping the shoulder blade move during overhead activities
Over time, the cartilage covering the joint surfaces may wear down, leading to arthritis.
AC joint arthritis occurs when the cartilage within the joint gradually wears away.
AC Joint Arthritis vs Shoulder Arthritis: What’s the Difference?
| AC Joint Arthritis | Glenohumeral (Shoulder) Arthritis |
|---|---|
| Small joint at the top of the shoulder | Main ball-and-socket shoulder joint |
| Pain over the top of the shoulder | Deep shoulder pain |
| Worse with cross-body movements and bench press | Pain and stiffness with many shoulder movements |
| Usually preserves overall shoulder motion | Often causes significant loss of shoulder motion |
What Causes AC Joint Arthritis?
The condition may develop because of:
- Age-related wear and tear
- Previous AC joint injury or separation
- Heavy weight training
- Repetitive overhead activities
- Manual work
- Previous fractures involving the shoulder
Patients who have sustained an AC joint separation may develop arthritis years later.
Symptoms
Patients commonly report:
- Pain over the top of the shoulder
- Pain when reaching across the body
- Pain during bench press or push-ups
- Pain when sleeping on the affected side
- Local tenderness over the AC joint
- Clicking during shoulder movement
- Reduced strength because of pain
Unlike rotator cuff disorders, the pain is usually well localised to the top of the shoulder.
Pain is typically felt directly over the top of the shoulder and may worsen when reaching across the body.
How is AC Joint Arthritis Diagnosed?
Diagnosis begins with a clinical assessment.
Your orthopaedic surgeon will evaluate:
- The location of pain
- Shoulder movement
- Tenderness over the AC joint
- Cross-body adduction test
- Rotator cuff strength
- Associated shoulder conditions
Because several shoulder problems can produce similar symptoms, diagnosis is based on the overall clinical picture rather than imaging alone.
Imaging
X-rays
X-rays commonly demonstrate:
- Joint space narrowing
- Bone spurs (osteophytes)
- Joint degeneration
- Cysts within the bone
These changes become more common with age and do not always cause symptoms.
Ultrasound
Ultrasound can identify:
- Joint inflammation
- Associated rotator cuff pathology
- Fluid around the joint
It also allows ultrasound-guided AC joint injections, which may be used for both diagnosis and treatment.
MRI
MRI is useful when:
- Rotator cuff disease is suspected
- Symptoms are not explained by X-rays alone
- Surgery is being considered
MRI also evaluates the surrounding tendons, labrum and cartilage.
Does Every Arthritic AC Joint Cause Pain?
No.
Many people have arthritis visible on X-rays or MRI without any symptoms.
Treatment is based on:
- Your symptoms
- Clinical examination
- Functional limitations
rather than imaging findings alone.
Non-Surgical Treatment
Most patients improve without surgery.
Treatment may include:
- Activity modification
- Physiotherapy
- Anti-inflammatory medication
- Ice during painful flare-ups
- Ultrasound-guided corticosteroid injection into the AC joint when appropriate
Exercises are aimed at maintaining shoulder function while reducing stress across the joint.
When is Surgery Recommended?
Surgery may be considered when:
- Pain persists despite appropriate rehabilitation
- Symptoms significantly affect work, sport or daily activities
- Non-surgical treatment has been unsuccessful
- The AC joint is confirmed as the primary source of pain
The decision is based on symptoms and function rather than the severity of arthritis on imaging.
Surgical Treatment
The most common operation is arthroscopic distal clavicle excision, also known as the Mumford procedure.
During surgery, a small portion of the end of the collarbone is removed, eliminating painful contact between the arthritic joint surfaces while preserving shoulder function.
When other shoulder problems such as a rotator cuff tear are present, they can often be treated during the same operation.
Recovery
Recovery depends on whether other procedures are performed at the same time.
Typical recovery includes:
| Activity | Approximate Time |
|---|---|
| Sling | 1–2 weeks |
| Desk work | 1–2 weeks |
| Driving | 2–4 weeks |
| Physiotherapy | Begins early |
| Strengthening | 6–12 weeks |
| Return to sport | 2–4 months |
Frequently Asked Questions
Is AC joint arthritis the same as frozen shoulder?
No.
Frozen shoulder causes stiffness of the entire shoulder, whereas AC joint arthritis causes pain that is usually localised to the top of the shoulder without marked stiffness.
Why does bench pressing hurt?
Bench press places significant stress across the AC joint. Patients with AC joint arthritis commonly experience pain during the lowering phase of the exercise or when pushing the weight away from the chest.
Will I need surgery?
Most patients improve with non-surgical treatment. Surgery is generally reserved for persistent symptoms that continue despite rehabilitation and appropriate activity modification.
What is a distal clavicle excision?
A distal clavicle excision (Mumford procedure) involves removing a small portion of the end of the collarbone to eliminate painful contact within the arthritic AC joint while maintaining normal shoulder function.
Why Choose Dr Puah Ken Lee?
Dr Puah Ken Lee is an orthopaedic surgeon in Singapore with a practice focused on shoulder, elbow and sports injuries. He has experience managing both traumatic and degenerative conditions affecting the acromioclavicular joint. Treatment is tailored to the individual’s symptoms and functional goals, with surgery considered only when non-surgical measures have not provided sufficient relief.
Related Conditions
Primary cluster
- AC Joint Injury
- Shoulder Pain
- Shoulder Impingement Syndrome
- Rotator Cuff Tendinopathy
- Rotator Cuff Tear
- Shoulder Arthritis
Procedures
- Ultrasound-guided Shoulder Injections
- Shoulder Surgery
- Distal Clavicle Excision
Patient resources
For a full overview of shoulder conditions, visit Shoulder Specialist Singapore
Dr Puah is regularly invited to teach shoulder surgery internationally
Specialist Care for Shoulder Injuries in Singapore
Dr Puah is an orthopaedic surgeon specialising in shoulder, elbow and sports injuries. He provides personalised care tailored to each patient’s condition and activity level.
Consultations are available at Mount Elizabeth Novena.
If you are experiencing shoulder pain that is affecting your daily life or sports, early assessment can help guide appropriate treatment.
Book a consultation or contact the clinic to discuss your condition.
Book a Consultation
Book a consultation or contact the clinic via WhatsApp to get started
Book a consultation at 360 Orthopaedics, Mount Elizabeth Novena
Acromioclavicular joint arthritis is common but treatable. Early diagnosis and appropriate management can improve outcomes and prevent long-term problems.
Dr Puah Ken Lee is an orthopaedic surgeon in Singapore specialising in shoulder, elbow and sports injuries at 360 Orthopaedics, Mount Elizabeth Novena. Patients with persistent shoulder pain or stiffness are encouraged to seek specialist evaluation.