This page is intended for educational purposes. If you would like to book an appointment or need support with acromio-clavicular (AC) joint, please get in touch with Physio Soton Clinic in Eastleigh, near Southampton.
The acromioclavicular joint (ACJ) is a small joint located at the top of the shoulder where the acromion of the scapula meets the clavicle. ACJ arthritis, also known as degenerative osteoarthritis of the AC joint, occurs when the cartilage within this joint wears down over time, leading to pain, inflammation, and restricted shoulder movement. It is more common in adults over 40 and in individuals with a history of shoulder trauma or repetitive overhead activity.
Common symptoms of ACJ arthritis include:
Pain at the top of the shoulder, often exacerbated by lifting the arm overhead or crossing the arm across the chest
Tenderness directly over the AC joint
Swelling or a bony prominence at the joint
Clicking or grinding sensations during shoulder movement
Weakness or limited range of motion
Diagnosis is based on:
Clinical examination (palpation, cross-arm adduction test)
Imaging:
X-ray: shows joint space narrowing, osteophytes, or bone spurs
Ultrasound: can assess inflammation and guide interventions
MRI: used if other shoulder pathologies are suspected
Treatment depends on severity and response to conservative management.
Activity modification
Physical therapy for shoulder strengthening
NSAIDs for pain and inflammation
Ultrasound guidance improves accuracy of injections into the small AC joint and enhances treatment effectiveness while reducing complications. Common injectable therapies include:
Corticosteroid Injection
Reduces inflammation and pain in the joint
Provides rapid symptomatic relief, often lasting weeks to months
Typically combined with activity modification and physical therapy
Prolotherapy
Involves injection of an irritant solution (commonly dextrose) to stimulate the body’s natural healing response
Promotes strengthening of ligaments and joint stability
May reduce chronic pain and improve function over multiple sessions
Hyaluronic Acid Injection
Acts as a lubricant and shock absorber in the joint
Can reduce pain and improve mobility in degenerative arthritis
May be considered when corticosteroids are ineffective or contraindicated
Ultrasound-guided injection involves:
Positioning the patient with the shoulder exposed
Using a high-frequency ultrasound probe to visualize the AC joint
Guiding a needle directly into the joint space for precise delivery of medication
Confirming correct placement with real-time imaging
Most patients experience significant pain relief and improved function after appropriate injections combined with rehabilitation. Surgery, such as distal clavicle resection, is reserved for cases unresponsive to conservative and injection therapies.
AC joint arthritis is wear and tear of the small joint at the top of the shoulder where the collarbone meets the shoulder blade. The cartilage gradually thins, leading to pain, stiffness, and inflammation.
Common causes include:
Natural age-related degeneration
Previous shoulder injury or separation
Repetitive overhead activities (sports, manual work, gym training)
Heavy weightlifting over many years
Patients commonly notice:
Pain on the very top of the shoulder
Pain when reaching across the body (e.g., fastening a seatbelt)
Discomfort with overhead lifting
Tenderness when pressing directly on the joint
Clicking or grinding sensations
Diagnosis usually involves:
Clinical shoulder examination
X-ray imaging to confirm arthritis
Ultrasound assessment (often used if injection treatment is planned)
Sometimes MRI is requested if other shoulder problems are suspected.
This is a procedure where a clinician uses real-time ultrasound imaging to guide a needle precisely into the AC joint to deliver medication safely and accurately.
Ultrasound guidance improves accuracy and reduces the chance of injecting surrounding tissues.
An injection may be recommended if:
Pain has not improved with physiotherapy or medication
The diagnosis needs confirmation (diagnostic injection)
Pain is limiting sleep, work, or exercise
You want to delay or avoid surgery
Most commonly used treatment
Reduces inflammation inside the joint
Often provides rapid pain relief
Relief may last weeks to several months
Uses a dextrose solution to stimulate healing
Aims to strengthen surrounding ligaments and joint support
Typically performed as a series of treatments
Often considered for chronic or recurrent pain
Acts as a lubricant and shock absorber
May improve joint movement and reduce pain
Sometimes used when steroid injections are unsuitable or short-lived
Most patients experience only mild discomfort.
Local anaesthetic is usually used, and ultrasound guidance allows a very precise and quick injection.
Pain usually settles within 24–48 hours.
The injection itself typically takes:
5–10 minutes for the procedure
About 20–30 minutes total appointment time
Local anaesthetic relief → within hours (temporary)
Steroid benefit → usually within 3–10 days
Prolotherapy → gradual improvement over weeks
Hyaluronic acid → often improves over several weeks
This varies by patient:
Steroid: weeks to months
Prolotherapy: longer-term improvement after a course
Hyaluronic acid: several months in some patients
Some patients require repeat injections.
Injection risks are low but can include:
Temporary pain flare after injection
Infection (very rare)
Skin thinning or colour change (with steroid)
Temporary numbness
Ultrasound guidance helps minimise these risks.
Typical advice:
Rest the shoulder for 24–48 hours
Avoid heavy lifting for several days
Start or continue physiotherapy as advised
Gradually return to normal activities
Yes — injections reduce pain, but physiotherapy improves strength, mechanics, and long-term outcomes.
Best results usually come from injection + rehabilitation.
Surgery is usually only discussed if:
Pain persists despite physiotherapy and injections
Symptoms significantly limit daily function
Imaging confirms severe joint degeneration