Condition
Shoulder arthritis
Shoulder arthritis is the wearing down of the cartilage on the ball or socket of the shoulder. As the cartilage wears away, the underlying bone becomes exposed, the joint stiffens, and pain progresses. Most early arthritis is managed without surgery; advanced arthritis is treated with shoulder replacement.
Anatomy
The cartilage that lines the joint
The shoulder is a ball-and-socket joint. The ball (the humeral head) and the socket (the glenoid) are both lined with a layer of articular cartilage. The cartilage is smooth and slippery, which lets the joint move freely with very little friction.
The cartilage has limited blood supply and very little capacity to repair itself. Once cartilage damage starts, it tends to progress over years.
Pathology
What happens in arthritis
Arthritis is a process of cartilage damage and the body's response to it. As the cartilage wears thin, several changes develop together.
- Cartilage thinning. The smooth gliding surface becomes rough and eventually wears through to the underlying bone.
- Bone-on-bone contact. Once cartilage is lost, the bone surfaces grind on each other, which is painful.
- Osteophytes. Bony spurs develop around the rim of the joint as the body tries to spread load. They limit motion and can cause additional pain.
- Capsular contracture. The joint capsule shrinks over time, which is part of why an arthritic shoulder feels stiff as well as sore.
- Glenoid bone changes. The socket can wear unevenly. In some patients, the humeral head rides forward or backward as the socket wears, which is important for surgical planning.
Causes
Why shoulder arthritis develops
Shoulder arthritis can be primary, where the cause is not known, or secondary, where it follows another condition or injury.
- Primary osteoarthritis. Wear-and-tear arthritis with no specific cause, usually in patients in their 60s and older.
- Post-traumatic arthritis. Damage to the cartilage during a fracture or dislocation can lead to arthritis years or decades later.
- Rotator cuff arthropathy. A long-standing massive cuff tear allows the humeral head to ride upwards and wear against the undersurface of the acromion. Important for surgical planning because reverse shoulder replacement, not anatomic, is the right operation.
- Inflammatory arthritis. Conditions like rheumatoid arthritis attack the joint lining and the cartilage directly.
- Avascular necrosis (AVN). Loss of blood supply to the humeral head causes the bone to collapse, which leads to arthritis.
- Post-instability arthritis. Cartilage damage from recurrent dislocations can lead to arthritis later in life.
Cuff tear arthropathy
When the rotator cuff is part of the picture
Cuff tear arthropathy is a specific pattern of shoulder arthritis that develops over years when a large rotator cuff tear is left unrepaired. It is the classic indication for reverse shoulder replacement and an important pattern to recognise because it changes the surgical plan.
When the cuff is intact, the ball stays low and slightly forward in the socket and the deltoid muscle can lift the arm efficiently. When the cuff is torn for years and not repaired, this centring force is lost. The deltoid pulls the ball upwards under the acromion. Over time the head of the humerus grinds against the under-surface of the acromion and the cartilage on both sides of the joint wears away.
On x-ray, this produces a recognisable pattern of high-riding humeral head, narrowing of the acromiohumeral interval, erosion of the under-surface of the acromion, and joint narrowing. MRI confirms the chronic, retracted cuff tear and shows poor muscle quality with significant fatty infiltration of the supraspinatus and infraspinatus.
Patients are typically older and describe both deep aching pain and significant loss of function. The classic finding is a shoulder that can be passively lifted overhead but cannot hold the arm there or actively lift it from the side. This pattern is sometimes called a pseudoparalytic shoulder.
An anatomic shoulder replacement relies on a working rotator cuff to function and would loosen quickly in this setting. A reverse shoulder replacement inverts the joint mechanics so the deltoid can lift the arm independently of the cuff. For most patients with cuff tear arthropathy, reverse replacement is the operation that reliably restores function. Read more about reverse shoulder replacement.
Symptoms
How shoulder arthritis feels
The cardinal symptoms are pain and progressive stiffness. The pain is usually a deep ache, often felt in the shoulder itself but sometimes referred down the upper arm.
Patients commonly describe pain at night, pain with overhead activity, and difficulty doing tasks like reaching behind their back to dress, putting on a seatbelt, or reaching into the back seat of the car.
Crepitus, a grating or clicking sensation in the shoulder during movement, is common in advanced arthritis and reflects the roughened joint surfaces.
The condition usually progresses gradually over years. A sudden worsening is unusual and should prompt a review for another cause.
Diagnosis
How shoulder arthritis is diagnosed
Diagnosis is based on history, examination, and imaging.
- X-rays. Usually diagnostic. AP, outlet, and axillary views show joint space narrowing, osteophytes, and the pattern of wear.
- MRI. Used when there is concern about associated rotator cuff damage or to distinguish arthritis from inflammatory or AVN-related causes.
- CT scan. Important for surgical planning when shoulder replacement is being considered. CT shows glenoid bone wear and bone stock in detail and is used to plan the orientation of implants.
- Blood tests. Sometimes ordered to screen for inflammatory or rheumatoid causes, particularly if the picture is atypical.
Treatment
Treatment options for shoulder arthritis
The aim of treatment is to control pain, maintain function, and replace the joint when those measures stop working. Treatment is usually stepped, starting with the least invasive options.
- Activity modification. Avoiding the positions and activities that flare the joint, while keeping moving. A motion-rich routine like a heated pool program can help.
- Physiotherapy. Maintenance of motion and rotator-cuff strength. Will not reverse the arthritis but helps with symptoms.
- Anti-inflammatory medication and analgesia. Paracetamol and an anti-inflammatory if appropriate, sometimes combined with stronger analgesia for short periods.
- Corticosteroid injection. An intra-articular injection can give months of pain relief. Effective at delaying surgery in many patients.
- Anatomic shoulder replacement. For arthritis with an intact rotator cuff and reasonable bone stock. The arthritic surfaces are resurfaced with anatomic implants.
- Reverse shoulder replacement. For arthritis combined with rotator cuff insufficiency, or for cuff-tear arthropathy. The reverse design changes the joint mechanics so the deltoid can lift the arm without needing the cuff.
Recovery
Recovery from shoulder replacement
The recovery from an anatomic shoulder replacement is much slower than a reverse shoulder replacement, because the rotator cuff tendons are repaired after an anatomic shoulder replacement. A sling is worn for the first six weeks following an anatomic replacement, but only two weeks after a reverse shoulder replacement. Passive exercises start within the first day or two under physiotherapy guidance. Active movement out of the sling progresses when the sling is removed (at two weeks or six weeks, depending on the surgery), with strengthening from around two to three months.
Most patients can drive at two to six weeks (once they are out of the sling) and have safe two-handed control of the steering wheel. Office work is usually possible within two to four weeks; manual work is later.
Pain relief from the arthritis is usually noticed quickly, often before strength has returned. Strength and range of motion continue to improve up to two years post replacement.
Complications and risks
Risks of shoulder replacement
Shoulder replacement is a major operation. The specific risks depend on the type of replacement, the patient's general health, and the bone quality. The general risks include (but are not limited to):
- Infection. Uncommon but serious. May require further surgery and a prolonged course of antibiotics.
- Dislocation. The new joint can come out of alignment, particularly in the early post-operative period.
- Loosening. The most common reason for revision in the long term.
- Nerve injury. Stretch on the brachial plexus is uncommon and usually recovers.
- Complex regional pain syndrome (CRPS). A rare condition that causes pain and stiffness in the hand.
- Fracture. The humerus or scapula can fracture during or after surgery, particularly with poor bone quality.
- Rotator cuff tears. An anatomic shoulder replacement depends on an intact rotator cuff to function properly.
- Anaesthetic complications. Discussed separately with the anaesthetist before surgery.
- DVT. Uncommon with upper-limb surgery but not zero.
Procedure-specific risks for reverse shoulder replacement are covered in detail on its dedicated procedure page.
FAQ
Frequently asked questions
- How is shoulder arthritis diagnosed?
- Diagnosis is based on history, examination, and imaging. Plain x-rays are usually diagnostic, showing joint-space narrowing, osteophytes, and the pattern of wear. MRI is added when there is concern about associated rotator cuff damage. CT is used for surgical planning when shoulder replacement is being considered.
- What is cuff tear arthropathy and how is it different from regular arthritis?
- Cuff tear arthropathy is a specific pattern of arthritis that develops when a long-standing rotator cuff tear allows the ball of the shoulder to ride upwards under the bony arch. Over time the head of the humerus grinds against the under-surface of the acromion and the cartilage on both sides wears away. The two conditions look different on x-ray, behave differently, and need different surgical solutions. Cuff tear arthropathy is the classic indication for reverse shoulder replacement.
- When is shoulder replacement indicated?
- Shoulder replacement is considered when arthritis pain and stiffness limit function, when the joint space is significantly narrowed on imaging, and when non-operative treatment (physiotherapy, anti-inflammatories, corticosteroid injections) has not provided sufficient relief. The choice between anatomic and reverse replacement depends on the rotator cuff and the bone stock.
- What is the difference between anatomic and reverse shoulder replacement?
- Anatomic shoulder replacement preserves the natural ball-and-socket relationship and relies on a working rotator cuff to lift the arm. It is used for arthritis with an intact cuff. Reverse replacement inverts the joint mechanics, putting the ball on the socket side and the cup on the humeral side, which lets the deltoid lift the arm without needing the cuff. It is used when the cuff is gone or unrepairable, and is the right operation for cuff tear arthropathy.
- How long does a shoulder replacement last?
- Modern shoulder replacements perform well over many years. The Comprehensive humeral stem and Comprehensive Reverse glenoid combination, which Dr Piper uses, has a 10-year cumulative revision rate of 3.4 percent (AOA NJRR 2025). Most patients have a single, lasting replacement.
- Can shoulder arthritis be treated without surgery?
- Yes, particularly in the earlier stages. Non-operative options include activity modification, physiotherapy, anti-inflammatories and analgesia, and intra-articular corticosteroid injections. These can manage symptoms for months to years, and many patients delay or avoid surgery entirely.
References
- Australian Orthopaedic Association National Joint Replacement Registry. Hip, Knee and Shoulder Arthroplasty: 2025 Annual Report — Shoulder Replacement. Adelaide: AOA; 2025. Tables ST1, ST6, ST78.
- Bacle G, et al. Long-term outcomes of reverse total shoulder arthroplasty: a follow-up of a previous study. J Bone Joint Surg Am. 2017;99(6):454-461.
Concerned about shoulder arthritis?
Book an appointment with Dr Piper
Consultations at Lakeview Private Hospital, Norwest. Bring a referral, recent imaging, and a list of treatments you have tried.