Procedure
Anatomic shoulder replacement
Resurfacing of the worn ball and socket of the shoulder with anatomic implants. Used for shoulder arthritis where the rotator cuff is intact and the bone stock is reasonable.
Anatomic versus reverse
Why the rotator cuff matters
Two main types of shoulder replacement are used in Australia. The right one for any patient depends on whether the rotator cuff is working.
Anatomic shoulder replacement preserves the natural ball-and-socket relationship. A metal ball is placed on the humeral side and a polyethylene socket on the glenoid side. The shoulder still relies on the rotator cuff to lift the arm, so it works well only when the cuff is intact and functioning.
Reverse shoulder replacement inverts the joint mechanics. The ball is placed on the socket side and the cup on the humeral side, which lets the deltoid lift the arm without needing the rotator cuff. Used when the cuff is gone or unrepairable.
The choice between the two is the central decision in shoulder-replacement planning. CT imaging and a careful rotator-cuff assessment drive that decision.
Indications
When anatomic replacement is the right operation
- Primary osteoarthritis of the shoulder in younger patients with reasonable preservation of the rotator cuff and bone stock.
- Post-traumatic arthritis after a fracture has healed and the cuff is functioning.
- Avascular necrosis (AVN) of the humeral head with secondary arthritis.
- Inflammatory arthritis with an intact cuff.
When the rotator cuff is torn or non-functioning, when there is cuff-tear arthropathy, or when the glenoid bone has worn so far that an anatomic socket cannot be securely fixed, reverse shoulder replacement is the better option.
The procedure
What happens in the operating theatre
The procedure is performed under general anaesthetic, usually with a regional nerve block to help with post-operative pain control. The patient is positioned in a beach-chair position, and the operative arm is prepped and draped free.
The shoulder is approached through the deltopectoral interval at the front of the shoulder. The subscapularis tendon is taken down to access the joint. The arthritic humeral head is resected, and the canal of the humerus is prepared. A stem with an anatomic-shaped metal ball is implanted on the humeral side.
The glenoid (socket side) is then prepared. A polyethylene socket is fixed to the bone, usually with cement. The components are reduced, the soft tissues are repaired, and the wound is closed in layers. A sling is applied at the end of the procedure.
Operative time is typically 90 to 120 minutes. Most patients stay in hospital for two nights.
Recovery
What recovery looks like
Recovery is similar to a rotator cuff repair. It takes longer than a reverse shoulder replacement because the rotator cuff repair (subscapularis tendon) is critical. A sling is worn for the first six weeks to protect the subscapularis repair. Passive exercises start within the first day or two under physiotherapy guidance.
Active movement out of the sling progresses through weeks six to twelve. Strengthening is introduced from around three months. Most patients can drive at six weeks once out of the sling and with safe two-handed control of the steering wheel, return to office work within two to four weeks, and return to manual work later depending on the demands.
Pain relief from the arthritis is usually noticed within the first three months. Strength and range of motion continue to improve over six to twelve months.
Complications and risks
What can go wrong
Anatomic shoulder replacement is a major operation. The general risks include (but are not limited to):
- Infection. Uncommon but serious. May require further surgery and a prolonged course of antibiotics.
- Subscapularis failure. The subscapularis tendon is taken down at the start of the procedure and repaired at the end. Failure of that repair is an issue specific to anatomic replacement and can cause weakness and instability.
- Loosening of the components. The most common reason for revision in the long term. The glenoid component is typically the first to loosen.
- Fracture. The bone may break around the prosthesis (usually as a result of an injury) and cause the prosthesis to loosen. Fractures around a prosthesis usually require surgery to fix the fracture or replace the anatomic shoulder replacement with a reverse prosthesis.
- Late rotator cuff failure. The rotator cuff can fail years after an anatomic replacement, leading to symptoms that may need conversion to a reverse replacement.
- Dislocation. The new joint can come out of alignment, particularly in the early post-operative period.
- 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.
- Anaesthetic complications. Discussed separately with the anaesthetist before surgery.
- DVT. Uncommon with upper-limb surgery but not zero.
FAQ
Frequently asked questions
- When is anatomic shoulder replacement chosen over reverse?
- Anatomic replacement is the right operation for young people with arthritis with an intact, functioning rotator cuff and reasonable bone stock. The natural ball-and-socket relationship is preserved. When the cuff is gone, irreparable, or non-functioning, or when the glenoid bone has worn so far that an anatomic socket cannot be securely fixed, reverse shoulder replacement is the better option.
- How long does an anatomic shoulder replacement last?
- Modern anatomic shoulder replacements perform well over many years. Loosening of the components is the most common reason for revision in the long term, with the glenoid component typically the first to loosen. Late rotator cuff failure can also occur and may require conversion to a reverse replacement.
- How long is recovery from anatomic shoulder replacement?
- A sling is worn for six weeks. Passive exercises start within the first day or two. Active movement progresses through weeks six to twelve. Strengthening from around three months. Most patients can drive at six weeks once out of the sling and with safe two-handed control of the steering wheel, and return to office work within two to four weeks. Strength and range of motion continue to improve over six to twelve months.
- Will I have full range of motion after the surgery?
- Most patients regain a near-normal range of motion, particularly in the early years after surgery. Pain relief from the arthritis is usually noticed within the first three months. End-range movement may be slightly less than a normal shoulder, but day-to-day activities, work, and most sport are typically possible.
- How long does the operation take?
- Operative time is typically 90 to 120 minutes. Most patients stay in hospital for two nights. The procedure is performed under general anaesthetic, often combined with a regional nerve block to help with post-operative pain control.
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