Are acromioplasty and AC joint resection the same operation?

They are two related but distinct procedures of the upper shoulder, often performed through the same arthroscopic setup but addressing different problems. Acromioplasty (subacromial decompression) trims the undersurface of the acromion to widen the space above the rotator cuff. AC joint resection (distal clavicle excision) removes a small portion of the outer end of the clavicle to treat acromioclavicular joint arthritis. They are sometimes done together when both pathologies coexist.

When is acromioplasty appropriate as a stand-alone operation?

The role of acromioplasty as a stand-alone treatment for shoulder pain has narrowed in recent years. The CSAW trial and subsequent evidence have raised questions about benefit when non-operative treatment has not been completed. Most acromioplasties Dr Piper performs are alongside a rotator cuff repair, where trimming the under-surface of the acromion creates clear space for the repaired tendon to heal without impingement. Stand-alone acromioplasty is reserved for selected cases with clear bursal-side pathology and a thorough non-operative trial.

When is AC joint resection appropriate?

AC joint resection is offered for symptomatic AC joint arthritis that has not responded to corticosteroid injection and activity modification. The diagnosis is supported by tenderness directly over the AC joint, pain on cross-body adduction, and short-term symptom relief from a diagnostic AC joint injection. Imaging shows joint-space narrowing and osteophytes at the AC joint.

Will the bone grow back?

Some bony regrowth on the under-surface of the acromion is common over time, but only rarely re-creates the impingement to a degree that needs further surgery. After AC joint resection the gap is usually maintained by scar tissue. Recurrence of AC arthritis is uncommon. The supporting ligaments around the AC joint are deliberately preserved during resection so that joint stability is not affected.

Procedure

Acromioplasty and AC joint resection

Two arthroscopic procedures of the upper shoulder, often performed through the same setup. Acromioplasty (subacromial decompression) addresses impingement of the rotator cuff. AC joint resection (distal clavicle excision) addresses arthritis of the acromioclavicular joint at the bony point on top of the shoulder.

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Indications

When each operation is indicated

The two procedures address different problems. Indications are considered separately for each.

Acromioplasty (subacromial decompression)

The role of acromioplasty as a stand-alone treatment for shoulder pain has narrowed in the past decade. The CSAW trial and the subsequent literature raised real questions about benefit when non-operative treatment had not been thoroughly completed first. Today acromioplasty is most often performed as an adjunct to another operation rather than on its own.

Alongside rotator cuff repair. The most common setting. Trimming the under-surface of the acromion creates a clear path for the repaired cuff to heal without impingement against overlying bone.
Selected impingement syndrome. In carefully selected patients with clear bursal-side pathology, an obvious anatomic acromial spur, and a thorough non-operative trial of physiotherapy, activity modification, and corticosteroid injection that has failed to settle the symptoms.
Calcific tendinopathy. Occasionally combined with arthroscopic excision of a calcific deposit when the deposit has not responded to non-operative treatment, including ultrasound-guided needling.

AC joint resection (distal clavicle excision)

AC joint resection has clearer indications and a more consistent track record than stand-alone acromioplasty.

Symptomatic AC joint arthritis. Tenderness directly over the AC joint, pain on cross-body adduction, and pain that is reliably reduced by a diagnostic AC joint injection. Imaging shows joint-space narrowing and osteophytes.
Failed non-operative treatment. Activity modification, simple analgesia, physiotherapy, and corticosteroid injections to the AC joint.
Os acromiale or congenital variants. Occasionally indicated for symptomatic os acromiale or associated AC joint pathology that is contributing to upper shoulder pain.
As an adjunct to rotator cuff repair. When the AC joint is symptomatic and contributing to the overall picture in a patient otherwise heading for cuff repair.

How it works

What each procedure does

Acromioplasty reshapes the under-surface of the acromion. The acromion is the bony arch that sits over the rotator cuff. Some shapes of acromion, and some patterns of bony spur on the under-surface, narrow the subacromial space and contact the bursa or rotator cuff during overhead movement. Removing a small amount of bone from the under-surface widens the space and removes that contact.

AC joint resection removes around 5 to 8 millimetres of bone from the lateral end of the clavicle, eliminating the bone-on-bone contact at the acromioclavicular joint. The supporting AC and coracoclavicular ligaments are deliberately preserved to maintain joint stability. The gap fills with scar tissue and remains a functional non-arthritic interface.

When the two procedures are done together, they share the same arthroscopic portals and instruments. The acromioplasty is performed first to clear the under-surface of the acromion, then the AC joint is approached from below and the distal clavicle resected.

The procedure

What happens in the operating theatre

Both procedures are performed arthroscopically under general anaesthetic, often with a regional nerve block to help with post-operative pain control. The patient is positioned in the beach-chair position, and the operative arm is prepped and draped free.

Two or three small portal incisions are made around the shoulder. The arthroscope is placed first into the glenohumeral joint to inspect the rotator cuff and intra-articular structures. The camera is then redirected into the subacromial space.

For acromioplasty, the bursa is cleared so the under-surface of the acromion is visible. A burr is used to trim the under-surface back to a flat profile. The amount of bone removed is judged by direct visualisation and by clearance relative to the rotator cuff.

For AC joint resection, the inferior capsule of the AC joint is opened and the distal clavicle is exposed. A burr is used to remove the lateral end of the clavicle, again under direct visualisation. The acromial side of the joint is preserved. The supporting ligaments are protected.

The portals are closed with absorbable sutures. A bulky dressing and a sling are applied. Most cases are a day case or a single overnight stay.

Recovery

What recovery looks like

When performed in isolation, recovery is brisk. The sling is worn for comfort for a few days. Range of motion exercises start straight away under physiotherapy guidance. Active use of the arm for everyday tasks progresses over the first two to four weeks.

Most patients return to office work within one to two weeks, driving by two weeks (once out of the sling and with safe two-handed control of the steering wheel), and to full unrestricted activity by six to eight weeks. Pain settles over a similar timeframe. Some discomfort with overhead movement during the first few weeks is expected and improves as the inflammation around the operative site resolves.

When acromioplasty is performed alongside a rotator cuff repair, recovery follows the rotator-cuff protocol: a sling for six weeks to protect the cuff repair, with passive motion in the early weeks and graduated active motion and strengthening over twelve weeks and beyond. The acromioplasty itself does not slow this timeline.

Complications and risks

What can go wrong

Both procedures are well established and complications are uncommon. The specific risks include (but are not limited to):

Persistent pain. The most important consideration. Some patients have ongoing shoulder pain after acromioplasty, which usually reflects inadequate pre-operative diagnosis or untreated associated pathology rather than the surgery itself. The same applies to AC joint resection if the AC joint was not the dominant pain generator.
Stiffness. A period of stiffness after surgery is common and improves with physiotherapy. Significant ongoing stiffness is uncommon and managed conservatively.
Inadequate or excessive resection. For acromioplasty, taking too little bone leaves residual contact, while taking too much can weaken the acromion. For AC resection, taking too little leaves residual bone-on-bone contact, while taking too much risks instability of the clavicle. Modern arthroscopic technique with direct visualisation reduces both risks.
Heterotopic bone formation. Bone re-growth at the acromial under-surface or the AC resection site can occur but rarely re-creates the original impingement.
Infection. Very uncommon with arthroscopic shoulder surgery.
Nerve injury. Rare. Stretch injuries to the brachial plexus from beach- chair positioning are uncommon and usually recover.
Complex regional pain syndrome (CRPS). A rare condition that causes pain and stiffness in the hand.
AC joint instability. Specific to AC joint resection. The supporting ligaments are preserved during the procedure to maintain stability. Loss of stability after isolated distal clavicle excision is uncommon.
Anaesthetic and medical complications. Discussed separately by the anaesthetist before surgery. The risk of DVT is low for upper-limb surgery.

FAQ

Frequently asked questions

Are acromioplasty and AC joint resection the same operation?: They are two related but distinct procedures of the upper shoulder, often performed through the same arthroscopic setup but addressing different problems. Acromioplasty (subacromial decompression) trims the undersurface of the acromion to widen the space above the rotator cuff. AC joint resection (distal clavicle excision) removes a small portion of the outer end of the clavicle to treat acromioclavicular joint arthritis. They are sometimes done together when both pathologies coexist.
When is acromioplasty appropriate as a stand-alone operation?: The role of acromioplasty as a stand-alone treatment for shoulder pain has narrowed in recent years. The CSAW trial and subsequent evidence have raised questions about benefit when non-operative treatment has not been completed. Most acromioplasties Dr Piper performs are alongside a rotator cuff repair, where trimming the under-surface of the acromion creates clear space for the repaired tendon to heal without impingement. Stand-alone acromioplasty is reserved for selected cases with clear bursal-side pathology and a thorough non-operative trial.
When is AC joint resection appropriate?: AC joint resection is offered for symptomatic AC joint arthritis that has not responded to corticosteroid injection and activity modification. The diagnosis is supported by tenderness directly over the AC joint, pain on cross-body adduction, and short-term symptom relief from a diagnostic AC joint injection. Imaging shows joint-space narrowing and osteophytes at the AC joint.
How quickly does recovery progress?: Recovery is brisk for both procedures when performed in isolation. A sling is worn for comfort for a few days. Range of motion exercises start straight away. Most patients return to office work within one to two weeks, driving by two weeks (once out of the sling and with safe two-handed control of the steering wheel), and full unrestricted activity by six to eight weeks. When acromioplasty is performed alongside a rotator cuff repair, recovery follows the rotator-cuff-repair protocol (six weeks in a sling, twelve-week graduated rehabilitation).
Will the bone grow back?: Some bony regrowth on the under-surface of the acromion is common over time, but only rarely re-creates the impingement to a degree that needs further surgery. After AC joint resection the gap is usually maintained by scar tissue. Recurrence of AC arthritis is uncommon. The supporting ligaments around the AC joint are deliberately preserved during resection so that joint stability is not affected.

References

Beard DJ, et al. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. Lancet. 2018;391(10118):329-338.

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Consultations at Lakeview Private Hospital, Norwest. Bring a referral and any imaging or injection records you have.

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