Beach Chair | Deltoid Split or Acromial Osteotomy | Axillary Nerve at Risk
- Beach-chair position with the arm free and draped to allow intra-operative manipulation.
- There is no true internervous plane - the deltoid is split in the line of its fibres (axillary nerve on both sides) or the acromion is osteotomized.
- The axillary nerve runs roughly 5 cm (range 3 to 7 cm) below the lateral acromion on the deep deltoid surface - this defines the deltoid-split safe zone.
- The suprascapular nerve tethers the cuff about 2 cm medial to the glenoid rim and limits lateral mobilization of a retracted supraspinatus.
- Deltoid origin reattachment is the critical step - deltoid dehiscence is a devastating, often uncorrectable complication.
- The extensile transacromial approach is largely historical, superseded by arthroscopy and mini-open repair for most cuff pathology.
When & Why
What it exposes. The superior approach reaches the shoulder joint from above, passing over the top of the acromion and through the deltoid. It gives direct access to the supraspinatus, the superior glenohumeral joint, the subacromial space, and the acromioclavicular region. Primary indications: - Open rotator cuff repair (historical) - particularly large or retracted tears needing direct superior access
- Acromioplasty and subacromial decompression when performed open
- Acromioclavicular joint procedures - distal clavicle excision (Mumford), AC reconstruction
- Selected proximal humeral and superior glenoid exposures where an anterior route is inadequate
- Tumour involving the superolateral shoulder girdle
- Suprascapular nerve decompression at the transverse scapular ligament (more often posterior or arthroscopic) Why the approach is now limited. Arthroscopic cuff repair, arthroscopic subacromial decompression, and mini-open deltoid-sparing techniques now provide equivalent or superior visualization with far less deltoid morbidity. The extensile transacromial approach, once standard for massive cuff tears, is reserved for the uncommon tear that cannot be mobilized or fixed arthroscopically, for selected revision work, or for tumour. Contraindications: - Pre-existing deltoid deficiency or detachment (no working muscle to split or repair)
- Anterior pathology better served by the deltopectoral approach
- Most degenerative cuff tears (arthroscopy is the standard of care) Alternative approaches: - Deltopectoral approach - the workhorse for anterior shoulder pathology (glenohumeral joint, subscapularis, arthroplasty); does not endanger the deltoid origin
- Anterolateral deltoid-split approach - a more limited split for subacromial work and certain proximal humeral fractures
- Posterior approach - for posterior glenoid, the infraspinatus, and the trapezius-deltoid internervous interval
- Arthroscopic repair - the modern default for cuff tears and subacromial decompression Position & landmarks. Beach-chair (semi-recumbent) is the standard position. The patient sits up roughly 60 to 70 degrees, the shoulder is brought off the edge of the table, and the arm is left free so an assistant can apply traction, rotation, and flexion-extension as needed to deliver the cuff into the wound. A padded headrest, secure torso strapping, and protection of all pressure points (especially the contralateral ulnar nerve and the sacrum) are mandatory; a towel or bolster under the scapula can tilt the shoulder forward. Lateral decubitus is an alternative for some posterosuperior work, but the beach-chair set-up gives the best superior access and is the position examiners expect. Beach-chair safety checklist: - Confirm haemodynamic stability - the seated position can precipitate hypotension; communicate with anaesthesia
- Pad all pressure points and secure the torso to prevent sliding
- Protect the head and neck in a neutral, supported position
- Position the contralateral arm carefully to avoid brachial plexus stretch
- Confirm C-arm access if intra-operative imaging is anticipated
- Plan and rehearse cerebral perfusion considerations for prolonged seated surgery Surface landmarks to mark before draping: - Acromion - palpate its anterior, lateral, and posterior borders; the lateral border is the reference for the axillary-nerve measurement
- Acromioclavicular (AC) joint - the step-off between the distal clavicle and the acromion
- Distal clavicle - marks the anterosuperior boundary
- Coracoid process - anteroinferior reference; the saber-cut incision aims toward it
- Scapular spine - posterior boundary, origin of the posterior deltoid Incision planning. Mark the bony landmarks on the skin before draping so the incision can be centred precisely over the pathology. Review plain radiographs for acromial morphology (Bigliani type), acromiohumeral narrowing, proximal migration of the humeral head, and calcific deposits, and an MRI to characterize tear size, retraction, muscle atrophy, and fatty infiltration - the imaging determines whether the cuff is repairable and whether an extensile open route is justified.
| Variant | Incision Line | Best For | Deltoid Management |
|---|---|---|---|
| Superior deltoid-split | Longitudinal, in Langer lines over the acromion | Subacromial decompression, cuff repair | Split in line with fibres |
| Saber-cut / strap | Oblique, over the anterosuperior shoulder toward the coracoid | AC joint, anterosuperior work | Split or limited takedown |
| Transacromial | Crosses the acromion in the osteotomy plane | Massive or retracted cuff tears | Acromial osteotomy with deltoid reflection |
The Exposure
Work down through the deltoid over the top of the acromion, splitting the muscle in the line of its fibres to reach the subacromial bursa and the supraspinatus, or - for a massive retracted tear - osteotomizing the acromion and reflecting it with the deltoid. The defining teaching point is the dissection basis, not an internervous plane.
If the examiner asks for the internervous plane of the superior approach, the correct answer is that there is none. The deltoid is split within its own substance (axillary nerve on both sides), or the acromion is osteotomized and reflected with the deltoid. The trapezius-deltoid interval (spinal accessory nerve versus axillary nerve) is a true internervous plane, but it belongs to the posterior approach and is only relevant here when the deltoid origin is taken down from the acromion or scapular spine to enlarge the exposure. Say it out loud - do not invent a plane that does not exist.
Deltoid anatomy (the muscle you are splitting): | Feature | Detail | |---------|--------| | Origin | Lateral third of the clavicle, acromion, scapular spine | | Parts | Anterior (clavicular), middle (acromial), posterior (spinal) | | Insertion | Deltoid tuberosity of the humerus | | Nerve supply | Axillary nerve (C5, C6) | | Deep relation | Axillary nerve and posterior circumflex humeral artery run on its deep surface | What lies beneath. Below the deltoid lies the subacromial bursa, then the rotator cuff - chiefly the supraspinatus as it passes under the coracoacromial arch to its greater-tuberosity insertion. The coracoacromial arch (acromion, coracoacromial ligament, and AC joint) forms the roof over which the cuff glides. The suprascapular nerve enters the supraspinatus from its deep, medial surface, tethering the muscle. Coracoacromial arch and impingement. The arch is a primary restraint to superior migration of the humeral head, and its anterior undersurface is the site of mechanical impingement on the cuff. A hooked (type III) acromion, anteroinferior spurs, and AC joint osteophytes narrow this space. Reshaping the arch (acromioplasty) and decompressing the subacromial space are among the procedures the superior approach was built to perform.
Intra-operative photograph of the superior approach to the shoulder in the beach-chair position: a longitudinal incision over the acromion, the deltoid split in the line of its fibres with a stay suture at the distal apex of the split, retractors opening the subacromial space, and the supraspinatus tendon and its greater-tuberosity footprint exposed beneath the coracoacromial arch.
Context: A verified image is being sourced for this exposure.
Exposure sequence
- Mark the acromion, AC joint, and coracoid before draping.
- Make the chosen incision - superior longitudinal, saber-cut, or transacromial - through skin and subcutaneous tissue down to the deltoid fascia.
- Incise the deltoid fascia and split the deltoid in the line of its fibres, beginning at the acromion and extending distally.
- Stay within roughly 5 cm of the lateral acromial border to remain proximal to the axillary nerve.
- Place a stay suture at the distal apex of the split to prevent propagation into the nerve, and bluntly separate the fibres down to the subacromial bursa.
- Incise the bursa to expose the underlying supraspinatus and the anterosuperior cuff; debride hypertrophic bursa as needed.
- With the arm rotated, the cuff insertion on the greater tuberosity comes into view.
- For a massive, retracted tear, perform an acromial osteotomy (classically a sagittal or coronal cut).
- Mobilize a fragment of acromion together with its attached deltoid origin and reflect it, opening the superior joint and the retracted cuff directly; preserve the trapezius attachment to the bone fragment.
- After cuff repair, the osteotomy is reduced and fixed.
- When the AC joint is the target (e.g. distal clavicle excision), extend the incision anterosuperiorly over the joint, split or elevate the overlying deltoid, and resect the distal 1 to 2 cm of clavicle from above.
- If decompression is planned, remove the undersurface of the anterior acromion and any anteroinferior spurs with an osteotome or rongeur, preserving the deltoid origin on the superior acromial surface.
- To mobilize a retracted cuff, release the coracohumeral ligament and perform an anterior and posterior interval slide as needed, working gently so as not to place traction on the suprascapular nerve.
- Deliver the tendon to its footprint with the arm in slight flexion and rotation, and confirm a tension-free reduction before fixation.
- Prepare a bleeding bony bed at the greater-tuberosity footprint.
- Fix the tendon with transosseous sutures, suture anchors, or a combination, achieving secure tendon-to-bone contact.
- Confirm the repair is stable through a functional range of motion before closing.
| Variant | Dissection Basis | Plane Type | Exposure Gained |
|---|---|---|---|
| Deltoid split | Intramuscular, axillary nerve both sides | Not internervous | Supraspinatus, subacromial space |
| Transacromial | Acromial osteotomy with deltoid reflection | Not internervous | Supraspinatus and superior joint, massively retracted tears |
| Trapezius-deltoid takedown | Interval between trapezius and deltoid | True internervous (accessory vs axillary) | Scapular spine, supraspinous fossa, posterosuperior cuff |
The single most useful technical safeguard in the deltoid split is a stay suture at the distal apex of the split. It marks the limit of safe dissection and stops the split propagating distally into the axillary nerve during retraction.
Dangers & Extensions
The axillary nerve crosses the deep surface of the deltoid roughly 5 cm (range 3 to 7 cm) below the lateral border of the acromion, accompanied by the posterior circumflex humeral artery. Keep the deltoid split proximal to this, place a stay suture at the apex, and avoid self-retaining retractors that stretch the nerve. Axillary nerve injury weakens deltoid abduction and external rotation and numbs the regimental-badge area of the lateral upper arm.
Structures at risk, by layer
| Layer | Structure | Why at Risk | Protection |
|---|---|---|---|
| Deep to deltoid | Axillary nerve | Crosses deep deltoid about 5 cm below acromion | Stay split proximal; stay suture at apex; no over-retraction |
| Deep to deltoid | Posterior circumflex humeral artery | Runs with the axillary nerve | Stay subacromial, avoid deep distal dissection |
| Cuff mobilization | Suprascapular nerve | Tethers the cuff about 2 cm from glenoid rim | Mobilize gently; avoid forceful lateral traction of supraspinatus |
| AC region | Acromial branch of thoracoacromial artery | Crosses the AC joint | Coagulate during AC exposure |
| Origin takedown | Deltoid (denervation) | Risks devascularization or nerve injury | Repair meticulously to bone; avoid excessive stripping |
Two nerves to name. Examiners expect two nerves. The axillary nerve is at risk during the deltoid split and during subdeltoid dissection - it lies on the deep deltoid surface about 5 cm below the lateral acromion. The suprascapular nerve is at risk when the cuff is mobilized - it is tethered roughly 2 cm medial to the glenoid rim and limits how far a retracted supraspinatus can be pulled laterally. Most traction injuries are neurapraxic and recover, but suprascapular nerve injury denervates the supraspinatus and infraspinatus, compounding the very cuff deficiency the operation set out to treat; both are avoided by gentle technique. How to extend the approach: - Distally - continue the deltoid split down the humeral shaft, always respecting the axillary nerve safe zone; the split's distal limit is the nerve.
- Anteriorly - convert to a deltopectoral approach (useful when anterior glenoid or the lower subscapularis must be reached).
- Medially / posteriorly - toward the scapular spine and supraspinous fossa to expose the supraspinatus belly or the suprascapular notch, taking the deltoid origin off the scapular spine (the trapezius-deltoid interval); the suprascapular nerve and artery at the transverse scapular ligament are at risk here. Closure - the critical step. Meticulous repair of the deltoid origin is the single most important step. A dehisced deltoid after acromioplasty or transacromial osteotomy causes persistent weakness, deformity, and is notoriously difficult to salvage.
| Variant | Deltoid / Bone Repair | Fixation | Post-op Protection |
|---|---|---|---|
| Deltoid split | Close side-to-side over the bursa | Absorbable suture; secure stay suture | Sling, early passive motion |
| Origin takedown | Reattach deltoid to acromion | Heavy non-absorbable suture through bone tunnels or anchors | Sling or abduction pillow, protected active abduction |
| Transacromial | Reduce and fix acromial osteotomy | Tension-band wiring or screws | Protected until radiographic union |
Closure principles. Close the deltoid fascia, reapproximate subcutaneous tissue, and close skin. Apply a sling or abduction pillow to unload the repair, and restrict active abduction against resistance until healing - typically about six weeks. Post-operative rehabilitation: - 0 to 6 weeks: Sling or abduction pillow; passive and active-assisted motion only; protect the deltoid origin and any cuff repair; no active abduction against gravity.
- 6 to 12 weeks: Progress to active motion and gentle strengthening as the deltoid repair consolidates; confirm radiographic union of any acromial osteotomy.
- 12 weeks and beyond: Progressive resistance and functional rehabilitation; return to demand activity once strength and motion are restored. The rehabilitation timeline is dictated by the integrity of the deltoid repair and the cuff fixation. If an acromial osteotomy was performed, protect against active abduction and resistive loading until radiographic union is confirmed.
Procedures Through This Approach
- Open rotator cuff repair - supraspinatus and adjacent cuff, especially retracted tears (historical standard)
- Anterior acromioplasty / open subacromial decompression - removal of the anterior acromial prominence and bony spurs
- Distal clavicle excision (Mumford) - for AC joint arthrosis
- AC joint reconstruction - for AC dislocation
- Suprascapular nerve decompression - release of the transverse scapular ligament
- Selected proximal humeral and superior glenoid work, and tumour resection
Viva & Exam Focus
SUPERIORSUPERIOR - surgical steps
DELTOIDDELTOID - split safe zone
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 62-year-old presents with a painful, weak shoulder and an MRI showing a large, retracted supraspinatus tear. Describe how you would expose and repair it, including your approach.”
“Six weeks after an open cuff repair through a superior approach with an acromioplasty, a patient reports new shoulder weakness and a visible bulge on attempted abduction. Discuss your assessment.”
“Describe the internervous plane and the structures at risk in the superior approach to the shoulder.”
Position & Landmarks
- Beach-chair position, arm free for manipulation
- Landmarks: acromion, AC joint, distal clavicle, coracoid, scapular spine
- Variants: deltoid split, transacromial osteotomy, saber-cut
- Lateral acromial border is the reference for the axillary-nerve measurement
Internervous Plane
- NO true internervous plane
- Deltoid split = axillary nerve on both sides (intramuscular)
- Transacromial = acromial osteotomy with deltoid reflection
- Trapezius-deltoid interval is internervous but belongs to the posterior approach
Nerves at Risk
- Axillary nerve about 5 cm (3 to 7 cm) below the lateral acromion
- Suprascapular nerve about 2 cm medial to the glenoid rim
- Stay suture at the deltoid-split apex to protect the axillary nerve
- Do not over-retract the cuff (suprascapular nerve)
Dissection
- Split deltoid in line with fibres from the acromion down
- Stay within the 5 cm safe zone
- Open the subacromial bursa to reach the supraspinatus
- Osteotomize acromion for massive retracted tears (transacromial)
Closure (Critical)
- Deltoid split: close side-to-side, secure stay suture
- Origin takedown: reattach to acromion via bone tunnels or anchors
- Acromial osteotomy: tension-band or screw fixation
- Protect the repair in a sling or abduction pillow for about six weeks
Why It Is Historical
- Arthroscopy and mini-open repair have replaced it for most cuff disease
- Deltoid dehiscence and acromial nonunion are feared complications
- Reserve for selected massive or revision tears, or tumour
- Know it for the operative-surgery viva even if rarely performed
References
Guidelines, Registries & Global Practice Rotator cuff disease is among the most common upper-limb complaints worldwide, and its management is addressed by major orthopaedic bodies across examination systems (advanced orthopaedic practice and advanced orthopaedic practice, DNB and MS, MRCS, SICOT). The superior and transacromial approaches are taught as historical and selective exposure techniques rather than the workhorse for degenerative cuff tears. Side-by-side principles (where guidance converges): - The AAOS appropriate-use criteria for rotator cuff symptoms acknowledge arthroscopic and mini-open repair as mainstream options, with open transacromial exposure reserved for selected massive or revision tears.
- BOA and BOAST principles emphasize careful patient selection, deltoid-sparing techniques where possible, and the avoidance of deltoid dehiscence.
- Across regions, the trend is the same: arthroscopic cuff repair and subacromial decompression have displaced the extensile open superior approach, reducing deltoid morbidity. Global practice variation. In well-resourced settings, arthroscopy is the default for most cuff pathology; the open transacromial route survives only for the uncommon irreparable-looking tear that proves immobile arthroscopically. In resource-limited settings, an open deltoid-splitting repair remains a reasonable definitive option when arthroscopy is unavailable, with the same emphasis on protecting the axillary nerve and repairing the deltoid. Consent (globally applicable). Discuss deltoid weakness or dehiscence (the defining risk of this approach), axillary and suprascapular nerve injury, infection, stiffness, failure of cuff healing, and the possibility that an irreparable tear may need reconstruction (tendon transfer) or reverse arthroplasty.
For the Operative Surgery station, be ready to describe the superior approach systematically: beach-chair positioning, the absence of a true internervous plane, the deltoid split and its axillary-nerve safe zone, the transacromial osteotomy for massive tears, the two nerves at risk, and - above all - the principles of deltoid reattachment and why the approach is now largely historical.
Anterior Acromioplasty for the Chronic Impingement Syndrome
- Defined the chronic impingement syndrome and attributed rotator cuff wear to mechanical compression under the anterior acromion
- Described anterior acromioplasty - removal of the anterior acromial prominence and any spurs - to decompress the cuff
- Established the conceptual basis for the open subacromial decompression performed through a superior approach
- Reported reliable pain relief in carefully selected patients
Repair of Ruptures of the Rotator Cuff of the Shoulder, With a Note on the Advantages of the Trans-Acromial Route
- The classic description of the dorsal trans-acromial approach to the rotator cuff
- Advocated an acromial osteotomy to expose large or retracted cuff tears that are inaccessible by other routes
- Permitted direct repair of otherwise irreparable-looking tears
- Remains the historical reference for the extensile transacromial technique
Anatomy and Relationships of the Suprascapular Nerve: Anatomical Constraints to Mobilization of the Supraspinatus and Infraspinatus
- Detailed the course of the suprascapular nerve and its motor branches to the cuff muscles
- Demonstrated that the nerve tethers the supraspinatus and infraspinatus only a short distance from the glenoid
- Established that lateral mobilization of the cuff is limited by nerve tension, risking neurapraxia
- Provides the anatomical basis for protecting the nerve during cuff mobilization through any approach
Rotator Cuff Disease of the Shoulder
- A comprehensive review of the pathology, classification, and surgical treatment of rotator cuff disease
- Discussed tear size and tissue quality as determinants of reparability
- Reviewed open repair techniques and their expected outcomes
- A widely cited reference framing cuff disease for an era when open repair predominated
The Morphology of the Acromion and Its Relationship to Rotator Cuff Tears
- Classified acromial morphology into three types - flat (type I), curved (type II), and hooked (type III)
- Found the hooked type III acromion to be strongly associated with full-thickness rotator cuff tears
- Linked acromial architecture to mechanical impingement of the cuff
- Provided the rationale for acromioplasty as part of cuff surgery