Beach Chair | Axillary Nerve 5-7 cm Rule | Limited Split with Stay Sutures
Surgical Imaging
The axillary nerve exits the quadrilateral space and winds around the surgical neck of the humerus approximately 5-7 cm distal to the lateral border of the acromion. Any deltoid split must be limited to less than 5 cm from the acromion edge and the distal apex must be tagged with a stay suture to prevent distal propagation. Nerve injury causes deltoid paralysis and sensory loss over the lateral shoulder.
The deltoid is split in line with its fibres from the anterolateral acromion distally. Because the entire deltoid is innervated by the axillary nerve, there is no internervous plane. The split is therefore kept short and the distal end is closed with a non-absorbable stay suture that acts as a mechanical stop. This protects the nerve while allowing adequate exposure of the supraspinatus and rotator interval.
The coracoacromial ligament forms the anterior roof of the subacromial space. It must be divided close to the acromion to gain full access to the supraspinatus tendon and rotator interval. Division also allows anterior acromioplasty if required. The ligament is not repaired at closure.
At closure the deltoid must be securely reattached to the acromion using transosseous sutures or suture anchors. Failure of repair leads to deltoid detachment, abduction weakness, and a characteristic cosmetic deformity. The repair is the most important step for long-term shoulder function.
The beach chair position with the patient at 60-70 degrees allows gravity-assisted arm positioning, easy conversion to arthroscopy, and excellent fluoroscopic access. The head is secured, all pressure points padded, and the arm is draped free. The C-arm comes from the opposite side or from the head.
Ideal for mini-open rotator cuff repair, greater tuberosity ORIF, and subacromial decompression when arthroscopy is not available. The approach gives excellent access to the supraspinatus and rotator interval but cannot reach the infraspinatus or teres minor without extension or a separate posterior approach. Distal extension is limited by the axillary nerve.
At a Glance
The anterosuperior deltoid-split approach provides direct access to the supraspinatus tendon, rotator interval, and superior humeral head through a limited longitudinal split of the deltoid originating at the anterolateral acromion. It is the classic exposure for mini-open rotator cuff repair and greater tuberosity fixation. The critical safety principle is the axillary nerve location 5-7 cm distal to the acromion; the split must therefore be short (less than 5 cm) and the distal apex must be tagged with a stay suture to prevent propagation. There is no true internervous plane because the entire deltoid is supplied by the axillary nerve. The coracoacromial ligament is divided to open the subacromial space. Secure deltoid-to-acromion repair at closure is mandatory. The approach is performed in the beach chair position and is easily combined with arthroscopy.
DELTOIDDELTOID SPLIT - Surgical Steps
Hook:DELTOID split - always tag the distal apex and repair securely!
AXILLARYAXILLARY NERVE - Protection Rules
Hook:AXILLARY nerve - the 5-7 cm rule is non-negotiable!
DANGERSSHOULDER APPROACH - Danger Structures
Hook:DANGERS - nerve, detachment, and cuff are the big three!
Indications and Approach Selection
Primary Indications:
- Mini-open or open rotator cuff repair (supraspinatus and rotator interval tears)
- Greater tuberosity fracture fixation (displaced fragments)
- Subacromial decompression when arthroscopic equipment unavailable
- Biceps tenodesis or tenotomy in conjunction with cuff work
- Limited proximal humerus fracture exposure (greater tuberosity component)
- Revision of failed mini-open cuff repairs
Why This Approach is Chosen: The anterosuperior deltoid-split provides direct access to the supraspinatus insertion and the superior humeral head without violating the deltoid origin extensively. It allows excellent visualisation for tendon mobilisation, anchor placement, and greater tuberosity reduction while preserving the majority of the deltoid. The limited split keeps the axillary nerve safe when the 5-7 cm rule is respected.
Contraindications:
- Large or massive rotator cuff tears requiring extensive mobilisation (consider open or arthroscopic)
- Infraspinatus or teres minor pathology (needs posterior or combined approach)
- Severe glenohumeral arthritis requiring arthroplasty (different exposure)
- Active infection or poor skin quality over the acromion
- Patient unable to tolerate beach chair positioning (severe kyphosis, cervical instability)
Alternative Approaches:
- Arthroscopic approach: Preferred for most rotator cuff repairs and decompression
- Deltopectoral approach: For anterior shoulder, proximal humerus fractures, arthroplasty
- Posterior approach: For infraspinatus, teres minor, or posterior glenoid
- Extended lateral approach: When more distal humeral exposure is required
Overview
Anterosuperior Deltoid-Split Approach provides limited direct access to the supraspinatus tendon, rotator interval, and superior humeral head through a longitudinal split of the deltoid originating at the anterolateral acromion.
Key Characteristics:
- Beach chair or lateral decubitus positioning
- Axillary nerve protection by limited split (less than 5 cm) and stay suture
- No true internervous plane (deltoid split within single nerve territory)
- Coracoacromial ligament division required for exposure
- Secure deltoid reattachment mandatory at closure
Why This Approach Matters:
- Classic exposure for mini-open rotator cuff repair before arthroscopy became dominant
- Still used when arthroscopic equipment is unavailable or for teaching
- Provides excellent access to greater tuberosity for fracture fixation
- Allows easy conversion between arthroscopic and open phases
- High-yield surgical approach for Operative Surgery station
Exam Relevance:
- Axillary nerve distance (5-7 cm) is a classic viva question
- Deltoid repair technique and consequences of failure are frequently tested
Anatomy
Bony Landmarks: The acromion is the key proximal landmark. Its anterolateral corner is the starting point for the deltoid split. The coracoid process lies anterior and medial and is palpated to orient the incision. The deltoid tuberosity on the humerus marks the distal limit of safe exposure.
Muscular Layers:
|| Layer | Muscle | Nerve Supply | Action | ||-------|--------|--------------|--------| || Superficial | Deltoid (anterior and middle) | Axillary nerve | Abduction, flexion, extension | || Deep | Supraspinatus | Suprascapular nerve | Initiation of abduction, external rotation | || Deep | Subscapularis (rotator interval) | Upper and lower subscapular nerves | Internal rotation | || Deep | Biceps long head | Musculocutaneous | Humeral head depression |
Neurovascular Anatomy:
|| Structure | Location | Clinical Significance | ||-----------|----------|----------------------| || Axillary nerve | Winds around surgical neck 5-7 cm distal to acromion | MOST IMPORTANT - injury causes deltoid paralysis and lateral shoulder numbness | || Musculocutaneous nerve | Enters coracobrachialis 3-5 cm distal to coracoid tip | At risk if dissection carried too far medially | || Cephalic vein | Runs in deltopectoral groove | May be encountered if incision drifts anteriorly | || Suprascapular nerve | Enters suprascapular notch | Not directly at risk but retraction injury possible | || Subacromial bursa | Lies beneath acromion and deltoid | Must be excised for visualisation |
Rotator Cuff Anatomy Relevant to Approach: The supraspinatus inserts on the superior facet of the greater tuberosity. The rotator interval lies between supraspinatus and subscapularis and contains the long head of biceps. The coracoacromial ligament forms the anterior roof and must be divided to access these structures fully.
Internervous Plane
Deep Internervous Plane: There is no true internervous plane in the anterosuperior deltoid-split approach. The deltoid is split in line with its fibres within the territory of a single nerve (axillary nerve). The approach therefore relies on a limited muscle-splitting interval rather than an inter-nervous plane.
Superficial Dissection: The skin and subcutaneous tissue are divided directly onto the deltoid fascia. The deltoid is split longitudinally in line with its fibres starting at the anterolateral acromion. Because the entire deltoid is supplied by the axillary nerve, any split risks denervation distal to the split if the nerve is injured.
The absence of a true internervous plane is the defining feature of this approach. All deltoid fibres are innervated by the axillary nerve after it exits the quadrilateral space. The safety strategy is therefore entirely mechanical: limit the split length to less than 5 cm from the acromion, tag the distal apex with a non-absorbable stay suture, and avoid vigorous or prolonged retraction. This prevents both direct nerve injury and propagation of the split that would stretch the nerve.
Structures at Risk in Each Layer:
|| Layer | Structure | Protection Strategy | ||-------|-----------|-------------------| || Superficial | Axillary nerve (terminal branches) | Limit split to less than 5 cm, tag apex, gentle retraction | || Deep | Musculocutaneous nerve | Avoid medial dissection beyond coracoid base | || Deep | Cephalic vein | Identify and retract laterally if encountered | || Articular | Rotator cuff tendons | Handle gently, protect with retractors during drilling | || Articular | Long head of biceps | Identify and protect or tenodese if indicated |
Positioning and Patient Setup
Position: Beach Chair on Radiolucent Table
Pre-positioning Checklist:
- Confirm cervical spine stability and no contraindication to beach chair
- All pressure points padded (occiput, scapulae, sacrum, heels)
- Head secured in neutral position with Mayfield or similar holder
- Arm draped free with full range of motion available
- C-arm positioned from opposite side or head of table
- Arthroscopy tower available if hybrid procedure planned
Positioning Details:
- Patient at 60-70 degrees upright in beach chair
- Affected arm at side or supported on a padded arm board
- Table tilted 10-15 degrees reverse Trendelenburg
- Blood pressure cuff on non-operative arm
- Tourniquet not usually required for shoulder approaches
Beach chair positioning carries risks of cerebral hypoperfusion if the head is elevated above heart level, brachial plexus injury from arm positioning, and pressure sores. Maintain systolic blood pressure above 90 mmHg or mean arterial pressure within 20% of baseline. Document all protective measures.
Surgical Technique
Patient Position: Beach chair at 60-70 degrees with head secured. Affected arm draped free. Surgeon stands on the operative side with the assistant opposite. The C-arm or arthroscopy tower is positioned for easy access.
Surface Landmarks:
- Acromion (entire outline palpated, anterolateral corner marked)
- Coracoid process (anterior and medial)
- Deltoid tuberosity (distal limit of safe exposure)
- Clavicle (if proximal extension planned)
Skin Incision: A 4-6 cm longitudinal incision is made starting at the anterolateral corner of the acromion and extending distally in line with the deltoid fibres. The incision can be curved slightly anteriorly if more anterior access is required.
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 55-year-old manual worker presents with a full-thickness supraspinatus tear confirmed on MRI. Arthroscopy is not available. How would you perform an anterosuperior deltoid-split approach for repair?”
“During a deltoid-split approach, the distal split begins to propagate under retraction. What is your immediate response and how do you protect the axillary nerve?”
“A 42-year-old falls onto the shoulder and sustains a displaced greater tuberosity fracture. CT confirms 1 cm superior displacement. How would you approach fixation through the anterosuperior deltoid-split?”
Evidence Base
A less invasive surgery for rotator cuff tear: mini-open repair
The rotator cuff. Full-thickness tears. Mini-open repair
The posterior branch of the axillary nerve: an anatomic study
Neurologic complications of shoulder surgery
MCQ Practice Points
Q: At what distance from the acromion does the axillary nerve cross the humerus? A: The axillary nerve lies 5-7 cm distal to the lateral border of the acromion in the majority of individuals. This distance is the single most important safety landmark for the anterosuperior deltoid-split approach.
Q: What is the maximum safe length of the deltoid split from the acromion? A: The split should be limited to less than 5 cm from the acromion edge. A heavy non-absorbable stay suture must be placed at the distal apex to prevent further propagation.
Q: Is there an internervous plane in the anterosuperior deltoid-split approach? A: No. The entire deltoid is innervated by the axillary nerve. The approach is a limited muscle-splitting interval within a single nerve territory. Safety depends on mechanical protection (length limit and stay suture).
Q: What are the consequences of inadequate deltoid repair? A: Deltoid detachment produces abduction weakness, a characteristic cosmetic deformity (deltoid drop), and often requires complex revision reconstruction. Secure transosseous or anchor repair at closure is mandatory.
Q: Why is the coracoacromial ligament divided during this approach? A: Division of the coracoacromial ligament opens the anterior subacromial space, allows full visualisation of the supraspinatus and rotator interval, and permits anterior acromioplasty when indicated. The ligament is not repaired.