import { ComparisonTable, ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MedicalImage, MnemonicCard, OnePagerSummary, SafetyAlert, Tab, Tabs, Timeline, TimelineItem, VivaScenario, VivaScenarioSection } from '@/components/mdx' {/* SECTION 1: ONE-PAGER SUMMARY */} {/* SECTION 2: EXAM WARNING */} This is a **true internervous plane** between infraspinatus (suprascapular nerve) and teres minor (axillary nerve). This anatomic separation provides safe access without denervating muscles, but both nerves remain at risk with deep dissection. The **axillary nerve** is the primary structure at risk. It runs along the inferior border of teres minor and subscapularis, approximately **5-7cm below the posterolateral acromion**. Deltoid split must not exceed this distance. The posterior approach is **less commonly used** than anterior approaches. Primary indications are posterior instability requiring open repair, posterior glenoid fractures, and locked posterior dislocations. Most posterior labral work is now arthroscopic. **Lateral decubitus** is most common position, with arm supported in slight flexion and internal rotation. Prone position is alternative. Both allow gravity to assist with exposure and maintain arm position during surgery. {/* SECTION 2.5: QUICK DECISION GUIDE */} {/* SECTION 3: MNEMONICS */} {/* SECTION 4: OVERVIEW */} **The posterior approach to the shoulder** provides direct access to the posterior glenoid, posterior humeral head, and posterior soft tissue structures. It is less commonly used than anterior approaches but remains essential for specific indications. **Primary indications:** - **Posterior instability** requiring open stabilization (revision cases, bone loss) - **Posterior glenoid fractures** and bone grafting procedures - **Locked posterior shoulder dislocation** with associated humeral head impaction - **Posterior capsular procedures** including capsular shift - **Selected humeral head fractures** with posterior comminution The posterior approach was more commonly used historically for posterior labral repairs and instability. With advances in **arthroscopic techniques**, most posterior labral pathology is now treated arthroscopically. Open posterior approach is now reserved for revision cases, bone loss requiring grafting, and specific fracture patterns. **Advantages of posterior approach:** - True internervous plane (infraspinatus vs teres minor) - Direct visualization of posterior glenoid - Minimal vascular structures at risk - Good access to posterior humeral head **Disadvantages:** - Limited exposure of rotator cuff - Risk to axillary nerve with deltoid split - Positioning requirements (lateral decubitus or prone) - Infraspinatus detachment may be required for extensive exposure {/* SECTION 5: ANATOMY */} **Surface anatomy and landmarks:** The key surface landmarks guide incision placement and approach development: - **Acromion** - posterior edge marks superior extent - **Spine of scapula** - runs medially from acromion - **Posterior axillary fold** - marks inferior extent of incision - **Posterolateral corner of acromion** - key reference point for axillary nerve distance **Muscular layers:** **Neurovascular structures at risk:** The **axillary nerve** and **posterior circumflex humeral vessels** exit the quadrangular space and course along the inferior border of subscapularis anteriorly and teres minor posteriorly. The nerve is located approximately **5-7cm inferior to the posterolateral corner of the acromion**. This defines the safe limit for deltoid splitting. **Quadrangular space boundaries:** - Superior: Teres minor - Inferior: Teres major - Medial: Long head of triceps - Lateral: Surgical neck of humerus The axillary nerve and posterior circumflex humeral vessels traverse this space. Deep dissection along the inferior aspect of the approach risks injury to these structures. **Posterior capsule:** The posterior capsule is the deepest layer encountered. It is relatively thin compared to the anterior capsule. Opening the capsule longitudinally provides access to: - Posterior glenoid and labrum - Posterior humeral head - Glenohumeral joint {/* SECTION 6: INTERNERVOUS PLANE */} The posterior approach to the shoulder utilizes a **true internervous plane**, which is the key anatomic basis for this approach. **Definition of the plane:** The internervous plane exists between: - **Infraspinatus muscle** (superior) - supplied by suprascapular nerve (C5, C6) - **Teres minor muscle** (inferior) - supplied by axillary nerve branch (C5, C6) This is a **true internervous plane** because the two muscles forming the interval are supplied by different nerves. Working between these muscles does not denervate either muscle, making this a safe anatomic approach. However, both nerves remain at risk from deep dissection or excessive retraction. **Characteristics of the plane:** **Avascular nature:** - The interval between infraspinatus and teres minor is relatively avascular - Natural separation exists between the muscles - Easily developed with blunt dissection - Minimal bleeding during plane development **Development technique:** - Identify both muscles by their insertions on greater tuberosity - **Infraspinatus** inserts on superior and middle facets - **Teres minor** inserts on inferior facet - Use finger or blunt instrument to separate muscles - Work from lateral (humeral side) to medial (scapular side) - Plane widens as dissection proceeds medially **Nerve anatomy related to plane:** **Suprascapular nerve:** - Passes through suprascapular notch (beneath superior transverse scapular ligament) - Travels around lateral scapular spine in spinoglenoid notch - Supplies infraspinatus muscle - **At risk**: Deep medial dissection around glenoid neck - **Protection**: Stay within internervous plane, avoid excessive medial retraction **Axillary nerve:** - Exits quadrangular space with posterior circumflex humeral vessels - Courses along inferior border of teres minor - Branches to supply teres minor and deltoid - Located 5-7cm below posterolateral acromion - **At risk**: Excessive deltoid split, inferior retraction - **Protection**: Limit deltoid split to 5cm, gentle retraction **Functional significance:** Working in the internervous plane provides several advantages: - **No muscle denervation** - both muscles maintain their nerve supply - **Safe access** to posterior structures - **Minimizes bleeding** due to avascular nature - **Easily developed** without need for extensive dissection - **Can be closed** without functional deficit The internervous plane is the fundamental anatomic principle that makes the posterior approach safe and effective. {/* SECTION 7: PATIENT POSITIONING */} Proper patient positioning is critical for successful posterior shoulder surgery. Two main positions are used: lateral decubitus and prone. **Lateral decubitus position (most common):** This is the preferred position for most posterior shoulder procedures. **Setup steps:** 1. **Patient on opposite side** (for right shoulder surgery, left lateral decubitus) 2. **Positioning device** - bean bag or vacuum positioning device 3. **Axillary roll** - placed under dependent axilla to protect brachial plexus 4. **Pressure points padded** - dependent heel, elbow, lateral knee, fibular head 5. **Table break** - position patient so shoulder is at table break for flexibility 6. **Affected shoulder at table edge** - allows arm to hang and be manipulated **Arm support options:** - **Mechanical arm holder** - attaches to table, supports arm in desired position - **Padded Mayo stand** - arm rests on sterile padded stand - **Assistant holding** - less ideal but workable for short cases **Arm position:** - **Slight flexion** (20-30 degrees) - **Slight internal rotation** - Must allow **full range of motion** for intraoperative assessment - Gravity assists with posterior exposure **Advantages of lateral decubitus:** - Gravity-assisted exposure of posterior structures - Easy arm manipulation and positioning - Familiar to most shoulder surgeons - Good visualization of posterior anatomy - Can assess stability through range of motion **Disadvantages:** - Patient must be securely fixed to prevent rolling - Requires careful attention to pressure points - Can be unstable in obese patients - Difficult to convert to anterior approach if needed In lateral decubitus position, the patient must be **securely stabilized** to prevent rolling. Use a bean bag or vacuum positioning device, and ensure the table is locked. An unstable patient position is dangerous and compromises surgical exposure. **Prone position (alternative):** Less commonly used but valid for specific indications. **Setup steps:** 1. **Patient prone** on operating table 2. **Head turned** away from operative side 3. **Chest rolls** to allow chest expansion for ventilation 4. **Arm support** - hanging off table edge or on radiolucent arm board 5. **Padding** - forehead, chest, anterior iliac crests, knees **Arm position options:** - **Hanging freely** off edge of table - **Supported on arm board** in abduction **Advantages:** - Very stable patient position (cannot roll) - Both shoulders accessible if needed for comparison - Good for scapular fractures requiring extensive posterior access **Disadvantages:** - Difficult arm manipulation and ROM testing - Airway management concerns (difficult access to airway) - Less familiar to many shoulder surgeons - Cannot easily convert to anterior approach - Arm hanging position can cause traction injury if prolonged **Beach chair position (not recommended):** Beach chair is commonly used for anterior and superior shoulder procedures but is **not ideal for posterior approaches**: - Posterior exposure limited by patient leaning back - Gravity works against exposure - Arm positioning difficult for posterior access - Only consider if combined anterior-posterior pathology **Positioning checklist before incision:** Before making incision, confirm: - [ ] Patient position secure (cannot shift or roll) - [ ] All pressure points padded - [ ] Axillary roll in place (lateral decubitus) - [ ] Arm support allows full ROM - [ ] C-arm can access shoulder if needed - [ ] All team members can reach surgical field - [ ] Patient identification and surgical site verified - [ ] Antibiotics administered Proper positioning sets the foundation for safe and efficient surgery. {/* SECTION 8: SURGICAL TECHNIQUE */} ### Posterior Approach Variants ### Classification of Indications | Indication Category | Examples | Approach Preference | |---------------------|----------|---------------------| | Posterior Instability | Labral tear, bone loss | Standard posterior | | Glenoid Fractures | Posterior column, rim | Standard or extensile | | Locked Dislocations | Posterior with reverse Hill-Sachs | Standard posterior | | Scapular Fractures | Body, spine, glenoid | Extensile posterior | ### Related Classifications **Posterior Glenoid Bone Loss Classification:** - Less than 15%: Soft tissue repair (arthroscopic) - 15-25%: Consider bone block (posterior approach) - Greater than 25%: Bone block required (posterior approach) **Reverse Hill-Sachs Lesion Classification:** - Less than 20%: Observation or small graft - 20-40%: McLaughlin procedure (subscapularis transfer) - 40-50%: Allograft reconstruction - Greater than 50%: Consider arthroplasty The posterior approach is selected when pathology is primarily **posterior** and **open access is required**. Most posterior labral tears are now treated arthroscopically. Open posterior approach is reserved for **bone loss requiring grafting, revision instability, locked dislocations, and posterior glenoid fractures**. ### Preoperative Assessment for Posterior Approach **History:** - Mechanism of injury (posterior instability pattern, seizure, electrocution) - Previous surgery (arthroscopic portals, scars) - Functional demands and goals - Pain location and character **Physical Examination:** - **Inspection**: Posterior fullness (locked dislocation), muscle wasting - **Range of motion**: Internal rotation limitation, forward flexion - **Stability testing**: Jerk test, posterior load-and-shift, Kim test - **Neurovascular**: Axillary nerve function (deltoid, sensation) ### Key Findings Favoring Posterior Approach | Finding | Significance | Approach Decision | |---------|--------------|-------------------| | Positive jerk test | Posterior labral tear | Arthroscopic vs open (bone loss dependent) | | Fixed posterior dislocation | Locked posterior dislocation | Posterior approach likely | | Posterior glenoid tenderness | Posterior glenoid pathology | Posterior approach for bone work | | Previous failed arthroscopy | Revision required | Open posterior approach | ### Neurological Assessment **Axillary Nerve Function:** - Test deltoid strength (abduction against resistance) - Sensation over lateral shoulder (badge area) - Document preoperatively as baseline - Critical for comparison postoperatively **Suprascapular Nerve Function:** - External rotation strength (infraspinatus) - Scapular muscle bulk assessment - May be affected by spinoglenoid cyst **Document axillary and suprascapular nerve function preoperatively.** Both nerves are at risk during posterior approach. A pre-existing deficit changes surgical planning and postoperative expectations. If deficit is present, consider EMG/NCS before surgery. ### Soft Tissue Assessment - Previous scars and portal sites - Muscle atrophy (infraspinatus, teres minor) - Skin quality and vascularity - Body habitus (affects access) ### Imaging for Posterior Approach Planning **Plain Radiographs:** - **AP views**: Assess joint congruency, humeral head position - **Axillary view**: Critical - shows posterior head position (locked dislocation) - **Y-view (scapular lateral)**: Confirms head-glenoid relationship **CT Scan:** - Essential for bone pathology (glenoid fractures, bone loss) - 3D reconstructions for surgical planning - Measure posterior bone loss percentage - Assess reverse Hill-Sachs lesion size **MRI:** - Posterior labral tears (POLPSA, Kim lesion) - Rotator cuff integrity - Posterior capsular redundancy - Associated pathology ### Key Imaging Findings | Finding | Imaging | Implication | |---------|---------|-------------| | Posterior glenoid bone loss greater than 20% | CT 3D reconstruction | Bone block required | | Reverse Hill-Sachs greater than 25% | CT axial | Subscapularis transfer or graft | | Posterior labral tear | MRA or MRI | Repair (arthroscopic or open) | | Posterior glenoid fracture | CT | ORIF via posterior approach | ### Quantifying Bone Loss **Posterior Glenoid Bone Loss:** - Measured on axial CT at mid-glenoid level - Compare to normal glenoid circle - Greater than 20% suggests need for bone grafting - En-face 3D CT reconstructions helpful **Reverse Hill-Sachs Lesion Sizing:** - Percentage of humeral head involved - Measured on axial CT - Guides treatment: less than 20% observe, 20-40% McLaughlin, greater than 40% allograft The **axillary view radiograph** is the most important plain film for posterior dislocation. Many locked posterior dislocations are missed because only AP views are obtained. The axillary view clearly shows the humeral head position relative to the glenoid. ### Advanced Imaging **CT with 3D Reconstructions:** - Best for glenoid bone loss quantification - Guides graft sizing - Surgical templating **MR Arthrography:** - Superior for labral pathology - Identifies capsular tears and redundancy - POLPSA lesion (posterior labral periosteal sleeve avulsion) ### Approach Selection Algorithm ### Indications for Open Posterior Approach **Absolute:** - Posterior glenoid fracture requiring ORIF - Significant posterior bone loss (greater than 20%) requiring graft - Failed arthroscopic posterior stabilization with bone loss **Relative:** - Locked posterior dislocation - Revision posterior instability (even without bone loss) - Large reverse Hill-Sachs requiring bone graft ### Combined Approach Considerations **When to Consider Combined Anterior + Posterior:** - Locked posterior dislocation with subscapularis transfer (McLaughlin) requiring anterior access for transfer and posterior access for reduction - Bipolar instability (multidirectional with significant posterior component) - Complex glenoid fractures with anterior and posterior components **Staging Options:** - Single-stage: Anterior approach first, then posterior - Two-stage: Staged procedures 4-6 weeks apart - Choice depends on pathology complexity and patient factors The **McLaughlin procedure** (subscapularis transfer into reverse Hill-Sachs lesion) can be performed through either approach. Posterior approach provides direct visualization of the humeral head defect. Some surgeons prefer anterior (deltopectoral) approach for subscapularis mobilization. Combined approach may be needed for large defects. ### Non-Operative Management **When Appropriate:** - Small posterior labral tears without instability - Minimal bone loss (less than 10%) - First-time posterior subluxation in non-athlete - Elderly, low-demand patients **Protocol:** - Physical therapy for dynamic stabilizers - Activity modification - Re-assess if symptoms persist **Identification of surface landmarks** Before incision, palpate and mark: 1. **Posterior border of acromion** - superior reference 2. **Spine of scapula** - medial landmark 3. **Posterolateral corner of acromion** - key reference for axillary nerve 4. **Posterior axillary fold** - inferior extent **Mark the safe zone for deltoid split:** - Measure 5cm inferior to posterolateral corner of acromion - Mark this point - deltoid split should not extend beyond this **Plan the incision:** - Oblique incision from posterior acromion extending toward posterior axillary fold - Length typically 8-12cm depending on patient size and pathology - Incision runs parallel to muscle fibers of posterior deltoid The incision should be placed just medial to the posterior edge of the acromion and extend obliquely toward the posterior axillary fold. This provides access to the interval between infraspinatus and teres minor while avoiding injury to cutaneous nerves. This concludes landmark identification. **Skin incision and subcutaneous dissection** **Incision:** - Make skin incision as planned (8-12cm oblique) - Deepen through subcutaneous tissue - Identify and preserve cutaneous nerves when possible **Exposure of deltoid:** - Identify posterior deltoid muscle fibers - Note fiber direction (runs from acromion obliquely to lateral humerus) - Develop plane between subcutaneous tissue and deltoid fascia **Deltoid split:** - Split deltoid **in line with its fibers** (parallel to muscle fiber direction) - Start at posterior acromion - Extend split **no more than 5cm inferior** to posterolateral corner of acromion - Use blunt dissection to spread fibers The deltoid split must **NOT exceed 5cm below the posterolateral corner of the acromion**. Beyond this distance, the axillary nerve is at high risk of injury. The nerve courses along the deep surface of deltoid approximately 5-7cm below the acromion. Injury results in deltoid denervation and significant functional deficit. **Retraction:** - Place retractors to spread deltoid split - Avoid aggressive retraction inferiorly (risk to axillary nerve) - Use self-retaining retractors if available Deltoid splitting is now complete. **Development of internervous plane** Deep to the deltoid, identify the rotator cuff muscles: **Identification:** - **Infraspinatus** (superior) - larger muscle, fan-shaped - **Teres minor** (inferior) - smaller, more cylindrical - Natural interval between these muscles - the internervous plane **Develop the interval:** - Use blunt dissection to separate infraspinatus from teres minor - The plane is relatively avascular - Separate muscles with finger or blunt instrument - Work from lateral (humeral insertion) to medial (scapula) **Extend the interval:** - Continue dissection medially toward posterior glenoid - The interval widens as you proceed medially - Identify posterior capsule deep to both muscles To confirm you are in the correct plane, note that: - **Infraspinatus** inserts on superior and middle facets of greater tuberosity - **Teres minor** inserts on inferior facet of greater tuberosity - The interval between them is relatively bloodless - Both muscles can be retracted without denervation (different nerve supply) **Nerve awareness:** - **Suprascapular nerve** is superior, supplying infraspinatus - **Axillary nerve** is inferior, supplying teres minor - Both nerves are protected by working in the internervous plane - Avoid excessive retraction that can stretch either nerve The internervous plane is now developed. **Exposure of posterior capsule and glenoid** **For limited exposure (labral repair, capsular work):** - Retract infraspinatus superiorly - Retract teres minor inferiorly - Identify posterior capsule - Open capsule longitudinally to access joint **For extensive exposure (fractures, bone grafting):** May require **infraspinatus detachment**: 1. **Identify infraspinatus insertion** on greater tuberosity (superior and middle facets) 2. **Detach infraspinatus** sharply with cuff of tissue for later repair 3. **Tag sutures** in infraspinatus for later identification 4. **Reflect infraspinatus medially** to expose posterior capsule and glenoid **Capsulotomy:** - Make **longitudinal capsular incision** - Extend from superior to inferior - Stay capsular - avoid injury to labrum unless planned - Use retractors to maintain exposure **Visualization achieved:** - Posterior glenoid - Posterior labrum - Posterior humeral head - Glenohumeral joint If infraspinatus is detached, ensure you maintain tissue quality for later repair. Take a cuff of bone or leave tissue tag for secure reattachment. Failure to repair infraspinatus leads to external rotation weakness and poor outcomes. Deep exposure is now complete. **Pathology-specific techniques** Once exposure is achieved, proceed with planned procedure: **Posterior labral repair:** - Debride labral tear - Prepare glenoid bone edge - Place suture anchors in posterior glenoid - Repair labrum and capsule to glenoid - Consider capsular plication if redundant **Posterior glenoid fracture fixation:** - Reduce fracture fragments - Assess articular congruity - Place plate on posterior glenoid neck - Lag screws for large fragments - Assess stability **Locked posterior dislocation:** - Reduce dislocation (may require subscapularis release from anterior) - Assess reverse Hill-Sachs lesion size - Small lesion (less than 20%): observe - Moderate lesion (20-40%): McLaughlin procedure (subscapularis transfer) - Large lesion (greater than 40%): consider allograft **Posterior bone block (glenoid bone loss):** - Prepare posterior glenoid surface - Size and shape bone graft (iliac crest or allograft) - Position graft to restore glenoid arc - Fix with screws Each pathology has specific technical requirements beyond scope of approach description. **Layered closure** **Capsule:** - Close posterior capsule with absorbable suture - Anatomic repair to restore normal tension **Infraspinatus (if detached):** - Reattach infraspinatus to greater tuberosity - Use bone tunnels or suture anchors - Ensure anatomic restoration - Test repair strength **Rotator interval:** - If infraspinatus was left attached, no muscle repair needed - Simply approximate interval with absorbable suture **Deltoid:** - Repair deltoid split with absorbable suture - Side-to-side repair of fascia - Ensure secure closure to prevent postoperative weakness **Subcutaneous and skin:** - Close subcutaneous layer with absorbable suture - Skin closure with subcuticular or interrupted sutures - Sterile dressing and sling application The most critical aspect of closure is **secure infraspinatus repair** if it was detached. External rotation strength depends on infraspinatus function. Inadequate repair leads to significant functional deficit. Deltoid repair is also important to prevent posterior deltoid weakness. Surgical closure is now complete. {/* SECTION 9: COMPLICATIONS */} **Axillary nerve injury:** The axillary nerve is the most important structure at risk. **Mechanism:** - Direct injury from deltoid split extending too far inferiorly - Stretch injury from excessive retraction - Thermal injury from cautery near nerve **Prevention:** - Limit deltoid split to **5cm below posterolateral acromion** - Avoid aggressive inferior retraction - Identify nerve if exposure extends inferiorly - Use bipolar cautery carefully **Diagnosis:** - Inability to abduct shoulder (deltoid paralysis) - Sensory loss over lateral shoulder (badge area) - EMG/NCS confirmation **Management:** - If identified intraoperatively, explore and assess - If neuropraxia expected, observe for 3-6 months - If no recovery by 6 months, consider nerve exploration or tendon transfers The **axillary nerve** exits the quadrangular space and travels along the deep surface of the deltoid muscle. It courses approximately **5-7cm inferior to the posterolateral corner of the acromion**. Deltoid splits extending beyond this distance place the nerve at direct risk of injury. **Infraspinatus dysfunction:** If infraspinatus is detached and not properly repaired: - **External rotation weakness** - Difficulty with arm positioning - Compensatory anterior deltoid overuse Prevention requires secure anatomic repair with bone tunnels or anchors. **Stiffness:** Posterior capsular scarring can lead to loss of internal rotation and forward flexion. **Prevention:** - Avoid excessive capsular tightening - Early passive motion (within 1-2 weeks) - Protect repair while allowing motion {/* SECTION 10: POSTOPERATIVE CARE */} **Immediate postoperative (Week 0-2):** - Sling immobilization - Ice and elevation - Pain control - Pendulum exercises only - No active motion if infraspinatus detached - Continue sling between exercises - Begin passive range of motion - Avoid terminal ranges - Protect repair - Physiotherapy assessment **Rehabilitation phases:** **Weeks 0-6: Protection phase** **Goals:** - Protect surgical repair - Prevent stiffness - Maintain passive motion **Restrictions:** - Sling immobilization (continuous for first 2 weeks, then with exercises) - **No active external rotation** if infraspinatus detached (until 6 weeks) - No resisted movements - Avoid end-range positions **Allowed activities:** - Passive range of motion (all planes) - Pendulum exercises - Elbow, wrist, hand motion - Gentle active-assisted motion after week 2-3 **Specific considerations:** - If **infraspinatus detached**: No active external rotation until week 6 - If **labral repair**: No combined abduction/external rotation until week 6 - If **fracture fixation**: Timeline depends on fixation stability Protection phase emphasizes healing while preventing stiffness. **Weeks 6-12: Active motion phase** **Goals:** - Restore full passive motion - Begin active motion - Initiate gentle strengthening **Progression:** - Active range of motion all planes - Active external rotation (if infraspinatus repaired and healed) - Progressive stretching to terminal ranges - Scapular strengthening - Begin rotator cuff isometrics **Restrictions:** - No resisted external rotation until week 8-10 - Avoid heavy lifting - No sports or high-demand activities **Expected outcomes:** - Full passive range of motion - Active motion approaching normal - Minimal pain with daily activities Active motion is the focus during this phase. **Weeks 12-24: Strengthening phase** **Goals:** - Restore full active motion - Progressive strengthening - Return to activities **Program:** - Rotator cuff strengthening (all four muscles) - Deltoid strengthening - Scapular stabilizer strengthening - Functional movement patterns - Sport-specific training if appropriate **Return to activity:** - Light activities: 3-4 months - Full activities: 4-6 months - Contact sports: 6-12 months (depends on repair) **Outcome assessment:** - Range of motion comparison - Strength testing - Functional scores - Patient satisfaction Full recovery may take 6-12 months depending on pathology and repair. Rehabilitation timelines must be modified based on: - **Procedure performed** (labral repair vs fracture fixation) - **Tissue quality** (revision vs primary) - **Fixation stability** (secure vs tenuous) - **Patient factors** (age, compliance, goals) Individualize the protocol to each patient and procedure. {/* SECTION 11: SPECIAL CONSIDERATIONS */} **Extensile approaches:** The posterior approach can be extended for greater exposure: **Superior extension:** - Continue incision along scapular spine - Access to supraspinatus and superior structures - Useful for scapular fractures **Inferior extension:** - Extend toward posterior axillary fold - Requires identification and protection of axillary nerve - Provides access to inferior glenoid and humeral shaft **Combined approaches:** Some pathology requires combined anterior and posterior approaches: - **Complex glenoid fractures** with anterior and posterior columns involved - **Revision arthroplasty** with component removal needs - **Locked dislocations** requiring subscapularis transfer and posterior access May stage approaches (anterior first, then posterior) or perform simultaneously. **Arthroscopic-assisted techniques:** Modern trend combines arthroscopy with mini-open posterior approach: - Arthroscopic assessment and labral work - Mini-open posterior for bone grafting or capsular shift - Smaller incision, less soft tissue disruption - Better visualization of intra-articular pathology The posterior approach has evolved with arthroscopic advances. Most **posterior labral work** that was historically done open is now performed arthroscopically. Open posterior approach is increasingly reserved for **bone loss, revision cases, and fracture management** where arthroscopy is inadequate. {/* SECTION 12: EVIDENCE BASE */} ### Outcomes by Procedure Type **Posterior Instability Surgery:** - **Arthroscopic repair**: 85-90% success for primary cases - **Open repair**: 80-90% success - **Open with bone block**: 85-95% success for bone loss cases **Locked Posterior Dislocation:** - Good results with early intervention (less than 6 weeks) - Reverse Hill-Sachs less than 25%: Excellent outcomes - Larger defects: Outcomes depend on reconstruction type ### Factors Affecting Outcomes **Positive Prognostic Factors:** - Primary surgery (not revision) - Minimal bone loss (less than 15%) - Early intervention (within 3 months of initial injury) - Compliant patient with rehabilitation - No associated lesions (cuff tears, arthritis) **Negative Prognostic Factors:** - Revision surgery (10-20% higher failure rate) - Significant bone loss (requires grafting) - Delayed treatment (chronic dislocations) - Voluntary posterior subluxation - Connective tissue disorders ### Complication Rates **Approach-Related:** - Axillary nerve injury: 1-5% - Infraspinatus weakness: 5-15% if detached - Deltoid weakness: 5-10% **Procedure-Related:** - Recurrent instability: 5-15% - Stiffness: 10-20% - Infection: less than 2% - Post-traumatic arthritis: 10-20% (fractures) Revision posterior instability surgery has **10-20% higher failure rates** than primary surgery. Key factors: bone loss (requires grafting), tissue quality (scarred), and patient selection (voluntary subluxators do poorly). Counsel patients appropriately about reduced success rates. {/* SECTION 13: VIVA SCENARIOS */} Thank you. This patient requires **ORIF of a displaced posterior glenoid fracture** and the **posterior approach** provides the best access for this pathology. **Patient Positioning:** I would position the patient in **lateral decubitus** on the opposite side, with the affected shoulder at the edge of the table. The arm would be supported in slight flexion and internal rotation using an arm holder or padded Mayo stand. This provides excellent posterior access and allows arm manipulation. **Surgical Approach - Key Steps:** **Landmarks:** I would palpate and mark the posterior acromion, spine of scapula, and posterior axillary fold. Importantly, I would identify the posterolateral corner of the acromion and measure **5cm inferiorly** - this marks the safe zone for deltoid splitting to avoid axillary nerve injury. **Incision:** An oblique incision from the posterior acromion toward the posterior axillary fold, typically 10-12cm long. **Deltoid:** Split the deltoid **in line with its fibers**, extending **no more than 5cm below the posterolateral acromion** to protect the axillary nerve which runs approximately 5-7cm from this landmark. **Internervous Plane:** This is a **true internervous plane** between infraspinatus (suprascapular nerve) and teres minor (axillary nerve). I would develop this plane with blunt dissection, working from lateral to medial. **Deep Exposure:** For fracture fixation, I would likely need to **detach the infraspinatus** from the greater tuberosity to gain adequate exposure of the posterior glenoid. I would tag this with sutures for secure repair at closure. **Capsule:** Open the posterior capsule longitudinally to visualize the fracture and glenoid articular surface. **Fracture Management:** Reduce the fracture, assess articular congruity, and fix with plate and screws on the posterior glenoid neck. **Closure:** Repair infraspinatus to greater tuberosity with strong fixation (bone tunnels or anchors), repair deltoid split, and close in layers. The critical safety points are the **5cm deltoid split limit** and ensuring **secure infraspinatus repair** to prevent external rotation weakness. } keyPoints={[ "Position: lateral decubitus on opposite side", "Landmarks: posterior acromion, posterolateral corner (measure 5cm for nerve)", "Incision: oblique from posterior acromion to posterior axillary fold", "Deltoid split: in line with fibers, maximum 5cm below posterolateral acromion", "Internervous plane: infraspinatus (suprascapular) and teres minor (axillary)", "Axillary nerve is at 5-7cm below posterolateral acromion - must protect", "Infraspinatus detachment often needed for fracture exposure", "Tag infraspinatus with sutures for secure repair", "Open posterior capsule longitudinally", "Closure: secure infraspinatus repair is critical" ]} traps={[ "Extending deltoid split beyond 5cm (axillary nerve injury)", "Not identifying/protecting axillary nerve", "Inadequate infraspinatus repair at closure", "Wrong positioning (beach chair poor for posterior access)", "Confusing the internervous plane" ]} followUp={["What is the internervous plane for the posterior approach?", "How far below the acromion is the axillary nerve?"]} /> Thank you. This is a **revision posterior instability case** with significant **posterior glenoid bone loss** - this requires **open posterior stabilization** with bone grafting. **Decision-Making:** The failed arthroscopic repair combined with 25% posterior glenoid bone loss mandates an open approach. I cannot adequately address the bone loss arthroscopically. The **posterior approach** is ideal for this revision scenario. **Surgical Plan:** 1. Open posterior approach to posterior glenoid 2. Bone graft (iliac crest autograft or structural allograft) to restore glenoid arc 3. Revision posterior labral repair 4. Posterior capsular shift for redundancy **Approach Modifications for Revision:** This is a **revision case** which changes several aspects: - **Expect scarring** from previous arthroscopy (posterior portal sites) - **Dissection will be more difficult** - careful tissue handling - **Nerve identification may be necessary** if extensive exposure needed - **Tissue quality may be poor** - plan for augmentation **Specific Technique for Bone Loss:** After developing the internervous plane and exposing the posterior glenoid through capsulotomy: 1. **Assess bone loss** - confirm 25% deficiency on posterior glenoid 2. **Prepare glenoid surface** - debride to bleeding bone 3. **Size bone graft** (iliac crest or allograft) to restore glenoid arc 4. **Position graft** flush with articular surface posteriorly 5. **Fix with 2-3 screws** parallel to glenoid face 6. **Repair labrum** over the graft with suture anchors 7. **Capsular shift** to address redundancy **Closure Considerations:** In revision setting, ensure secure closure as tissues may be attenuated. Consider augmenting repairs with additional sutures. **Postoperative:** Longer immobilization (6 weeks in sling) given revision nature and bone grafting. No posterior-directed loads for 3 months. This is a 6-12 month recovery for return to rugby. **Counseling:** I would counsel the patient that revision surgery has **higher failure rates** (10-20%) than primary surgery, and return to contact sport may require 9-12 months. Some restrictions on high-risk activities may be permanent. } keyPoints={[ "Revision case with bone loss requires open approach", "Posterior approach provides direct access for bone grafting", "Expect scarring and difficult dissection in revision setting", "Bone graft (iliac crest or allograft) to restore glenoid arc", "Fix graft with screws parallel to glenoid face", "Repair labrum over graft with suture anchors", "Capsular shift addresses soft tissue redundancy", "Longer immobilization (6 weeks) for revision and bone graft", "Higher failure rate in revision (10-20%)", "Return to contact sport 9-12 months" ]} traps={[ "Attempting arthroscopic management with this degree of bone loss", "Underestimating difficulty of revision dissection", "Not planning for bone graft needs preoperatively", "Inadequate graft fixation", "Rushing rehabilitation after revision" ]} followUp={["What are the alternatives to posterior bone block for glenoid bone loss?", "How do you harvest iliac crest bone graft?"]} /> Thank you. This is a critical complication - **intraoperative axillary nerve injury** from excessive deltoid split. I need to act immediately and systematically. **Recognition:** Loss of deltoid tone during surgery is a **warning sign of axillary nerve injury**. The nerve has been injured either by direct trauma (laceration) or stretch from retraction. By extending the deltoid split to 8cm, I have exceeded the safe zone (5cm below posterolateral acromion) and likely injured the axillary nerve which runs 5-7cm from this landmark. **Immediate Management:** **Stop and Assess:** - Stop all dissection immediately - Remove all retractors - Allow tissues to relax - Assess what happened (how far did split extend, what instruments were used) **Nerve Exploration:** - I need to **identify and assess the axillary nerve** - Extend exposure inferiorly in controlled fashion to visualize nerve - The nerve exits the quadrangular space and runs along inferior border of teres minor - Trace nerve from quadrangular space laterally **Assessment of Injury:** If nerve is **in continuity** (intact but stretched): - This is likely neuropraxia or axonotmesis - Prognosis for recovery is good if nerve is intact - No immediate repair needed - Document in operative note If nerve is **transected** (lacerated): - This is neurotmesis - worst injury - Options: (1) Primary repair if clean transaction and no tension, (2) Tag nerve ends and plan delayed repair in 3-4 weeks - If tension-free primary repair possible: microsurgical repair with 8-0 or 9-0 nylon - If not possible: tag ends with vessel loops or sutures and close **Complete Planned Surgery:** After addressing nerve, I would still need to complete the locked dislocation reduction if possible, but may need to modify approach. **Documentation:** Meticulous operative note documenting: - Mechanism of injury - Assessment of nerve (in continuity vs transected) - Management performed - Prognosis discussed with patient **Postoperative:** - Immediate discussion with patient and family about complication - Full disclosure of injury - Referral to peripheral nerve specialist - EMG/NCS at 3-4 weeks to assess severity - If transected and tagged, plan delayed repair at 3-4 weeks - If in continuity, observe for 3-6 months for recovery - Physical therapy to prevent shoulder stiffness **Prevention for Future:** This injury was **preventable** by adhering to the **5cm safe zone** for deltoid splitting. This case reinforces the critical importance of this anatomic landmark. } keyPoints={[ "Loss of deltoid tone indicates axillary nerve injury", "Cause: excessive deltoid split beyond safe zone (5cm limit)", "Immediate action: stop, remove retractors, assess", "Explore and identify the axillary nerve", "Trace nerve from quadrangular space to assess continuity", "In continuity: likely neuropraxia, good prognosis, observe", "Transected: primary repair if no tension, or tag for delayed repair", "Complete operative note with full documentation", "Immediate disclosure to patient and family", "EMG/NCS at 3-4 weeks to assess injury severity", "Nerve surgery referral", "This was preventable - 5cm deltoid split limit is absolute" ]} traps={[ "Not recognizing the injury intraoperatively", "Continuing surgery without addressing nerve", "Attempting repair under tension", "Not documenting injury thoroughly", "Not disclosing complication to patient", "Not learning from complication to prevent recurrence" ]} followUp={["What is the expected recovery timeline for axillary nerve neuropraxia?", "What are the tendon transfer options for permanent axillary nerve palsy?"]} /> {/* SECTION 14: MCQ PRACTICE POINTS */} **Q: What is the internervous plane for the posterior approach to the shoulder?** A: Between **infraspinatus** (supplied by suprascapular nerve) and **teres minor** (supplied by axillary nerve). This is a true internervous plane providing safe access to the posterior shoulder. **Q: What nerve is at highest risk during the posterior approach to the shoulder, and how is it protected?** A: The **axillary nerve** is at highest risk. It courses approximately **5-7cm below the posterolateral corner of the acromion**. Protection requires limiting deltoid split to **no more than 5cm** below this landmark. **Q: What is the primary indication for open posterior approach to the shoulder in modern practice?** A: **Revision posterior instability with bone loss** requiring bone grafting. Most primary posterior labral repairs are now performed arthroscopically. Open posterior approach is reserved for bone loss, revision cases, and posterior glenoid fractures. **Q: What patient position is most commonly used for the posterior approach to the shoulder?** A: **Lateral decubitus** position on the opposite side, with the arm supported in slight flexion and internal rotation. This provides excellent posterior access and allows gravity to assist with exposure. **Q: A patient develops inability to abduct the shoulder after posterior approach surgery. What nerve is injured and how did it occur?** A: **Axillary nerve** injury causing deltoid paralysis. Most common mechanism is **excessive deltoid split** extending beyond the safe zone (more than 5cm below posterolateral acromion), leading to direct nerve injury or excessive retraction. {/* SECTION 15: AUSTRALIAN CONTEXT */} **Clinical practice in Australia:** **Subspecialty care:** - Posterior shoulder approaches typically performed by shoulder subspecialists - Complex cases (revision instability, fractures) often referred to tertiary centers - Arthroscopic posterior stabilization more common in general practice **Training considerations:** - Posterior approach less commonly encountered in training than deltopectoral - Important to recognize indications and refer appropriately - Cadaveric courses available for surgical approach training **Imaging access:** - CT and MRI readily available for preoperative planning - 3D CT reconstruction helpful for glenoid bone loss assessment - Access to advanced imaging in public and private systems **Operative considerations:** - Position lateral decubitus or prone depending on surgeon preference - Equipment for bone grafting (iliac crest harvest or allograft) should be available - Revision cases may require bone graft planning For FRACS exams, be prepared to describe the **internervous plane** (infraspinatus and teres minor), **safe deltoid split limits** (5cm below posterolateral acromion), and **primary indications** for the approach (posterior instability with bone loss, posterior glenoid fractures). Understanding the **axillary nerve anatomy** and protection is essential. {/* SECTION 16: EXAM CHEAT SHEET */}

Posterior Approach to the Shoulder

Posterior Approach to the Shoulder