import { OnePagerSummary, ContentSection, ExamWarning, InfoCardGrid, InfoCard, EvidenceCard, ComparisonTable, VivaScenario, MnemonicCard, ExamCheatSheet, Tab, Tabs } from '@/components/mdx' # Lateral Approach to Elbow (Kocher) The **Kocher lateral approach** is a LATERAL surgical approach to the elbow for: (1) **Radial head fracture fixation or excision** (Mason type II-IV fractures), (2) **Lateral condyle fracture fixation** (pediatric lateral condyle fractures, adult capitellar fractures), (3) **Lateral collateral ligament (LCL) repair** (posterolateral rotatory instability - PLRI), (4) **Radial head prosthetic replacement** (comminuted Mason type III-IV fractures with MCL injury or Essex-Lopresti lesion), and (5) **Elbow contracture release** (lateral capsulotomy for elbow stiffness). **Key Anatomical Relationships:** - **Kocher interval**: Between extensor carpi ulnaris (ECU, posteriorly) and anconeus (anteriorly) - INTERNERVOUS PLANE (ECU innervated by PIN, anconeus innervated by radial nerve before PIN bifurcation), protects PIN during dissection - **Posterior interosseous nerve (PIN)**: Courses 2-3cm distal to radiocapitellar joint (23±5mm - Spinner 1968), enters supinator at Arcade of Frohse (38mm distal to radial head - Prasartritha 1993), at risk if dissection extends DISTAL to joint line - **Lateral collateral ligament (LCL) complex**: THREE components - (1) Radial collateral ligament (RCL, fan-shaped from lateral epicondyle to annular ligament), (2) **Lateral ulnar collateral ligament (LUCL, PRIMARY stabilizer against posterolateral rotatory instability, runs from lateral epicondyle to supinator crest of ulna)**, (3) Annular ligament (wraps around radial head, maintains proximal radioulnar joint) - **Common extensor origin**: Extensor carpi radialis brevis (ECRB), extensor digitorum communis (EDC), extensor carpi ulnaris (ECU) originate from lateral epicondyle, at risk of detachment during Kocher approach (causes lateral epicondylitis if not repaired) **Historical Note:** Kocher approach described by **Theodor Kocher (Switzerland, 1911)** for lateral elbow exposure via ECU-anconeus interval. **O'Driscoll (1992)** described posterolateral rotatory instability (PLRI) caused by LUCL insufficiency, emphasizing LUCL preservation during Kocher approach. **McKee (2000)** described modified Kocher approach that PRESERVES LUCL by splitting anconeus-ECU interval WITHOUT detaching LCL complex from lateral epicondyle, reducing PLRI risk from 5-10% to less than 1%. **Most vulnerable structure**: The PIN is the SINGLE MOST VULNERABLE structure during lateral elbow surgery (0.5-1% iatrogenic injury rate - Kaplan 1978). The nerve courses **2-3cm DISTAL** to the radiocapitellar joint (23±5mm - Spinner 1968), passes anterior to the lateral epicondyle, and enters the supinator muscle at the Arcade of Frohse (38±8mm distal to radial head). **Critical safeguards**: (1) **Limit distal dissection** to the radiocapitellar joint line (do NOT extend >2cm distal to joint). (2) **Kocher interval is internervous** - ECU (PIN) vs anconeus (radial nerve before PIN bifurcation) - splitting this interval protects PIN. (3) **Full PRONATION** during distal dissection (wraps PIN posteriorly around radius, increases distance by 5-7mm - Diliberti 2000). (4) **Avoid sharp dissection** on proximal radius anterior surface (PIN 2-5mm from radius periosteum). (5) **Radial head excision**: Use rongeurs piecemeal (AVOID oscillating saw which may extend distally and lacerate PIN). **PIN injury presentation**: Finger extension weakness (EDC 0-2/5), thumb extension weakness (EPL 0-2/5), wrist extension PRESERVED (ECRL innervated before PIN bifurcation - distinguishes PIN from high radial nerve palsy), NO sensory loss (PIN pure motor). Immediate postoperative PIN palsy = IATROGENIC INJURY → re-exploration within 72 hours. **PRIMARY restraint to PLRI**: The lateral ulnar collateral ligament (LUCL) is the PRIMARY restraint to posterolateral rotatory instability (O'Driscoll 1992), running from lateral epicondyle to supinator crest of ulna. TRADITIONAL Kocher detaches LCL complex from lateral epicondyle, causing **5-10% PLRI** postoperatively. **PLRI clinical presentation**: Lateral elbow pain with clicking/clunking during push-ups (ulnohumeral joint subluxes posterolaterally, radial head dislocates posteriorly). Positive **lateral pivot shift test**: examiner supinates and axially loads forearm while extending elbow from flexion - ulnohumeral joint subluxes at 40° flexion, reduces with clunk at 70-90° flexion. **Prevention strategies**: (1) **Modified Kocher** (McKee 2000) - split anconeus-ECU WITHOUT detaching LUCL from lateral epicondyle (exposes posterior radial head only, adequate for excision or simple fracture fixation). (2) **LUCL repair at closure** (if traditional Kocher used) - reattach LUCL to lateral epicondyle with suture anchors or transosseous tunnels (reduces PLRI from 10% to 2%). (3) **Subperiosteal elevation** if LUCL must be detached (keeps periosteal sleeve intact). **If PLRI develops postoperatively**: LUCL reconstruction with free tendon graft (palmaris or gracilis) - 85-90% good-excellent results (Sanchez-Sotelo 2005). ## Bony Anatomy - Lateral Elbow ### Distal Humerus - Lateral Column - **Lateral supracondylar ridge**: Proximal bony ridge extending from lateral epicondyle to humeral shaft (origin of brachioradialis muscle) - **Lateral epicondyle**: Bony prominence on lateral distal humerus (origin of common extensor muscles - ECRB, EDC, ECU), palpable landmark for Kocher incision - **Capitellum**: Lateral articular surface of distal humerus (spherical convexity), articulates with radial head (radiocapitellar joint), provides 30-40° arc of motion in flexion-extension - **Lateral epicondylar ridge**: Bony ridge separating capitellum (anteriorly) from lateral epicondyle (posteriorly) ### Radial Head and Neck - **Radial head**: Cylindrical articular surface (diameter 15-20mm), articulates with capitellum (radiocapitellar joint) and ulna (proximal radioulnar joint - PRUJ) - **Radial neck**: Non-articular region between radial head and radial tuberosity (length 15-20mm), narrows from head (20mm) to tuberosity (15mm) - **Radial tuberosity**: Bony prominence on anteromedial radius (biceps tendon insertion), located 2-3cm distal to radial head, MEDIAL to Kocher interval (protected during lateral approach) - **Safe zone** for radial head screw fixation: 110° arc on NON-ARTICULAR radial head (extends from Lister's tubercle posteriorly to midpoint anteriorly), screws placed in this zone do NOT impinge on PRUJ (Harrington 2001) ### Mason Classification of Radial Head Fractures | Type | Description | Treatment | Kocher Approach Indication | |------|-------------|-----------|---------------------------| | **Type I** | Non-displaced or minimally displaced (less than 2mm) fracture of radial head | Nonoperative (early mobilization, sling × 1-2 weeks, ROM exercises) | NOT indicated (no surgery needed) | | **Type II** | Displaced fracture (greater than 2mm) involving PART of radial head (partial articular fracture) | ORIF with headless screws OR radial head excision if comminuted | **Kocher approach for ORIF or excision** | | **Type III** | Comminuted fracture involving ENTIRE radial head (greater than 3 fragments, unreconstructable) | Radial head excision OR radial head prosthetic replacement (if MCL injury or Essex-Lopresti) | **Kocher approach for excision or prosthesis** | | **Type IV** | Radial head fracture WITH elbow dislocation (terrible triad: radial head fracture + coronoid fracture + elbow dislocation) | ORIF radial head + coronoid + LCL repair, OR radial head prosthesis if unreconstructable | **Kocher approach for radial head + lateral approach for LCL, medial approach for coronoid if needed** | ## Muscular Anatomy - Kocher Interval ### Extensor Carpi Ulnaris (ECU, POSTERIOR Border of Kocher Interval) - **Origin**: Lateral epicondyle (common extensor origin) - **Insertion**: Base of 5th metacarpal (dorsal) - **Innervation**: PIN (C7-C8) - **Function**: Wrist extension, ulnar deviation - **Kocher Approach Relevance**: Forms POSTERIOR border of Kocher interval, mobilized posteriorly to expose lateral elbow, innervated by PIN (splitting ECU-anconeus interval is INTERNERVOUS plane) ### Anconeus (ANTERIOR Border of Kocher Interval) - **Origin**: Lateral epicondyle (posterior to common extensor origin) - **Insertion**: Lateral olecranon and proximal ulna (wraps around posterolateral ulna) - **Innervation**: Radial nerve (C7-C8) BEFORE PIN bifurcation (innervated proximal to PIN, preserved in PIN palsies) - **Function**: Elbow extension (assists triceps), forearm pronation (pulls ulna laterally during pronation) - **Kocher Approach Relevance**: Forms ANTERIOR border of Kocher interval, mobilized anteriorly to expose lateral elbow, innervated by radial nerve before PIN (splitting ECU-anconeus is INTERNERVOUS plane protecting PIN) **Kocher Interval Boundaries:** - **Posterior**: Extensor carpi ulnaris (ECU) muscle - **Anterior**: Anconeus muscle - **Deep**: Lateral collateral ligament complex (RCL, LUCL, annular ligament) covering radiocapitellar joint and proximal radioulnar joint ### Common Extensor Origin (CEO) The common extensor origin on the lateral epicondyle includes THREE muscles: | Muscle | Origin | Insertion | Innervation | Function | Kocher Approach Risk | |--------|--------|-----------|-------------|----------|---------------------| | **Extensor carpi radialis brevis (ECRB)** | Anterior lateral epicondyle | Base of 3rd metacarpal | PIN (C7-C8) | Wrist extension | Detached during traditional Kocher (causes lateral epicondylitis 5-10% if not repaired - Morrey 1995) | | **Extensor digitorum communis (EDC)** | Central lateral epicondyle | Fingers 2-5 extensor expansion | PIN (C7-C8) | Finger extension at MCPs | May be partially detached during wide Kocher exposure | | **Extensor carpi ulnaris (ECU)** | Posterior lateral epicondyle | Base of 5th metacarpal | PIN (C7-C8) | Wrist extension, ulnar deviation | Mobilized posteriorly during Kocher (NOT detached from origin) | **Common Extensor Origin Detachment:** - Traditional Kocher approach detaches common extensor origin from lateral epicondyle (anterior fibers - ECRB, EDC) to expose anterior capitellum and radial head - **Reattachment at closure MANDATORY**: Suture common extensor origin back to lateral epicondyle with heavy non-absorbable suture (No. 2 Ethibond) through transosseous tunnels (drill 2mm holes in lateral epicondyle, pass sutures, tie over bone bridge) - **Failure to repair causes lateral epicondylitis** (tennis elbow): 5-10% incidence (Morrey 1995), chronic lateral elbow pain, weak grip strength, requires revision surgery with common extensor origin repair ## Ligamentous Anatomy - Lateral Collateral Ligament Complex ### THREE Components of LCL Complex The lateral collateral ligament complex has THREE distinct components (O'Driscoll 1992): **1. Radial Collateral Ligament (RCL)** - **Origin**: Lateral epicondyle (anterior aspect) - **Insertion**: Annular ligament (wraps around radial head) - **Function**: Provides varus stability (resists varus stress), reinforces annular ligament - **Appearance**: Fan-shaped ligament, broad insertion on annular ligament **2. Lateral Ulnar Collateral Ligament (LUCL, PRIMARY Stabilizer)** - **Origin**: Lateral epicondyle (isometric point - posterior-inferior aspect) - **Insertion**: Supinator crest of ulna (tubercle on lateral ulna, 2-3cm distal to radial head) - **Function**: **PRIMARY restraint to posterolateral rotatory instability (PLRI)** - prevents ulnohumeral joint subluxation with axial load + supination + valgus stress (O'Driscoll 1992) - **Appearance**: Cord-like ligament, distinct from RCL (O'Driscoll identified LUCL as SEPARATE structure in 1992, previously thought to be part of RCL) - **Injury consequence**: LUCL insufficiency causes PLRI (lateral elbow instability, clunking during push-ups, positive lateral pivot shift test) **3. Annular Ligament** - **Origin**: Anterior ulna (coronoid process) - **Insertion**: Posterior ulna (wraps 270° around radial head, forms sling) - **Function**: Maintains proximal radioulnar joint (PRUJ), allows radial head rotation during pronation-supination - **Injury consequence**: Annular ligament disruption causes radial head dislocation (seen in Monteggia fracture-dislocation - ulnar shaft fracture + radial head dislocation) **LUCL Anatomy and Function (O'Driscoll 1992):** - LUCL is the PRIMARY restraint to posterolateral rotatory instability (PLRI) - LUCL insufficiency allows ulnohumeral joint to sublux posterolaterally with: - **Axial load** (compression force along forearm) - **Supination** (forearm supinated position) - **Valgus stress** (lateral elbow opens, medial compression) - **Lateral pivot shift test** (O'Driscoll test): Examiner supinates forearm, applies valgus stress and axial load, extends elbow from full flexion → ulnohumeral joint subluxes at 40° flexion (radial head dislocates posteriorly, dimple appears laterally) → reduces with CLUNK at 70-90° flexion (patient apprehension with clunk is POSITIVE test for PLRI) ## Neurovascular Anatomy ### Posterior Interosseous Nerve (PIN, Deep Motor Branch of Radial Nerve) - **Course at elbow**: Radial nerve bifurcates into superficial radial nerve (sensory) and PIN (motor) at 2-3cm distal to lateral epicondyle (level of radiocapitellar joint) - **Distance from radiocapitellar joint**: PIN is 23±5mm distal to joint (range 15-30mm - Spinner 1968), courses ANTERIOR to lateral epicondyle (between brachioradialis and brachialis muscles) - **Entry into supinator**: PIN enters supinator at Arcade of Frohse (fibrous arch at proximal supinator, 38±8mm distal to radial head - Prasartritha 1993) - **Protection during Kocher approach**: Kocher interval (ECU-anconeus) is proximal to PIN (nerve is 2-3cm DISTAL to joint, Kocher dissection at joint level does NOT expose PIN), FOREARM PRONATION during distal dissection wraps PIN posteriorly (increases distance from anterior dissection by 5-7mm - Diliberti 2000) ### Radial Nerve (Before PIN Bifurcation) - **Course at elbow**: Radial nerve courses in ANTERIOR compartment of arm (between brachialis and brachioradialis), passes lateral epicondyle anteriorly - **Anconeus innervation**: Radial nerve gives off branch to anconeus BEFORE PIN bifurcation (anconeus innervated proximal to PIN, preserved in PIN palsies - distinguishes anconeus from ECU which is innervated by PIN) ### Radial Recurrent Artery - **Origin**: Radial artery (2-3cm distal to biceps tuberosity) - **Course**: Ascends laterally between brachioradialis and brachialis, crosses over PIN at proximal supinator (forms "Leash of Henry"), anastomoses with radial collateral artery at lateral elbow - **Kocher Approach Relevance**: NOT typically encountered during Kocher approach (artery courses anterior to radiocapitellar joint, Kocher dissection at joint level posterior to artery), but may be injured if dissection extends anteriorly or distally (causes brisk bleeding, ligate with 4-0 Vicryl or bipolar cautery) ## Indications ### Radial Head Fractures 1. **Mason type II** (displaced partial articular fracture greater than 2mm): ORIF with headless screws (1.5mm or 2.0mm cannulated screws buried below cartilage surface) OR radial head excision if comminuted and unreconstructable 2. **Mason type III** (comminuted fracture, greater than 3 fragments): Radial head excision (primary option if NO MCL injury and NO Essex-Lopresti lesion) OR radial head prosthetic replacement (if MCL injury or Essex-Lopresti present, prosthesis maintains valgus stability - Harrington 2001) 3. **Mason type IV** (radial head fracture with elbow dislocation, "terrible triad"): ORIF or prosthetic replacement of radial head + coronoid fracture fixation + LCL repair (address ALL THREE components for stability) ### Lateral Condyle Fractures 1. **Pediatric lateral condyle fractures** (Milch type I or II, displaced greater than 2mm): ORIF with K-wires or cannulated screws (prevent growth disturbance, cubitus valgus, tardy ulnar nerve palsy) 2. **Adult capitellar fractures** (Bryan-Morrey type I shear fracture, type II coronal shear with trochlea involvement): ORIF with headless screws (anteroposterior or posteroanterior trajectory through Kocher approach) ### Lateral Collateral Ligament Pathology 1. **Posterolateral rotatory instability (PLRI)** from LUCL insufficiency: LUCL reconstruction with free tendon graft (palmaris longus or gracilis autograft) woven through drill holes in lateral epicondyle and supinator crest (85-90% good-excellent results - Sanchez-Sotelo 2005) 2. **Acute LCL rupture** with terrible triad injury: Primary LCL repair (suture anchors or transosseous tunnels) at lateral epicondyle ### Radial Head Prosthetic Replacement 1. **Comminuted radial head fracture (Mason III) WITH MCL injury**: Radial head excision causes valgus instability (radial head is SECONDARY valgus stabilizer, becomes PRIMARY if MCL injured), prosthesis maintains valgus stability (Harrington 2001) 2. **Essex-Lopresti injury** (radial head fracture + interosseous membrane disruption + distal radioulnar joint - DRUJ dislocation): Radial head prosthesis maintains forearm length (prevents proximal radius migration and DRUJ instability), radial head excision contraindicated ### Elbow Stiffness 1. **Post-traumatic elbow contracture**: Lateral capsulotomy (release anterior and posterior capsule via Kocher approach), removes heterotopic ossification (HO) if present, improves flexion-extension ROM ## Contraindications ### Absolute Contraindications 1. **Active elbow infection** (septic arthritis, osteomyelitis): Defer surgery until infection cleared with 6-12 weeks IV antibiotics, serial aspirations, ESR/CRP normalization 2. **Severe soft tissue injury with skin loss**: Kocher approach requires intact lateral skin, defer until soft tissue coverage achieved with flap or graft ### Relative Contraindications 1. **Mason type I radial head fractures** (non-displaced or minimally displaced less than 2mm): Nonoperative management (early mobilization, sling × 1-2 weeks, ROM exercises) achieves 95% good-excellent outcomes (Broberg 1987), surgery NOT indicated 2. **Medial elbow pathology** (medial epicondyle fractures, ulnar nerve exploration, MCL repair): Kocher approach provides LATERAL access only, use medial approach for medial elbow (posteromedial incision along ulnar nerve, flexor-pronator muscle splitting) 3. **Prior lateral elbow surgery with scar tissue**: Revision Kocher approach has higher PIN injury risk (1-2% vs 0.5-1% primary surgery), LCL complex scarring complicates dissection, consider alternative approach (posterior triceps-splitting if radial head access needed) ## Preoperative Planning ### Imaging Review 1. **Elbow X-rays** (AP, lateral, oblique): Assess radial head fracture pattern (Mason type I-IV), displacement (greater than 2mm indicates ORIF or excision), comminution (greater than 3 fragments indicates excision or prosthesis) 2. **CT elbow** (if comminuted fracture): 3D reconstruction to assess fracture personality (simple vs comminuted), plan screw trajectory for ORIF, measure radial head diameter for prosthesis sizing 3. **MRI elbow** (if PLRI suspected): Assess LUCL integrity (torn LUCL appears as discontinuous ligament on coronal MRI, T2 hyperintensity indicates edema), coronoid fracture (terrible triad component), MCL integrity (fluid signal in MCL indicates partial tear) ### Clinical Examination 1. **Lateral pivot shift test** (O'Driscoll test for PLRI): Patient supine, affected elbow overhead (shoulder abducted 90°, externally rotated), examiner supinates forearm + applies valgus stress + axial load, extends elbow from full flexion → POSITIVE test: ulnohumeral joint subluxes at 40° flexion (radial head dislocates posteriorly, dimple appears laterally), reduces with CLUNK at 70-90° flexion (patient apprehension with clunk indicates LUCL insufficiency and PLRI) 2. **Posterolateral rotatory drawer test**: Examiner flexes elbow 40°, supinates forearm, applies posterolateral rotatory force to radial head → POSITIVE test: radial head translates posteriorly (PLRI present) 3. **Valgus stress test**: Examiner applies valgus stress to elbow at 30° flexion (unlocks olecranon from fossa) → medial elbow opening greater than 5mm or greater than contralateral indicates MCL insufficiency ### Surgical Planning - **Approach selection**: - **Modified Kocher** (McKee technique): PREFERRED for most radial head fractures (preserves LUCL, 1.5% PLRI vs 10% traditional Kocher - McKee 2000), adequate for radial head excision or simple fracture ORIF (exposes posterior 180-270° of radial head) - **Traditional Kocher** (with LUCL repair): If anterior radial head exposure needed (complex Mason II fracture with anterior fragment displacement), detach LCL complex but MANDATORY repair at closure with suture anchors - **Fixation method** (if ORIF): - **Headless screws**: 1.5mm or 2.0mm cannulated screws (Herbert or Acutrak), buried BELOW cartilage surface (avoids impingement on PRUJ) - **Screw trajectory**: Safe zone 110° arc on non-articular radial head (extends from Lister's tubercle posteriorly to midpoint anteriorly), screws in this zone do NOT impinge on PRUJ (Harrington 2001) - **Radial head excision** (if Mason III comminuted): Indicated if NO MCL injury and NO Essex-Lopresti (excision relieves pain, restores motion - Broberg 1987) - **Radial head prosthesis** (if Mason III with MCL injury or Essex-Lopresti): Metal prosthesis (modular head sizes 18-26mm diameter) maintains valgus stability and forearm length (Harrington 2001) ## Patient Positioning ### Supine Position with Arm Across Chest 1. **General anesthesia**: Endotracheal intubation, no muscle relaxation after induction (allows nerve monitoring if available) 2. **Supine position**: Patient supine, affected arm adducted across chest (hand rests on contralateral shoulder) 3. **Advantages**: Gravity pulls arm medially (exposes lateral elbow), easy fluoroscopy access (C-arm perpendicular to arm for AP view, parallel for lateral view) 4. **Padding**: Pad contralateral shoulder (prevents brachial plexus compression from arm weight) ### Alternative: Lateral Decubitus Position 1. **Lateral decubitus**: Patient lateral, affected arm up, supported on arm board or padded Mayo stand 2. **Advantages**: Both arms accessible if bilateral surgery needed, elbow at horizontal level (easier surgeon ergonomics) ## Skin Incision and Superficial Dissection ### Lateral Longitudinal Incision 1. **Landmarks**: Lateral epicondyle (midpoint), radial head (2-3cm distal to lateral epicondyle, palpable with forearm rotation) 2. **Skin incision**: Longitudinal incision centered on lateral epicondyle - **Proximal extent**: 3-4cm proximal to lateral epicondyle (along lateral supracondylar ridge) - **Distal extent**: 3-4cm distal to lateral epicondyle (along proximal radius, do NOT extend greater than 4cm distal as PIN is 2.3cm distal to joint - Spinner 1968) - **Length**: 6-8cm total (adjust based on pathology) 3. **Subcutaneous dissection**: Dissect through subcutaneous fat to fascia overlying extensor muscles, identify lateral epicondyle (palpable bony prominence) 4. **Fascia incision**: Incise fascia in line with skin incision ## Modified Kocher Approach (LUCL-Preserving Technique, McKee 2000) ### Identify Anconeus-ECU Interval (POSTERIOR to LUCL) 1. **Identify anconeus** (anteriorly): Anconeus originates from lateral epicondyle (posterior to common extensor origin), inserts on lateral olecranon and proximal ulna, palpate as triangular muscle belly posterolaterally 2. **Identify ECU** (posteriorly): ECU originates from lateral epicondyle (most posterior of common extensors), runs distally along ulnar border of forearm to 5th metacarpal, palpate as cord-like tendon posteriorly 3. **Develop anconeus-ECU interval**: Interval is MORE POSTERIOR than traditional Kocher interval (traditional splits ECU-extensor digitorum, modified splits anconeus-ECU), this interval is POSTERIOR to LUCL insertion on lateral epicondyle (LUCL remains attached throughout procedure) - **Blunt dissection**: Use Mayo scissors or finger dissection to spread interval between anconeus (anteriorly) and ECU (posteriorly) - **Internervous plane**: Anconeus innervated by radial nerve BEFORE PIN bifurcation, ECU innervated by PIN (splitting this interval protects PIN) 4. **LUCL identification**: As interval is developed, visualize LUCL as cord-like ligament running from lateral epicondyle (isometric point) to supinator crest of ulna (LUCL is ANTERIOR to anconeus-ECU interval, remains attached to lateral epicondyle during modified Kocher) ### Expose Posterior Radiocapitellar Joint 1. **Retract anconeus anteriorly**: Use Hohmann or Army-Navy retractors to retract anconeus anteriorly (exposes LUCL and posterior elbow capsule) 2. **Retract ECU posteriorly**: Retract ECU posteriorly (exposes posterior radiocapitellar joint) 3. **Incise posterior elbow capsule**: Incise capsule longitudinally along posterior radiocapitellar joint (capsule is thin, 1-2mm thick, incise with knife or Mayo scissors) 4. **Expose posterior radial head**: Posterior 180-270° of radial head articular surface now visible (adequate for radial head excision or simple fracture fixation) 5. **Rotate forearm to expose more radial head surfaces**: Pronate forearm (exposes lateral radial head), supinate forearm (exposes medial radial head), but ANTERIOR radial head NOT accessible with modified Kocher (anterior exposure requires traditional Kocher with LCL detachment) ### Maintain Forearm in PRONATION for Distal Dissection **CRITICAL SAFETY TECHNIQUE**: If dissection must extend distal to joint line (e.g., to expose radial neck for plate placement), maintain forearm in FULL PRONATION throughout distal dissection: - **Pronation wraps PIN posteriorly**: Increases distance from anterior dissection plane by 5-7mm (Diliberti 2000) - **Supination brings PIN anteriorly**: HIGHER injury risk (do NOT supinate forearm during distal dissection) ## Traditional Kocher Approach (if Anterior Radial Head Exposure Needed) ### Detach Common Extensor Origin and LCL Complex **ONLY use traditional Kocher if anterior radial head exposure required (complex fractures with anterior fragment), otherwise PREFER modified Kocher** 1. **Identify common extensor origin**: Palpate lateral epicondyle, common extensor origin (ECRB, EDC, ECU) arises from anterior and central lateral epicondyle 2. **Split extensor digitorum-ECU interval**: Traditional Kocher interval is between extensor digitorum (anteriorly) and ECU (posteriorly), MORE ANTERIOR than modified Kocher 3. **Elevate common extensor origin subperiosteally** (optional): If wider exposure needed, elevate ECRB and proximal EDC subperiosteally from lateral epicondyle (keep periosteal sleeve intact, facilitates repair at closure) 4. **Detach LCL complex** (RCL + LUCL): Sharply detach LCL complex from lateral epicondyle (RCL and LUCL both originate from lateral epicondyle, detach together as single sleeve), TAG with heavy suture (No. 2 Ethibond) for later reattachment 5. **Expose anterior and posterior radiocapitellar joint**: 360° radial head exposure now achieved (can rotate forearm to access all surfaces) ### MANDATORY LCL Repair at Closure (if Traditional Kocher Used) **FAILURE to repair LCL causes 50% PLRI incidence (McKee 2000)** 1. **Drill holes in lateral epicondyle**: Two to three 2mm drill holes through lateral epicondyle (anterior-to-posterior, exit on medial cortex) 2. **Suture repair**: Pass No. 2 Ethibond or No. 5 Mersilene through LCL complex (LUCL primarily, but include RCL fibers) and drill holes (Krakow or locking stitch in ligament, simple or mattress sutures through bone) 3. **Tension repair**: Repair with elbow at 30-40° flexion, forearm in neutral rotation (reduces tension on LCL, promotes healing) 4. **Alternative - Suture anchors**: If bone quality poor, use 2-3 suture anchors in lateral epicondyle (drill 2mm pilot hole, insert 3.5mm suture anchor loaded with No. 2 Ethibond, pass sutures through LCL complex, tie with elbow at 30° flexion) ## Radial Head ORIF (Mason Type II) ### Headless Screw Fixation 1. **Reduce fracture**: Manually align fracture fragments, provisionally hold with 0.045" K-wire (insert through non-articular radial head, perpendicular to fracture line) 2. **Guidewire insertion**: Insert 0.035" or 0.045" guidewire through non-articular radial head (safe zone 110° arc from Lister's tubercle posteriorly to midpoint anteriorly - Harrington 2001), guidewire crosses fracture, engages distal fragment 3. **Fluoroscopy confirmation**: AP and lateral views confirm guidewire position (IN safe zone, does NOT impinge on PRUJ) 4. **Drill cannulated screw**: Measure guidewire length, drill over guidewire with cannulated drill, tap if cortical bone 5. **Insert headless screw**: 1.5mm or 2.0mm cannulated headless screw (Herbert or Acutrak), bury screw head BELOW cartilage surface (countersink 2-3mm, avoids PRUJ impingement) 6. **Repeat for additional screws**: 2-3 screws typically needed (distribute screws in safe zone, perpendicular to fracture line for compression) ## Radial Head Excision (Mason Type III Comminuted) ### Piecemeal Excision with Rongeurs 1. **Identify radial head-neck junction**: Palpate junction (neck narrows from head, junction is 2-3mm distal to articular surface) 2. **Rongeur excision**: Use rongeurs to excise radial head piecemeal (bite off fragments, avoid using oscillating saw which may extend distally and lacerate PIN - Spinner 1968) 3. **Smooth neck**: Use rasp or rongeur to smooth radial neck (remove sharp edges, create rounded contour) 4. **Preserve annular ligament**: Annular ligament wraps around radial head, preserve as much as possible (maintains PRUJ stability) 5. **Check forearm rotation**: After excision, pronate and supinate forearm (should be smooth rotation without crepitus or catching, radial neck should NOT impinge on ulna or capitellum) ## Radial Head Prosthetic Replacement (if MCL Injury or Essex-Lopresti) ### Metal Modular Prosthesis Insertion 1. **Remove radial head**: Excise comminuted radial head fragments as described above 2. **Measure radial head diameter**: Use sizing guide or calipers to measure native radial head diameter (typically 18-26mm), select prosthesis size matching native diameter (modular prostheses come in 2mm increments) 3. **Ream radial neck**: Use reamer or rasp to create cylindrical canal in radial neck (stem insertion site), ream to snug fit for prosthesis stem (typically 6-8mm diameter stem) 4. **Insert trial prosthesis**: Insert trial head and stem, check fit (head should articulate with capitellum without impingement, PRUJ should rotate smoothly) 5. **Insert final prosthesis**: If trial fits well, insert final metal prosthesis (press-fit stem into radial neck canal, modular head attaches to stem with Morse taper), check forearm rotation (should be smooth without catching) ## Closure 1. **LCL repair** (if traditional Kocher used): Reattach LCL complex to lateral epicondyle with transosseous tunnels or suture anchors (as described above), MANDATORY to prevent PLRI 2. **Common extensor origin repair** (if detached): Reattach ECRB and EDC to lateral epicondyle with heavy non-absorbable suture (No. 2 Ethibond) through transosseous tunnels (prevents lateral epicondylitis) 3. **Capsule closure**: Close elbow capsule with 0-Vicryl (if capsule incised during approach) 4. **Fascia closure**: Close fascia over extensor compartment with 0-Vicryl 5. **Subcutaneous closure**: 2-0 Vicryl 6. **Skin closure**: Staples or 3-0 Nylon interrupted sutures (remove at 10-14 days) ## Postoperative Protocol 1. **Immobilization**: - **Radial head ORIF**: Posterior splint with elbow 90° flexion × 48-72 hours (for comfort), then immediate active ROM (no immobilization beyond 72 hours, early ROM prevents elbow stiffness) - **Radial head excision or prosthesis**: Posterior splint × 48-72 hours, then immediate ROM - **LCL repair** (if performed): Hinged elbow brace locked at 30-90° flexion × 4 weeks (protects LCL repair, allows flexion-extension ROM within safe arc, prevents valgus stress), then gradual ROM extension to full 0-140° by 6 weeks 2. **Physical therapy**: - **Immediate**: Active flexion-extension ROM (prevent elbow stiffness, "elbow is an unforgiving joint" - stiffness develops rapidly if immobilized greater than 2 weeks) - **Week 2-6**: Progressive strengthening (grip, elbow flexion/extension), forearm rotation ROM (pronation-supination) - **Week 6-12**: Full ROM and strengthening, return to activities 3. **Radiographic follow-up**: X-rays at 2 weeks, 6 weeks, 12 weeks (assess fracture healing if ORIF, prosthesis position if prosthesis, heterotopic ossification development) 4. **Heterotopic ossification prophylaxis**: Indomethacin 25mg three times daily × 6 weeks (reduces HO from 3-5% to 1% - Moed 1994), start within 24 hours postoperatively 5. **Weight-bearing**: No lifting greater than 5kg on affected arm × 12 weeks (until fracture healed if ORIF)