import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Exits greater sciatic notch 25-40mm proximal to tip of greater trochanter, runs between gluteus medius and minimus **Protection**: Stay within 5cm distal to GT tip (safe zone), never extend muscle split proximally beyond this landmark, use anterior-based approach to avoid **Location**: Runs 20-30mm posterior to hip joint capsule, posterior to short external rotators (piriformis is key landmark - nerve 2cm posterior) **Protection**: Tag external rotators for identification, gentle retraction only, limit retraction time, avoid leg lengthening greater than 4cm **Location**: Lies 40-60mm anterior/medial to acetabulum, within femoral triangle (NAVEL: nerve, artery, vein, empty space, lymphatics) **Protection**: Anterior retractors must stay on bone (ilium/acetabular rim), never slide medially into soft tissue, avoid anteroinferior acetabular screws **Location**: Run along pelvic brim anteriorly, 15-25mm anterior to anterior acetabular wall, separated by psoas and iliacus muscles **Protection**: No screws in anteroinferior quadrant of acetabulum, screws posterosuperior only, medial wall reaming must be controlled to avoid perforation **Location**: Runs deep to quadratus femoris muscle, supplies femoral head via retinacular vessels, critical for femoral head viability **Protection**: Preserve quadratus femoris when possible, recognize already disrupted in AVN cases, gentle handling of posterior capsule ## Indications for Primary THA ### Primary Indications **End-stage Hip Osteoarthritis** - Primary idiopathic OA (most common in elective setting) - Failed conservative management (analgesia, activity modification, physiotherapy) - Radiographic evidence: joint space loss, osteophytes, subchondral sclerosis, cysts - Pain limiting activities of daily living, night pain, functional disability **Secondary Osteoarthritis** - Developmental dysplasia of hip (DDH) - complex reconstruction, often requires specialized cups - Avascular necrosis - consider THA vs resurfacing in younger patients - Post-traumatic arthritis - previous acetabular or femoral fracture - Slipped upper femoral epiphysis sequelae - Perthes disease sequelae in adults **Inflammatory Arthritis** - Rheumatoid arthritis - often bilateral, bone quality poor, younger age group - Ankylosing spondylitis - fixed spinal deformity affects cup positioning - Psoriatic arthritis **Acute Fracture** - Displaced intracapsular NOF in elderly (>75 years, low demand) - THA vs hemiarthroplasty: THA if independent, mobile, good life expectancy ### Contraindications **Absolute** - Active local or systemic infection - Inadequate soft tissue coverage - Neurogenic arthropathy (Charcot joint) - relative, high failure rate - Severe peripheral vascular disease with ischaemic limb **Relative** - Poor bone stock (severe osteoporosis, prior irradiation) - Skeletal immaturity - Medical comorbidities precluding surgery - Non-compliance with postoperative restrictions - Progressive neurological disease affecting lower limb ### Preoperative Planning **Templating Requirements** - Calibrated digital or analogue templating essential - Template both AP pelvis and lateral femur - Determine cup size, position (restore center of rotation) - Determine stem size, neck length, offset - Plan for leg length restoration (measure from teardrop to lesser trochanter bilaterally) - Identify bone defects requiring augmentation **Australian Context - AOANJRR Data** - Uncemented cups used in 90% of primary THA - Cemented stems in 35%, uncemented 60%, hybrid 5% - Ceramic-on-polyethylene most common bearing (40%) - Metal-on-polyethylene 35%, ceramic-on-ceramic 15% - 10-year revision rate: 6.5% for primary OA **AOANJRR Pearl**: "In Australia, uncemented acetabular components account for 90% of primary THA. For femoral stems, younger patients (less than 65) typically receive uncemented stems, while cemented stems are preferred in elderly patients greater than 75 years with osteoporotic bone. Hybrid fixation (uncemented cup, cemented stem) is the gold standard for fracture indications." ## Critical Surgical Anatomy ### Osseous Landmarks **Acetabulum** - **Transverse acetabular ligament**: Marks inferior rim, key landmark during reaming - **Teardrop**: Radiographic landmark, medial wall reference point - **Anterior wall**: Protects external iliac vessels, femoral neurovascular bundle - **Posterior wall**: Must preserve 40-50% for stability, protects sciatic nerve - **Columns**: Anterior (iliopubic) and posterior (ilioischial) - biomechanical support **Proximal Femur** - **Piriformis fossa**: Entry point for broaching, defines starting point - **Greater trochanter**: Abductor insertion (gluteus medius, minimus via conjoint tendon) - **Lesser trochanter**: Iliopsoas insertion, landmark for neck cut (1cm proximal) - **Calcar femorale**: Medial cortical thickening, provides stability for stem - **Femoral neck**: Anteversion 10-15°, neck-shaft angle 130-135° ### Neurovascular Structures - Distances Critical for Exam **Superior Gluteal Nerve** - Exits greater sciatic notch 25-40mm proximal to GT tip - Runs between gluteus medius and minimus - Supplies gluteus medius, minimus, tensor fascia lata - Injury causes irreversible Trendelenburg gait - **Safe zone**: Stay greater than 5cm distal to GT tip **Inferior Gluteal Nerve** - Enters gluteus maximus 20-30mm inferior to piriformis - Supplies gluteus maximus exclusively - Protected by splitting muscle in line with fibers **Sciatic Nerve** - Passes 20-30mm posterior to hip joint capsule - Located 2cm posterior to piriformis tendon - Most at risk during posterior approach (0.5-2% injury rate) - Injury risk increased with: leg lengthening greater than 4cm, revision surgery, dysplasia - Combination of tibial and common peroneal divisions **Femoral Nerve** - Lies within femoral triangle (NAVEL) 40-60mm anteromedial to joint - At risk with aggressive anterior retractor placement - Protected by keeping retractors on bone (anterior wall/ilium) **Vascular Structures** - **External iliac artery and vein**: 15-25mm anterior to anterior acetabular wall, at risk with anteroinferior screws - **Medial femoral circumflex artery**: Deep to quadratus femoris, supplies femoral head - **Profunda femoris**: Posterior to femur, at risk during femoral preparation ### Muscular Anatomy - Posterior Approach **Gluteus Maximus** - Dual innervation: superior gluteal nerve (superior 1/3) and inferior gluteal nerve (inferior 2/3) - Split in line with fibers = TRUE internervous plane - Hip extensor, assists with external rotation **Short External Rotators (Superior to Inferior)** 1. **Piriformis**: Key landmark (sciatic nerve 2cm posterior) 2. **Superior gemellus**: Forms conjoined tendon with OI 3. **Obturator internus**: Strong external rotator 4. **Inferior gemellus**: Forms conjoined tendon 5. **Quadratus femoris**: Covers medial femoral circumflex artery **Gluteus Medius and Minimus** - Primary hip abductors - Supplied by superior gluteal nerve - At risk in lateral and anterolateral approaches - Detachment causes abductor deficiency and limp **Internervous Plane Pearl**: "The posterior approach to the hip is the only TRUE internervous plane. Gluteus maximus is split in line with fibers - the muscle has dual innervation from superior and inferior gluteal nerves, so splitting it preserves all muscle function. Other approaches (lateral, anterolateral) split or detach muscles from single nerve supplies." ## Step-by-Step Surgical Technique ### Step 1: Patient Positioning & Preparation **Posterior Approach Positioning** - Lateral decubitus position, affected hip uppermost - Pelvis perpendicular to floor, secured with anterior/posterior supports - Both supports padded to prevent pressure injury - Dependent leg flexed at hip and knee, pillow between legs - Upper leg free to move for dislocation - Support at sacrum and symphysis pubis **Direct Anterior Approach Positioning** - Supine on traction or fracture table - Perineal post for counter-traction - Both legs draped free - C-arm positioned for AP and lateral fluoroscopy **Landmarks to Mark** - Greater trochanter - Anterior superior iliac spine - Posterior superior iliac spine - Femoral shaft axis **Positioning Pearl**: "For the posterior approach, I position the patient in lateral decubitus with the pelvis PERPENDICULAR to the floor - this is critical for accurate cup positioning. I use anterior and posterior pelvic supports at the pubis and sacrum. The dependent leg is flexed to relax the sciatic nerve. I verify position before draping using a pelvic positioner or intraoperative fluoroscopy." - Inadequate pelvic stabilization → cup malposition (most common cause of dislocation) - Brachial plexus injury from arm malposition (check pulse, position arm at less than 90° abduction) - Peroneal nerve injury of dependent leg (check padding over fibular head) - Pressure injuries (sacrum, heel, malleoli) - Pelvic rotation during case → leg length discrepancy, cup malposition ### Step 2: Skin Incision & Superficial Dissection (Posterior Approach) **Incision** - Curved incision 10-15cm (shorter for minimally invasive, longer for complex cases) - Centered on greater trochanter - Extends proximally toward PSIS - Curves distally along femoral shaft axis - Straight lateral in line with femur for direct lateral approach **Fascial Layer** - Incise fascia lata in line with skin incision - Identify gluteus maximus muscle fibers (oblique orientation) - Split gluteus maximus IN LINE with fibers - Use blunt dissection (fingers or Cobb) to develop plane - This is a TRUE internervous plane (dual innervation) **Internervous Plane Pearl**: "I split gluteus maximus in line with its fibers - this is a true internervous plane because the muscle has dual innervation. The superior third is supplied by the superior gluteal nerve and the inferior two-thirds by the inferior gluteal nerve. Splitting preserves all motor function." - Sciatic nerve lies deep to gluteus maximus (posterior to short external rotators) - Inferior gluteal neurovascular bundle enters proximal gluteus maximus (stay in distal 2/3) - Cutting across muscle fibers causes denervation and weakness - Superior gluteal nerve at risk if dissection extends greater than 5cm proximal to GT ### Step 3: Deep Dissection - Short External Rotators **Identification of Short External Rotators (Superior → Inferior)** 1. Piriformis (most superior, sciatic nerve 2cm posterior) 2. Superior gemellus 3. Obturator internus (strong tendon, forms conjoined tendon with gemelli) 4. Inferior gemellus 5. Quadratus femoris (most inferior, covers medial circumflex artery) **Technique** - Place deep retractors (Hohmann) anterior and posterior to expose rotators - Palpate sciatic nerve posterior to piriformis (protect with retractor) - Tag each tendon with heavy suture BEFORE cutting (essential for repair) - Detach piriformis from posterior femur/GT - Detach conjoined tendon (superior gemellus + OI + inferior gemellus) - May preserve quadratus femoris (protects medial circumflex artery) - Alternatively, perform inside-out technique (detach from capsule instead of femur) **External Rotator Pearl**: "I tag each short external rotator tendon with a heavy absorbable suture BEFORE cutting - this allows anatomic repair at closure. I identify them superior to inferior: Piriformis, Superior gemellus, Obturator internus, Inferior gemellus, Quadratus femoris. The sciatic nerve is 2cm posterior to the piriformis - I protect it throughout. Some surgeons preserve quadratus femoris to protect the medial femoral circumflex artery." - **Sciatic nerve** (0.5-2% injury rate): Most common nerve injury in THA, located 2cm posterior to piriformis - **Superior gluteal nerve**: At risk if dissection extends greater than 5cm proximal to GT - **Medial femoral circumflex artery**: Deep to quadratus femoris, already disrupted in AVN/fracture - Failure to tag tendons makes repair difficult/impossible ### Step 4: Capsulotomy & Hip Dislocation **Capsulotomy Technique** - Perform T-shaped or H-shaped capsulotomy - Tag capsular flaps with HEAVY sutures (2-0 or 0 absorbable) for later identification - Superior flap, inferior flap, and posterior flap - Leave adequate tissue for repair (at least 1cm margins) - Excise minimal capsule (most should be preserved for repair) **Hip Dislocation Maneuver** - Flex hip to 90° - Adduct across midline - Internally rotate - Apply gentle posterior force - Femoral head should deliver posteriorly - If difficult: increase flexion, check for osteophytes blocking dislocation **Head Removal** - Insert corkscrew into femoral head - Extract head with gentle rocking motion - Inspect head: wear pattern (superior pole), osteophytes, loose bodies - Send head for histology and microbiology **Capsular Repair Pearl**: "I perform a T-shaped capsulotomy and TAG all capsular flaps with heavy sutures - this is critical. At closure, I repair the capsule meticulously, which reduces dislocation rate from 3-5% to less than 1%. Multiple randomized trials support capsular repair. I preserve as much capsule as possible - don't excise, just incise and tag." - **Femoral shaft fracture** during forced dislocation (especially osteoporotic bone, elderly females) - **Acetabular fracture** (posterior wall) with vigorous levering - Not tagging capsule makes later identification and repair difficult or impossible - Sciatic nerve traction injury with excessive force ### Step 5: Femoral Neck Osteotomy **Level Determination** - Based on preoperative templating - Standard: 1cm above lesser trochanter - Horizontal cut at this level (perpendicular to shaft) - Angle of cut affects leg length and offset **Technique** - Use oscillating saw with narrow blade - Protect posterior soft tissues with retractor - Cut perpendicular to femoral shaft in coronal plane - Preserve calcar (medial cortical thickening) - provides stability - Remove femoral head with corkscrew extractor - Inspect cut surface for occult fracture lines - Elevate cut surface with retractor if needed for femoral exposure **Neck Cut Pearl**: "I make the femoral neck cut at the templated level, approximately 1cm above the lesser trochanter. A horizontal cut perpendicular to the shaft preserves the calcar and allows accurate leg length restoration. I inspect the cut surface carefully for occult fracture lines - if present, I may alter my fixation plan to cemented stem or use cerclage prophylactically." - Cut too DISTAL → short leg, abductor weakness (moment arm reduced) - Cut too PROXIMAL → long leg, nerve stretch injury, reduced ROM - Calcar fracture propagation into diaphysis - Thermal necrosis from prolonged sawing (cool with irrigation) - Sciatic nerve injury from saw exiting posteriorly ### Step 6: Acetabular Exposure & Preparation **Retractor Placement (3-point retraction)** - **Anterior retractor** (Hohmann): Over anterior wall/column, on bone - **Posterior retractor**: Over posterior wall/ischium, protect sciatic nerve - **Inferior retractor**: Into obturator foramen (blunt Hohmann) - This provides 360° visualization of acetabulum **Acetabular Preparation** - Excise labrum circumferentially - Remove osteophytes (especially inferior) - Identify transverse acetabular ligament (marks inferior extent) - Identify fovea (marks anatomic center) - On fluoroscopy: teardrop marks medial wall **Reaming Technique** - Start with smallest reamer (36-38mm typically) - Direct reamer toward ipsilateral shoulder (45° inclination, 15° anteversion) - Ream progressively (2mm increments) - Ream MEDIALLY to subchondral bone (bleeding cancellous bone) - Goal: restore anatomic center of rotation (level of teardrop) - Ream to achieve peripheral rim contact - Final reamer size determines cup size (cup is 1-2mm larger for press-fit) **Acetabular Reaming Pearl**: "I place three retractors for 360° visualization: anterior, posterior, and inferior in the obturator foramen. The transverse acetabular ligament marks the inferior extent - this is my key anatomical landmark. I ream medially to restore the anatomic center of rotation at the level of the teardrop. Progressive reaming until I achieve bleeding subchondral bone with peripheral rim contact. Final reamer plus 1-2mm determines my cup size for press-fit." - **Medial wall perforation** → intrapelvic migration, vascular injury (especially protrusio acetabuli) - **Posterior wall deficiency** from over-reaming → instability, need for augmentation - **External iliac vessels** anterior to acetabulum (15-25mm from anterior wall) - **Sciatic nerve** posterior, at risk with inferior retractor malposition - Superior gluteal neurovascular bundle exits sciatic notch superiorly ### Step 7: Acetabular Component Insertion **Cup Selection** - Cup diameter = final reamer + 1-2mm (for press-fit, line-to-line fit) - Larger diameter if bone quality poor or revision setting - Consider augments/cages for significant defects **Lewinnek Safe Zone Positioning** - **Inclination**: 40-45° (radiographic angle) - **Anteversion**: 15-20° - Use alignment guides, referenced to transverse ligament and patient position - Fluoroscopy can confirm position **Insertion Technique** - Impact cup with straight impactor aligned to handle - Aim for peripheral rim contact (avoid central perforation) - Impact until solid seating (change in pitch of impact sound) - Assess stability: no rocking or toggle - Supplemental screws ONLY if stability suboptimal **Screw Placement (if needed)** - POSTEROSUPERIOR quadrant only (safe zone) - Avoid anteroinferior quadrant (vascular structures) - Screws directed into ilium/posterior column - Usually 2-3 screws sufficient - Avoid intra-articular penetration **Lewinnek Safe Zone Pearl**: "I position the cup within the Lewinnek safe zone: 40-45° inclination and 15-20° anteversion. Studies show cups within this zone have 1.5% dislocation rate vs 6.1% outside the zone. However, safe zone is not absolute - I also consider combined anteversion concept: cup anteversion plus stem anteversion should equal 25-45° for optimal stability and impingement-free range of motion." - **Cup malposition** → dislocation (most common cause of early dislocation) - **Excessive anteversion** (greater than 25°) → anterior dislocation - **Insufficient anteversion** (less than 10°) → posterior dislocation - **Anteroinferior screws** → external iliac vessel injury (potentially fatal) - **Central perforation** → intrapelvic component migration, need for revision - Vertical cup (greater than 50° inclination) → accelerated polyethylene wear, edge loading ### Step 8: Femoral Exposure & Preparation **Femoral Delivery** - Place anterolateral retractor (Hohmann) around femoral neck - Elevate/deliver proximal femur into wound - Flex, externally rotate, and extend hip to deliver femur - Remove anterior/superior osteophytes that impede visualization **Canal Preparation** - Start with box chisel in piriformis fossa (defines entry point) - Direct handle LATERALLY (prevents varus stem alignment) - Clear soft tissue from canal opening - Use canal finder to confirm canal direction **Broaching Technique** - Start with smallest broach (size 1 or 2) - Direct handle laterally (prevents varus) - Progressive broaching (don't skip sizes) - Each broach should advance 2-3mm deeper than previous - Continue until cortical contact achieved (metaphyseal fill for uncemented) - Firm seating without advancement = final broach size - Target 10-15° anteversion (match native femoral version) **Version Assessment** - Palpate lesser trochanter (should be posteromedial) - Broach handle should point toward patella with hip extended - Can use trial stem with version guide **Broaching Pearl**: "I start with a box chisel in the piriformis fossa, directing the handle LATERAL - this is critical to prevent varus stem alignment. Progressive broaching without skipping sizes, each broach advancing 2-3mm deeper. I achieve metaphyseal fill and cortical contact for uncemented fixation. I target 10-15° anteversion matching native femoral version. Combined anteversion (cup + stem) should equal 25-45°." - **Varus stem alignment** (broach handle too medial) → reduced offset, instability, early loosening - **Calcar fracture** (excessive force, tight fit) → may need cerclage wire or cable - **Femoral perforation** (misdirected broach, bowed femur) → bleeding, cement leak, instability - **Greater trochanter fracture** (excessive soft tissue tension) → abductor dysfunction - **Anterior cortical perforation** (excessive anteversion) → need for cement containment or revision ### Step 9: Trial Reduction & Stability Assessment **Trial Component Insertion** - Insert trial stem matching final broach size - Attach trial head (start with standard neck length, typically +0mm to +4mm) - Trial polyethylene liner in acetabular shell **Hip Reduction** - Extend hip - Apply traction - Gentle internal rotation - Head should reduce with minimal force - "Clunk" indicates seating **Systematic Stability Testing - STABLE Mnemonic** 1. **Anterior stability test**: Full extension + 40° external rotation → should remain reduced 2. **Posterior stability test**: 90° flexion + 40° internal rotation + adduction → should remain reduced 3. **Impingement assessment**: Take hip through full ROM, check for bony or prosthetic impingement 4. **Stability in all positions**: Check stability at various points in arc of motion **Leg Length Assessment** - With knees flexed: overlap patellae (crude but effective) - Measure from fixed pelvic point (ASIS or iliac crest) to medial malleolus - Compare to preoperative measurement and contralateral side - Goal: within 5mm of contralateral or preoperative plan - Adjust by changing head size (+/- 4mm) or neck length (+/- 8-12mm) **Offset Assessment** - Palpate tension of abductors - Greater offset → more tension → better stability but risk of trochanteric pain - Insufficient offset → laxity → instability **Stability Testing Pearl**: "I perform systematic stability testing using STABLE: Test anterior stability with full extension and 40° external rotation - this is the position at risk for anterior dislocation with DAA. Test posterior stability with 90° flexion, 40° internal rotation, and adduction - the position at risk for posterior dislocation with posterior approach. I assess leg length by overlapping patellae with knees flexed - goal is within 5mm discrepancy." - Inadequate stability testing → postoperative dislocation (most preventable complication) - Leg length discrepancy greater than 1cm → patient dissatisfaction, nerve stretch, litigation - Excessive offset → trochanteric bursitis, abductor pain, iliotibial band friction - Insufficient offset → instability, impingement, early dislocation - Failure to check impingement → late dislocation from component wear/impingement ### Step 10: Final Component Insertion **Trial Removal** - Dislocate hip (same maneuver as initial dislocation) - Remove trial head - Extract trial stem with slap hammer - Deliver femur anteriorly for visualization **Uncemented Stem Insertion** - Clean canal with dry sponge - Final stem same size as final broach - Insert stem by hand initially - Impact with mallet (straight impactor on trunion) - Avoid varus/valgus malalignment - Seat to planned depth (reference to GT or shoulder of stem) - Confirm version (10-15° anteversion) **Cemented Stem Insertion (Modern Cementing Technique)** 1. Insert cement restrictor at isthmus (2cm beyond stem tip) 2. Pulsatile lavage with 3L saline (clean canal) 3. Dry canal thoroughly (ribbon gauze, suction) 4. Vacuum-mixed cement (reduce porosity) 5. Retrograde cement gun application (fill from distal to proximal) 6. Pressurization with cement pressurizer 7. Insert stem in slight anteversion (10-15°) 8. Hold in position until cement hardens 9. Remove excess cement while still soft 10. Goal: 2-3mm cement mantle circumferentially **Femoral Head Insertion** - Modular head (size and length determined from trialing) - Clean trunion with dry sponge (no fluid - affects locking) - Align head with trunion - Impact firmly with head impactor (change in sound indicates seating) - Check for proper seating (no gap between head and neck) **Final Hip Reduction** - Extend hip, apply traction, gentle internal rotation - Confirm reduction **Modern Cementing Technique Pearl**: "For cemented stems, I use modern cementing technique developed by Charnley and refined over decades: cement restrictor at the isthmus, pulsatile lavage with 3L saline, dry canal thoroughly, vacuum-mixed cement to reduce porosity, retrograde gun application from distal to proximal, pressurization, then stem insertion. This achieves optimal cement mantle of 2-3mm circumferentially. AOANJRR data shows excellent results with cemented stems in elderly patients greater than 75 years." - **Poor cement mantle** (less than 2mm) → early loosening, cement fracture - **Air in cement** → porosity, reduced strength (use vacuum mixing) - **Fat embolism** during cementing → hypoxia, cardiovascular collapse (vent canal, use restrictor) - **Component not fully seated** → subsidence, early failure - **Femoral head not properly seated** → dissociation, pain, metallosis ### Step 11: Final Stability Check & Wound Inspection **Final Stability Assessment** - Repeat stability tests with permanent components - Anterior: extension + 40° ER - Posterior: 90° flexion + 40° IR + adduction - Full ROM without impingement - Hip should be stable throughout entire arc of motion **Impingement Check** - Flexion to 110-120° (no anterior impingement) - Extension to neutral (no posterior impingement) - Internal rotation in flexion (no impingement) - External rotation in extension (no impingement) - Identify any bony prominences causing impingement **Wound Inspection** - Pulse lavage with 3L normal saline (or antibiotic solution) - Inspect for: (1) fractures (acetabular, femoral), (2) cement debris, (3) loose bodies - Achieve meticulous hemostasis (electrocautery, bone wax for bleeding cancellous bone) - Check sciatic nerve if any concern (visual inspection, gentle palpation) **Final Check Pearl**: "I perform comprehensive final stability testing with the permanent components in place. I check full ROM to ensure no impingement - flexion to 110-120°, extension to neutral, full rotation. I pulse lavage with 3L saline for thorough debridement. Meticulous hemostasis is critical - hematoma increases infection risk. I verify no intraoperative fractures before closure." - **Unrecognized intraoperative fracture** → displacement, subsidence, early failure - **Hematoma** from inadequate hemostasis → infection risk, delayed rehabilitation - **Component instability** missed during final check → early dislocation - **Sciatic nerve injury** not recognized → delayed diagnosis, poor outcome ### Step 12: Layered Closure & Hip Precautions **Critical Capsular Repair** - Identify tagged capsular flaps - Repair capsule with interrupted heavy absorbable sutures (2-0 or 0) - At least 5-6 sutures for robust repair - Ensure adequate tension (not too tight, not too loose) - Evidence: reduces dislocation from 3-5% to less than 1% **External Rotator Repair** - Identify tagged external rotator tendons - Repair piriformis to posterior femur/GT - Repair conjoined tendon (superior gemellus + OI + inferior gemellus) - Use heavy absorbable sutures through bone tunnels or to soft tissue - Restore anatomic tension **Fascial and Muscle Closure** - Repair gluteus maximus fascia with absorbable sutures (1 or 0) - Running or interrupted technique - Ensure no dead space **Subcutaneous and Skin Closure** - Subcutaneous layer with 2-0 absorbable (reduces seroma) - Skin: staples OR subcuticular absorbable suture - Apply sterile dressing - Consider waterproof dressing for early mobilization **Hip Precautions (Posterior Approach)** - **NO hip flexion greater than 90°** for 6 weeks - **NO adduction past midline** for 6 weeks - **NO internal rotation** for 6 weeks - Use elevated toilet seat, avoid low chairs - Sleep with pillow between legs - These precautions protect capsular and rotator repair **Capsular Repair Pearl**: "I meticulously repair the posterior capsule with heavy absorbable sutures - this is the single most important step for preventing dislocation. Multiple RCTs show capsular repair reduces dislocation from 3-5% to less than 1%. I also repair the short external rotators to restore the posterior soft tissue envelope. Hip precautions for 6 weeks protect this repair: no flexion greater than 90°, no adduction past midline, no internal rotation." - **No capsular repair** → 3-4 times higher dislocation rate (from less than 1% to 3-5%) - **Inadequate external rotator repair** → posterior instability - **Non-compliance with hip precautions** → early dislocation (most common in first 6 weeks) - **Wound closure under excessive tension** → wound dehiscence, necrosis - **Dead space** → hematoma formation, infection risk ## Complications of Primary THA ### Additional Complications **Heterotopic Ossification (HO)** - 10-30% incidence - Brooker Classification: Grade 1 (islands), Grade 2 (1cm gap between bone and HO), Grade 3 (less than 1cm gap), Grade 4 (ankylosis) - Risk factors: male, hypertrophic OA, DISH, prior HO, neurological disorders - Prevention: indomethacin 25mg TDS for 6 weeks, or single-dose radiation (700 cGy within 72 hours) - Management: if symptomatic (restricted ROM, pain), excision after maturation (12-18 months), with prophylaxis **Vascular Injury** - rare (less than 0.1%) - External iliac artery/vein: from anteroinferior acetabular screws, medial wall perforation - Recognition: hemodynamic instability, expanding hematoma, absent distal pulses - Prevention: avoid anteroinferior screws, controlled medial reaming - Management: immediate vascular surgery consultation, repair vs bypass **Abductor Weakness/Trendelenburg Gait** - More common with lateral/anterolateral approaches (detach abductors) - Superior gluteal nerve injury (extend split greater than 5cm proximal to GT) - Prevention: minimize abductor detachment, repair abductors anatomically, protect superior gluteal nerve - Management: physiotherapy, gait training, cane, rarely abductor reconstruction ## Post-operative Management ### Immediate Post-operative (Day 0-1) **Analgesia** - Multimodal approach: paracetamol 1g QDS, NSAID (celecoxib 200mg BD), opioid (oxycodone PRN) - Regional anesthesia: spinal or epidural (preferred), reduces opioid requirement - Local infiltration analgesia (LIA): local anesthetic + epinephrine + ketorolac into capsule, muscles - Patient-controlled analgesia (PCA) if needed **VTE Prophylaxis** - Australian guidelines: aspirin 100mg daily OR rivaroxaban 10mg daily OR enoxaparin 40mg daily - Duration: 35 days for THA (extended prophylaxis) - Mechanical: TED stockings, intermittent pneumatic compression intraoperatively and first 24 hours - Early mobilization most important **Wound Care** - Waterproof dressing allows showering - Check for drainage (should be minimal) - Remove drain when output less than 30mL/24 hours (usually day 1) **Mobilization** - Day 0: sit out of bed, static exercises - Day 1: stand and mobilize with physiotherapy, walking frame or crutches - Weight bearing: usually full weight bearing as tolerated (WBAT) for uncemented - Partial weight bearing (PWB) if cemented stem or intraoperative fracture **Hip Precautions (Posterior Approach)** - No hip flexion greater than 90° (use elevated toilet seat, avoid low chairs) - No adduction past midline (pillow between legs when sleeping) - No internal rotation (avoid crossing legs) - Duration: 6 weeks (protects capsular repair) ### Short-term Recovery (Week 1-6) **Week 2 Follow-up** - Wound inspection, remove sutures/staples (if not dissolvable) - Check XR: AP pelvis and lateral hip (confirm component position, no fracture) - Assess mobilization, pain control - Reinforce hip precautions **Week 6 Follow-up** - Clinical examination: ROM, stability, abductor strength, leg length - XR: AP pelvis and lateral hip (baseline for future comparison) - Discontinue hip precautions (if capsular repair performed) - Progress to full activities as tolerated - Return to driving (if off opioids, good control, adequate ROM) ### Long-term Follow-up **Australian Guidelines (AOANJRR Recommendations)** - **1 year**: clinical and radiographic review - **5 years**: clinical and radiographic review - **10 years**: clinical and radiographic review - **Lifetime surveillance**: AOANJRR registry participation **Radiographic Assessment** - AP pelvis (both hips for comparison) - Lateral affected hip - Assess: component position, radiolucent lines, osteolysis, subsidence, heterotopic ossification **Return to Activities** - **6 weeks**: driving, gentle activities (walking, swimming, golf) - **3 months**: return to work (sedentary), cycling, most daily activities - **6 months**: return to sport (avoid high-impact: running, jumping) - **Recommended**: walking, swimming, golf, cycling, doubles tennis - **Avoid**: running, high-impact aerobics, contact sports ### Outcomes - Australian Data (AOANJRR) **Survival Rates (Primary OA Indication)** - 5 years: 96.5% - 10 years: 94% - 15 years: 90% - 20 years: 85% **Reasons for Revision** 1. Aseptic loosening (30%) 2. Infection (20%) 3. Dislocation/instability (18%) 4. Periprosthetic fracture (15%) 5. Liner/head wear (10%) 6. Other (7%) **Patient-Reported Outcomes** - Pain relief: 95% significant improvement - Function: 90% satisfied with function - Quality of life: significant improvement in EQ-5D, SF-36 - Return to work: 85% of working-age patients **Australian Context** - Medicare MBS items: 49318 (primary THA unilateral), 49319 (bilateral staged) - PBS medications: VTE prophylaxis (rivaroxaban), analgesia (tramadol, oxycodone) - AOANJRR: world's largest joint replacement registry, mandatory reporting since 2002 **AOANJRR Outcomes Pearl**: "Based on Australian data from the AOANJRR registry, primary THA has excellent outcomes with 96.5% survival at 5 years and 94% at 10 years for primary OA. The most common reasons for revision are aseptic loosening, infection, and dislocation. Uncemented cups are used in 90% of cases, while femoral fixation varies by patient age - uncemented for younger, cemented for elderly greater than 75 years. Patient satisfaction is high with 95% achieving significant pain relief." ## References 1. Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations after total hip-replacement arthroplasties. J Bone Joint Surg Am. 1978;60(2):217-220. *Classic study defining the safe zone for acetabular component positioning (40-45° inclination, 15-20° anteversion) that reduces dislocation rates from 6.1% to 1.5%.* 2. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA; 2023. *Comprehensive registry data showing 90% uncemented cups, 96.5% survival at 5 years, 94% at 10 years for primary THA in Australia.* 3. Kwon MS, Kuskowski M, Mulhall KJ, Macaulay W, Brown TE, Saleh KJ. Does surgical approach affect total hip arthroplasty dislocation rates? Clin Orthop Relat Res. 2006;447:34-38. *Systematic review demonstrating posterior approach has 2-5% dislocation rate, reduced to <1% with capsular repair, compared to anterior approach baseline <1%.* 4. Jolles BM, Zangger P, Leyvraz PF. Factors predisposing to dislocation after primary total hip arthroplasty: a multivariate analysis. J Arthroplasty. 2002;17(3):282-288. *Multivariate analysis identifying key risk factors: approach, component positioning, soft tissue repair, head size, patient factors (cognitive impairment, prior surgery).* 5. Dorr LD, Malik A, Wan Z, Long WT, Harris M. Precision and bias of imageless computer navigation and surgeon estimates for acetabular component position. Clin Orthop Relat Res. 2007;465:92-99. *Study on acetabular component positioning accuracy showing computer navigation improves precision but Lewinnek safe zone remains goal.* 6. Widmer KH, Zurfluh B. Compliant positioning of total hip components for optimal range of motion. J Orthop Res. 2004;22(4):815-821. *Introduced combined anteversion concept: cup anteversion plus stem anteversion should equal 25-45° for optimal stability and impingement-free ROM.* 7. Barrack RL. Dislocation after total hip arthroplasty: implant design and orientation. J Am Acad Orthop Surg. 2003;11(2):89-99. *Comprehensive review of factors affecting stability including component positioning, head size (larger head = greater jump distance), soft tissue repair.* 8. Pellicci PM, Bostrom M, Poss R. Posterior approach to total hip replacement using enhanced posterior soft tissue repair. Clin Orthop Relat Res. 1998;355:224-228. *Landmark study demonstrating capsular and external rotator repair reduces dislocation from 3-5% to <1% - changed practice globally.* 9. National Institute for Health and Care Excellence (NICE). Total hip replacement and resurfacing arthroplasty for end-stage arthritis of the hip. Technology appraisal guidance [TA304]. London: NICE; 2014. *UK guidelines on indications, patient selection, and outcomes for primary THA including cost-effectiveness analysis.* 10. Maloney WJ, Keeney JA. Leg length discrepancy after total hip arthroplasty. J Arthroplasty. 2004;19(4 Suppl 1):108-110. *Review of leg length discrepancy causes, prevention strategies (templating, intraoperative measurement), and management options (shoe lift, revision).*

Primary Total Hip Arthroplasty

Primary Total Hip Arthroplasty