import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Sciatic nerve**. Location: Posterior to hip joint, courses 15-30mm posterior to posterior capsule. Protection: Avoid excessive posterior retraction, gentle tissue handling, identify nerve in revision cases, avoid prolonged abnormal positioning during dislocation, limit leg lengthening to less than 15mm **Superior gluteal nerve and vessels**. Location: Exit pelvis through greater sciatic notch above piriformis, run between gluteus medius and minimus. Protection: Limit dissection to less than 5cm proximal to greater trochanter tip, avoid superior retractor migration, identify before extending incision proximally **Femoral neurovascular bundle**. Location: Anterior to hip joint, medial to anterior hip capsule and femoral neck. Protection: Careful placement of anterior acetabular retractor (stay on bone, not into pelvis), avoid anterior perforation during acetabular reaming, gentle medial capsular release **Obturator neurovascular bundle**. Location: Passes through obturator foramen inferior-medial to acetabulum. Protection: Avoid inferior acetabular retractor migration medially, careful inferior reaming, avoid screws in inferior quadrant **External iliac vessels**. Location: Anterior to hip joint along pelvic brim, at risk with anterior acetabular screws. Protection: Safe screw zones are anterosuperior (10-2 o'clock) and posterosuperior - avoid anterior horizontal screws, limit screw penetration to 20mm beyond cortex, use fluoroscopy for anterior screws **Patient Position**: Lateral decubitus position with affected side up. Pelvis stabilized with anterior support against pubis and posterior support against sacrum - must be perpendicular to floor (verify with level). All bony prominences well-padded including axillary roll caudal to axilla (not in axilla to avoid brachial plexus injury), pillows between knees, fibular head padding. Arms positioned on arm boards or chest support. Contralateral leg slightly flexed at hip and knee. **Surgical Approach**: Posterior approach (Moore/Southern) most common in Australia (approximately 60% per AOANJRR). Alternatively: Direct Anterior (20%), Hardinge lateral (15%), Watson-Jones anterolateral (5%). Posterior approach advantages: familiar anatomy, extensile, spares abductors. Disadvantages: higher dislocation risk without repair (10-15% vs 2-5% anterior), requires robust soft tissue repair. **Incision**: Curved incision centered over greater trochanter, extending 8-10cm proximally-posteriorly along gluteus maximus fibers, then 3-5cm distally along femoral shaft. Mark incision with skin marker before draping. ## Acetabular Exposure and Reaming Technique ### Exposure Principles Complete acetabular exposure requires three retractors in standard positions: **Anterior retractor (12 o'clock)**: Hohmann over anterior wall - stay on bone to avoid femoral vessels **Inferior retractor (3 o'clock left hip, 9 o'clock right hip)**: Broad retractor over inferior wall - protect obturator neurovascular bundle **Posterior retractor (6 o'clock)**: Hohmann around posterior wall - avoid excessive retraction (sciatic nerve 15-30mm posterior) ### Sequential Reaming Steps 1. **Remove all soft tissue**: Labrum circumferentially, osteophytes (especially posterior-inferior), ligamentum teres remnant, transverse acetabular ligament (TAL) can be preserved as version guide 2. **Start small**: Initial reamer 38-40mm typically, engage all quadrants 3. **Incremental progression**: Ream 2mm at a time until bleeding subchondral bone visible over greater than 70% of hemisphere 4. **Orientation**: 40-45° inclination (from horizontal), 15-20° anteversion (middle of safe zone is safest) 5. **Final size**: Under-ream by 1-2mm for press-fit (e.g., if final reamer is 56mm, use 54-55mm cup) ### Anatomic Landmarks for Version **Transverse acetabular ligament (TAL)**: Connects anterior and posterior horns of acetabulum, typically oriented 15-25° anteverted - useful intraoperative reference **Patient position**: If pelvis perpendicular to floor, cup aimed 15-20° anterior to coronal plane **Lateral decubitus reference**: Some surgeons use 45° from vertical as target (combines inclination and version) **Technical Tip**: EXAM KEY - Acetabular reaming goals are threefold: 1) Create hemisphere of bleeding subchondral bone for biological fixation (bony ingrowth), 2) Achieve accurate orientation within Lewinnek safe zone (30-50° inclination, 10-30° anteversion), 3) Maximize bone preservation (stay lateral to medial wall, avoid over-reaming). Common errors: medialization through floor (alters biomechanics, risks pelvic structures), excessive inclination over 50° (edge loading, accelerated wear), inadequate exposure (malposition). ### Press-Fit Principles Modern uncemented cups rely on initial press-fit stability (micromotion less than 50 microns allows ingrowth). Under-reaming by 1-2mm creates interference fit. Porous coating or hydroxyapatite promotes ingrowth. Supplemental screws provide initial stability but do not improve long-term fixation per AOANJRR data - use 2-3 screws in safe zones if concerned about initial stability. - Medialization through medial wall into pelvis (vascular injury, protrusio) - especially thin bone in inflammatory arthritis, protrusio, osteoporosis - Anterior retractor migration into pelvis (external iliac vessels, obturator vessels) - Excessive inclination over 50° (edge loading, increased wear, squeaking with ceramic) - Inadequate inclination under 30° (posterior instability, reduced cup coverage) - Excessive anteversion combined with anteverted stem (anterior instability) - Inadequate anteversion with retroverted stem (posterior instability) ## Femoral Canal Preparation and Stem Insertion ### Exposure of Proximal Femur After hip dislocation and femoral neck osteotomy, expose proximal femur: **Remove remaining neck**: Rongeur or osteotome to remove remaining neck back to base **Clear soft tissue**: Remove soft tissue from greater trochanter, calcar, and canal opening **Protect anteriorly**: Hohmann retractor over anterior femoral neck protects femoral vessels **Retract posteriorly**: Hohmann around posterior calcar improves visualization ### Canal Preparation Technique 1. **Open canal**: Box chisel or curved curette to open proximal canal - aim down femoral shaft axis (slight valgus, 10-15° anteversion) 2. **Canal finder**: Insert to confirm trajectory and version - should aim down canal without cortical impingement 3. **Sequential broaching**: Start small (size 1-3 depending on canal size), progressively increase until: - Tight metaphyseal fit (no toggle) - Broach shoulder/collar sits flush on calcar cut - Appropriate fill of metaphyseal flare 4. **Version assessment**: Most modern stems have built-in 10-15° anteversion - broach handle orientation indicates final stem version 5. **Stability test**: Final broach should not toggle with rotation or axial force ### Stem Design Considerations **Metaphyseal-filling stems** (e.g., Corail, Taperloc): Fill proximal metaphysis, load calcar, immediate press-fit stability, suit normal anatomy **Tapered wedge stems** (e.g., Accolade II): Progressive taper, rely on 3-point fixation, versatile for varied anatomy **Anatomic stems**: Replicate native femoral anatomy with offset, anteversion, version options **Technical Tip**: EXAM KEY - Femoral preparation goals: achieve stable metaphyseal press-fit (uncemented), correct version (combine with cup for total 25-50°), restore offset and leg length. Modern uncemented stems are metaphyseal-fitting (proximal fill, proximal load transfer) versus older diaphyseal-fitting stems. Combined anteversion concept: femoral stem anteversion plus acetabular cup anteversion should equal 25-50° (Ranawat safe zone) - if cup has 20° anteversion, stem should have 10-15° anteversion. Under-prepare canal (stem too proud) risks periprosthetic fracture. Over-prepare (stem too small) loses press-fit stability. ### Uncemented Stem Insertion **Final stem selection**: Typically same size as final broach or one size smaller (manufacturer-specific) **Coating types**: - Grit-blasted titanium (promotes friction and ingrowth) - Hydroxyapatite coating (enhances early bone apposition) - Porous coating (allows bony ingrowth into pores 100-400 microns) **Insertion technique**: Gentle impaction with mallet, avoid excessive force, assess seating with each blow, final position should match broach position exactly **Intraoperative fracture risk**: Higher in osteoporotic bone, varus femur, tight fit - consider cemented stem if very osteoporotic - Femoral perforation during broaching (especially anterior cortex in flexed femur, varus anatomy) - Periprosthetic fracture during stem insertion (osteoporotic bone, excessive force) - Excessive femoral anteversion combined with cup anteversion (anterior instability) - Inadequate anteversion with retroverted cup (posterior instability) - Stem not fully seated (proud stem, high shoulder increases fracture risk) - Over-reaming canal (loss of press-fit, subsidence, thigh pain) ## Implant Selection and Bearing Surfaces ### Acetabular Component Selection **Cup sizing**: Final reamed size minus 1-2mm for press-fit (e.g., 56mm reamer uses 54-55mm cup depending on manufacturer) **Porous coating**: Titanium plasma spray, trabecular metal, or porous titanium for ingrowth **Screw holes**: Multiple screw holes allow supplemental fixation - use 2-3 screws in safe zones if needed **Cup geometry**: Hemispherical cups most common, some designs have peripheral self-locking features ### Femoral Head Selection **Head size options**: - 28mm: Historical standard, lowest volumetric wear, highest dislocation risk (rarely used now) - 32mm: Standard for most primary THA, good stability-wear balance - 36mm: Increasingly popular, better stability (greater jump distance), minimal wear increase with HXLPE - 40mm: Very stable, consider for recurrent dislocation, some concern for volumetric wear **AOANJRR data**: 32mm and 36mm heads have similar low revision rates - both acceptable choices **Head offset**: Varies by manufacturer (short, standard, long, extra-long neck) - restore native offset for abductor tension and stability ### Bearing Surface Combinations Cobalt-chrome or ceramic head on highly cross-linked polyethylene liner. CURRENT STANDARD for most patients. AOANJRR shows lowest revision rates. HXLPE wear rate less than 0.05mm/year (versus 0.1-0.2mm/year for standard PE). Minimum liner thickness 6-7mm to prevent fracture. Ceramic head (alumina or zirconia-toughened alumina) on HXLPE liner. Lower wear than metal-on-HXLPE. Risk of ceramic head fracture (rare, less than 0.01%). Risk of squeaking 1-10% (patient dissatisfaction). Consider for young active patients. Alumina or delta ceramic head on ceramic liner. Lowest wear (less than 0.001mm/year). Risk of squeaking 5-10%, ceramic fracture less than 0.01%, stripe wear if impingement. Reserved for very young patients (under 50 years) with high activity demands. NOW OBSOLETE. Cobalt-chrome head on cobalt-chrome liner. High failure rates due to ARMD (adverse reaction to metal debris), pseudotumors, metallosis. No longer used for primary THA per AOANJRR recommendations. **Technical Tip**: EXAM KEY - Bearing surface selection based on patient factors. Young active patients (under 50): consider ceramic-on-HXLPE or ceramic-on-ceramic for lowest wear. Standard patients (50-75): metal head on HXLPE is evidence-based choice with best AOANJRR data. Elderly low-demand (over 75): standard polyethylene acceptable (cost savings, minimal wear concern in limited lifespan). Metal-on-metal is obsolete - do not use. HXLPE has revolutionized THA longevity - AOANJRR shows 30% reduction in revision versus standard PE at 10 years. ## Trialing and Stability Assessment ### Component Assembly for Trial 1. **Femoral component**: Final broach left in situ OR trial stem inserted (manufacturer-dependent) 2. **Trial head selection**: Select head size (32mm or 36mm typically) and offset (short/standard/long) based on preoperative templating 3. **Acetabular liner**: Already inserted in acetabular shell (HXLPE liner impacted and locked) 4. **Trial reduction**: Assemble components and reduce hip carefully ### Systematic Stability Testing **Posterior stability test** (most critical for posterior approach): - Hip in extension and neutral rotation - Apply posterior translation force on femur - Should have 40-50mm of excursion (translation) before head dislocates posteriorly - If dislocates easily: insufficient offset, cup malposition, or inadequate head size **Anterior stability test**: - Hip in extension and maximum external rotation - Apply anterior translation - Should not dislocate anteriorly (less common than posterior dislocation) **Impingement testing**: - Flex hip 90°, adduct 15°, internally rotate 70° (should not dislocate or impinge posteriorly) - Extend hip, externally rotate 40° (should not impinge anteriorly) - Full range screening: flexion 110°, extension 10°, abduction 45°, adduction 30°, IR/ER 40° in extension ### Leg Length Assessment **Clinical measurement**: - Compare knee heights with legs parallel and pelvis level - Palpate ASISs and compare distances to medial malleoli bilaterally - Can use ruler from ASIS to medial malleolus **Radiographic measurement**: Some surgeons use intraoperative fluoroscopy to measure from ischial tuberosity to lesser trochanter **Target**: Equal length or up to 5mm lengthening (overlengthening better tolerated than shortening for stability) **Nerve palsy risk**: Lengthening greater than 15mm significantly increases sciatic nerve palsy risk - revise if over-lengthened ### Offset Assessment **Clinical signs of appropriate offset**: - Good abductor tension (firm resistance when pulling leg inferiorly) - Hip feels stable with normal excursion - Normal soft tissue envelope tension **Insufficient offset**: Hip feels unstable, reduced excursion, soft tissue laxity, postoperative limp and instability **Excessive offset** (overstuffing): Limited ROM, tight reduction, increased soft tissue tension, postoperative pain **Technical Tip**: EXAM KEY - Trialing determines final implant success - DO NOT RUSH. Systematic assessment: 1) Stability testing (shuck test, ROM testing), 2) Leg length measurement (clinical and/or radiographic), 3) Offset assessment (abductor tension). If unstable posteriorly: increase offset with longer neck, increase cup anteversion (if not already excessive), larger head size, or consider constrained liner. If unstable anteriorly: decrease cup anteversion, larger head. If leg length discrepancy: adjust head size/length or stem size. Warn patient preoperatively that perfect leg length equality may not be possible if needed for stability. ## Wound Closure and Postoperative Protocol ### Soft Tissue Repair - Critical for Posterior Approach **External rotator repair**: - Using previously placed stay sutures in piriformis, obturator internus, gemelli - Repair to anatomic insertion on posterior greater trochanter - Use strong non-absorbable suture (Number 2 Ethibond or equivalent) - Place sutures through drill holes in greater trochanter if bone quality good - If osteoporotic bone: repair to soft tissue around vastus lateralis ridge **Posterior capsule repair**: - Repair capsule to rotator cuff remnant or greater trochanter - Some surgeons perform capsular plication (tighten capsule) for enhanced stability - Tie repairs with hip in neutral position (NOT flexed/internally rotated) **Evidence for repair**: Studies show dislocation rate 10-15% without posterior repair versus 2-4% with robust repair - repair is ESSENTIAL ### Layered Closure 1. **Gluteus maximus fascia**: Close with 0-Vicryl running or interrupted sutures 2. **Fascia lata and ITB**: Close with 0-Vicryl, ensure good fascial closure to prevent hernia 3. **Subcutaneous layer**: Close with 2-0 Vicryl to obliterate dead space 4. **Skin**: Staples (easier removal, good for obese patients) OR subcuticular absorbable suture (better cosmesis) - similar infection rates per evidence ### Drain Placement (Controversial) **Arguments against drains** (majority current practice): - No reduction in hematoma formation per meta-analyses - Increased transfusion requirements - Possible increased infection risk - AOANJRR data shows no benefit **Arguments for drains** (minority practice): - Significant bleeding concern - Oozing after closure - Anticoagulated patient **Current recommendation**: Do NOT routinely use drains in uncomplicated primary THA ### Postoperative Management **Immediate (Day 0-1)**: - Abduction pillow between legs in bed - VTE prophylaxis: Enoxaparin 40mg SC daily starting 6-12h postop OR rivaroxaban 10mg daily starting 6-12h postop - Multimodal analgesia: paracetamol 1g QID, celecoxib 200mg BD if no contraindication, oxycodone 5-10mg Q4h PRN, local infiltration analgesia - Mobilize with physiotherapy day 1 (walker or crutches) - Weight-bearing as tolerated (modern uncemented stems support immediate full weight-bearing) **Hip precautions** (controversial): - Traditional teaching: avoid flexion greater than 90°, avoid adduction past midline, avoid internal rotation - for 6-12 weeks - Modern approach with robust posterior repair: NO hip precautions - evidence supports safety - Discuss approach with patient preoperatively **Discharge (Day 2-4)**: - When safe mobilization achieved - Pain controlled on oral medications - Home assessment completed if needed **Follow-up schedule**: - 2 weeks: wound check, remove staples - 6 weeks: X-ray (AP pelvis and lateral hip), clinical assessment - 1 year: X-ray and clinical - Then per AOANJRR protocol: 1, 3, 5, 7, 10 years minimum **Technical Tip**: EXAM KEY - Posterior soft tissue repair is CRITICAL for reducing dislocation risk from 10-15% to 2-4%. Repair must be robust: strong suture, bone tunnels in greater trochanter, tied with hip in neutral (not flexed). VTE prophylaxis is mandatory per Australian guidelines: 35 days of pharmacological prophylaxis (enoxaparin 40mg SC daily OR rivaroxaban 10mg daily) based on ACCP evidence that extended prophylaxis reduces late VTE events. Modern accelerated recovery protocols allow discharge day 2-4, return to driving 6 weeks, return to low-impact sports 3 months. ## 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. doi:10.2106/00004623-197860020-00014 - Original definition of acetabular safe zone (30-50° inclination, 10-30° anteversion) showing 4% dislocation rate inside versus 15% outside zone 2. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). *Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report*. Adelaide: AOA; 2023. - Comprehensive Australian registry data: uncemented THA 95% survivorship at 15 years, HXLPE reduces revision by 30% versus standard PE, dislocation leading cause of early revision 3. Ranawat CS, Maynard MJ. Modern techniques of cemented total hip arthroplasty. *Tech Orthop*. 1991;6(3):17-25. - Combined anteversion concept: femoral stem anteversion plus acetabular cup anteversion should total 25-50° (Ranawat safe zone) to prevent impingement and instability 4. Abdel MP, von Roth P, Jennings MT, Hanssen AD, Pagnano MW. What safe zone? The vast majority of dislocated THAs are within the Lewinnek safe zone for acetabular component position. *Clin Orthop Relat Res*. 2016;474(2):386-391. doi:10.1007/s11999-015-4432-5 - Modern study showing 58% of dislocations occur with cups in Lewinnek safe zone - emphasizes multifactorial nature of stability including spinopelvic mobility, soft tissue repair, impingement 5. Khatod M, Barber T, Paxton E, Namba R, Fithian D. An analysis of the risk of hip dislocation with a contemporary total joint registry. *Clin Orthop Relat Res*. 2006;447:19-23. doi:10.1097/01.blo.0000218752.22613.78 - Large registry study: 32mm heads reduce dislocation versus 28mm heads (1.8% versus 2.9%), larger heads provide better stability through increased jump distance 6. Callanan MC, Jarrett B, Bragdon CR, et al. The John Charnley Award: risk factors for cup malpositioning: quality improvement through a joint registry at a tertiary hospital. *Clin Orthop Relat Res*. 2011;469(2):319-329. doi:10.1007/s11999-010-1487-1 - Identifies risk factors for cup malposition including obesity, female sex, developmental dysplasia - emphasizes importance of accurate intraoperative positioning techniques 7. Kurtz SM, Gawel HA, Patel JD. History and systematic review of wear and osteolysis outcomes for first-generation highly crosslinked polyethylene. *Clin Orthop Relat Res*. 2011;469(8):2262-2277. doi:10.1007/s11999-011-1872-4 - Systematic review: HXLPE reduces wear rate from 0.1-0.2mm/year (standard PE) to less than 0.05mm/year, dramatically reduces osteolysis and aseptic loosening 8. White RE Jr, Forness TJ, Allman JK, Junick DW. Effect of posterior capsular repair on early dislocation in primary total hip replacement. *Clin Orthop Relat Res*. 2001;(393):163-167. doi:10.1097/00003086-200112000-00019 - Prospective study: posterior capsule and external rotator repair reduces dislocation from 10% to 0% in posterior approach THA - emphasizes importance of robust soft tissue repair 9. Falck-Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. *Chest*. 2012;141(2 Suppl):e278S-e325S. doi:10.1378/chest.11-2404 - ACCP guidelines: extended pharmacological VTE prophylaxis for 35 days after THA reduces late VTE events - basis for Australian guideline recommendations 10. Grammatopolous G, Pandit HG, da Assunção R, et al. Pelvic position and movement during hip replacement. *Bone Joint J*. 2014;96-B(7):876-883. doi:10.1302/0301-620X.96B7.32107 - Spinopelvic mobility affects functional cup position - patients with stiff spines have altered pelvic tilt affecting cup version during sitting/standing, contributing to instability even with cups in radiographic safe zone

Total Hip Arthroplasty - Primary (Uncemented)

Total Hip Arthroplasty - Primary (Uncemented)