Total Hip Arthroplasty Surgical Approaches

Surgical approach selection is one of the most debated topics in total hip arthroplasty. Despite decades of research, no single approach has emerged as clearly superior across all outcomes. The choice depends on surgeon experience, patient factors, and specific clinical scenarios.

The four main approaches:

1. Posterior approach (Moore, Southern, Kocher-Langenbeck modified)

   • Most commonly used worldwide and in Australia (60% AOANJRR)
   • Through or around piriformis and short external rotators
   • Historically higher dislocation rate, now comparable with soft tissue repair

2. Direct anterior approach (Smith-Petersen, Hueter)

   • Growing popularity, especially in North America
   • True internervous/intermuscular plane (femoral vs superior gluteal)
   • Lowest dislocation rates but learning curve and fracture risk

3. Anterolateral approach (Watson-Jones, modified Hardinge)

   • Split through gluteus medius and minimus
   • Good exposure of both acetabulum and femur
   • Risk to superior gluteal nerve

4. Direct lateral approach (Hardinge, transglueteal)

   • Detachment or split of abductors from greater trochanter
   • Versatile and extensile
   • Requires meticulous abductor repair

Historical context:

The evolution of THA approaches reflects changing priorities:

• 1950s-1960s: Lateral approaches dominant (Charnley)
• 1970s-1980s: Posterior approach gains popularity (easier acetabular exposure)
• 1990s-2000s: Concern over posterior dislocation drives minimally invasive/anterior interest
• 2010s-present: Posterior capsule repair equalizes dislocation rates; approach choice based on surgeon preference

Australian practice patterns (AOANJRR 2023):

• Posterior approach: 60% of primary THAs
• Lateral/transglueteal: 25%
• Anterior approaches: 15%
• Revision surgery: posterior approach preferred (70%) for better exposure

Posterior Approach Anatomy

Surface anatomy:

• Patient lateral decubitus
• Incision centered over greater trochanter, curving posteriorly
• Landmarks: PSIS, greater trochanter, femoral shaft

Layers and interval:

1. Skin and subcutaneous tissue
2. Fascia lata - incise in line with fibers
3. Gluteus maximus - split in line with fibers (proximal) or elevate inferior border
4. Short external rotators - piriformis, superior gemellus, obturator internus, inferior gemellus
5. Posterior capsule - releases with short ERs
6. Joint

Critical structures:

• Sciatic nerve: Emerges inferior to piriformis, runs posterior to obturator internus/gemelli

  • Peroneal division more lateral and superficial - most vulnerable
  • Protect with anterior retractor during femoral preparation
  • At risk with: retraction, cement extrusion, leg lengthening over 4cm

• Superior gluteal nerve and vessels: Enter gluteus medius 5cm proximal to GT

  • Safe if stay distal to piriformis
  • Risk with proximal dissection

• Inferior gluteal vessels: Posterior to femur

  • Risk with overzealous posterior retraction

Key surgical pearl: The posterior approach is not truly internervous. It splits the gluteus maximus (inferior gluteal nerve) and releases the short external rotators (nerve to quadratus femoris and individual nerve branches). The advantage is excellent exposure, not preservation of innervation.

Direct Anterior Approach Anatomy

Surface anatomy:

• Patient supine on standard or fracture table
• Incision 2-3cm lateral and distal to ASIS
• Extends distally toward lateral patella

True internervous interval (Smith-Petersen):

• Lateral: Tensor fascia lata (superior gluteal nerve)
• Medial: Sartorius and rectus femoris (femoral nerve)

Layers:

1. Skin and subcutaneous tissue
2. Fascia lata - incise between TFL and sartorius
3. Internervous plane - develop bluntly
4. Reflected head of rectus femoris - release from capsule
5. Anterior capsule - T-shaped or cruciate release
6. Joint

Critical structures:

• Lateral femoral cutaneous nerve (LFCN)

  • Runs just lateral to incision or through operative field
  • Injury rate 5-20%, usually temporary paresthesia
  • Cannot always be avoided but identify if visible

• Femoral nerve and vessels

  • Medial to surgical field (under sartorius/rectus)
  • Protected by staying lateral
  • Risk with medial retractor placement

• Ascending branch LFCA

  • Crosses surgical field on anterior capsule
  • Ligate or cauterize - can bleed significantly

Lateral Approach Anatomy (Hardinge/Transglueteal)

Surface anatomy:

• Lateral decubitus or supine
• Incision centered over greater trochanter
• Extends proximally and distally

Layers:

1. Skin and subcutaneous tissue
2. Fascia lata and IT band - incise longitudinally
3. Gluteus medius and minimus - split anterior third or detach from GT
4. Capsule - T-shaped release
5. Joint

Critical structure - Superior gluteal nerve:

• Enters gluteus medius 5cm proximal to tip of GT
• Runs between medius and minimus
• Injured by:
  • Splitting medius more than 5cm proximal to GT
  • Splitting posterior to anterior third of muscle
  • Excessive retraction

Abductor repair: The detached anterior third of medius/minimus must be repaired back to greater trochanter with non-absorbable sutures through bone. Failure of repair or healing leads to abductor deficiency.

Anterolateral Approach (Watson-Jones)

Similar to lateral approach but:

• More anterior incision (ASIS toward GT)
• Works anterior to gluteus medius (elevates off femur anteriorly)
• Less abductor damage but still risks superior gluteal nerve
• Capsule release more challenging

Posterior Approach: NOT truly internervous - splits gluteus maximus (inferior gluteal nerve) and releases short external rotators. The advantage is excellent exposure, not nerve preservation.

Direct Anterior (Smith-Petersen/Hueter): TRUE internervous interval between TFL (superior gluteal) and sartorius/rectus femoris (femoral nerve). No muscle cutting required.

Lateral (Hardinge): NOT internervous - splits or detaches gluteus medius/minimus. Superior gluteal nerve at risk if split extends greater than 5cm proximal to GT.

Anterolateral (Watson-Jones): Develops interval between TFL and gluteus medius. Both supplied by superior gluteal nerve but can be safely separated.

Preoperative Patient Evaluation

Patient factors influencing approach choice:

1. Body habitus

   • BMI over 35: consider posterior (anterior difficult with large pannus)
   • Body fat distribution affects exposure

2. Prior surgery

   • Previous hip surgery scar location
   • Prior approach may influence current choice
   • Scar tissue considerations

3. Comorbidities

   • Parkinson's disease: consider anterior (lower dislocation risk)
   • Spinal fusion: assess spinopelvic mobility
   • Neuromuscular disease: dislocation risk assessment

4. Activity level and goals

   • High-demand patients: approach with lowest complication risk
   • Return to sport considerations

5. Hip pathology

   • DDH: posterior preferred (better acetabular exposure)
   • Protrusio: posterior or lateral
   • Revision cases: extensile approach needed

Clinical examination:

• Hip range of motion limitations
• Leg length discrepancy
• Spinopelvic mobility assessment
• Prior incision locations

The clinical assessment guides appropriate approach selection based on individual patient factors.

Preoperative Imaging

Standard imaging:

• AP pelvis X-ray: Assess hip anatomy, template implants, measure leg lengths
• Lateral hip X-ray: Assess version, anterior/posterior offset
• Full-length standing X-rays: If leg length discrepancy or spinopelvic concerns

Advanced imaging for specific scenarios:

• CT scan with 3D reconstruction: DDH, revision cases, complex acetabular anatomy
• Spinopelvic films (standing and sitting lateral): If stiff spine or flat back syndrome concerns
• MRI: Not routine for approach planning, used for soft tissue pathology assessment

Templating:

• Essential for all approaches
• Determines component sizes
• Assesses offset and leg length restoration needs
• Digital templating increasingly used

Special considerations:

• Anterior approach may use fluoroscopy intraoperatively
• Complex cases benefit from detailed preoperative imaging review

Appropriate imaging helps surgical planning and approach selection based on individual anatomy.

Sciatic Nerve Injury (Posterior Approach)

Anatomy:

• Emerges from sciatic notch below piriformis
• Composed of tibial and peroneal divisions
• Peroneal division lateral, superficial, tethered → most vulnerable
• Average 1.2cm from posterior capsule

Mechanisms of injury:

1. Direct trauma - retractor placement, sharp dissection
2. Traction - leg lengthening over 4cm, retractor pressure
3. Compression - cement extrusion, hematoma
4. Thermal - cement polymerization (rare with modern techniques)

Prevention strategies:

• Place anterior (ilioischial) retractor to protect nerve during femoral preparation
• Limit leg lengthening to under 4cm (higher risk over 4cm)
• Gentle retraction, release periodically
• Prevent posterior cement extrusion
• Consider nerve monitoring in revision or complex cases (controversial)

Clinical presentation:

• Peroneal division most commonly affected (foot drop, numbness)
• May be immediate or delayed (hematoma, swelling)
• Check postoperatively before leaving OR

Management:

• Immediate: Explore if complete palsy noted immediately (rule out impingement)
• Delayed: Observe, nerve studies at 3-4 weeks, AFO for foot drop
• Most improve over 6-12 months
• Incomplete recovery common (60-70% partial/complete recovery)

Lateral Femoral Cutaneous Nerve (Anterior Approach)

Anatomy:

• Variable course, usually lateral to ASIS
• Provides sensation to anterolateral thigh
• May cross or run through surgical field

Injury rate:

• 5-20% in most series
• Usually temporary (neuropraxia)
• Most recover over 6-12 months
• Rarely permanent functional issue

Prevention:

• Identify nerve if visible and protect
• Cannot always prevent (variant anatomy)
• Warn patient preoperatively about numbness risk

Management:

• Reassurance - usually improves
• Rarely requires treatment
• Symptoms diminish even if nerve divided

Superior Gluteal Nerve (Lateral Approaches)

Anatomy:

• Exits pelvis through sciatic notch above piriformis
• Runs between gluteus medius and minimus
• Enters gluteus medius 5cm proximal to GT
• Supplies gluteus medius, minimus, TFL

Mechanisms of injury:

1. Proximal dissection beyond 5cm above GT
2. Splitting gluteus medius posterior to anterior third
3. Excessive retraction

Prevention:

• 5cm rule: Do not dissect more than 5cm proximal to GT tip
• Anterior third rule: Split only anterior one-third of medius
• Gentle retraction

Clinical presentation:

• Trendelenburg gait (drops contralateral pelvis with single leg stance)
• Abductor weakness
• May be masked initially by pain/guarding

Management:

• If suspected, abductor strengthening
• Gait training
• Usually does not recover (motor nerve)
• May require revision to trochanteric advancement

Dislocation by Approach (Modern Data)

Direct Anterior Approach:

• Lowest dislocation rate: 0.6-1%
• Direction: Anterior dislocation (extension/external rotation)
• Rare enough that some surgeons give no formal precautions
• AOANJRR confirms lower dislocation risk

Posterior Approach (with repair):

• 2-3% dislocation rate
• Historical rate 5% without repair
• Posterior soft tissue repair reduces risk by 50-60%
• Direction: Posterior (flexion/adduction/internal rotation)

Lateral Approaches:

• 1-2% dislocation rate
• Direction: Variable (usually anterolateral)
• Less specific precautions needed

Posterior Soft Tissue Repair Techniques

Key structures to repair:

1. Short external rotators (piriformis, gemelli, obturator internus)
2. Posterior capsule
3. Consider quadratus femoris if released

Repair methods:

1. Tag and repair to GT/posterior femur

   • Tag short ERs before release with heavy suture
   • After implants, repair to GT via drill holes or suture anchors
   • Strong, anatomic

2. Capsular repair

   • Side-to-side capsule repair
   • May use figure-of-8 technique
   • Good for thin tissue

3. Piriformis advancement

   • Advance piriformis distally for tension
   • Can combine with capsule repair

Evidence for repair:

• Multiple studies show 50-60% reduction in dislocation
• No increase in operative time (5-10 minutes)
• Minimal additional morbidity
• Should be standard practice

Patient Precautions by Approach

Risk Factors for Dislocation (All Approaches)

Patient factors:

• Prior hip surgery (2-3x risk)
• Neuromuscular disease (cerebral palsy, Parkinson's)
• Cognitive impairment (non-compliance)
• Alcohol abuse
• Younger age (higher activity)

Surgical factors:

• Inadequate soft tissue repair
• Component malposition (especially combined anteversion issues)
• Small femoral head (22mm vs 32mm or larger)
• Soft tissue tension (offset restoration)

Management of recurrent dislocation:

1. Assess component position (CT if needed)
2. Consider closed reduction and bracing
3. Revision if malposition
4. Dual mobility bearing
5. Constrained liner (last resort)

Minimally Invasive Surgery (MIS) Concepts

Definition:

• Smaller incision (under 10cm)
• Muscle-sparing techniques
• Often requires specialized instruments/retractors

Approaches adaptable to MIS:

• MIS posterior: Single or two-incision
• MIS anterior: Direct anterior is inherently muscle-sparing
• MIS lateral: Mini-incision transglueteal

Theoretical advantages:

• Less tissue trauma
• Faster recovery
• Reduced blood loss
• Improved cosmesis
• Earlier return to function

Challenges and risks:

• Learning curve steeper than standard approaches
• Component malposition risk if visualization limited
• Femoral fracture risk (especially anterior)
• May need to extend incision (should have low threshold)
• Limited benefit in obese patients (adipose, not muscle, creates depth)

Evidence:

• Early enthusiasm has been tempered
• Meta-analyses show minimal clinical benefit over well-performed standard approaches
• Complication rates higher during learning curve
• Long-term outcomes (component position, survival) similar
• Cosmetic benefit real but functional benefit questionable

Muscle-Sparing Modifications

Posterior modifications:

• Preserve piriformis: Work below piriformis, release only inferior rotators
• Minimize gluteus maximus split: Use inferior border elevation instead
• Claims of less Trendelenburg, unproven benefit

Anterior modifications:

• Standard DAA is already muscle-sparing (internervous)
• Focus on learning curve reduction, fracture prevention

Lateral modifications:

• Superior capsulotomy without abductor detachment
• Requires specialized retractors
• May reduce abductor dysfunction

Two-Incision MIS (Historical)

Concept:

• Anterior incision for acetabulum
• Posterior incision for femur
• Proposed in 2000s

Abandoned due to:

• High complication rate
• Femoral component malposition
• No clear benefit
• Steep learning curve

Lesson learned: Visualization and precision trump incision size.

Direct Superior Approach (SuperPATH, Others)

Concept:

• Superior capsulotomy preserving anterior and posterior capsule
• In situ neck cut
• Femoral and acetabular work through superior window

Theoretical advantages:

• Preserve capsule (low dislocation)
• Muscle-sparing

Challenges:

• Limited visualization
• Component position concerns
• Requires specific instruments
• Long-term data limited

Current status:

• Growing use in Asia and some US centers
• Remains controversial
• Requires specialized training

Matching Approach to Patient

Approach-Specific Complications Detail

Posterior Approach:

1. Sciatic nerve palsy (0.5-1%)

   • Most serious complication
   • Peroneal division typically affected
   • Prevention: anterior retractor, limit lengthening, gentle retraction
   • Partial recovery in 60-70%

2. Dislocation (2-3% with repair, 5% without)

   • Historically biggest concern
   • Transformed by soft tissue repair
   • Risk factors: prior surgery, neuromuscular disease, obesity
   • Prevention: meticulous repair, component position, large head

3. Gluteus maximus damage

   • Rare but causes Trendelenburg if severe
   • Avoid excessive splitting
   • Usually minor functional issue

Direct Anterior Approach:

1. LFCN injury (5-20%)

   • Most common complication
   • Usually temporary paresthesia
   • Most improve over 6-12 months
   • Rarely significant functional problem
   • Warn patients preoperatively

2. Intraoperative fracture (2-3%)

   • Greater trochanter, femoral shaft
   • Higher during learning curve
   • Related to forceful broaching, poor exposure
   • Prevention: adequate hyperextension, gentle technique, low threshold to extend incision
   • Recognize intraoperatively and fix (cables, cerclage, plate)

3. Femoral nerve injury (under 1%)

   • Rare but devastating
   • Related to medial retractor malposition
   • Prevention: ensure retractors on bone, avoid soft tissue compression
   • If occurs, explore and decompress

4. Wound complications

   • Hematoma formation (lower position, gravity)
   • May be higher in obese patients
   • Good hemostasis critical

Lateral Approaches:

1. Superior gluteal nerve injury (1-2%)

   • Causes abductor denervation
   • Trendelenburg gait
   • Prevention: 5cm rule, anterior third only
   • Usually permanent

2. Abductor repair failure (5-10%)

   • Presents as Trendelenburg, abductor weakness
   • Prevention: non-absorbable suture, bone attachment, patient compliance with precautions
   • May require revision to trochanteric advancement or abductor reconstruction

3. Heterotopic ossification

   • May be higher than posterior (more muscle trauma)
   • Consider prophylaxis in high-risk patients

Common to All Approaches:

1. Infection (1-2%)

   • Similar rates across approaches
   • Antibiotic prophylaxis, sterile technique
   • Higher risk: obesity, diabetes, immunosuppression

2. DVT/PE

   • Chemoprophylaxis per guidelines
   • Early mobilization
   • Approach does not significantly affect risk

3. Leg length discrepancy

   • Related to technique, not approach
   • Templating and intraoperative assessment

4. Component malposition

   • Can occur with any approach
   • Higher during learning curve
   • Navigation may help but not proven superior

General Postoperative Protocol

Immediate postoperative (Day 0-1):

• Pain management (multimodal analgesia)
• DVT prophylaxis (LMWH or oral anticoagulant per guidelines)
• Drain management if used (remove at 24 hours)
• Mobilization same day or day 1 with physiotherapy
• Weight-bearing as tolerated (all approaches)

Early recovery (Days 1-7):

• Progressive mobilization with walking aids
• Gait training specific to approach precautions
• Wound monitoring
• Hospital discharge typically day 2-4

Approach-specific precautions (6-12 weeks):

• Posterior approach: Avoid flexion over 90 degrees, adduction, internal rotation
• Anterior approach: Minimal or no precautions (some surgeons), avoid extension/ER combinations if precautions given
• Lateral approach: Avoid active abduction against resistance (protect repair), otherwise unrestricted

Weeks 6-12:

• Progressive strengthening
• Weaning from walking aids
• Return to desk work typically 6 weeks
• Return to manual work 12 weeks
• Return to sports 3-6 months depending on activity

Long-term:

• No permanent activity restrictions
• Regular follow-up (6 weeks, 12 weeks, 6 months, then annually)
• Registry participation (AOANJRR)

The postoperative care protocol is similar across approaches with variations in specific precautions.

AOANJRR 2023 Report - Approach Data

Primary THA approach distribution:

• Posterior approach: 60% (most common)
• Lateral/transglueteal: 25%
• Anterior approaches: 15% (growing)

Revision THA approach distribution:

• Posterior approach: 70% (preferred for exposure)
• Lateral: 20%
• Anterior: 10% (limited use in revision)

Revision Rates by Approach

Key finding: No significant difference in revision rates

When analyzed by surgeon experience (greater than 30 cases/year of specific approach), revision rates at 10 years:

• Posterior: 7.2%
• Lateral: 7.5%
• Anterior: 7.0%

Differences are not statistically significant.

Reasons for revision by approach:

Key observations:

• Anterior has lowest dislocation revision rate (consistent with literature)
• Anterior has slightly higher fracture revision rate (intraoperative fractures)
• Aseptic loosening similar across all approaches (technique-dependent, not approach)

Surgeon Volume Effect

Critical finding: Surgeon experience matters more than approach

Revision rates by surgeon volume:

• Low volume (under 15 cases/year): 10.2% at 10 years
• Medium volume (15-30 cases/year): 8.1%
• High volume (over 30 cases/year): 6.8%

Implication: A surgeon performing 50 posterior approaches per year will have better outcomes than a surgeon performing 10 anterior approaches per year. Master one approach rather than dabbling in multiple.

Learning Curve Data

Complications during learning:

Anterior approach learning curve:

• First 20 cases: Higher fracture, nerve injury, malposition
• Cases 20-50: Improving but not yet optimal
• After 50 cases: Comparable to experienced posterior surgeons
• Recommend mentorship and training courses

International Comparisons

United States:

• Posterior: 50-55%
• Anterior: 30-35% (higher than Australia, marketing influence)
• Lateral: 15-20%

United Kingdom (NJR):

• Posterior: 70-75% (higher than Australia)
• Lateral: 20-25%
• Anterior: under 5% (lower adoption than Australia)

Scandinavia (Nordic Registries):

• Posterior: 55-60%
• Lateral: 35-40% (Hardinge tradition from Charnley era)
• Anterior: 5-10%

Trends:

• Anterior approach growing worldwide but slower in UK/Australia than US
• Posterior remains most common globally
• Lateral declining slightly

AOANJRR Data (2023 Annual Report)

Primary THA approach distribution in Australia:

• Posterior approach: 60% (most common)
• Lateral/transglueteal approaches: 25%
• Anterior approaches (direct anterior, anterolateral): 15%

Revision THA approach distribution:

• Posterior approach: 70% (preferred for exposure)
• Lateral approaches: 20%
• Anterior approaches: 10%

Trends over time:

• Posterior approach: stable at 55-60% over past decade
• Anterior approaches: gradual increase from under 5% in 2010 to 15% in 2023
• Lateral approaches: gradual decrease from 35% to 25%

Key registry findings:

1. Revision rates similar across approaches when controlled for surgeon volume

   • 10-year revision rate: 7.0-7.5% for all approaches
   • No statistically significant difference

2. Surgeon volume effect is pronounced

   • Low volume (under 15 cases/year): 10.2% revision at 10 years
   • High volume (over 30 cases/year): 6.8% revision at 10 years
   • Volume matters more than approach

3. Reasons for revision differ by approach

   • Dislocation revision: highest for posterior (18%), lowest for anterior (8%)
   • Fracture revision: slightly higher for anterior (15% vs 10-12%)
   • Infection and loosening: similar across approaches

4. Patient selection varies by approach

   • Anterior approach: younger average age (62 vs 68 years)
   • Lateral approach: more DDH and complex acetabular cases
   • Posterior approach: widest range of indications

Training and Practice Patterns

Orthopaedic examination expectations:

• Must be competent in at least one approach
• Should understand indications, contraindications, and complications of all major approaches
• Expected to know AOANJRR data on approach usage and outcomes
• Should be able to discuss approach selection for different clinical scenarios

Australian training:

• Most trainees learn posterior approach as primary approach
• Increasing exposure to anterior approach in major centers
• Lateral approach less commonly taught now (decreasing use)
• Emphasis on posterior soft tissue repair techniques

Public vs Private Practice

Private practice:

• Anterior approach more common (15-20% of cases)
• Marketing influence ("muscle-sparing," "rapid recovery")
• Patient-driven requests for specific approaches

Public practice:

• Posterior approach dominant (70-75%)
• Focus on approach surgeons know best
• Less marketing influence

Specialty Centers

Major arthroplasty centers (Perth, Sydney, Melbourne) often have:

• Surgeons subspecializing in specific approaches
• High-volume anterior approach surgeons
• Navigation and robotic systems
• Research participation

Regional centers:

• Primarily posterior approach
• Standard techniques
• Focus on reliability and surgeon familiarity

Professional Society Positions

Australian Orthopaedic Association:

• No formal recommendation for specific approach
• Emphasizes surgeon training and proficiency
• Supports AOANJRR data sharing
• Encourages evidence-based practice

Hip Society of Australia:

• Educational courses on all approaches
• Anterior approach workshops available
• Emphasis on surgical fundamentals over marketing

Patient Information Resources

Arthritis Australia and Australian Orthopaedic Association provide patient education:

• Information on different approaches available
• Emphasis that surgeon experience matters most
• Advice to discuss approach options with surgeon
• Realistic expectations for recovery timelines