Hip Direct Lateral Approach (Hardinge)
Comprehensive guide to the Hardinge direct lateral approach to the hip - indications, technique, internervous plane, structures at risk, and surgical pearls for Orthopaedic exam
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HARDINGE DIRECT LATERAL APPROACH TO HIP
Transgluteal | Superior Gluteal Nerve at Risk | Most Common THA Approach in Australia
Critical Hardinge Approach Exam Points
No True Internervous Plane
Both TFL and gluteus medius are supplied by the superior gluteal nerve. This is not a true internervous plane - muscle splitting is required. Minimize denervation by splitting at musculotendinous junction.
Superior Gluteal Nerve Danger Zone
The superior gluteal nerve exits the pelvis 5cm proximal to the greater trochanter. Dissection beyond this risks permanent abductor paralysis. Always measure from GT before proximal extension.
Abductor Mechanism Repair
Meticulous repair of gluteus medius back to trochanter is critical. Poor repair causes Trendelenburg gait. Use non-absorbable suture through bone tunnels or repair to vastus ridge.
Dislocation Risk Profile
Lower dislocation risk (3%) compared to posterior approach (5-7%) but higher abductor weakness. Stability is excellent but gait may be compromised if poor repair or nerve injury.
Quick Decision Guide - Approach Selection
HARDINGEHARDINGE - Key Steps
Memory Hook:HARDINGE guides you through the direct lateral approach - remember the nerve danger zone!
SGASGA RISK - Superior Gluteal Artery
Memory Hook:SGA exits 5cm proximal to GT - stay distal to avoid disaster
REPAIRREPAIR - Gluteus Medius Closure
Memory Hook:A good REPAIR prevents Trendelenburg gait - the most important step in Hardinge closure!
Overview and Background
Historical Background:
The direct lateral approach to the hip was originally described by McFarland and Osborne in 1954, and later modified by Hardinge in 1982. Hardinge's modification specifically addressed the anterior portion of gluteus medius, splitting it at the musculotendinous junction to minimize denervation while providing excellent exposure.
Evolution of the approach:
- 1954: McFarland and Osborne describe transgluteal approach
- 1982: Hardinge publishes seminal modification with GM split technique
- 1990s-2000s: Becomes dominant approach in Australia and UK
- 2010s: DAA gains popularity but direct lateral remains common
Current status: The Hardinge direct lateral approach is the most commonly used THA approach in Australia (approximately 40% of primary THA per AOANJRR). It offers excellent stability with lower dislocation rates than posterior approach, though at the cost of potential abductor mechanism disruption.
Why this approach matters:
- Most common approach nationally - essential for Orthopaedic exam
- Lower dislocation rate than posterior approach
- Good femoral and acetabular exposure
- Familiar to most Australian orthopaedic surgeons
- Requires understanding of abductor protection and repair
Indications and Contraindications
Indications
Primary indications:
- Primary total hip arthroplasty
- Hemiarthroplasty (femoral neck fractures)
- Hip resurfacing arthroplasty
- Simple revision THA (liner exchange, head/neck change)
Advantages:
- Lower dislocation rate compared to posterior approach
- Excellent femoral exposure for stem insertion
- Familiar to most Australian surgeons
- Good acetabular visualization (anterior and superior)
- No posterior soft tissue disruption
Disadvantages:
- Splits abductor mechanism (risk of weakness)
- Superior gluteal nerve at risk with proximal extension
- Limited posterior acetabular wall access
- Higher abductor weakness compared to anterior approach
AOANJRR Data
The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) reports that direct lateral approach accounts for approximately 40% of primary THA in Australia, making it the most common approach nationally.
Key Anatomy
Muscular layers (superficial to deep):
- Tensor fascia lata (TFL) - anterior muscle of iliotibial band
- Gluteus medius (GM) - main hip abductor
- Gluteus minimus - deep hip abductor
- Hip joint capsule
Neurovascular structures:
- Superior gluteal nerve (L4-S1): Exits pelvis above piriformis, 5cm proximal to greater trochanter
- Superior gluteal artery: Accompanies nerve, bleeding if violated
- Inferior gluteal nerve and vessels: Posteriorly (safe)
- Femoral neurovascular bundle: Anteriorly (safe)
Superior Gluteal Nerve Protection
The superior gluteal nerve exits the greater sciatic notch approximately 5cm proximal to the tip of the greater trochanter. It innervates gluteus medius, gluteus minimus, and TFL. Injury causes irreversible Trendelenburg gait. Measure this distance intraoperatively and avoid dissection beyond 4cm proximal to GT.
Trochanteric anatomy:
- Greater trochanter: Insertion of gluteus medius (superior facet), gluteus minimus (anterior facet)
- Vastus ridge: Lateral femur - origin of vastus lateralis
- Piriformis fossa: Medial GT - landmark for femoral canal
Anatomy and Biomechanics
Neuromuscular anatomy:
The key to understanding the Hardinge approach is appreciating that there is no true internervous plane. Both muscles in the interval (TFL and gluteus medius) are supplied by the superior gluteal nerve, making this a muscle-splitting rather than muscle-separating approach.
Superior gluteal nerve course:
- Exits pelvis through greater sciatic notch above piriformis
- Passes between gluteus medius and minimus
- Enters muscles approximately 5cm proximal to GT tip
- Supplies: Gluteus medius, gluteus minimus, tensor fasciae latae
- Injury causes permanent abductor paralysis
Biomechanical considerations:
Abductor mechanism:
- Gluteus medius is the primary hip abductor
- Moment arm: Distance from hip center to GT
- Required for pelvic stability during single-leg stance
- Splitting the muscle temporarily weakens abduction
- Meticulous repair essential for functional recovery
Muscle fiber architecture:
- GM: Fan-shaped, multiple pennation angles
- Anterior fibers: Internal rotation, flexion
- Middle fibers: Pure abduction
- Posterior fibers: External rotation, extension
- Splitting anterior portion preserves majority of function
Internervous Plane
No True Internervous Plane
The Direct Lateral (Hardinge) approach involves splitting muscles that are supplied by the same nerve.
- Interval: Between Tensor Fascia Lata (TFL) and Gluteus Medius.
- Nerve Supply: Superior Gluteal Nerve supplies BOTH muscles.
- Technique: The approach involves splitting the TFL and the anterior one-third of the Gluteus Medius.
- Safety: To minimize denervation, the split in the Gluteus Medius should not extend more than 5 cm proximal to the greater trochanter (nerve entry point).
This is distinguishing feature from the Anterior (Smith-Petersen) which has a TRUE internervous plane.
Classification Systems
Direct Lateral Approach Variants
Original McFarland-Osborne (1954):
- Full transgluteal split
- Higher denervation risk
- Largely abandoned
Hardinge Modification (1982):
- Splits anterior half of GM at musculotendinous junction
- Current standard
- Minimizes denervation
Dall Modification:
- Detaches anterior GM insertion completely
- Easier repair via bone tunnels
- Some prefer for revision cases
The Hardinge modification is the standard technique described here.
Clinical Assessment
Preoperative Assessment:
History:
- Nature and duration of hip pathology
- Previous surgery (affects approach choice)
- Functional status and expectations
- Medical comorbidities affecting surgery
Physical Examination:
- Gait assessment (baseline Trendelenburg)
- Range of motion (flexion, rotation, abduction)
- Leg length assessment
- Neurovascular status documentation
- Abductor strength (baseline for comparison)
Specific assessment for Hardinge approach:
- Abductor strength testing: Pre-existing weakness may worsen
- Obesity assessment: BMI over 35 increases technical difficulty
- Skin condition: Lateral incision site evaluation
- Hip ROM: Extension needed for femoral preparation
Preoperative Documentation
Document baseline abductor function before surgery. If patient has pre-existing Trendelenburg from previous surgery or pathology, this must be noted. Post-operative weakness will be blamed on surgery if not documented preoperatively.
Investigations
Imaging:
Essential:
- AP pelvis radiograph: Both hips for comparison, templating
- Lateral hip: Femoral version, anterior osteophytes
- Cross-table lateral: If patient cannot flex hip
Templating requirements:
- Acetabular cup size and position
- Femoral stem sizing and offset
- Leg length correction planning
- Identifies challenging anatomy (protrusio, DDH)
Advanced imaging (selective):
- CT: Complex anatomy, revision surgery, bone stock assessment
- MRI: Soft tissue assessment, AVN staging, infection workup
- Bone scan: Infection or loosening workup
Laboratory:
- FBC, UEC, coagulation studies
- Group and hold (cross-match if revision)
- CRP/ESR if infection concern
- HbA1c for diabetics
Management Algorithm
Approach Selection Algorithm
Step 1: Is patient suitable for ANY THA?
- Failed conservative management
- Adequate bone stock for implants
- Medical fitness for surgery
Step 2: Hardinge approach considerations
Ideal candidates:
- Primary THA with standard anatomy
- Femoral neck fracture (hemiarthroplasty)
- Low dislocation risk priority
- Surgeon comfortable with approach
Consider alternatives if:
- Previous lateral surgery with abductor damage
- Need for extensive posterior acetabular access
- Severe DDH requiring proximal exposure
- Patient preference after informed consent
Surgeon experience is the most important factor in approach selection.
Positioning
Setup Checklist
Lateral decubitus position on radiolucent table with affected hip up.
- Pelvis perpendicular to floor (check with C-arm AP view)
- Anterior supports: Pubis and sacrum
- Posterior support: Against sacrum
- Perineal post: If using traction table (not mandatory)
- Down leg: Pillow between knees, pad fibular head (peroneal nerve)
- Up leg: Free to move through range of motion
- Axilla: Protect brachial plexus with arm support
- All bony prominences: Gel pads
- Limb free-draped from iliac crest to mid-calf
- Hip can be extended, flexed, adducted, rotated freely
- C-arm access: Confirm adequate AP and lateral imaging
- Incision landmarks visible: ASIS, GT, femoral shaft
- Retractors: Hohmann, Charnley, bent Hohmann
- Oscillating saw: For femoral neck cut
- Implants: Confirm size range available
- Trial components: Full range of head sizes, neck lengths
Pelvic Orientation Critical
The pelvis must be perpendicular to the floor. Pelvic tilt or rotation causes acetabular malposition (anteversion/retroversion errors). Use C-arm to confirm true AP pelvis before starting. The obturator foramen should be symmetric and the coccyx should align with pubic symphysis.
Surgical Technique - Step by Step
Skin Incision and Superficial Dissection
Landmarks:
- Greater trochanter (GT) - palpable landmark
- Incision centered over GT
- Direction: Straight lateral, parallel to femoral shaft
Incision:
- Length: 10-15cm (8cm minimum for primary THA)
- Proximal extent: 5cm proximal to tip of GT
- Distal extent: 5cm distal to GT along femoral shaft
- Depth: Through skin and subcutaneous fat to fascia lata
Superficial dissection:
- Identify fascia lata (iliotibial band)
- Palpate greater trochanter deep to fascia
- Hemostasis of subcutaneous layer before proceeding
Incision Placement
The incision must be centered over the greater trochanter. Too anterior risks the femoral neurovascular bundle, too posterior makes anterior capsule difficult to reach. Palpate the GT carefully before marking incision.
Structures at Risk
Superior Gluteal Nerve
The Superior Gluteal Nerve is the primary structure at risk. It exits the greater sciatic notch and runs between gluteus medius and minimus, entering the muscles approximately 4-5 cm proximal to the greater trochanter. Injury results in abductor paralysis and Trendelenburg gait. Safe Zone: Dissection must remain distal to this 5cm danger zone.
Structures at Risk Summary
Complications
Complications Specific to Hardinge Approach
Abductor dysfunction:
- Incidence: 5-20% (varies by series)
- Causes: Superior gluteal nerve injury, poor GM repair, excessive splitting
- Prevention: Limit proximal dissection, meticulous repair
- Treatment: Physiotherapy, if persistent consider revision repair or GT advancement
Heterotopic ossification:
- Incidence: 10-30% (radiographic), 5% symptomatic
- Risk factors: Male, DISH, previous HO, delay to surgery
- Prevention: Indomethacin 25mg TDS for 6 weeks or single-dose radiation
- Treatment: Excision if symptomatic after maturation (12 months)
Dislocation:
- Incidence: 2-3% (lower than posterior approach)
- Direction: Usually posterior (if occurs)
- Prevention: Restore offset, avoid combined flexion-adduction-internal rotation
- Treatment: Closed reduction, if recurrent consider revision
Abductor Strength Recovery
Even with perfect technique, patients typically have temporary abductor weakness for 3-6 months post-operatively. Trendelenburg gait is common early. Reassure patients this improves with physiotherapy. Persistent weakness beyond 6 months warrants investigation (EMG to assess nerve, MRI to assess repair integrity).
Postoperative Care
Immediate Postoperative Period (Day 0-2):
Pain Management:
- Multimodal analgesia (paracetamol + NSAID + opioid PRN)
- Regional block consideration (fascia iliaca or femoral)
- PCA for first 24-48 hours if needed
- Transition to oral by day 1-2
Mobilization:
- Weight bearing as tolerated from day 0
- Walking frame initially, progress to crutches/stick
- Physiotherapy assessment for safe mobility
- Stairs before discharge
DVT Prophylaxis:
- Mechanical: TED stockings, calf pumps
- Chemical: Rivaroxaban 10mg daily for 5 weeks OR enoxaparin OR aspirin
- Early mobilization most important
Hip Precautions:
- Controversial for direct lateral approach
- Some surgeons: No precautions needed
- Conservative: Avoid extremes of motion for 6 weeks
- Most important: Avoid combined flexion-adduction-IR
Wound Care:
- Waterproof dressing until healed (10-14 days)
- Remove staples/sutures at 10-14 days
- Monitor for wound complications
- Lateral wound position: Less contamination risk than posterior
Discharge:
- Typically day 1-3 for primary THA
- Criteria: Safe mobility, wound satisfactory, pain controlled
- Arrange outpatient physiotherapy
- Emergency contact information provided
Rehabilitation:
Weeks 1-6:
- Continue walking aids (frame → crutches → stick)
- Abductor strengthening - critical for this approach
- Range of motion exercises (within precautions)
- Monitor for Trendelenburg development
Weeks 6-12:
- Wean walking aids
- Progress strengthening program
- Return to driving (typically 6-8 weeks)
- Swimming, stationary cycling permitted
Beyond 3 months:
- Return to full activities as comfort allows
- Low-impact sports acceptable
- Annual review initially, then as needed
- Lifelong follow-up recommended
Abductor Recovery Timeline
Abductor weakness is EXPECTED after Hardinge approach. Most patients have some Trendelenburg for 3-6 months. Reassure patients this improves. Persistent weakness beyond 6 months requires investigation (MRI for repair, EMG for nerve).
Outcomes and Prognosis
Functional Outcomes:
Short-term (under 2 years):
- Pain relief: Over 95% significant improvement
- Function: Harris Hip Score typically improves from 45 to over 85
- Patient satisfaction: Over 90% satisfied or very satisfied
- Return to activities: 3-6 months for most
Long-term (over 10 years):
- Implant survival: Over 95% at 10 years (similar to other approaches)
- Revision rate: Approximately 1% per year
- Dislocation rate: 2-3% (lower than posterior approach)
- Functional maintenance: Most maintain excellent function
Approach-Specific Outcomes:
Abductor function:
- Temporary weakness (under 6 months): 50-70% of patients
- Persistent weakness (over 6 months): 5-20%
- Permanent Trendelenburg: 3-5%
- Directly related to repair quality and nerve protection
Dislocation comparison:
| Approach | Dislocation Rate |
|---|---|
| Direct Lateral | 2-3% |
| Posterior | 5-7% |
| Anterior | 1-2% |
Heterotopic ossification:
- Any grade: 10-30%
- Clinically significant: 5%
- Higher than posterior approach
- Prophylaxis reduces significantly
Prognostic Factors:
Good prognosis:
- Primary THA for osteoarthritis
- Experienced surgeon
- Meticulous GM repair technique
- Good preoperative abductor function
- Compliant with rehabilitation
Poorer prognosis:
- Revision surgery
- Pre-existing abductor weakness
- Obesity (BMI over 35)
- Poor repair quality
- Superior gluteal nerve injury
Registry Data: Per AOANJRR, the direct lateral approach has revision rates equivalent to other approaches at 10 years. Surgeon volume and experience are more important predictors of outcome than approach selection.
Evidence Base and Key Studies
AOANJRR Annual Report - Approach Utilization
Abductor Function After Direct Lateral Approach
Dislocation Rates: Lateral vs Posterior Approach
Gait Analysis After Direct Lateral Approach THA
Nerve Injury Risk in Direct Lateral Approach
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Describe the Hardinge Approach
"Walk me through the Hardinge direct lateral approach to the hip. What are the key anatomical landmarks and structures at risk?"
Scenario 2: Post-op Trendelenburg Gait
"A 68-year-old woman is 6 months post THA via Hardinge approach. She has persistent Trendelenburg gait and hip abductor weakness. How would you assess and manage this?"
Scenario 3: Intraoperative Superior Gluteal Artery Bleeding
"During a Hardinge approach THA, you extend the gluteus medius split proximally to improve acetabular exposure. You encounter significant arterial bleeding from the proximal wound. How do you manage this?"
MCQ Practice Points
Internervous Plane Question
Q: What is the internervous plane in the Hardinge direct lateral approach to the hip? A: There is NO true internervous plane. Both tensor fascia lata and gluteus medius are supplied by the superior gluteal nerve. The approach splits both muscles (TFL anteriorly, GM at musculotendinous junction) to minimize denervation.
Superior Gluteal Nerve Question
Q: At what distance from the greater trochanter does the superior gluteal nerve exit the pelvis? A: Approximately 5cm proximal to the tip of the greater trochanter. Dissection beyond this point risks permanent abductor paralysis. Limit proximal extension to 4cm from GT to maintain safe zone.
Gluteus Medius Split Question
Q: Where is the gluteus medius split in the Hardinge approach? A: The anterior half of gluteus medius is split at the musculotendinous junction. This is approximately anterior third of the muscle. Splitting at the junction minimizes denervation compared to splitting through muscle belly.
Dislocation Rate Question
Q: What is the dislocation rate after primary THA via Hardinge approach compared to posterior approach? A: Hardinge (direct lateral) has lower dislocation rate (approximately 3%) compared to posterior approach (5-7%). However, Hardinge has higher risk of abductor dysfunction.
Closure Question
Q: What is the most critical step in closing a Hardinge approach? A: Meticulous repair of the gluteus medius back to the greater trochanter using non-absorbable suture (e.g., No. 2 Ethibond). Poor repair causes Trendelenburg gait and abductor dysfunction in up to 20% of patients.
Australian Context
AOANJRR Data:
- Direct lateral approach is the most common THA approach in Australia (40% market share)
- Posterior approach second (35%)
- Anterior approach growing (20%)
- Regional variation: More lateral in Victoria/SA, more posterior in NSW/QLD
Training implications:
- Most Australian orthopaedic trainees learn Hardinge as primary THA approach
- Important for Orthopaedic exam - examiners expect detailed knowledge
- Familiarity with approach selection based on patient factors
Medico-legal considerations:
- Abductor dysfunction is a recognized complication - must be in consent
- Superior gluteal nerve injury is preventable - staying under 5cm from GT is standard of care
- Documentation of repair technique important if post-op abductor weakness
Exam Preparation
For Orthopaedic exam, you must be able to describe the Hardinge approach in detail including: positioning, skin incision, muscle intervals (TFL split, GM split at musculotendinous junction), structures at risk (superior gluteal nerve 5cm from GT), and closure technique (GM repair with non-absorbable suture). Know the AOANJRR data showing it's the most common approach in Australia.
HARDINGE DIRECT LATERAL APPROACH
High-Yield Exam Summary