Comprehensive guide to the Hardinge direct lateral approach to the hip - indications, technique, internervous plane, structures at risk, and surgical pearls for Orthopaedic exam
Reviewed by OrthoVellum Editorial Team
Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
Transgluteal | Superior Gluteal Nerve at Risk | Most Common THA Approach in Australia
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.
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.
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.
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.
| Clinical Scenario | Hardinge (Direct Lateral) | Alternative | Key Pearl |
|---|---|---|---|
| Primary THA, standard anatomy | EXCELLENT choice - good exposure, low dislocation | Posterior if revision or DDH | Most common approach in Australia (AOANJRR) |
| Revision THA, need acetabular exposure | ADEQUATE if minor revision | Posterior better for major revision | Limited posterior column access |
| DDH with high hip center | DIFFICULT - limited proximal reach | Posterior or anterolateral better | Superior gluteal nerve at risk with proximal extension |
| Femoral neck fracture (hemiarthroplasty) | EXCELLENT - fast, stable, familiar | Posterior also acceptable | Lower dislocation than posterior, faster rehab |
Memory Hook:HARDINGE guides you through the direct lateral approach - remember the nerve danger zone!
Memory Hook:SGA exits 5cm proximal to GT - stay distal to avoid disaster
Memory Hook:A good REPAIR prevents Trendelenburg gait - the most important step in Hardinge closure!
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:
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:
Primary indications:
Advantages:
Disadvantages:
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.
Muscular layers (superficial to deep):
Neurovascular structures:
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:
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:
Biomechanical considerations:
Abductor mechanism:
Muscle fiber architecture:
The Direct Lateral (Hardinge) approach involves splitting muscles that are supplied by the same nerve.
This is distinguishing feature from the Anterior (Smith-Petersen) which has a TRUE internervous plane.
Original McFarland-Osborne (1954):
Hardinge Modification (1982):
Dall Modification:
The Hardinge modification is the standard technique described here.
Preoperative Assessment:
History:
Physical Examination:
Specific assessment for Hardinge approach:
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.
Imaging:
Essential:
Templating requirements:
Advanced imaging (selective):
Laboratory:
Step 1: Is patient suitable for ANY THA?
Step 2: Hardinge approach considerations
Ideal candidates:
Consider alternatives if:
Surgeon experience is the most important factor in approach selection.
Lateral decubitus position on radiolucent table with affected hip up.
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.
Landmarks:
Incision:
Superficial dissection:
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.
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.
| Structure | Location | Mechanism of Injury | Prevention |
|---|---|---|---|
| Superior gluteal nerve | 5cm proximal to GT | Proximal extension of GM split | Limit dissection to 4cm proximal to GT, measure with ruler |
| Gluteus medius muscle | Hip abductor | Excessive splitting, poor repair | Split anterior half only, meticulous repair with non-absorbable suture |
| Femoral nerve | Anterior to hip (psoas interval) | Anterior retractor placement | Place anterior retractor under direct vision, feel for femoral pulse |
| Sciatic nerve | Posterior to hip | Posterior retractor, leg lengthening | Place posterior retractor carefully, avoid excessive lengthening (under 4cm) |
| Lateral femoral cutaneous nerve | Anterolateral thigh | Proximal incision extension | Keep incision posterior to ASIS, limit proximal extension |
Abductor dysfunction:
Heterotopic ossification:
Dislocation:
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).
Immediate Postoperative Period (Day 0-2):
Pain Management:
Mobilization:
DVT Prophylaxis:
Hip Precautions:
Wound Care:
Discharge:
Rehabilitation:
Weeks 1-6:
Weeks 6-12:
Beyond 3 months:
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).
Functional Outcomes:
Short-term (under 2 years):
Long-term (over 10 years):
Approach-Specific Outcomes:
Abductor function:
Dislocation comparison:
| Approach | Dislocation Rate |
|---|---|
| Direct Lateral | 2-3% |
| Posterior | 5-7% |
| Anterior | 1-2% |
Heterotopic ossification:
Prognostic Factors:
Good prognosis:
Poorer prognosis:
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.
Practice these scenarios to excel in your viva examination
"Walk me through the Hardinge direct lateral approach to the hip. What are the key anatomical landmarks and structures at risk?"
"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?"
"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?"
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.
AOANJRR Data:
Training implications:
Medico-legal considerations:
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.
High-Yield Exam Summary