Comprehensive guide to the medial approach to the hip - Ludloff approach, adductor interval, obturator neurovascular structures, and applications in DDH and hip surgery for Orthopaedic exam
Reviewed by OrthoVellum Editorial Team
Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
Historical Pediatric Approach | Obturator Nerve at Risk | Limited Modern Applications
The medial approach is primarily historical and used almost exclusively in pediatric orthopedics for DDH open reduction. Adult arthroplasty surgeons rarely use this approach. Know it exists, but focus exam preparation on anterior, lateral, and posterior approaches.
The obturator nerve runs 2-3cm from the skin incision, deep to the pectineus muscle. Injury causes weakness of adduction and sensory loss over medial thigh. The anterior branch runs between adductor longus and brevis; posterior branch between adductor brevis and magnus.
The medial femoral circumflex artery (MFCA) provides critical blood supply to the femoral head. It runs between pectineus and iliopsoas, then posterior to the femoral neck. Injury can cause AVN of femoral head - catastrophic in pediatric patients.
There is no true internervous plane in the medial approach. The adductor interval (between adductor longus and gracilis/adductor brevis) involves muscles with shared obturator innervation. This approach works by muscle retraction, not nerve-sparing dissection.
| Clinical Scenario | Medial Approach | Better Alternative | Key Pearl |
|---|---|---|---|
| Primary THA adult patient | NOT INDICATED | Anterior, lateral, or posterior | Medial approach has no role in routine THA |
| DDH open reduction (infant) | CLASSICAL INDICATION | Smith-Petersen if over 18 months | Ludloff approach for under 18 months age |
| Psoas tendon release for snapping hip | Can be used (alternative) | Arthroscopic release preferred | Open medial approach rarely needed now |
| Medial capsule pathology | Possible niche indication | Usually combined anterior approach | Very limited modern applications |
| Revision THA | NOT INDICATED | Posterior, lateral, or extended approaches | Inadequate exposure for revision work |
Memory Hook:MEDIAL approach puts MEDIAL structures at risk - especially the MFCA!
Memory Hook:OBTURATOR nerve - know its course to protect it during medial approach!
The medial approach to the hip was first described by Karl Ludloff in 1908 for open reduction of congenital hip dislocation (DDH) in infants. It gained popularity in the early 20th century as one of several approaches for managing DDH before modern understanding of closed reduction and Pavlik harness treatment.
The Ludloff medial approach has very limited applications in modern orthopedic surgery:
Primary Current Use:
Rare Adult Applications:
NOT Used For:
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The medial approach works through the adductor compartment of the thigh:
Superficial Layer (Anterior to Posterior):
Deep Layer:
Obturator Nerve:
Medial Femoral Circumflex Artery (MFCA):
Other Structures:
The "interval" used in the medial approach is between:
This is NOT a true internervous plane because both muscles are supplied by the obturator nerve. The approach works by retracting muscles, not by exploiting nerve boundaries.
Unlike the posterior approach to the hip (which has a true internervous plane between inferior gluteal and superior gluteal nerve territories), the medial approach has NO true internervous plane.
Why Not an Internervous Plane?
The surgical dissection passes through the adductor compartment, where all muscles are innervated by the obturator nerve:
Clinical Implication:
Comparison with Other Hip Approaches:
| Approach | Internervous Plane | Significance |
|---|---|---|
| Posterior (Moore) | TRUE - Gmax (inf gluteal) vs GM (sup gluteal) | Only true internervous plane |
| Anterior (Smith-Petersen) | TRUE - Sartorius (femoral) vs TFL (sup gluteal) | Well-defined plane |
| Direct Lateral (Hardinge) | FALSE - Splits gluteus medius | Risk of abductor weakness |
| Medial (Ludloff) | FALSE - Through adductor muscles | All obturator innervated |
Examination Pearl: When asked about the internervous plane of the medial approach, the correct answer is: "There is no true internervous plane. The approach passes through the adductor interval, but all surrounding muscles are supplied by the obturator nerve."
Standard Position: The patient is positioned supine on a radiolucent table with the affected hip exposed.
Key Positioning Elements:
Supine Position
Hip Position
Knee Position
Contralateral Leg
Alternative: Frog-Leg Position:
Imaging Considerations:
Draping:
The medial approach was developed to address specific pathology that required medial access to the hip joint:
Historical Indication - DDH Open Reduction:
In developmental dysplasia of the hip (DDH), the femoral head is dislocated posterosuperiorly from the acetabulum. The medial approach allows:
Release of Obstructions to Reduction:
Direct Access to Capsule:
Preservation of Blood Supply:
Biomechanical Considerations:
The approach disrupts:
The approach preserves:
Limitations for Adult Hip Surgery:
Cannot Visualize Acetabulum Well:
Cannot Expose Femoral Shaft:
High Risk to MFCA:
| Variant | Key Features | Primary Use |
|---|---|---|
| Ludloff (Classic) | Through adductor interval, pectineus retracted | DDH open reduction |
| Ferguson | Medial to adductor longus | Modified DDH reduction |
| Weinstein | Modified Ludloff with extended capsulotomy | DDH in older infants |
| Anteromedial | Combined anterior + medial elements | Extended exposure |
Ludloff Approach (1908):
Ferguson Approach:
Both approaches are primarily pediatric and rarely used in adult orthopedic surgery.
History:
Physical Examination:
Hip Range of Motion:
Adductor Assessment:
Gait Pattern (if ambulatory):
Leg Length:
Special Tests:
Plain Radiography:
Ultrasound (Pediatric DDH):
Arthrography:
MRI:
CT Scan:
| Parameter | Assessment | Significance |
|---|---|---|
| Patient age | Under 18 months ideal | Older = anterior approach preferred |
| DDH severity | Tonnis classification | Higher grades may need anterior approach |
| Previous surgery | Any prior incisions | May affect approach choice |
| Bilateral DDH | Both hips involved | Staged procedures vs bilateral |
| Femoral head vascularity | Pre-op MRI if concern | AVN risk assessment |
Is the patient an ADULT with hip pathology?
Is this a PEDIATRIC DDH case?
Is this for psoas tendon release?
Key Decision Points:
In Orthopaedic exam context, focus on knowing indications and contraindications rather than detailed technique.
Step 1: Incision and Superficial Dissection
Step 2: Interval Identification
Step 3: Deep Dissection
Step 4: Iliopsoas Identification
Continue with capsule exposure and reduction as described below.
Medial Femoral Circumflex Artery: The MFCA runs posterior to the iliopsoas and around the femoral neck. It is the PRIMARY blood supply to the femoral head. Any injury can cause AVN. Be extremely careful when dissecting near the lesser trochanter and capsule.
Obturator Nerve: The anterior division runs between adductor longus and brevis. The posterior division runs between adductor brevis and magnus. Both are at risk during deep dissection. Excessive retraction causes neuropraxia.
| Structure | Location/Risk | Prevention | Management if Injured |
|---|---|---|---|
| Obturator nerve | Between adductor muscles, 2-3cm deep | Careful retraction, identify nerve, avoid excessive traction | Document deficit, observation if neuropraxia, repair if transection |
| Medial femoral circumflex artery | Posterior to iliopsoas, around femoral neck | Careful dissection, meticulous hemostasis, avoid posterior dissection | Ligate if bleeding, monitor for AVN post-operatively |
| Femoral vessels | Lateral to pectineus, in femoral triangle | Do not dissect lateral to pectineus, identify femoral pulse | Direct compression, vascular surgery consultation if injury |
| Profunda femoris artery | Origin of MFCA, deep in thigh | Stay superficial to this level, careful hemostasis | Ligate branches as needed |
Avascular Necrosis (AVN) of Femoral Head:
Obturator Nerve Palsy:
Redislocation/Subluxation (DDH cases):
AVN Risk in DDH Surgery
AVN of the femoral head is the most feared complication of open reduction for DDH. The medial femoral circumflex artery supplies most of the femoral head blood. It runs in the surgical field of the medial approach. Even with perfect technique, AVN can occur due to pressure effects from reduction. Always counsel families about this risk.
Immediate Post-operative Period:
Spica Cast Care:
Imaging Follow-up:
Mobilization After Cast Removal:
Long-term Follow-up:
DDH Open Reduction via Medial Approach:
| Outcome Measure | Good Result | Moderate Result | Poor Result |
|---|---|---|---|
| Severin Classification | Grade I-II: Normal/near-normal | Grade III: Moderate dysplasia | Grade IV-VI: Severe dysplasia/subluxation |
| AVN (Kalamchi-MacEwen) | None or Grade I | Grade II-III | Grade IV: Severe head collapse |
| Need for further surgery | None | Pelvic osteotomy later | Multiple surgeries, THA eventually |
Favorable Prognostic Factors:
Poorer Prognosis:
Severin Classification
The Severin classification is used to grade radiographic outcomes after DDH treatment:
Grades I-II are considered satisfactory. This classification is assessed at skeletal maturity.
Practice these scenarios to excel in your viva examination
"Describe the medial approach to the hip. What is the internervous plane and what are the main structures at risk?"
"A 10-month-old infant has failed closed reduction for DDH. The pediatric orthopedic team is planning open reduction. What approach options exist and what is the role of the medial approach?"
"Following a medial approach for hip surgery, the patient has weakness of hip adduction. How do you assess and manage this?"
Relevance to Orthopaedic Exam: The medial approach to the hip is LOW YIELD for the adult reconstruction and general orthopedic components of the Orthopaedic exam. Key points to know:
Australian Practice:
For Orthopaedic Candidates: Focus your hip approach preparation on:
Know the medial approach exists, its basic anatomy and indications, but do not spend excessive time on detailed technique.
Orthopaedic Exam Priority
If asked about hip approaches in the Orthopaedic viva, start with the approaches you would actually use in practice (anterior, lateral, posterior). If asked specifically about the medial approach, demonstrate you know it exists, its primary use (pediatric DDH), and why it is not used for adult THA (limited exposure, MFCA risk).
High-Yield Exam Summary