Hip Medial Approach (Ludloff)

What it exposes. The medial approach gives direct access to the medial hip capsule, the lesser trochanter and iliopsoas tendon, and the soft-tissue obstructions to reduction in DDH (pulvinar, ligamentum teres, transverse acetabular ligament). It is the classical exposure for open reduction of DDH in infants, and an occasional route for an open psoas release. Why medial — and why it is essentially paediatric. Karl Ludloff described the approach in 1908 for open reduction of congenital hip dislocation. It offers a cosmetic groin-crease incision, direct access to the medial capsule and the obstacles to reduction, and avoids disturbing the abductors or short external rotators. Its limitations are severe: the acetabulum cannot be visualised well enough to place an implant, the femoral shaft is unreachable, and the femoral head blood supply (the MFCA) lies in the field. For these reasons it has no role in primary or revision THA, acetabular fracture fixation, or femoral neck fracture fixation, and even in DDH its use is confined to the youngest infants. The adductor interval and the absence of an internervous plane. The approach works through the adductor compartment of the thigh. The superficial layer (anterior to posterior) is pectineus (femoral, or accessory obturator in about 10 percent), adductor longus (obturator, anterior division) and gracilis (obturator, anterior division); the deep layer is adductor brevis, adductor magnus (adductor part) and obturator externus. The interval used lies between pectineus (laterally) and adductor longus (medially), or between adductor longus (anterior) and gracilis (posterior). Because every muscle in this compartment is supplied by the obturator nerve, there is no true internervous plane — the approach succeeds by retracting muscle, not by exploiting a nerve boundary, in stark contrast to the posterior hip approach.

When to choose it. Open reduction is reserved for hips that fail or are unsuitable for closed reduction; the medial option is mainly for the youngest infants.

Age-based approach selection in DDH. - Under 6 months — closed management with a Pavlik harness.

• 6 to 18 months — closed reduction or open reduction (medial or anterior).
• 18 months to 3 years — open reduction plus pelvic osteotomy, usually through an anterior approach.
• Over 3 years — anterior approach preferred, with pelvic osteotomy. Severity is graded with the Tönnis classification, which informs whether open reduction (and which approach) is needed.

Position and landmarks. The patient is supine on a radiolucent table with the affected hip flexed about 45 degrees, externally rotated about 45 degrees and abducted to relax the adductors and open the interval; the knee is flexed 45 to 90 degrees. A frog-leg (figure-of-4) position is often used in infants. The contralateral leg is secured out of the way. The incision is centred over the adductor longus origin in the groin crease, about 2 to 3 cm medial to the femoral pulse. Drape circumferentially, exposing the medial thigh from groin crease to mid-thigh, and protect and isolate the genitalia. Fluoroscopy and an intra-operative arthrogram are used to confirm reduction.

Work from skin down to the medial capsule through the adductor interval, protecting the obturator nerve and the medial femoral circumflex artery at every layer, then release the obstacles to reduction.

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Structures at risk, by layer. The danger of this approach is concentrated in two structures — the obturator nerve and the medial femoral circumflex artery — with the femoral bundle at risk if dissection strays lateral to pectineus.

Avascular necrosis of the femoral head. AVN is the most feared complication. The pooled rate after open reduction is approximately 18 to 20 percent, and it does not differ significantly between the medial and anterior approaches (meta-analysis 18.7 percent medial vs 19.6 percent anterior). Individual series range widely, from 5 to 43 percent. Mechanism is injury to the deep branch of the MFCA or pressure on the femoral head from over-reduction or wide-abduction casting. Risk factors include a more severe or higher dislocation, an absent ossific nucleus, and immobilisation in excessive abduction (60 degrees or more); pooled data did not confirm age over 12 months as an independent risk factor. Prevention rests on meticulous deep dissection away from the posterosuperior neck, gentle reduction, and avoidance of extreme abduction in the spica. AVN is graded with the Kalamchi and MacEwen classification.

Obturator nerve palsy. Rare (under 2 percent) with careful technique. It presents as weakness of hip adduction with sensory loss over the medial thigh — anterior division injury affects adductor longus, brevis and gracilis, posterior division injury affects adductor magnus and obturator externus. Most cases are a neuropraxia from retraction and recover over weeks to months; EMG at 3 to 4 weeks classifies the injury, and exploration is considered if there is no recovery by 3 to 6 months. Redislocation or subluxation (DDH). Reported in 5 to 10 percent of series, from inadequate reduction, instability, or non-compliance with immobilisation. Prevention is confirmation of reduction with arthrography and adequate immobilisation; management is repeat closed or open reduction, with consideration of a pelvic osteotomy. Residual acetabular dysplasia — not AVN — is the main driver of long-term failure and may require later osteotomy. Radiographic outcome is graded with the Severin classification, assessed at skeletal maturity (grades I to II are satisfactory).

Variants of the medial approach.

Extensile options and closure. Extension is limited — the incision can be carried proximally along adductor longus for a little more proximal exposure, but the approach cannot be usefully extended to the acetabulum or femoral shaft. Closure returns the muscles to their anatomical position; the capsule may be closed loosely or left open. A hip spica is applied in the human position for 6 to 12 weeks, with post-reduction imaging to confirm reduction and serial radiographs to skeletal maturity to monitor for residual dysplasia and AVN.

• Developmental dysplasia of the hip — open reduction in infants is the principal operation done through this exposure.
• Psoas (iliopsoas) tendon release at the lesser trochanter — now mostly performed arthroscopically, but accessible here.
• Access to the medial hip capsule for rare niche pathology.
• Not suitable for primary or revision total hip arthroplasty, acetabular fracture fixation, femoral neck fixation, or femoral osteotomy — inadequate exposure and MFCA risk.

Guidelines, registries and global practice. The medial (Ludloff) approach is a paediatric open-reduction technique. Across major societies, open reduction is reserved for hips that fail or are unsuitable for closed reduction, but the threshold for choosing the medial over the anterior approach varies by surgeon and region. - AAOS (US) clinical practice guideline — open reduction for hips failing or unsuitable for closed reduction; medial vs anterior left to surgeon judgement.

• BSCOS / BOA (UK) — some units favour the medial approach in the youngest infants (typically under 12 months) where capsulorrhaphy or a concurrent osteotomy is not needed.
• EPOS / European paediatric practice — anterior (Smith-Petersen) preferred once a pelvic osteotomy is anticipated or before the ossific nucleus has appeared.
• Resource-variable settings — late-presenting, higher-grade dislocations are more common, pushing practice toward the anterior approach with concomitant bony procedures. Evidence convergence. Across pooled series the AVN rate after medial open reduction is broadly comparable to the anterior approach (meta-analysis 18.7 percent medial vs 19.6 percent anterior; no significant difference). Long-term failure after the medial approach is driven mainly by residual acetabular dysplasia, not AVN — about one in five hips needs further surgery in long-follow-up cohorts. Earlier reduction (6 months or younger) is associated with very low rates of later bony surgery without an excess of severe AVN.