Femur - Anteromedial Approach

What it exposes. The anteromedial approach is a versatile corridor giving direct access to the medial and anterior aspects of the femoral shaft through the interval between sartorius (medial) and vastus medialis (lateral). It is the workhorse exposure for minimally invasive plate osteosynthesis (MIPO) of the distal femur, medial plate fixation of the shaft, bone grafting of nonunions, and revision work where the lateral side has already been operated on. Why anteromedial (and not lateral). Both sartorius and vastus medialis are innervated by the femoral nerve, so the interval is technically a functional rather than a true internervous plane. It is nevertheless safe: the nerve branches enter from different directions (sartorius from its deep surface, vastus medialis from its lateral surface) and the muscles have distinct functions, so dissection between them denervates nothing of consequence. The approach has grown in popularity for modern MIPO techniques and is especially attractive when the lateral femur is scarred, comminuted, or unsuitable for fixation — it offers a superficial, relatively avascular plane and virgin medial tissue. The critical structure at risk is the femoral neurovascular bundle. In the femoral triangle the arrangement lateral-to-medial is remembered as NAVEL (Nerve, Artery, Vein, Empty space, Lymphatics). In the mid-thigh these structures run through the subsartorial (Hunter's) canal, bounded by vastus medialis laterally, adductor longus and magnus medially, and sartorius superficially.

Position & landmarks. Position the patient supine on a radiolucent table (essential for fluoroscopy); a standard fracture table is generally not required. Place a bump under the ipsilateral hip to tilt the pelvis and bring the medial thigh anteriorly. Position the limb with the hip abducted 15 to 20 degrees and externally rotated 10 to 15 degrees, and the knee flexed 10 to 20 degrees on a sterile bump to relax the quadriceps. The C-arm comes from the contralateral side. Palpate and mark the ASIS and pubic tubercle (defining the inguinal ligament), the mid-inguinal point (midway between ASIS and pubic symphysis — the femoral artery), the adductor tubercle on the medial femoral condyle (distal landmark), and the oblique course of sartorius. The incision is centred between the ASIS and the adductor tubercle. Contraindications. Active infection in the surgical field (cellulitis, abscess, open contaminated medial wound) is an absolute contraindication to elective use — stage with debridement and temporary external fixation in trauma. Relative contraindications are massive medial soft-tissue loss (wound-healling and coverage concern — consider a lateral route or flap) and morbid obesity (deep field, difficult retraction). Threatened limb viability from vascular insufficiency is usually a contraindication — except that an acute vascular injury needing combined repair turns it into an indication. Assess high-risk limbs with ankle-brachial indices and CT angiography. Anaesthesia. General anaesthesia is preferred for optimal muscle relaxation, but neuraxial blockade suits elderly patients with cardiopulmonary comorbidity. For MIPO, an adductor canal or femoral nerve block gives targeted analgesia while preserving motor function — coordinate timing with the surgeon, as a pre-operative femoral block can blur landmark identification.

Work down through the medial thigh in layers: incise over the sartorius–vastus medialis interval, open the subsartorial canal carefully to find and protect the femoral vessels and saphenous nerve, then elevate vastus medialis subperiosteally off the shaft.

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Structures at risk, by layer

Complications. Saphenous nerve injury (5 to 15 percent, usually neuropraxia) causes medial-leg numbness or a painful neuroma — prevent it as above; a refractory neuroma may need excision and proximal-stump burial. Femoral vessel injury is the most serious risk — arterial injury presents with pulsatile bleeding, an expanding haematoma or loss of distal pulses; manage with immediate direct pressure, proximal and distal control, and urgent vascular surgery (primary repair with 5-0 or 6-0 Prolene if a clean laceration and help is delayed). Haematoma is minimised by meticulous haostasis, a drain where indicated, a compression dressing, and delaying the first chemoprophylaxis dose 6 to 12 hours; tranexamic acid may help in high-risk patients. Surgical site infection occurs in about 1 to 3 percent — superficial cases respond to antibiotics, deep cases need debridement and sometimes hardware removal. Thigh compartment syndrome is rare but a surgical emergency — pain with passive stretch demands urgent four-compartment fasciotomy. Extensile options. Extend proximally along the radial border of sartorius toward the femoral triangle to reach the femoral vessels for proximal control or to address proximal-shaft pathology. Extend distally along the medial border of the patella toward the adductor tubercle for the distal femur and for MIPO submuscular plate insertion — this distal extension is where the saphenous nerve is most vulnerable. Closure. Achieve meticulous haemostasis and inspect the canal to confirm the vessels are intact. Close the fascia lata with 0 or 1 absorbable suture; the subsartorial canal roof need not be formally closed (it is thin and closure may compress the bundle). Let sartorius fall back over the vessels to provide soft-tissue cover, then close subcutaneous tissue (2-0 or 3-0 absorbable) and skin (staples, subcuticular suture or adhesive) over a sterile compression dressing.

• MIPO / submuscular locked plating of distal femur fractures — the principal modern use, achieving high union without grafting.
• Medial plate fixation of middle-third femoral shaft fractures — when the lateral side is comminuted, has bone loss, or is unsuitable for fixation.
• Periprosthetic Vancouver/UCS B1 fractures around a well-fixed hip stem — medial plating avoids the scarred lateral tissue and abductors; distinguishing B1 (fix the fracture) from B2/B3 (revise the stem) is the decision pivot.
• Bone grafting of atrophic nonunions — direct medial access to the defect plus medial plating for stability, avoiding a previously operated lateral plane.
• Corrective osteotomy for femoral malunion and biopsy or excision of medial femoral tumours (benign and, with limb-salvage reconstruction, malignant).
• Combined orthopaedic-vascular procedures for ipsilateral femoral fracture with vascular injury — a single shared medial field.

At a glance. The anteromedial approach reaches the medial femoral shaft through the interval between sartorius (medial) and vastus medialis (lateral) — both femoral-nerve innervated, making this a functional but not true internervous plane. Key uses are MIPO of the distal femur (around 93 percent union without grafting), medial plating, nonunion grafting, and revision where the lateral side is scarred. The subsartorial (Hunter's) canal carries the femoral vessels and must be identified to avoid catastrophic injury; its boundaries are sartorius (roof), vastus medialis (lateral) and the adductors (medial). The saphenous nerve exits the canal at mid-thigh and is the most commonly injured structure (5 to 15 percent). Position supine with the hip slightly abducted and externally rotated.

Epidemiology. Femoral shaft fractures occur worldwide at roughly 10 to 21 per 100,000 person-years with a classic bimodal distribution: high-energy injuries in young men and low-energy fragility fractures in older women. Periprosthetic femoral fractures around hip stems are a fast-growing burden across all major registries as arthroplasty volumes and patient age rise. Vancouver/UCS type B fractures (around the stem) are the commonest periprosthetic pattern; type B1 (well-fixed stem) is the subgroup managed by fixation rather than revision and is therefore the principal indication for plating via this corridor. Registry evidence — periprosthetic femoral fractures

Global practice variation. Vascular surgery availability is the key system-level determinant for this approach. In tertiary trauma centres with on-site vascular cover, combined orthopaedic-vascular procedures can be undertaken safely. In resource-limited or remote settings without immediate vascular backup, a high-risk anteromedial dissection is best deferred to scheduled lists with full teams present, or an alternative approach selected; damage-control external fixation and transfer to a centre with vascular capability is the safe default for the acutely injured limb with vascular concern.