Antegrade Femoral Nailing (Piriformis vs Trochanteric Entry)

Indication. Reamed antegrade intramedullary nailing is the GOLD STANDARD for the adult femoral shaft (diaphyseal) fracture. It is also the workhorse for subtrochanteric fractures (with a trochanteric-entry nail), for ipsilateral femoral shaft and neck fractures (after the neck is prioritised), and for pathological or impending pathological fractures of the diaphysis. Standard indications

• Femoral shaft (diaphyseal) fractures — reamed antegrade nailing is the benchmark
• Subtrochanteric femoral fractures — with a trochanteric-entry (cephalomedullary or long reconstruction) nail
• Ipsilateral femoral shaft and neck fractures — the femoral NECK takes priority; the shaft is then managed with a nail or a retrograde or plate strategy depending on neck fixation
• Pathological or impending pathological fractures of the diaphysis (prophylactic stabilisation) Relative indications — segmental fractures (a length-stable construct restoring alignment), selected distal-third shaft fractures (retrograde nailing or plating may be preferable nearer the knee), and femoral shaft nonunion (exchange reamed nailing). Contraindications
• Absolute — active infection at the entry site or along the canal (without staged management); and piriformis entry in the skeletally immature or adolescent femur (AVN risk via the medial femoral circumflex artery).
• Relative — unstable or borderline polytrauma physiology (favours damage control orthopaedics), pre-existing femoral deformity or retained hardware preventing canal passage, and very distal or very proximal fracture extension where nail fixation is biomechanically poor. The one decision that matters — entry point. Every antegrade femoral nail begins with the same choice of start point, and the start point dictates both the reduction and the implant:

Timing — match the intervention to the physiology. The decision between early definitive nailing and damage control is driven by the patient's response to resuscitation (lactate clearance, base deficit) rather than a fixed clock:

Special situations

• Skeletally immature or adolescent femur — avoid piriformis entry (medial femoral circumflex artery injury, femoral head AVN). Choose by age and weight: flexible (elastic) nails for most school-age children with a length-stable shaft fracture; a lateral-entry rigid (trochanteric) nail or sub-muscular bridge plating for older, heavier adolescents and length-unstable patterns. Respect the proximal femoral physis and the trochanteric apophysis.
• Bilateral femoral shaft fractures — a higher-energy injury carrying greater systemic insult and mortality; have a lower threshold for damage control (bilateral external fixation) in the borderline patient, with staged definitive nailing once resuscitated, and vigilance for fat embolism syndrome and ARDS.
• Ipsilateral femoral neck and shaft fracture — the femoral NECK is the priority and is easily missed; scrutinise the hip on the trauma series, stabilise the neck reliably, and choose a shaft strategy (retrograde nail, plate, or a construct compatible with neck fixation) around it. Consent specifically for malrotation and malreduction, varus (subtrochanteric), nonunion or delayed union, AVN of the femoral head (immature femur, piriformis entry), fat embolism and ARDS, infection, nerve injury (pudendal from the perineal post; rarely sciatic or peroneal from positioning), heterotopic ossification, hardware failure, and the possible need for dynamisation or revision. Setup. Two common positions — a fracture (traction) table (supine or lateral, longitudinal traction for length and reduction, mandating a well-padded perineal post and careful traction limits) or a free-leg (flat radiolucent) table (faster set-up, easier rotational control and access for assisted reduction, manual traction; preferred by many for subtrochanteric patterns). Image intensify with a clear view of the hip (entry, neck) and the knee (length, distal locking, distal alignment), and drape the contralateral limb accessible if rotation comparison on the table is planned.

The goal: choose the correct entry point, achieve and hold reduction before reaming, deliver a nail matched to the entry across the reduced fracture, and lock it in correct length and rotation. The exposure is the proximal entry — laid out in full as the opening steps below — and the whole sequence turns on reducing the fracture before the nail commits the alignment.

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Immediate (Day 0 to 2)

• Neurovascular check — confirm distal pulses and sensation; specifically check perineal sensation if a traction table and post were used (pudendal nerve).
• Respiratory monitoring — vigilance for fat embolism syndrome (hypoxia, confusion, petechiae) in the first 24 to 72 hours, particularly with a chest injury or bilateral femoral fractures.
• Multimodal analgesia and chemical plus mechanical thromboprophylaxis — a femoral fracture is high VTE risk.
• Radiographs — AP and lateral of the full femur including hip and knee to document reduction, alignment, length and locking. Weight-bearing
• Length-stable patterns (transverse, short oblique, stable comminution) — often early weight-bearing as tolerated.
• Length-unstable, highly comminuted or subtrochanteric patterns — protected or partial weight-bearing initially, advancing as callus appears; individualise to construct stability.
• Early mobilisation reduces pulmonary and thromboembolic complications. Rehabilitation — early knee and hip range of motion; quadriceps and abductor strengthening (abductor function may be affected by the entry, especially piriformis); gait re-education and any Trendelenburg from abductor compromise; progressive return to function over 3 to 6 months with union typically at 3 to 6 months on serial radiographs. Complications

Proximal femoral entry anatomy. The two start points define the operation. The piriformis fossa lies just medial to the tip of the greater trochanter, at the base of the femoral neck; it is collinear with the medullary canal, so a straight nail introduced here lies in line with the shaft and reduces a diaphyseal fracture anatomically — but the start point is close to the deep branch of the medial femoral circumflex artery posteriorly, passes through the abductor insertion and deep external rotators, and is technically demanding to localise, particularly in the muscular or obese patient. The greater trochanter tip start point (slightly medial to the very tip on the AP, central on the lateral) is off-axis to the canal; a straight nail would drive the shaft into varus, so trochanteric-entry nails are manufactured with a proximal mediolateral bend of about 4 to 6 degrees. Medial femoral circumflex artery — the femoral head supply. The medial femoral circumflex artery, a branch of the profunda femoris, gives off the deep branch that ascends posterior to the femoral neck and terminates as the lateral epiphyseal (retinacular) arteries — the dominant supply to both the adult and the paediatric femoral head. A medially placed proximal femoral start point can injure this vessel; this is the anatomical basis for avoiding piriformis entry in children and adolescents, where AVN of the femoral head is a recognised, devastating complication. Femoral canal and isthmus. The canal narrows at the isthmus (mid-diaphysis), where the nail engages cortical bone and where the reaming diameter is set. The femur has a natural anterior bow (radius of curvature about 120 cm); a nail with a mismatched radius of curvature risks anterior cortical perforation distally, especially in the older patient with a more bowed femur. Femoral neck anteversion of about 10 to 15 degrees is the reference for setting rotation — match the contralateral side. Subtrochanteric deforming forces. The subtrochanteric region (from the lesser trochanter to about 5 cm distal) is dominated by powerful muscle attachments that deform the proximal fragment into the classic varus and procurvatum malreduction: