Posterior Approach to the Femur

Indications

• middle 3/5 of femur
• exploration of sciatic nerve

Essence

• between biceps femoris & vastus lateralis

Principles

• Proximal
  • lateral to biceps muscles
• Distal
  • Medial to biceps muscle

Position

• Prone on operating table
• Longitudinal pads under chest & abdomen to allow expansion

Landmarks

• Gluteal folds

Incision

• Straight longitudinal incision centred over the midline of the posterior aspect of the thigh

Internervous Plane

• Lateral intermuscular septum
• Biceps femoris muscle
  • Sciatic nerve

Superficial Dissection

• Incise deep fascia of thigh taking care not to damage
  • Posterior femoral cutaneous nerve
• Identify & develop the plane between biceps femoris & vastus lateralis (lateral intermuscular septum) using blunt dissection

Deep Dissection

• Proximally
  • Retract the long head of biceps medially
  • Identify the short head of biceps & detach it from the femoral origin by sharp dissection
  • Reflect it medially to expose the posterior aspect of femur
• Distally
  • Retract the long head of biceps laterally
  • Expose sciatic nerve & retract it laterally to expose femur
  • Incise the periosteum longitudinally

Dangers

• Nerves
  • Posterior femoral cutaneous
    • Runs underneath deep fascia between biceps & semitendinosus
  • Sciatic nerve