Anteromedial Approach to Femur

Anteromedial Approach to Femur indications:

The anteromedial approach to femur provides an excellent view of the lower two thirds of the femur and the knee joint.

The anteromedial approach to femur uses include:

1. Open reduction and internal fixation (ORIF) of distal femur fractures, particularly fractures with intra-articular extension that require a medial plate.
2. Open reduction and internal fixation of femoral shaft fractures (Limited to distal 2/3 of femur by the presence of the femoral neurovascular bundle).
3. Treatment of chronic osteomyelitis.
4. Biopsy and treatment of bone tumors of the femur.
5. Quadriceps plasty.

Position of the Patient

• Place the patient supine on the operating table.
• Consider bump under contralateral hip to facilitate access to the medial femur

Landmarks and Incision

• Landmarks:
  • Vastus medialis muscle.
• Incision:
  • Make a 10- to 15-cm longitudinal incision on the anteromedial aspect of the thigh over the interval between the rectus femoris and vastus medialis muscles.
  • Extend the incision distally along the medial edge of the patella to the joint line of the knee, if the knee joint must be opened.
  • The exact length of the incision depends on the pathology being treated

Internervous plane

• There is no internervous plane for the anteromedial approach to femur, the dissection descends between the vastus medialis and rectus femoris muscles, both of which are supplied by the femoral nerve.
• The intermuscular plane can be used safely to expose the distal two thirds of the femur because both muscles receive their nerve supplies well up in the thigh.

Superficial dissection

• Incise the fascia lata (deep fascia) in line with the skin incision, and identify the interval between the vastus
  medialis and rectus femoris muscles, develop this plane by retracting the rectus femoris laterally.

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Deep dissection

• Begin distally, opening the capsule of the knee joint in line with the skin incision by cutting through the medial patellar retinaculum.
• Continue proximally, splitting the quadriceps tendon almost on its medial border.
• Open up the plane by sharp dissection, staying within the substance of the quadriceps tendon and leaving a small cuff of the tendon with the vastus medialis attached to it.
• This preserves the insertion of these fibers and allows easy closure. If the vastus medialis is stripped off the quadriceps tendon, it is very difficult to reinsert, and muscle function will be compromised.
• Next, continue to develop the interval between the vastus medialis and rectus femoris muscles proximally to reveal the vastus intermedius muscle.
• Split the vastus intermedius in line with its fibers; directly below lies the femoral shaft covered with periosteum. Continue the dissection in the epiperiosteal plane to get to the bone.

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Approach Extension

Proximal Extension:

• The anteromedial approach to femur can be extended along the same interval between the rectus femoris and vastus medialis muscles.
• To extend the deep dissection, continue to split the vastus intermedius muscle.
• The extension offers excellent exposure of the lower two thirds of the femur.

Distal Extension:

• Continue the skin incision downward, and curve it laterally so that it ends just below the tibial tubercle.
• Incise the medial retinaculum in line with the skin incision, making the patella more mobile and subject to lateral subluxation for full exposure of the knee joint.
• Take care not to avulse the quadriceps tendon from its insertion during the maneuver.

Dangers

The structures at risk during the anteromedial approach to femur include:

1. Medial superior genicular artery:
   • The Medial superior genicular artery crosses field just above knee joint.
2. Vastus medialis muscle:
   • Distal fibers of Vastus medialis muscle insert directly on medial border of patella.
   • It’s disrupted during exposure.
   • Meticulous closure to prevent lateral patella subluxation.

References

• Surgical Exposures in Orthopaedics book – 4th Edition
• Campbel’s Operative Orthopaedics book 12th