Lateral Approach to Knee Joint

Lateral Approach to Knee Joint indications:

The lateral approach to knee joint provides access to all the supporting structures on the lateral side of the knee.

Lateral Approach to Knee Joint can be used for:

1. Exposure for lateral knee ligament repair or reconstruction.
2. Open lateral meniscal tear repair.

Read Also:
1. Knee Meniscus Tear
2. Meniscus of the Knee

Position of the Patient

• Place the patient supine on the operating table with a sandbag under the buttock of the affected side. This
  position rotates the leg medially to expose better the lateral aspect of the knee. Flex the knee to 90.

Landmarks and Incision

• Landmarks:
  • Lateral border of patella.
  • Gerdy’s tubercle, insertion of ilio-tibial band.
• Incision:
  • A long, curved incision is needed for adequate exposure of all the lateral structures of the knee.
  • Begin the incision at the level of the middle of the patella and 3 cm lateral to it.
  • With the knee still flexed, extend the cut downward, over Gerdy’s tubercle on the tibia and 4 to 5 cm distal to the joint line.
  • Complete the incision by curving its upper end to follow the line of the femur

Internervous plane

Internervous in Lateral Approach to Knee Joint lies between:

1. Iliotibial band (ITB):  it is the fascial aponeurosis of two muscles, the gluteus maximus and the tensor fasciae latae, both of which are supplied by the superior gluteal nerve.
2. Biceps femoris tendon: it’s innervated by the sciatic nerve.

Although the iliotibial band itself has no nerve supply the plane between it and the biceps femoris can be considered an internervous one because of the band’s muscular origin.

Superficial dissection

• Mobilize the skin flaps widely, underneath are two major structures: the iliotibial band, sweeping down to attach to the anterolateral border of the tibia and Gerdy’s tubercle, and the biceps femoris muscle, passing downward and forward to attach to the head of the fibula. Both these structures may be avulsed from their insertions during severe inward stress to the knee.
• Incise the fascia in the interval between the iliotibial band and the biceps femoris muscle, avoiding the common peroneal nerve on the posterior border of the biceps tendon.
• Retract the iliotibial band anteriorly and the biceps femoris muscle (with the peroneal nerve) posteriorly, uncovering the superficial lateral ligament (fibular collateral ligament) as it runs from the lateral epicondyle of the femur to the head of the fibula. The posterolateral corner of the knee capsule also is visible.

• 

Deep dissection

Enter the joint either in front of or behind the superficial lateral ligament.

Anterior Arthrotomy

• To inspect the entire lateral meniscus, incise the capsule in front of the ligament.
• Make a separate fascial incision to create a lateral parapatellar approach.
• To avoid incising the meniscus, begin the arthrotomy 2 cm above the joint line.

Posterior Arthrotomy

• To inspect the posterior horn of the lateral meniscus, find the lateral head of the gastrocnemius muscle at its origin at the back of the lateral condyle of the femur.
• Dissect between it and the posterolateral corner of the joint capsule. The lateral superior genicular arteries are in this area; they must be ligated or coagulated.
• In cases of trauma, the dissection in this area already may have been done. Make a longitudinal incision in the capsule, starting the arthrotomy well above the joint line to avoid damaging the meniscus or the tendon of the popliteus.
• An arthrotomy of the posterior half of the joint capsule must be performed carefully to avoid damaging the popliteus tendon, which lies outside the meniscus.
• The arthrotomy allows inspection of the posterior half of the lateral compartment behind the superficial lateral ligament.

• 

Approach Extension

• Lateral approach to knee joint cannot be extended usefully.

Dangers

The structures at risk during Lateral Approach to Knee Joint  include:

1. Common peroneal nerve: It’s at risk on posterior border of biceps femoris.
2. Popliteal artery: It’s at risk posterior to posterior horn of lateral meniscus.
3. Popliteus tendon: it runs within joint adjacent to lateral meniscus and attaches to posterior aspect of meniscus and femur. It’s at risk if performing a posterior arthrotomy.
4. Lateral superior genicular artery: It’s at risk between femur and vastus lateralis.
5. Lateral inferior genicular artery: It’s at risk between lateral head of gastrocnemius and posterolateral corner and it should be ligated.

References

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