The anterolateral approach to the lateral tibial plateau offers safe access to the lateral tibial plateau for:
1. Open reduction and internal fixation of fractures of the lateral tibial plateau
2. Bone grafting for delayed union and nonunion of fractures
3. Treatment of osteomyelitis
4. Excision and biopsy of tumors
5. Harvesting of bone graft
The soft tissue covering of the proximal tibia is thin and delicate consisting of skin and underlying fascia only. Soft tissue problems are common in this area and massive swelling or blistering can occur, particularly following high-velocity trauma. Careful assessment of the soft tissues is critical before surgery, and definitive treatment of fractures in this area is frequently delayed to allow swelling to subside and the soft tissues to recover. The anterolateral approach is preferred to a direct anterior approach to the tibia because the skin incised in the anterolateral approach does not directly overlay the bone and because less skin retraction is necessary to access the middle third of the lateral aspect of the lateral tibial plateau.
Place the patient supine on a radiolucent table. Place a firm wedge beneath the knee to flex the joint to approximately 60 degrees (Fig. 11-2). Place a small bag underneath the buttock to correct the normal external rotation of the lower limb. This will ensure that the patella is facing directly anteriorly. Exsanguinate the limb either by elevating it for 3 to 5 minutes or by applying a soft rubber bandage. Then inflate a tourniquet.
Palpate the shaft of the proximal tibia along its anterior border. Identify the position of the lateral joint line of the knee by flexing and extending the joint. Palpate Gerdy tubercle just lateral to the patella tendon. All these landmarks are easily palpable, even in an obese patient.
Make an inverted L-shaped incision. Start approximately 1 to 3 cm distal
to the joint line, staying just lateral to the border of the patella tendon. Curve the incision anteriorly over Gerdy tubercle and then extend it distally, staying about 1 cm lateral to the anterior border of the tibia (Fig. 11-3). The exact length of the incision depends on the pathology to be treated and the implant to be used.
There is no internervous plane in this approach. The dissection is essentially epiperiosteal and does not disturb the nerve supply to the extensor compartment.
Superficial Surgical Dissection 浅层手术分离
Deepen the incision proximally through subcutaneous tissue to expose the lateral aspect of the knee joint capsule. Incise the knee joint capsule transversely just below the lateral meniscus. Take care not to divide the lateral meniscus inadvertently. Below the joint line, deepen the incision through subcutaneous tissue and incise the fascia overlying the tibialis anterior muscle .
Proximally enter the knee joint by dividing the synovium. Carefully detach the lateral meniscus from its soft tissue attachments inferiorly and develop a plane between the undersurface of the lateral meniscus and the underlying tibial plateau. Insert stay sutures to the periphery of the meniscus to facilitate reattachment during closure. Ensure that the anterior attachment of the meniscus remains intact. Detach a sufficient amount of the meniscus to allow adequate visualization of the superior surface of the lateral tibial plateau. Using an elevator inferiorly detach some of the origin of tibialis anterior from the proximal tibia. Try to work in a plane between the periosteum and the muscle.
The deep branch of the peroneal nerve has a variable course. Normally, it lies well posterior to the area of dissection and it should not be injured.
The lateral meniscus has to be detached from some of its soft tissue attachments inferiorly to allow adequate visualization of the articular surface of the tibia. Take care not to completely detach it, preserving anterior and posterior attachments, however. It is at most risk during the incision of the knee joint synovium.
Application of a distractor or external fixator to the lateral aspect of the knee between the femur and the tibia allows a varus distraction force to be applied to the knee joint, thereby opening up the lateral compartment.
Extensile Measures 延伸措施
Proximal Extension. To extend the approach proximally, continue the skin incision along the lateral aspect of the patella, then curve posteriorly over the lateral aspect of the distal femur. Deepen the incision through the lateral joint capsule to gain access to the knee joint and the distal femur proximally.
Distal Extension. To extend the approach distally, continue the incision in a longitudinal fashion, remaining 1 cm lateral to the anterior border of the tibia. Extend it all the way down to the ankle proximally. Deep dissection, either by splitting the tibialis anterior muscle or by detaching it from the lateral aspect of the tibia, allows access to the tibial shaft down to its distal quarter.