Posterior Approach to the Tibial Plateau
Posterior Approach to the Tibial Plateau
The posterior approach provides access to the posterior aspect of proximal tibia without endangering the neurovascular structures of the popliteal fossa.12
Its uses include the following:
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Open reduction and internal fixation of tibial plateau
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Fractures involving the posterior column
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Repair of avulsion fractures of the posterior cruciate ligament
Position of the Patient
Exsanguinate the limb by elevating it for 3 to 5 minutes and apply a tourniquet. Place the patient prone on the operating table and place a bolster beneath the leg from midthigh to ankle. This will allow hyperextension of the knee which is a useful maneuver when reducing posterior column tibial plateau fractures as well as facilitating x-ray imaging when using a C-arm (Fig. 11-17).
Landmarks and Incision
Landmarks
Flex and extend the knee to identify the joint line. Palpate the knee joint from behind identifying the fibular head and the biceps tendon laterally and the posteromedial border of the proximal tibia medially.
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Figure 11-17 Place the patient prone on the operating table with a bolster under the thigh to allow hyperextension of the knee if needed for fracture reduction.
Incision
Begin at the level of the knee joint overlying the biceps tendon. Curve the incision obliquely across the posterior aspect of the knee until the posteromedial border of the tibia is reached. Then extend the incision distally to follow the posteromedial border of the proximal tibia for about 15 cm (Fig. 11-18).
Internervous Plane
The internervous plane lies between the most posterior structure of the pes anserinus—the tendon of semitendinosus supplied by the sciatic nerve and the medial head of the gastrocnemius muscle supplied by the tibial nerve.
Superficial Surgical Dissection
Identify and preserve the long saphenous vein which runs along the posterior border of the semitendinosus muscle. Deepen the incision distally by incising the deep fascia overlying the posteromedial border of the tibia. Identify the tendon of semitendinosus which is the most posterior tendon inserting into the pes anserinus. Identify the medial head of gastrocnemius lying medial to the tendon of semitendinosus (Fig.11-19). Develop a plane between the tendon of semitendinosus and the medial head of the gastrocnemius. More proximally do not incise the deep fascia overlying the popliteal fossa (Fig. 11-20).
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Figure 11-18 Make an inverted L-shaped incision. The horizontal limb follows the posterior aspect of the knee joint. The vertical limb follows the posteromedial border of the proximal tibia.
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Figure 11-19 Develop a plane between the tendon of semitendinosus and the medial head of the gastrocnemius.
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Figure 11-20 Develop a plane between the medial head of gastrocnemius and the tendon of semitendinosus.
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Figure 11-21 Detach the popliteus muscle from the posterior aspect of the proximal tibia staying in a subperiosteal plane.
Deep Surgical Dissection
Retract the medial head of gastrocnemius laterally and identify the posteromedial border of the tibia. The posterior border of the medial collateral ligament may be seen. Retract the pes anserinus medially but do not incise it. The origin of popliteus is seen covering the posteromedial aspect of the proximal tibia. Flex the knee to take tension off the muscle and detach it from the tibia staying in a subperiosteal plane working from medial to lateral (Figs. 11-21 and 11-22).
The whole of the back of the proximal tibia is visualized except the posterolateral corner which is overlain by the fibular head for about 5 cm from the joint line.
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Figure 11-22 The posterior aspect of the proximal tibia is revealed.
Dang
The saphenous vein and saphenous nerve must be identified and preserved during the superficial dissection. The deep dissection must remain on bone beneath the popliteus muscle. Straying anterior to the popliteus will result in contact with the neurovascular contents of the popliteal fossa.
Retractors are needed for retracting the medial gastrocnemius laterally and the contents of the popliteal fossa are again put at risk if this is done too vigorously.
If a retractor is placed between the tibia and fibula the anterior tibial artery is at risk as it passes from posterior to anterior compartment just above the interosseous membrane. This structure dictates the distal limit of the approach—approximately 5 cm (Fig. 11-23).
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Figure 11-23 The anterior tibial artery passes from posterior to anterior through the interosseous membrane some 5 cm below the knee. The artery limits exposure distally.
How to Enlarge the Approach
Local Measures
Retraction of the medial head of the gastrocnemius muscle and the popliteus muscle is the key to adequate visualization of the bone. Be aware however that excess retraction may cause compression of the contents of the popliteal fossa.
Extensile Measures
This approach is often used in conjunction with other approaches such as the anterolateral approach to the proximal but it is not classically extensile. It can be extended distally to expose the posteromedial border of the tibia down to the ankle but this is rarely required. It cannot be extended distally to expose the posterior surface of the tibia because the passage of the anterior tibial artery above the superior border of the interosseous membrane limits distal extension of the approach (see Fig. 11-23).
The approach cannot be extended proximally.