Posteromedial Approach to the Tibial Plateau

Positioning

The patient is placed prone on a radiolucent table with the knee flexed 20 to 30 degrees over a bump. This position allows gravity to retract the gastrocnemius and provides direct posterior access. The leg is prepared and draped free. A tourniquet is applied but usually not inflated unless bleeding obscures vision.

Alternative positioning is the floppy lateral position with the affected side up and the knee flexed. This position allows access to both posteromedial and posterolateral columns without repositioning and is useful when combined approaches are anticipated.

Surface Landmarks

• Posteromedial border of the proximal tibia
• Medial head of gastrocnemius
• Pes anserinus insertion on the medial tibia
• Joint line (palpated with knee flexed)
• Fibular head (for orientation of the popliteal fossa)

The incision is planned along the posteromedial border of the proximal tibia, starting 8 to 10 centimetres distal to the joint line and extending proximally to the level of the joint line or slightly beyond if proximal extension is required.

Superficial Internervous Plane

The superficial plane lies between the pes anserinus tendons (sartorius supplied by femoral nerve, gracilis and semitendinosus supplied by obturator nerve) anteriorly and the medial head of gastrocnemius (tibial nerve) posteriorly. All three nerves are branches of different roots of the lumbosacral plexus, making this a true internervous plane.

Deep Internervous Plane

Once the medial gastrocnemius is retracted laterally, the deep plane is between the medial gastrocnemius (tibial nerve) and the soleus origin on the posterior tibia (also tibial nerve). Although both muscles share the same nerve, the plane is safe because the nerve branches enter the muscles proximally and the dissection stays distal to the motor branches.

Key Anatomic Note

The popliteal neurovascular bundle lies immediately posterior to the tibial plateau within the popliteal fossa. The tibial nerve and popliteal artery are at risk during deep retraction. All retractors must be placed under direct vision with gentle force directed away from the bundle.

Incision

A longitudinal incision is made along the posteromedial border of the proximal tibia. The incision begins at the level of the joint line and extends distally 10 to 12 centimetres. The length can be extended proximally or distally as needed.

Subcutaneous Dissection

The saphenous nerve and greater saphenous vein are identified in the subcutaneous fat along the posteromedial border. They are gently retracted anteriorly and protected with vessel loops. The fascia over the pes anserinus and medial gastrocnemius is exposed.

Fascial Incision

The fascia is incised along the anterior border of the medial gastrocnemius. The pes anserinus tendons are identified and retracted anteriorly. The interval between the pes anserinus and the medial gastrocnemius is developed bluntly with scissors or a finger. This plane is relatively bloodless.

Common Pitfall

Failure to identify the saphenous nerve before fascial incision leads to iatrogenic injury. Always palpate and visually confirm the nerve position before incising fascia.

Deep Exposure

The medial head of gastrocnemius is retracted laterally. The soleus origin on the posterior tibia is elevated subperiosteally from medial to lateral. The posterior cortex of the proximal tibia is exposed. The popliteal neurovascular bundle is protected by staying anterior to the gastrocnemius and using only gentle lateral retraction.

Danger Structures by Layer

• Subcutaneous: saphenous nerve and greater saphenous vein - identify early, protect with vessel loop, avoid excessive traction
• Fascial: no major structures, but watch for small perforating vessels
• Deep muscular: popliteal artery, popliteal vein, tibial nerve - gentle retraction only, never place metal retractors directly on the bundle, release retractors every 20 minutes
• Capsular: posterior capsule and posterior horn of medial meniscus - incise carefully under direct vision

At-Risk Structures Summary

The saphenous nerve is the most commonly injured structure in this approach if not identified. The popliteal artery is the most serious - injury can result in limb loss. The tibial nerve injury causes plantarflexion weakness and sensory loss on the sole.

Proximal Extension

The incision can be extended proximally along the medial border of the gastrocnemius to expose more of the posterior femoral condyle if needed for associated injuries. The saphenous nerve must be protected during proximal extension.

Distal Extension

Distal extension follows the posteromedial border of the tibia. The soleus can be further elevated. Care is taken to avoid the posterior tibial artery and tibial nerve as they course distally.

Procedures Performed Through This Approach

• Open reduction and internal fixation of isolated posteromedial tibial plateau fractures
• Buttress plating of posteromedial split or split-depression fragments
• Fixation of posterior coronal plane fractures of the medial plateau
• Combined approaches for bicondylar fractures (with anterolateral approach)
• Revision surgery for posteromedial malunion or nonunion
• Bone grafting of posteromedial metaphyseal defects

Closure

The posterior capsule is closed if opened. The soleus origin is not repaired. The fascia is closed loosely to avoid compartment syndrome. Subcutaneous tissue is closed in layers. Skin is closed with interrupted nylon or staples. A drain is placed if extensive dissection was performed.