Anterior and Posterior Approaches to the Medial Malleolus
The anterior and posterior approaches are used mainly for open reduction and internal fixation of fractures of the medial malleolus.2 The approaches provide excellent visualization of the malleolus.
Position of the Patient
Place the patient supine on the operating table. The natural position of the leg (slight external rotation) exposes the medial malleolus well. Exsanguinate the limb by elevating it for 3 to 5 minutes, then inflate a tourniquet. Standing or sitting at the foot of the table makes it easier to angle drills correctly (Fig. 12-5).
Incisions
Two skin incisions are available.
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The anterior incision offers an excellent view of medial malleolar fractures. It also permits inspection of the anteromedial ankle joint and the anteromedial part of the dome of the talus.
Make a 10-cm longitudinal curved incision on the medial aspect of the ankle, with its midpoint just anterior to the tip of the medial malleolus. Begin proximally, 5 cm above the malleolus and over the middle of the subcutaneous surface of the tibia. Then, cross the anterior third of the medial malleolus, and curve the incision forward to end some 5 cm anterior and distal to the malleolus. The incision should not cross the most prominent portion of the malleolus (Fig. 12-6).
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The posterior incision allows reduction and fixation of medial malleolar fractures and visualization of the posterior margin of the tibia.
Make a 10-cm incision on the medial side of the ankle. Begin 5 cm above the ankle on the posterior border of the tibia, and curve the incision downward, following the posterior border of the medial malleolus. Curve the incision forward below the medial malleolus to end 5 cm distal to the malleolus (see Fig. 12-10).
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Figure 12-5 Position for the approach to the medial malleolus. The leg falls naturally into a few degrees of external rotation to expose the malleolus.
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Figure 12-6 Keep the incision just anterior to the tip of the medial malleolus.
Internervous Plane
No true internervous plane exists in this approach, but the approach is safe because the incision cuts down onto subcutaneous bone.
Superficial Surgical Dissection
Anterior Incision
Gently mobilize the skin flaps, taking care to identify and preserve the long saphenous vein, which lies just anterior to the medial malleolus. Accurately locating the skin incision will make it unnecessary to mobilize the skin flaps extensively. Next to the vein runs the saphenous nerve, two branches of which are bound to the vein. Take care not to damage the
nerve; damage leads to the formation of a neuroma. Because the nerve is small and not easily identified, the best way to preserve it is to preserve the long saphenous vein, a structure that on its own is of little functional significance (Fig. 12-7). Posterior incision mobilize the skin flaps. The saphenous nerve is not in danger (see Fig. 12-11).
Deep Surgical Dissection
In cases of fracture, the periosteum already is breached. Protect as many soft tissue attachments to the bone fragment as possible to preserve its blood supply.
Anterior Incision
Incise the remaining coverings of the medial malleolus longitudinally to expose the fracture site. Make a small incision in the anterior capsule of the ankle joint so that the joint surfaces can be seen after the fracture is reduced (Fig. 12-8). This is especially important in vertical fractures of the medial malleolus where impaction at the joint surface frequently occurs. The superficial fibers of the deltoid ligament run anteriorly and distally downward from the medial malleolus; split them so that wires or screws used in internal fixation can be anchored solidly on bone, with the heads of the screws covered by soft tissue (Fig. 12-9; see Fig. 12-56).
Posterior Incision
Incise the retinaculum behind the medial malleolus longitudinally so that it can be repaired (Figs. 12-10 and 12-11). Take care not to cut the tendon of the tibialis posterior muscle, which runs immediately behind the medial malleolus; the incision into the retinaculum permits anterior retraction of the tibialis posterior tendon. Continue the dissection around the back of the malleolus, retracting the other structures that pass behind the medial malleolus posteriorly to reach the posterior margin (or posterior malleolus) of the tibia. The exposure allows reduction in some fractures of that part of the bone.
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Figure 12-7 Widen the skin flaps. Identify the long saphenous vein and the accompanying saphenous nerve.
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Figure 12-8 Make a small incision in the anterior capsule of the ankle joint to see the articulating surface.
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Figure 12-9 Split fibers of the deltoid ligament to allow for internal fixation of the fractured malleolus.
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Figure 12-10 The posterior incision for the approach to the medial malleolus follows the posterior border of the medial malleolus.
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Figure 12-11 Retract the skin flaps and begin to incise the retinaculum behind the medial malleolus.
Note that, although this approach will allow visualization of most fractures using appropriate reduction forceps, the angle of the approach is such that the displaced fragments cannot be fixed internally from this approach. Separate anterior approaches are required to lag any posterior fragments back. It always is advisable to obtain an intraoperative radiograph showing the displaced fragment fixed temporarily with a Kirschner wire (K-wire) before definitive fixation is inserted. Reduction in these fragments is difficult because of limited exposure, and inaccurate reduction may occur. To improve the view of the posterior malleolus, externally rotate the leg still further (Fig. 12-12; see Figs. 12-55 and 12-56).
Dangers of the Anterior Incision
Nerves
The saphenous nerve, if cut, forms a neuroma and may cause numbness over the medial side of the dorsum of the foot. Preserve the nerve by preserving the long saphenous vein.
Vessels
The long saphenous vein is at risk when the anterior skin flaps are mobilized. Preserve it if possible, so that it can be used as a vascular graft in the future (see Fig. 12-54).
Dangers of the Posterior Incision
All the structures that run behind the medial malleolus (the tibialis posterior muscle, the flexor digitorum longus muscle, the posterior tibial artery and vein, the tibial nerve, and the flexor hallucis longus tendon) are in danger if the deep surgical dissection is not carried out close to bone (see Figs. 12-54 to 12-56).
Leave as much soft tissue attached to fractured malleolar fragments as possible; complete stripping renders fragments avascular.
How to Enlarge the Approach
Extensile Measures
To enlarge both approaches proximally, continue the incision along the subcutaneous surface of the tibia. Subperiosteal dissection exposes the subcutaneous and lateral surfaces of the tibia along its entire length. The exposure can be extended distally to expose the deltoid ligaments and the talocalcaneonavicular joint.
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Figure 12-12 Anteriorly retract the tibialis posterior. Free up and retract the remaining structures around the back of the malleolus posteriorly to expose the posterior aspect of the medial malleolus.
