Posterolateral Approach to the Tibia

Posterolateral Approach to the Tibia

The posterolateral approach3 is used to expose the middle two-thirds of the tibia when the skin over the subcutaneous surface is badly scarred or infected. It is a technically demanding operation. The approach is suitable for the following uses:

1. Internal fixation of fractures

2. Treatment of delayed union or nonunion4 of fractures, including bone grafting

3. The approach also permits exposure of the middle of the posterior aspect of the fibula.

 

Position of the Patient

 

Place the patient on his or her side with the affected leg uppermost. Protect the bony prominences of the bottom leg to avoid the development of pressure sores. Exsanguinate the limb by elevating it for 5 minutes, then inflate a tourniquet (Fig. 11-34).

 

Landmark and Incision

Landmark

The lateral border of the gastrocnemius muscle is easy to palpate in the calf.

Incision

Make a longitudinal incision over the lateral border of the gastrocnemius muscle centered over the pathology that is to be treated. The length of the incision depends on the length of bone that must be exposed (Fig. 11-35) but a minimum of 10 cm is needed.

 

 

 

Figure 11-34 Position for the posterolateral approach to the tibia.

Internervous Plane

 

The internervous plane lies between the gastrocnemius, soleus, and flexor hallucis longus muscles (all of which are supplied by the tibial nerve) and the peroneal muscles (which are supplied by the superficial peroneal nerve)—between the superficial and deep posterior and lateral muscular compartments (Fig. 11-36).

 

Superficial Surgical Dissection

 

Reflect the skin flaps, taking care not to damage the short saphenous vein, which runs up the posterolateral aspect of the leg from behind the lateral malleolus. Incise the fascia in line with the incision and find the plane between the lateral head of the gastrocnemius and soleus muscles posteriorly, and the peroneus brevis and longus muscles anteriorly. Muscular branches of the peroneal artery lie with the peroneus brevis in the proximal part of the incision and may have to be ligated (Fig. 11-37).

Find the lateral border of the soleus and retract it with the gastrocnemius medially and posteriorly; underneath, arising from the posterior surface of the fibula, identify the flexor hallucis longus (Fig. 11-38).

 

 

 

Figure 11-35 Incision along the lateral border of the gastrocnemius.

 

 

Figure 11-36 The internervous plane lies between the gastrocnemius, soleus, and flexor hallucis longus muscles (which are supplied by the tibial nerve) and the peroneal muscles (which are supplied by the superficial peroneal nerve).

 

 

 

Figure 11-37 Reflect the skin flaps. Incise the fascia in line with the incision. Find the plane between the lateral head of the gastrocnemius and soleus posteriorly, and the peroneus brevis and longus anteriorly.

 

 

Figure 11-38 Detach the origin of the soleus from the fibula, and retract it posteriorly and medially along with the gastrocnemius. Retract the peroneal muscles anteriorly. Detach the flexor hallucis longus from its origin on the fibula. Develop the plane between the gastrocnemius–soleus group posteriorly and the peroneal muscles anteriorly (cross section). Note the flexor hallucis longus on the posterior surface of the fibula.

 

Deep Surgical Dissection

 

Detach the lower part of the origin of the soleus muscle from the fibula and retract it posteriorly and medially. Detach the flexor hallucis longus muscle from its origin on the fibula and retract it posteriorly and medially (Fig. 11-39; see Fig. 11-38). Continue dissecting medially across the interosseous membrane, detaching those fibers of the tibialis posterior muscle that arise from it. The posterior tibial artery and tibial nerve are posterior to the dissection, separated from it by the bulk of the tibialis posterior and flexor hallucis longus muscles (Fig. 11-40). Follow the interosseous membrane to the lateral border of the tibia, detaching the

muscles that arise from its posterior surface subperiosteally to expose its posterior surface (Fig. 11-41).

 

 

Dang

 

 

Vessels

The small (short) saphenous vein may be damaged when the skin flaps are mobilized. Although the vein should be preserved if possible, it may be ligated, if necessary, without impairing venous return from the leg.

Branches of the peroneal artery cross the intermuscular plane between the gastrocnemius and peroneus brevis muscles. They should be ligated or coagulated to reduce postoperative bleeding.

The posterior tibial artery and tibial nerve are safe as long as the surgical plane of operation remains on the interosseous membrane and does not wander into a plane posterior to the flexor hallucis longus and tibialis posterior muscles.

 

 

 

Figure 11-39 Detach the flexor hallucis longus from its origin on the fibula and retract it posteriorly and medially. Continue dissecting posteriorly, staying on the posterior surface of the fibula. Detach the flexor hallucis longus from its origin on the fibula, staying close to the bone (cross section). Retract the muscle medially.

 

 

 

Figure 11-40 Continue dissecting medially across the interosseous membrane, detaching those fibers of the tibialis posterior that arise from it. Continue dissecting across the membrane until the posterior aspect of the tibia can be seen. Incise the periosteum on the lateral border of the tibia. Continue the dissection posteriorly across the fibula and the interosseous membrane until the lateral border of the tibia is reached (cross section). Note that the neurovascular structures are protected by the bulk of the tibialis posterior.

 

How to Enlarge the Approach

Extensile Measures

 

Proximal Extension. The approach cannot be extended into the proximal fourth of the tibia.

There, the back of the tibia is covered by the popliteus muscle and the more superficial posterior tibial artery and tibial nerve, making safe dissection impossible.

Distal Extension. The approach can be made continuous with the posterolateral approach to the ankle if the skin incision is extended distally between the posterior aspect of the lateral malleolus and the Achilles tendon.

 

 

 

Figure 11-41 Detach the muscles that arise from the posterior surface of the tibia subperiosteally. Expose the posterior border of the tibia subperiosteally (cross section). The detached tibialis posterior muscle protects the neurovascular structures.