Fixation of Posterior Plateau Fractures via Posterior Approaches

DEFINITION

A direct approach with the patient in a prone position to the posterior aspect of the tibial plateau for reduction and stable fixation of tibial plateau fractures which are hard to visualize from conventional anterolateral or extensile medial approaches. Most applicable to fracture-dislocations of the knee (FIG 1).
The approach to the posterior aspect of the proximal tibia was originally described in the French surgical literature by Cadenat³ in 1933. Later, the approach was further described in the English literature by Darrach⁵ in 1945 and Harmon⁷ in 1945. Kaplan⁹ in 1946 provided an excellent description of the anatomy of the approach, although none of these authors described the use of the posterior approach to the proximal tibia for fracture fixation.

More recently, Lobenhoffer et al¹⁰ in 2004 described a limited posterior approach for tibial plateau fracture fixation that has been popularized by subsequent authors that uses the medial aspect and dissection of the extensile approach for the treatment of posteromedial tibial plateau fractures. This can be combined with anterolateral approach for bicondylar tibial plateau fractures during staged management, but it is hard to perform concurrently with an anterolateral tibial plateau approach. Carlson⁴ added the posterolateral incision and dissection for the treatment of posterior dominant bicondylar fractures.

FIG 1 • A 49-year-old female sustained this tibial plateau fracturedislocation during a motorcycle hill-climbing competition. AP and lateral images of the left knee that demonstrate an intact proximal tibial cortex and impaction of the posteromedial femur which makes this fracture pattern an excellent candidate for a direct posterior approach.

Further modification of the posterolateral approach by adding an osteotomy of the proximal fibula has been described Yu et al¹⁵ to improve exposure to the proximal posterolateral tibial plateau. In some circumstances, the fibular osteotomy comes as part of the fracture and this can be exploited to improve fracture visualization.

ANATOMY

Dissection and approach to the posterior aspect of the proximal tibia is performed primarily through three tissue planes: medial, middle, and lateral, all of which are part of the extensile posterior approach (FIG 2A,B).

The medial tissue plane is bounded superiorly by the semimembranosus muscle, the medial head of the gastrocnemius laterally, and the soleus and popliteus inferiorly. The inferior medial geniculate neurovascular bundle is at risk during this dissection if not disrupted by fracture displacement (FIG 3).

FIG 2 • Classic approach to the posterior aspect of the knee as described by Kaplan. A. The skin incision. Red line demonstrates the lateral incision. Green line demonstrates the medial incision. B. The superficial dissection with the popliteal vein and common peroneal nerve dissected. Arrow on peroneal nerve.

FIG 3 • Posteromedial tibial plateau approach described by Lobenhoffer¹⁰ and popularized by Smith et al. The posteromedial approach offers easy access to the posterior aspect of the medial tibial plateau. Reduction and application of buttress fixation of the medial coronal plane splits in the medial plateau are facilitated by this exposure which is posterior to the hamstring tendons and the medial collateral ligament. Visualization of the concave surface of the medial tibial plateau is difficult. Reduction is provisionally performed via cortical reads, and the reduction of the articular surface is confirmed radiographically.

The middle tissue dissection is bounded medially by the medial head of the gastrocnemius, laterally by the lateral head of the gastrocnemius, and inferiorly by the popliteus muscle. The posterior tibial nerve, artery, and venous drainage are at greatest risk during this approach. The rich venous return coming from the gastrocnemius heads is tedious to dissect during this approach plane (FIG 4).
The lateral dissection is bounded superiorly by the popliteus muscle, medially by the lateral head of gastrocnemius, laterally by the posterior aspect of the fibula and the common peroneal nerve, and inferiorly by the soleus. The common peroneal nerve and popliteal artery and nerve are at risk (FIG 5). Proximal fibular osteotomy can be used to improve exposure (FIG 6).

PATHOGENESIS

Direct posterior approaches to the tibial plateau are indicated for reduction and stabilization of fractures of the posterior aspect of the tibial plateau that can either be isolated to a single condyle or bicondylar in nature.
The posterior fracture of the tibial plateau is most commonly associated with fracture-dislocation injuries of the knee wherein the tibia subluxates anteriorly and the femoral condyles impact the posterior aspect of the proximal tibia. Rotation and degree of knee flexion at the time of injury determine condylar involvement, whereas degree of axial loading drives the amount of joint impaction.
Most common in Moore types 1 and 2 fracture-dislocations of the knee
We see this most commonly in skiers who sustain Schatzker 4 injuries as described by Potocnik et al.¹¹
Occasionally, Schatzker 2 split depression injuries involve the posterior aspect of the lateral tibial plateau and are amenable to a direct posterolateral approach.

NATURAL HISTORY

Most high-energy periarticular injuries are treated in a staged manner wherein the knee is initially stabilized in an external fixator (see Chap. 47), allowing the soft tissue envelope to evolve to the point that swelling is resolving and any fracture blisters have reepithelialized.
The decision to proceed with open reduction and internal fixation can been made once the soft tissue envelope is no longer being actively damaged and has moved past the acute inflammatory phase (generally >5 days).
Healing of metaphyseal fractures generally occurs slowly by creeping substitution and therefore requires prolonged periods of protected weight bearing (10 to 12 weeks).

PATIENT HISTORY AND PHYSICAL FINDINGS

Advanced trauma life support (ATLS) guidelines. Comprehensive physical examination to determine all associated injuries.
Examination of the affected lower leg. Documenting the neurovascular status of the limb. Ankle-brachial indices should be obtained; values less than 0.9 should trigger a vascular consult.
Soft tissue injuries should be documented as well as previous scars.
A high index of suspicion should be maintained for compartment syndrome before and after placement of external fixation, if used.

FIG 4 • Extensile posterior approach to the proximal tibia as described by Trickey¹³ and more recently by Tscherne and Johnson.⁸ Access to the posterior tibial plateau via the extensile posterior approach. Surgical access to the PCL insertion and origin.

FIG 5 • Posterolateral approach to tibial plateau. Posterolateral tibial plateau as seen through the posterolateral approach to the tibial plateau. Note, the position of fibular head tends to obscure much of the view. This approach offers limited access to posterolateral tibial plateau. Improved access can be obtained by a fibular osteotomy.

FIG 6 • With fibular osteotomy. Fibular osteotomy improves the view of the posterolateral plateau.

IMAGING AND OTHER DIAGNOSTIC STUDIES

Orthogonal radiographs of the knee to include anteroposterior (AP) and lateral images.
Contralateral knee orthogonal images: AP and lateral. The author’s preference is to control for subtle anatomic differences between individuals. The contralateral radiographs allow the surgeon to reconstruct the fractured knee in the mirror image of its uninjured partner.

A computed tomography (CT) of the knee is invaluable in determining the exact location of the articular injury to the tibial plateau (FIG 7). This includes the location of the impaction that needs to be elevated. The CT scan should be obtained after spanning external fixation when a staged operative approach is selected. Sagittal and coronal reconstructions may also be helpful.

FIG 7 • Axial CT clearly demonstrates the position of articular impaction of the posterolateral tibial plateau. Direct visualization and reduction of the articular surface is possible via a posterolateral approach.

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