Lateral Tibial Plateau Fractures
Philipp Kobbe
Hans Christoph Pape
DEFINITION
Tibial plateau fractures are intra-articular fractures that may result in a malalignment of the articular surface and bear the risk of subsequent arthritis.
ANATOMY
The tibial plateau consists of three osseous structures: the lateral plateau, the medial plateau, and the intercondylar eminence.
The lateral plateau is smaller and convex, whereas the medial plateau is larger and slightly concave. Both plateaus are covered by a meniscus, which serves as a shock absorber and improves the congruency of the femorotibial joint.
The lateral plateau sits slightly higher than the medial joint surface, forming an angle of 3 degrees of varus with respect of the tibial shaft. This is helpful in identifying the lateral plateau on the lateral radiograph.
The anatomy of the tibial plateau leads to an eccentric load distribution in which the lateral plateau bears 40% of the knee’s load.1 This asymmetric weight bearing results in increased medial subchondral bone formation and a stronger, denser medial plateau.
The intermediate, nonarticular intercondylar eminence serves as the tibial attachment of the anterior and posterior cruciate ligaments.
The stability of the knee joint is based on the cruciate ligaments, the collateral ligaments, and the capsule.
The tibial tuberosity and the tubercle of Gerdy are bony prominences located in the subcondylar region for insertion of the patellar tendon and the iliotibial tract, respectively. These landmarks are important for planning surgical incisions.
PATHOGENESIS
Several anatomic factors have been thought to contribute to the higher incidence of lateral as opposed to medial plateau fractures.
The relative softness of the subchondral bone of the lateral plateau, the valgus axis of the lower extremity, and the susceptibility of the leg to a medially directed force all lead to a prevalence of lateral plateau fractures in lowenergy injuries.1
Tibial plateau fractures are due to either direct trauma to the proximal tibia and knee joint or to indirect axial forces.
The most frequent mechanism causing a lateral plateau fracture is a direct trauma to the proximal tibia and knee joint. This induces a valgus force and drives the lateral femoral condyle into the soft lateral tibial plateau.
Indirect axial forces often develop in high-energy injuries and may be associated with complex tibial plateau fractures.
Twisting injuries account for only 5% to 10% of tibial plateau fractures and are most commonly sports injuries (eg, skiing).
Split or wedge fractures occur in younger patients, whereas depression fractures occur more frequently in older patients with osteoporotic bone, which is less able to withstand compression.
NATURAL HISTORY
The natural history of lateral tibial plateau fractures depends on the degree of articular depression and knee stability.7 Knee instability may result from the fracture itself but may also result from accompanying injuries such as meniscal injuries or rupture of cruciate or collateral ligaments.
For nondisplaced or minimally displaced fractures, the prognosis is favorable,3, 5, 6, 18, 20, 23 but displaced fractures, especially in combination with knee instability, tend to result in early posttraumatic arthritis.
Meniscal injuries have been reported in up to 50% of tibial plateau fractures. Meniscal injuries are a major determinant of prognosis because meniscal integrity is important for joint stability and may compensate for articular incongruity.
PATIENT HISTORY AND PHYSICAL FINDINGS
The physical examination should always include a thorough assessment of the soft tissue envelope.
The marginal soft tissue envelope of the proximal tibia predisposes to open fractures and development of tissue necrosis. It is important to assess severe soft tissue injury because it may not allow primary plating of the fracture, requiring external fixation.
A compartment syndrome may result from continuous hemorrhage through the metaphysis into the area of the tibial shaft.
Clinical findings indicating a manifest compartment syndrome include pain, paresthesia, paresis, pain with stretch, intact pulses, and pink skin coloring.
Such findings require immediate fasciotomy.
An imminent compartment syndrome requires repeated or continuous compartment pressure monitoring.
A pressure difference between the diastolic pressure and the compartment pressure of less than 30 mm Hg is considered to be a manifest compartment syndrome,15 which requires fasciotomy.
The neurovascular status of the extremity must be carefully evaluated, although concomitant injuries of neurovascular structures are rare in proximal tibia fractures.
Palpation of peripheral pulses
Doppler ultrasound
An ankle-brachial index less than 0.9 indicates that vascular injury is very likely.
Impaired sensorimotor status may indicate compartment syndrome; impaired dorsal flexion may indicate direct peroneal nerve injury.
Examination of knee stability is difficult because of pain, so it should be tested under anesthesia. Assessment of knee stability may be difficult on initial examination because of intracapsular hematoma and pain. Varus and valgus stress radiographs of the knee in near-full extension can be performed with sedation or under general anesthesia. Widening of the femoral-tibial articulation of more than 10 degrees indicates ligamentous insufficiency.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain anteroposterior (AP) and lateral radiographs should be centered on the knee, with the AP view angled 10 degrees in a craniocaudal direction to approximate the posterior slope of the plateau.
The standard tool in analyzing tibial plateau fractures is the three-dimensional computed tomography (CT) scan because the number and degree of isolated fractures are often underestimated on plain radiographs.13
Although magnetic resonance imaging (MRI) evaluates both osseous and soft tissue injuries, it has not yet become a standard tool in analyzing tibial plateau fractures. It may be helpful in identifying meniscal and ligamentous injuries.
In selected cases (eg, no CT diagnostics available), stress radiographs may be helpful in making decisions about surgical management.
DIFFERENTIAL DIAGNOSIS
Ligamentous injuries of the knee
Knee dislocation
Meniscal injury
Bone bruise
Compartment syndrome
NONOPERATIVE MANAGEMENT
For nondisplaced or minimally displaced fractures, the indications for surgical treatment are controversial and vary widely in the literature. The range of acceptance for articular depression varies from 2 mm to 1 cm.3, 5, 6, 18, 20, 23
Nondisplaced or minimally displaced tibial plateau fractures with stability of the knee joint can be managed nonoperatively, provided that the patient is compliant.
Partial weight bearing in a hinged fracture brace for 8 to 12 weeks with regular radiographic controls is recommended.
Isometric quadriceps exercises and progressive passive, active-assisted, and active range-of-knee motion exercises are recommended to avoid substantial muscle atrophy.
Failure to maintain reduction with nonoperative management is an indication for surgical fracture stabilization. Therefore, frequent surveillance radiographs are required for the management of these patients.
SURGICAL MANAGEMENT
The primary management of tibial plateau fractures is usually dictated by the soft tissue injury and by the fracture type.
Absolute indications for surgery are displaced fractures, open fractures, fractures with vascular or neurologic lesions, fractures with compartment syndrome, and fractures with valgus instability.
The goals in the surgical treatment of tibial plateau fractures are restoration of articular surface, axis, meniscal integrity, and stability to avoid or postpone posttraumatic arthritis. Fracture stability allows early rehabilitation and supports long-term full recovery.16
The degree of soft tissue injury and the general condition of the patient are important factors in surgical decision making.
If there is severe soft tissue damage, an open fracture, or a polytraumatized patient, a temporary external fixator is applied. Definitive fracture stabilization with open reduction and internal fixation is delayed until soft tissue damage or the patient’s critical condition has been resolved.
Preoperative Planning
Review of radiographs, CT, MRI
Surgical approach and placement of implants
Depression fractures with continuity of the lateral cortex require only screw osteosynthesis.
Whether a cortical window is required depends on the degree and location of impaction. Condylar widening is a good radiologic sign for the requirement of articular elevation with a pestle via a cortical window.
Meniscal and ligamentous injuries require open joint or arthroscopic surgery.
The surgeon should consider the need of bone grafting (iliac crest bone graft, bone graft substitute) when severe depression of the plateau is obvious.
For surgical decision making, a separate classification of the fracture and degree of soft tissue injury is important.
Open fractures are classified according to Gustilo et al.4
The soft tissue injury is classified according to Tscherne and Oestern.22
The AO Orthopaedic Trauma Association (AO/OTA) classification for proximal tibial fractures distinguishes between extra-articular, partial articular, and complete articular fractures, and further subdivides based on the level of comminution (Table 1).
