Mechanism, Evaluation, and Temporary Fixation

Demographics

Fractures involving the tibial articular surface account for a little over 1% of all long bone fractures, 56.9% of all proximal tibia fractures/dislocations, and 8% of all fractures in the elderly. These fractures have an annual incidence of 10.3 per 100,000. The combined incidence of a patient having a tibial plateau fracture with associated polytrauma on admission has been estimated at 16% to 40%. The age distribution is bimodal for both males and females, which is similar to what is seen in other periarticular injuries. The majority of fractures occur in males (70%), with men aged 40 to 44 years being the most affected patient population overall. ^, Comminuted fractures are more common in males. There is a shift of incidence between males and females that occurs after the age of 60, with females (61%) predominating. ^, With an increase in life expectancy and a large aging population in many developed countries, it is expected that the incidence of low-energy tibial plateau fractures will continue to increase. Medical comorbidities and certain medications can affect bone quality, increase the risk of postoperative infection, and inhibit wound healing.

Mechanism of Injury

The mechanism of tibial plateau fractures varies by the age of the patient. The majority of tibial plateau fractures in the elderly are due to low-energy falls. Osteopenia and osteoporosis play a large role in the fracture mechanisms and patterns observed. The forces acting on bone determine the resulting fracture patterns in conjunction with bone quality. Low bone density decreases the force necessary for injury. In the elderly, lateral fracture patterns are seen more commonly than medial ones. A higher incidence of compression fracture patterns tends to be seen in such cases with lower-energy injury mechanisms. In younger individuals, high-energy mechanisms predominate. The injury mechanism can involve motor vehicles, sports, and falls from height. The most common mechanism of injury overall is pedestrians being struck by motorized vehicles (30%), followed by low-energy falls (22%).

The magnitude and direction of the injury force will often influence the fracture pattern. Angular, axial, and compression forces can all lead to failure of the condyles. Axial load is usually a predominant component of the injury mechanism and produces higher energy at failure than angular forces. In general, greater axial load results in more severe fractures with increased comminution, fragment displacement, and associated soft-tissue injury. In a cadaver study that looked at mechanisms of injury, it was found that pure valgus forces resulted in the typical lateral split fractures, axial forces resulted in joint compression fractures, and a combination of axial and valgus forces resulted in split depression fractures. In isolated lateral plateau fractures, the medial collateral ligament can act as a pivot point causing the lateral femoral condyle to impact the lateral tibial plateau. The proximal tibia is more vulnerable to valgus force because of the 5 to 7 degrees of knee valgus in normal anatomic alignment. In addition, lateral side impacts tend to occur as a common injury mechanism in these fractures.

Initial Emergency Department Evaluation

Evaluation and management of tibial plateau fractures in the emergency department will set the stage for successful patient outcomes. One should suspect a tibial plateau fracture in a patient who presents with pain and tenderness around the knee following an injury. The pain may be localized to the proximal tibia at the fracture site. The patient may present with a visible knee hemarthrosis secondary to an intraarticular fracture. The patient may also report deep pain secondary to a ligamentous or meniscal injury. Evaluation of a suspected tibial plateau fracture begins with a history and physical examination, as described later. The reported mechanism of injury is important to determine, as it helps predict the severity of the injury, the fracture pattern, and the associated injuries. For example, a fall from standing is a low-energy mechanism, and the risk of associated soft tissue, neurovascular injury, or compartment syndrome (CS) is low. However, if the mechanism is of high energy (as seen with motor vehicle accidents, a pedestrian struck, or a fall from height), then a higher degree of vigilance is necessary to detect associated injuries that may require urgent or emergent management. A thorough physical examination results in the diagnosis of associated injuries and helps establish future surgical timing and treatment.

Examination of the soft-tissue envelope will reveal the presence or absence of significant swelling, abrasions, blisters, and open injury. Open fractures require immediate antibiotics as the delay in the initial dose of antibiotic administration markedly increases the risk of infection. Antibiotic coverage is guided by the severity of injury and contamination and typically includes coverage for gram-positive bacteria. If the open fracture injury appears to be of higher severity, prophylaxis against gram-negative organisms is recommended, and in the case of soil contamination, penicillin may be added as well. ^, As previously discussed, a thorough neurovascular examination should be performed. Any neurological deficits should be documented, whether complete or partial. There is a higher incidence of peroneal stretch injuries with medial plateau and higher-energy mechanisms. If there are abnormalities of the distal leg pulses, further evaluation should ensue, including ankle-brachial index (ABI) measurement and possibly additional evaluation with a computed tomography arteriogram (CTA) or vascular consultation. Furthermore, the importance of assessment of the leg compartments cannot be overemphasized. If CS is evident, based either on classic signs and symptoms or on measured compartment pressures, plans should be set in place for urgent fasciotomies. Patients who present with injury following high-energy mechanisms should be strongly considered for close observation for the development of CS.

Radiographs ultimately guide treatment decisions and determine the risks of associated injuries. A CT scan is often necessary to optimally characterize a tibial plateau fracture; however, it should not always be ordered during the emergency department evaluation. When temporary external fixation is planned and fracture comminution and shortening are present, CT scans will provide a better picture of the fracture fragments after the application of an external fixator.