Wiler, Jennifer L. MD, MBA
Tibial plateau fractures were originally termed “fender” or “bumper” fractures because vehicle-pedestrian collisions can result in this injury pattern. Only 25 percent of tibial plateau fractures result from impact with automobile bumpers. In adults, these injuries result from motor vehicle crashes that cause the knee to be jammed against the dashboard and from contact sports by hyperextension or twisting with laterally directed force. In the osteoporotic elderly, significant direct trauma, knee hyperextension injuries, and a twisting mechanism from a fall are among the most common ways that proximal tibial fractures occur. (Fracture Management for Primary Care. Saunders: Philadelphia, PA. 2003, p. 263.)
The bony structure of the knee includes the tibia, fibula, patella, and femur. The tibia is made up of the medial and lateral tibial plateaus, as well as the intercondylar eminence which anchors the anterior cruciate ligament. Each plateau articulates with a femoral condyle via the cartilaginous menisci.
In all cases of tibial plateau fractures, the force is directed from the femoral condyles onto the medial or lateral portions of the tibial plateau, resulting in fracture. Valgus stresses tend to be far more common then varus stresses, and the medial plateau of the tibia is stronger and thicker than the lateral so lateral plateau fractures are the most common type of plateau fracture (75%). (UCSD Department of Radiology; www.gentili.net/fracture.asp?ID=9.) Forces that result in fractures of the lateral plateau are directed medially, and also may result in disruption of the anterior cruciate ligament or the medial collateral ligament.
Fractures of the medial plateau tend to be associated with a greater force and result in more osseus and soft tissue damage. As a result, they are often coupled with a lateral plateau fracture (25%) and can include injury to other knee supporting soft tissue structures (approximately 10% of patients), including partial or complete ligamentous ruptures (15% to 45%; Wheeless' Textbook of Orthopaedics; www.wheelessonline.com/ortho/tibial_plateau_fractures), popliteal artery, fibular head fracture, peroneal nerve, or lateral stabilization complex of the knee. This is particularly true if the medial plateau fracture is associated with a dislocation-relocation injury mechanism.
Complex knee injuries often involve the tibial diaphysis. With extensive injuries and subsequent severe edema, hemorrhage within the fascial compartments of the leg is possible, resulting in a limb-threatening acute compartment syndrome. Bony fragmentation and depression at the tibial plateau can result in injury or detachment of the menisci (5%-37% of cases) (Wheeless' Textbook of Orthopaedics; www.wheelessonline.com/ortho/tibial_plateau_fractures) and occasionally avulsion of the tibial tubercle. Damage to the overlying skin of the proximal knee is common with plateau fractures because of the superficial location of the anterior tibial cortex. This violation of skin may result in osteomyelitis, cellulitis, or necrosis.
Closed tibial fractures are common long bone fractures. More than 70,000 hospitalizations, 800,000 office visits, and 500,000 hospital days have been attributed to tibial shaft fractures alone. Almost eight percent of fractures occurring in older persons are estimated to involve the tibial plateau. While the elderly suffer many of these fractures from falls, the presence of significant osteoporosis increases the risk for compound or more complex fractures with higher morbidity. (Instr Course Lect 2003;52:607.)
In children, injuries of the proximal tibial epiphysis are rare, accounting for only 35 (3%) of 1025 epiphyseal injuries of the lower extremity in one review series. (J Bone Joint Surg [American Vol.] 1994;76:1870.) Salter-Harris type-II fractures are the most common proximal tibial epiphyseal injuries. In the same review, these accounted for 43 percent of plateau injuries, 15 percent of type I, 22 percent of type III, and 17 percent of type IV. Salter-Harris type-V injuries are rare, accounting for two percent of fractures. (J Bone Joint Surg 1994;76:1870.)
Patients with plateau fractures may present with knee effusion, localized swelling, and bone tenderness. Pain and joint stiffness may limit the examination. Instillation of local anesthetic into the knee joint may facilitate evaluation. Aspiration of fluid often reveals hemarthrosis. The presences of lipid droplets or cellular bone marrow elements indicate an intraarticular fracture. These procedures are not routinely required in the ED evaluation, however. If ligamentous disruption has occurred, the patient may have laxity with provocative testing of the knee. Careful skin inspection is important to identify any wounds or lacerations associated with an open fracture.
It is important to identify any symptoms of acute compartment syndrome in the leg that may result from compromised distal perfusion, including tense swelling, muscle weakness, decreased distal pulses, increased pain elicited by passive stretching of involved muscles, and impaired sensation. If increased compartment pressures are found, then an emergency fasciotomy is indicated.
Standard radiographs for suspected proximal tibial fracture include anterior-posterior, lateral, and intercondylar notch or oblique views. In more subtle injuries, radiographs may appear normal or demonstrate only a slight increase in bone density on the AP view. If there is a high index of clinical suspicion for a tibial plateau fracture in equivocal radiographs, some clinicians would proceed to MRI because it allows for visualization of bony, meniscal, and ligamentous knee injuries. CT scan is an appropriate alternative to MRI, but does not allow for evaluation of meniscal or ligamentous injuries. It does, however, help to characterize further the fractures, quantify tibial depression, and determine the degree of diastasis (splitting) of the fractured parts, all which help orthopedists plan for operative repair. (J Orthop Trauma 1997;11:484.) If popliteal artery injury is suspected, arteriography should be performed emergently.
Many systems have been developed to classify tibial plateau fractures. The Schatzker classification is best known, and includes depression, split, split depression, and condylar subtypes. (UCSD Department of Radiology; www.gentili.net/fracture.asp?ID=9.)
For patients with injuries that are not life- or limb-threatening, ED management of tibial plateau fractures should include compression with knee splinting in full extension, ice, elevation, and strict non-weight bearing. Fractures with significant displacement, depression, or suspected or documented meniscal or ligamentous injury merit orthopedic consultation within 48 hours. Patients with vascular injury or compartment syndrome require emergent orthopedic consultation.
Surgical intervention depends on numerous factors including the patient's overall condition and associated local or regional injuries. In general, the degree of articular depression and diastasis of the fractured parts are the most crucial elements in decision-making. In general, strict non-weight bearing lasts for six weeks, with partial weight bearing allowed in a hing-brace once adequate radiographic healing is identified. (J Bone Joint Surg 2006;88:141.) Typically patients regain full function in less than 12 weeks but often require 16 to 20 weeks.
So far a predictive link between injury severity and outcome has been difficult. (Clin Orthop Relat Res 2004;:85.) Fractures treated operatively and nonoperatively are at risk of developing posttraumatic osteoarthritis with resultant instability as well as cartilage damage. In children, most common complications are angular deformity and limb-length discrepancy. (J Bone Joint Surg 1994;76:1870.)
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