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never visited LATERAL TIBIAL PLATEAU FRACTURE
Contributed by: Fritsch & Thompson, Radiologist, Diagnostic Radiology of Houston, Texas, USA.
Patient: 34 year old male
History: Fall from 12 foot ladder.
Images:[small]larger

Fig. 1: Lateral Xray Right Knee

Fig. 2: AP Xray Right Knee

Fig. 3: Oblique Xray Right Knee

Fig. 4: Coronal T2 Fat Sat image showing acute fracture line in lateral plateau

Fig. 5: Coronal T1 image showing fracture line in lateral plateau

Fig. 6: Sagittal T1 image showing fracture line in lateral plateau

Fig. 7: Sagittal T1 image showing fracture line in lateral plateau

Fig. 8: Sagittal T1 image showing fracture line in lateral plateau at level of fibula

Fig. 9: Sagittal T1 image showing fracture line in lateral plateau at level of fibula (note fibular fracture line)

Fig. 10: Axial PD Fat Sat image at level of fibular head. Note acute fracture line in lateral plateau.
Findings:
  • Note lateral tibial plateau disruption on xray.
  • Low signal T1 and high signal T2 fracture line in lateral plateau is indicative of an acute fracture on MR imaging.
  • Note associated fracture of proximal fibula.
  • Associated meniscal tears are common.
Diagnosis: Lateral tibial plateau fracture with associated occult fracture of proximal fibula.
Discussion:

Background: Originally termed a bumper or fender fracture, only 25% of tibial plateau fractures result from impact with automobile bumpers. The most common mechanism of injury involves axial loading, such as results from a fall. Other patterns of injury result from laterally directed forces or from a twisting injury. In all cases, force is directed from the femoral condyles onto the medial and lateral portions of the tibial plateau, resulting in fracture. In younger patients, the most common pattern of fracture is splitting, while in older, more osteoporotic patients, depression fractures typically are sustained.

Soft tissue injuries (eg, to cruciate and collateral ligaments) occur in approximately 10% of patients. In particular, medial plateau injuries may result in fracture of the fibular head, which may injure the peroneal nerve or may be associated with popliteal artery occlusion. Patients may present with a knee effusion, pain, and joint stiffness. Finally, although severe fractures often are repaired surgically, both operatively and nonoperatively treated fractures are at risk of developing posttraumatic osteoarthritis as a result of ligamentous injuries with resultant instability as well as articular discongruities, biomechanical alteration of normal compressive forces, and cartilage damage.


Pathophysiology: Varus stresses tend to be less common than valgus stresses due to the inherent valgus carrying angle of the knee and protection by the opposite extremity. Coupled with the fact that the medial plateau of the tibia is stronger than the lateral, fractures of the lateral plateau are much more common than the medial. To injure the medial plateau requires a large amount of force, and fractures of the medial plateau usually are seen in conjunction with fractures of the lateral plateau and other bones about the knee joint, as well as the supporting structures. In particular, forces that result in fractures of the lateral plateau (75-80% of fractures) are directed medially and also may result in disruption of the anterior cruciate ligament or the medial collateral ligament.

Since laterally directed forces that cause medial plateau injuries (5-10% of fractures) tend to be much more violent, additional soft tissue structures tend to be injured, including the posterior cruciate ligament, popliteal artery, or lateral stabilization complex of the knee. Pure axial injuries may result in a blend of these soft tissue injuries. Only 5-10% of proximal tibia fractures involve the simultaneous fracture of the medial and lateral plateaus and may result in a combination of soft tissue injuries, depending on the nature of the complex and the severity of forces required to injure both sides of the tibial plateau.


Frequency:

  • In the US: The incidence of tibial plateau fractures is unknown. Millions of fractures occur in the United States each year. Of these, approximately 1% are estimated to involve the tibial plateau.
  • Internationally: The international incidence of this fracture is unknown. Fractures of the tibial plateau are estimated to comprise approximately 1% of all fractures.
Mortality/Morbidity: Fractures of the tibial plateau commonly occur in conjunction with other injuries resulting from a fall or motor vehicle accident. Isolated fractures of the tibia are not fatal but may be associated with injuries to nearby structures, including the popliteal artery, ligaments, peroneal nerve, soft tissues, and menisci.

The goal of therapy is to reduce the fracture and begin early mobilization. If the patient is immobilized for a lengthy period (>3 wk), the joint will not return to full range of motion. Depression of a tibial plateau that is inadequately corrected results in a varus or valgus deformity and accelerated osteoarthritis. Unappreciated ligamentous injury causes greater than normal stress on the remaining support structures of the joint, malalignment, and the development of premature osteoarthritis.

As a result of bony fragmentation and depression at the tibial plateau, along with forces applied at the time of injury by the femoral condyles, the menisci are prone particularly to injury, and they often detach. Collateral and cruciate ligaments may be damaged by this mechanism as well. Occasionally, the tibial tubercle may avulse.

In particular, fractures of the medial tibial plateau are associated with greater force, more osseous damage, and more injuries to associated knee structures. Dislocation-relocation injuries are more common with medial plateau injuries than with lateral plateau injuries. With this pattern, the peroneal nerve may be sheared, and the intima of the popliteal artery may be disrupted. The latter may thrombose, or a dissection may develop. However, it is uncommon for this intimal injury to result in life-threatening hemorrhage.

Skin injury to the proximal leg is common with tibial plateau fractures. As a result of the superficial location of the cortex of the anterior tibia, loss of skin coverage may result in osteomyelitis or necrosis. The skin may become infected.

Finally, complex injuries to the knee often involve the tibial diaphysis. With extensive injuries, extensive edema and, possibly, hemorrhage are seen within the fascial compartments of the leg. This may result in an acute compartment syndrome, with resultant compounding of the original injury.

Race: Tibial plateau fractures have no racial predilection.

Sex: The frequency of tibial plateau fractures is higher in older women than in older men, because of the greater incidence of osteoporosis in women.

In younger patients, tibial plateau fractures typically affect men due to their greater involvement in high-energy contact sports such as wrestling and boxing.

Age: Fractures of the tibial plateau in older persons are more common than in the general population. Almost 8% of fractures occurring in older persons are estimated to involve the tibial plateau. This is a result of osteoporosis, with resultant depression-type fractures of the tibia becoming more common.

Anatomy: The osseous structures of the knee include the tibia, fibula, patella, and femur. The principal bones involved in tibial plateau fractures are the femur and tibia. The tibia is composed of the medial and lateral tibial plateaus, as well as the intercondylar eminence. Each plateau articulates with its respective femoral condyle via the menisci, which are cartilaginous structures that are applied closely to each osseous surface.

The anterior and posterior cruciate ligaments attach to the anterior and posterior aspects of the intercondylar tibia. The medial plateau generally is believed to be sturdier than the lateral plateau, supporting the clinical observation that medial plateau fractures typically result from the application of more severe forces than required to produce a fracture of the lateral plateau.

Clinical Details: Patients may present with a knee effusion, pain, and joint stiffness. Although severe fractures often are repaired surgically, both operatively and nonoperatively treated fractures are at risk for posttraumatic osteoarthritis as a result of ligamentous injuries with resultant instability (and possibly varus or valgus deformity). The risk of posttraumatic osteoarthritis is greatest in younger patients.

Surgical intervention depends on numerous factors including the overall condition of the patient and associated local or regional injuries. From an orthopedic standpoint, the degree of articular depression and degree of diastasis of the fractured parts are the most crucial elements to be considered when making a decision regarding surgical intervention. As a general rule, 4-5 mm of articular depression and 3-4 mm of diastasis are considered indicators for surgical management.

References:

http://www.emedicine.com/radio/topic698.htm

Case Of the Week: 12/28/2005

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Additional Details:

Case Number: 2750041Last Updated: 03-17-2006
Anatomy: Skeletal System   Pathology: Trauma
Modality: Conventional Radiograph, MRExam Date: 07-01-2005Access Level: Readable by all users
Keywords: tibial plateau, fracture,

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