Tibial Plateau fractures make up 1% of all fractures and their occurrence is increased in the elderly. The majority of fractures, up to 70%, are isolated to the lateral plateau. Isolated medial and bicondylar fractures make up the remainder of tibial plateau fractures and are far less common.
The tibial plateau makes up the superior articular surface of the tibia. The tibial plateau is separated medially and laterally by the intercondylar eminence and both surfaces are covered by articular cartilage. The medial plateau is larger, concave and significantly stronger then the lateral plateau. The lateral plateau is smaller, relatively convex and weaker than the medial aspect. The menisci provide some stability and congruence for articulation with the femoral condyles.
The tibia bears 85% of the weight load for the lower extremity. There are 3 attachment sites just distal to the medial and lateral plateau where the muscles of the thigh attach. Medially, the pes anserinus serves as the attachment point for the sartorius, gracilis, and semitendinosus. Laterally, Gerdy tubercle is the insertion point for the iliotibial band. Anteriorly, the tibial tubercle is the attachment point for the patellar ligament. In addition, major ligamentous attachements (MCL, LCL-PLC, ACL, PCL) may be affected by plateau injuries and need to be assessed and addressed. The neurovascular structures that are important are the peroneal nerve laterally and the popliteal vessels and tibial nerve posteriorly.
Mechanism of Injury
The mechanism of injury most commonly associated is a valgus or varus stress coupled with an axial load. The majority of these fractures result from falls or mild lateral impact injuries in the osteoporotic and the elderly. These fractures in a younger population are usually associated with MVCs.
The classification most commonly used is the Schatzker Classification.
Type 1 - lateral fracture split
Type 2 - lateral fracture that is split and depressed
Type 3 - lateral depressed fracture
Type 4 - any medial plateau fracture
Type 5 - bicondylar
Type 6 - fracture that demonstrates separation of the metaphysis from the diaphysis
The OA/OTA classification is also useful for description and research purposes.
Patients with tibial plateau fractures most often present with a knee effusion, soft tissue swelling and are unable to bear weight. The importance of the neurovascular examination should be stressed because of the close proximity to multiple neurovascular structures. Medial plateau injuries are associated with neurovascular complications more frequently due to the increased force required to cause the injury. One must also have a high suspicion for compartment syndrome and ligament injury and have high vigilence for open injuries.
AP and lateral x-rays are mandatory. Oblique views may be helpful if the AP/lateral is negative but bony injury is clinically suspected. A minimally displaced fracture may appear as a mere cortical irregularity on plain radiographs. It also may be warranted to get a 10 degree caudally tilted plateau view to evaluate depression. CT scans have been shown to substantially change the operative plan when compared to using radiographs alone. Although CTs are not always critical they have become important elements of treatment in most injuries. 3-D CT reconstructions can also be helpful in pre-operative planning although their ultimate utility in impacting care has yet to be determined.
Differential Diagnosis/Associated Injuries
Tibial plateau fractures can be associated with meniscal tears and ligament injuries. Again, there is risk for neurovascular injury as was discussed in the physical exam section.
Nonoperative treatment can be chosen for nondisplaced or minimally displaced fractures as well as patients not well enough to undergo a surgical procedure. These patients should initially be immobilized and non weight-bearing. If the fractures proves stable over time, the patient may be transitioned to a hinged knee brace with a gradual increase in motion. The patient should remain non weight-bearing for the majority of 12 weeks to prevent displacement.
Surgery is recommended based on the severity of depression as well as the stability of the knee. That said, the literature does not support the need for surgery based on articular depression alone. In the longest and largest followup series of patients, depression of greater than 10mm, a centrally located defect and instability on follup examination were the greatest predictors of knee arthrosis and poor long-term outcomes. That is not to say that depressions of several mm's are necessarily well tolerated. In the absence of such data, gaps or step-offs of several mm's in the young would, therefore, be best treated with anatomic reduction.
Presence of substantial swelling is an indication to delay surgery. One should consider any type of surgery only after swelling has considerably reduced (could be 7 - 10 days) as evidenced by the appearance of wrinkles. In the presence of significant injury, patients should be temporized with a knee-spanning external fixator (or in mild cases with a brace or splint).
The primary goal of surgery is to restore the joint surface and then reestablish tibial length, alignment and rotation. If there is soft tissue injury including ligamentous or meniscal injury they may also be repaired (although the timing of such repair is still controvertial).
The current standard for surgical repair is open reduction and internal fixation. Preoperative planning should consider stabilization of the lateral plateau, the medial plateau, bony eminence injury and the extensor mechanism. The typical lateral patterns of split and split depression are best approached via a anterolateral incision using the Gerdy's tubercle as the landmark and fixation with an appropriate device. If the medial side is intact, a non-locking plate is almost always sufficient. If there is significant comminution or extention to the medial side, a fixed-angle device may be desired: a plate with locked fixed-angle screws. The medial fracture component often has a postero-medial obliquity that is best treated with a medial exposure and postero-medial buttress plating. A separated tibial spine functionally is an ACL injury and may be addressed with bony fixation. Finally, significant comminution crossing the midline may create a separate tibial tubercle piece which functionally creates an extensor mechanism injury and, similarly, may require distinct fixation.
A limited-incision or percutaneous technique may be used in certain circumstances--one, in patients not medially suitable for extensive surgery and two, simple lateral split injuries (confirmed via CT scan) with no displacement or in which closed reduction can be achieved.
When there is a significant depression component to the lateral plateau, a submeniscal approach (whereby the meniscus is detached from the bony plateau) is advisable. This allows direct visualization of the meniscus (for repair is needed and chosen) and of the cartilaginous plateau surface. The depression can be reduced either through a cortical window or through the fracture split itself. These depression injuries, even when well reduced, often subside in the post-operative period. Therefore, supporting the underlying metaphysis with a graft of choice and protection afterwards to valgus stress becomes important for good radiographic outcomes.
It has also been suggested that arthroscopy can help to determine the extent of injury and thus repairs needed, but this has been a debated topic.
In some cases, external fixation may be used as definitive treatment. A knee-spanning fixator, however, will not allow for motion at the knee and skinny-wire ring fixators (or hybrids), although allowing for motion have increased risk of infection, increased need for time and resources for successful management and are poorly tolerated as opposed to internal fixation. In cases of severe soft tissue injury, established contamination or infection, they may be the treatment of choice.
Some loss of knee motion can be expected. Discomfort from anterolateral hardware (adjacent to Gerdy's-IT band) is also not unusual. While radiographic arthrosis is common, significant clinical arthrosis is not and the conversion rate to total knee replacement is typically reported to be in the single digits.
As discussed previously, neurovascular injury is an increased risk because of the close proximity of the structures. As with all surgical fixations one must inform patients of the risk of malunion, nonunion, and infection.