Tibial Plateau Fractures

Etiology

The main mechanism of injury is a varus or valgus load along with or without an axial load. Tibial plateau fractures may be lateral, medial, or bicondylar. Injuries to the lateral part of the tibial plateau are most common and can be a consequence of a direct blow to the lateral aspect of the knee. Injuries to the medial plateau require more force and are sustained from high energy mechanisms including axial load from falling from a height and landing on the feet, motor vehicle collisions, and other sources of direct trauma. With high-energy mechanisms such as these, bicondylar fractures are more common than isolated medial plateau fractures. Tibial plateau fractures as a result of low energy mechanisms are more likely to occur in the elderly, or other populations with the osteoporotic disease.

Epidemiology

Tibial plateau fractures comprise 1% of all fractures. The incidence of tibial plateau fractures is 10.3 per 100,000 people annually[2]. The mean age of patients incurring tibial plateau fractures is 52.6 years.[2] The distribution of tibial plateau fractures is bimodal, with men under the age of 50 more likely to sustain this injury via high energy mechanisms and frequently associated with soft tissue injuries. Whilst women over the age of 70 more likely to have tibial plateau insufficiency fractures secondary to falls.[2] Overall, men more commonly sustain tibial plateau fractures than women.

Pathophysiology

The tibia is the weight-bearing bone of the leg, located medially to the fibula. The proximal part of the bone compromises the distal part of the knee joint. The tibial plateau has two articular surfaces, the medial and lateral tibial condyles, also called the medial and lateral plateaus. The medial tibial condyle bears 60% of the knee’s weight and is a thicker structure. It is concave in shape and located slightly more distally compared to the lateral tibial condyle. The lateral tibial condyle is convex in shape, thinner, weaker, and more proximal than the medial tibial condyle. The intercondylar eminence is a bony structure between the two condyles that serves as an attachment point for the anterior cruciate ligament. Deep fascia separates the lower leg into four compartments containing muscles and neurovascular structures. The anterior, lateral, superficial, and deep posterior compartments border the tibia and are at risk for compartment syndrome with tibial fractures. The ligaments and menisci of the knee joint are also at risk for injury in association with tibial plateau fractures. Lateral meniscal tears are more common in association with Schatzker type II fractures and where there is more than 10 mm of articular surface depression, while medial meniscus tears are most common in Schatzker type IV plateau fractures. Anterior cruciate ligament injuries have been reported in a quarter of Shatzaker type IV and VI fracture patterns. Vascular injuries are commonly seen in Schatzker type IV fracture-dislocations [3], [4]. Vascular injury is also a complication of proximal tibial fractures and Schatzaker type IV tibial plateau fractures. The popliteal artery runs posterior to the knee, and branches into the anterior and posterior tibial artery.

The three-column theory of tibial plateau fractures states that zero-column fracture is a purely articular fracture. Whilst one column fracture is an isolated articular depression with a fracture in the column and two-column fractures are either anteromedial with posteromedial fractures or anterolateral with separate posterolateral depression fractures.

History and Physical

Tibial plateau fractures should be suspected in patients presenting with knee pain, possible deformity, edema, and a suspected mechanism of injury or risk factors that predispose to this type of fracture.

Patients with very high energy mechanisms of injury may present to the trauma bay and undergo complete ATLS evaluation, and prioritization should always be given to evaluating ABCs and stabilizing the patient. A pulseless distal extremity is an orthopedic emergency. Complete physical exam of a potential tibial fracture should include an examination of the entire knee, comparison to the contralateral (presumably uninjured) knee, with special attention to the following:

• Skin: The skin should be examined circumferentially to evaluate for an open fracture, lacerations, or puncture wounds.
• Knee effusion: If there is a significant effusion, the knee may be aspirated to evaluate for hemarthrosis, and for the presence of lipids or bone marrow elements, suggesting intraarticular fracture.
• Neurovascular exam: Sensation, motor function, and distal pulses should be assessed. There should be a low threshold to measure Ankle-brachial indices should there be a difference in pulses between extremities.
• Compartments: All compartments should be palpated; a firm, tense compartment suggests compartment syndrome, which can be further evaluated by measuring intracompartmental pressure.
• Laxity tests: More than 10 degrees of laxity at the joint line with varus/valgus stress testing suggests a tear of the collateral ligaments. Laxity below the joint line is indicative of a displaced fracture.
• The range of motion: Range of motion and strength may be very difficult to assess secondary to pain.

Evaluation

All imaging modalities should be analyzed for the specific pattern, shape, size, and location of the different fragments. Plain radiographs should include anterior-posterior, lateral, and intercondylar notch views. The anteroposterior views may show sclerotic bands suggestive of compression, joint malalignment, or depression of the articular surface. The lateral views can be useful in spotting posteromedial fracture lines. Other additional views can include oblique views and tibial plateau views (10 degrees caudal tilt), which can be helpful in determining the amount of articular surface depression. However, these views are becoming less important in the presence of CT scans. Also, tibial plateau fractures can be difficult to see on plain films, with a sensitivity of 85%.[1] These injuries are associated with significant morbidity, and frequently require operative management, therefore if there is a high degree of suspicion for tibial plateau fractures and negative plain radiographs, a CT scan is indicated. Some radiographic signs have been reported to be associated with injuries to the lateral meniscus, lateral collateral ligament injuries, or posterior cruciate ligament injuries. That includes articular surface depression of more than 6mm and/ or articular widening of more than 5 mm. When depression and widening is more than 8 mm, the medial meniscal injury was frequently reported [5][6] 

CT scan assesses articular surface depression and comminution. Also, it delineates fracture pattern, size of fracture fragment, shape, and location for surgical planning. A lipohemarthrosis is an indication of an occult fracture. CT scan can alter fracture classification and a treatment plan formulated based on the initial radiographs.[7] 

MRI scan would be indicated to evaluate meniscal and ligamentous pathologies.

The knee joint should be evaluated for fracture lines, displacement, depression of the tibial plateau, and associated ligamentous or meniscal injury. 

None of the tibial plateau fracture classification systems are ideal. [8][9] Tibial plateau fractures can be classified based on the Schatzker Classification system, summarized below:

• Schatzker I: Lateral plateau split fracture
• Schatzker II: Lateral plateau split-depressed fracture
• Schatzker III: Lateral plateau pure depression fracture
• Schatzker IV: Medial plateau fracture
• Schatzker V: Bicondylar plateau fracture
• Schatzker VI: Metaphyseal-diaphyseal dissociation

10% of all tibial plateau fractures can not be classified based on Schatzker classification. Especially fractures associated with dislocations or knee instability. Hohl and Moore suggested an alternative classification of tibial plateau fractures as per the following:

• Type I: Coronal split fracture
• Type II: Entire condylar fracture
• Type III: Rim avulsion fracture of the lateral tibial plateau
• Type IV: Rim compression fracture
• Type V: Four-part fracture

Either CT or MRI can better demonstrate the extent of plateau depression and comminution than plain radiographs, and may be helpful in surgical planning should this management be indicated. CT scans are typically faster and easier to obtain in an acute setting. However, MRI can identify meniscal and ligamentous injuries. 

Treatment / Management

The main keys for successful functional outcomes of tibial plateau fractures are the restoration of the axial and rotational alignment of the limb and knee stability.[10] Anatomical reduction and restoration of articular congruity are critical but less important when it comes to functional results. [11] Another crucial aspect is soft tissue management. Initial management involves preventing further soft tissue injury until the fracture is stabilized. This can be achieved by knee immobilization and cryotherapy.[12](A1)

Non-Operative Management

This would be indicated in minimally displaced fractures whether it is a split or depression pattern. These fracture patterns typically occur with low energy mechanisms where there are no associated ligamentous injuries. Also, non-ambulatory patients would be candidates for nonoperative management. Fractures appropriate for non-operative management may be placed in a hinged knee brace, immediate passive range of motion can be started and patients would be advised on non-weight bearing for 6-8 weeks followed by partial weight-bearing for further 6 weeks then full weight-bearing as tolerated. The patient should be re-evaluated weekly with plain radiographs for 3 weeks following injury, and assuming there is no further injury or displacement, may be transitioned to imaging biweekly or every three weeks. The patient should remain in the brace until radiographic healing is complete, which may take up to 12 weeks. Physical therapy may begin at this time, and patients may not regain full function until 16 to 20 weeks or longer. Return to activities requiring prolonged weight bearing and stress such as certain sports should not occur until healing is nearly complete, with the affected extremity demonstrating more than 90% of the strength of the unaffected extremity. [1] [13], [14], [15]. 

Operative Management

Open reduction and internal fixation (ORIF): [11]This is indicated for tibial plateau fractures with significant articular step-off, condylar widening, ligamentous instability, and for Schatzer IV, V, and VI injuries. (A1)

The approach is tailored based on the fracture pattern. A lateral approach with a straight or hockey stick anterolateral incision is commonly performed. Posteromedial incision utilizing the interval between pes anserinus and medial head of gastrocnemius has been described for medial plateau fractures and those with posteromedial extensions. Dual surgical incision medial and lateral is indicated for bicondylar fractures. With posterior approaches reserved for posterior shearing fractures.

Reduction (Direct or indirect): It focuses on restoring articular surface continuity and congruity. Any metaphyseal voids should be filled with bone grafts or cement. Bone grafts could be autogenous, allogenic, or artificial substitutes. Calcium phosphate cement has shown high compressive strengths when utilized to fill out metaphyseal defects.

Internal fixation can be achieved with a variety of constructs either screws alone or plate (locked vs non-locked) with the aim of achieving absolute stability to maintain the articular surface. Isolated screw fixation can be used for simple split fractures or depression fractures that have been elevated percutaneously. Non locked plate in a buttress mode would be ideal for simple fracture patterns in healthy bones. Whilst a fixed angle construct such as a locked plate would be more beneficial in comminuted fracture patterns and poor bone quality with the advantages of less compression of periosteum and soft tissues.  

Postoperatively, a hinged knee brace is applied and advice of an early passive range of motion and non-weight bearing for 6 weeks followed by partial weight-bearing for further 6 weeks then weight-bearing as tolerated.

External fixation with limited open/percutaneous fixation of the articular segment:[11] This is indicated in significantly comminuted fractures or highly contaminated open fractures. The principle is to perform articular surface reduction percutaneously or with mini incisions then, stabilize the reduction with subchondral lag screws or wires. After which an external fixator or a hybrid ring fixator is applied. It allows knee range of motion and decreases soft tissue insult. Patients are allowed weight-bearing after callus formation and the fixator stays for two to four months.  This treatment modality has been reported to be associated with a high malunion rate.(A1)

Staged or Sequential fixation: Bridging external fixation with delayed ORIF: [16] may be performed as a temporizing measure when there is significant soft tissue injury, or if the patient has sustained other serious injuries that require damage control orthopedics.[15] The external fixator is applied by inserting two 4.5 or 5 mm half pins in the middle to the distal femur and the middle to the distal tibia. Then reducing the fracture by axial traction and locking the fixator in slight flexion. Bars should be placed in two planes to allow control over the varus-valgus and flexion-extension forces. The external fixators permit soft tissue resuscitation prior to definitive fixation with the advantages of decreased infection rate and wound healing complications. The main disadvantage of this approach is the residual knee stiffness.

Arthroscopically assisted reduction and internal fixation: This can provide equally satisfactory results to open reduction and internal fixation. Especially in Schatzker I to III fractures.[17][18]

Primary Total Knee Arthroplasty: This could be an option in specific patients with specific fracture patterns.

Differential Diagnosis

Tibial plateau fractures commonly present with knee deformity and effusion.  It is important to evaluate for other possible intra-articular fractures such as the distal femur and tibial spine.  The diagnosis for tibial plateau fractures is made with plain radiographs and CT scan.  Additional soft tissue injuries to the medial and lateral meniscus, ACL, and the collateral ligaments should all be considered [19].  

Prognosis

Many studies have shown that after open reduction internal fixation of any type of tibial plateau fracture is associated with decreased functional outcomes.  However, when evaluating for post-traumatic knee arthritis on plain radiographs, this did not correlate with functional outcome.   Studies have shown that higher energy mechanisms of trauma are associated with poor outcomes [20]. The crucial factor that influences long-term outcomes is the restoration of joint stability. External fixation for significantly comminuted fractures has shown a high malunion rate along with indications for delayed arthroplasty in elderly patients. The worst long-term outcomes were reported where there was associated ligamentous instability, meniscectomy, or alteration of the limb mechanical axis by more than 5 degrees.

Complications

Postoperative infections have been associated with male gender, smoking, lung diseases, bicondylar features, and increased intraoperative time. compartment syndrome can be a devastating complication and the treating physician should have a high level of suspicion for this complication.

Long-term complications of tibial plateau fractures may affect the quality of life [20], [21], [22], [23]. For patients whose jobs require a high degree of mobility, a tibial plateau fracture may significantly delay return to employment [24]. These include the followings:

• Abnormal gait.
• Post-traumatic knee osteoarthritis: This has been associated with meniscectomy, axial malalignment, septic arthritis, and ligamentous instability.
• Post-traumatic ankle osteoarthritis is secondary to an abnormal gait.
• Chronic pain.