Philipp Kobbe and Hans Christoph Pape
DEFINITION
Tibial plateau fractures are intra-articular fractures that may result in a malalignment of the articular surface and bear the risk of subsequent arthritis.
ANATOMY
The tibial plateau consists of three osseous structures: the lateral plateau, the medial plateau, and the intercondylar eminence.
The lateral plateau is smaller and convex, whereas the medial plateau is larger and slightly concave. Both plateaus are covered by a meniscus, which serves as a shock absorber and improves the congruency of the femorotibial joint.
The lateral plateau sits slightly higher than the medial joint surface, forming an angle of 3 degrees of varus with respect of the tibial shaft. This is helpful in identifying the lateral plateau on the lateral radiograph.
The anatomy of the tibial plateau leads to an eccentric load distribution in which the lateral plateau bears 40% of the knee's load.1 This asymmetric weight bearing results in increased medial subchondral bone formation and a stronger, denser medial plateau.
The intermediate, nonarticular intercondylar eminence serves as the tibial attachment of the anterior and posterior cruciate ligaments.
The stability of the knee joint is based on the cruciate ligaments, the collateral ligaments, and the capsule.
The tibial tuberosity and the tubercle of Gerdy are bony prominences located in the subcondylar region for insertion of the patellar tendon and the iliotibial tract, respectively. These landmarks are important for planning surgical incisions.
PATHOGENESIS
Several anatomic factors have been thought to contribute to the higher incidence of lateral as opposed to medial plateau fractures.
The relative softness of the subchondral bone of the lateral plateau, the valgus axis of the lower extremity, and the susceptibility of the leg to a medially directed force all lead to a prevalence of lateral plateau fractures in low-energy injuries.1
Tibial plateau fractures are due to either direct trauma to the proximal tibia and knee joint or to indirect axial forces.
The most frequent mechanism causing a lateral plateau fracture is a direct trauma to the proximal tibia and knee joint. This induces a valgus force and drives the lateral femoral condyle into the soft lateral tibial plateau.
Indirect axial forces often develop in high-energy injuries and may be associated with complex tibial plateau fractures.
Twisting injuries account for only 5% to 10% of tibial plateau fractures and are most commonly sports injuries (eg, skiing).
Split or wedge fractures occur in younger patients, whereas depression fractures occur more frequently in older patients with osteoporotic bone, which is less able to withstand compression.
NATURAL HISTORY
The natural history of lateral tibial plateau fractures depends on the degree of articular depression and knee stability.8 Knee instability may result from the fracture itself but may also result from accompanying injuries like meniscal injuries or rupture of cruciate or collateral ligaments.
For nondisplaced or minimally displaced fractures, the prognosis is favorable,3,5,6,17,19,22 but displaced fractures, especially in combination with knee instability, tend to result in early posttraumatic arthritis.
Meniscal injuries have been reported in up to 50% of tibial plateau fractures. Meniscal injuries are a major determinant of prognosis because meniscal integrity is important for joint stability and may compensate for articular incongruity.
PATIENT HISTORY AND PHYSICAL FINDINGS
The physical examination should always include a thorough assessment of the soft tissue envelope.
The marginal soft tissue envelope of the proximal tibia predisposes to open fractures and development of tissue necrosis. It is important to assess severe soft tissue injury because it may not allow primary plating of the fracture, requiring external fixation.
A compartment syndrome may result from continuous hemorrhage through the metaphysis into the area of the tibial shaft.
Clinical findings indicating a manifest compartment syndrome include pain, paresthesia, paresis, pain with stretch, intact pulses, and pink skin coloring.
Such findings require immediate fasciotomy.
An imminent compartment syndrome requires repeated or continuous compartment pressure monitoring.
A pressure difference between the diastolic pressure and the compartment pressure of less than 30 mm Hg is considered to be a manifest compartment syndrome,15 which requires fasciotomy.
The neurovascular status of the extremity must be carefully evaluated, although concomitant injuries of neurovascular structures are rare in proximal tibia fractures.
Palpation of peripheral pulses
Doppler ultrasound
An ankle-brachial index less than 0.9 indicates that vascular injury is very likely.
Impaired sensorimotor status may indicate compartment syndrome; impaired dorsal flexion may indicate direct peroneal nerve injury.
Examination of knee stability is difficult because of pain, so it should be tested under anesthesia. Assessment of knee stability may be difficult on initial examination because of intracapsular hematoma and pain. Varus and valgus stress radiographs of the knee in near-full extension can be performed with sedation or under general anesthesia. Widening of the femoral–tibial articulation of more than 10 degrees indicates ligamentous insufficiency.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain anteroposterior (AP) and lateral radiographs should be centered on the knee, with the AP view angled 10 degrees in a craniocaudal direction to approximate the posterior slope of the plateau.
The standard tool in analyzing tibial plateau fractures is the three-dimensional CT scan, because the number and degree of isolated fractures are often underestimated on plain radiographs.13
Although MRI evaluates both osseous and soft tissue injuries, it has not yet become a standard tool in analyzing tibial plateau fractures. It may be helpful in identifying meniscal and ligamentous injuries.
In selected cases (eg, no CT diagnostics available), stress radiographs may be helpful in making decisions about surgical management.
DIFFERENTIAL DIAGNOSIS
Ligamentous injuries of the knee
Knee dislocation
Meniscal injury
Bone bruise
Compartment syndrome
NONOPERATIVE MANAGEMENT
For nondisplaced or minimally displaced fractures, the indications for surgical treatment are controversial and vary widely in the literature. The range of acceptance for articular depression varies from 2 mm to 1 cm.3,5,6,17,19,22
Nondisplaced or minimally displaced tibial plateau fractures with stability of the knee joint can be managed nonoperatively, provided that the patient is compliant.
Partial weight bearing in a hinged fracture brace for 8 to 12 weeks with regular radiographic controls is recommended.
Isometric quadriceps exercises and progressive passive, active-assisted, and active range-of-knee motion exercises are recommended to avoid substantial muscle atrophy.
Failure to maintain reduction with nonoperative management is an indication for surgical fracture stabilization. Therefore, frequent surveillance radiographs are required for the management of these patients.
SURGICAL MANAGEMENT
The primary management of tibial plateau fractures is usually dictated by the soft tissue injury and by the fracture type.
Absolute indications for surgery are displaced fractures, open fractures, fractures with vascular or neurologic lesions, fractures with compartment syndrome, and fractures with valgus instability.
The goals in the surgical treatment of tibial plateau fractures are restoration of articular surface, axis, meniscal integrity, and stability to avoid or postpone posttraumatic arthritis. Fracture stability allows early rehabilitation and supports long-term full recovery.
The degree of soft tissue injury and the general condition of the patient are important factors in surgical decision making.
If there is severe soft tissue damage, an open fracture, or a polytraumatized patient, a temporary external fixator is applied. Definitive fracture stabilization with open reduction and internal fixation is delayed until soft tissue damage or the patient's critical condition has been resolved.
Preoperative Planning
Review of radiographs, CT, MRI
Surgical approach and placement of implants
Depression fractures with continuity of the lateral cortex require only screw osteosynthesis.
Whether a cortical window is required depends on the degree and location of impaction. Condylar widening is a good radiologic sign for the requirement of articular elevation with a pestle via a cortical window.
Meniscal and ligamentous injuries require open joint or arthroscopic surgery.
The surgeon should consider the need of bone grafting (iliac crest bone graft, bone graft substitute) when severe depression of the plateau is obvious.
For surgical decision making, a separate classification of the fracture and degree of soft tissue injury is important.
Open fractures are classified according to Gustilo et al.4
The soft tissue injury is classified according to Tscherne and Oestern.21
The AO/OTA classification for proximal tibial fractures distinguishes between extra-articular, partial-articular, and complete-articular fractures, and further subdivides based on the level of comminution (Table 1).
Schatzker's classification distinguishes between lateral and medial plateau fractures (Table 2).
In general, types I through III are low-energy injuries affecting the lateral plateau.
Types IV through VI involve increasingly higher-energy injuries mostly affecting the medial plateau in combination with ligamentous injuries.19
Positioning
Supine position
Bolster under knee to improve internal rotation: the knee should be slightly bent (about 30 degrees) to reduce tension of collateral ligaments (FIG 1)
Tourniquet to minimize blood loss and to improve fracture visualization
Radiolucent operating table to allow intraoperative use of fluoroscopy and image intensification
Contralateral leg placed in leg carrier
Ipsilateral iliac crest is prepared and draped if bone graft is needed.
Approach
The surgical approach for lateral tibial plateau fractures demands good visualization of the lateral plateau, combined with preservation of all anatomic structures and minimal soft tissue and osseous devitalization. It can be summarized as:
Elevation of the meniscus
Reduction of the fracture
Temporary retention with Kirschner wire or small fragment lag screw
Final stabilization with lag screws, conventional plate, or angular stable plate
The incision must be planned to avoid implant location directly underneath the skin incision. Important landmarks are the joint line, the tubercle of Gerdy, the tibial tubercle, the fibula head, and the lateral femoral epicondyle (FIG 2).
The standard approach for lateral tibial plateau fractures is the anterolateral approach, which provides excellent exposure of the lateral plateau and allows good soft tissue coverage of the implant, especially after minimally invasive plate application.
The posterolateral approach is indicated for fractures of the lateral posterior plateau.
FIG 1 • Leg position to reduce collateral ligament tension.
FIG 2 • Landmarks for skin incision.
TECHNIQUES
ANTEROLATERAL APPROACH
A straight or a hockey-stick incision (about 10 cm) with the knee in 30 degrees of flexion is made.
The incision is extended down through the iliotibial band proximally and the fascia of the anterior compartment distally.
The tibialis anterior muscle is elevated off the proximal tibia to the level of the capsule and the coronary ligament is incised (TECH FIG 1).
To expose the lateral tibial plateau, the lateral meniscus is raised with holding sutures after incision of the coronary ligament.
The size of the fragment is crucial for the decision of whether soft tissue is stripped off. For small fragments not allowing compression, stripping the displaced fragment for buttress plating is indicated.
TECH FIG 1 • Anterolateral approach.
POSTEROLATERAL APPROACH
A longitudinal incision is made along the proximal fibula (TECH FIG 2).
The extensor muscles are mobilized from the tibial plateau.
After exposure of the peroneus nerve, osteotomy of fibula head is performed.
At the end of surgery the fibular head is refixated by tension band wiring or screw fixation.
TECH FIG 2 • Posterolateral approach.
REDUCTION
Careful treatment of soft tissue and periosteum is mandatory.
Reduction is aided by ligamentotaxis and careful manipulation. An external fixator or a distractor may be a helpful tool.
Displaced fragments are reduced with reduction tools.
Reduction is temporarily maintained with Kirschner wires or lag screws (TECH FIG 3).
TECH FIG 3 • A. Temporary retention of fracture reduction with Kirschner wire. B. Alignment of angular stable plate. C. Final stabilization with angular stable plate.
REDUCTION OF IMPACTED SEGMENTS
Impression fractures need to be elevated with a pestle, which may be inserted through a distal tibial bone window (TECH FIG 4).
Elevation is achieved by carefully exerting punches on the pestle (eg, with a hammer) under fluoroscopy until the contour of the articular surface is re-established.
In cases of severe bone loss, the defect must be filled with bone graft or bone substitute.
TECH FIG 4 • Use of bone window to reduce articular impaction.
MENISCAL REPAIR
Meniscal integrity is important for stability and to avoid posttraumatic arthritis.
Peripheral longitudinal lesions of the anterior and intermediate part of the meniscus are fixated using the “outside-in suture” technique.
Peripheral longitudinal lesions of the posterior meniscus are fixated using the “all-inside” technique to avoid injury to the neurovascular structures in the popliteal area.
Complex meniscal lesions in the avascular area require resection.
OSTEOSYNTHESIS
Implants
Implants may include cancellous screws, conventional plates, or, most recently, angular stable plates.
If the lateral metaphyseal shell is intact, a lag screw with a washer or a three-hole conventional plate in the antiglide position is usually sufficient.
Multifragmentary fractures or fractures with severe bone loss usually require plate osteosynthesis.
Preformed locking or nonlocking plates allow an exact alignment and retention of the fracture.
A minimally invasive technique by sliding the plate with the aiming device underneath the muscle may be selected. The screws can be applied by stitch incisions.
Locking Plates
In multifragmentary fractures or fractures with severe bone loss, an evidence-based advantage of locking plates versus nonlocking plates has not been reported in the literature.
However, locking plates in these types of plateau fractures are advisable for the following reasons:
Angular stable plates require less bone graft compared to conventional plates in fractures with severe bone loss.
The stability of angular stable plates does not depend on friction between the plate and the bone, so less compression of the periosteum, with consequent better blood supply to the fracture area, is achieved.
Pure Split Fractures of the Lateral Plateau (AO-41-B1 or Schatzker I)
For fixation, two large partially threaded cancellous bone screws with washers can be used (TECH FIG 5).
TECH FIG 5 • Stabilization of B1 or Schatzker I fracture with two lag screws and two-hole plate in antiglide position.
In osteopenic patients a third cancellous bone screw with washer is recommended in an antiglide position; a lateral buttress plate is used in case of fragmentation.
Pure Depression Fractures of the Lateral Plateau (AO-41-B2 or Schatzker III)
The depression is elevated through a cortical window and stabilized with two subchondral cancellous bone screws. In cases of severe bone loss, bone graft or bone graft substitute may also be needed for stabilization.
TECH FIG 6 • Stabilization of B2 or Schatzker III fracture with lag screws and washers. (From Scheerlinck T, Ng CS, Handelberg F, et al. Medium-term results of percutaneous, arthroscopically-assisted osteosynthesis of fractures of the tibial plateau. J Bone Joint Surg Br 1998;80:959–964.)
In osteopenic patients, a third cancellous bone screw with washer is recommended in an antiglide position, whereas in case of fragmentation a lateral buttress plate is used (TECH FIG 6).
Split-Depression Fracture of the Lateral Plateau (AO-41-B3 or Schatzker II)
The depression is elevated by working through the split component and deposition of bone graft (TECH FIG 7).
Three position screws are placed subchondrally to support the impacted joint surface (rafting) and a locking plate or buttress plate is applied.
TECH FIG 7 • Stabilization of B3 or Schatzker II fracture with buttress plate.
POSTOPERATIVE CARE
Rehabilitation must be planned individually and depends on patient age, bone quality, type of osteosynthesis, and concomitant injury.
Ninety degrees of flexion should be achieved by 7 to 10 days.
Toe-touch weight bearing is recommended for 4 to 8 weeks, with progression thereafter according to radiographic findings.
Impression fractures of the lateral plateau managed with a minimally invasive angular plate are allowed weight bearing about 12 weeks after surgery.
Early mobilization and range-of-motion exercises are key to the successful treatment of proximal tibia fractures to avoid later knee stiffness and muscle wasting.
OUTCOMES
The outcome depends mostly on knee stability, joint congruity, meniscal integrity, and correct axis.
A favorable outcome has been reported for surgically treated low-energy tibial plateau fractures.20 For split and split-depression fractures, adequate surgical techniques yield more than 90% good and excellent results.14
However, concomitant injuries of ligaments and menisci can compromise the outcome. Therefore, maintaining menisci and ligamentous stability is important.8
Satisfactory functional results can be obtained in the face of poor radiographic results, however, and may be due to preservation of the meniscus and its ability to bear the load of the lateral compartment.7,10
COMPLICATIONS
Early complication.
The incidence of wound infection appears to correlate with the amount of hardware implanted and ranges from 0% to 32% for fractures managed with the buttress technique.23
Deep vein thrombosis rates are reported to be 5% to 10%, and pulmonary embolus occurs in 1% to 2% of patients.2,12
Late complication.
Loss of fixation with axial malalignment and valgus deformity11,19
Malunion as a consequence of inadequate reduction or loss of reduction9
Posttraumatic arthrosis, which may result from the initial chondral damage or may be related to residual joint incongruity8,18
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