Internal Fixation of Tibial Plateau Fractures
Fixation constructs depend largely on fracture patterns and on patient factors such as associated injuries and functional status. Classification systems discussed in Chapter 2 can aid in the determination of definitive treatment for tibial plateau fractures. Many commercially available plating systems specific to the tibial plateau are available, with innovations constantly being brought to market. These provide treatment options with precontoured plates that can help secure stable fixation of difficult fracture patterns. Successful operative treatment in tibial plateau fractures begins with gaining the exposure needed to perform reduction and apply fixation (as detailed in Chapter 1 ). Visualization of the plateau may be obtained with fluoroscopy or arthroscopy, with minimal incisions, or with large and/or multiple incisions. It is imperative that the surgeon determines what approach can be used to reduce and adequately stabilize the fracture pattern while exposing the patient to the minimum amount of risk needed to reach those objectives. While it is recommended to perform biologically friendly fixation to the greatest degree possible, it is equally important to recognize when greater exposure is needed in order to achieve reduction and fixation goals.
Indications
Indications for the surgical treatment of tibial plateau fractures are determined primarily by fracture characteristics, such as fracture displacement and instability. These fractures involve the articular surface in the knee joint and such articular displacement leads to alterations in force transmission across the joint and accelerated degenerative changes. Articular displacement/step-off of 3 mm or more is generally cited as an indication for operative treatment. In highly active and younger patients, however, consideration may be given to reduction and fixation with any articular step-off of 1 mm or more.
Additionally, fractures that cause varus or valgus instability meet indications for operative treatment due to the risk of fracture healing with mechanical axis deformity of the tibia. Instability may be detectable by plain radiographs showing displacement on static films or alternatively determined by stress views. Examination under anesthesia in the operating room with fluoroscopy assistance can be performed if questions remain regarding fracture stability. Varus or valgus deformity of greater than 5 to 10 degrees with stress indicates instability. Metaphyseal comminution, bicondylar tibial plateau involvement, and medial tibial plateau fractures are all fracture characteristics that are often indicative of instability.
Articular surface gapping of 3 to 5 mm or more is another common indication for surgical management. This is often determined by tibial condylar widening, which can be measured by comparing contralateral tibia x-rays and/or by comparing tibial condylar width with femoral condylar width. The tibial plateau lateral margin should normally line up with the lateral margin of the femoral epicondyle. The articular width of the proximal tibia should be slightly larger than the distal femoral articular width, while the total tibial condylar width should be slightly less than the overall femoral condylar width.
Other potential indications for operative treatment of tibial plateau fractures may exist as well. Difficulty/inability to comply with non–weight bearing either due to cognitive deficits or injuries to multiple limbs may be a reason to proceed with surgical management in order to prevent displacement and allow early mobilization. The decision to proceed with surgical management must be individualized to the patient being treated, with consideration of both the risks and the benefits of surgery. Open fractures and compartment syndrome are indications for surgical treatment, although these do not always necessitate internal or external fixation in cases of nondisplaced and stable fractures. Indications for operative treatment of tibial plateau fractures are listed in Box 5.1 .
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Articular step-off of ≥3 mm (1 mm in young and highly active patients)
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Varus/valgus instability of ≥5–10 degrees
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Most bicondylar fractures, medial condyle fractures, and tibial plateau fractures with metaphyseal comminution
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Articular gap of ≥3 mm (plateau widening)
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Need for early weight bearing
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Open fracture
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Compartment syndrome
Percutaneous Fixation
Percutaneous fixation (PF) of tibial plateau fractures is performed in conjunction with fluoroscopy, arthroscopy, or both. PF can be used alone or as an adjunct to open fixation. PF is most applicable to situations where minimal to no displacement is present, where compression through lag screw fixation is sufficient for fracture fixation (most often in noncomminuted fracture segments), and when there is a need to avoid making large incisions to place fixation (e.g., to avoid small skin bridges, traumatic wounds).
Proper visualization of the tibial plateau is paramount to ensure an appropriate reduction and placement of hardware. Anteroposterior (AP) fluoroscopy views can be taken in a straight AP view and in a 10-degree caudad view in order to look down the slope of the plateau. This second view is helpful during placement of hardware to ensure that lag screws are placed in the subchondral bone without penetration through the joint surface. On this view, the articular surface should overlap on itself and make one solid radiographic line. Multiple angle AP views can also be taken to evaluate reduction and look for step-off deformity. Lateral views should aim to overlap the medial and lateral tibial condyles and allow the surgeon to evaluate reduction in the sagittal plane.
Direct visualization of the tibial plateau articular surface can be achieved through the use of arthroscopy ( Fig. 5.1 ). With arthroscopy, care must be taken not to cause extravasation into the tissues of the lower leg, which may already have some degree of damage from the initial trauma insult. Fluid extravasation into a closed compartment can induce a compartment syndrome. The operating surgeon should be aware of this if using arthroscopy to assist visualization. “Dry” scoping (using the arthroscope without water) is a technique that can be used to help avoid fluid extravasation. However, in the setting of a percutaneous approach, this can make visualization difficult (dry scoping during open approaches can be an excellent adjunct for visualization, as discussed later). An arthroscopic pump should be used with great caution or not at all in these cases. Gravity flow fluid with a separate inflow cannula may be desirable to allow for sufficient flushing of the joint. Medial and lateral portals can be established for the arthroscope and instruments (shaver, probe, etc.) and a superolateral portal for inflow. It is necessary to use a suction-shaver to remove clot in the knee and debride clot at the fracture site to provide visualization.
Several reduction instruments and techniques are available in these cases ( Fig. 5.2 ). When slight step-off or gap deformities exist, large pointed clamps (Weber, periarticular, etc.) can be used to obtain reduction. By placing both clamp tines onto bone through small stab incisions and with a force across the knee that opens up the joint space where the reduction is taking place (i.e., varus force when reducing a lateral plateau), the clamp can be twisted to elevate an inferiorly displaced fragment and then squeezed down in order to reduce and compress the fragment. In some instances, a Freer elevator may first need to be inserted into the fracture site and used to disimpact the fracture so it may be mobilized.
A ball spike (or Picador) is an invaluable tool in percutaneous (and open) reduction for tibial plateau fractures. This instrument can be placed through a small incision and used to push the fracture fragment in a desired direction (elevate, compress, etc.). A femoral distractor or external fixator can also be used to help obtain the length of the fracture and to apply varus or valgus forces across the knee joint. This concept is discussed in further detail in the Open Reduction and Internal Fixation (ORIF) section.
Articular surface depression within the central portion of the lateral condyle can be a more difficult problem to address percutaneously. This can be accomplished by making a small incision at the metaphyseal flare. If there is no break in the cortex in this region, a 4.5-mm drill bit can then be used to open the cortex. A long, curved tamp can then be inserted it into the hole created in the metaphysis and directed toward the depressed articular segment. Visualization of tamp placement using fluoroscopy can guide the tamp to the correct position on AP and lateral views. The bone can then be gently tapped back into place with a mallet, and reduction can be checked via fluoroscopy, arthroscopy, or both. An additional reduction technique that can be used here is balloon tibioplasty. This involves inserting an inflatable balloon (often a kyphoplasty balloon) into the tibial metaphysis just beneath the depressed segment and slowly inflating the balloon until the fracture has been reduced ( Fig. 5.3 ). This technique may provide a more widespread and even pressure to the depressed fragment than a bone tamp does with less destruction to the tibia. Once the depressed fragment has been reduced, the metaphyseal bone void can then be percutaneously filled with a bone void filler, such as a calcium phosphate cement.
Another helpful reduction technique is to use medium to large (2.0–3.2 mm) K-wires. These K-wires can be drilled into a large depressed lateral plateau fragment and stopped short of the fracture. The wires are then manipulated to elevate the tibial plateau and, once reduced, can be further inserted across the fracture site into the opposite cortex.
The use of a posterior cruciate ligament (PCL) guide has been reported as a helpful technique in localizing depressed fragments and aiming guidewires to guide tamp and screw placement. The targeting portion of the PCL guide can be placed over the skin. Then, an entry point remote from the articular depression can be used for insertion of instruments in order to get accurate placement of instrumentation and the best angle possible for articular surface reduction ( Fig. 5.4 ). This may be especially useful in percutaneous treatment of posterolateral tibial plateau fractures where instrumentation and fixation can be brought across the plateau accurately from the medial side.
After reduction has been achieved at the fracture site, provisional fixation using K-wires can be utilized to hold the reduction if necessary. Fixation is most often performed parallel to the articular surface, and often compression is desired to provide absolute stability and primary bone healing at the articular fracture site. Compression can be achieved through clamping the fracture and/or through placement of lag screws. Screws of various sizes are used for fixation in these instances (from 3.5, 4.0, 4.5, 6.5, up to 8.0). The size of the screw used may depend on fragment size, patient size, and other fixation being utilized. Lag by design (i.e., partially threaded screws) or lag by technique (i.e., overdrilling the near cortex) may be employed to compress fracture fragments. Screws may be placed with or without washers depending on bone quality and surgeon’s preference. When placing screws for PF, it is helpful to ensure bicortical placement to improve construct strength. In the case of wedge fracture fragments, it is beneficial biomechanically to place a screw at the distal apex of the fracture fragment as a buttress screw to help prevent inferior displacement, in addition to subchondral screws ( Fig. 5.5 ).
Open Reduction and Internal Fixation
Many tibial plateau fractures, especially those resulting from a high-energy mechanism of injury, are treated with ORIF of the displaced joint surface. Large displacement and comminution of the joint surface can make percutaneous reduction and fixation less likely to result in successful radiographic outcomes. Direct visualization through an open approach allows for direct manipulation of displaced fragments. The decision of which approach or approaches to use is important and will depend on the fracture pattern present. Chapter 1 provides descriptions of several approaches to the tibial plateau.
In unicondylar lateral tibial plateau fractures, an anterolateral approach is often utilized for fixation. Once exposure is obtained and meniscus and capsule are retracted superiorly (see Chapter 1 ), a varus force applied across the knee will permit exposure across the lateral tibial plateau to the tibial spine. The transverse submeniscal arthrotomy can extend from the patellar tendon back to the posterolateral plateau. Varus force across the knee can be applied manually or through
A 48-year-old male presented to the emergency department after a fall from a ladder with isolated right knee pain. The patient was hemodynamically stable. His pulses were symmetric with no sign of compartment syndrome. No associated injuries were present ( Fig. 5.6 ).
A knee immobilizer was placed, ice was applied, and elevation was performed overnight. The patient was taken to the operating room the following morning. Intraoperative examination under anesthesia showed greater than 10 degrees of instability with varus stress testing. Open medial buttress plating was performed with percutaneous treatment of the lateral plateau ( Fig. 5.7 ).
As an alternative to a femoral distractor, an external fixator may be used. Half-pins are placed as mentioned earlier, and clamps and carbon fiber rods are then added to the pins, manual distraction applied, and clamps tightened. A third clamp can then be placed on the carbon fiber rod just proximal to the distal pin and tightened to the bar. A large lamina spreader is placed between the two distal clamps, and the most distal clamp is loosened. The lamina spreader is used to move the distal pin and clamp more distal on the carbon fiber rod, providing further distraction. The distal clamp is then retightened, and the lamina spreader can be removed ( Fig. 5.9 ).
Another technique that can be used to gain visualization within the joint is by using an arthroscope without fluid (dry scope). After the submeniscal arthrotomy has been performed, an arthroscope can be placed beneath the meniscus to visualize across the plateau. If necessary, the scope can also be placed through anterolateral or anteromedial portals.
With the arthrotomy performed and direct visualization of the joint, the lateral meniscus can be inspected. Tears in the periphery can often be repaired, whereas more central tears will be debrided. Despite having an open approach with the arthrotomy, an arthroscopic backbiter is a helpful tool to easily reach in and debride the meniscus back to a smooth and stable edge ( Fig. 5.10 ).
In order to gain access to the more depressed medial segments of the lateral plateau, the lateral cortical fragment will often need to be “booked” open. A Cobb elevator or an osteotome can be placed within the sagittal fracture line and is used to lever open the lateral plateau ( Fig. 5.11 ). This can be held open with a lamina spreader or with a self-retaining retractor. Reduction then proceeds from medial to lateral on the tibial plateau ( Box 5.2 ).
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Double osteotomes used to disimpact and lever depressed fragments into place
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Pointed clamps
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K-wire joystick
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Tamp and mallet
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Distractor
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Ball spike
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Push/pull device
Depressed articular fragments are often impacted into the metaphyseal bone and must be first disimpacted with an osteotome or elevator. The osteotome should be placed at least 1 cm below the articular surface to elevate a sufficiently large osteochondral fragment. Once the osteotome is placed, it can be used to elevate the fragment with superiorly directed force on the osteotome directly. As an alternative, a second osteotome can be placed just beneath the first, and the osteotomes can be spread apart to lever the articular fragment back into place ( Fig. 5.12 ). Cobb elevators, Freer elevators, or a tamp with or without the simultaneous use of an osteotome can also be used to elevate fragments ( Fig. 5.13 ).
