Introduction
Historically, restoring the bony architecture in tibial plateau fractures has been the focus of surgical management. While this remains the primary objective in treatment algorithms, management of the soft-tissue structures around the knee has become a secondary objective. Failure to address soft-tissue compromise can lead to continued pain or instability to the knee. This chapter focuses on the nature of the soft-tissue problem, recognizing the entire extent of injury, and surgical techniques to address specific ligament or meniscal pathology.
Not Just a Bone Injury
The bones provide very little stability to the knee joint, in comparison to other highly constrained joints like the hip. Instead, the knee relies on a variety of soft-tissue structures to provide stability of this hinge joint. Ligaments, capsule, and the menisci provide important static stabilizers, and injury can result in instability and poor long-term outcomes. As a result, treatment plans that focus only on the bone, without addressing soft tissues, can fail to restore stability and may lead to a less than functional knee. Despite our best efforts in the treatment of tibial plateau fractures, patients continue to have pain, instability, deformity, wound complications, and stiffness.
In the past, management of the soft tissues primarily focused on the skin and handling of the soft tissues during surgical management. The routine use of temporary external fixation and delaying definitive internal fixation until the inflammatory response of the soft tissues has resolved have led to lower wound complications. , , , While this tactic has certainly helped in managing the soft tissue, it only addresses part of the problem. More recently, an increased focus on the ligaments and menisci has been the topic of more clinical research.
While high-energy mechanisms are more commonly associated with soft-tissue injuries, low-energy injuries can also affect the ligaments and menisci. When angular, rotational, and axial loads are applied to the knee, both static and dynamic stabilizing structures can be injured. A large axial load is not as common in lower-energy mechanisms, but patients can certainly be exposed to rotational or angular loads. ,
Incidence of Soft-Tissue Injury in Tibial Plateau Fractures
Bennett and Browner began to shed light on the associated injuries in tibial plateau fractures in 1994. By using a combination of diagnostic tools, soft-tissue injury was described in 30 patients with tibial plateau fractures. Overall, the incidence of soft-tissue injury was 56%. The most common pathology described was injury to the meniscus and medial collateral ligament (MCL), reported in 20% of patients. In addition, injury to the anterior cruciate ligament (ACL) was noted in 10% and 3% had injury to the lateral collateral ligament (LCL). , Specific soft-tissue injuries were also correlated with certain bony injuries. Injury to the MCL was commonly associated with Schatzker type II injuries, while injury to the meniscus was more common in type IV injuries. , A couple of years later, Colletti et al. highlighted the high incidence of soft-tissue injuries in these fractures. Some form of soft-tissue injury was noted in 28 of 29 patients with acute tibial plateau fractures. The MCL was the most commonly injured ligament (55%), and the lateral meniscus was torn in 45% of patients. Most likely due to the sample size, they were not able to correlate certain soft-tissue injuries with fracture type or degree of articular depression. Interestingly, complete ligament disruptions and meniscal tears have been described even in minimally displaced plateau fractures.
In 2005 and 2010, two large studies highlighted the incidence of soft-tissue injuries in tibial plateau fractures. Using magnetic resonance imaging (MRI), Gardner et al. evaluated 103 patients who underwent operative repair of a tibial plateau fracture. Confirming Colleti’s findings, 99% of patients had some form of soft-tissue pathology, with the most common injury being a tear of the lateral meniscus (91%). In addition to meniscal injury, complete tear or avulsion of at least one ligament was found in 77% of patients. The ACL was the most common ligament injured, followed by the LCL, MCL, and posterior cruciate ligament (PCL). Table 6.1 describes the specific incidences of injury to the ligaments and menisci. In addition to the larger sample size, Gardner et al. also highlighted other soft-tissue structures that may be injured in plateau fractures by specifically addressing the structures of the posterolateral corner (PLC). Of the 103 patients, tears of the popliteofibular ligament and/or the popliteus were found in 68%. Stannard et al. published a similar article in 2010. They also evaluated 103 tibial plateau fractures with MRI. In their case series, 71% of patients had at least one major injured ligament and half of the patients had more than one torn ligament. In addition to describing the high incidence of soft-tissue injury, this report was the first to correlate a higher incidence of soft-tissue injury with severity of the bony injury. The authors concluded that higher energy fracture types (Schatzker types IV–VI) had a higher incidence of soft-tissue pathology compared with lower energy fractures (Schatzker types I–III) ( Table 6.2 ).
| Structure | % (Absolute Number) |
|---|---|
| ACL | 57 (59) |
| PCL | 28 (29) |
| MCL | 32 (33) |
| LCL | 29 (30) |
| Medial meniscus | 44 (45) |
| Lateral meniscus | 91 (94) |
| PLC | 68 (70) |
| Schatzker Type | % With Ligament Injury |
|---|---|
| I | 46 |
| II | 45 |
| IV | 69 |
| V | 85 |
| VI | 79 |
Evaluation of Soft-Tissue Injuries
Identification of associated soft-tissue injuries in the setting of tibial plateau fractures can be challenging. A traditional examination of the knee with a ligamentous injury is usually not possible in the acute setting. Therefore, examination under anesthesia and advanced imaging play an important role in diagnosis.
Obtaining the correct diagnosis begins with understanding the mechanism of injury. As discussed previously, the suspicion for soft-tissue injury should heighten with increasing energy mechanisms. For example, an axial load from a motor vehicle accident may have a variety of ligamentous and meniscal injuries, while a low-energy valgus load to the knee may only have injury to the lateral meniscus and MCL. As with most fractures, diagnostic imaging usually begins with radiographs. Using a combination of anteroposterior (AP), lateral, and oblique views can usually provide a clear understanding of the primary fracture lines. A modified AP view in which the beam shoots down the normal posterior slope of the tibia can also be helpful to assess differences between the slopes of the medial and lateral aspects of the plateau. , , Contralateral radiographs can also be helpful in assessing bony alignment and subtle discrepancies of the medial and lateral joint spaces. As with the bony injury, soft-tissue evaluation starts with initial radiographs. Joint subluxation in either the coronal or sagittal plane can be an indicator of ligamentous injury. Fracture of the fibular head or dislocation of the proximal tibiofibular joint can be a sign of lateral sided compromise.
Preoperative stress imaging has primarily now been replaced by advanced imaging techniques, such as MRI or computed tomography (CT). However, intraoperative stress imaging, particularly after bony stabilization, continues to play an important role. Because of the excellent bony detail provided, CT remains the most commonly used advanced imaging technique, but it lacks soft-tissue detail. , , , In fact, a study that compared CT with MRI in the diagnosis of soft-tissue injury found that CT only had a sensitivity of 80% for ligamentous tears. Therefore, MRI has remained the gold standard for evaluating ligamentous and meniscal injuries, but its role in the setting of tibial plateau fractures remains controversial. , , As MRI techniques have improved, the author has found that MRI provides appropriate evaluation of the soft tissues, while not sacrificing bony detail.
Several studies have attempted to correlate bony findings with concomitant soft-tissue injuries in hopes to negate the need for MRI. Sixty-two patients with Schatzker type II fractures were evaluated by Gardner et al. They found that articular depression of greater than 6 mm and condylar widening of greater than 5 mm were associated with a lateral meniscus tear 83% of the time. In addition to correlation with lateral meniscus tears, a later study showed that condylar widening of greater than 8 mm and articular depression of greater than 6 mm were found to have a high incidence of concomitant cruciate and collateral ligament injuries. A definitive amount of articular depression or condylar widening that correlates with soft-tissue injury has yet to be fully accepted, but it is generally understood that with increasing depression or condylar widening, the incidence of soft-tissue pathology increases. , ,
In addition to obtaining the correct diagnosis, it also appears that MRI alters treatment plans. Holt et al. found that by adding MRI, the treatment plan changed in nearly 20% of patients. In addition, MRI has been shown to have a higher interobserver agreement in fracture classification. Comparing plain radiographs, CT, and MRI, Yacoubian et al. showed that surgeons agreed 85% of the time with MRI and 73% of the time with CT. In addition, treatment plan agreement was greatest with MRI, 86% compared to 77%.
The routine use of MRI for tibial plateau fractures remains controversial, likely due to cost and availability. Unfortunately, there has been little success correlating reliable radiographic parameters to predict soft-tissue injuries. Therefore, many authors who have evaluated the different advanced imaging modalities recommend MRI. , , , Currently, MRI is the advanced imaging technique of choice at the author’s institution. While there may be a small initial learning curve for those that traditionally used CT, anecdotally the transition to MRI from CT seems to be quite easy.
Therapeutic Options/Surgical Techniques
The surgical techniques of external fixation and open reduction internal fixation (ORIF) of tibial plateau fractures are well established and discussed in previous chapters. A foundational principle in the surgical management of these fractures is respect of the soft tissues. This concept was reinforced in a study by Egol et al. in which 57 high-energy plateau fractures underwent initial external fixation followed by staged ORIF. Compared with previously published data, a 5% wound infection rate was reported, in contrast to 13% to 88% in prior studies performing acute ORIF. In general, the following algorithm exists at the author’s institution. Length-stable, low-energy unicondylar plateau fractures usually undergo ORIF within 5 to 7 days as long as the soft-tissue envelope is amenable to an incision. Bicondylar, length-unstable fractures, especially those that are higher energy, undergo initial external fixation followed by eventual ORIF in 7 to 21 days. As mentioned previously, MRI is used in both cases for preoperative planning purposes.
Currently, scant literature exists to guide the management of soft-tissue injuries in combination with plateau fractures. Therefore, most of the treatment algorithm is built on experience and the principle of obtaining a stable knee through full range of motion. It is also believed that the meniscus is an important protector against posttraumatic arthritis, and therefore meniscal pathology should be addressed whenever possible.
In general, ORIF is performed through anterolateral and medial approaches to the proximal tibia and knee, both of which can be used to address the soft tissues. Lateral approaches should be performed in conjunction with a submeniscal arthrotomy. , , , This provides direct visualization of the plateau and also allows the surgeon to evaluate the lateral meniscus. In most cases of lateral meniscus tears in combination with plateau fractures, the meniscus tear is peripheral and amenable to repair. If a tear is present, an outside-in repair is performed using nonabsorbable sutures (author usually uses 2-0 FiberWire). The suture is passed through the capsule, into the meniscus, and then back through the meniscus and capsule in either a horizontal or vertical orientation. The suture is then tied on the outside of the capsule to secure the repair. In most cases, 3 to 4 sutures are used. Medial meniscal tears are usually addressed by arthroscopy, either acutely or later in the recovery. For example, a bucket-handle tear would be addressed at the time of ORIF, but a horizontal tear may be followed clinically and only addressed if symptomatic. Arthroscopic repair in the acute setting can be quite challenging, and positioning the knee in an optimal position may not be possible with an acute fracture. Therefore, only significantly displaced medial meniscal tears are addressed acutely.
Based on the preoperative MRI, if there is suspicion of a PLC injury, the incision should be adjusted slightly to allow access to the fibular head and provide access for dissection of the peroneal nerve. For the medial side of the knee, the standard medial approach allows easy access for repair or reconstruction of the collateral.
The choice between repair and reconstruction of the collateral ligaments can usually be made preoperatively by findings on the MRI. For example, mid-substance tears are usually reconstructed, while footprint avulsions are repaired. In addition, stress views after ORIF are used to assure appropriate stability. If coronal plane instability is present, collateral ligament repair or reconstruction is important to obtain appropriate stability to the knee. If the instability is recognized at a later stage, reconstruction is usually warranted instead of repair.
Cruciate injuries can be quite challenging due to the fact that reconstructions require sockets that are passed through areas of fixation for the plateau fracture. For large tibial avulsions, the fractures are usually addressed at the time of ORIF with either screw fixation or suture repair. PCL avulsions can usually be visualized through the posteromedial approach and can be secured with fixation of posteromedial fracture fragments. Mid-substance tears are usually treated using a staged approach. For example, the tibial plateau undergoes ORIF and the cruciates are not addressed. Once adequate bone healing has occurred, instability is assessed with physical examination of the ACL and/or PCL. If instability is noted, partial removal of implants is performed to allow for reconstruction. Surprisingly, this is seldomly needed. Anecdotally, these patients do not seem to complain of instability symptoms later. It may be that the fracture healing response allows for healing of the cruciates, similar to the increased healing rates of meniscal injuries in the setting of ACL reconstruction.
Surgical Management of Collateral Injuries
As described earlier, most cruciate injuries are managed nonoperatively initially, and detailed techniques for cruciate reconstruction are outside the scope of this chapter. However, collateral injuries are often addressed at the time of ORIF, so it is prudent for the treating surgeon to be able to perform repair or reconstruction if indicated.
A thorough understanding of anatomy is paramount to the success of either a repair or a reconstruction. The MCL originates at the isometric point of the femur. The most reliable method to find this isometric point is using a lateral radiograph. The isometric point is found at the intersection of a line drawn down the posterior femoral cortex and Blumensaat’s line ( Fig. 6.1 ), approximately 3 mm proximal and 5 mm posterior to the medial epicondyle. If repairing an MCL avulsion off the femur, the ligament should be repaired down to that point. If performing a reconstruction, a tibialis anterior allograft is used and should be at least 150 mm in length. The femoral limb of the reconstruction begins at the isometric point. Several options exist for fixation of the graft at both the origin and insertion points. The insertion of the MCL is on the posteromedial aspect of the tibia, just distal to the semitendinosus. It is on average approximately 6 cm from the joint line. The new ligament should pass underneath the pes anserinus tendons prior to docking at the tibial insertion site. The graft is usually tensioned with the knee at 30 degrees of flexion with slight varus stress. In more severe injuries, the entire posteromedial corner (PMC) may need to be reconstructed. The primary ligaments reconstructed in this setting are the MCL and the posterior oblique ligament (POL). An option for reconstruction is to use a double-ended graft that is docked at the isometric point on the femur. The MCL is then reconstructed in a similar manner as described earlier, and the graft for the POL is passed behind the semimembranosus tendon and then anchored into the posteromedial tibia ( Fig. 6.2 ). With the graft in place, a posteromedial capsular shift/imbrication can be performed, as a capsular stretch injury and redundant capsule will often be present.
