12.56 Tibial plateau fractures

Fractures of the proximal tibia present a challenging problem as the injury involves a principal weight-bearing joint and severe injuries can lead to functional impairment. A flexible approach is required to adapt treatment to the patient, fracture pattern, and clinical and radiological findings. The treatment options range from non-operative management through limited internal fixation to open reduction and internal fixation (ORIF) or external fixation. Regardless of the treatment method employed, the aim is to provide a stable, pain-free, and well-aligned joint whilst avoiding complications.

The aim of this chapter is to provide an overview of the injury, classification, management and technical tips in managing this type of fracture.

In a consecutive series of 285 tibial plateau fractures treated at our institution, there were 168 female and 117 male patients giving a female: male ratio of 1.4:1. Most of these fractures were isolated injuries with multiple trauma accounting for only 1.4% of cases. There were 149 (49%) undisplaced fractures and 146 (51%) displaced fractures. Although the mean age of patients with plateau fractures was 58 years, there appeared to be a bimodal incidence with a peak of younger patients and a larger peak in the seventh and eighth decades of life (Figure 12.56.1). Simple falls and pedestrian accidents accounted for 70% of cases. Dogs running into their owners were a surprisingly common cause and accounted for 15% of fractures (Figure 12.56.2).

The tibial plateau is formed by the medial and lateral condyles separated by the tibial (intercondylar) eminence. The intercondylar eminence is the site of attachment of the meniscal horns and the anterior cruciate ligament. There are important soft tissue structures that attach to the tibial plateau including the knee joint capsule, and the medial and lateral meniscotibial ligaments. The medial collateral ligament comprises a deep and superficial layer. The lateral collateral ligament is attached from the lateral epicondyle to the fibular head. The anterior cruciate ligament is attached to the intercondylar eminence between the tibial spines and the posterior cruciate ligament arises from the posterior aspect of the plateau in the midline. Further meniscal attachment is provided by the meniscotibial ligaments at the periphery of both sides. The attachment of the joint capsule can extend 1.5cm below the level of the joint margin, which has particular significance when using fine-wire external fixators, which are often situated, close to the joint. If they penetrate the capsule, pin track infection may result in septic arthritis.

Three additional structures have potential significance in assessment and management of tibial plateau fractures. The fascia lata attaches at Gerdy’s tubercle, and is sometimes disrupted by the injury or requires to be released during the exposure and fixation of the fracture. The tendons of gracilis, sartorius, and semitendinosis are attached anteromedially at the pes anserinus and need to be reflected during exposure of the medial plateau.

The surface of the tibial plateau forms a 10-degree posterior slope in relation to the long axis of the tibia. The shape of the medial condyle is concave and has an average 3-mm thick hyaline cartilage articular surface that the medial meniscus covers about 50% from the periphery. It has less of a flare and as a result is less prone to the shear forces that render the lateral plateau more susceptible to fracture. The lateral plateau is convex with an average 4-mm thick hyaline cartilage that is almost completely covered by the lateral meniscus. Load bearing on the lateral plateau is transmitted mainly through the lateral meniscus, unlike the medial plateau where the load is distributed equally through the meniscus and the exposed articular surface.

The medial plateau surface is lower in the transverse plane than the lateral plateau and this can be easily seen on plain anteroposterior (AP) radiographs. This is significant when elevating a depressed segment of the plateau in assessing the accuracy of reduction and surgeons should be aware that the subchondral line on the lateral side should be higher than on the medial side. It is also important to appreciate that a screw or wire placed subchondrally on the lateral side proceeding medially, perpendicular to the tibial shaft, may penetrate the articular surface of the medial side if the location is very proximal. Ideal screw placement is in the subchondral bone just beneath the articular surface in a ‘raft’ construct.

Several classification systems of plateau fractures have been described. No one system provides a comprehensive description of all fracture patterns encountered. The Hohl and Moore, and Rasmussen systems are mainly of historical interest and no longer in widespread use. The Schatzker classification subdivides the plateau fractures into six groups and has been the most popular method of classifying tibial plateau fractures from plain radiographs and remains in common use today. However, it has some significant disadvantages. Medial plateau fractures are all classified as type IV injuries but there are a wide variety of these fractures. The oblique fractures which are a highly unstable pattern are not specifically covered by the classification (Figure 12.56.3). The type V fracture as originally described was a bicondylar fracture (Figure 12.56.4) with the interspinous eminence still in contact with the tibial diaphysis. However, this is actually a very rare pattern and in most bicondylar fractures the interspinous region is involved in the fracture and is not in continuity with the tibial shaft.

The more comprehensive classification is the AO/Orthopaedic Trauma Association (OTA) system which covers most fracture types and is now being used more commonly. It allows a more detailed description of fracture morphology including separate categories for oblique fractures and a number of categories for bicondylar fracture patterns. However, even this system does not describe the important posteromedial and anteromedial fractures as separate entities. It is worth noting that both classification systems are prone to inter- and intra-observer error.

The AO/OTA classification is based on an alphanumeric system that assigns each major bone and the region of bone involved a number and then subdivides the injuries in that region based on severity. In the case of the tibial plateau, the bone is assigned the number 4 and proximal region is 1. Proximal tibial metaphyseal fractures, which are extra-articular, are classified as type A injuries. Type B fractures are partial articular fractures and type C fractures are complete articular fractures. All fractures involved the plateau are classified as 41 type B and C injuries. Type B1 fractures are simple splits, type B2 are pure depression, and type B3 are split depression fractures. Subdivisions of each category allow for description of whether the injury involves the medial or lateral plateau and the extent of involvement. The type C fractures are bicondylar fractures. Type C1 designates a fracture with a simple articular and metaphyseal configuration. Type C2 is a metaphyseal complex pattern with simple articular pattern and type C3 fractures are complex articular bicondylar plateau fractures.

These fractures are simple splits with no comminution or joint depression. They most commonly involve the lateral tibial plateau and usually occur in young patients with good bone stock. The most common mechanism of injury is axial loading coupled with a valgus force. The strong cancellous bone resists any surrounding articular depression that occurs in older or osteoporotic patients. Wide displacement of the split fracture may be associated with peripheral meniscal detachment and occasionally entrapment of the meniscus in the fracture may occur.

These fractures are intra-articular fractures of the tibial plateau but in addition have an adjacent area of articular depression. These are usually found in older patients or younger patients with higher-energy injuries. They occur when the surrounding cancellous bone is unable to withstand the axial load created by the lateral femoral condyle. The same associated soft tissue injuries occur as with the split fractures.

This is a pure depression fracture of the lateral tibial plateau and principally occurs in older patients, again due to the weaker cancellous bone. Isolated depression fractures are actually quite uncommon—the majority have a split component which is undisplaced and is recognized only on computed tomography (CT) scan or at the time of surgery.

Split or split depression fractures of the medial tibial plateau occur as a result of compression of the medial plateau by a varus force. Many of these are high-energy injuries and are associated with other soft tissue problems. Oblique medial plateau fractures that extend to the interspinous region or into the lateral plateau are fracture dislocations of the knee and are highly unstable injuries. Since all of these fractures involve application of varus force to the knee, there is a possibility of common peroneal nerve palsy.

These fractures involve a bicondylar split with separation of the medial and lateral condyles and a variable involvement of the diaphysis. The proposed mechanism for this fracture is pure axial load on the extended knee. Bicondylar fractures account for 10–15% of all plateau fractures. The involvement of the intercondylar area in the fracture may compromise cruciate ligament attachments. The higher energy required to produce this fracture patterns means they are associated with greater soft tissue injury and an increased risk of compartment syndrome.

The majority of tibial plateau fractures are isolated injuries but initial management involves careful general evaluation in line with ATLS® principles to exclude other injuries. The most common mechanism of fracture is usually a combination of an axial load coupled with a valgus force. In this situation the medial collateral ligament acts as a hinge on the medial femoral condyle that then drives the lateral femoral condyle into the lateral tibial plateau. In patients with normal bone stock, this leads to a sagittal split of the lateral plateau. Damage to the articular surface of the lateral plateau with additional comminution is frequent, leading to a split depression fracture. Elderly patients with poorer bone stock often appear to have depression of the articular surface without a split fracture. However, pure depression fractures are uncommon and even patients who appear to have isolated depression usually have an undisplaced split component present.

Varus stress in combination with compression is a much less frequent mechanism of injury but can result in a fracture of the medial plateau. Progression of varus deformity may result in disruption of the posterolateral corner structures and subsequent traction injury or even avulsion of the common peroneal nerve. Occasionally a combination of hyperextension and varus deformity can occur and this leads typically to an anteromedial plateau fracture which may be associated with a posterior cruciate ligament and posterolateral corner ligament injury (Figure 12.56.10)

High-energy injuries with axial loads in addition to valgus or varus forces usually result in bicondylar plateau fractures. These fractures are often associated with a significant degree of soft tissue injury. As a consequence of the posterior slope of the tibia, the distal femoral condyles are subsequently directed posteriorly, leading to disruption of the joint capsule, cruciate and collateral ligaments and potential injury the neurovascular bundle.

Careful observation of the soft tissues is required in all cases, particularly to detect blisters, devitalized skin, and open fractures all of which will influence the clinical decisions regarding management.

An assessment of the neurovascular status of the limb should be performed and documented. If there is any doubt regarding the vascularity of the limb in high-energy fracture patterns angiography is required. Injury may take the form of a thrombus, occult intimal tear or, rarely, complete disruption of the artery. Either angiography or a CT angiogram should reveal these injuries. Fractures of the medial plateau may result in traction injury or avulsion of the common peroneal nerve and is present in 10% of these fractures. The neurological status of the limb should be examined and documented on admission.

Compartment syndrome is not commonly associated with the simpler fracture patterns (split, depression and split depression patterns). However it does occur in 5–10% of patients with bicondylar fractures and the high-energy oblique fractures and a high index of suspicion is warranted in these cases. Compartment pressure monitoring is advisable in these patients.

Plain AP and lateral radiographs of the tibial plateau are required in all cases. A ‘Moore’ view can be added, which is an AP view taken with 10–15-degree caudal tilt (Figure 12.56.11). This accounts for the posterior slope of the tibial plateau allowing a better evaluation of the joint surface. Oblique views taken at 45 degrees and plain tomography were commonly used in the past but have been superseded by CT scanning.

Modern CT scanning with sagittal, coronal, and three-dimensional reconstructions are not necessary for simpler fracture patterns but should be considered in more complex injuries, particularly bicondylar fractures. However, in some simple fracture patterns there may be some doubt about the diagnosis, the extent of plateau involvement or the degree of joint depression and CT scans are useful in these cases to determine the need for surgery. The coronal views show the size and location of all articular fragments. The use of CT reconstructions, as well as intraoperative CT has been shown to be superior to fluoroscopy in assessing fracture reduction. Magnetic resonance imaging (MRI) has been used, where available, to delineate occult fractures, soft tissue disruption and impaction of the articular surface. It is most useful in fracture patterns specifically associated with ligamentous injury, particularly anteromedial plateau fractures. In these cases the ligament injury is often impossible to diagnose clinically due to the presence of the unstable fracture.

If the fracture pattern involves the anteromedial portion of the tibial plateau then a careful examination of the posterolateral corner should be undertaken. Regardless of the mode of imaging employed, the objective is to provide a full assessment of the fracture pattern and any associated soft tissue disruption, which facilitates preoperative planning.

The management of tibial plateau fractures is determined by the clinical evaluation of the patient and the limb, and the morphology of the fracture. Factors that will have a major influence on treatment choice are the presence of an open wound, a fracture dislocation, concurrent and pre-existing health or knee problems, age and activity level, bone quality, anticipated patient compliance with rehabilitation, and treatment expectations. The successful treatment of these injuries is a dependent on careful treatment selection and a properly structured rehabilitation programme. Even when this occurs many patients take over a year to recover knee muscle function and motion. Patients over 40 years of age recover significantly slower, and some have residual impairment of movement and muscle function.

Any open fractures should be initially covered with a sterile dressing and administration of broad-spectrum intravenous antibiotics. The patient’s tetanus status should be addressed. Initial debridement and irrigation with 10L of normal saline within 6h of injury is required.

If there is an associated vascular injury-requiring repair, then ideally the fracture should be stabilized first without delay. Complex fracture patterns may require temporary bridging external fixation across the knee joint. Pins should be placed as far as practical away from any future surgical incisions. Following a vascular repair, fasciotomies are commonly required, and definitive fracture fixation may be delayed 48–72h until the fasciotomies are closed.

Closed unstable fractures without vascular injury, can be fully evaluated clinically with appropriate imaging and preoperative planning prior to definitive surgery. During this time, the limb may be immobilized in a padded long leg splint. Deep vein thrombosis (DVT) prophylaxis should be prescribed and intermittent foot compression devices may be used on the contralateral foot as well.

In the past this was a commonly employed treatment modality but with modern imaging techniques and a wider variety of surgical options, a smaller proportion of tibial plateau fractures are suitable for non-operative treatment in modern practice. Pure split, split depression, and depression fractures that are stable through 90 degrees of flexion with less than 3mm of articular depression are suitable. The bone quality, concomitant medical problems, and functional demands in elderly patients may also influence the decision to opt for non-operative treatment. If there is any doubt regarding the suitability of the fracture for non-operative treatment, a CT scan is the most helpful additional investigation to determine the extent of joint surface involvement and the degree of depression. Central depression fractures of the lateral plateau with minimal depression of the articular surface are suitable for non-operative treatment due to the load bearing nature of the lateral meniscus that protects the damaged articular surface.

If non-operative treatment is selected there are several forms of immobilization available. A full-length cast can be used but a cast braces with a hinge at the level of the knee to allow some knee motion is preferable. Removable hinged braces that do not enclose the foot are a good choice for stable fractures in compliant patients. Accurate placement of the brace by an orthotist or surgeon is essential and the patient, or carer, must be able to reproduce correct placement of the device for this to be successful.

Patients treated non-operatively should be allowed touch weight bearing for the first 6 weeks and progression to full weight bearing over the subsequent 6 weeks is allowed provided there is radiographic evidence of fracture healing. Radiographs are required in the first 2 weeks of treatment to check for loss of fracture position. If there is any loss of position, this may necessitate conversion to operative treatment.

Operative treatment is indicated in unstable fracture patterns with joint surface displacement in excess of 3mm. Operative treatment is indicated in all open fractures, and those associated with significant soft tissue problems (compartment syndrome, ligament injury, common peroneal nerve palsy, and vascular injury).

A single linear anterior paramedian incision is suitable for access. It has the advantage of being used for a subsequent knee arthroplasty should one be required. A subperiosteal exposure of the lateral plateau is readily carried out. This approach allows excellent exposure of the lateral plateau fracture and facilitates reduction of the proximal tibial condyle prior to secure internal fixation. Direct visualization of the joint reduction is best achieved with an anterolateral arthrotomy. A plane is then developed between the capsule and edge of the lateral meniscus. The meniscus is then elevated to expose the plateau by incising the lateral meniscotibial ligaments. Some authors have proposed incising the lateral horn of the meniscus but we prefer to avoid this. A curved anterolateral incision can also be used. The main drawback of this exposure is that the curved portion is not suitable for use if knee arthroplasty is needed and may increase the risk of wound complications at subsequent surgery.

The choice of fixation depends on the fracture pattern and the degree of comminution. Pure split fractures can be fixed with cannulated lag screws, buttress plating, and locking plates. Biomechanical studies have demonstrated that lag screw fixation is usually sufficient in good quality bone for fixation and plating is not generally required. If there is a single large fragment or significant comminution, particularly at the metaphyseal base, then a laterally based buttress plate or antiglide plate should be used. With split depression fractures, the depressed area needs to be elevated and fixed with a buttress plate or periarticular raft. There is usually a subchondral defect once the joint surface is restored to the anatomical position. The addition of bone graft or bone substitutes is often required in addition to fixation to support the joint surface. Bone graft substitutes are a good choice in older patients where autogenous bone graft may be of poor quality.

Medial fractures are usually the result of high-energy injuries and frequently have associated soft tissue injuries. Almost all fractures of the medial plateau are unstable and require operative treatment, provided the patient is medically fit. Fractures which contain a predominantly split component, can usually be reduced indirectly with gentle traction or a femoral distractor. If the split is coronal then a posteromedial approach may be required. A vertical incision is employed starting posteroinferior to the adductor tubercle extending distal to the joint line by 6cm. The skin flaps are raised to expose the fascia. There is no true internervous plane and the saphenous nerve crosses the approach transversely and should be protected as it emerges between gracilis and sartorius muscles. Incise the fascia over the anterior border of the sartorius and retract this muscle posteriorly along with gracilis and semitendinosus. Separate the medial head of gastrocnemius from semimembranosus to expose the posteromedial corner of the tibial plateau. Further blunt dissection beneath the medial head of gastrocnemius is safe and allows access to the posterior tibia as far as the midline. Those with significant depression of the articular surface require open reduction. Fractures of the medial plateau usually have significant shear forces acting on them and as a result lag screws alone are not to provide enough stability. They require a medial buttress plate to counteract the shear forces acting.

Previously these fractures were treated with dual medial and lateral plates or by a combination of limited internal fixation and external fixation. Since the advent of locking plates, it is possible to fix the two condyles with 6.5-mm lag screws and stabilize the articular segment to the diaphysis with a lateral or medially placed locking plate. Having screws locked into the plate creates a fixed angle device with enough stability to counteract the forces acting on the contralateral tibial plateau. This obviates the need for a second plate with the additional soft tissue dissection this entails.

Fracture patterns that have dissociation of the metaphysis from the diaphysis, represent the most severe injuries. There is no consensus as to the definitive choice of fixation. In principle, however, they all require articular reconstruction and reconnection of the articular segment back to the tibial shaft. Most surgeons now use either locking plates or fine wire external fixation for these fracture patterns.

The method of fixation is influenced to a large extent by the status of the soft tissues. If the soft tissues are in good condition then a long locking plate after joint surface reconstruction is now probably the most popular method of treatment. If the soft tissues are extensively contused or there are fracture blisters then a more cautious approach is necessary. One option is the use of a temporary external fixator spanning the fracture until the soft tissue envelope has recovered and internal fixation can be safely undertaken. The alternative is to use fine wire external fixation as the definitive method of treatment. This may be the only choice if the soft tissue injury is extensive or the bone is of poor quality.

It is difficult to compare the results of different treatments reported in the published literature. There are various reasons for this, including different classification systems and outcome scoring scales being routinely employed. In general, non-displaced fractures and lower-energy fractures such as split, split-depression, and central depression types have a better prognosis. A 20-year follow-up was performed on ten patients who underwent operative fixation. These patients were originally selected for surgery as they had greater than 10 degrees of coronal plane instability in full extension at examination under anaesthesia. Good to excellent results were found in 90% of patients. For the use of limited internal fixation combined with appropriate external support, reports show 90% good or excellent results. The higher energy, more complex fracture patterns present a greater challenge to manage. The Canadian Orthopaedic Trauma Society completed a multicentre, prospective, randomized clinical trial to compare ORIF with percutaneous, limited fixation and application of a circular fixator. The fracture patterns within this series were OTA types C1–3. The follow-up of this group is short term, but at 2 years showed no significant differences with respect to quality of reduction or functional outcome. However, there were a greater number of complications in the internal fixation group and a deep infection rate of 18%. Type C3 fractures treated with medial and lateral plates showed significant residual dysfunction in patients with greater than 2mm articular surface step. This is despite associations with patient age and presence of polytrauma.

Recently there has been increased use of locking plates to treat the more complex fractures, in particular osteoporotic fractures and those with extensive comminution. These devices minimize soft tissue injury by using minimally invasive approaches in conjunction with femoral distractors, K-wires, and percutaneously applied reduction forceps to control the major fragments. Results with this technique have shown a union rate of 96% and deep infection rate of 3.7%. However, malalignment has been reported in a significant number of cases. In comparison, dual plate techniques have been shown clinically to have less malalignment and less subsidence in cadaveric experiments. Although locking plates may provide a more biological solution to bicondylar plateau fractures it is clearly important to tailor the appropriate treatment to suit the patient’s individual bony and soft tissue injuries.

Complications can occur with any of the described fracture patterns, but are more frequent with the higher energy injuries. Prevention, where possible, is the best treatment but in principle good surgical technique, limited incisions and careful tissue handling will reduce their incidence. The outcome of tibial plateau fractures following a complication is difficult to assess due to the heterogeneous nature of the groups reported in the published literature.

This is not frequent in most plateau fractures but must be considered particularly in higher-energy patterns of bicondylar and medial plateau fractures. The most reliable method of diagnosis is by compartment pressure monitoring. Early fasciotomy to decompress the four compartments of the leg is required. This may influence selection of fixation method. However, it does not preclude using internal fixation with a plate, although difficulty may be encountered when attempting wound closure and use of a gastrocnemius flap is occasionally necessary to cover a plate on the medial or lateral plateau.

Incidence of this complication following tibial plateau fractures is reported to be 5–10% and subsequent pulmonary embolus (PE) at 1–2%. Use of anticoagulant prophylaxis, compression pneumatic stockings, and early movement should be used to reduce this complication.

The incidence of this complication correlates well with the degree of soft tissues compromise and the amount of internal fixation required. Intravenous antibiotics should be used for closed fractures treated by internal fixation. Open fractures require adequate debridement, irrigation, antibiotics, and where appropriate soft tissue coverage within 7 days. Previous treatment strategies using large open approaches to implant metalware produced infection rates up to 80%. Modern techniques place greater emphasis on managing and handling the soft tissue envelope, combined with smaller incisions. This has led to a reduction of infection rates, in high-energy fractures, to approximately 10–18%.

The metaphyseal bone of the proximal tibia usually heals without difficulty, resulting in a very low rate of non-union for tibial plateau fractures. When it occurs it is usually with the high-energy fractures and infection must be excluded as a cause. Most of these fractures heal within 6 months. Failure of progression to union at this stage may require revision of fixation with bone grafting of the metaphyseal non-union.

Metaphyseal malunion generally occurs as a consequence of malreduction at the time of initial fixation. Loss of fixation leading to articular incongruity occurs if the articular surface is not adequately supported after reduction but may also occur in very osteoporotic bone. The fracture must be stable from 0–90 degrees with either operative or non-operative treatment. Accurate angular alignment is difficult to maintain in bicondylar fracture patterns and fractures with metaphyseal–diaphyseal dissociation. Patients with articular incongruity may develop painful post-traumatic OA at an early stage, often within 2 years of injury. In these circumstances conversion to total knee arthroplasty may be required. Revision implants are usually necessary due to loss of bone on the tibial side.

The majority of knees regain a function range of movement following treatment of these fractures. Range of movement exercises should be commenced as soon as possible, irrespective of the treatment option selected, to try and prevent this problem. Low energy tibial plateau fractures treated surgically have a favourable outcome at 3–5 years. Recovery tends to be slower in patients over 40 years of age and patients can take over a year to rehabilitate. In general there is significant impairment of movement and muscle function after fracture of the tibial plateau and the majority of patients have not fully recovered 1 year after their injury.

As a consequence of these fractures there is increased chance of damage to the articular surface that can lead to post-traumatic OA. This chance is increased with bicondylar fractures and those with increased comminution. Approximately one-third of patients will develop radiological changes following this fracture and the degree of arthritis is greater with malalignment of more than 5 degrees.

Care should be taken to limit the amount of hardware implanted where possible. Prominent screws should be avoided as painful bursae may form over them. In carefully selected patients removal of the prominent metalware can reduce symptoms. Before removing the metalware, other sources of pain such as occult infection, non-union, malunion, neuroma, and arthritis must be ruled out.

Tibial plateau fractures are complex problems associated with significant complication related to both the injury and treatment. In order to obtain good results, the associated injury to the soft tissue envelope must be taken into account.