12.58 Tibial plafond fractures

Fractures of the tibial plafond or pilon fractures involve the distal tibial articular surface. They are caused at least in part by axial loading. Tibial plafond fractures account for 1–10% of all lower extremity fractures and are more commonly seen in males than females. They occur over a broad age range, but are uncommon in children and the elderly. The average age is 35–40 years.

The distal tibial articular surface is rectangular in shape and forms the ceiling or plafond of the ankle joint. The cancellous bone of the distal tibial metaphysis is organized in dense trabeculae that are oriented at right angles to the articular surface (Figure 12.58.1).

The distal tibia soft tissue sleeve is tenuous. The anteromedial aspect is covered by only periosteum, a thin layer of subcutaneous tissue, and skin. The anterolateral aspect is covered by the tendons of the anterior compartment musculature and the anterior neurovascular bundle (Figure 12.58.2). The anterior tibial artery supplies the anterior aspect of the lower leg, but because of the lack of underlying muscle there are few perforating arteries to supply the skin. The artery’s subcutaneous position makes it prone to injury, which can further compromise perfusion of the skin. ‘Watershed’ areas between the anterior tibial, posterior tibial and peroneal arteries add to the delicate nature of this soft tissue envelope.

The ligaments of the ankle joint affect the way the distal tibia breaks in plafond fractures. The anterior and posterior tibiofibular ligaments are stout ligaments and typically retain their attachments to both the distal fibula and tibial articular surface despite fractures to either one or both of these bones. The fracture lines through the distal tibial articular surface may result in a large anterolateral fragment, also known as the Chaput fragment, and/or a posterolateral fragment either of which can be attached to the distal fibula via intact ligaments (Figure 12.58.3). Therefore, if the fibula is intact, the fragments connected by the tibiofibular ligaments provide a cornerstone to which the rest of the tibial articular surface can be reconstructed. Conversely, if the fibula is fractured, fibular reduction will yield a provi-sional reduction of the lateral side of the distal tibia via ligamentotaxis. Unfortunately these fragments may be relatively small and of little use.

Associated injuries are common because of the high-energy nature of these fractures. Concomitant fractures occur in 15–52% of cases. A high percentage of these fractures are caused by compression or axial load including contralateral calcaneus or tibial plafond fractures, tibial plateau, lumbar vertebrae, and acetabular and pelvic fractures. Chondral abrasions are very common. Injuries to other systems are not uncommon, occurring in up to 25% of cases, and include head, chest, and abdominal injuries.

Approximately 20% of fractures of the tibial plafond are associated with an open soft tissue injury. Closed tibial plafond fractures also have a significant soft tissue injury; fracture blisters are commonly seen (29% incidence in one series). Neurovascular compromise and compartment syndrome although rare, can occur.

Tibial plafond fractures have a different mechanism of injury than malleolar fractures. At least some component of axial loading fractures the distal tibial articular surface, producing comminution or impaction. The vast majority of tibial plafond fractures occur in motor vehicle accidents, falls from a height, direct trauma, and water or snow skiing accidents. The advent of airbags in motor vehicles protects occupants from deadly chest and abdominal trauma so that they survive accidents which produce high-energy lower-extremity trauma, leading to an increase in the incidence of tibial plafond fractures.

Axial compression fractures shatter all or part of the articular surface depending on the position of the foot at the time of impact. A dorsiflexed foot may result in fracture of only the anterior portion of the plafond, whereas in plantar flexion the posterior portion will fracture. The entire plafond may be injured if the foot is in neutral position (Figure 12.58.4).

Low-energy fractures which are primarily rotational may extend into the tibial articular surface. These fractures are radiographically more similar to malleolar fractures and are differentiated by the presence of articular comminution or impaction of the plafond produced by a component of axial compression. More severe axial compressive fractures may be associated with a degree of rotation causing a dislocation of the talus medially, laterally, or posteriorly that typically occurs with rotational injuries. High-energy fractures which occur after a rapid loading rate result in marked comminution of bone and open wounds or closed fractures with severe soft tissue injury. The distal tibia literally explodes (Figure 12.58.5).

The AO/Orthopaedic Trauma Association (OTA) classification 2007 is the most complete and extensive classification of different subtypes of fractures of the plafond. This classification divides fractures of the distal tibia into groups A, B, and C, and then further subdivides them based on the amount of comminution (Figure 12.58.6). Group A consists of extra-articular fractures, group B of fractures involving part of the articular surface, and group C of fractures involving the entire articular surface. It is primarily the B3, C2, and C3 fracture types that are high-energy axial loading fractures and satisfy all definitions of a plafond fracture. B1, B2, and C1 fractures associated with marginal impaction can be considered to be plafond fractures. When combined with an assessment of the soft tissue injury, this classification may prove to be an aid to prognosis and allow comparison between patient groups.

Unfortunately, both this classification system and the Rüedi–Allgower system have been shown to have poor interobserver reliability and intraobserver reproducibility.

Treating these injuries requires accurate assessment of the soft tissue injury which is even more difficult to categorize accurately and reproducibly. Open fractures are classified based on the size of the wound using the criteria of Gustilo and Anderson, which do not address other components of the soft tissue injury or the majority of the fractures which are closed. The Tscherne–Goetzen classification assesses the grade and severity of the soft tissue injury in closed fractures. Although it is frequently cited in the literature, due to difficulties of clinical application, it has rarely been implemented in studies of plafond fractures. In addition, the full extent of swelling and local contusion can only be appreciated after several hours to days.

The mechanism of injury provides insight into the amount of energy imparted to the bone and soft tissue at the time of fracture, which is crucial for surgical planning and for advising the patient on prognosis. In open fractures, assessing the environment in which the injury occurred will guide antibiotic treatment.

The neurological and vascular status of the foot must be evaluated. Absent pulses should be managed by realignment of the extremity and reassessment. Provisional splinting with the extremity aligned prevents further soft tissue trauma. Open wounds are inspected to determine their extent and evaluated for gross contamination. The condition of the skin, amount of swelling, and the presence of fracture blisters must be noted at initial evaluation as well as prior to surgical intervention.

Fracture blisters are common and can be divided into two types: clear-fluid filled and blood-filled. Histologically, both types are disruptions at the dermoepidermal junction, but the blood-filled blisters signify greater injury and have been associated with wound-healing complications when incisions are made through them (Figure 12.58.7).

Standard imaging includes anteroposterior, lateral, and mortise views of the ankle. Repeat radiographs with the limb provisionally reduced provide useful information and should routinely be obtained if the initial radiographs show the talus to be widely displaced. Proximal extension of the fracture or suspicion of more proximal injury mandates that full-length tibia and fibula radiographs be obtained. Some surgeons find views of the contralateral ankle helpful as a template for preoperative planning. Axial computed tomography (CT) scanning helps to define the severity of the injury and aids with surgical planning. The axial plane of the CT scan delineates the size and orientation of the articular fragments. This knowledge is crucial, especially for the less invasive approaches to articular reduction, where limited incisions are placed directly over fracture lines and implants are often applied percutaneously to limit the amount of soft tissue stripping. Coronal and sagittal reconstructions further delineate the fracture anatomy and assist in preoperative planning (Figure 12.58.8).

Tibial plafond fractures are initially managed by provisional reduction, splinting, and elevation to minimize further soft tissue injury. A spanning external fixator with or without fibular fixation is used to maintain length and provisional reduction, and has been used as a means of portable traction prior to definitive treatment. This has the advantage of permitting mobilization. In patients with multiple injuries, open wounds, or compartment syndrome, application of a provisional spanning external fixator should always be part of the initial management.

Casting or splinting has generally been reserved for non-displaced fractures or as a treatment of default, when associated injuries or the severity of the fracture and soft tissue injury precluded any type of operative intervention.

Current fixation of tibial plafond fractures by open reduction and internal fixation can be traced to the AO–ASIF group and their philosophy of obtaining anatomical reduction through wide operative approaches followed by rigid internal fixation to allow for early mobilization. Rüedi and Allgower reported good results with this technique and their method was widely adopted as the ideal form of treatment for this fracture type. A four-step protocol for open reduction and internal fixation was described (Figure 12.58.9):

Since the publication of Rüedi and Allgower’s work, the technique for open reduction has been modified, but the four basic steps or tenets have remained unchanged. The modifications have centred around atraumatic soft tissue technique to avoid skin slough and wound breakdown. Delaying surgery for 7–21 days avoids the time period where interstitial oedema, tense swelling, and tissue ischaemia are most likely to lead to difficult wound closures and subsequent breakdown and infection. This may be the single most important principal that has decreased what was an unacceptably high complication rate. Fracture blisters are unroofed and sterile dressings used, and definitive surgery is delayed until it is clear that swelling is receding. Length and alignment are maintained with temporary joint spanning external fixation. This allows patient mobilization and facilitates subsequent joint reconstruction. The classic surgical approach is through two incisions, one lateral incision paralleling the posterior aspect of the fibula, and an anterior incision over the tibia that curves medially in its distal aspect. Flaps in the subcutaneous layer should not be elevated. If the paratenon of the anterior tibial tendon can be preserved a skin graft can be used, preventing a tight closure. Incisions directly over the anteromedial tibia are through poorly vascularized and damaged skin and may be directly over a location chosen for implant placement. A minimum of 7–12cm between the medial and lateral incisions has been recommended to retain the vascularity of the skin flap. Intraoperative use of a femoral distractor and indirect reduction techniques decrease the amount of stripping required to obtain reduction. The use of a precontoured plate assists in both reducing and internally fixing the fracture through more limited approaches. The wound closes more easily if small, low-profile implants are used.

Alternate approaches have been described and are now frequently used. The best approach is based on the fracture pattern and surgeon preference. The anterolateral tibia can be accessed through a lateral or anterolateral approach and specially countered plates are now available which have been designed for the anterolateral tibia. A posterolateral approach has been described and may have particular utility for posterior fracture patterns. This approach has a significant complication rate including infections and non-unions and it is recommended that it is not used for all fracture patterns. Percutaneous plating has been reported for pilon fractures. The easiest access to the tibia for percutaneous plating is the anteromedial surface. Through a small incision over the medial malleolus the plate is slid subcutaneously and fixed with proximal screws placed through stab wounds. A high secondary intervention rate has been reported indicated that limited approach plating does not guarantee healing in all these fractures.

Several methods of definitive external fixation have been advocated to decrease the complications associated with plates. These techniques all use one or more of three methods to reduce wound complications: limited surgical approaches to the injured area; limiting bulky internal implants; or stabilization that bridges the area of soft tissue injury. There are a variety of different frames and application techniques.

A fixator body spanning the ankle may be constructed using any of several different components and frame constructs including medial monolateral frames, delta frames, and small pin circular fixators. One technique spans the ankle but preserves ankle motion through an articulated hinge. These frames are applied as the first step in the procedure, distracted and the provisional reduction is assessed with fluoroscopic image intensification. The articular surface is reduced using percutaneous and indirect techniques. The fracture fragments are stabilized with small fragment or cannulated screws, often placed percutaneously. Plates are never used; the fixator provides axial stability. Grafting is rarely utilized.

Postoperatively the hinge is initially locked, but can be released during the postoperative course so the ankle moves with the fixator still in place. One study showed no advantage of early movement through the hinge over a rigidly locked hinge for 8 weeks. Partial weight bearing usually begins by 4–6 weeks postinjury. The average time until the frame is removed is 3 months.

External fixation which does not cross the ankle must obtain purchase in the bottom of the tibia. A variety of frame constructs have been utilized, most of which use tensioned wires attached to a ring for distal fixation. The ankle is free which preserves the possibility for ankle movements. The fibula, if broken, is stabilized with a one-third tubular plate and lag screws through a posterolateral incision. Through an incision over the major fracture line the articular surface is reduced and secured with lag screws. The reconstructed metaphysis and articular surface are secured to a semi-circular ring with tensioned wires. The tensioned wire and ring construct is connected to a fixator body which spans the fracture and connects to the diaphysis with standard 5.0-mm half pins. A similar technique has been described utilizing pin fixators. The Ilizarov technique has frame modularity that allows the foot to be immobilized with a foot ring that can be removed at a time post injury dictated by the injury and other factors. Satisfactory results have been reported by many authors.

The most comminuted fractures and partial articular fractures are not amenable to this technique, since stable fixation of the distal tibia is not possible.

The ankle should be splinted in the neutral position. The length of time for non-weight bearing must be tailored to the individual, the type of fixation, the characteristics of the fracture, and the personality of the patient.

Interpreting the results of treatment of tibial plafond fractures is difficult at best. Recent studies incorporate patient perception of their outcome and have utilized validated outcome measuring tools. These studies have shown that these injuries have a profound effect on patient’s general health status and result in long-term ankle pain and dysfunction. These results have been found in patients treated with plates, external fixators, and with both plates and fixators. Patients in the second 5 years after their injury still have decreased general health status. Better outcomes have been found in patients with college education and poorer outcomes in work related injuries.

Beginning in the late 1960s and early 1970s good results with open reduction and internal fixation were reported with 75–90% good or excellent clinical results and few complications. In contrast with these good results, there were a number of series which reported dismal results with open reduction and internal fixation. Most authors attributed their bad results, at least in part, to the higher number of ‘high-energy’ injuries in their patient groups. The high complication rates have led to modifications of techniques and in particular the practice of delays to definitive surgery to allow soft tissue recovery and the use of temporary spanning external fixation. Recent evidence indicates that the safety profile for treating these fractures with plates has improved significantly and current techniques are as safe as external fixation.

Several authors have reported the results of treating open and severely comminuted plafond fractures with external fixators that spanned the ankle and in general, the results have been acceptable with 30–50% good or excellent and 10–25% poor outcomes. More importantly, in these injuries which were selected for their severity, all major complications were avoided. There were no infections or skin sloughs and only occasional minor pin or wire tract problems. Similar results have been reported when hybrid external fixators were used to treat selected tibial plafond fractures. Good or excellent results were obtained in 50–70% of cases treated. Complications were few and primarily related to pin sites, although each series had at least one deep infection or osteomyelitis.

In a prospective study of 49 displaced fractures of the tibial plafond managed using an articulated hinge fixator there was no tibial wound infections or osteomyelitis. At 2-year follow-up, 60% of the patients rated their result as excellent or satisfactory, 30% fair, and 10% were unsatisfied with the result.

In the most severe injuries, a substantial percentage (25–50%) of patients will continue to have pain or impaired function.

There have been several comparative trials between external and internal fixation techniques. Higher rates of complication have been observed in patients treated with open reduction and internal fixation when compared to those treated with external fixation and limited open reduction and internal fixation. On the other hand, better outcomes have been identified in patients treated with plate fixation. It has been recommended that treatment should be based on the severity of the soft tissue injury with more severe injuries favouring external fixation.

The conclusions that can most readily be drawn from these studies are that both external fixation and open reduction and internal fixation can yield reasonable outcomes. Complications must be avoided. Regardless of the treatment method there is a subset of patients with severe injuries who have a poor outcome despite proper treatment that avoids complications and most patients continue to have some ankle symptoms. Table 12.58.1 summarizes the relative advantages and disadvantages of the current techniques that are most commonly utilized.

Postoperative complications may be divided into early and late by time of onset. Wound breakdown leading to osteomyelitis is the most troublesome, and an all too common early complication of tibial plafond fractures treated operatively. The incidence is quite variable ranging from none to 55%. The evidence indicates that the rate correlates with the severity of the injury and the operative technique (Table 12.58.2).

The high rate of infection is related to the tenuous soft tissue envelope about the distal tibia, which has inherent poor vascularity. Severe soft tissue damage results from the energy released by the fracture. This causes swelling and interstitial oedema resulting in relative tissue ischaemia. Surgical dissection, soft tissue stripping, and the use of large implants often tips the scales, resulting in the progression to skin slough, wound breakdown, and osteomyelitis. The best treatment is prevention which can be accomplished by delaying surgery until the initial swelling and oedema have diminished, using small implants, performing indirect reduction techniques and stabilizing with external fixation at least temporarily.

Once faced with wound breakdown and infection, treatment must be aggressive. All nonviable tissue must be debrided, loose hardware removed, and the fracture stabilized with an external fixator. A prolonged course of intravenous antibiotics is required. Free tissue transfer for soft tissue coverage is routinely necessary. Despite these aggressive measures, a long difficult treatment course may still result in arthrodesis or amputation.

The primary late complications are non-union, malunion, and post-traumatic arthrosis. The incidence of non-union and malunion has been reported to be as high as 18% and 42% respectively. Some authors have concluded that non-unions are not complications, but rather an expected outcome in a certain percentage of fractures. Aseptic non-unions may be treated with bone grafts and/or skeletal stabilization with a high degree of success. Non-unions complicated by infection pose a much greater problem. Treatment is prolonged and expensive often requiring multiple procedures with technically demanding techniques. Amputation may be required.

Post-traumatic arthrosis is a frequent sequelae of these severe injuries (54%). One study at 5–11 years of follow-up had fairly high-grade arthrosis in 26 out of 36 ankles studied. The relative role of the damage inflicted at the time of injury versus incomplete reduction is unclear. Radiographic arthrosis, or its absence, does not correlate well with clinical measures of outcome or patient satisfaction.

Treatment of arthrosis centres around symptomatic relief with non-steroidal anti-inflammatory drugs, braces, and shoe modifications. Once conservative treatment has been exhausted, arthrodesis is a reliable option for pain relief. Ankle fusion may become exceedingly difficult if early postoperative complications have resulted in infection, nonunion, or bone loss.

The shortcomings seen in the current literature point out where future investigation and advancement is warranted. The inability to classify these fractures reliably and reproducibly makes comparison between any two series of patients extremely difficult. Comparison is further hampered by the multitude of scales used to measure outcome parameters. In order to become better at predicting the factors that are responsible for patient outcome, there needs to be some consensus on how to measure outcome. This problem is magnified by the relative rarity of this fracture, which ensures that no single surgeon or facility treats enough of these injuries to perform multiarmed studies comparing different treatment options. A goal of the future is to aim to decrease the incidence of complications and late sequelae of these injuries. Further advances in imaging such as intraoperative three-dimensional imaging may increase the use and utility of limited approaches.