33 Ankle Fractures: Open Reduction Internal Fixation
33.Ankle Fractures: Open Reduction Internal Fixation
David J. HakMark A. Lee
Ankle fractures are among the most common orthopedic injuries. Nondisplaced fractures can almost always be successfully treated nonoperatively with close follow-up. Most displaced bimalleolar fractures benefit from operative reduction and fixation if no surgical contraindications exist.
Certain displaced-ankle fractures can be treated with closed reduction, and if successful, carefully followed to union with nonoperative treatment. Isolated, distal, fibula fractures without mortise widening or talar shift can usually be successfully managed nonoperatively if the fibular displacement is less than 2 mm. These patients must be differentiated from individuals who also have an obvious or occult injury to the medial side of the ankle. While the decision for operative versus nonoperative treatment is frequently clear, for a group of patients, the treatment decision is more difficult; for these patients, reduction may be borderline acceptable or follow-up x-rays suggest some loss of reduction.
Two classification systems of ankle fractures are commonly used. Lauge-Hansen described a classification based on the foot position (supination or pronation) at the time of injury and the direction of the injury force (external rotation, adduction, or abduction) on the foot (Fig. 33.1). The Danis-Weber classification is based on the location of the fibula fracture with respect to the ankle joint. In Danis-Weber injuries, the fibula fracture is distal to the ankle joint and is usually the equivalent to Lauge-Hansen supination-adduction injuries. In Danis-Weber B injuries, the fibula fracture is at the level of the ankle joint and can be either a supination鈥揺xternal rotation or pronation-abduction injury. Type C Danis-Weber fractures are characterized by a fibula fracture proximal to the ankle joint and are usually the equivalent of the Lauge-Hansen pronation鈥揺xternal rotation injury.
Supination鈥揺xternal rotation injuries are thought to be the most common fracture pattern. In this injury, the supinated foot is subjected to an external rotation force that may cause a varying degree of soft-tissue and bony damage. The first structure to be injured is the anterior tibiofibular ligament (stage I). As the external rotation force continues, the
fibula is fractured (stage II). Further force results in rupture of the posterior tibiofibular ligament or a fracture of the posterior malleolus (stage III). Finally, the deltoid ligament is ruptured or the medial malleolus is fractured (stage IV). Because of their clinical significance, stage II injuries must be differentiated from stage IV supination鈥揺xternal rotation injuries. Stage II injuries can be managed nonoperatively because the deltoid ligament is intact, stabilizing the talus in the mortise. However, in stage IV injuries, the ankle is unstable, and surgical management is usually recommended (1).
Figure 33.1. The Danis-Weber (AO/ASIF) classification system is based on the level of the fibula fracture. The Lauge-Hansen system is based on experimentally verified injury mechanisms. Type A Danis-Weber injuries are usually Lauge-Hansen supination-adduction injuries. Type B can be either supination鈥揺xternal rotation or pronation-abduction injuries. Type C injuries are usually pronation鈥揺xternal rotation injuries.
Traditionally, medial ecchymosis and tenderness when the ankle is palpated have been used as clinical indicators for occult injury to the medial deltoid ligament. Recent studies have shown that these traditional signs are not sensitive for predicting deltoid ligament incompetence (1,2). Stress radiographs should routinely be obtained in patients with isolated fibula fractures that are classified as supination鈥揺xternal rotation injuries (Danis-Weber type B) so the physician can identify occult injury to the deltoid ligament. Several different methods for obtaining stress radiographs have been described and include the use of gravity, valgus stress, or external rotation (2,3).
We prefer a careful evaluation of high-quality plain x-rays in the absence of plaster, which may obscure important findings. Occasionally, contralateral radiographs are useful to evaluate unusual abnormalities. The physician must understand the normal radiographic landmarks and relationship of the fibula with the distal tibia. Equal medial, lateral, and superior joint space should be seen surrounding the talus on the mortise view. The position of the distal fibula with respect to the incisura should be carefully evaluated. This is measured 1 cm proximal to the tibial plafond. Specific measurements may vary depending on the ankle rotation and angle of the x-ray beam. The distance between the medial border of the fibula and the incisura should be less than 6 mm on both the anteroposterior (AP) and mortise view. On the AP view, the fibula should overlap the tibia by 6 mm, or 42 % of the fibular width, and there should be at least 1 mm of overlap between the fibula and tibia on the mortise view. Finally, the length of the fibula is assessed by evaluating the talocrural angle, which on average should measure 83 卤4 degrees and can be compared with the contralateral ankle (Fig. 33.2). In addition, fibular shortening will lead to incongruity in a line drawn along the tibial plafond and the medial border of the distal fibula (Fig. 33.3).
Figure 33.2. Radiographic projection of fibula on tibia in standard AP radiograph. When measured 1-cm proximal to the ankle joint, the distance between the medial border of the fibula and the incisura should be less than 6 mm on any view. On the AP view, the fibula should generally overlap the tibia (shaded area) by greater than 6 mm or more than 42% of the fibular width; however, individual variation and beam angle may effect individual measurements. There should be more than 1 mm of overlap of the tibia and fibula on any view.
One of the major goals of ankle fracture management, whether operative or nonoperative, is to maintain anatomic reduction of the tibiotalar joint. Lateral displacement of the talus will reduce ankle joint contact, resulting in joint-contact stress alterations that may predispose the patient to posttraumatic osteoarthritis (4,5,6).
Figure 33.3. Normally, there is congruity in a line drawn along the tibial plafond and the medial border of the fibula. When the fibula is shorted, incongruity is observed at the junction of the tibia and fibula.
Closed reduction and splinting are the first step in fracture management. The majority of rotational ankle fractures will require little more than longitudinal traction and internal rotation reduction to be achieved. A well-padded, posterior, plaster splint with the ankle at neutral dorsiflexion will provide comfort and immobilization and allow for soft-tissue swelling. In general, immediate circumferential casting should be avoided, even if this is eventually chosen as the definitive treatment method, as ongoing swelling can lead to dangerous constriction and exacerbation of the soft-tissue injury. Edema control with judicious elevation is a well-accepted approach to early management if compromised vascular inflow is not an issue. Cryotherapy may reduce swelling and may have analgesic benefit. More recently, intermittent compression devices have been utilized to help control swelling both preoperatively and postoperatively (7,8).
Occasionally, when managing fractures with significant soft-tissue injuries or those with large, posterior, malleolar fractures that cause persistent talar subluxation, the surgeon may find that temporary external fixation is required. External fixation provides fracture and soft-tissue stability, allows for free access and easy evaluation of the soft tissues, and optimizes patient mobilization.
Many ankle fractures requiring open reduction and internal fixation can be addressed with immediate surgery. However if soft-tissue swelling is a concern, the operation is delayed and the limb is immobilized and elevated. Examination of the skin should be performed preoperatively
to insure that the soft tissues can safely permit operative treatment. This requires removal of the splint or cast prior to the induction of anesthesia. The 鈥渨rinkle sign鈥� is often used to assess the readiness of soft tissues for surgical intervention. The ankle is dorsiflexed to the neutral position and the anterior ankle skin is observed for the presence of wrinkles. Absence of wrinkles suggests excessive soft-tissue swelling and edema.
While open reduction and internal fixation (ORIF) of most ankle fractures is straightforward, care should be exercised to avoid unexpected findings. A careful review of high-quality plain radiographs (without obscuring plaster) should be performed. A preoperative plan or surgical tactic, while often neglected for this 鈥渟imple鈥� fracture, may provide mental preparation and avoid unnecessary mistakes. Forging ahead, assuming the case is a simple straightforward ankle fracture, can lead to suboptimal outcomes when unusual fracture variations are encountered.
Patients are generally positioned supine, and a general or spinal anesthetic is administered. Prophylactic intravenous antibiotics are administered prior to surgery. A first-generation cephalosporin is used unless there is an allergic contraindication, in which case an alternative antibiotic is chosen. A towel roll is placed beneath the ipsilateral buttock to provide easier access to the fibula (Fig. 33.4). As is routine, a pneumatic tourniquet is applied to the upper thigh. The leg is sterilely prepped. A sterile sheet is then placed beneath the leg to prevent inadvertent contamination of surgical gowns during the draping process. A stockinette is applied to the leg, and the leg is draped free. The toes are sealed with a plastic adhesive drape and the stockinette is removed to the midcalf.
Prone positioning may occasionally be indicated for trimalleolar ankle fractures with a large, displaced, posterior, malleolar fragment that will be fixed through a posterolateral approach. Reduction and fixation of the medial malleolus in the prone position may be easiest performed after the knee is flexed.
Figure 33.4. Before prepping and draping the patient, a roll is placed beneath the ipsilateral buttock to facilitate easier access to the fibula. A tourniquet and occlusive drape may be placed around the upper thigh.
Bony landmarks are palpated and marked. The location of the fracture can also be marked based on palpation and radiographic review. We generally perform surgery under tourniquet control to minimize blood loss, to maximize visualization, and to speed the surgical procedure. After confirming that preoperative prophylactic antibiotics have been administered, we exsanguinate the extremity with an elastic (Esmarch) bandage and inflate the tourniquet to the appropriate level.
In bimalleolar fractures, the surgeon's preference dictates whether the medial malleolus or the fibula is fixed first. In cases of osteopenia, we prefer to fix the medial malleolus first because it may aid the subsequent reduction of the fibula. Care must be exercised when using reduction clamps on osteopenic bone. Excessive pressure with reduction clamps may easily cause iatrogenic comminution of the fibula. In addition, the ankle joint can usually be visualized through the medial malleolar fracture site in most circumstances. This allows inspection of the articular surface and removal of any intra-articular debris. While joint inspection and irrigation can be performed either before or after fixation of the fibula, we often do this prior to rigid fixation of the fibula.
Medial Malleolar Fixation
Our preferred medial incision is straight and aligned with the long axis of the tibia. This incision should also be placed slightly anterior to the midcoronal axis to allow inspection of the anterior aspect of the ankle joint. Other surgeons prefer a slightly angled incision, but too much, distal, anterior angulation may make difficult the access to the screw insertion site. The saphenous vein and its accompanying saphenous nerve branches should be preserved whenever possible (Fig. 33.5).
Adequate exposure is required to ensure an anatomic reduction. This can best be confirmed by visualizing the anterior aspect of the fracture. Because of the orientation of the fracture plane, anterior or posterior malreduction may not always be appreciated when looking at the lateral surface.
Distal retraction of the medial malleolus allows irrigation and thorough inspection of the articular surface of the tibia and talus (Fig. 33.6). Any osteocartilaginous debris should be removed. Articular damage to either the tibia or talus should be noted in the operative report.
Approximately 2 mm of periosteum is excised along the edges of the fracture. A 2.5-mm drill is used to perforate the medial tibial cortex to allow anchorage of a bone tenaculum. A small, pointed, bone tenaculum can be placed on the medial malleolar-fracture fragment from anterior to posterior and used to guide the reduction. A second small or large, pointed, bone tenaculum is then used to achieve compression of the reduction. One tine is placed in the tibial metaphyseal drill hole and the other is placed around the distal aspect of the
medial malleolus. (Fig. 33.7).
Figure 33.5. A relatively straight incision is used for the medial malleolus. Excessive, distal, anterior angulation may interfere with the necessary screw-insertion angle. The saphenous vein and nerve should be visualized and protected during the medial approach to the ankle.
Figure 33.6. Retraction of the medial malleolar fragment distally allows inspection and irrigation of the ankle joint.
Figure 33.7. A pointed reduction tenaculum is used to provide provisional reduction of the medial malleolus. One tine is placed in a drill hole placed in the medial tibial metaphysis and the other tine is placed around the distal aspect of the medial malleolus. Partially threaded, cancellous, lag screws are inserted anterior and posterior to the tenaculum.
Large, one-piece, medial, malleolar fractures are usually secured with two 4.0-mm, partially threaded, cancellous screws. With the tenaculum centered on the fragment, one screw is placed anteriorly and one is placed posteriorly to the tenaculum. A scalpel is used to split the superficial deltoid ligament in line with the fibers to facilitate placement of the drill against bone. With the hind foot slightly everted, a 2.5-mm drill bit is then drilled across the fracture site in line with the long axis of the tibia. A second drill bit or Kirschner (K) wire may be placed to avoid rotational forces during the screw insertion. We routinely use a 40-mm cancellous screw because the nonthreaded portion is usually long enough so that the threads are positioned beyond the fracture site and engage the denser, distal-tibial, cancellous bone. For optimal results, the threads should be placed in the denser distal-tibial metaphysis, especially in patients with osteoporosis. A second 4.0-mm cancellous screw is then inserted parallel to the first screw.
The surgeon must match the implant size to the fracture fragment size to avoid iatrogenic comminution and malreduction. The use of 4.0-mm cancellous screws may not be advisable if the medial malleolus-fracture fragment is very small or comminuted. Other options for small-fragment fixation include the use of a single lag screw with a K wire, small diameter screws, or tension band wiring. Extra-long 2.0- and 2.7-mm screws are available; although they may not be stocked on standard sets, they are useful for very small medial-malleolar fragments. Tension band fixation is performed by inserting 1.6-mm K wires in a direction similar to the standard screw fixation. Eighteen-gauge wire or no. 5 suture is then passed around the K wires and crossed in figure-of-eight fashion around a screw placed in the tibial metaphysis. The ends of the K wires are then bent and impacted.
Vertical malleolar fractures, as occur in supination-adduction type injuries should be fixed either with horizontal screws (placed at right angles to the fracture) or with a short, low-profile, medial, buttress plate. Washers may be required in osteoporotic patients to prevent the screw from sinking through the thin metaphyseal cortex. This fracture pattern may also be associated with marginal impaction of the tibial plafond. Reduction of the tibial plafond and support with bone graft or bone graft substitute may be required prior to medial malleolar reduction (Fig. 33.8).
The fibular incision is based on the location of the fracture and the planned position of fixation. Adjustments may be needed due to associated soft-tissue abrasions or healed blisters. The fibula is generally approached through a relatively straight
incision (Fig. 33.9). Angling the distal portion of this incision slightly anteriorly will allow access to the anterolateral corner of the ankle. This will allow access to the anterolateral aspect of the ankle joint and permit fixation of a Chaput-Tillaux fragment, which is an avulsion of the anterior, inferior, tibiofibular ligament. A more posterior incision may be used if a posterior antiglide plate is planned. Care should be taken to preserve the
superficial peroneal nerve, which may cross the surgical approach at a subcutaneous or fascial level, to avoid painful neuroma formation.
Figure 33.8. Impaction of the medial, distal, tibial-articular surface may be seen in supination-adduction injuries. Following reduction, this segment may be buttressed with either local metaphyseal bone, allograft bone, or bone graft substitutes. Because of the vertical orientation of the fracture plane, the interfragmentary lag screws are usually placed parallel to the ankle joint.
Figure 33.9. A straight lateral incision may be used for fixation of the fibula. The incision may be adjusted anteriorly or posteriorly depending on the fracture patterns and the planned fixation.
The periosteum at the edges of the fracture should be elevated, but further periosteal stripping is kept to a minimum, especially in comminuted fractures. Care must be exercised when reducing the fibular fracture to avoid iatrogenic comminution. This precaution is especially critical in older patients with osteoporosis. Fracture reduction can be achieved by using one or more of the following techniques: Traction and rotation can be applied to the hind foot to assist with fracture reduction; a bone tenaculum may be attached to the distal fragment and used to manually reduce the distal fragment; the tines of a bone tenaculum may be placed at right angles to the fracture plane and used to obtain and secure the fracture reduction. Fracture reduction is usually fairly easy immediately after injury but may be more difficult in delayed cases with fibular shortening.
Simple, oblique, fibula fractures are usually reduced and fixed with an interfragmentary lag screw and a neutralization plate. Occasionally, long oblique fractures can be adequately fixed with only interfragmentary lag screws (9). While we usually use a 3.5-mm cortical screw for the lag screw fixation, in smaller fragments it is occasionally advantageous to use a smaller diameter screw, such as a 2.7-mm or 2.0-mm cortical screw (Fig. 33.10).
Figure 33.10. For oblique fibular fractures, a 3.5-mm cortical screw is placed in lag fashion perpendicular to the fracture plane.
For comminuted fibular fractures in which lag screw fixation is not feasible, plate fixation is applied in a bridging mode such that the comminuted fracture area is bypassed. For many fractures, simple one-third tibular plates are adequate, but for very distal fractures we prefer to use a bone-specific, custom, fibula plate (Zimmer, Warsaw, IN) that allows a larger number of distal screws (Fig. 33.11). As an alternative approach, a small-fragment locking plate could also be used to provide improved fixation stability in a small, distal, fracture fragment. When no bony keys are available to determine reduction, the distal fragment may be reduced to the talus provisionally with K wires. After visual and radiographic confirmation of the reduction, the surgeon can apply a plate in a bridging mode.
Figure 33.11. This fibular peri-articular plate allows placement of additional distal-screw fixation, which may be particularly useful for obtaining additional screw fixation in very distal fractures.
We usually examine and irrigate the ankle joint through the medial incision. However, in selected circumstances, visualization of the anterior ankle joint can also be performed by dissecting anterior to the fibular and retracting the soft tissues with a small right-ankle retractor (Fig. 33.12). This exposure may also be used to reduce and internally fix avulsion fractures involving the anterior tibiofibular ligament (Chaput-Tillaux fragments).
Soft tissues are handled as gently as possible throughout the procedure, especially during wound closure when excessive skin-edge manipulation with forceps can traumatize the tissue. We typically close incisions in an interrupted fashion with no. 3-0 or 4-0 nylon
sutures via an Allg枚wer-Donnatti technique. Because of the limited deep tissue, a two-layer closure is usually not feasible; however, deep absorbable sutures may help align the incision and relieve tension for the skin closure.
Figure 33.12. Exposure of the anterolateral ankle joint may be performed by dissecting anterior to the fibula and retracting soft tissues with a small right-angle retractor.
Posterior Malleolus Fixation
Clinical studies have shown that ankle fractures with posterior malleolar involvement have a higher incidence of posttraumatic osteoarthritis than do bimalleolar ankle fractures. Simulated, posterior, malleolar fractures have shown a modest increase in ankle contact stresses in static mechanical-loading studies. Development of arthrosis may also be due to associated chondral damage and joint instability. Rather than significantly increasing contact joint stress, a pronounced anterior shift in the location of the articular contact area was found in a recent study in which dynamic ankle motion was examined in a simulated, posterior, malleolus fracture (4). The authors postulated that this shift in location produced substantial loading of articular cartilage not accustomed to bearing stress and thus initiated the arthrosis.
Posterior, malleolar, fracture fragments may vary greatly in their size. Small fragments are often extra-articular. These small fragments are attached to the posterior, inferior, tibiofibular ligament and are usually adequately reduced with anatomic reduction of the fibula. However, larger, posterior, malleolar fragments may comprise a significant portion of the articular surface, and anatomic reduction is probably essential for good long-term function.
Evaluation of posterior, malleolar, fracture-fragment size is limited with plain radiographs and is better evaluated with a computed tomography (CT) scan (10). If a CT scan is unavailable, then a 50-degree external-rotation view may better allow assessment of the posterior fragment size (11,12).
The decision that the posterior malleolus needs to be fixed should ideally be made preoperatively based on the size of the fragment. Most authors recommend fixation of posterior malleolar fractures that comprise more than 25% of the articular surface. Closed reduction with dorsiflexion of the ankle and percutaneous anterior-to-posterior fixation has been described as an alternative treatment for nondisplaced or minimally displaced, posterior, malleolar fractures. However, the accuracy of this method may not always result in an anatomic position. Our preference for treatment of large, posterior, malleolar fractures requiring fixation is to reduce and stabilize these fractures prior to fixation of the fibula because the application of a plate on the fibula usually obscures lateral radiographic visualization of the articular surface. A large pointed tenaculum may be inserted posteriorly through the fibular incision. A small incision is made over the anterior tibia and blunt dissection carried down to the bone to allow placement of the anterior tine (Fig. 33.13). Minor manipulation of the fragment can be achieved with dorsiflexion of the ankle and
rotational torque of the tenaculum. Anterior to posterior fixation of the fragment is then achieved with either standard screws or cannulated screws placed through one or more percutaneous incisions.
Figure 33.13. A large bone tenaculum is placed around the fibula and can be used to manipulate and reduce the posterior malleolus. The small tenaculum in this photo is maintaining reduction of the fibula fracture.
Figure 33.14. A. This large, posterior, malleolus fragment was exposed through a posterolateral approach along the lateral border of the Achilles tendon. B. Following direct reduction of the fracture fragment, posterior-to-anterior lag-screw fixation with 4.0-mm cancellous screws and washers. After posterior malleolus fixation, fibula fixation can be achieved using a posteriorly placed antiglide plate.
For large, noncomminuted, posterior, malleolar fragments, fixation may be achieved through an open posterior approach. The patient is positioned prone and a posterolateral approach to the fragment is performed along the lateral border of the Achilles tendon (Fig. 33.14). This allows accurate fragment reduction via visualization of the fragment at the posterior tibial metaphysis. The fracture fragment is internally fixed with two or three posterior-to-anterior screws. Washers are often used to prevent penetration of the screw heads through the thin tibial cortex. In an alternative, a short, two- or three-hole, one-third, tubular plate may be applied in an antiglide mode to the posterior tibia.
For fractures in which the posterior malleolus is more medially based, or in which there is metaphyseal cortical comminution that may not provide an adequate reduction key, reduction of the posterior malleolar fragment may be obtained through the medial approach prior to reduction of the medial malleolus. This approach will allow direct visualization of the articular surface. The flexor tendons are retracted posteriorly with a small Homan retractor, and a small bone hook or pointed tenaculum is used to obtain fragment reduction. Fixation is then achieved with anterior-to-posterior lag screws inserted through small stab incisions.
Syndesmotic Assessment and Fixation
Disruption of the tibiofibular syndesmosis may occur with type-C ankle fractures; however, transsyndesmotic fixation may not be required in all cases. Anatomic reduction and stable fracture fixation may restore adequate syndesmotic stability. More distal fibula fractures secured with rigid plate fixation may offer sufficient stability to obviate the need for transsyndesmotic fixation (13,14). If the deep deltoid ligament is intact, rigid fixation of the medial malleolus will also provide an additional stabilizing force that prevents talar subluxation.
Regardless of the location of the fibula fracture and the rigidity of the fracture fixation, we recommend careful assessment of the syndesmosis in all ankle fractures. Traditionally, syndesmotic stability in ankle fractures has been assessed by pulling the fibula laterally in the coronal plane either with a clamp or bone hook (i.e., the 鈥淗ook test鈥�). The distal tibiofibular syndesmosis consists of the anterior tibiofibular, posterior tibiofibular, and the interosseous ligaments. Additional stability is provided by the interosseous membrane and the medial deltoid ligament, both of which may have been injured to varying degrees.
Rather than pulling the fibula laterally, we recommend stressing the fibula anteriorly and posteriorly in the sagittal plane. Disruption of the syndesmosis will produce significant instability of the fibula that may be best appreciated in the sagittal plane. The improved sensitivity of this testing method was recently described in a cadaveric study (15).
Several areas of controversy are contended in syndesmotic fracture fixation. These issues include screw diameter, number of screws, number of cortices engaged, timing of weight bearing, and the need and timing of screw removal.
We prefer to use a large-fragment 4.5-mm screw for syndesmotic fixation because of its increased strength and its ease of removal. However, it requires availability of an additional implant set. The larger head can be easily palpated at the time of removal and there is no risk of incorrectly removing one of the small-fragment screws. We generally engage only three cortices except in cases of severe osteopenia, in which case it may be advantageous to place a screw across the far tibial cortex to improve purchase. The use of three cortices allows some angular freedom of the screw and may prevent mechanical screw fracture. Except in cases of very proximal fibular fractures (Maissoneuve injury), we only use a single syndesmotic screw. We generally allow patients to weight bear on their syndesmotic screws after 6 weeks and plan removal of the syndesmotic screw at 3 months. This can usually been done in the office under local anesthesia.
Steps we use during placement of syndesmotic screws include the following:
Elevate the heel on a towel roll to allow the surgeon room to position the drill to direct the screw correctly. Because the fibula is located at the posterior border of the tibia, syndesmotic screws should be angled anteriorly approximately 30 degrees from the coronal axis.
Position the ankle in neutral dorsiflexion. Because the talar dome is wider anteriorly than posteriorly, fixation with the ankle plantarflexed may, in theory, overtighten the mortise.
Reduce the syndesmosis. The syndesmotic reduction can usually be held manually with light pressure, although temporary K-wire fixation may also be used. Caution should be exercised in using any type of clamp because if the clamp is not perfectly centered its use may create unappreciated malrotation or translation of the fibula.
A 3.2-mm drill hole is made approximately 2 cm above the ankle joint. This should be parallel to the ankle joint and directed anteriorly approximately 30 degrees (Fig. 33.15).
Figure 33.15. Syndesmotic fixation screws should be directed approximately 30 degrees anterior to the coronal plane.
We drill through the opposite cortex and measure the total length with a depth gauge. In most cases, we choose a screw approximately 1 cm shorter than the measured length so the far cortex is not engaged. In cases of severe osteopenia, we choose to engage the far cortex. The fibula and near cortex is then tapped with a 4.5-mm tap and the screw is inserted. Accurate reduction is then confirmed with bi-planar fluoroscopic views of plain radiographs.
In Maissoneuve fractures in which the proximal fibular fracture is not internally fixed, we manually reduce the syndesmosis and secure it provisionally with one or more K wires. After the reduction is confirmed with bi-planar fluoroscopic imaging, we place two 4.5-mm screws as described above.
We carefully scrutinize all postoperative ankle x-rays. In addition to evaluation of fracture reduction and hardware position, we look for radiographic parameters of anatomic syndesmotic reduction. With the AP and mortise views, we verify adequate tibiofibular overlap. We also examine the position of the fibula with respect to the incisura. While specific measurements may vary based on the x-ray beam ankle, on the AP view the fibula and tibia should overlap by at least 6 mm, and the distance between the medial border of the fibula and the incisura should be less than 6 mm on any view. Equivocal findings merit comparison to the contralateral-ankle stress radiographs. If there are equivocal findings following syndesmotic ORIF, then we recommend CT to evaluate proper position of the fibula within the tibial incisura. Finally the length of the fibula is assessed by evaluating the talocrural angle, which on average should measure 83 (卤4) degrees (see Fig. 33.2).
In a study of 20 patients with unstable ankle fractures who underwent ORIF, significant improvements in all domains of the SF-36 Health Survey, except for general health, were seen between 4 and 20 months after the operation. However, after 20 months their physical functioning scores remained below those of the US population norm (16).
Similar findings were reported in another study of 30 patients undergoing operative treatment of displaced Danis-Weber type-B ankle fractures. At 24 months, the authors noted significantly lower SF-36 physical function and role physical scores compared to the US norms (17).
A nonadherent dressing and sterile gauze pads are applied to the wounds and held in position with sterile cast padding. With the ankle held in neutral dorsiflexion, additional cast padding is applied followed by a short-leg, posterior, stirrup splint. The splint is maintained until the patient can comfortably dorsiflex the injured ankle and thus prevent equinus contracture. The leg is elevated postoperatively to minimize swelling. Patients with sufficient home-care assistance may be discharged directly home, but many patients require overnight observation.
Patients are seen in follow-up appointments between 7 and 14 days after surgery. The splint is removed and if adequate wound healing is evident, the sutures are removed. Radiographs are checked to confirm maintenance of reduction. Reliable patients are instructed in active ankle and subtalar range-of-motion exercises. Patients are placed in a removable short-leg orthotic.
We generally restrict weight bearing for 6 weeks postoperatively. Repeat x-rays are obtained at 6 weeks, and patient weight bearing is advanced at this time. If necessary, physical therapy is initiated to assist with regaining range of motion, proprioception, and strengthening.
Persistent dependent swelling may persist for many months and may require use of compression stockings or elastic wraps. Patients are cautioned against returning to sports until they have regained adequate strength and agility. Return to driving is left to the patient's judgment, although a recent study has shown that simulated braking time returned to normal at 9 weeks following internal fixation (1).
Some preventable complications are due to a failure to appreciate initially the complexity of the ankle fracture pattern. While many ankle fractures are simple standard fractures that can be easily fixed with anticipation of an excellent outcome, other fractures will be more complex and anatomic reduction may be difficult. The physician's failure to appreciate the size of a posterior malleolar fragment, the presence of articular impaction, or intra-articular fragments will likely predispose the patient to a suboptimal outcome (18).
Loss of motion, especially dorsiflexion, can be problematic following ankle fracture. If independent range-of-motion exercises and stretching is not rapidly successful in restoring a functional range of motion, early referral should be made to physical therapy. Rarely, a posterior, soft-tissue, capsular release along with lengthening of the Achilles and other flexor tendons may be indicated to improve severely restricted ankle dorsiflexion.
Loss of Fixation
Screw purchase is often compromised in patients with severe osteopenia. Newly developed locked-screw plate constructs may be considered to improve stability in certain circumstances. The use of injectable one-graft substitute pastes that harden in situ has been shown to improve screw purchase in patients with severe osteopenia. Insertion of intramedullary K wires to cross thread with the fibular plate screws has also been said to improve fixation in both biomechanical and clinical studies (19).
Infection and Wound Complications
Postoperative infection usually presents as wound drainage or wound breakdown with accompanying erythema. Operative debridement and culture-specific antibiotics are usually required. Because of the risk of ankle joint involvement, ankle aspiration through a noncellulitic area is also suggested. Once the infection is under control and the soft tissues are healthy, delayed tension-free closure can be performed. Tension relief using a 鈥減ie-crust鈥� technique may be helpful to obtain a tension free closure (Fig. 33.16). Small stab wounds are placed in the skin and allowed to heal by secondary intention.
The incidence of posttraumatic arthritis following ankle fractures is not known. While it is generally thought to be low, few reported long-term follow-up studies are available. A higher percentage of poorer results have been seen with studies reporting relatively long-term follow-up (20). Posttraumatic arthritis can be anticipated in cases where there has been significant articular cartilage damage, such as may seen in supination-adduction fracture patterns, and where malreduction is followed by talar subluxation. Factors reported to be associated with the development of posttraumatic arthritis include a shortened fibula, a widened ankle mortise, and Danis-Weber type-B fractures.
Nonunion following ankle fractures are uncommon. Patients with nonunion usually present with persistent pain localized to the fracture site. Shortening and malrotation of the fibula can frequently occur after both operative and nonoperative management of
malleolar fractures (21,22). This can lead to ankle valgus and disruption of talocrural mechanics. Various lengthening osteotomies for the fibula that can restore normal joint mechanics and alleviate clinical symptoms have been described (23).
Figure 33.16. A. Breakdown of distal fibula wound with exposed screw head. B. After excision of the affected area, the pie-crust technique was used to permit skin closure. C. The small pie-crust stab wounds heal by secondary intention.
Hardware Prominence and Pain
Hardware prominence is fairly common in thin individuals following ankle fracture fixation due to the subcutaneous location of the hardware (24). This most commonly involves lateral fibular plates and screws. Symptomatic relief can usually be obtained with outpatient hardware removal after the fracture is adequately healed. We normally encourage patients to wait 1 year from the time of surgery before removing their hardware. Patients are permitted full weight bearing after hardware removal but are cautioned against activities that could cause significant torsional force for 6 to 12 weeks following hardware removal.
In one study of 126 patients, 31% had lateral pain overlying their fracture hardware. Of the 22 patients with hardware-related pain who had undergone hardware removal, only one half had improvement in their lateral ankle pain following hardware removal. In addition, functional outcome scores were poorer for patients with pain overlying lateral-ankle hardware than in those with no pain at this location; this poorer outcome seems to be independent of whether the hardware had been removed.
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