Open Reduction and Internal Fixation of the Ankle
Graham Linck, Danny Arora, Robert Donatelli, Will Hall, Brian E. Prell and Richard D. Ferkel
Introduction
The treatment of ankle fractures dates back to antiquity. Evidence of healed ankle fractures has been noted in the remains of mummies from ancient Egypt.1 Hippocrates recommended that closed fractures be reduced by traction of the foot, but few other advances in the understanding and treatment of ankle fractures were made until the middle of the eighteenth century.2–4 Operative treatment of ankle fractures was popularized by Lambotte5 and Danis6; the AO group began a systematic study of fracture treatment in 1958.7–9 Since these original investigators, significant progress has been made in the treatment of ankle fractures.
Much of the current understanding of the mechanism of ankle fractures has developed from the work of Lauge-Hansen.4 In his system, the position of the foot (pronation or supination) at the time of the injury is described first and the direction of the deforming force is described second. Ankle fractures currently are classified most commonly by two systems: Lauge-Hansen4 and Danis-Weber10,11 (Fig. 29-1). The latter system is based on the location of the fracture of the fibula: infrasyndesmotic, transsyndesmotic, and suprasyndesmotic. Fractures also are classified by the number of bones that are affected—that is, a bimalleolar fracture involves injury to both medial and lateral malleoli, whereas a trimalleolar fracture indicates that the medial, lateral, and posterior malleoli have all been fractured.
An ankle fracture is a debilitating injury, especially if the fracture is unstable. The treatment of choice for an unstable ankle fracture is open reduction and internal fixation (ORIF). Surgical treatment of a displaced, unstable ankle fracture centers on anatomic restoration of the bony and ligamentous structures that surround the joint. As technology and surgical techniques have advanced, so have the outcomes for ORIF.12–14
Surgical Indications and Considerations
Ankle fractures can be treated conservatively if the ankle mortise remains stable. The medial clear space (space between medial malleolus and talus) or lateral clear space (space between lateral malleolus and talus) must measure less than 3 mm on a mortise radiographic view, or less than 5 mm on a stress radiographic view. It is important to ensure that the talus is well reduced beneath the tibia plafond and not subluxated forward or backward. The following specific injuries are indications for conservative treatment: isolated nondisplaced medial malleolar fracture or tip avulsion fracture, isolated lateral malleolar fracture with less than 3 mm displacement and no talar shift, and a posterior malleolar fracture with less than 25% joint involvement or less than 2-mm stepoff. Conservative management usually entails immobilization in a short-leg cast or boot, which extends to the tips of the toes with the foot in an appropriate position for the type of fracture deformity. Any fracture of the ankle with a residual talar tilt or subluxation, in which the ankle mortise is not anatomically reduced, warrants surgical fixation.
In general, ORIF should be performed on all patients, regardless of age, gender, activity level, or vocation, as long as they are healthy enough to undergo the procedure. However, exceptions do exist, including paraplegics and quadriplegics, and patients who are nonambulatory and lack sensation to the lower extremities.
Preoperative variables that predict a successful outcome include an otherwise healthy patient who is well motivated to recover after surgery. Systemic diseases such as osteoporosis, diabetes, peripheral vascular disease, alcoholism, and tobacco abuse can all affect the ultimate outcome of surgery. These variables affect wound healing, as well as the healing of the fracture itself.
Surgical Procedures
Patient Evaluation
It is important to get a history on the mechanism of injury, and if possible, the position of the ankle, as well as the direction of force. This will not always be possible, because most patients will only be able to describe a twisting or rolling type of injury. Completing your history with current medical comorbidities and social habits is necessary for patient outcomes. Physical examination includes inspection, palpation, and neurovascular examination. It is crucial to note any gross deformity, which may indicate possible dislocation, and would necessitate early closed reduction and splinting, as well as any wounds around the ankle, which may indicate an open fracture, and would require emergent surgical irrigation and débridement.
A careful preoperative assessment of not only the patient’s health, but also the fracture and the patient’s swelling and skin tension, is important to a successful outcome. In some cases surgery may have to be delayed for as long as 14 days to allow swelling to resolve so the skin can be closed at the end of surgery without a wound slough. Recently, a foot and ankle pump device has been used to reduce swelling rapidly to permit earlier surgery and fewer complications.
Initially, patients may be too swollen to wear a cast. In this instance a bulky dressing with cast padding and bias type of compression wrap is applied with a posterior splint. The patient remains non–weight bearing with crutches and elevates the injured ankle above the heart to promote reduction of swelling.
Surgical Technique
The currently accepted method for fracture ORIF is the AO (Arbeitsgemeinschaft für Osteosynthesefragen, or Association for the Study of Internal Fixation) technique developed in Switzerland. This technique emphasizes the use of plates, screws, and wires as needed to achieve rigid fixation.
Four criteria must be fulfilled to achieve the best possible functional results in the treatment of ankle fractures:
1 Dislocations and fractures should be reduced as soon as possible.
2 All joint surfaces must be precisely reconstituted.
3 Reduction of the fracture must be maintained during the period of healing.
4 Motion of the joint should be instituted as early as possible.
Anesthesia and Positioning
The patient is taken to the operating room and a popliteal block is done to help control postoperative pain. General or epidural anesthesia is administered. Prophylactic antibiotics are given, and a fluoroscopy table is used.
The patient is usually placed supine with a bump under the ipsilateral hip to ease the access to the lateral ankle. A pneumatic tourniquet can be applied to the proximal ipsilateral thigh and used if required. The affected limb is prepped and draped in a sterile fashion. The prone position may be used in rare instances where a posterolateral approach would be required to allow access to the posterior malleolus.
Procedure
Recent research at the Southern California Orthopedic Institute indicates that a high percentage of patients have intraarticular pathology associated with ankle fractures.13 Almost 75% of patients with displaced ankle fractures have an osteochondral lesion of the talus that is not evident on preoperative x-ray films and can only be seen on arthroscopy before ORIF. On the basis of these results and Lantz’s research8 (which found a 49% incidence of injuries to the talar dome articular cartilage in isolated malleolar fractures), the authors recommend arthroscopy before ORIF of all ankle fractures. This approach is also supported by Hintermann’s study15 that showed a 79% incidence of osteochondral lesions of the talus with an ankle fracture.
The arthroscopic evaluation is done as described in Chapter 30. All intraarticular pathology is documented and appropriately treated. The surgeon must examine carefully for osteochondral lesions of the talus, tears of the deltoid, anterior talofibular and syndesmotic ligaments, and dislocations of the posterior tibial tendon, which may impede fracture reduction. Some fractures can be reduced and internally fixated by arthroscopic means alone.16 A typical example is a patient with a fracture of the medial malleolus that was débrided arthroscopically and fixated percutaneously with two cannulated screws (Fig. 29-2). We have also had good long-term results treating Tillaux fractures in an arthroscopic manner. After the arthroscopic portion of the procedure is completed, if the fracture is not amenable to all-arthroscopic reduction, the ankle is prepared and draped again, gloves are changed, and new sterile instruments are used.
Incisions are made over the lateral, medial, or posterior malleolus, depending on the nature of the fractures. When a fracture apparently involves only the medial malleolus, the surgeon should search for an injury to the syndesmosis with subsequent tearing of the interosseous membrane, which may result in a high fibular fracture. This type of fracture, which also is known as a Maisonneuve type of fracture, could even occur at the fibular head and may be missed if the surgeon is not diligent. In this instance, the medial malleolar fracture is reduced anatomically, usually with two screws inserted proximally through a small incision from the tip of the medial malleolus. The deltoid ligament is split in line with its fibers, and the two screws are inserted parallel to each other under fluoroscopic control. If the syndesmosis and interosseous membrane have been torn and are unstable, one or two syndesmotic screw(s) are inserted through the fibula and tibia, exiting the medial border of the tibia with the foot in dorsiflexion. The screw(s) are not placed with compression because compressing the syndesmosis restricts motion postoperatively.
When a Weber B fracture occurs with disruption of the deltoid, syndesmosis, and interosseous membrane, anatomic reduction of the medial and lateral clear spaces is critical (Fig. 29-3). After arthroscopically débriding the ankle and cleaning out the torn ligaments, ORIF is performed.
The surgeon makes an incision over the fracture site and extends it proximally and distally on the fibula. Dissection is carried down to the periosteum and the fracture site. Care is taken to identify the superficial peroneal nerve, which crosses the field approximately 7 cm proximal to the distal tip of the fibula. The fracture is exposed and the periosteum is elevated with sharp dissection (Fig. 29-4). The surgeon uses a curette to remove the hematoma and applies reduction clamps to assist in reducing the fracture. Reduction of the fracture usually also requires traction and rotation of the foot and ankle (Fig. 29-5). When anatomic reduction has been achieved, frequently one or two lag screws are used to provide interfragmentary compression across the fracture site. After this is accomplished, an appropriately sized plate is centered over the fracture site and stabilized with screws.
One or two syndesmosis screws or a screw and tightrope are then inserted to reduce the ankle, and the reduction is checked under fluoroscopy (Fig. 29-6). Postoperative radiographs are taken to verify anatomic reduction of the fractures and syndesmosis, and appropriate positioning of the screws and plate (Fig. 29-7).
When both the medial and lateral malleoli have been fractured, the lateral malleolus is approached first (Fig. 29-8). An incision is then made over the medial malleolus as previously described, the fracture site is exposed, the hematoma is removed, and the fracture is reduced. The surgeon inserts one or two screws. Postoperative x-ray films demonstrate anatomic reduction of the fractures with good position of the plate and screws (Fig. 29-9).
In ORIF of a trimalleolar fracture, the lateral and medial malleoli are addressed as previously mentioned. Using the fluoroscope, the surgeon then reduces the posterior malleolar fracture by manipulating the fragment into place and making a small incision along the anterolateral aspect of the distal tibia. Two guide pins are inserted to reduce the fragment and one or two cannulated screws are inserted from anterior to posterior to hold the posterior malleolar fragment in place. In general, posterior malleolar fracture fragments do not require internal fixation if they involve less than 25% of the articular surface. If the posterior malleolus needs to be addressed directly, a posterolateral approach can be used.
Postoperative Plan
After surgery the patient is splinted in a well-padded short-leg cast in the neutral position; the cast is split in the recovery room to allow for swelling. Patients are asked to keep the limb elevated as much as possible for the first postoperative week. The procedure can be done on an outpatient basis if the pain level is not too severe, but in some instances the patient may be required to stay 1 or 2 days in the hospital. After discharge the patient is non–weight bearing on crutches for at least 4 weeks. The cast is changed at 1 week after surgery, the wound is inspected, and all new dressings are applied. At 2 weeks after surgery, the stitches are removed and a new short-leg cast is applied for 2 additional weeks. At 4 weeks after surgery, another short-leg cast is applied and the patient starts partial weight bearing, gradually increasing to full weight bearing without crutches. After the fracture has healed, the patient can wear a supportive brace and start pool and then land physical therapy. In patients with stable, reliable fixation, early motion can sometimes be initiated after the third or fourth postoperative week to facilitate early return of motion and strength.17 Patients are restricted from operating an automobile for 9 weeks following right-sided ankle fractures.
If a syndesmosis screw or screws were inserted during fixation, the patient must be non–weight bearing for 6 to 8 weeks. The screw(s) is removed at 12 to 16 weeks postoperatively, since it can break with weight bearing if left in place. Physical therapy is started 6 to 8 weeks after surgery. After the screw(s) is removed, the patient can be more aggressive with physical therapy and weight-bearing activities.
Surgical Outcomes
A successful outcome is defined as a fully healed fracture, with the patient achieving near full or complete range of motion (ROM) with normal strength and function.9 Function is defined differently for each patient—an athlete’s function is different from that of a sedentary, elderly patient. Several different grading systems, including subjective, objective, and functional data, are used to evaluate ankle fracture results. However, ankle fracture results are difficult to compare because of the multitude of fracture patterns and different circumstances of treatment. Results can be affected by many things, including severity and type of injury, associated intraarticular problems, preexisting arthritis,3 age and reliability of the patient, quality of the bone, and other site injuries. Finally, it should be noted that there is a potential for superficial nerve injury after surgical repair, as well as syndesmosis instability.18
Younger age, male sex, absence of diabetes, and a lower American Society of Anesthesia class are predictive of a good functional recovery at 1 year following ankle fracture surgery.11 Anand and Klenarman19 report that, in a sample of 80 patients older than 60 years, 88.5% were satisfied with their postoperative outcome. Ankle fractures are the fourth most common fracture in those older than 65 years and usually are the result of significant trauma.12 Recent studies have not demonstrated any age-related risks to surgery beyond those posed by other comorbidities.14,20 Therefore, the criteria for surgery should not be different for elderly patients than for younger individuals.
Postoperative Considerations
In patients with stable, reliable fixation, sometimes early motion can be initiated after the third or fourth postoperative week to facilitate early return of motion and strength.17 Early motion and exercise have been found to have beneficial effects following ankle ORIF. Patients have demonstrated decreased activity/functional restrictions, decreased pain, and improved ankle range of motion with early mobility. However, a higher rate of adverse events following ankle ORIF was associated with early exercise/mobility so care must be taken by both the therapist and patient to not overstress healing tissues.21
When a syndesmosis screw has been inserted, the patient must be non–weight bearing for 6 to 8 weeks; the screw is removed at 10 to 12 weeks postoperatively. The screw will break with weight bearing if it is left in place. Physical therapy is started 6 to 8 weeks after surgery. After the screw is removed, the patient can be full weight bearing and initiate physical therapy.
Complications
Minor complications include incidence of 4% to 5% wound problems (epidermolysis and superficial infection) and peroneal tendinitis with painful hardware. Major problems include nonunion, hardware failure, 1% to 2% deep infections (up to 20% in diabetic patients with peripheral neuropathy), posttraumatic arthritis, and compartment syndrome. Patients who have any condition (i.e., diabetes, peripheral artery disease) that might compromise circulation in the distal extremities are at an increased risk for complications relating to wound healing and closure.22
Therapy Guidelines for Rehabilitation
The physical therapist normally evaluates the patient approximately 6 weeks after surgery. In most cases, the patient has been in a cast for those 6 weeks and has had partial weight-bearing status between 2 and 4 weeks. Studies have reported that clinical outcomes may be improved in patients with trimalleolar fractures who have full weight-bearing status in an ankle orthosis between 2 to 4 weeks after surgery.23 A recent systematic review article evaluated nine randomized control studies that compared early motion of the ankle with 6 weeks of cast immobilization and found that early mobility is associated with quicker return to work and improved ankle range of motion after 12 weeks. However, other article’s authors found that early motion was associated with increased risk of wound infection.23,24 Some authors also suggest early active range of motion (AROM) for plantar flexion and dorsiflexion as soon as the surgical incision has healed.24,25 For those patients who are having issues with wound healing, a number of new technologies have been developed to try to accelerate wound healing, such as hyperbaric oxygen therapy, low level laser therapy, nano/microcurrent technology, and infrared light.22,26–28
Evaluation
The initial evaluation establishes the baseline deficits from which further goals and treatment are formulated (Box 29-1). AROM and passive range of motion (PROM) are assessed within the patient’s tolerance. ROM is a primary limitation noted at the initial evaluation. Joint effusion and soft tissue edema are evaluated as well using either a “figure 8” technique, with a standard measuring tape, or by applying volumetrics. The patient’s ambulation is assessed to determine abnormal movement patterns secondary to an antalgic gait. At this stage the patient may have acute pain and be in a fracture boot or other type of orthosis. Often, the patient may experience hardware-related pain, which may have an affect on functional outcomes.29 The physical therapist inspects and evaluates scar mobility. Joint and soft tissue mobility is assessed with an emphasis on the way restrictions limit ROM and function. After enough mineralization and calcium formation have occurred according to the physician, an assessment of the arthrokinematic movements of the ankle joint can be done. For example, posterior glide of the talus is often markedly restricted and has been correlated to restrictions in dorsiflexion and normal gait. In addition, posterior and anterior glide of the proximal and distal fibular heads have been shown to increase AROM and PROM.
