Each acute ankle injury commonly seen in the office has associated with it a mechanism by which it can be injured, trademark symptoms that the patient experiences during the injury, and a level of disability at the time of the injury and shortly after. The mechanism and symptoms point to the specific anatomical structure that is probably involved, whereas the level of disability helps determine the severity of the injury.
In this first article of a 2-part series, we focus on the evaluation and management of the 5 ankle fractures and 3 significant soft tissue ankle injuries that must be considered in the evaluation of acute ankle injuries. We also provide a systematic guide for the examination of acute ankle injuries. The Treatment of Uncomplicated Lateral Ankle Sprains will be discussed in part 2.
ACUTE ANKLE INJURIES
Roughly 85% of all acute ankle injuries are sprains,1 of which about 85% are uncomplicated, ie, involve the lateral ligaments only.2 When the examination findings are incompatible with a fracture or tendon injury (Box), results of diagnostic studies are negative, and the primary area of tenderness is anteroinferior to the lateral malleolus over the anterior talofibular and calcaneofibular ligaments (Figure 1), the diagnosis is that of an uncomplicated lateral ankle sprain.
The 5 fractures clinicians must consider are typically associated with a soft tissue injury to the ankle, most frequently an inversion injury, with the ankle in plantar flexion. In most instances, the patient can point to the fracture site as the area where he or she had the most severe pain. Each of the 5 potential fracture sites is subjected to different levels of forces during routine activities. An activity that causes minimal discomfort at one fracture site may cause greater discomfort at another fracture site, and this may result in different extents of disability for one fracture site versus another. Routinely with each of these fractures, patients are initially able to place variable amounts of weight on the ankle and often walk on it with a limp; however, with the onset of soft tissue swelling and increased generalized discomfort, their physical limitations increase.
Of the 5 fractures, 2 occur to the proximal portion of the fifth metatarsal (fractures 1 and 2) and 2 occur to the distal third of the fibula (fractures 3 and 4). These are easily detectable by palpation before the onset of soft tissue swelling. Even after the onset of significant soft tissue swelling and generalized discomfort, discrete tenderness can usually be elicited at the fracture site.
The last fracture occurs to the dome of the talus (fracture 5), which is located inside the ankle joint and is not accessible to detection by palpation. In addition, because of the curvature of the talar dome, the fracture is often not seen on radiographs unless the fracture site is conveniently located precisely in the area of the talar dome that is included on the film.
1 – Avulsion Fracture of the Base of the Fifth Metatarsal
Mechanism of injury. Inversion of the ankle with the ankle typically in plantar flexion.
Symptoms typically experienced. Symptoms are compatible with those of a routine lateral ankle sprain plus a sharp pain and/or pop at the base of the fifth metatarsal.
Extent of disability. The forces transmitted across the base of the fifth metatarsal with weight bearing are minimal. Patients are typically able to walk on the injured ankle with only slight alterations in their gait as a result of the discomfort.
Examination findings. Palpation reveals tenderness at the base of the fifth metatarsal.
Radiographic findings. Radiographs show evidence of an avulsion fragment of the base of the fifth metatarsal (Figure 2).
Management. Prevent and/or eliminate soft tissue swelling with appropriate compression, elevation, and pain-free range of motion.1 Treat the fracture symptomatically per patient. In most cases, a comfortable, yet firm, shoe is adequate. Symptomatic treatment of the fracture is followed by the patient’s participation in a comprehensive lateral ankle sprain treatment program (to be discussed in part 2). The discomfort at the fracture site dictates initiation of and progression in the treatment program.1
2 – Fracture of the Proximal Shaft of the Fifth Metatarsal (Jones Fracture)
Mechanism of injury. Most Jones fractures occur through preexisting stress fractures. The fracture may occur spontaneously with any activity that places stress on the foot, such as running, or in association with an acute injury, most commonly with an inversion injury of the ankle. Some patients relate a history of prior episodes of pain in the area from the stress fracture.
Symptoms typically experienced. The patient can experience an acute episode of sharp pain and/or a pop solely at the proximal shaft of the fifth metatarsal with any activity that places stress on the foot. When the fracture occurs with an inversion of the ankle, the patient can have symptoms compatible with a routine lateral ankle sprain (generalized lateral ankle discomfort) plus a sharp pain and/or pop in the proximal portion of the fifth metatarsal.
Extent of disability. The forces transmitted across the proximal shaft of the fifth metatarsal with weight bearing are greater than those transmitted across the base of the fifth metatarsal. Patients with a Jones fracture are characteristically able to place variable amounts of weight on the injured ankle but are forced to significantly alter their gait because of the discomfort at the fracture site.
Examination findings. Palpation reveals discrete tenderness at the proximal shaft of the fifth metatarsal.
Radiographic findings. Radiographs show evidence of a fracture of the proximal shaft of the fifth metatarsal, frequently through a preexisting stress fracture (which is diagnosed by a callus at the fracture site) (Figure 3).
Management. Management of a Jones fracture continues to be controversial. Adding to the dilemma is the classification of Jones fractures as either “acute” or “chronic” (fracture through an existing stress fracture) based on the patient’s history and radiographic findings.
Patients with an acute Jones fracture have a history of being pain-free on the lateral aspect of their foot before the episode of acute pain, whereas those with a chronic fracture have a history of recurrent pain on the lateral aspect of their foot before the episode of acute pain.
Radiographic findings in acute fractures show sharp fracture margins and no intramedullary sclerosis, whereas the findings in chronic fractures show a widened fracture line with evidence of periosteal callus compatible with a preexisting stress fracture, as shown in Figure 3. In our experience, the Jones fracture most frequently seen in athletes is the chronic or stress fracture.
Based on reported rates of nonunion of 50% to 60% with conservative management (use of non–weight-bearing cast for 6 to 8 weeks) for chronic fractures, the recommended treatment for chronic fractures is open reduction and internal fixation (ORIF).3 For the acute fracture, conservative management with a non–weight-bearing cast for 6 to 8 weeks results in reported rates of nonunion of 25% to 44%.3
The recommended treatment for acute fractures is somewhat debatable. Why is the nonathlete with an acute fracture singled out as a candidate for conservative treatment? If the typical nonathlete is somewhat overweight, out of shape, and not actively involved in an exercise activity on a regular basis, this person, solely because of the extra weight and lack of physical conditioning, could have a difficult time in a non–weight-bearing cast for 6 to 8 weeks. The question is not whether conservative management should be used but rather how to select the appropriate candidates for this type of treatment.
We feel that the patient should be presented with the 2 methods of treatment (non–weight-bearing cast for 6 to 8 weeks and ORIF) and the reported success rates of each. In the discussion of conservative management, consider the patient’s occupation, commitments outside of work, weight, physical conditioning, and even weather conditions. In addition, advise patients of the consequences of prolonged immobilization (atrophy, loss of flexibility of leg muscles, decreased range of motion of the ankle) and that the time needed to regain normal size, strength, and flexibility of the muscles and normal range of motion of the ankle could be equal to or longer than the period of immobilization.
3 – Isolated Vertical Fracture of the Distal Third of the Fibula
Mechanism of injury. Inversion of the ankle with the ankle typically in plantar flexion.
Symptoms typically experienced. Patients have symptoms compatible with a routine lateral ankle sprain plus a sharp pain of the distal third of the fibula.
Extent of disability. Although the forces placed on the leg with weight bearing are directly transmitted to the tibia, the tibia transfers a portion (about one-sixth) of this weight to the fibula through the interosseous membrane. Thus, patients with an isolated vertical fracture of the distal third of the fibula are able to walk or limp on the involved lower extremity but have a varying amount of discomfort at the fracture site. The amount of discomfort is directly related to the amount of weight placed on the involved lower extremity.
Examination findings. Palpation reveals diffuse tenderness of the distal third of the fibula.
Radiographic findings. Radiographs show evidence of a vertical fracture of the distal third of the fibula; it is not uncommon for the fracture to be evident on the mortise and lateral views only (Figure 4).
Management. Because a fracture of the distal third of the fibula can occur in association with an ankle injury that requires surgical intervention (an injury not isolated to the distal fibula), immobilization and referral to an orthopedic specialist for appropriate management is warranted. An isolated fracture of the distal third of the fibula is generally immobilized for 3 to 6 weeks. Immobilization of an acute ankle injury for even 3 weeks can result in significant atrophy and loss of flexibility of the calf muscles, along with decreased motion of the ankle. Once the fracture has healed, the patient must participate in a comprehensive lateral ankle sprain treatment program to regain normal size, strength, and flexibility of the muscles as well as normal ankle range of motion.1
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5. Stiell IG, Greenberg GH, McKnight RD, et al. A study to develop clinical decision rules for the use of radiology in acute ankle injuries. Ann Emerg Med. 1992;21:384-390.
6. Stiell IG, Greenberg GH, McKnight RD, et al. Decision rules for the use of radiology in acute ankle injuries. Refinement and prospective validation. JAMA. 1993;269:1127-1132.