4 – Epiphyseal Growth Plate Fracture
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 at the growth plate.
Extent of disability. The extent of disability is directly associated with the severity of injury to the growth plate. The patient is characteristically able to walk or limp on the injured ankle with varying amounts of increased pain at the fracture site.
Examination findings. Palpation reveals discrete tenderness of the lateral malleolus at the site of the growth plate, about 1 inch proximal to the distal tip of the malleolus.
Radiographic findings. The growth plate will be evident. Typically, no changes are noted on initial radiographs, although, in some cases, changes compatible with those seen with a Salter-Harris fracture (types I through IV) may be evident.
Management. Some primary care practitioners may feel comfortable managing Salter-Harris type I fractures (fractures limited to distal fibular epiphysis) with immobilization in a short-leg walking cast or CAM walker for 3 to 4 weeks. However, if there is any concern regarding the extent of injury to the growth plate, referral to an orthopedic specialist is warranted. 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
5 – Talar Dome Fracture
Figure 5 – Fractures of the talar dome are located on either the lateral or medial aspect of the talar dome. A fracture of the medial aspect is shown.
Mechanism of injury. Characteristically, inversion of the ankle with the ankle in plantar flexion.
Symptoms typically experienced. Patients have symptoms compatible with a routine lateral ankle sprain. Infrequently, patients may state that they felt something happen “inside their ankle.”
Extent of disability. Various areas of the talar dome are tasked with bearing the majority of forces transmitted across the ankle joint with weight-bearing activities. Thus, the extent of disability is directly related to the amount of force normally placed on the fracture site. The patient is generally able to walk or limp on the injured ankle with the amount of discomfort related to the fracture site.
Examination findings. Because the talar dome cannot be directly palpated, the findings are those typically seen with a routine lateral ankle sprain—generalized discomfort of the ankle with increased intensity of the lateral aspect.
Radiographic findings. Fractures of the talar dome primarily occur on either the posterolateral or anteromedial aspect of the talar dome. Often the fracture is not visible on radiographs because of the curvature of the talar dome and because the area of the talar dome where the fracture occurs is usually not included on routine radiographs of the ankle. When the fracture is evident on radiographs, changes are located on either the lateral or medial aspect of the talar dome (Figure 5).
Management. When a fracture is evident on initial radiographs, immobilization and referral to an orthopedic specialist is warranted. Fragments of this fracture can become loose in the joint. Loose bodies in the joint can lead to episodes of sharp pain inside the ankle accompanied by a feeling that “something is in the way.” Because the fracture is generally not evident on radiographs, a talar dome fracture becomes the working diagnosis when the patient is slow to progress during or after a comprehensive lateral ankle sprain treatment program. For instance, if the patient has persistent pain inside the ankle with or without loose-body sensations during the program or after he returns to functional activities and follow-up radiographs are negative, the working diagnosis is a talar dome fracture and referral to an orthopedic specialist for further evaluation with a bone scan or MRI is warranted.
It is important to be able to distinguish a talar dome fracture from osteochondritis dissecans, in which a portion of the talar dome loses its blood supply (Figure 6). This type of avascular necrosis usually occurs during adolescence. The resulting bony lesion may remain asymptomatic and heal uneventfully with the return of adequate blood supply to the area, or it may present with symptoms compatible with a talar dome fracture (pain inside the ankle with or without loose-body sensations). The symptoms may develop insidiously or with any acute injury to the ankle.
Figure 6 – The circular bony lesion on the medial aspect of the talar dome is consistent with osteochondritis dissecans.
Like talar dome fractures, osteochondral injury of the talus may not be evident on initial radiographs. When the lesion is evident, immobilization and orthopedic referral is appropriate. When the lesion is not evident on initial or follow-up radiographs, the symptoms and the age of the patient dictate whether an orthopedic referral for further evaluation with bone scan or MRI is warranted.
SIGNIFICANT SOFT TISSUE ANKLE INJURIES
Of all the soft tissue ankle injuries, 3 types are considered significant because of the long-term physical limitations that can result, especially when the injuries are not identified and treated appropriately initially. These injuries involve the following anatomical areas and corresponding soft tissue structures:
•Lateral aspect of the ankle: the retinacular sheath of the peroneal tendons— responsible for retaining the peroneal tendons posterior to the lateral malleoli.
•Posterior aspect of ankle: the Achilles tendon—the tendon of the gastrocnemius and soleus muscles.
•Medial aspect of the ankle: the tendon of the tibialis posterior muscle— which is located posterior to the medial malleoli and runs a course inferior and anterior to the medial malleolus to its insertion onto the navicular bone.
Because of the potential for long-term disability after injury to each of these structures, their examination during the acute ankle injury evaluation must be emphasized. By the time the patient with a significant soft tissue ankle injury is evaluated in the office, the findings on examination are usually not as discrete to the area of injury as they are when the ankle is examined immediately after the injury. However, even if soft tissue swelling prevents a definitive diagnosis by examination alone, a history that reveals the typical mechanism of injury, symptoms experienced, and level of disability at the time of the injury is usually enough to warrant early orthopedic referral.
1 – Peroneal Tendon Dislocation
Figure 7 – In plantar flexion, the line of pull of the proximal peroneal muscles along the peroneal tendons onto the distal insertion sites is practically linear (A). In forced dorsiflexion, the line of pull becomes angular (B). With a contraction of the peroneal muscles, the stress placed on the retinacular sheath may be sufficient to allow the peroneal tendons to dislocate anteriorly, as depicted by the dotted line (C). When the ankle is taken out of dorsiflexion, the peroneal tendons spontaneously reduce (D).
Mechanism of injury. Dislocation of the peroneal tendons occurs only when the stress placed on the peroneal tendon retinacular sheath is sufficient enough to cause it to either rupture or avulse from the posterolateral aspect of the lateral malleolus. When the ankle is forced into dorsiflexion with or without inversion during an acute ankle injury, the integrity of the retinacular sheath—the ability to retain the peroneal tendons posterior to the malleoli—is challenged. If the stress is sufficient, the peroneal tendons can dislocate anteriorly. When the ankle is taken out of dorsiflexion, the peroneal tendons spontaneously reduce to their normal location posterior to the lateral malleoli (Figure 7).
The mechanism of a typical uncomplicated lateral ankle sprain—inversion with the ankle in plantar flexion—does not cause the peroneal tendons to place stress on their retinacular sheath.
Symptoms typically experienced. Patients commonly say that they felt something quickly slip or pop forward over the bone on their outer ankle and then quickly slip or pop back.
Extent of disability. The disability is typically significant. Patients frequently hobble on the ball of their foot to keep the ankle in plantar flexion (this prevents them from feeling that the peroneal tendons may redislocate). Some patients may be able to walk or limp on the foot but have persistent, often intense, pain at the site of the injured retinacular sheath.
Examination findings. Because the peroneal tendons spontaneously reduce when the foot is out of the forced dorsiflexed position, distinct tenderness is limited to the area posterolateral to the lateral malleoli (where the peroneal tendon retinacular sheath is located). Patients may also have generalized pain of the peroneal tendons. The generalized tenderness of peroneal tendon dislocation differs from that of a typical lateral ankle sprain in that it more closely follows the course of the tendons posterior to the lateral malleoli. With an uncomplicated lateral ankle sprain, there is no pain over the peroneal tendons or sheath.
Radiographic findings. In most cases, radiographs are unremarkable; however, a small avulsion fracture of the posterior lateral malleolus may infrequently occur. This fragment is seen on the anterior views of the ankle only and confirms the diagnosis.
Management. Immobilization and referral to an orthopedic specialist is warranted when the diagnosis is either strongly suspected or confirmed by the history and examination. Definitive treatment (usually operative) by the orthopedic specialist is necessary to regain the integrity of the retinacular sheath. Unless the integrity of the sheath is regained, painful dislocations of the peroneal tendons can recur and severely limit the patient’s activity.
2 – Achilles Tendon Rupture
Mechanism of injury. Achilles tendon rupture may result from an acute episode of ballistic stress that is placed on the tendon during a physical activity, such as basketball, or from sudden, unexpected dorsiflexion of the ankle that occurs with a seemingly benign action, such as stepping off an unseen curb. Although usually considered an injury of the younger athlete, Achilles tendon rupture is common in both athletic and nonathletic persons 35 years and older.
Symptoms typically experienced. Patients usually feel a sharp pain and/or pop in the back of the ankle at the time of the rupture.
Extent of disability. The extent of disability is significant, although the pain following the acute painful rupture may be minimal. The patient can usually walk or limp on the injured ankle but walks flatfooted with the foot externally rotated to eliminate the toe-off phase of the gait, which requires an intact Achilles tendon complex.