Athletic Soft Tissue Injuries of the Foot and Ankle

Historical Perspective

Herodotus of Halicarnassus records the first ankle sprain in sports in his historical writings from the time of the Greek and Persian empires when King Darius I of Persia twisted his ankle while hunting. Herodotus also documents the first use of exercise as a treatment in Western medicine. This is not surprising, since track and field events were an integral part of the early religious festivals held at Olympia, Delphi, Nemea, and Corinth, and the first date recorded on a Western calendar was a sports event, the Olympiad of 776 bc. Paré was the first to point out that exercise of the limbs was essential to recovery after treatment of a fracture. For the physician treating an athlete, this approach reflects the essence of sports medicine.

Epidemiology

Sports participation has become a fundamental characteristic of American society. A survey of a few of the most popular sports reveals that about nearly 90 million people play football, soccer, baseball, basketball, and softball combined. While numbers for football have been decreasing over the past 5 years, the overall number of player participation continues to increase. Injuries to the lower extremities constitute the majority of injuries for most sports ( Fig. 36-2 ). This is particularly true for the running, jumping, and kicking sports. Table 36-1 provides a look at injury rates calculated for the foot and ankle from studies done for various sports. As of 2018 according to the National Federation of State High School Associations, yearly sports participation at the high school level had increased each year for 30 consecutive years, reaching its peak in 2018 of nearly 8 million participants.

All sports and recreational activities carry an inherent risk of injury. It is a natural consequence of pushing against the body's physical limitations and being involved in challenging competition. Nevertheless, one of the goals of sports medicine is to reduce the health risks of athletic participation by recognizing and minimizing the risk factors. From the vantage point of careful epidemiologic study, it is possible to identify and quantify risk along with the incidence and prevalence of injury for a given set of conditions.

To analyze epidemiologic data properly, it is critical that the population being analyzed is assiduously defined. Many studies of athletic injuries that have engendered prejudicial thinking about the causes for injuries are flawed because of their methodology. Contemporary medicine favors evidence-based health care and outcomes-based research. Unfortunately, the literature in sports medicine, orthopaedics, and even medicine in general is overwhelmingly derived from reports and retrospective case series where the level of evidence is less than ideal. Many of these case series report an injury rate, but they often fail to accurately define the population at risk for injury. A good example is the prevalent idea that runners who pronate (or more precisely, overpronate) are at a greater risk for a running injury. The 1978 article by James et al fostered this idea by noting that 58% of their 180 patients had a pronated foot configuration. This study does not take into consideration the total number of people in the running population from whom this select group was derived who also pronate but do not have an injury problem.

Another problem with many studies is failure to provide an accurate definition of the factor being analyzed. In sports injury studies, this is often related to variations in the definition of what constitutes an injury from one study to the next. For example, it is difficult to compare ankle injury studies such as Rowe's, where an injury is defined as anything that causes an athlete to require medical attention and lose time from participation, with studies with much stricter definitions and classifications, such as Torg and Quedenfeld's. The comparison difficulties are magnified when the comparison extends across sports and across levels of participation, because an injury to a peewee football participant might have no relationship to what a professional rugby player considers an injury.

Finally, the homogeneity of the population being studied is important. This relates to such considerations as exposure to injury, age differences, gender differences, preexisting injury, and other confounding variables that might significantly influence injuries. For example, the third-string tackle who seldom plays in games has a much lower risk for a turf toe injury than the starting running back.

With these factors in mind, one can appreciate the differences between studies and the number of variables involved. The risk factors for injury can be divided into intrinsic and extrinsic varieties. The athlete's physical and personality traits constitute the intrinsic factors, and the training techniques, playing environment, and equipment are among the extrinsic risk factors. In this regard, several studies have demonstrated that weekly running mileage is the most critical factor in the risk of injury in the running population. When weekly mileage surpasses 64 km (40 miles), the risk of injury increases logarithmically. Other significant risk factors in runners include a history of injury in the recent past, having run for 3 years or less, and a recent major change in the training regimen or environment.

Etiologic Factors

Preventative sports medicine has begun to play a larger role over the past 2 decades. This is based upon a better understanding of the intrinsic and extrinsic factors that have a potential role in the cause of injury to the athlete. With a better understanding of these factors, we can tailor processes that allow interventions that can reduce or eliminate risk factors, thereby lowering the risk of injury. Examples of such intervention include rule changes in football to eliminate the “crack-back block,” “spearing,” and “head-to-head” contact, as well as improved generations of synthetic grass and underpadding brought about by research into the relationship between artificial turf and injury. Janda et al found that 70% of softball injuries were related to stationary bases, and 56% of these injuries were to the foot and ankle. By substituting breakaway bases, they demonstrated a reduction in injuries from 1 in 14 games to 1 in 317 games ( Fig. 36-3 ). Bahr and Bahr have similarly demonstrated the possibility of reducing ankle injuries in volleyball through an injury awareness program and training with a balance board. These types of studies can clearly affect the health of athletes, particularly their feet and ankles.

Although it is beyond the scope of this section to discuss all the potential risk factors involved in athletic injuries to the foot and ankle, a few of the more important ones are investigated. The factors most often mentioned in association with foot and ankle injuries in sports include anatomic or biomechanical abnormalities, lack of flexibility, poor muscle strength, muscle imbalance, shoes and orthoses, and the playing surface.

Biomechanical Abnormalities

Certain underlying anatomic conditions are often related to athletic injuries. Many runners and coaches place abnormal foot biomechanics in this category in the belief that the runner with excessive pronation has an innately higher risk for sustaining a running-related injury. A prospective cohort study of collegiate cross-country runners found almost seven times increased risk for medial exercise-related leg pain in those with significant pronation. Two other studies of runners found little correlation between anthropometric measurements (femoral neck anteversion, pelvic obliquity, knee and patella alignment, rearfoot valgus, pes cavus/planus) and risk for injury. Only pelvic obliquity was a positive predictor of injury, and only in one study.

Dancers, like runners, are another population often studied for an association between biomechanical abnormalities and injury risk. Although dance medicine specialists often relate lower extremity injury to poor technique and misalignment, two independent studies failed to confirm such an association.

Studies of military recruits have provided much useful epidemiologic information because of the controlled nature of the population and their training regimen. A common injury among military trainees is the stress fracture. Although flatfeet have been a disqualifying factor for military service in the past, some studies have shown that recruits with flat or pronated feet had no greater incidence of stress fracture than the remaining population. A study of the relationship between arch height and stress fractures in Israeli military recruits showed an increased incidence of metatarsal stress fractures in recruits with a low arch but fewer tibial and femoral stress fractures. A study done on Navy SEAL trainees showed an increased risk of stress fractures of the lower extremity in recruits with either pes planus or pes cavus. It also showed that there was an increased risk of femoral stress fractures in trainees who had restricted hindfoot inversion and an increased risk of tarsal or metatarsal stress fractures in trainees with increased hindfoot inversion.

A study that attempted to correlate arch height with injury in runners found that transfer of foot eversion movement to internal leg rotation—a factor often related to knee pain—increased significantly with increasing arch height. However, arch height only contributed 27% to 34% of the variation in the transfer of movement between subjects. This indicates that other undelineated factors also influence kinematic coupling at the ankle–hindfoot joint complex, including the variation in plantar pressure pattern noted in runners with differing foot types. Theoretically, both the high-arched and the low-arched foot can cause impairment of subtalar and transverse tarsal joint function and thereby cause overuse injury.

The relationship between biomechanical differences in athletes and prevalence of injury is difficult to define. Alteration in biomechanics of an athlete, through training, orthoses, or other means can seemingly affect the injury rate of an athlete, this has not been defined in the literature. Perhaps, the true effect is not as great as some experts have suggested.

Flexibility

Pre-exercise or pre-participation stretching has long been thought to help prevent injury. A systematic review of the literature looking at neuromuscular warm-up strategies and injury prevention found a trend toward reduction in ankle sprains with practical neuromuscular warm-up strategies that included stretching and proprioception training, including the use of a balance board. Results improved when exercise was maintained for more than 3 months and performed on a regular basis in each training session. Lack of flexibility has often been cited as the factor responsible for various sports-related complaints, although prior in-depth reviews of the literature have failed to show a correlation between stretching and the rate of injury. Thacker et al and Krivickas and Feinberg prospectively studied two components of flexibility—muscle tightness and ligamentous laxity—in college athletes. They found a significant association between lower extremity injury and both tight ligaments and overall muscle tightness scores in men but not women. Owing to their small numbers for individual sports, the data could not be analyzed for specific sports. Because a discussion of flexibility and stretching can evolve into an expansive section of its own, the present discussion is confined to relevant comments specific to the foot and ankle.

Lack of flexibility about the ankle and foot or limitation in motion of certain joints can be seen in association with certain disease processes or conditions, but the more common situation in the sports setting is single joint involvement, as seen in tarsal coalition. Athletes may have reached highly competitive levels of participation before the coalition limits them to the extent that they seek medical attention. They typically have a history of frequent ankle sprains, and the limitation in subtalar motion in these patients with talocalcaneal coalition may have been overlooked in the past.

Restricted ankle motion in dorsiflexion is a factor in the anterior ankle pain seen in skiers and in runners who do hill work. This is often associated with anterior tibial and dorsal talar neck osteophytes at the ankle joint. Limited dorsiflexion of the ankle has been blamed for a multitude of other problems around the foot and ankle, including bunions, turf toe, midfoot strain and plantar fasciitis, ankle sprains, Achilles tendinitis, calf strains, and excessive pronation (including all the problems that it can allegedly produce). All these conditions have been related to a tight Achilles tendon and its effect in limiting ankle dorsiflexion, but no studies have unequivocally documented this relationship.

Limited motion in the toes rarely receives much attention as an etiologic factor in injury or symptoms. However, a lack of flexibility is one of the critical components in the diagnosis of certain conditions such as hallux rigidus, which involves a characteristic loss of dorsiflexion in the first metatarsophalangeal (MTP) joint ( Fig. 36-4 ). In dancers with acquired hallux rigidus, restriction in great toe dorsiflexion to less than 90 to 100 degrees can produce compensatory positions that predispose the dancer to ankle inversion sprains and misalignment syndromes. Limitation of motion in the other MTP joints is seen in patients with Freiberg's infraction. When the interphalangeal (IP) joints of the toes are involved in loss of motion, a problem seldom exists unless an associated deformity is present, such as a hammer toe or mallet toe. These conditions in athletes can produce sufficient symptoms to require surgical treatment.

At the opposite end of the mobility spectrum, hypermobility is infrequently mentioned as the source of problems in the foot and ankle in athletes. Pathologic laxity is common to certain connective tissue disorders, including Ehlers-Danlos syndrome, Marfan syndrome, Larsen syndrome, Down syndrome, hyperlysinemia, homocystinuria, and osteogenesis imperfecta. A hypermobility syndrome unassociated with known connective tissue disease has also been described as a potential source of musculoskeletal symptoms and signs, including ankle joint effusions.

In certain sports such as ballet and gymnastics, there is selectivity bias for the more flexible performer. Ballet dancers are particularly noted for the tremendous mobility in their feet and ankles. The same could be said for divers and gymnasts, who are awarded for having greater ability in achieving maximum plantar flexion so the foot assumes a pleasing line with the leg. Although this increased flexibility has obvious advantages, it may also have a negative side. Klemp et al have found an increased incidence of injury in ballet dancers who have greater mobility; others have failed to find such a relationship, however. While attempting to achieve the desired flexibility in ankle plantar flexion, the ballet student may develop posterior ankle pain from impingement with a large posterior talar process, calcaneal osteophyte, or os trigonum.

A pathologic increase in joint laxity is termed instability . Many studies have shown that a history of previous ankle injuries predisposes athletes to future ankle sprains. Chronic instability of the ankle joint, a dynamic interrelationship between mechanical and functional factors, is a major factor in recurrent injuries to the ankle, whether it is due to a proprioceptive deficit, loss of ligamentous integrity, or some other condition. A study by Willems et al has shown that patients with chronic ankle instability (CAI) have decreased proprioception at the extremes of inversion as well as decreased evertor strength when compared to normal counterparts. On the other hand, physiologic laxity has shown no similar trend. Clinically the difficulty is in differentiating between these two conditions. This is clarified further in the ankle ligament section.

Strength

It is a commonly held belief that weak musculature predisposes a person to injury in sports. It is often stated that weak peroneal muscles are a factor in inversion sprains of the ankle, and one of the goals of rehabilitation after an ankle sprain is to strengthen these muscles. Fully activated strong ankle evertors exceed three-quarter-top shoes, taping, and orthoses in the protection they offer to the inverted ankle at foot strike. Several studies have shown that improving strength can reduce the risk for reinjury. Most work in this area is related to strength in the thigh musculature about the knee. Similarly, muscle strength imbalances, which are viewed as creating a propensity for injury, have primarily been studied with reference to the quadriceps-to-hamstring ratio (ideally around 5 : 4 depending on the test method and test speed). Other studies have concluded that strength differences of more than 10% between the right and left legs increase the injury risk. Ekstrand et al used this figure in their prospective study on the prevention of soccer injuries. They discovered a 75% reduction in injuries with a prophylactic program that included rehabilitation, to the point that 90% of muscle strength had been regained.

No similar ratios are found for the ankle and its proximal musculature to guide rehabilitation or expose a greater potential for injury to the leg, ankle, or foot. Silver et al performed the baseline work on strength of the leg muscles. They reported the ratio of plantar flexors to dorsiflexors as 6 : 1, or stated conversely, the dorsiflexors are normally only 17% of the plantar flexors in terms of strength. The peroneals have only 8.1% mean strength in comparison to the dorsiflexors at 9.4% and the plantar flexors at 54.5%. The peroneus brevis muscle has a mean strength of 2.6% and the peroneus longus a mean strength 5.5% in comparison to the strongest muscle, the soleus, at 29.9%.

Strength imbalance in the leg is a clear risk factor for injury to the ankle. Baumhauer et al showed that athletes with a lower dorsiflexion-to-plantar flexion ratio had greater risk of injury. With a higher eversion-to-inversion ratio, the athletes had a higher incidence of inversion ankle sprains. This work was corroborated in a second isokinetic strength test study that showed invertor muscle strength deficiency was more important than evertor deficits in lateral ankle ligamentous injuries. A cohort study of professional soccer players in Greece showed an increased propensity for ankle sprains when athletes had preexisting functional strength asymmetries about the ankle. Another prospective study failed to find a relationship between ankle strength and muscle reaction time with the risk of ankle injury. Nevertheless, rehabilitation designed to restore the normal strength ratio through an isotonic and isokinetic strengthening program should reduce the risk of ankle injury.

The relationship between weakness and potential for injury in sports has been further corroborated by studies of soccer players. Backous et al performed a prospective study of boys attending a summer soccer camp, with the ankle being the most frequent site of injury. The highest incidence occurred in boys who were tall and had weak grip strength, which led the authors to conclude that skeletally mature but muscularly weak boys were at increased risk for injury compared with their peers.

Ekstrand and Gillquist found that soccer players who sustained a minor injury during the preceding 2-month period had a 20% increase in their risk of developing a more serious subsequent injury. Similarly, Bahr and Bahr noted a 42% increase in risk of reinjury in volleyball players who had suffered an ankle sprain within the preceding 6 months. This reinjury risk is attributed to inadequate rehabilitation and poor muscle strength and is supported by several studies.

With the weight of evidence supporting this association, this is the basis for working on strength as part of the rehabilitation process after injury or surgery ( Fig. 36-5 ). Furthermore, it is the precept on which college and professional athletic teams base their conditioning programs, including weight training.

Footwear and Orthoses

In the field of sports medicine, shoes have been blamed for athletic injuries caused by foot fixation on a playing surface resulting in increased rotational forces. With poorly fitting shoes, changes in design to become light and more flexible, athletic shoewear could be playing an increased role in athletic injuries. Traditionally the shoe was largely considered just a part of the uniform; however, this focus has changed and the relationship between the athlete contacting the ground, the shoe, and injury has become more studied. While shoewear is the most often cited etiologic factor for noncontact injuries to the knee and ankle, the relationship between the shoewear and the playing surface has become closer linked. Although this section deals with these two factors separately, the reader should keep in mind the relationship between them.

Rotational forces generated by the body at the shoe/surface interface are an important factor in sports injuries, but other factors are just as important. One of the most neglected but commonplace causes is improper fit of the athletic shoe. Just as this has been shown to be a prime cause of foot complaints in the general population, it is likewise a common source of relatively minor, although annoying, problems for athletes.

When the athletic shoe is improperly fitted, the overly tight shoe causes pressure-related pain at the site of bunions and bunionettes, or it can cause metatarsalgia. When the athletic shoe is too loose, it allows the foot to slide, and blisters result. When the shoe is too short, the toes jam into the end. This can result in nail problems or the black toes of long-distance runners. A more novel fitting-related problem occurs with tightly fitting ski boots, where excessive pressure at the ankle causes a neurapraxia of the posterior tibial nerve or the superficial peroneal nerve. Similarly, posterior tibial tendinitis or aggravation of an accessory navicular can occur from an ice-skating boot. Irritation of the Achilles tendon and production of a retrocalcaneal bursitis can occur from a variety of footwear, especially when there is a rigid heel counter. Careful fitting of the athlete can generally avoid or alleviate these types of problems rather than having to resort to surgical intervention ( Fig. 36-6 ).

The shoe can be a source of problems in other ways as well, such as a lack of cushioning or lack of support. Load on the human body has been implicated as a specific etiologic factor in sports injuries. Because a significant component of this load is the vertical impact force or ground reaction force, cushioning , or shock absorption, by the shoe is an important property. The ability of shoes to prevent injury through improved cushioning properties has had mixed reviews in the studies of this subject. Greaney et al showed a reduction in calcaneal stress fractures in military recruits by switching to tennis shoes. A study of South African military recruits reported a reduction in overuse injuries by incorporating a neoprene insole into the shoes used in training. A report on aerobic dance injuries included a mention of the beneficial effects of cushioned shoes in reducing injuries. However, a study of the U.S. Army Marching Band, whose members were switched to more cushioned shoes, showed no significant decrease in injuries. Other studies have also shown no benefit from increased shock absorption in either shoes or insoles.

An interesting counterproposal to the idea that improved cushioning in the shoe is protective to the body is the Robbins and Hanna hypothesis. They have proposed that increased cushioning can actually be an etiologic factor in injury by dampening the body's own sensory feedback mechanism coming from the plantar surface of the foot, thereby producing a “pseudo-neuropathic” condition. This is a thought-provoking concept, and barefoot exercise or performance does appear to have some benefits. It has even spawned a new trend in running shoes—the “minimalist” running shoe ( Fig. 36-7 ). Such shoes with little padding and arch support (with or without individual toe compartments) have become part of mainstream running. The traditional modern running shoe with increased cushioning and support allows more forceful heel strike and longer stride length while the minimalist shoe forces a shorter stride and better dispersion of forces across the entire foot. Improved dispersion of impact forces has been verified by biomechanical studies. Future research will be needed to compare injury rates between cushioned and minimalist shoes.

Traction between the shoe and the surface can be separated into two categories: rotational (or torque) and linear (or shear). As traction increases, the forces on the knee and ankle increase as well, resulting in greater propensity for injury in these areas. One study proposed that two thirds of all noncontact soccer injuries were related to excessive shoe surface traction. Load on the body related to traction has been studied with reference to both rotational and linear forces. Several components contribute to traction in footwear design analysis. These include the outsole material, sole pattern, and the presence of cleats as well as their number, length, and pattern. Torg et al studied football shoes and demonstrated precariously high torque when the shoes had ¾-inch-long cleats. Other shoe surface combinations were also considered potentially unsafe. Softer outsole materials are also associated with increasing torque when used on artificial or clean hardwood court surfaces, but the presence of dust on the floor can alter this effect.

Research has clearly documented the relationship between cleating of the athletic shoe and sports injuries. In one study of high school football injuries, the number of ankle injuries was halved by changing from the traditional seven-cleated grass shoe to a soccer-style shoe. Further support for this came from Torg and Quedenfeld, who found a reduction in ankle injuries from 0.45 per team per game while using conventional cleats to 0.23 injuries in soccer-style shoes. Similar reductions have been reported in other studies evaluating other cleating patterns and surfaces. From the opposite standpoint, a lack of traction can potentially cause injury by increasing the frequency of slips and falls. Biener and Caluori reported that slipping on wet tennis surfaces was a factor in 21% of injuries.

Clearly, problems can occur from either too much or too little traction. Athletes and coaches demand maximum traction for superior performance, but there comes a point where this can exceed the body's ability to handle the load. A study of two shoes with treaded versus smooth sole design found increased traction with the treaded design, resulting in increased forces on the knee and ankle. Despite this, there was no difference in performance noted between the two shoes.

An ongoing debate in the shoe equation as it relates to injury is high-top versus low-top shoes. Relatively few studies have scientifically investigated the value of different shoe heights in reducing ankle sprains. High-top shoes can be at least 50% stiffer than low-cut models and are affected by both the material and the geometry of the shoe. This stiffness reduces the load carried by the collateral ligaments of the ankle. Conversely, when mobility necessitates use of a low-cut athletic shoe, the same mathematical model predicts the need for a low-stiffness shoe to allow maximum subtalar motion. Theoretically, the high-top shoe should stimulate the proprioceptive feedback mechanism, resulting in greater sensitivity of the peroneal muscles and improved stability for the ankle. Garrick and Requa found a reduced frequency of recurrent ankle sprains in college intramural basketball players who used prophylactic taping and high-top shoes. In another clinical study, Milgrom et al found no evidence that high-top boots lowered the incidence of ankle injuries among Israeli military recruits when compared with three-quarter-top basketball shoes. A prospective randomized study of high-top versus low-top shoes reached a similar conclusion related to the prevention of ankle sprains. Ottaviani et al have shown that basketball shoe height increases the maximum resistance to an inversion moment but does not affect the athlete's ability to resist an eversion moment. According to one study, active ankle evertor muscles provide greater protection to inversion stress than three-quarter-top shoes, athletic taping, or orthoses.

In recent years there has been extensive research into the biomechanics of ankle taping and bracing, which have shown differences in a variety of different biomechanical and neuromuscular measurements, including restriction of maximum ankle motion and improvements in peroneal muscle response during inversion movements. Ankle taping does improve proprioception, which is generally accepted to reduce the risk of injury to the ankle. Nevertheless, there continues to be debate over the best method for preventing ankle sprains related to taping, bracing, and high-top shoewear.

Playing Surfaces

Load on the athlete as a factor in injury has led to a critical analysis of playing surfaces since 1980. This has primarily been stimulated by the introduction of artificial playing surfaces and particularly by the allegations that artificial grass causes increasing injury rates. Although substantial attention has been given to this subject in both the lay and the medical communities, there is still substantial debate over the degree and manner by which playing surface differences (particularly artificial turf vs. natural turf) increase risk of injury in sports. It does appear that third- and fourth-generation artificial turf have only minimal differences in injury rates compared to natural turf except perhaps for ankle injuries occurring more frequently on artificial turf. It has been demonstrated recently that athletic play on synthetic turf does result in a 16% increase in injury related to natural grass. Synthetic turf changes have led to different maintenance practices. The safety and quality of the field, including the maintenance standards, can affect the injury rates of the participating athletes.

Although artificial surfaces have received the most attention, evidence also indicates that natural grass is a factor in injuries as well. This is particularly true when the field is not maintained properly. The classic 1974 study of high school injuries by Mueller and Blyth reported a 30% reduction in the injury rate by resurfacing and maintaining the grass practice and game fields. Several studies of soccer, dance, and even ice hockey injuries have also indicated the playing surface as a factor. One of the most important studies on the relationship between injuries and playing surfaces is that of Janda et al, who found 70% of recreational softball injuries to be related to sliding into fixed bases. The follow-up to this study showed a 98% reduction in serious injuries with the use of breakaway bases.

In running, hard surfaces and hills are seen as important factors in injuries, but few confirmatory studies have been done. The Ontario cohort study, one of the better epidemiologic studies of running injuries, found no relationship between surface and injury. A simultaneously reported 1989 study from South Carolina noted the only significant relationship between injuries and training surface to be in female runners running on concrete. Powell et al examined the multiple etiologic factors involved in running injuries, including the running surface, and found little correlation. These studies have primarily examined injury from the standpoint of surface hardness. An alternate viewpoint is found in the European literature, where “eigen-frequencies,” or vibrational forces, from synthetic tracks are seen as a major factor in overuse problems in track athletes. Haberl and Prokop have described this as “tartan syndrome,” a surface-related problem from “long-term non-physiologic stress, resulting in acute, chronic or periodical irritant states.” There is no conclusive evidence to confirm the exact importance of vibrational forces in running injuries.

In the analysis of athletic injuries to the lower extremities, the diligent clinician will develop knowledge of the injuries common to certain sports and the factors that play a role in their occurrence. Intrinsic and extrinsic factors must all be taken into consideration and form a matrix from which to assess the injured athlete, design a plan of treatment and rehabilitation, and ultimately to intervene where possible to alleviate the factors most likely to predispose the athlete to injury.

Differential Diagnosis

Many conditions must be considered when evaluating chronic leg pain in athletes, including but not limited to exertional compartment syndrome, medial tibial stress syndrome (MTSS), stress fractures, gastrocnemius and other muscle strains, nerve entrapment syndromes, venous disease, arterial occlusion, fascial herniations, tendinitis, and radiculopathies ( Table 36-2 ). Using appropriate history and physical examination cues in conjunction with appropriate secondary diagnostics tests, the appropriate diagnosis can be narrowed down from the multitude of potential diagnoses that can be the underlying cause of chronic leg pain. Using knowledge of anatomy and physiology, as in most circumstances in orthopaedics, the clinician can better understand the particular causes for a particular athlete suffering from chronic leg pain and develop a treatment and rehabilitation plan that leads to a safe and pain-free return to sport.

Incidence

Although it is difficult to assess the relative incidence of the various conditions that produce leg pain in the athletic population, it seems that about 25% relate to exertional compartment syndromes, 25% to stress fractures, and 25% to MTSS or periostitis. This leaves a final 25% composed of an assortment of the less common causes, from radiculopathies to venous problems. Reviewing the literature on this subject leads to the conclusion that an accurate diagnosis is not always a certainty and coexisting pathologic entities may be more the rule than the exception. Up to 60% of patients with exertional leg pain have associated periostitis. This periostitis corresponds most closely to the commonly used lay description for nonspecific exertional leg pain: shin splints . This has been used for the diagnosis in up to 15% of all running injuries in some studies. Clearly, exertional leg pain is the source of many symptoms in the athletic population, and there is still ample opportunity for improving the accuracy of the diagnosis.

Chronic Exertional Compartment Syndrome

Etiology

Chronic exertional compartment syndrome (CECS) is an elevated compartment pressure in one or more of the fascial compartments of the lower leg caused by exercise that produces leg pain. In theory this pain has been attributed to local ischemia in the muscles and nerves due to impaired tissue perfusion. The firm boundaries of the fascial compartments in the leg ( Fig. 36-8 ), when coupled with increased muscle bulk secondary to muscle contraction, intracellular and extracellular fluid accumulation, and muscle microtears, are responsible for the increasing pressures ( Fig. 36-9 ). Arterial inflow remains normal, and venous and lymphatic compromise contribute to the cycle of increasing tissue pressure, resulting in vascular compromise at the capillary level. This theory has been challenged by others who have not found signs of ischemia and propose that the pain is due to increased oxygen demand versus supply, fascial stretch, and/or stimulation of sensory nerves that respond to pressure or stretch. The absence of ischemia was confirmed in a well-designed MRI study by Andreisek et al, who found no difference in T2 relaxation times or arterial spin labeling signal between patients diagnosed with CECS and control subjects.

Diagnosis

Clinical evaluation

Physical examination performed with the patient at rest is typically unremarkable. Usually, some tenderness is noted over the affected compartment and over the middle to lower third of the tibia (from associated periostitis). Examination immediately after a period of exercise is often required to provoke the symptoms and expose the signs to the examiner. In this situation, tenderness over the affected muscle compartment and palpable firmness are more common. Muscle herniations through fascial defects are often discovered, but there is significant divergence of opinion on both their significance and incidence.

The neurologic examination is usually uneventful, but signs of deep peroneal nerve compression (up to and including a foot drop) can occur when the anterior compartment is affected. Concurrent superficial peroneal nerve entrapment is common with lateral compartment syndrome and produces numbness or tingling into the dorsal foot. Arterial pulses should be checked and documented but are normal in CECS.

Radiologic evaluation

Radiologic evaluation is warranted in all cases because stress fractures can mimic these symptoms and an occult tumor can be found even in an unlikely setting ( Fig. 36-10 ). Lack of specific localized uptake on the technetium bone scan or no increase in signal on T2-weighted MRI images of the painful area effectively rules out a stress fracture. MRI has gained increasing acceptance in the evaluation of chronic leg pain and compartment syndromes, with some advocating its use as a reliable, reproducible, and noninvasive diagnostic tool with no radiation exposure.

Pressure measurements

In general, the diagnosis of CECS can be made on clinical grounds. The syndrome can be confirmed with compartment pressure measurement. Although one would expect to have a certain agreed-on method and a specific pressure measurement for diagnosing compartment syndrome, this has not been the case. The suggested methods and the timing of the measurement have varied considerably. Box 36-1 lists the criteria we use. The test for exertional compartment syndrome can be performed quickly with a digital pressure monitor, but the physician should always be certain that the numbers are consistent with the clinical picture before deciding the treatment option. Interestingly, Winkes et al demonstrated the inaccuracy of catheter placement in measuring specific compartments. Thus, ensuring the placement of the catheter can provide more reliable and accurate readings.

Box 36-1

Criteria for Diagnosis of Chronic Exertional Compartment Syndrome

Data from Pedowitz RA, Hargens AR, Mubarak SJ, et al: Modified criteria for the objective diagnosis of chronic compartment syndrome of the leg, Am J Sports Med 18:35–40, 1990.

Mandatory

• Appropriate clinical findings

Secondary (At Least One)

• Compartment pressure ≥15 mm Hg before exercise

• Compartment pressure ≥30 mm Hg at 1 min after exercise

• Compartment pressure ≥20 mm Hg at 5–10 min after exercise

Medial Tibial Stress Syndrome

Diagnostic Imaging

Radiographs are taken to exclude other sources of tibial pain. Bone scan findings usually demonstrate diffuse linear uptake along the posteromedial border of the tibia that involves as much as one third of the bone's length ( Fig. 36-14 ). An MRI may provide a clearer picture of periostitis at the fascial insertion of the soleus.

Authorities debate the value of compartment pressure measurements in this syndrome. Some suggest that the MTSS is actually caused by a superficial posterior, deep posterior, or isolated posterior tibial compartment syndrome and have reported higher pressures in the affected compartments. At the other extreme, studies have demonstrated completely normal pressures before, during, and after exercise. Despite this dichotomy, the possible coexistence of anterior compartment syndrome with the MTSS, reported by Allen and Barnes to be 50%, makes measurement of compartment pressures a valuable adjunct in these patients.

Diagnosis is based on the characteristic history and physical examination coupled with negative radiographic findings and a positive bone scan or MRI. Relief of pain after the injection of a local anesthetic agent can also help in establishing the diagnosis.

Stress Fractures of the Tibia and Fibula

Stress fractures of the foot and ankle are covered in more detail in Chapter 38 , but their occurrence in the legs of athletes is of particular interest when chronic leg pain is the issue. Stress fractures result from abnormal repetitive loads on the bone that cause an imbalance of bone injury versus repair.

Running is the most common sport producing tibial and fibular stress fractures. A prospective study of 53 female and 58 male track athletes reported a 21.1% incidence of stress fractures during a 1-year period, and 58% of these were to the tibia or fibula. Other sports with frequently reported tibial and fibular stress fractures are basketball, soccer, skating, aerobics, and ballet. Dancers and basketball players are particularly vulnerable to the dreaded anterior midtibial stress fractures.

One study of risk factors for stress fractures in athletes with three or more separate stress fractures suggests that leg length discrepancy, a high longitudinal arch (pes cavus deformity), and excessive forefoot varus can predispose to stress fractures. Athletes with diminished mineral content (e.g., amenorrheic female athletes) may be especially vulnerable. Additionally, vitamin D deficiency has become an increasingly recognized problem related to stress fractures in athletes.

Diagnosis

In most cases of stress fracture, radiographs are normal at the onset of symptoms, but by 2 to 3 weeks there is a small cortical lucency or, more typically, a mild localized radiodense haze. With time, a more defined periosteal reaction with cortical thickening may be appreciated. Occasionally a transverse cortical lucency occurs and indicates a more foreboding type of stress fracture. Normal x-ray findings, even after several months of symptoms, do not rule out a stress fracture. In this situation, a technetium bone scan is a more sensitive study. In the presence of a stress fracture the scan will show intense localized uptake ( Fig. 36-15 ). Other study options include high-resolution computed tomography (CT) scanning and MRI.

Surgical Treatment

The special nature of the anterior tibial transverse stress fracture deserves further discussion because it represents a challenging management problem. Once this fracture shows evidence for radiolucency, the risk of nonunion or complete fracture increases ( Fig. 36-16 ).

Various recommendations for surgical treatment have been made. Some authors recommend excision and bone grafting if no healing occurs with conservative treatment, whereas others propose treatment with pulsing electromagnetic fields (PEMFs) for 10 to 12 hours daily for 3 to 6 months, with or without associated immobilization, before considering surgery for bone grafting. Surgical options typically include tension band plating or intramedullary (IM) nailing. The surgical option most commonly performed on athletes and military personnel with recalcitrant tibial stress fractures is IM nailing of the tibia with a reamed nail ( Fig. 36-17 ). Chang and Harris reported five of five military patients all had good to excellent results with an IM nail, and another series of seven dancers treated surgically with either bone grafting or IM nailing resulted in return to full dance activity at an average of 6.5 months postoperatively in t often avulses rather than tearing in midsubstance all seven patients. Zbeda et al showed that tension band plating is a viable alternative with 92% of the athletes returning to sport. A systematic review by Chaudry et al demonstrated that nearly 95% of high performance athletes treated with surgery for anterior tibial stress fractures, no matter which technique, are able to return to sports.

Gastrocnemius-Soleus Strain

A strain or rupture of the gastrocnemius-soleus muscle complex is a common injury in sports and is seen commonly in racquet sports, basketball, running, and skiing. Some confusion once existed over whether this entity represented a rupture of the plantaris muscle or tendon. Because this rupture was demonstrated in only one or two of the surgical cases in the literature, it is safe to assume that the majority of cases represent injury to the gastrocnemius or soleus muscles.

Nerve Entrapment Syndromes

Various nerve entrapment syndromes that are responsible for exercise-induced leg pain have been described. These are covered in some detail in other chapters and discussed only briefly here. The most common entrapment syndrome in the athlete is entrapment of the superficial peroneal nerve ( Fig. 36-18 ). The other entrapment syndromes include a high tarsal tunnel with entrapment of the posterior tibial nerve, entrapment of the common peroneal nerve at the neck of the fibula, saphenous nerve entrapment as it pierces Hunter canal, and sural nerve entrapment in the posterior portion of the calf.

Popliteal Artery Entrapment Syndrome

Popliteal artery entrapment syndrome (PAES) is a relatively rare entity that causes calf pain in young athletes. The sports medicine specialist or orthopaedic surgeon may encounter it initially. If the physician is unaware of this problem as a potential source of leg pain, the condition may be undiagnosed or misdiagnosed, with the devastating result of below-knee amputation. Because the condition closely mimics the leg pain seen in chronic exercise-induced compartment syndrome, the physician should be particularly cautious in the patient in whom compartment syndrome is the suspected diagnosis. When PAES is suspected on the basis of the clinical evaluation, further diagnostic procedures can confirm the diagnosis and lead to appropriate treatment.

Diagnosis

Clinical evaluation

Patients with PAES are usually young and athletic and present with cramping pain in the calf during exercise. This can be typical intermittent claudication, or it can be quite atypical. The condition can be seen bilaterally in up to 67% of patients. A sensation of tingling in the toes may be described, but objective neurologic findings are rare. Physical findings are surprisingly limited in the early stages of this condition, and provocative testing may be required. Pulses may be diminished or absent, particularly after exercise or with the knee in hyperextension and the foot plantar flexed against resistance. The knee is sometimes warm to the touch from increased collateral circulation, and the foot may be cool. Signs of ischemia are usually caused by thrombosis of the artery subsequent to damage of the intimal lining or aneurysm formation. A palpable popliteal mass with pulsation or a bruit suggests an aneurysm. Distal embolization can produce ischemic gangrene.

Functional PAES can occur in well-conditioned athletes. Forced plantar flexion causes compression of the neurovascular bundle and produces symptoms of claudication because of the overdeveloped medial gastrocnemius, soleus, and plantaris musculature.

Diagnostic studies

In the patient with exertional leg pain, further studies are often indicated to make a definitive diagnosis. Provocative testing with treadmill walking or running is often helpful. This is the usual sequence of evaluation in chronic compartment syndrome as well, so the physician should keep the possibility of PAES in mind and examine the patient after exercise for absent pulses. Compartment pressure measurements can reveal a reduction in compartment tissue pressure in PAES. Doppler pressure measurement usually shows a reduction in pulse pressure, and this can be seen visually with pulse volume tracings before and after exercise. Continuous-wave Doppler and duplex scanning studies at rest and with active contraction of the calf muscles can detect decreased flow in this condition. Ultrasonography can also be used to confirm the deviation in the course of the popliteal artery and demonstrate an aneurysm. Other useful noninvasive studies include computed tomographic angiogram (CTA), angiogram, and magnetic resonance angiography (MRA). A stress-related MRA study may be even more sensitive.

The definitive diagnostic study has been digital subtraction angiography (DSA) performed after exercise ( Fig. 36-19 ). The characteristic findings are medial deviation of the popliteal artery, segmental occlusion of the popliteal artery, poststenotic dilation of the popliteal artery, stenosis of the popliteal artery with hyperextension of the knee and passive dorsiflexion of the ankle, and active plantar flexion of the ankle. These findings usually indicate permanent changes to the artery.

Treatment

If the patient's symptoms are entirely exercise related and not severe, nonsurgical treatment with avoidance of symptom-producing activity should be considered, but the vast majority of these patients require surgical treatment. This is obvious when ischemic changes are present. When the patient has only symptoms of intermittent claudication with sports activity, the decision to intervene surgically is more difficult. Nevertheless, the potential risks in this condition are such that surgery should be performed in almost all circumstances. When PAES is diagnosed early and no damage to the artery occurs, release of the artery from the entrapping structure may be adequate. When changes occur in the artery, these must be addressed with the appropriate vascular procedure, including excision and reanastomosis, saphenous vein bypass grafting, or endarterectomy.

The best results occur when the condition is diagnosed early and can be treated by simple division of the musculotendinous structure that is compressing the popliteal artery. di Marzo et al have reported a 94.4% long-term patency rate at a 46-month average follow-up in this situation. When arterial grafting becomes necessary, the long-term patency rate decreases to 58.3%.

Venous Disease

Effort thrombosis is a recognized condition affecting the upper extremity and is called Paget-Schroetter syndrome . The condition is quite rare in the lower extremity but has been reported. Pain and swelling in the lower extremity associated with distended superficial veins and discoloration should alert the physician to the diagnosis, which is confirmed by venography. Treatment is immediate short-acting anticoagulation followed by chronic longer acting oral anticoagulation therapy.

Thrombophlebitis can accompany either acute or chronic injury to the leg and can be a factor in prolonging recovery. Several factors increase the likelihood of phlebitis related to the athletic setting: immobilization after injury, inactivity during prolonged bus or air transportation after an event, high altitude, dehydration, alcohol or drug abuse, estrogen-based oral contraceptives, and hemoglobinopathies (e.g., sickle cell trait). Furthermore, while dealing with athletes, the health care provider should keep in mind the possibility of a genetic predisposition to thrombophlebitis. The most common thrombophilia conditions are factor V Leiden and prothrombin G20210A. The best preventive measure in such patients is taking a good history for a family history of deep vein thrombosis and/or pulmonary embolism. Routine screening of orthopaedic patients is not recommended but may be warranted with a positive family history. Though rare, effort thrombosis and thrombophlebitis should be kept in mind as potential sources of leg pain symptoms in the athletic patient and should be investigated with blood tests, venography, or other noninvasive studies when suspicion is aroused.

Delayed-Onset Muscle Soreness

It is well known that exercise can produce muscle pain and even damage to the muscle, particularly in the person unaccustomed to strenuous activity. This is especially true for eccentric muscle contractions and is based on microinjury to the muscle, with the initial lesions occurring at the subcellular level. As a consequence of this injury, the muscle is temporarily unable to generate maximum force. Metabolic changes are evident, including elevation in blood levels of muscle-derived enzymes, myoglobin, and metabolites.

Delayed-onset muscle soreness (DOMS) can vary from very mild to quite severe. Symptoms include not only muscle soreness and pain but also fatigue, stiffness, and a certain loss of performance that develops 24 to 48 hours after exercise and subsides by 5 to 7 days. The most common source of this pain is downhill running, which involves an eccentric contraction of the muscles.

Treatment of DOMS is symptomatic, and the patient is cautioned to avoid repetition of overly strenuous muscle activity during the recovery period because it can delay recovery and cause more significant damage. Newer treatment modalities include (1) vibration therapy, which has been shown to reduce the inflammatory cytokine interleukin 6 (IL6); (2) caffeine ingestion following eccentric exercise, which reduces DOMS pain through its action as a nonselective adenosine receptor antagonist; and (3) pre-resistance cardioacceleration before resistance exercise sets in order to increase blood perfusion to the muscles.

Anatomy

The lateral ligamentous complex of the ankle consists of three ligaments: anterior talofibular, calcaneofibular, and posterior talofibular. The lateral ligamentous complex of the subtalar joint consists of five important structures: calcaneofibular ligament, inferior extensor retinaculum, lateral talocalcaneal ligament, cervical ligament, and interosseous talocalcaneal ligament ( Fig. 36-20 ). The calcaneofibular ligament spans both the tibiotalar and talocalcaneal joints and is crucial to the proper biomechanics of both joints. It is the most critical lateral stabilizing structure for subtalar stability.

The anterior talofibular ligament (ATFL) is a flat ligament that blends with the anterior lateral capsule of the ankle. It is composed of one to three bands, with a small cleft permitting the penetration of vascular branches from the perforating peroneal artery ( Fig. 36-21 ). The most common form is bifurcate (50%–59%) with a single ligament less common (23%–38%) and trifurcate least common (12%–18%). The ligament is 15 to 20 mm long and spans the anterior lateral ankle joint. It originates at the distal anterior fibula and inserts on the body of the talus just anterior to the articular facet. It does not insert on the talar neck. The ATFL makes an angle of approximately 25 degrees from the horizontal plane. The ligament is approximately 6 to 8 mm wide and 2 mm thick. Presence of additional bands does not significantly change these dimensions.

The posterior talofibular ligament (PTFL) originates from the medial surface of the lateral malleolus and courses medially in a horizontal manner to the lateral and posterior aspect of the talus ( Fig. 36-22 ). The PTFL is 3 cm long, 5 mm wide, and 5 to 8 mm thick. The insertion is broad and involves nearly the entire posterior lip of the talus. The ligament is confluent with the joint capsule and is well vascularized by vessels going to the talus and the fibula via the digital fossa.

The calcaneofibular ligament (CFL) is a cordlike ligament that originates from the anterior border of the distal lateral malleolus just below the origin of the ATFL. Contrary to popular belief, the CFL does not originate from the tip of the lateral malleolus. The ligament courses medially, posteriorly, and inferiorly from its fibular origin to the calcaneal insertion. The CFL is confluent with the peroneal tendon sheath, just as the ATFL blends with the anterior capsule of the ankle joint. The CFL is 2 to 3 cm long, 4 to 8 mm wide, and 3 to 5 mm thick. It typically runs 10 to 45 degrees posterior to the line of the longitudinal axis of the fibula. The angle between the CFL and ATFL is between 104 and 132 degrees—an important detail to remember during reconstructive procedures. The ligament inserts on a small tubercle posterior and superior to the peroneal tubercle of the calcaneus. Calcaneal insertion of the CFL is variable, so there is variation in the obliquity of the CFL to the long axis of the fibula.

Continuing with the hindfoot complex, the inferior extensor retinaculum (IER) is composed of three distinct components: lateral, intermediate, and medial roots (see Fig. 36-20D ). The lateral root originates superficial to the extensor tendons, and the intermediate and medial roots come from the deep fascial layer below the extensors. The lateral root inserts on the lateral aspect of the anterior superior process of the calcaneus. Together with the CFL and lateral talocalcaneal ligament (LTCL), the lateral root of the IER constitutes the superficial ligamentous support of the subtalar joint. The intermediate root runs from beneath the extensor tendons alongside and slightly posterior to the cervical ligament, while the medial root courses more deeply within the sinus tarsi and sends attachments to both the talus and the calcaneus adjacent to the talocalcaneal ligament in the sinus tarsi (tarsal canal).

The lateral talocalcaneal ligament (LTCL) originates from the body of the talus just inferior to the ATFL and inserts on the lateral wall of the calcaneus just anterior to the calcaneal origin of the CFL. Often this ligament can be seen as an arcuate complex blending with the CFL and ATFL. The extent of its development varies such that it is absent in 42% of cases, blends with the CFL in 35%, and is completely separate in 23%.

The cervical ligament (CL) lies within the sinus tarsi and forms a strong, distinct band of collagenous tissue that connects the neck of the talus with the superior surface of the calcaneus ( Fig. 36-23 ). The ligament runs in an oblique direction from the talus above to the calcaneus below and makes about a 45-degree angle with the horizontal plane. It is about 2 cm in length, 12 mm in width, and 3 mm thick.

Although not a lateral structure, the interosseous talocalcaneal ligament (ITCL) is important to the overall function of the hindfoot complex. The IOL measures approximately 15 mm in length, 5 to 6 mm in width, and 1 to 2 mm in thickness. It is located at the most medial aspect of the sinus tarsi and extends from a ridge at the sulcus tali. A large vascular foramen is posterior to the ligament's origin, and the middle facet joint between the talus and calcaneus is anterior to the IOL. The ligament then courses downward and lateral to the sulcus calcanei, where it blends with the most medial fibers of the CL. The IOL blends into the deep portion of the deltoid ligament on its medial side.

Pathology

From a literature review, laboratory studies, clinical experience, and surgical findings, the most common ligament disruption by far involves the ATFL. Most of these disruptions are midsubstance, but bony avulsions of the talus and fibula can occur. Indeed, Berg has suggested that the symptomatic os subfibulare is a nonunion of an avulsion fracture of the ATFL. The second most common injury is a combination rupture of the ATFL and CFL. Midsubstance rupture is most common, but a considerable number also involve avulsion of the CFL from the fibula or calcaneus. Isolated tears of the CFL are uncommon lesions but have been reported and may be important in late subtalar instability. Even less common are combination tears of the ATFL, CFL, and PTFL. Isolated injuries of the PTFL and isolated combinations of CFL and PTFL are exceedingly rare.

Persistent pain or complaint of instability to a previously injured ankle can be categorized into two types of instability: functional and mechanical. Functional instability is a common complaint of a patient having the feeling or sensation of the ankle being unstable with no change in structure. Functional instability benefits from proprioception training and strength training that help stabilize the ankle during ambulation. Mechanical instability is found on physical exam with increased range of motion about the ankle beyond physiologic ranges and is most commonly a result of ligamentous support disruption.

Injury to the ligaments can result in laxity of the ankle complex, but neuromuscular deficits are also likely secondary to nervous and musculotendinous tissue injury. Neuromuscular deficits can manifest as impaired balance, reduced joint position sense, slower firing of the peroneal muscles to inversion stress of the ankle, slowed nerve conduction velocity, impaired cutaneous sensation, strength deficits, and decreased dorsiflexion range of motion. Abnormal formation of scar tissue after injury can lead to sinus tarsi syndrome or anterolateral impingement syndrome, which can lead to functional instability of the ankle complex.

Various injuries are noted in association with lateral ligamentous sprains: partial or complete tears of the peroneus longus and brevis tendons, chondral fractures of the talus, osteochondral fracture in the talocrural joint, medial ligamentous injuries, syndesmotic injuries, and bifurcate ligament injuries. Displaced or nondisplaced avulsion fractures of the fifth metatarsal and calcaneocuboid compression injuries or ligament avulsions have also been noted. Fracture of the lateral process of the talus, known as snowboarder's fracture , manifests with signs and symptoms of a lateral ankle injury that can mimic a severe lateral ankle sprain ( Fig. 36-24 ). These less common injuries must be kept in mind when evaluating patients and their radiographs. Although complete nerve disruption has not been reported, it is common to see a post-sprain neuritis of the sural nerve, superficial peroneal nerve, deep peroneal nerve, or posterior tibial nerve.

Diagnosis

Clinical Evaluation

Patients with a lateral ankle sprain often describe a popping or tearing sensation in the ankle and occasionally an audible noise. Often they remember only the pain and loss of support. The injuries occur during running or cutting or while landing from a jump (often by landing on another athlete's foot). Patients who can remember the specifics describe an inversion, plantar flexion, or internal rotation mechanism. Swelling and pain occur immediately after the injury. Typically, patients with a complete ligamentous tear and those with tears of two or more ligaments have difficulty in weight bearing, although this is not always the case. Many athletes give a history of multiple ankle sprains.

Physical examination reveals swelling and tenderness over the affected ligaments. An understanding of the anatomy of each ligament allows a systematic sequence of palpation. Meticulous examination with fingertip palpation of all structures potentially involved in an ankle sprain often leads the examiner to the correct clinical diagnosis. However, the physician should keep in mind that as the time between injury and examination increases, the specificity of tenderness significantly decreases.

Despite a meticulous physical examination, an MRI study by Frey et al suggested that physical examination was found to be 100% accurate in the diagnosis of grade III injuries but only 25% accurate in the diagnosis of grade II injuries. Other associated injuries (e.g., significant capsular ruptures, tendon damage) were often overlooked at physical examination.

The range of motion of the ankle is limited in dorsiflexion, plantar flexion, and inversion. An anterior drawer maneuver often elicits pain in patients with an ATFL injury, although patients with complete rupture might have less pain than those with a sprain or partial rupture. In a relaxed patient with a complete ATFL tear, anterior subluxation of the talus may be appreciated, and a suction sign is usually apparent at the anterolateral joint ( Fig. 36-25 ). The test can be performed in one of two ways. With the patient seated on a bench and the leg hanging off the end with the knee bent, the examiner stabilizes the tibia with one hand while pulling the foot forward with the other hand behind the heel. Alternatively, with the patient lying supine or sitting with the knee bent 60 to 90 degrees and the heel stabilized against the ground or a flat surface, the examiner directs posterior pressure against the distal tibia ( Fig. 36-26 ).

An inversion stress of the calcaneus induces pain or demonstrates instability in patients with calcaneofibular disruption. It is very difficult to differentiate tibiotalar from talocalcaneal opening with this maneuver in the acutely injured patient. In fact, it usually is not possible to perform this maneuver in the acutely injured patient without some type of anesthesia. It is important to evaluate the syndesmosis in all ankle sprains because a surprising number of injuries occur to this area but go unrecognized. (See the section on syndesmosis injuries.)

With a thorough examination the physician can also find involvement of the peroneal or posterior tibial tendons. Avulsion or hairline fractures of the fibula, tibia, calcaneus, fifth metatarsal, cuboid, or talus and subtle neurologic injuries can also be detected. Predisposing factors such as varus hindfoot alignment, hypermobile joints, and tarsal coalition should be considered. It is also important to check closely for subtle breaks in the skin in cases of severe sprains since this may indicate an open dislocation with spontaneous reduction.

Radiologic Evaluation

Once a concise clinical impression has been reached, radiographic evaluation can confirm the presence of bony lesions as directed by the physical examination. In most situations it is advisable to obtain three views of the ankle: anteroposterior (AP), lateral, and mortise views. Routine x-ray films must be analyzed critically for avulsion fractures, osteochondral injuries involving the joint surface, and occult fractures. In the proper setting, stress radiographs are valuable, although this is seldom applicable to the acute ankle sprain.

The Ottawa Ankle Rules are the commonly used criteria for predicting which patients require radiographic images. Radiographs are only required for those patients with pain in the malleolar zone plus any one of the following: bone tenderness at the distal 6 cm of the posterior edge of the tibia or the tip of the medial malleolus, bone tenderness at the distal 6 cm of the posterior edge of the fibula or lateral malleolus, or inability to bear weight (four steps) either immediately after the injury or in the emergency department. According to Stiell et al, following these rules should provide nearly 100% sensitivity for detecting fractures while significantly reducing the number of unnecessary radiographs. A systematic review by Jonckheer et al that included one systematic review and 21 primary studies found sensitivity and specificity of the Ottawa Ankle Rules to range from 92% to 100% and 16% to 51%, respectively. Although these criteria are useful, patients who present to an orthopaedic surgeon may have already been evaluated in the emergency department or by a general practitioner and most likely require radiographs, since these criteria will commonly miss certain injuries such as the lateral process of the talus, anterior process of the calcaneus, osteochondral fractures of the talus, and avulsion fractures of the lateral ligaments.

Talar tilt

The talar tilt view is an AP view of the ankle while an inversion force is applied. Methods of obtaining this test vary greatly in the literature. Some authorities perform the test manually, and others use a jig with specifically defined stresses. Laurin et al have demonstrated similar results with both methods. Although local anesthesia, no anesthesia, or general anesthesia may be used for this test, good data support the need for anesthesia to obtain more reliable results from stress diagnostic tests in the acutely sprained ankle. Different authors recommend dorsiflexion, neutral position, or plantar flexion (or some combination) of the foot during the stress maneuver. Finally, position of the knee, with either a straight knee or a flexed knee, has also been disputed. We typically perform the test with the foot in relaxed plantar flexion, the knee slightly bent, and without the use of a foot-holding apparatus.

Great variability exists in what is considered to be a normal or abnormal talar tilt angle. Rubin and Witten's oft-quoted study analyzed 152 normal ankles with the talar tilt view and found a range extending up to 23 degrees. However, only two ankles were greater than 20 degrees and only six more than 15 degrees. Multiple studies have addressed this subject. Some have found great variance in “normal” talar tilt values, whereas others have shown a narrower range for the normal talar tilt. The talar tilt is less than 15 degrees in 95% of ankles. Side-to-side comparison is equally controversial because many studies suggest a lack of consistency when comparing a patient's two normal uninjured ankles. We have used 15 degrees as our cutoff for the talar tilt angle and consider this to indicate a high probability of a complete tear of the ATFL (and most often the CFL as well). A positive talar tilt in neutral or slight dorsiflexion is more indicative of a complete tear of the CFL ( Fig. 36-27 ). We do not routinely obtain comparison x-ray films of the uninjured ankle.

Anterior drawer test

The anterior drawer test primarily evaluates the ATFL with the foot in relaxed plantar flexion. This test involves a lateral radiograph performed while the ankle is undergoing an anterior displacement stress. The stress may be applied manually or by a jig. Various studies have calculated the normal value for anterior subluxation to range from 2 to 9 mm, with the majority being under 4 mm for the maximum ( Fig. 36-28 ). When the anterior translation is greater than 5 mm, we consider the ATFL ruptured.

Other techniques

Although most authors believe that stress radiographs have largely replaced arthrograms, several studies of arthrograms after ankle injuries have found the diagnostic accuracy of arthrography is higher than the clinical examination and stress radiographs. Perhaps the best indication for this test is in an athlete suspected of having a severe complete sprain of the lateral ankle complex when an MRI is unavailable. If the test is performed within the first 24 hours, the diagnostic accuracy appears to be quite high. Some believe that the test can still be valuable up to 4 or 5 days after injury.

Peroneal tenography may also be done to help diagnose tears of the CFL. It is most useful when a peroneal tendon injury is suspected in conjunction with a CFL injury.

Ultrasonography has recently been advocated for evaluating acute ankle ligament injuries, but it has yet to be accepted as a proven imaging technique for this condition. Milz et al performed a study comparing the results of MRI and ultrasound in acute ankle sprains and demonstrated that ultrasound was almost as effective as MRI in differentiating between injured and intact ligaments. In a cross-sectional study by Lee and Yun, point-of-care ankle ultrasound proved to be as precise as MRI for detecting major ankle ligament and Achilles tendon injuries with acceptable sensitivity (96.4%–100%), specificity (95.0%–100%), and accuracy (96.5%–100%). Evaluation by ultrasound is highly operator dependent and has yet to be accepted in mainstream orthopaedics as an imaging modality of choice, but it can be done in the office and at less expense than an MRI.

At present, when a definitive diagnosis with objective documentation is important, MRI is the imaging method of choice. MRI has supplanted CT scans, arthrography, and tenography in evaluating ankle sprains because of its superior visualization of the ligaments, tendons, cartilage, and bony injuries with a single study ( Fig. 36-29 ). Numerous studies demonstrate periarticular hemorrhage, edema, and irregular, wavy, or disrupted lateral ligaments that correlate well with the clinical and surgical diagnoses. MRI allows for grading the extent of ligamentous injury and monitoring the healing process after treatment of ligament tears. One study found that MRI (1 tesla [T], standard imaging sequences, dedicated extremity coil) in comparison to arthroscopy was 100% sensitive for the diagnosis of ATFL and CFL tears as well as osteochondral injuries. The accuracy for diagnosis of ATFL tear was 91.7%, CFL tear, 87.5%, and osteochondral lesions (OCL), 83.3%. Sensitivity was low, especially for CFL tears. A similar study comparing arthroscopy to MRI (1.5 T, standard sequences, 150 × 150 mm field of view) reported similar low sensitivity: ATFL, 60%; OCL-talus, 46%; syndesmosis injury, 21%; synovitis, 21%; and anterior impingement caused by an osteophyte, 22%. Both studies concluded that arthroscopy may still be warranted in the symptomatic patient with negative results on MRI. The remaining uncertainties concerning MRI relate primarily to expense and how to use the MRI to predict which injuries will benefit from surgical intervention.