Ankle and Midfoot Fractures and Dislocations

Introduction

Fractures and dislocations of the foot are among the most common injuries in the musculoskeletal system. Sports-related lower limb fractures and dislocation are less frequent than those of the upper limb, but they are particularly problematic for athletes because they often result in significant periods of non-weight rehabilitation. The disability and time away from sports resulting from these injuries warrant close attention to diagnosis and management.

Clinical Evaluation

In evaluating patients with trauma to the ankle, it is essential to obtain a thorough, detailed history to direct the physical and radiographic examination.

Physical examination should be meticulous and systematic. Because of the high incidence of coexisting injuries or fracture/dislocations in the injured limb, careful examination and palpation of points of tenderness should be performed to detect evidence of occult injury. Evaluation of range of motion of the ankle, subtalar, mid-tarsal, and metatarsophalangeal joints is incorporated into every routine examination. A careful motor examination, both intrinsic and extrinsic, as well as a sensory examination are performed. Vascular examination, including Doppler studies, is essential. Radiographs are guided by the examiner’s history and physical examinations. Oftentimes, the injured athlete is unable to localize the injured part, so a more global radiographic survey is performed. Standard views of the foot include anteroposterior (AP), lateral, and oblique views. The oblique view, for example, is particularly useful for evaluating joints, such as the calcaneal cuboid joint, that typically are hidden or poorly examined in AP view. Specialty views, such as axial views of the heel, Broden’s view of the subtalar joint, and stress views of the foot, also are helpful in certain circumstances. Because of the complexity of the anatomy and lack of uniform appreciation or interpretation of the foot and ankle radiographs, adjunctive studies, such as computed tomography (CT), bone scan, and magnetic resonance imaging (MRI), can be of tremendous value. These also are particularly useful because of the subtle nature of many foot and ankle injuries.

Radiographic Evaluation

Standard radiographic examination of the ankle includes three views: AP, lateral, and mortise. These radiographs allow the clinician a clear view of the relationship of the three bones that comprise the ankle mortise—tibia, fibula, and talus. The use of measurements of mortise width; medial or tibiofibular clear space; talocrural angle; “Shenton’s” line of the ankle (that space that demonstrates a mirrored congruity between the lateral talar wall and the corresponding curvature of the distal medial fibula); and talar tilt all are helpful in determining the subtle abnormalities of the ankle mortise ( Fig. 6.1 ). When in doubt, the clinician also may obtain contralateral views to determine that which constitutes normal anatomy for that particular patient, because there tends to be a high degree of variability in what is considered normal from patient to patient.

Mortise views should demonstrate relative congruity of the joint space circumferentially—medial tibiotalar, dorsal tibiotalar, and lateral fibulotalar. The distance between these subchondral bone margins should be equivalent. In addition, a congruous relationship should exist between lateral talus and medial fibula, the so-called Shenton’s line of the ankle. Abnormalities, as evidenced by incongruity, provide clues to malalignment resulting from bony or soft tissue injury.

The medial clear space of the ankle as viewed on AP or mortise radiographs is the distance between the medial talar wall and lateral portion of medial malleolus. The measurement of the medial clear space continues to play a significant role in determining the stability of ankle fractures, and thus the need for operative interventions. Although this is a linear measure, it reflects a rotational (external) abnormality of the talus with respect to the tibia. Injury leading to abnormality of this relationship with measurements of less than 1 mm or greater than 4 mm has been shown to correlate with poor outcomes, including chronic pain, instability, and arthrosis. There remains significant variability in the literature with respect to the correct method of measuring the medial clear space. It is our practice to measure the medial clear space on a weight bearing or external rotation stress mortise view at a level 5 mm below the medial talar dome. It is imperative that the ankle is not plantar flexed in radiographs in which the medial clear space is evaluated, as the narrower posterior talar dome will often produce a falsely elevated measurement of medial clear space widening.

The talocrural angle helps to define the appropriate fibular length. This is measured as the angle between the line parallel to the distal tibial joint surface and another line drawn between tips of the medial and lateral malleoli. Normal values average 83 ± 4 degrees. Differences of more than 2 degrees to the contralateral normal side suggest fibular shortening.

Talar tilt is measured by determining the angle between articular surface lines drawn parallel to the distal tibia and proximal talus. Although uniform agreement on what is considered normal does not exist, a side-to-side difference of more than 5 degrees (or 2 mm) is considered pathologic.

Syndesmotic space probably is the most confounding of all radiologic measures. Measurements should be performed to account for the space existing between the medial edge of the fibula and the lateral edge of the tibial incisura, determined at 1 cm proximal to the joint line to ensure reproducibility. Average distance should be less than 5 mm but may vary up to 6 mm in larger individuals. Another measure of syndesmotic integrity is the tibiofibular overlap. The distance between the medial fibula and the lateral edge of the anterior tibia should be 10 mm (see Fig. 6.1 ).

Ancillary studies, such as CT scanning and MRI, are used liberally to provide more information regarding ankle relationships and stability.

Treatment

Generic goals in the treatment of fractures and dislocations of the ankle are as follows:

• Avoiding stiffness and loss of mobility.

• Removing bony prominences, which may result in pressure phenomena.

• Restoring the articular surfaces.

Any fracture or dislocation of the foot or ankle that results in focal skin pressure or evidence of neurovascular compromise must be addressed immediately. Manipulation or even open reduction must be carried out to reduce the potential sequelae, including skin necrosis, neuropraxia, ischemia, and/or pressure-induced necrosis of articular surfaces, because of abnormal loading secondary to malpositioning after fracture or dislocation.

Even anatomic restoration does not guarantee optimal functional outcome, but it certainly provides the athlete with a significantly reduced risk of morbidity associated with sequelae of delayed or untreated injury. However, injuries that present without gross distortion of anatomy or imminent threat to the viability of the limb may be treated better after an appropriate “cooling down” period. This is not to say that they should be splinted and ignored, but a short period should be devoted to rest, ice, compression, and elevation (RICE) to allow the soft tissue integrity and oxygenation to reestablish itself, particularly before the clinician embarks on any invasive procedures.

The evolution of treatment of the traumatized ankle of the athlete has directed more attention to aggressive intervention than to “benign neglect.” Recognition of the fact that long periods of immobilization after trauma may lead to muscular atrophy, myostatic contracture, reduction of joint mobility, associated connective tissue proliferation leading to scarring, synovial adhesion, and cartilage degeneration has prompted a more aggressive approach to ankle injuries, using appropriate surgical intervention to stabilize injuries and institute earlier range of motion and weight bearing when possible. These tenets provide for the ability to institute potential prevention against previously disabling factors such as disuse osteopenia, limb atrophy, proprioceptive losses, and chronic, persistent pain. Introduction of early range of motion, physical therapy modalities, appropriate splinting, and bracing, as opposed to casting, allows for the earlier restoration of function and avoidance of complications. The static accumulation of hematoma, fluid extravasation, and resultant articular and tendinous adhesions is far less with treatment that promotes earlier rehabilitation. This type of treatment also helps to prevent disabling sequelae, such as arthrofibrosis and regional pain syndromes.

Although the realm of athletically related ankle injuries is too vast to be encompassed in this chapter, the more common injury patterns encountered are addressed. Diagnostic and management controversies are discussed and elucidated for the reader. Rather than a trauma compendium, this is meant to be a guide for the treatment of frequently occurring sports and athletic injuries to the ankle for one’s reference and perusal.