Ankle Sprains
Ken Stephenson, MD

Ankle sprains make up about 15% of all athletic injuries, with a reported 23,000 ankle ligament injuries occurring each day in the United States. They are particularly common in basketball, volleyball, soccer, modern dance, and ballet. Most patients fully recover, but an estimated 20 to 40% develop chronic symptoms of pain and instability.

Relevant Anatomy
The stability of any joint depends on the inherent constraints provided by the bony configuration and the active and passive soft tissue restraints. The ankle joint is quite stable in the neutral position because the wider anterior portion of the talus fits snugly into the ankle mortise. Plantar flexion of the ankle rotates the narrower posterior talus into the mortise, resulting in a much looser fit, with a particular tendency toward inversion. Active soft tissue restraint depends on the muscle-tendon units involved in movement and support of the joint. The talus, however, has no tendinous insertions and must rely in an indirect way on the muscular actions on other bones adjacent to the ankle joint. Passive support of the ankle is provided by the medial, lateral, and posterior ligaments and the syndesmosis. The lateral ankle ligament complex is the structure most commonly involved in ankle sprains.

The three main components of the lateral ligament complex are the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL) (Fig. 5–1). The ATFL is relaxed in neutral and taut in plantar flexion. It is the primary restraint against inversion while the foot is plantar flexed. The CFL is also relaxed in neutral, but it is taut in dorsiflexion.

The most common ankle injury involves an isolated tear of the ATFL, followed by a combined tear of the ATFL and the CFL. The mechanism of injury is usually inversion of the plantar flexed foot (Fig. 5–2).

Classification of Lateral Collateral Ligament Sprains
A grade 1, or mild ankle sprain, is a stretch of the ligament with no macroscopic tear, little swelling or tenderness, minimal or no functional impairment, and no joint instability. A grade 2, or moderate ankle sprain, involves a partial tear of the ligament with moderate swelling and tenderness, some loss of joint function, and mild joint instability. A grade 3, or severe sprain, involves a complete tear of the ligaments (ATFL and CFL) with severe swelling, ecchy-mosis and tenderness, inability to bear weight on the extremity, and mechanical joint instability (Fig. 5–3).

Diagnosis
An inversion injury is commonly associated with a tearing sensation or a pop felt by the patient over the lateral ankle. Swelling can be immediate in grades 2 and 3 sprains, and the initial intense pain subsides after a few hours, only to return more intensely as the hemorrhage continues 6 to 12 hours after the injury.

Physical Examination
Physical examination reveals mild swelling in grade 1 sprains and moderate to severe swelling in a diffuse pattern in grades 2 and 3 sprains. Tenderness is usually elicited at the anterior edge of the fibula with ATFL injuries and at the tip of the fibula with CFL injuries. The region of the syndesmosis and the base of the fifth metatarsal should also be palpated to rule out injuries to these structures.

The anterior drawer test and the talar tilt test are commonly used to identify signs of joint instability (Fig. 5–4 A and B). The anterior drawer test is performed by stabilizing the distal tibia anteriorly with one hand and pulling the slightly plantar flexed foot forward with the other hand from behind the heel. A positive finding of more than 5 mm of anterior translation indicates a tear of the ATFL. The talar tilt test is performed by stabilizing the distal tibia with one hand and inverting the talus and calcaneus as a unit with the other hand. A positive finding of more than 5 mm with a soft endpoint indicates a combined injury to the ATFL and CFL (see Fig. 5–4C). It is important to always compare the affected ankle with the contralateral side because some patients are naturally very flexible (generalized ligamentous laxity), and this could result in a false-positive test.

Syndesmosis Injury
Disruption of the syndesmosis ligament complex (tibiofibular ligaments and interosseous membrane) may occur in as many as 10% of all ankle ligament injuries (Fig. 5–6). The examiner should always test for this injury (see squeeze test and external rotation test, p. 377). Rupture of the syndesmosis is often associated with deltoid (medial) ligament rupture, and concomitant fracture of the fibula is common (see ankle fracture section). The mechanism may be pronation and eversion of the foot combined with internal rotation of the tibia on a fixed foot, such as occurs in football players who have an external rotation force applied to the foot (stepped on) while lying prone on the field.

Point tenderness and pain are located primarily on the anterior aspect of the syndesmosis (not over the lateral collaterals as with an ankle sprain), and the patient is usually unable to bear weight. These injuries are typically more severe than ankle sprains, with more pain, swelling, and difficulty in weight-bearing. Stress radiographs taken with the ankle in external rotation (in both dorsiflexion and plantar flexion) often display the diastasis (gap) between the tibia and the fibula. Bone scanning is useful if the diagnosis is suspected but hard to confirm.

Partial isolated syndesmosis tears are typically treated nonoperatively in a removable cast for 6 to 8 weeks (partial weight-bearing with crutches). With complete syndesmosis rupture, the fibula may shorten and externally rotate. A complete tear is treated by suture of the ligament and temporary fixation of the tibia and fibula with a syndesmosis screw. The syndesmosis screw must be placed with the ankle dorsiflexed to neutral (the widest portion of the talus) to avoid postoperative limited dorsiflexion. A walking boot is used (touch-down weight-bearing) for 6 to 8 weeks postoperative. Early active and passive motion out of the boot is encouraged from day 7, and full weight-bearing is allowed at 6 weeks. An aggressive rehabilitation program stressing vigorous range of motion (ROM), strengthening, and proprioception exercises is undertaken (see ankle sprain rehabilitation protocol, p. 381). The patient should be informed about the longer recovery compared with ankle sprains and the potential for pain and late sequelae, such as heterotopic ossification.

Factors crucial for a good outcome after syndesmosis injuries are recognition of the injury and obtaining and maintaining an anatomic reduction of the ankle mortise and the distal lower extremity syndesmosis. Syndesmosis fixation is usually indicated to avoid the more catastrophic complications of mortise widening and joint incongruity (e.g., early post-traumatic arthritis).

Radiographic Evaluation
Radiographs are taken to rule out fractures of the medial and lateral malleoli, the talus, and the fifth metatarsal base. Radiographs should include three views of the ankle on long cassettes that include the entire length of the fibula: anteroposterior [AP], lateral, and mortise views (Fig. 5–7A) and three views of the foot (AP, lateral, and oblique) (see Fig. 5–7B–D). Stress radiographs can be used to quantify instability during the anterior drawer and talar tilt stress tests. Anterior taluar subluxation of more than 10 mm or more than 5 mm difference from the contralateral ankle indicates a positive anterior drawer stress test. Talar tilt of 15 degrees or 10 degrees difference from the contralateral ankle indicates a positive talar tilt test.

Treatment for Lateral Collateral Sprains
The current literature supports functional rehabilitation as the preferred method of treatment for ankle sprains, allowing an earlier return to work and physical activity without a higher rate of late symptoms (ankle instability, pain, stiffness, or muscle weakness) when compared with cast immobilization.

Immediately after injury in the acute phase, the PRICE (protection, rest, ice, compression, and elevation) principle is followed (see rehabilitation protocol). The goal is to reduce hemorrhage, swelling, inflammation, and pain. A period of immobilization is initiated, depending on the severity of the injury. Some authors stress the importance of immobilizing the ankle in neutral rather than in plantar flexion because the ATFL is stretched out during plantar flexion. For grades 1 and 2 sprains, an ankle brace (Fig. 5–8) is used for immobilization. For grade 3 sprains, a removable cast boot offers more stability and protection and allows earlier weight-bearing with less pain. Immobilization is continued for several days in mild sprains and up to 3 weeks in severe grade 3 sprains. As grade 3 sprains improve, the cast boot is replaced with an ankle brace.

In the subacute phase, goals include continued reduction of swelling, inflammation, and pain, while some motion, strengthening, and appropriate controlled weight-bearing are started. This is the period of collagen fiber proliferation, and too much stress on the ligaments at this point could result in weaker tissue.

The rehabilitative phase focuses on improving strength, endurance, balance, and weight-bearing proprioception. During this maturation phase of the healing ligament, about 3 weeks after the injury, controlled stretching of the muscles and movement of the joint promote a more normal orientation of the collagen fibers parallel with the stress lines. Repeated exercise during this phase has been shown to increase the mechanical and structural strength of the ligaments.

Prevention of Ankle Sprains
Proper strengthening and rehabilitation are critical to help prevent inversion ankle injuries; however, some patients require additional biomechanical support. We routinely use ankle braces in athletes prone to ankle injuries in high-risk sports like basketball and volleyball. We prefer a lace-up brace with figure-of-eight straps or a functional stirrup brace that is placed beneath the insole of the shoe. The Ultimate Ankle Brace (Bledsoe Brace Company) effectively limits inversion injuries, but still allows the ankle to dorsiflex and plantar flex. However, some athletes, such as ballet dancers, may not be able to perform in a brace, which limits its usefulness in some sports. Another effective means of preventing inversion injuries is to apply a slight lateral flare to the sole of the tennis shoe or a lateral wedge to an insole. This, again, is effective only in certain sports in which a tennis shoe is worn.

Ankle taping may be of some benefit, but much of the strength is lost with loosening of the tape within the first 10 minutes. We use a closed basketweave technique (Fig. 5–16).
1.       Have the seated athlete position the ankle at 90 degrees (A.)
2.       Spray a tape adherent (e.g., Tuf-Skin, QDA) over the area to be taped.
3.       Apply a heel and lace pad with skin lubricant on the anterior and posterior aspects of the ankle (B.)
4.       Apply pre-wrap, starting at the midfoot and continuing up the leg, overlapping by half until approximately 5–6 inches above the medial malleolus (C.)
5.       Apply an anchor strip at the proximal (#1) and distal (#2) ends of the pre-wrap with half of the tape covering the pre-wrap and the other half adhering to the skin (D.)
6.       Starting posteromedially on the proximal anchor, apply a stirrup covering the posterior third of the medial malleolus and then under the foot and up the lateral side to the proximal anchor (#3) (Ei and ii).
7.       Starting at the distal anchor (#4), apply a horseshoe around the heel (approximately 2 inches from the plantar surface) to the other side of the distal anchor (F.)
8.       Repeat steps 6 and 7 twice. Each time, overlap the previous strip by half the width of the tape (G.)
9.       To apply a figure-of-8, start medially (Hi) at the position of the first stirrup (#5), pull the tape at an angle toward the medial longitudinal arch (approximately where the third stirrup goes under the foot), under the foot, across the anterior aspect of the ankle, and around the ankle (just above the third horseshoe strip) (Hii).
10.     Close up the tape by applying single strips of tape around the leg, overlapping by half until the area from the ankle to the proximal anchor is covered (#6) (I).
11.     To apply a heel lock, start at the anterior aspect of the proximal anchor laterally. Pull the tape at an angle (arrows) toward the posterior aspect of the lateral malleolus, around the posterior aspect of the ankle, under the heel, up the lateral side of the foot, and across the anterior aspect of the ankle (Ji–iii). To continue and apply a continuous double-heel lock, make one complete loop around the ankle (#7), continue around the ankle, then down around the posterior aspect of the ankle, under the heel, and up the medial side of the foot (K), across the anterior aspect of the ankle, and complete with another full loop around the ankle.
12.     Apply one or two closure strips (dark tape) around the foot (#8) to hold the horseshoes down to the foot and the anchor strip (Li–v).

Chronic Lateral Ankle Instability: Rehabilitation after Lateral Ankle Ligament Reconstruction
Mark Colville MD, and Ken Stephenson, MD
It is estimated that 20 to 40% of patients with ankle sprains develop long-term sequelae such as pain, swelling, or instability. Interestingly, the severity of the ankle sprain does not seem to correlate with the development of chronic symptoms. If a patient has received appropriate treatment for an ankle sprain and has completed a rehabilitation program but continues to have significant symptoms, another etiology of the symptoms must be sought. Etiologies to be considered in patients with chronic ankle pain include occult bony injuries such as fractures, osteochondral defects, or bone contusions; cartilage damage; ankle, subtalar, or syndesmosis instability secondary to ligament rupture; tendon pathology such as a peroneal tendon or posterior tibial tendon longitudinal tear; a neuropraxia of the superficial peroneal or sural nerves; or soft tissue problems such as anterolateral ankle soft tissue impingement.

Radiographic Examination
If the patient has a history or examination consistent with instability, stress radiographs (talar tilt and anterior drawer) are indicated. Although there is some controversy in the literature regarding normal values for stress radiographs, in general, a positive talar tilt is more than 15 degrees or more than 10 degrees difference from the contralateral side. A positive anterior drawer is 5 to 10 mm anterior subluxation of the talus or more than 5 mm difference from the contralateral side. MRI is useful for delineating bone contusions, avascular necrosis, osteochondral defects, and tendon or ligament injuries. The diagnosis of chronic lateral ankle ligament instability is based on a history of multiple inversion ankle sprains, often with fairly minor provocation (such as stepping off a curb). Instability, not pain alone, should be the primary criterion for ligament reconstruction.

Ankle Ligament Reconstruction
Numerous surgical procedures have been described for lateral ankle instability, but the most commonly used is the modified Brostrom procedure. This involves an anatomic repair of the ATFL and CFL augmented by suture of the superior edge of the inferior peroneal retinaculum to the anterior edge of the fibula. This procedure is particularly indicated in ballet dancers or patients whose livelihood depends on a full ROM and in most patients undergoing reconstruction for the first time. It is not the procedure of choice for revision surgery or patients with generalized ligamentous laxity or a connective tissue disorder. The use of the peroneus brevis tendon to augment the repair is indicated for revision surgery. The Watson-Jones, Chrisman-Snook, and Evans procedures have good success rates (80 to 85%) but each limits subtalar and ankle motion.

The goal of ankle ligament reconstruction in an unstable ankle is to restore stability while preserving normal ankle and subtalar motion whenever possible. Most patients with chronic instability have laxity of the ATFL and CFL and increased subtalar joint motion.

General Principles of Rehabilitation after Ankle Ligament Reconstruction
Postoperatively, a short-leg, well-padded splint is applied with the ankle in slight eversion, and the patient remains non–weight-bearing. One to 2 weeks after surgery, the patient is placed into a removable cast boot or short-leg walking cast with the foot in neutral position and is allowed to begin partial weight-bearing, progressing to full weight-bearing as tolerated. Four weeks postoperative, the patient is placed into a functional brace or removable cast boot, and active rehabilitation is started with gentle ROM exercises and isometric strengthening exercises. Usually at 6 weeks, proprioception and balancing exercises are started. In athletes, sport-specific exercises are started at about 8 weeks postoperative. Return to sports or dancing is allowed when peroneal strength is normal and the patient is able to perform multiple single-leg hops on the injured side without pain. A lace-up brace (such as the Rocket Sock) or functional stirrup brace should be worn for at least the first season, and most athletes prefer bracing or taping for sports indefinitely.