Ankle sprain

INTRODUCTION — Ankle injuries are among the most common injuries presenting to primary care offices and emergency departments [1]. Patients with ankle sprains (stretching, partial rupture, or complete rupture of at least one ligament) constitute a large percentage of these injuries.

Ankle ligaments provide mechanical stability, proprioceptive information, and directed motion for the joint. Recurrent ankle sprains can lead to functional instability and loss of normal ankle kinematics and proprioception, which can result in recurrent injury, chronic instability, early degenerative bony changes, and chronic pain [2]. Acute ankle sprains can result in lost days of work and inability to participate in sports.

This topic review will discuss ankle sprains. Ankle fractures are discussed elsewhere. (See "Overview of ankle fractures").

CLASSIFICATION OF ANKLE SPRAINS

Location — The mechanism of injury determines the location of the sprain.

Lateral ankle sprain — The most common mechanism of ankle injury is inversion of the plantar-flexed foot, which causes damage to the lateral ligament complex of the ankle. This ligament complex consists of the anterior talofibular ligament, the calcaneofibular ligament, and the posterior talofibular ligament (show figure 1). The ligaments within this complex are injured in a predictable sequence as forces increase.

The anterior talofibular ligament is the first or only ligament to be injured in the majority of ankle sprains. Stronger forces lead to combined ruptures of the anterior talofibular ligament and the calcaneofibular ligament, which can result in significant ankle joint instability. Isolated injury of the calcaneofibular ligament is uncommon. Yet stronger forces result in injury to all three ligaments. Such injuries, while uncommon, are more debilitating and more commonly associated with significant nerve injury [3].

Medial ankle sprain — The medial deltoid ligament complex (show figure 2) is the strongest of the ankle ligaments and is infrequently injured. Forced eversion of the ankle can cause damage to this structure but more commonly results in an avulsion fracture of the medial malleolus because of the strength of the deltoid ligament.

Syndesmotic sprain (high ankle sprain) — Dorsiflexion and/or eversion of the ankle may cause sprain of the syndesmotic structures, which include the anterior tibiofibular, posterior tibiofibular, and transverse tibiofibular ligaments, and the interosseous membrane (show figure 3). These structures are critical to ankle stability. Syndesmotic ligament injuries contribute to chronic ankle instability and are more likely to result in recurrent ankle sprain and the formation of heterotopic ossification [4]. Syndesmosis sprains range from 1 to 11 percent of all ankle sprains, with a higher rate of injury occurring in contact sports [5].

Grading — Ankle sprains have traditionally been classified based upon clinical signs and functional loss from grade I to grade III: A grade I sprain results from mild stretching of a ligament with microscopic tears. Patients have mild swelling and tenderness. There is no joint instability on examination, and the patient is able to bear weight and ambulate with minimal pain. Due to their benign nature, these injuries are not frequently seen in the office. A grade II sprain is a more severe injury involving an incomplete tear of a ligament. Patients have moderate pain, swelling, tenderness, and ecchymosis. There is mild to moderate joint instability on exam with some restriction of the range of motion and loss of function. Weight bearing and ambulation are painful. A grade III sprain involves a complete tear of a ligament. Patients have severe pain, swelling, tenderness, and ecchymosis. There is significant mechanical instability on exam and significant loss of function and motion. Patients are unable to bear weight or ambulate.

Although higher grade sprains involve more severe injuries to ligaments, the time for healing is not always proportional to the grade of the sprain.

CLINICAL EVALUATION

History — Evaluation of an injured ankle requires a careful history. It is important to determine: The mechanism of injury in order to direct the rest of the examination Whether or not the patient could walk after the injury in order to help stratify risk of fracture Whether or not the ankle had been previously injured, as people who sprain ankles are more likely to reinjure the same ankle; a study in basketball players found repeat ankle injuries almost five times as likely as primary injuries [6].

Physical examination — Physical examination of the ankle includes inspection, palpation, determination of weight-bearing ability, and injury-specific physical diagnostic tests. Look for swelling and ecchymosis. Palpate the entire fibula (a syndesmotic injury may be associated with a fracture of the proximal fibula — a Maisonneuve fracture), the distal tibia, the foot, and the Achilles tendon. The Thompson test should be performed if any tenderness or a tissue deficit is detected while palpating the Achilles tendon. (See "Posterior ankle tendinopathies").

Check for tenderness in the areas required for the Ottawa ankle rules (posterior edge or tip of the lateral malleolus; posterior edge or tip of the medial malleolus; base of the fifth metatarsal; navicular bone). (See "Ottawa ankle rules" below).

Tenderness of the distal tibia or fibula may represent fracture associated with inversion or eversion injuries (see "Ottawa ankle rules" below). Tenderness over the ligamentous structures is a non-specific finding but often indicates injury.

An eversion or hyperdorsiflexion injury associated with tenderness at the distal tibiofibular joint (show picture 1) without significant swelling may suggest a syndesmosis sprain.

Effusion and pain on palpation of the talocrural joint line (show picture 2) may suggest a fracture of the osteochondral talar dome resulting from direct trauma between the talus and the fibula or tibia. Check for pain on gentle passive inversion and eversion of the ankle. In lateral ankle sprains, pain is increased with forced ankle inversion, while the pain of a medial (deltoid) ligament sprain is accentuated by eversion of the ankle. Perform specific examination maneuvers (described below) including the squeeze test, the external rotation stress test, the anterior drawer test, and the talar tilt test.

If there is no swelling or ecchymosis, physical examination maneuvers do not elicit pain, and the Ottawa ankle criteria for imaging are not met (see "Ottawa ankle rules" below), there is unlikely to be structural damage.

Squeeze test — The squeeze test consists of compression of the fibula against the tibia at the mid-calf level. This maneuver elicits pain in the region of the anterior tibiofibular ligament (anterior to the lateral malleolus and proximal to the ankle joint) when a syndesmotic sprain has occurred (show picture 3).

External rotation stress test — The external rotation stress test can also help identify a syndesmotic sprain (show picture 4). The physician stabilizes the leg proximal to the ankle joint while grasping the plantar aspect of the foot and rotating the foot externally relative to the tibia. The test is positive if pain is elicited in the region of the anterior tibiofibular ligament (anterior to the lateral malleolus and proximal to the ankle joint).

Anterior drawer test — The anterior drawer test detects excessive anterior displacement of the talus on the tibia. If the anterior talofibular lateral ligament is torn by an inversion stress, the talus will sublux anteriorly and laterally out of the mortise. The test is performed with the patient's foot in the neutral position (slightly plantar flexed and inverted). The lower leg is stabilized by the examiner with one hand, and with the opposite hand, the examiner grasps the heel while the patient's foot rests on the anterior aspect of the examiner's arm. An anterior force is gently but steadily applied to the heel while holding the distal anterior leg fixed (show picture 5). The amount of movement should be compared to the uninjured side to determine joint laxity. This test has limited usefulness in the acute setting because pain, swelling, and muscle spasm may limit mobility of the joint and interfere with the test's reliability. It is a more helpful test in the evaluation of chronic ankle instability.

Talar tilt test — The talar tilt test detects excessive ankle inversion. If the ligamentous tear extends posteriorly into the calcaneofibular portion of the lateral ligament, the lateral ankle is unstable and talar tilt occurs. With the ankle in the neutral position, gentle inversion force is applied to the affected ankle, and the degree of inversion is observed and compared to the uninjured side (show picture 6). As with the anterior drawer test, this maneuver is of limited usefulness in the acute injury when pain, swelling, and muscle spasm are present, and it may be more important in evaluating chronic ankle instability.

Deferred exam — Deferred examination may improve the diagnosis of ligamentous injuries and instability. One study of 160 consecutive patients with inversion injuries found that performing a physical examination five days after the injury improved the accuracy of diagnosing ligament rupture [7]. The positive predictive value for ligament rupture of the triad of pain on palpation of the anterior talofibular ligament, lateral discoloration due to hematoma, and a positive anterior drawer sign was 95 percent.

Despite this, most patients with acute ankle injuries can be appropriately managed and triaged without performing a deferred examination.

RADIOGRAPHY

Imaging modality — Malleolar fractures, distal fibula fractures, talar dome fractures, and syndesmosis separation may be diagnosed with plain x-ray. If indicated, anteroposterior, lateral, and mortise x-rays should be obtained.

Stress radiography (obtaining plain films while performing a talar tilt or anterior drawer stress maneuver) is sometimes considered; however, it is rarely if ever clinically helpful [8].

In the setting of acute injury, magnetic resonance imaging (MRI) has no advantage over plain x-ray [9]. However, MRI should be considered in ankle sprains that are still painful after six to eight weeks of standard therapy. MRI can detect talar dome fractures and may be used to confirm suspected syndesmosis injury.

Selection of patients — While not well studied in the primary care setting, it is estimated that fracture of the ankle or midfoot occurs in less than 15 percent of patients presenting to an emergency department with an acute ankle sprain [10-14]. The Ottawa ankle rules were developed in an effort to reduce the number of unnecessary radiographs in such patients [15].

Ottawa ankle rules — The Ottawa ankle rules were developed, tested, and validated in adult patients presenting to the emergency department with acute ankle injuries. Although their use specifically in the primary care setting has not been assessed, the rules have demonstrated excellent results in both pediatric and adult emergency department patient populations.

A systematic review of 27 studies including 15,581 patients found that the Ottawa ankle rules were highly sensitive (96.4 to 99.6 percent) for excluding ankle fracture [16]. Specificity was modest and varied widely (10 to 79 percent), but the rules were purposely calibrated for high sensitivity at the expense of specificity. Less than 2 percent of patients who were negative for fracture according to the rules actually had a fracture. It was estimated that use of these rules in the emergency department for patients presenting with an acute ankle sprain would reduce the number of unnecessary radiographs by 30 to 40 percent. (See "Evaluation of foot and ankle pain in the young athlete", section on Radiologic evaluation).

Clinicians should remember that although multiple systematic reviews have found the Ottawa ankle rules to perform extremely well, as with any guidelines there are specific circumstances when clinical judgement should supersede them. As an example, patients with diminished peripheral sensation, such as diabetics, or intoxicated patients may need radiographs regardless of the Ottawa criteria. Missed fractures are a significant cause for litigation in the United States.

The rules are as follows (show figure 4):

An ankle series is only indicated for patients who have pain in the malleolar zone and Have bone tenderness at the posterior edge or tip of the lateral or medial malleolus

or
Are unable to bear weight both immediately after the injury and for four steps in the emergency department or doctor's office.

A foot series is only indicated for patients who have pain in the midfoot zone and Have bone tenderness at the base of the fifth metatarsal or at the navicular

or
Are unable to bear weight both immediately after the injury and for four steps in the emergency department or doctor's office.

The following apply to the use of the Ottawa ankle rules: If the patient can transfer weight twice to each foot (four steps), he or she is considered able to bear weight even if he or she limps. Palpate the distal 6 cm of the posterior edge of the fibula when assessing for bone tenderness.

A web teaching program for the rules is available online at: www.ohri.ca/programs/clinical_epidemiology/OHDEC/ankle_rule/default.asp

TREATMENT

Immediate therapy — All lateral ankle ligament sprains can be treated in a similar fashion. Initial management goals are to limit inflammation and swelling and to maintain range of motion. Early treatment includes RICE (rest, ice, compression, elevation) and early mobilization: Rest is achieved by limiting weight bearing by having patients use crutches until they are able to walk with a normal gait. Cryotherapy applied as ice or cold water immersion is recommended for 15 to 20 minutes every two to three hours for the first 48 hours or until swelling is improved, whichever comes first [17]. Compression to control and decrease swelling should be applied early, usually with an elastic bandage or a padded, contoured semi-rigid ankle brace (eg, Aircast). An elastic bandage is wrapped from the toes to the calf, with extra compression around the ankle provided by a "U" shaped piece of felt. One small trial showed improvement in ankle joint function at both 10 days and one month among patients using the Aircast compared with a standard elastic bandage [18]. The injured ankle should be kept elevated above the level of the heart to further alleviate swelling. Nonsteroidal antiinflammatory drugs (NSAIDs) are recommended, but one NSAID has not been shown in good studies to be better than another. NSAIDs have been found to be superior to placebo [19,20]; however, they have not been compared with non-NSAID analgesics such as acetaminophen, so it is not clear that the antiinflammatory effect itself is important. From the beginning, exercises including plantar flexion, dorsiflexion, and foot circles (show figure 5) should be done to maintain range of motion. Ankle splints or braces can limit extremes of joint motion and allow early weight bearing while protecting against reinjury (see "Splints and braces" below). The issue of whether severe ankle sprains should be immobilized with a plaster cast or ankle boot is discussed below (see "Immobilization" below).

Rehabilitation — Functional rehabilitation is of primary importance in aiding return to activity and preventing chronic instability. Early functional rehabilitation includes range of motion exercises (Achilles tendon stretch, foot circles (show figure 5), alphabet exercises [have the patient trace letters in the air with his big toe]), muscle strengthening exercises (isometric and isotonic plantar flexion, dorsiflexion, inversion, eversion, toe curls (show picture 7) and marble pickups, heel walks and toe walks), and proceeds to proprioceptive training (circular wobble board and walking on different surfaces) and activity-specific training (walk-jog, jog-run) [21,22].

In most patients, functional rehabilitation should begin on the day of injury and continue until the patient has returned to pain-free activity. The rehabilitation program should take several weeks in order for the ankle to strengthen and to limit the chance of reinjury. In a study of active-duty marines with grade II ankle sprains, those undergoing a structured rehabilitation program returned to duty up to several months earlier than those without rehabilitation [23].

Whether patients with severe sprains should have their ankle immobilized for a period of time prior to rehabilitation is controversial (see "Immobilization" below).

Splints and braces — During functional rehabilitation, it may be of benefit to use splints, braces, elastic bandages, or taping to try to reduce instability, protect the ankle from further injury, and to limit swelling.

A systematic review of nine randomized and quasi-randomized controlled trials that evaluated strategies for treatment of acute lateral ankle ligament injuries using different methods of ankle support during functional rehabilitation reported the following results [24]: Lace-up ankle supports were superior to semi-rigid ankle supports, elastic bandages, and tape in preventing persistent swelling. Semi-rigid ankle supports (show table 1) resulted in quicker return to work, quicker return to sports, and less instability at short-term follow-up than elastic bandages. Tape caused more skin irritation than elastic bandages.

Immobilization — Although patients with ankle sprains are sometimes treated with immobilization with a plaster cast or with a rigid boot prior to functional rehabilitation, most patients do not require immobilization.

A systematic review of 21 randomized and quasi-randomized trials found that functional rehabilitation was superior to immobilization on seven outcome measures: more patients returned to sport in the long term (RR 1.86, 95% CI 1.22-2.86); the time taken to return to work was shorter (4.9 days, CI 1.5-8.3); more patients had returned to work at short-term follow-up (RR 5.75, CI 1.01-32.71); the time taken to return to work was shorter (8.2 days, CI 6.3-10.2); fewer patients suffered from persistent swelling at short-term follow-up (RR 1.74, CI 1.17-2.59); fewer patients suffered from objective instability as tested by stress x-ray (2.60, CI 1.24-3.96); and patients treated functionally were more satisfied with their treatment (RR 1.83, CI 1.09-3.07) [25]. The systematic review found that many trials were of poor quality, and there was variety among the functional treatments evaluated. In a separate analysis of the higher quality trials, the only significant result was that patients treated with functional rehabilitation returned to work sooner than those treated with immobilization (12.9 days, CI 7.1-18.7).

The treatment of Grade III ankle sprains, in particular, remains controversial. The systematic review discussed above did not stratify patients to look at a subset of patients with more severe ankle injuries. One of the trials included in the systematic review assigned 80 patients with grade III lateral ligament ruptures to immobilization in a plaster cast or early mobilization with a stabilizing orthosis. Patients treated with early mobilization resumed work and sports earlier than immobilized patients, and there were no differences in ankle stability or symptoms during activity after one year of follow-up. Given these results, it appears likely that early functional rehabilitation is superior to immobilization even in patients with Grade III ankle sprains.

Surgery — Surgical repair of ruptured ankle ligaments is sometimes considered in patients with ankle sprains. A meta-analysis that looked at controlled trials of surgery for acute ruptures of lateral ankle ligaments found that compared with functional treatment, patients treated with surgery were significantly less likely to experience giving-way of the ankle (relative risk 0.23, 95% CI 0.17-0.31) [26]. A subsequent systematic review concluded that there were methodologic flaws in all trials making it impossible to determine the relative effectiveness of surgical and conservative treatment for sprains of the lateral ankle ligaments [27].

A subsequent prospective trial of therapy for lateral ankle ligament rupture allocated 185 patients to surgery and 203 patients to functional treatment based upon the week in which they presented [28]. After a median follow-up of eight years, fewer patients treated surgically than with functional treatment reported residual pain (16 versus 25 percent), symptoms of giving-way (20 versus 32 percent), and recurrent sprains (22 versus 34 percent). There was no difference in the percent of patients with worsening radiographic evidence of joint degeneration. At follow-up, patients treated surgically were less likely to have a positive anterior drawer test (30 versus 54 percent); however, this was assessed by clinicians who knew how the patients had been treated. Thus, there were no blinded objective assessments in this trial that demonstrated superiority of surgery.

Based on these results, it is unclear whether patients with acute ankle sprains would benefit from surgery. Given costs and operative risks, it is unlikely that most patients with mild or moderate ankle sprains will be treated surgically. It may be reasonable to consider surgery in some patients with severe sprains who are engaged in professional sports or other activities that are likely to impose repeated large stresses on the ankle joint.

Although many experts conclude that delayed operative reconstruction of injured ligaments achieves results similar to that with acute repair [26], we are not aware of any head-to-head trials that examine this issue.

Other therapy — Neither ultrasound therapy [29], low-level laser therapy [30], or hyperbaric oxygen therapy [31] appear to be effective in the treatment of ankle sprains.

REFERRAL — Indications for referral to an orthopedic surgeon include: Fracture Dislocation or subluxation Syndesmosis injury Tendon rupture Wound penetrating into the joint Uncertain diagnosis

Patients with neurovascular compromise (distal findings of decreased sensation, motion, or circulation) require emergent evaluation.

PREVENTION — Options for primary or secondary prevention of ankle injuries include external ankle supports such as semi-rigid orthoses (show table 1), lace up supports, and high-top shoes, taping, stretching, strengthening, and proprioceptive ankle training using a wobble board.

A systematic review of 14 randomized trials concluded that patients treated with external ankle supports had a reduced risk of sprain (RR 0.53, 95% CI 0.40-0.69); however, the protective effect of high-top shoes, in particular, has not been established [32]. The reduction in risk was greater for those with a previous ankle sprain than in primary prevention. External supports did not appear to alter the severity of ankle sprains that did occur or change the incidence of other leg injuries. The authors concluded that further research was needed comparing various external ankle supports and on interventions such as taping, strengthening, and proprioceptive training.

A meta-analysis of eight studies that looked at prevention of ankle sprains found variability in study methodology and design, but concluded that while ankle braces and taping both appeared to be somewhat effective, braces appeared to be superior to taping [33]. Proprioceptive training appeared to be equally effective in primary and secondary prevention of ankle injuries.

Athletes may have concerns about decreased performance with external ankle supports. A study that looked at running and jumping performance found differing results depending on the specific brace or method (such as taping) used, but in no case did a support decrease performance by more than 5 percent [34].

Two randomized controlled trials conducted with high school and young adult athletes found that proprioceptive balance training reduced the incidence of ankle sprains among players with prior ankle sprains [35,36].

SUMMARY AND RECOMMENDATIONS — The mechanism of most ankle sprains is an inversion injury to the lateral ligaments of the ankle.

For patients presenting with an acute ankle injury: Perform a careful history to determine the mechanism of injury (to direct the examination), whether the patient could walk after the injury (important for the Ottawa ankle rules), and whether the ankle had been previously injured (patients with a history of ankle sprains are at increased risk for new sprains). Perform a careful physical examination, with particular attention to the areas covered by the Ottawa ankle rules (see "Ottawa ankle rules" above). To rule out an ankle fracture, obtain anteroposterior, lateral, and mortise plain films of the ankle, if indicated by the Ottawa ankle rules (see "Ottawa ankle rules" above). Start functional rehabilitation with rest, ice, compression, elevation (RICE), early mobilization, and support orthosis with early weight bearing. Referral to a physical therapist for advanced functional rehabilitation may be helpful. Patients with a positive squeeze test or positive external rotation stress test may have a syndesmosis injury. Syndesmosis injury can be confirmed with MRI. Patients with a syndesmosis injury should be referred to an orthopedic surgeon.

For patients with persistent symptoms: Consider obtaining an MRI in patients with symptoms that persist for more than six to eight weeks to rule out conditions such as talar dome fractures or syndesmosis injury. Consider referral to an orthopedic surgeon for patients with chronic ankle instability.

For prevention of reinjury in patients with a history of ankle sprain: Institute proprioceptive balance board training, possibly under the guidance of a physical therapist.

REFERENCES

1. Boruta, PM, Bishop, JO, Braly, WG, Tullos, HS. Acute lateral ankle ligament injuries: a literature review. Foot Ankle 1990; 11:107.
2. Anandacoomarasamy, A, Barnsley, L. Long term outcomes of inversion ankle injuries. Br J Sports Med 2005; 39:e14;.
3. Nitz, AJ, Dobner, JJ, Kersey, D. Nerve injury and grades II and III ankle sprains. Am J Sports Med 1985; 13:177.
4. Taylor, DC, Englehardt, DL, Bassett, FH III. Syndesmosis sprains of the ankle: The influence of heterotopic ossification. Am J Sports Med 1992; 20:146.
5. Trojian, TH, McKeag, DB. Ankle sprains: expedient assessment and management. Physician and Sportsmedicine 1998; 26:10. www.physsportsmed.com/issues/1998/10Oct/mckeag.htm (Accessed June 10, 2005).
6. McKay, GD, Goldie, PA, Payne, WR, Oakes, BW. Ankle injuries in basketball: injury rate and risk factors. Br J Sports Med 2001; 35:103.
7. van Dijk, CN, Lim, LS, Bossuyt, PM, Marti, RK. Physical examination is sufficient for the diagnosis of sprained ankles. J Bone Joint Surg Br 1996; 78:958.
8. Frost, SC, Amendola, A. Is stress radiography necessary in the diagnosis of acute or chronic ankle instability?. Clin J Sport Med 1999; 9:40.
9. Nikken, JJ, Oei, EH, Ginai, AZ, et al. Acute ankle trauma: value of a short dedicated extremity MR imaging examination in prediction of need for treatment. Radiology 2005; 234:134.
10. Brand, DA, Frazier, WH, Kohlhepp, WC, et al. A protocol for selecting patients with injured extremities who need x-rays. N Engl J Med 1982; 306:333.
11. Brooks, SC, Potter, BT, Rainey, JB. Inversion injuries of the ankle: clinical assessment and radiographic review. Br Med J (Clin Res Ed) 1981; 282:607.
12. Dunlop, MG, Beattie, TF, White, GK, et al. Guidelines for selective radiological assessment of inversion ankle injuries. Br Med J (Clin Res Ed) 1986; 293:603.
13. Lloyd, S. Selective radiographic assessment of acute ankle injuries in the emergency department: barriers to implementation. CMAJ 1986; 135:973.
14. Sujitkumar, P, Hadfield, JM, Yates, DW. Sprain or fracture? An analysis of 2000 ankle injuries. Arch Emerg Med 1986; 3:101.
15. Stiell, IG, Greenberg, GH, McKnight, RD, Nair, RC. Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation. JAMA 1993; 269:1127.
16. Bachmann, LM, Kolb, E, Koller, MT, et al. Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review. BMJ 2003; 326:417.
17. Sloan, JP, Hain, R, Pownall, R. Clinical benefits of early cold therapy in accident and emergency following ankle sprain. Arch Emerg Med 1989; 6:1.
18. Boyce, SH, Quigley, MA, Campbell, S. Management of ankle sprains: a randomised controlled trial of the treatment of inversion injuries using an elastic support bandage or an Aircast ankle brace. Br J Sports Med 2005; 39:91.
19. Moran, M. Double-blind comparison of diclofenac potassium, ibuprofen and placebo in the treatment of ankle sprains. J Int Med Res 1991; 19:121.
20. Slatyer, MA, Hensley, MJ, Lopert, R. A randomized controlled trial of piroxicam in the management of acute ankle sprain in Australian Regular Army recruits. The Kapooka Ankle Sprain Study. Am J Sports Med 1997; 25:544.
21. Wolfe, MW, Uhl, TL, Mattacola, CG, McCluskey, LC. Management of ankle sprains. Am Fam Physician 2001; 63:93.
22. Wester, JU, Jespersen, SM, Nielsen, KD, Neumann, L. Wobble board training after partial sprains of the lateral ligaments of the ankle: a prospective randomized study. J Orthop Sports Phys Ther 1996; 23:332.
23. Weinstein, ML. An ankle protocol for second-degree ankle sprains. Mil Med 1993; 158:771.
24. Kerkhoffs, GM, Struijs, PA, Marti, RK, et al. Different functional treatment strategies for acute lateral ankle ligament injuries in adults. Cochrane Database Syst Rev 2002; :CD002938.
25. Kerkhoffs, GM, Rowe, BH, Assendelft, WJ, et al. Immobilisation and functional treatment for acute lateral ankle ligament injuries in adults. Cochrane Database Syst Rev 2002; :CD003762.
26. Pijnenburg, AC, Van Dijk, CN, Bossuyt, PM, Marti, RK. Treatment of ruptures of the lateral ankle ligaments: a meta-analysis. J Bone Joint Surg Am 2000; 82:761.
27. Kerkhoffs, GM, Handoll, HH, de Bie, R, et al. Surgical versus conservative treatment for acute injuries of the lateral ligament complex of the ankle in adults. Cochrane Database Syst Rev 2002; :CD000380.
28. Pijnenburg, AC, Bogaard, K, Krips, R, et al. Operative and functional treatment of rupture of the lateral ligament of the ankle. A randomised, prospective trial. J Bone Joint Surg Br 2003; 85:525.
29. Van Der, Windt DA, Van Der, Heijden GJ, Van Den, Berg SG, et al. Ultrasound therapy for acute ankle sprains. Cochrane Database Syst Rev 2002; :CD001250.
30. de Bie, RA, de Vet, HC, Lenssen, TF, et al. Low-level laser therapy in ankle sprains: a randomized clinical trial. Arch Phys Med Rehabil 1998; 79:1415.
31. Bennett, M, Best, T, Babul, S, et al. Hyperbaric oxygen therapy for delayed onset muscle soreness and closed soft tissue injury. Cochrane Database Syst Rev 2005; :CD004713.
32. Handoll, HH, Rowe, BH, Quinn, KM, de Bie, R. Interventions for preventing ankle ligament injuries. Cochrane Database Syst Rev 2001; :CD000018.
33. Verhagen, EA, van Mechelen, W, de Vente, W. The effect of preventive measures on the incidence of ankle sprains. Clin J Sport Med 2000; 10:291.
34. Burks, RT, Bean, BG, Marcus, R, Barker, HB. Analysis of athletic performance with prophylactic ankle devices. Am J Sports Med 1991; 19:104.
35. Verhagen, E, van der, Beek A, Twisk, J, et al. The effect of a proprioceptive balance board training program for the prevention of ankle sprains: a prospective controlled trial. Am J Sports Med 2004; 32:1385.
36. McGuine, TA, Keene, JS. The effect of a balance training program on the risk of ankle sprains in high school athletes. Am J Sports Med 2006; 34:1103.