Fig. 13.1
Lace-up or gauntlet style braces are usually made of canvas or nylon material. (Courtesy of Swede-O Inc., North Branch, MN)
Fig. 13.2
Stirrup ankle braces comprise semirigid plastic uprights which are oriented along the distal fibula and tibia and extend across the ankle joint to the medial and lateral aspect of the body of the calcaneus. (Air-stirrup ankle brace, Aircast, courtesy of DJO, Inc., Vista, CA)
A newer variation of the standard ankle stirrup brace is the articulated stirrup brace. Here a hinge connects a foot plate to the limb uprights at the level of the ankle joint (see Figs. 13.3 and 13.4). The foot plate of an articulated stirrup ankle brace does not cover a substantial portion of the foot; usually extending from the heel to the proximal arch.
Fig. 13.3
A newer variation of the standard ankle stirrup brace is the articulated stirrup brace. Here a hinge connects a foot plate to the limb uprights at the level of the ankle joint. (Courtesy of Swede-O Arch Lok, Swede-O Inc., North Branch, MN)
Fig. 13.4
(a–c) Ambulatory ankle foot orthoses can take the form of both a custom and a non-custom (prefabricated) device. Prefabricated ankle foot orthoses include walking boots, solid and posterior leaf spring AFOs, and articulated AFOs with ankle joints. (a, b) Photos courtesy of Ossur Americas, www.ossur.com; (c) courtesy of Douglas H. Richie, Jr., D.P.M.)
Ankle foot orthoses can take the form of both a custom and non-custom (prefabricated) device. There are prefabricated AFOs gaining popularity for use in a non-ambulatory setting known as night splints. These devices are primarily used to prevent contracture of the gastrocnemius-soleus or the plantar aponeurosis during sleep.
Ambulatory ankle foot orthoses can take the form of both a custom and non-custom (prefabricated) device. Prefabricated ankle foot orthoses include walking boots, solid and posterior leaf spring AFOs, and articulated AFOs with ankle joints (see Fig. 13.5). Custom ankle foot orthoses can also use a solid and posterior leaf spring design, while articulated custom AFOs are generally a more preferred device for the active, athletic patient.
Fig. 13.5
Custom ankle foot orthoses can also use a solid and posterior leaf spring design, while articulated custom AFOs are generally a more preferred device for the active, athletic patient. (The Richie Brace, courtesy of Douglas H. Richie Jr., D.P.M.)
Virtually all ankle braces and AFOs are worn outside the sock of the athlete. In many cases, the sock is vital in providing protection of the integument from friction and pressure of the orthosis. At the same time, compared to athletic taping, the ankle orthosis is usually never in direct contact with the skin which may compromise sensory stimulation and proprioceptive benefits.
Treatment Effects of Ankle Braces and Ankle Foot Orthoses
Studies of Kinetics and Kinematics of Ankle Braces
Most studies of ankle bracing have focused on the kinematic effects, or change in range of motion of the joints of the ankle and hindfoot. In most cases, these investigations have compared various braces, or have compared the results of bracing to athletic taping. Kinetic studies have focused on changes in ground reaction forces as well as displacement of center of pressure.
Kinematic studies have employed various methodologies which explain conflicting outcomes. In scrutinizing these studies, it is important to note if healthy vs. injured subjects were studied. In some cases, subjects were evaluated soon after an ankle sprain, while other studies involved subjects with a history of chronic ankle instability. The majority of studies, however, utilized healthy, non-injured subjects.
When effects on range of motion of the ankle are studied, confusion may arise from the use of terminology. Most kinematic studies of ankle bracing measure effects on “ankle joint” range of motion. The axis of motion of the ankle joint, as originally proposed by Inman [3], is primarily a dorsiflexion/plantarflexion axis allowing almost pure sagittal plane motion. The subtalar joint axis, described by Manter [4], is an inversion/eversion axis, allowing motion primarily in the frontal plane. Thus, when kinematic studies document reduced inversion of the calcaneus, when wearing an ankle brace, the effects of the brace were really at the level of the subtalar joint, rather than the ankle joint. Other studies have measured effects of ankle braces on talar tilt, which is a true measurement of ankle joint inversion/eversion.
Finally, kinematic studies may measure displacement of the ankle during passive movements or during dynamic movements. Studies utilizing passive motion devices vary in terms of position of the ankle in either a plantarflexed or dorsiflexed position. There is mounting evidence that ankle braces affect the ankle differently, depending on the sagittal plane position of the ankle. Dynamic studies simulating real sport movement, such as cutting maneuvers, may be more accurate methodology for assessing effects of ankle bracing.
Early studies of the effects of taping the ankle involved the use of varus stress radiography to measure changes in joint stability. Vaes and Lofvenberg used this technique to demonstrate that tape and a thermoplastic orthosis would be able to significantly reduce talar tilt [5, 6]. However, Vaes showed that the protective effects of taping reduced with exercise [5].
Similar results of taping were demonstrated by Gross [7]. Both taping and an Aircast stirrup significantly limited passive inversion and eversion of the ankle, but this range of motion increased after exercise in the tape group only. Greene and Hillman also compared the results of ankle taping to a semirigid ankle brace [8]. Again, both interventions significantly reduced inversion and eversion of the ankle. After 20 min of exercise, the taping intervention demonstrated a 40% loss of stability, which was not seen in the braced condition. Further studies have validated the finding that tape looses its ability to restrict ankle joint range of motion after as little as 10 min of exercise [9, 10].
Shapiro et al. studied the role of footwear on the effectiveness of taping and bracing the ankle in a cadaveric study [11]. High-top shoes alone and these same shoes combined with taping or bracing significantly improved resistance to ankle inversion compared to the low-top shoe. There was no difference between taping and any of the eight different braces studied.
Ashton-Miller et al. also studied the role of shoe design and found that a three-quarter-top upper allowed an athlete to develop an additional 12% voluntary resistance to inversion moment compared to a low-top shoe [12]. Also, a similar improvement was seen when the subjects wore a lace-up style brace, air-stirrup, or athletic tape. No differences were found among the protective devices.
Vaes et al. used an interesting dynamic measurement technique to determine both the speed and magnitude of talar tilt in a braced and unbraced condition [13]. Patients with functional ankle instability demonstrated significant decreased range and velocity of talar tilt during a simulated sprain when wearing an air-stirrup ankle brace. A slower velocity of inversion was proposed to be an advantage for the athlete, giving more time for muscular activation to prevent a sprain.
Podzielny and Henning also studied restriction of inversion (supination) velocity with four different ankle braces, compared to the unbraced condition [14]. A “supination platform” was used to induce sudden ankle perturbation. Three of the ankle braces reduced overall supination range and supination velocity. No differences were found in plantar pressure distribution patterns.
Further kinetic studies of ankle bracing were conducted by Cordova (Armstrong) [15]. Ankle bracing did not change ground reaction forces during lateral dynamic movement. However, ankle bracing did reduce EMG activity of the peroneus longus during peak impact force.
Siegler et al. were among the first to investigate kinematic changes induced by ankle braces in all rotational directions [16]. Four braces (Ascend, Swede-O, Aircast, and Active Ankle) were studied to determine angular displacement of the segments of the ankle joint complex in three body planes with six degrees of freedom. The authors discovered that significant differences existed among the braces in terms of limitation of inversion–eversion, internal–external rotation, and plantarflexion–dorsiflexion.
Conflicting results of previous studies showing restriction of inversion with ankle bracing were reported by Simpson et al. [17]. Kinematic data were collected from 19 subjects with previous history of ankle sprain during lateral cutting movement. Compared to wearing any of three different ankle braces (AirCast, Malleoloc, or Swede-O), the no-brace condition had a lower amount of ankle inversion. The authors speculated that the subjects may have used injury avoidance behavior in the no-brace condition in order to prevent ankle inversion.
Gudibanda and Wang performed a similar study to Simpson, evaluating ankle position during cutting maneuvers, but using healthy subjects [18]. These investigators found that the ASO lace-up strap reinforced brace did reduce maximum ankle inversion angle by 48% during forward lateral cutting which was significant. However, sideward lateral cutting, decreased inversion angle was only 3% with the brace which was insignificant. Also, the ASO brace decreased ankle plantarflexion angle significantly, by over 40% during both cutting maneuvers. The authors suggested that a reduced ankle plantarflexion angle was advantageous in reducing ankle sprain, citing previous studies by Wright and Neptune who showed that increased ankle plantarflexion resulted in decreased supination torque necessary to cause an ankle sprain [19]. Finally, ankle dorsiflexion was not affected by the ankle brace which the authors concluded would allow normal energy absorbing capacity of the ankle musculature.
Cordova et al. published a meta-analysis of 19 previous published studies comparing three types of ankle support (tape, lace-up, and semirigid) and kinematic changes before and after exercise. It should be noted that only studies of healthy, non-injured subjects were included [20]. The semirigid ankle brace provided the most significant restriction of ankle inversion initially and after exercise. After exercise, the semirigid ankle brace provided an overall decrease of ankle inversion by 23° compared to the control condition. Conversely, the tape and lace-up conditions lost support over time, resulting in an overall restriction of inversion by 12° and 13°, respectively. For ankle joint eversion, the semirigid device was again more effective in reducing motion than either tape or a lace-up brace. Dorsiflexion and plantarflexion range of motion was not affected by the semirigid condition but was most affected by the tape condition compared to the lace-up condition. Taping significantly decreases ankle joint dorsiflexion compared to a lace-up brace and a semirigid brace.
Nishikawa et al. studied shifts of center of pressure and foot pronation–supination angle in 12 healthy subjects in four conditions (semirigid, lace-up, taping, and no brace) [21]. Both the lace-up and taping conditions were associated with greater pronation angle during static stance. During gait, the center of pressure was more laterally displaced with the lace-up and taping condition, increasing the ankle joint moment arm for pronation.
Eils and Rosenbaum studied subjects wearing ten different models of ankle braces during free fall and maximum inversion during a trapdoor ankle perturbation maneuver [22]. Differences in the braces were found in maximum inversion angle which were dependent upon restriction of inversion velocity during free fall.
Spaulding et al. measured kinetic and kinematic variables in ten healthy subjects and ten subjects with chronic ankle instability [23]. Differences were noted in both kinetic and kinematic parameters between the two groups while walking on a level surface, up a step and up a ramp. There were no changes when the subjects wore ankle braces. The authors concluded that ankle braces did not alter selected gait parameters in individuals with chronic ankle instability.
Omori et al. performed a cadaveric study to determine the effects of an air-stirrup ankle brace on the three-dimensional motion and contact pressure distribution of the talocrural joint after lateral ligamentous disruption [24]. After severing of the lateral collateral ankle ligaments, inversion and internal rotation of the talus occurred. Application of the ankle brace only restored inversion displacement, not internal rotation. High pressure developed on the medial surface of the talar dome after ligament sectioning which was not corrected with the ankle brace. The authors concluded that the stirrup ankle brace functions to primarily restrict inversion. They also point out that ankle sprains also have a component of plantar flexion and internal rotation which are not controlled by this type of brace.
The role of footwear and its effect on performance of an ankle brace was studied by Eils et al. [25]. While an air-stirrup, lace-up, and taped condition significantly reduced passive ankle joint motion when worn in a shoe, this support was significantly compromised in the barefoot condition with the air-stirrup only. The authors recommended a lace-up brace for activities which involve a barefoot condition such as gymnastics and dance.
Studies of Ankle Foot Orthoses: Kinetics and Kinematics
Kinetic and Kinematic effects of ankle foot orthoses have been extensively studied [26–30]. However, most of this research has focused on the effects of ankle foot orthoses on patients with neuromuscular conditions. Few reports have been published on the effects of ankle foot orthoses in healthy subjects, and virtually no studies have been conducted on sport applications of these types of devices.
Kitaoka et al. studied the kinetic and kinematic effects of three types of ankle foot orthoses in 20 healthy subjects walking over ground [31]. In the frontal plane, all three orthoses (a solid AFO with footplate, solid AFO with heel portion only, and articulated AFO with footplate) all significantly reduced maximal hindfoot inversion, but did not affect eversion. The solid ankle AFO design significantly reduced both plantarflexion and dorsiflexion of the ankle, while the articulated ankle AFO did not affect ankle sagittal plane motion compared to the unbraced condition. Midfoot motion was reduced with the articulated AFO, and increased with the solid AFO. Cadence was reduced with the solid AFOs. All three braces were associated with decreased aft and medial shear forces compared to the non-braced condition.
Radtka et al. studied the kinetic and kinematic effects of solid and hinged (articulated) ankle foot orthoses on 19 healthy subjects during stair locomotion [32]. A unilateral hinged ankle foot orthosis produced kinematic and kinetic effects which were similar to subjects wearing no orthosis. The unilateral solid ankle foot orthosis produced more abnormal ankle joint angles, moments, and powers and more proximal compensations at the knee, hip, and pelvis than the hinged AFO during stair locomotion. Subjects wearing either orthosis walked slower during stair locomotion compared to the non-braced condition.
Hartsell and Spaulding measured passive resistive torque applied throughout inversion range of motion of the ankle in healthy subjects and those with chronically unstable ankles [33]. A hinged semirigid non-custom ankle foot demonstrated significant increased passive resistive inversion torque forces and restricted overall inversion motion better than a lace-up ankle brace.
In summary, the kinetic and kinematic effects of ankle bracing have been well studied with consistent results in several areas. Most ankle braces and ankle foot orthoses have been demonstrated to have an ability to restrict ankle joint inversion. Some braces affect ankle joint eversion, and little data is available to determine the effects of bracing the ankle in the transverse plane. In the sagittal plane, significant restriction of range of motion of the ankle joint and the midfoot can be accomplished, depending on the design of the brace, or use of simple taping.
What remains obscure is an understanding of the optimal range and plane of motion controlled by an ankle orthosis to achieve a desired treatment effect. There are clear indications that restriction of motion of any joint in the lower extremity will have negative effects in the neighboring joints, both proximal and distal. Of concern for the athlete is the effect of bracing on overall lower extremity function and sports performance.
Effects of Ankle Bracing on Sports Performance
Many forms of sport combine elements of running, jumping, and side-to-side movements. Speed and power of these movements are dependent upon an intact lower extremity which has efficient muscle firing and transfer of moment to the various joints for motion, and subsequent displacement of the body to an intended direction. The range of motion and alignment of the joints of the foot and ankle are critical to the efficient movement of the entire body. Limitation of motion of any joint of the hindfoot complex could be an advantage if excessive motion were available. Conversely, limitation of motion could potentially have negative consequences if a joint is restricted to a less than optimal range.
Thus, many studies have been undertaken to determine the effects of bracing and taping on overall athletic performance. As seen in kinematic studies, performance studies of ankle bracing lack consistency in methodology and have given conflicting results.
One of the first studies of performance and ankle bracing was conducted by Burks et al. [34]. Thirty healthy collegiate athletes performed four performance events: the broad jump, vertical leap, 10 yard shuttle run, and a 40 yard sprint. The tests were performed with both ankles taped, or with both ankles wearing two types of lace-up braces. The results were compared to the no-tape, no-brace condition. Half of the subjects perceived that at least one device decreased their performance. All three conditions significantly reduced vertical jump. Shuttle run was not affected by the braces, but was slowed by the taping. Broad jump was affected by only one of the lace-up braces, not by taping. Sprinting was affected by taping and one of the braces.
A different type of subject pool was utilized to study performance and bracing in a study by Hals et al. [35]. Twenty-five subjects who had recent acute ankle sprain but who had mechanically stable ankles with residual symptoms of functional instability were studied. Performance tests included a shuttle run and a vertical jump, with and without an Aircast stirrup brace. Use of the semirigid ankle support significantly improved shuttle run time, but not vertical jump performance.
Jerosch and Schoppe also studied subjects with functional ankle instability to determine the effects of a flexible strap style ankle brace on dynamic movements [36]. In a side step running test, the ankle support produced a significant faster time than the unbraced condition. In addition, the authors found no negative effect after 3 months of brace use in terms of isokinetic strength as well as speed of side step running.
Cordova et al. performed a meta-analysis of 17 randomized controlled trials which used a cross-over design to measure effects of bracing on performance measures [37]. The studies included comparison of tape, semirigid, and lace-up braces. Of these studies, approximately 30% used injured subjects. In terms of sprint speed, the largest effect was found with a lace-up brace, which yielded a 1% impairment. For agility speed, the net effects of all three supports was negative, but only 0.5%. For vertical jump, a 1% decrease in performance was found in all three conditions. The authors concluded that these negative effects are trivial for most individuals, but may have greater significance for elite athletes. They also recommended that the benefit of external ankle support in preventing injury outweighs the small negative effects on sports performance.
Balance and Proprioception
Athletes with functional instability of the ankle have been demonstrated to have deficits in balance and proprioception [38–41]. Restoration of proprioception has resulted in reduced frequency of ankle sprain [42]. Research has shown that lower extremity orthoses can have a positive effect on balance and proprioception.
Functional ankle instability consistently causes deficits in postural control [43–45]. Studies of foot orthoses have shown positive effects in improving postural control in both injured and non-injured subjects [46–53]. Mechanisms by which foot orthoses can improve postural control include optimizing foot position, reducing strain and load on supportive soft tissue structures, and improving the receptor sensory field on the plantar surface of the foot [54].
Neuromuscular control of the ankle relies on afferent input to the central nervous system. In the lower extremity, the somatosensory system provides this afferent input. This system includes the mechanoreceptors in the ligaments of the ankle, the cutaneous receptors in the feet and lower legs and the stretch receptors located in the muscles and tendons around the ankle.
Peroneal reaction time and postural sway are examples of an intricate reflex which includes sensory input (proprioception) and motor output. Since the output side of the reflex has multiple variables such as muscle activation time and muscle strength, looking at a performance task such as peroneal reaction time or postural sway does not actually isolate true proprioception. Measuring true proprioception is theoretically impossible, but measuring certain aspects of proprioception can give valuable information.
Studies of certain aspects of proprioception with taping or bracing subjects with previous history of ankle sprain have focused on either passive movement detection or joint position sense. Feuerbach et al. determined that the afferent feedback from skin and muscle around the ankle joint was more important than ligament mechanoreceptors in providing proprioceptive feedback [55]. Their studies on healthy subjects showed that a stirrup ankle brace significantly improved accuracy of ankle positioning tasks performed off weight bearing. Some studies have shown improvements of ankle joint position sense when ankle braces are worn [56, 57]. Other studies have reported no change or worsening of proprioception with taping and bracing [58, 59].
Raymond et al. conducted a systematic review of the literature and found eight high quality studies using controlled, cross-over design to measure either passive movement detection of joint position sense in subjects with and without taping of functionally unstable ankles [60]. Meta-analysis of the pooled results showed no improvements of proprioception when subjects with previous ankle sprain or functional instability were taped or braced. The authors concluded that while evidence exists for the protective benefit of bracing and taping the ankle, the reduction of risk of sprain is not likely due to enhanced proprioception.
Chronic ankle instability has been associated with delayed peroneal reaction time, which relies on proprioception as well as motor neuron activation [61, 62]. Karlsson showed that athletes with unstable ankles had significant delayed peroneal reaction time when tested on trap doors which could simulate inversion ankle sprains [63]. When the subjects were taped around the ankles, peroneal reaction time significantly improved.
Improvements of the peroneal stretch reflex with ankle bracing were verified in other studies of healthy subjects [64, 65]. However, another study by Shima et al. showed that ankle taping and bracing would delay the peroneal reflex in both normal and hypermobile ankles [66]. They speculated that the effects of external support would limit ankle inversion, and thus delay the peroneal stretch reflex.
Postural control is the ability of an individual to keep their center of mass within the borders of their base of support. It is a mechanism to maintain upright balance. The effects of ankle braces on postural control has been extensively studied. Baier and Hopf studied 22 athletes with functional instability of the ankle joint compared to 22 healthy athletes [67]. A significant improvement of postural control, as evidenced by reduced mediolateral sway velocity was found in the instability group when wearing both a rigid and semirigid stirrup ankle brace. However, other studies, performed on both healthy subjects and on subjects with functional ankle instability have failed to show any improvements of postural control with the use of ankle braces [68–71].
Studies of effects of ankle foot orthoses on balance have been performed on neurologically impaired subjects, and have not been performed on athletes [72, 73]. Cattaneo et al. showed that AFOs would improve static balance in patients with multiple sclerosis, but would compromise dynamic balance during gait [73].
In summary, studies of effects of ankle orthoses on balance and proprioception do not provide consistent findings. Yet, studies of treatment effects of these devices commonly conclude that any positive findings must be attributed to improvements in proprioception. In the final section of this chapter, several studies show the protective benefit of preventing the incidence of ankle sprains in subjects wearing ankle braces. While the incidence of sprains was clearly reduced, the severity of the sprain was not affected. Thus, a mechanical restraint of ankle rotation did not occur, whereas a proprioceptive influence possibly prevented the event itself.
As with previous studies, investigations of proprioceptive effects show varied results because of the various types of subjects ( injured vs. non-injured, vs. symptomatic) and the methodology employed (static stabiliometry vs. dynamic posturography). Furthermore, ankle orthoses have not demonstrated the consistent improvements in postural control which have been previously demonstrated with foot orthoses in healthy subjects and subjects with chronic ankle instability. Further research is needed to determine the role of support of both the foot and the ankle in the treatment of athletes with chronic ankle instability.
Treatment of Injury
Ankle braces and ankle foot orthoses are commonly used in the treatment of injuries of the leg, ankle, and foot. There is no uniform consensus about the timing, selection, and criteria for use of ankle braces or ankle foot orthoses in the management of lower extremity injury.
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