Understanding and Treating Lateral Ankle Sprains ...

Understanding and Treating Lateral Ankle Sprains and their Consequences

Erik A. Wikstrom, Tricia HubbardTurner & Patrick O. McKeon

Sports Medicine ISSN 0112-1642 Volume 43 Number 6 Sports Med (2013) 43:385-393 DOI 10.1007/s40279-013-0043-z

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Author's personal copy Sports Med (2013) 43:385–393 DOI 10.1007/s40279-013-0043-z

LEADING ARTICLE

Understanding and Treating Lateral Ankle Sprains and their Consequences A Constraints-Based Approach Erik A. Wikstrom • Tricia Hubbard-Turner Patrick O. McKeon

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Published online: 12 April 2013 Ó Springer International Publishing Switzerland 2013

Abstract Lateral ankle sprains are a common consequence of physical activity. If not managed appropriately, a cascade of negative alterations to both the joint structure and a person’s movement patterns continue to stress the injured ligaments. These alterations result in an individual entering a continuum of disability as evidenced by the *30 % of ankle sprains that develop into chronic ankle instability (CAI) and up to 78 % of CAI cases that develop into post-traumatic ankle osteoarthritis (OA). Despite this knowledge, no significant improvements in treatment efficacy have been made using traditional treatment paradigms. Therefore, the purpose of this review is to (1) provide an overview of the consequences associated with acute lateral ankle sprains, CAI and post-traumatic ankle OA; (2) introduce the patient-, clinician-, laboratory (PCL)-oriented) model that addresses the lateral ankle sprains and their consequences from a constraints perspective; and (3) introduce the dynamic systems theory as the framework to illustrate how multiple post-injury adaptations create a singular pathology that predisposes individuals with lateral ankle sprains to fall into a continuum of disability. The consequences associated with lateral ankle sprains, CAI and ankle OA are similar and encompass alterations to the structure of the ankle joint (e.g. ligament laxity, positional faults, etc.) and the sensorimotor function responsible for proper ankle joint function (e.g. postural control, gait, etc.). Further, the impairments have been quantified across a range of patient-oriented (e.g. self-

E. A. Wikstrom (&) T. Hubbard-Turner Department of Kinesiology, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 2822, USA e-mail: [email protected] P. O. McKeon University of Kentucky, Lexington, KY, USA

report questionnaires), clinician-oriented (e.g. bedside measures of range of motion and postural control), and laboratory-oriented (e.g. arthrometry, gait analysis) outcome measures. The interaction of PCL-oriented outcomes is critically important for understanding the phenomenon of CAI across the continuum of disability. Through the integration of all three sources of evidence, we can clearly see that an ankle sprain is more than just a peripheral musculoskeletal pathology with only local consequences. The dynamic systems theory illustrates that the organization of human movement/function is shaped by the interaction of (1) organismic constraints (health of the person); (2) task constraints; and (3) environmental constraints. However, ankle sprains increase the organismic constraints (i.e. changes in joint structure and sensorimotor function) that significantly hinder an individual’s function and may be the underlying cause for the continuum of disability associated with CAI. To treat and/or prevent an individual from entering the continuum of disability, greater protection of the ankle ligaments is needed immediately after injury. Subsequent rehabilitation should then focus on goal-oriented rehabilitation (i.e. quality of the movement pattern) rather that task-oriented rehabilitation (i.e. do these exercises). When evaluating patients with ankle inversion trauma and/or instability, it is imperative to remember that an ankle sprain is not simply a local joint injury; it can result in a constrained sensorimotor system that leads to a continuum of disability and life-long consequences such as high injury recurrence and decreased quality of life if not managed properly.

1 Introduction During interscholastic and intercollegiate sports in the US, *60 % of all injuries are lateral ankle sprains (LAS) [1, 2].

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However, the true incidence of LAS may be much greater because *55 % of people do not seek treatment from a healthcare professional for LAS [3]. Damage to the lateral ligaments and other structures (e.g. subchondral bone, subtalar ligaments, etc.) can lead to the development of an unstable ankle joint (i.e. hypo or hypermobile). Hypo- or hypermobility of the ankle can lead individuals to develop compensatory movement patterns in an effort to maintain proper function [4] but are also hypothesized to cause further strain on the injured structures and alter the axis of ankle joint rotation. Thus, a continuum of disability [5, 6] (Fig. 1) is started when proper healing and joint alignment are not restored [7]. Evidence of this continuum is the *30 % of those who suffer a first time LAS that develop chronic ankle instability (CAI) [8–10]; defined as recurrent episodes of lateral instability resulting in multiple ankle sprains [11]. However, this percentage has been reported to be as high as 75 % [8]. Further, a link has been established between CAI and post-traumatic ankle osteoarthritis (OA), with 68–78 % of CAI patients developing ankle OA [12–14]. The development of ankle OA after an LAS is thought to occur via two mechanisms: (1) an acute osteochondral lesion suffered concurrently with an ankle sprain [15]; and/ or (2) a chronic change in ankle joint structure and mechanics that lead to repetitive cartilage degeneration [16]. Residual symptoms associated with CAI also alters an individual’s function and has been shown to impact participation in sporting/physical activities [17]. The potential for CAI to decrease physical activity suggests a significant role in negatively affecting public health as physical inactivity is a leading risk factor for mortality [18]. Despite

Musculoskeletal injury

Decreased functional performance

Continuum of disability

Increased organismic constraints

Poor sensorimotor control

Fig. 1 Theorized continuum of disability that impacts those with acute lateral ankle sprains, chronic ankle instability, and posttraumatic ankle osteoarthritis (modified from McKeon [84], with permission from SLACK Incorporated)

the potential public health problem that CAI represents, no significant inroads have been made at preventing the condition or permanently treating the associated sequelae using traditional treatment paradigms. This article will therefore provide an overview of the consequences associated with LAS, CAI, and post-traumatic ankle OA. Then, we will introduce a novel recognition and treatment paradigm for LAS and its consequences. This paradigm, the patient-, clinician-, laboratory (PCL)-oriented model, addresses the LAS and their consequences from a constraints perspective [19]. Finally, the dynamic systems theory [20] will be introduced to provide the framework that will help illustrate how multiple post-injury adaptations (i.e. constraints) create a singular pathology that predisposes individuals with LAS to fall into a continuum of disability [5, 6] that impacts the patient’s and public health.

2 Patient-, Clinician, and Laboratory (PCL)-Oriented Alterations 2.1 Alterations in Acute Lateral Ankle Sprains Acute LAS are painful and debilitating injuries [21, 22] with a wide range of consequences. Patient-oriented evidence illustrates that self-assessed disability, measured via questionnaires, is significantly increased for 3-weeks post injury in mild and moderate ankle sprains [22]. Further, *20 % of LAS patients feel that their ankle is unstable a full year after an initial injury [23]. These deficits may relate to deficits/alterations reported in clinician-oriented outcomes including: range of motion (ROM) [24, 25], posterior talar glide [26], distal fibula position relative to the tibia [27], and lateral ligament laxity (Table 1). Laboratory-oriented evidence indicates that joint position sense [28], isometric strength in multiple planes of motion [29, 30], postural control on the involved limb [31, 32] and uninvolved limb [33], as well as temporal and spatial parameters of gait [34] are all impaired following acute LAS. 2.2 Alterations in Those with Chronic Ankle Instability While the exact pathoaetiology of CAI remains unknown, theoretical models of CAI suggests that it is multifactorial in nature [11, 35, 36]. Therefore, while lateral ligamentous laxity may appear to be the most obvious adaptation of LAS, it is unlikely that laxity itself is the sole cause of CAI. Rather, the true mechanism is most likely linked to a number of initial adaptations that cause a cascade of events that ultimately leads to CAI (Fig. 2) [35]. This is evidenced

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Table 1 Summary of hypermobility evidence after lateral ankle sprains Assessment methods

Percentage with hypermobility

Time postinjury

Anterior drawer [92]

30 %

2 weeks


11 %

6 weeks

Anterior drawer [93] Athrometry [94]

12 % [Anterior displacement and inversion rotation relative to an uninjured control group

8 weeks 8 weeks

Talar tilt via stress radiography [95]

42 % and 33 % from separate treatment groups

12 weeks

Stress radiography [96]

5%

12 weeks


*30 %

1 year

Stress radiography [97]

50 %

9–13 years

by the fact that not all CAI patients will present with all of the deficits discussed in this section. The most commonly reported symptom associated with CAI is decreased functional performance due to repeated episodes of ‘giving way’ [11, 35]. A number of selfassessed disability scales (e.g. Foot and Ankle Ability Measure [FAAM]) have been used to quantify patientoriented evidence in those with CAI [37]. The current recommendations for classifying those with CAI based on self-assessed disability is a self-reported loss of C10 % of function during activities of daily living and C20 % loss of function during sport-related activities [38]. Clinician-oriented evidence includes: increased laxity [39–43], anterior positional faults of the distal fibula [44] and talus [45], decreased dorsiflexion ROM [46], and static [47] and dynamic balance deficits [35, 48–50]. Laboratory-oriented

evidence has also demonstrated a wide range of alterations in those with CAI (see Hertel [35] for further review). These impairments have included local effects thought to be a direct consequence of the joint damage (e.g. alterations in joint position sense) but also global deficits in sensorimotor function (e.g. alterations in proximal muscle and joint control) indicating that both spinal and supraspinal levels of motor control [43, 51–58]. Unfortunately, the link between local and global impairments is poorly understood at this time. 2.3 Alterations in Those with Post-traumatic Ankle Osteoarthritis Those with post-traumatic ankle OA have significant amounts of self-assessed disability (i.e. patient-oriented evidence) regardless of the scale used [59–66]. Clinicianoriented impairments includes muscle atrophy [63], impaired ankle muscle strength [59], and increased mechanical stiffness [59]. Laboratory-oriented evidence indicates that static postural control [59, 62, 66], spatiotemporal gait parameters [60, 61, 64, 65], muscle activation patterns [65], lower leg strength [63, 65], calf muscle atrophy [67], and centrally mediated motor control mechanisms [66] are all altered in those with ankle OA. The similar impairments (i.e. constraints) across the three conditions, which all directly or indirectly impact joint moments and loading, support the hypothesis that the development of ankle OA from CAI is likely the result of cartilage degeneration due to acute defects [15] and/or prolonged adaptations in the structure and mechanics of the ankle joint [16].

3 The PCL Model Lateral ankle sprain causes Ligament damage

Impaired sensory pathways to the CNS

Initial consequences then lead to: Structural alterations

Inhibition of appropriate spinal reflexes

Ultimately, chronic ankle instability is developed and characterized by: Altered joint loads

Alterations in normal movement patterns

Altered joint loads typically result in post-traumatic ankle osteoarthrithis

Fig. 2 Hypothetical cascade of events that causes the development of CAI and post-traumatic ankle OA (modified from McKeon et al. [6], with permission)

The interaction of PCL-oriented outcomes is important for understanding the phenomenon of CAI across the continuum of disability. It is crucially important to assess how organismic constraints measured with clinician- and laboratory-oriented outcomes, manifests into patient-reported limitations and restrictions. Gaining the patient’s perception of disability will also help assess treatment effectiveness on function and quality of life. Those with acute LAS, CAI and post-traumatic ankle OA demonstrate significant and similar constraints in PCL-oriented outcome measures. Cumulatively, these three sources of evidence indicate that an ankle sprain is more than just a peripheral musculoskeletal pathology. The interaction of these three sources of evidence can also help identify effective evidence-based treatments that can address both the local constraints and global disability.



4 The Dynamic Systems Theory Framework The dynamic systems theory [68] provides a framework for explaining how the sensorimotor system develops strategies to accomplish movement goals. Within this theory, the human body is a system composed of many interacting parts (degrees of freedom) that can be organized in a variety of ways to accomplish movement goals [69]. The hallmark of this system is its ability to adapt to changing demands both internally and externally. A healthy sensorimotor system can accomplish a movement goal in a variety of ways based on its interactions with the task performed and the environmental cues received [20]. Therefore, the organization of the sensorimotor system is constrained/shaped by the interaction of the (1) health of the person (organismic constraint); (2) task being performed (task constraint); and (3) environment in which a movement goal is executed (environmental constraint) [20, 70] (Fig. 3). The ability of the sensorimotor system to spontaneously reorganize movement strategies translates to an ability to successfully cope with changing task and environmental constraints to accomplish movement goals; in other words, functional variability [71]. However, too much or too little variability will impair an individual’s ability to cope with changing demands (see Stergiou et al. [72] for further review). Ankle injuries increase the organismic constraints (i.e. the clinician and laboratory adaptations listed in Sect. 2.1–2.3) acting on the sensorimotor system and significantly hindering the sensorimotor system’s ability to accomplish movement goals [11, 20]. Consequently, injured parts (e.g. articular receptors) of the system cannot be used in movement solution development, thus altering functional variability after an LAS and in those with CAI. However, those with CAI appear to demonstrate less variability in global

measures of postural control [73] but increased variability in local joint coupling during gait [74]. Thus, functional variability within the continuum of disability is contextually dependent in those with CAI. Epidemiological evidence supports this framework in that the primary risk factor for an ankle sprain is a previous history of one [75]. Based on these converging arguments, reduced functional variability may be the underlying cause for the continuum of disability (Fig. 1) associated with CAI [5]. That is, increased sensorimotor constraints predispose a person to injury and injury increases the constraints on sensorimotor control.

5 Application of the PCL Model to Treatment Strategies With the high percentage of re-injury occurrence [76] and development of CAI [77] research needs to examine shortand long-term outcomes from a constraints perspective to understand the effectiveness of therapeutic interventions. Ideally, this research examines not only specific mechanical and/or sensorimotor constraints but the interactions among them. Numerous investigations have assessed the efficacy of rehabilitation techniques on short-term outcomes (e.g. pain, ROM). Based on this evidence, the current standard of care for acute LAS management involves rest, ice, compression, elevation (RICE) and functional rehabilitation (i.e. early mobilization with support) [78]. In more severe cases, LAS are treated with crutches and are typically immobilized for a short period of time [78]. However, there is little empirical evidence examining the interactions of different kinds of constraints after an LAS, which may be one of the reasons for the development of CAI. 5.1 Limiting the Introduction of Organismic Constraints

Organism

Sensorimotor control Task

Environment

Fig. 3 Sensorimotor organization based on the interaction of organismic, task, and environmental constraints as described by the Dynamic Systems Theory

After an acute LAS, at least, the lateral ligaments of ankle have been damaged (see Sect. 6.0 for information regarding additional structures). To promote healing of all structures, the joint needs to be protected [79]. Previous research has traditionally advocated early movement of the ankle; however, too much early activity may not allow adequate time for ligament healing. Maximizing ligament healing will help to minimize the development of, or at least the magnitude of, additional constraints believed to lead to the development of CAI. During the inflammatory phase of healing, protecting the joint to best approximate ligament tissue and promote fibroblastic repair is of the utmost importance. To do this, it is recommended that immobilization and/or external support techniques be worn through the inflammatory and


repair phases of healing (*3-weeks post-injury depending on injury severity). Results of recent randomized clinical trials, seem to support this notion [80, 81]. In less severe sprains (grades I and II) an Air-Stirrup brace combined with an elastic wrap appears to best restore function. These types of brace minimize motion at the ankle that should facilitate tissue approximation and therefore healing. An elastic or tubular wrap alone are not recommended, even for minor grade I sprains, because research suggests that they do not provide adequate protection to allow restoration of function relative to other available options [80, 81]. In more severe cases (grade III) preliminary evidence suggests that a below-knee cast may best enable return to normal function [80, 81]. Based on the current literature, immediate care of LAS should encourage protection of the ankle through rigid immobilization and/or external support (AirStirrup brace with elastic wrap, below the knee cast). 5.2 Overcoming Organismic Constraints via Functional Variability In rehabilitation, the elimination of residual pain (no treatment consensus exists) and restoration of arthrokinematic and ROM constraints (see Wikstrom and McKeon [82] for further review) are needed before sensorimotor retraining begins. During sensorimotor retraining, it becomes imperative that the clinician is very specific when identifying the desired movement goal for the patient [83]. Rather than focusing on the task to be performed, the functional activities should be associated with the quality of the movement goal execution (i.e. improving functional variability) [72]. The most important elements for the development of functional variability are to incorporate: (1) a systematic progression through the exercises; (2) a logical manipulation of task and environmental constraints at each level of the progression; (3) specific outcomes that capture improvements and help determine when patients should progress; (4) an ability to reduce the outcomes into a decision as to whether the patient has overcome the continuum of disability; and (5) an assurance that the process is replicable by documenting the systematic, logical, empirical, and reductive elements [84]. For complete definitions of these elements, see Table 2. 5.3 Task Constraints in Rehabilitation Changing the demands of the task results in changes within the sensorimotor system to accomplish the movement goal [83]. The complexity of the task will govern the variability of movement solutions the sensorimotor system can use. When progressing an individual through a rehabilitation programme, it becomes essential for the movement goals to be meaningful to the individual [83]. The task constraints

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can then be structured to challenge the sensorimotor system as it spontaneously organizes (i.e. develops new solutions) to accomplish the movement goal. Progressing an individual through continually more complex tasks while tracking errors in movement goal execution provides the systematic and logical framework for challenging the sensorimotor system [5, 6, 83, 85]. Specific examples of a validated constraints-led progression can be found in two previously published investigations [85, 86]. 5.4 Environmental Constraints in Rehabilitation Environmental constraints (or cues) are essential components for the organization of the sensorimotor system [83]. Cues from the environment should be considered for the predictability they offer to the sensorimotor system [83], as more predictable cues allow greater flexibility in the development of successful movement goal strategies. Consequently, a valuable rehabilitation activity has a systematic progression from predictable to more unpredictable environmental cues [5, 6, 83, 85]. It is important to note that in a constraint-based rehabilitation programme, patients progress based on their individual ability to accomplish the movement goals error free and not on a specific number of sets or repetitions. It is also important to note that with the systematic and logical progression of task and environmental constraints, patient’s progress through rehabilitation at their own rate based on their individual ability to accomplish the movement goals error free. Upon completion of the error-based balance training programme developed by McKeon et al. [85], patients reported significant improvements in their ability to engage other task and environmental constraints in activities such as running, cutting and participating in their desired activities [85]. The goal of balance training and functional rehabilitation from the dynamic systems perspective is to restore the sensorimotor system’s ability to cope with change during the execution of movement goals, thus improving sensorimotor control and functional performance. Once a movement/rehabilitation goal can be accomplished without error, the constraints can again be systematically increased. In order to accomplish more advanced movement goals effectively, more degrees of freedom (i.e. using more joints, muscles, etc.) are necessary to correct for errors introduced during goal execution. By incorporating more degrees of freedom to correct errors, the Continuum of Disability (Fig. 1) can be broken. Clinicians can utilize the principles of the purposeful manipulation of task and environmental constraints to guide the progression of rehabilitation. By doing so, it is possible to tailor a programme to a patient’s ability to achieve movement goals and restore sensorimotor system function.



Table 2 Elements of a constraints-led rehabilitation programmea Elements of programme

Definition

Systematic

The programme works through a sequence of activities meant to build on one another. Regardless of the level the patient enters the programme; the progression sequence is governed by the error-based system

Logical

The task and environmental constraints manipulation provides challenges to the sensorimotor system in its development of new solutions to accomplish movement goals. The progression of constraints manipulation follows a progression in which the clinician can see that the patient has increased the capacity to take on greater task and environmental demands

Empirical

The PCL-oriented measures used to track the progress of changes in response to the rehabilitation programme. The measures chosen should be based on those that have been found to be sensitive to detecting deficits in those with CAI as well as detecting improvements in functional performance within the scope of the PCL model

Reductive

Based on the changes of the empirical measures combined with the logical manipulation of task and environmental constraints, the clinician is able to determine whether the rehabilitation programme was effective

Replicable

Thorough documentation of the systematic, logical, empirical and reductive elements of the programme allow clinicians to track outcomes across patients and share their findings with other colleagues through case studies, case series and higher level clinical trials. The ability to reproduce similar clinically meaningful improvements across a variety of patients is the hallmark of a successful rehabilitation programme. This should be tracked and shared in your profession

a

Components of the programme are derived from the elements of research [85]

CAI chronic ankle instability, PCL patient-, clinician-, laboratory-oriented

To date, a constraints-based balance training programme has been used in different laboratories and has consistently found significant improvements in self-assessed disability and postural control [85–87]. Lastly, outcome tools that capture PCL-oriented changes within the sensorimotor system are needed. For example, three independent investigations [85–87], have demonstrated significant improvements in self-reported function (patient-oriented evidence), dynamic reach distance (clinician-oriented balance outcome), and spatiotemporal postural control (laboratory-oriented evidence) in those with CAI after completing a constraints-based balance training programme. By assessing outcomes in all aspects of the PCL model, it is possible to determine if a rehabilitation programme has an impact on taking a patient out of the Continuum of Disability.

acute LAS and post-traumatic ankle OA. Thus, we are left to speculate that restoring functional variability after acute LAS would prevent the development of CAI; however, further research is needed to test this hypothesis. Further, longitudinal investigations are needed to determine if restoring functional variability also restores ‘normal’ joint loading and subsequently slows ankle OA progression. Finally, this article has focused only on post-traumatic ankle OA that results from CAI but this represents a small percentage (16 %) of those with any kind of ankle OA [91]. Fractures (e.g. plafond, talar, malleolar, etc.) also disrupt joint loads and mechanics and eventually lead to cartilage degeneration [91].

6 Limitations

When evaluating patients with ankle inversion trauma and/ or instability, clinicians should consider the Continuum of Disability rather than simply local instability. We recommend using the constraints-led approach to guide decisions about comprehensive sensorimotor system evaluation, the development of rehabilitation progressions and safe return to participation. Most importantly, an ankle sprain is not simply a local joint injury; it results in a constrained sensorimotor system that leads to a continuum of disability and life-long consequences such as high injury recurrence and decreased quality of life.

The current article focused on damage to the lateral ligaments of the ankle and how to treat such damage. However, LAS can result in trauma to additional structures such as the distal tibiofibular joint, subtalar joint, peroneal muscle group and the talar articular surface [88, 89]. Further, the incidence of subtalar instability is estimated to be *75 % in individuals with CAI [90]. The complexity of the initial injury may dictate the pattern of constraints developed and subsequent functional loss but this is speculative as research has yet to empirically validate this hypothesis. Another limitation within the literature is the lack of constraint-based rehabilitation evidence in patients with

7 Conclusions

Acknowledgments No funding was provided for the preparation of this paper and none of the authors have had a real or perceived conflict of interest to report.


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