Athletic Training and Sports Health Care

Original Research 

Physiotherapists’ Understanding of Functional and Mechanical Insufficiencies Contributing to Chronic Ankle Instability

Fearghal Kerin, BSc; Eamonn Delahunt, PhD, BSc

Abstract

Ankle joint sprain and the subsequent development of chronic ankle instability (CAI) are commonly encountered by clinicians involved in the treatment and rehabilitation of musculoskeletal injuries. The development of CAI is dependent on the complex interaction of numerous mechanical and functional insufficiencies and deficits, which practicing physiotherapists must be able to identify and treat. In this study, 281 surveys were administered to members of the Irish Society of Chartered Physiotherapists (ISCP) to determine physiotherapists’ knowledge of CAI, functional instability (FI), mechanical instability (MI), and preferred treatment techniques. Of the 150 respondents, 71% had a good understanding of CAI. Approximately 73% and 71% displayed comprehension of FI and MI respectively. We concluded that physiotherapists’ knowledge of the insufficiencies contributing to the development of these entities was poor. Respondents used strengthening programs and joint mobilizations during rehabilitation; single leg balance, hopping, and wobble board training were the most commonly used balance retraining methods.

Abstract

Ankle joint sprain and the subsequent development of chronic ankle instability (CAI) are commonly encountered by clinicians involved in the treatment and rehabilitation of musculoskeletal injuries. The development of CAI is dependent on the complex interaction of numerous mechanical and functional insufficiencies and deficits, which practicing physiotherapists must be able to identify and treat. In this study, 281 surveys were administered to members of the Irish Society of Chartered Physiotherapists (ISCP) to determine physiotherapists’ knowledge of CAI, functional instability (FI), mechanical instability (MI), and preferred treatment techniques. Of the 150 respondents, 71% had a good understanding of CAI. Approximately 73% and 71% displayed comprehension of FI and MI respectively. We concluded that physiotherapists’ knowledge of the insufficiencies contributing to the development of these entities was poor. Respondents used strengthening programs and joint mobilizations during rehabilitation; single leg balance, hopping, and wobble board training were the most commonly used balance retraining methods.

The authors are from the University College Dublin, Dublin, Ireland.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Eamonn Delahunt, PhD, BSc, School of Public Health, Physiotherapy and Population Science, University College Dublin, Belfield, Dublin 4, Ireland; e-mail: eamonn.delahunt@ucd.ie.

Received: July 20, 2010
Accepted: September 13, 2010
Posted Online: October 29, 2010

Despite continuing advances in prevention and treatment, the ankle remains the second most frequently injured joint among sports participants.1 In addition, sprain of the lateral ankle joint ligaments is the most common acute sports trauma, accounting for 14% of all sports injuries.2 The mechanism of injury for a lateral ankle joint sprain typically involves excessive movement or rotation of the ankle.3 It has been suggested that most ankle sprains occur during systematic loading and unloading, as the ankle joint is considered to be a stable structure when fully loaded due to the high congruity of the articular restraints.4 The anterior talofibular ligament is most often injured when the foot is in a plantar flexed position; when the foot is dorsiflexed, the calcaneofibular ligament is most often injured.

The most important predisposing factor to lateral ankle sprain is a history of previous sprain.5 Following initial ankle joint sprain, re-injury rates have been shown to be as high as 80%.6 Braun7 suggested that 70% of athletes experience residual symptoms 18 months post-injury. In an analysis of 563 participants following an initial ankle joint sprain, Yeung et al8 reported that the following residual symptoms were the most prevalent: pain (30.2%), instability (20.4%), crepitus (18.3%), weakness (16.5%), stiffness (14.6%), and swelling (13.9%). The presence of these residual symptoms and repeated inversion injury has been defined as chronic ankle instability (CAI).5 It is now accepted that anatomic laxity is not the only causal factor for the development of repeated ankle sprain9–11 and the subsequent development of CAI. Chronic ankle instability is considered to develop as a result of the complex interaction of numerous mechanical and functional insufficiencies.5

Mechanical instability is the result of pathological laxity secondary to aberrant restraining capabilities of the ankle joint supporting ligaments. Functional instability refers to the presence of repeated ankle joint inversion injury and recurrent episodes of giving way and ankle sprain.11 Various mechanical and functional insufficiencies have been proposed to contribute to the development of CAI. Mechanical instability includes deficits in arthrokinematics, pathologic laxity, synovial changes, and degenerative changes.5 Functional instability includes deficits in strength, proprioception, neuromuscular, and postural control.5

If physiotherapists, in their role in managing CAI, are to adhere to the principals of evidence-based practice, it is important that they are fully aware of the insufficiencies that contribute to the development of CAI. It is hypothesized that clinicians are currently unaware of the best practice and therefore, are unable to manage CAI in the most efficacious manner. Thus, the aim of this study was to conduct a cross-sectional analysis of physiotherapists who treat CAI and ascertain their knowledge and practice patterns relating to this condition.

Methods

Participants

Ethical exemption for the study was received from the College of Life Sciences Human Research Ethics Committee due to the anonymous nature of the questionnaire. A postal survey was conducted among a sample of practicing physiotherapists in Ireland.

An application was submitted to the Chartered Physiotherapists in Sports and Exercise Medicine (CPSEM) clinical interest group of the Irish Society of Chartered Physiotherapists (ISCP) to solicit participants. Following the standard protocol for research applications, postal addresses for members of this group were received. Contact was made with the outpatient physiotherapy departments in 4 major hospitals, and consent was received to send the questionnaire to members of staff treating patients with CAI; each was sent 4 questionnaires. There were 10 staff members who agreed to complete the questionnaire, and permission was received to distribute 10 questionnaires to a group undergoing postgraduate education. Fifty physiotherapists from private practices were chosen at random from the ISCP database, in addition to 65 from the CPSEM. Selected physiotherapists were given an invitation letter with an explanation of the aims of the study, a letter of introduction from the research team, the survey instrument, and a stamped addressed envelope for returning the survey to the principal investigator.

Instrumentation

A 27-item anonymous survey was designed containing both open and closed-ended questions for the specific research questions in this study. The instrument consisted of 2 sections. The first section concerned demographics of the participants. The second section concerned their knowledge of CAI and their preferred treatment approaches. A pilot study of the survey was conducted with 10 physiotherapists to further ensure that it was comprehensible and that its presentation was clear. Revisions of the survey were made accordingly. It was explained to participants in the letter that they should answer questions without consultation of textbooks, colleagues, or other resources, and to describe their treatment based on their day-to-day usage.

Data Analysis

Responses to the demographic questions from section 1 of the instrument (eg, years of experience, postgraduate training) were analyzed using descriptive statistics. A frequency count was performed to reveal the preferred treatments used and background knowledge of CAI. Data were analyzed using commercial statistical software (SPSS, version 15.0; SPSS Inc, Chicago, Ill).

Results

From the 281 questionnaires distributed, 151 were returned completed. Thus, the response rate was 53%.

Section 1

Of the respondents, 64% were female. The largest percentage (43%) did not have postgraduate qualification and was not pursuing further education at the time, 21% did have a postgraduate diploma or certificate, 20% had a Master of Science Degree, 10% were studying for a Masters, and 6% had a PhD. Most respondents had been members of the ISCP for either 2–4 years (24%) or >10 years (31%). The setting in which the respondents were employed varied, but most were employed in hospital outpatients departments (28%) or in private practices (44%).

Section 2

After the demographic information had been gathered, respondents were asked a series of questions about their understanding of CAI, MI, and FI. These answers were compared with commonly accepted definitions outlined in Hertel’s5 CAI paradigm and were deemed either satisfactory or unsatisfactory depending on whether they identified the main themes of each definition. A summary of the respondents understanding of CAI, MI, and FI is presented in Figure 1.

Understanding of Chronic Ankle Instability (CAI), Functional Instability (FI), and Mechanical Instability (MI). (Percent of Participant Responses.)

Figure 1. Understanding of Chronic Ankle Instability (CAI), Functional Instability (FI), and Mechanical Instability (MI). (Percent of Participant Responses.)

Approximately 71% of the respondents were judged to have satisfactory understanding of the meaning of CAI, and the replies indicated that 73% and 71% had satisfactory understanding of MI and FI, respectively. There was a strong overlap between those participants who were able to successfully describe these entities, whereas 21% displayed an unsatisfactory understanding of all 3.

The physiotherapists were then asked to list both the mechanical and functional insufficiencies associated with CAI, and these were also compared with those outlined in the literature.5 There were 4 separate mechanical and functional insufficiencies and deficits associated with CAI. The mechanical insufficiencies included arthrokinematic deficits, pathological laxity, synovial changes, and degenerative changes. The functional insufficiencies and deficits included strength, proprioception, postural control, and neuromuscular. The respondents’ understanding of this is presented in Figure 2.

Identification of Functional and Mechanical Insufficiencies. (Percent of Participant Responses.)

Figure 2. Identification of Functional and Mechanical Insufficiencies. (Percent of Participant Responses.)

Nearly half of the respondents (48%) were able to identify only 1 mechanical insufficiency, but none of the respondents could name all 4. Approximately 21% were unable to identify any mechanical insufficiency. Pathological laxity was identified by all respondents that were able to name at least 1 deficit, and it was the most frequently identified mechanical deficit, listed by 80% of respondents. Arthrokinematics was the second most commonly identified mechanical deficit, although just 17% could name it.

The results showed a better knowledge of the functional insufficiencies than the mechanical insufficiencies. Seventy-one percent were able to name at least 1 functional deficit and 19% were able to name 3 or more. Proprioception was commonly identified as a deficit by almost 70% of respondents, and almost half (49%) identified deficits in strength. Postural control was identified by only 20% of the respondents as a functional insufficiency.

Having established the background knowledge of the conditions, the physiotherapists’ management trends were then ascertained. The results indicated that radiograph and MRI are not commonly used by physiotherapists to help their management of CAI. Approximately 64% and 61%, respectively, use these imaging techniques either sometimes or never. Only 12% always use radiograph, and 8% always use MRI.

The responses suggest that mobilization techniques are commonly used, and each technique listed was used by at least 40% of respondents (always or frequently). The most commonly used techniques were subtalar mobilization (72%), talocrural joint mobilization with movement (68%), and inferior tibiofibular joint mobilization (64%). Of note, 16% of physiotherapists indicated that they always used inversion mobilization as part of their treatment.

In addition, the results suggest that strengthening programs are commonly used, indicating that dorsiflexion (76%), plantar flexion (85%), invertor (77%), and evertor (89%) strengthening protocols were used either always or frequently.

The most commonly used balance training methods were single leg balance exercises (93%), hopping practice (91%), and wobble board training (84%). Jump landing was used by 72% of physiotherapists, and only one-third of respondents used the Star Excursion Balance Test (SEBT) as a balance training measure. The respondents’ preferences of balance training techniques are presented in Figure 3.

Balance Training Methods Used. (Percent of Participant Responses.) Abbreviation: SEBT, Star Excursion Balance Test.

Figure 3. Balance Training Methods Used. (Percent of Participant Responses.) Abbreviation: SEBT, Star Excursion Balance Test.

Functional tests, such as ability to perform multi-directional jumps, perception of pain, swelling, and the patient’s subjective feeling of readiness were the most common outcome measures used to determine suitability for return to sport. The majority (62%) indicated they used taping during rehabilitation, although few indicated which methods of taping were used.

Discussion

The accepted definition of CAI is the presence of residual symptoms such as pain, swelling, and giving way, as well as repeated inversion injury.5 The responses indicated that most of the physiotherapists had a good understanding of this concept; however, their understanding of the insufficiencies associated with CAI was lacking. Understanding the pathogenesis and best management of CAI requires comprehension of the complex interaction of theses insufficiencies that allow for persistent symptoms; therefore, the physiotherapists’ gap in knowledge has implications for their ability to provide best practice for their patients.

Mechanical Insufficiencies

Arthrokinematics. Arthrokinematic restrictions were not readily identified by the respondents. This insufficiency can occur at any of the 3 ankle joints and predisposes the ankle to further sprain. Restriction of physiological range of motion typically occurs after initial sprain,12 and dorsiflexion is most commonly affected.13 When the ankle is unable to achieve dorsiflexion, it is unable to reach its closed pack position and will more readily invert and internally rotate.5 Restrictions of talar glide postlateral ankle sprain has been demonstrated,14 and a recent study has reported a positional fault of the talus.15 This restriction could be a contributory factor to the decrease in dorsiflexion.

Mobilization techniques have been shown to have an ameliorative affect on posterior talar glide and dorsiflexion range of motion.13 Furthermore, it has been suggested that the talus can be displaced anterolaterally on the talar mortise, which would also disrupt the injured lateral ligaments.15 In addition to abnormality of the talocrural joint, anterior displacement of the distal head of the fibula has also shown to be prevalent among those with CAI.16 It is unclear whether repetitive bouts of ankle instability caused the anterior fibular position or the more anterior position was a predisposing factor to injury. Hence, it is interesting to note that despite displaying poor comprehension of arthrokinematic restrictions, mobilizations of the talocrural joint and inferior tibio-fibular joint were commonly used. It is expected that these mobilizations can help to correct or manage the residual positional faults.

Pathological Laxity. This was the most commonly identified insufficiency. Laxity of the ligament after a tear results in hypermobility and allows increased accessory motion at the joint without any ligament tension.17 Studies have shown that despite treatment, 30% of those experiencing lateral ankle sprain appeared to have objective mechanical laxity and subjective instability up to 1 year after an initial ankle sprain.18 This places further strain on the already injured and lax ligaments, initiating a vicious circle.17 The literature suggests the need for more reliable methods of measuring joint laxity, which would allow the physiotherapist to make an informed decision regarding how long the patient is immobilized for and when he or she should begin rehabilitation and return to play.18

Synovial Changes. The presence of synovial hypertrophy and impingement of this tissue has been shown to be present in laterally unstable ankles.19 Ankle impingement syndromes are painful conditions caused by the friction of joint tissues, which are both the cause and the effect of altered joint biomechanics. This suggests that a potential treatment strategy is to normalize joint motion. Few trials have examined conservative management of impingement and, occasionally, surgical debridement of the offending tissues may be indicated.20 The respondents showed poor comprehension of this contributory factor to CAI.

Degenerative Changes. The incidence of osteoarthritis of the ankle has proven to be greatly increased after traumatic ankle sprain and is associated with varus malalignment of the joint,21 which contributes to persistent instability. By reducing the recurrence of injury and preventing the development of CAI, patients may be more physically active and prevent the complications of significant lifestyle change due to previous injury.22 Poor understanding of this insufficiency was found among the respondents.

Functional Insufficiencies

Strength. Until recently, there had been some equivocacy about strength deficits in FI, with several studies offering contrasting evidence over the role of evertor strengthening. However, a recent review23 has demonstrated the role of strength assessment and treatment in rehabilitation and as a criterion for return to play. In addition, selective inhibition of the invertor mechanism has been postulated to be present in FI,24 suggesting a role for invertor strengthening as well. The results of the current study suggest that this is a well understood deficit and that invertor and evertor strengthening is a technique commonly used in the rehabilitation of the FI ankle. Mattacola & Dwyer25 suggested a role for a progressive strengthening program targeting all ankle muscles and progressing from isometric exercise to randomly applied perturbations.

Proprioception. This was the most commonly identified functional insufficiency. It can be divided into 2 distinct components: kinaesthesia and joint-position sense.26 Deficiencies in these lead to the inability to detect motion in the foot, so the foot responds by making postural adjustments, which has shown to predispose to ankle injury.27 This can occur, for instance, with a drop of the lateral border of the foot during swing phase. Balance training modalities such as the wobble board and tilt board, which the respondents in this study reported to commonly use, have been shown as reliable in improving proprioception and postural control.28

Neuromuscular. This was the least commonly identified functional insufficiency. This has been defined as the unconscious activation of dynamic restraints occurring in preparation for, and in response to, joint motion and loading to maintain and restore functional joint stability.29 Caulfield30 and Delahunt31 both reported a deficit in peroneal activity prior to contact with the ground during jump landing. Clark and Burden32 found that wobble board training can positively affect the onset of tibialis anterior and peroneus longus. Thus, the combination of wobble board training, hopping, and jump landing, which were shown to be prevalent among the respondents, is expected to be beneficial as they provide the desired variability in speed and intensity. It is suggested that training using these techniques should be undertaken 2–3 times per day.25

Postural Control. Deficits in postural control have been shown to exist in the FI ankle,33 but the majority of respondents in this study failed to identify it as an insufficiency. These deficits have been shown to occur both in static and dynamic activity. It is accepted that balance training improves objective measures of balance and reduces the rate of re-injury in CAI,22 which could be implemented through wobble board training. Training programs involving balance and coordination exercises can allow for improvements in joint position sense and kinaesthesia10 and decreased incidence of ankle sprain.28 Jump landing and hopping were used by the vast majority of respondents, which are suggested to be useful training techniques to improve time to stabilize measurements. In addition, although respondents displayed limited use of SEBT training, reach deficits have been shown to be negatively affected, which can be improved with training.26 Thus, it is suggested that there could be a greater role for SEBT than currently exists.

Ultimately, in the absence of thorough understanding of functional and mechanical insufficiencies, standard of care inevitably suffers. Although many of the treatments used by therapists can lead to improvements in the insufficiencies, without proper understanding of FI and MI, the principles of evidence-based practice are not being adhered to. Physiotherapists must be aware of what these deficits are so that the patient receives the best possible treatment.

Conclusion and Implications for Clinical Practice

Evidence-based practice is the conscientious, explicit, and judicious use of the best current evidence concerning decisions about the care of individual patients. The practice of evidence-based medicine, as described by Sackett et al,34 means integrating individual clinical expertise with the best available external clinical evidence from systematic research. Although empirical therapy is often indicated, to maintain the highest standards of treatment, physiotherapists must ensure they have a fundamental understanding of the insufficiencies of MI and FI. Without this knowledge, evidence-based practice cannot be ensured, and incidence of CAI will remain high.

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Authors

The authors are from the University College Dublin, Dublin, Ireland.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Eamonn Delahunt, PhD, BSc, School of Public Health, Physiotherapy and Population Science, University College Dublin, Belfield, Dublin 4, Ireland; e-mail: .eamonn.delahunt@ucd.ie

10.3928/19425864-20101029-03

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