Dynamic Postural Stability Deficits in Subjects with Self-Reported Ankle Instability

Single-leg drop landing motor control strategies following acute ankle sprain injury

No research currently exists investigating the effect of acute injury on single-limb landing strategies. The aim of the current study was to analyze the coordination strategies of participants in the acute phase of lateral ankle sprain (LAS) injury. Thirty-seven participants with acute, first-time LAS and 19 uninjured participants completed a single-leg drop landing task on both limbs. Three-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment-of-force) data were acquired for the joints of the lower extremity from 200 ms pre-initial contact (IC) to 200 ms post-IC. The peak magnitude of the vertical component of the ground reaction force (GRF) was also computed. Injured participants displayed a bilateral increase in hip flexion, with altered transverse plane kinematic profiles at the knee and ankle for both limbs (P < 0.05). This coincided with a reduction in the net-supporting flexor moment of the lower extremity (P < 0.05) and magnitude of the peak vertical GRF for the injured limb (21.82 ± 2.44 N/kg vs 24.09 ± 2.77 N/kg; P = 0.013) in injured participants compared to control participants. These results demonstrate that compensatory movement strategies are utilized by participants with acute LAS to successfully reduce the impact forces of landing.

The effects of ankle Kinesio taping on ankle stiffness and dynamic balance

The purpose of this study was to determine the effects of Kinesio® taping on static restraint and dynamic postural control of the ankle joint. Thirty female subjects with no history of ankle injury participated in this study. Subjects were tested for passive ankle laxity and stiffness, and time to stabilization following forward, backward, medial, and lateral hops. Subjects were tested prior to tape application, immediately following application, and following 24 hours of use. Differences between taping conditions were investigated using analyses of variance and pairwise comparisons. Stiffness increased following initial application and 24 hours of Kinesio® tape use (F = 6.99, p = .003), despite no observed changes in ankle laxity (F = 0.77, p = .49); however, no changes were observed in time-to-stabilization (F = 0.03, p = .97). Our results suggest that Kinesio® tape may improve static restraint in the ankle joint without altering peak motion or dynamic postural control. A future investigation into Kinesio® tape efficacy in injury prevention or rehabilitation is warranted.

The relationship between ankle joint physiological characteristics and balance control during unilateral stance

BACKGROUND

The role that the ankle's physiological characteristics play in maintaining balance during quiet stance has been well documented. However, the role of the ankle in maintaining balance during more challenging conditions is questionable. As such, the objectives of this study were to identify any significant relationships between the physiological characteristics of the ankle joint and the ability to maintain more challenging unilateral stance.

PARTICIPANTS

21 healthy, adult athletes (age = 24.67 ± 5.42 years; height = 175.34 ± 7.48 cms; weight = 79.09 ± 14.07 kg).

PROCEDURES

Passive resistance and joint position sense in the sagittal plane of the ankle, and active dorsiflexion range of motion of each subject was assessed, in addition to centre of pressure parameters during 20 s unilateral stance.

RESULTS

Pearson's product moment correlation coefficient found significant positive correlations between D(peaktorque) and sway area (r = .554); A(x) range (r = .449); and A(y) range (r = .471). Significant negative correlations were found between P(peaktorque) angle and sway area (r = -.538, p = .012), A(x) range (r = -.590, p = .005) and A(y) range (r = -.439, p=.046).

DISCUSSION

The results highlighted limited relationships between unilateral stance balance control and the ankle characteristics commonly associated with quiet stance balance control and has, thus, further questioned the role that the ankle plays during more challenging stance conditions. The majority of balance training protocols in the athletic community focuses on the distal joints, however, this needs re-addressing in order to maximise performance.

Foot orientation affects muscle activation levels of ankle stabilizers in a single-legged balance board protocol

CONTEXT

The main goal of balance training is regaining a normal neuromuscular control to a functional level. Although uniaxial balance boards are commonly used, no research has been done on the effect of foot orientation on muscle activation levels.

OBJECTIVE

To investigate the effect of foot orientation on muscle activation levels and modulation of the ankle stabilizing muscles in a single-legged balance protocol on a uniaxial balance board.

METHODS

Sixty-nine healthy subjects (age: 21.8±1.7years; mass: 67.5±11.9kg; body height: 174.7±8.6cm; BMI: 21.5±3.0) participated in this study. Subjects were asked to keep their balance during a single leg stance on a uniaxial balance board for four different foot orientations, aligning the board's rotation axis with frontal, sagittal, diagonal and subtalar axes of the foot, respectively. Surface electromyography registered muscle activity of peroneus longus, tibialis anterior, medial and lateral gastrocnemius muscles.

RESULTS

Highest muscle activation levels and modulation for the peroneus longus were registered exercising along the frontal axis; for the tibialis anterior along the diagonal axis; for the medial gastrocnemius along the sagittal axis; and for the lateral gastrocnemius along the diagonal axis.

CONCLUSION

Foot orientation modifications on a uniaxial balance board allows to differentially target specific ankle stabilizing muscles during balance training.

Intrinsic Predictive Factors of Noncontact Lateral Ankle Sprain in Collegiate Athletes: A Case-Control Study

BACKGROUND

Lateral ankle sprain (LAS) is one of the most common injuries in sports. Despite extensive research, intrinsic factors that predict initial and recurrent noncontact LAS remain undefined.

PURPOSE

To identify the predictive factors of initial and recurrent noncontact LAS, focusing on ankle flexibility and/or alignment in collegiate athletes.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 191 athletes were assessed during the preseason for factors predictive of noncontact LAS. The baseline measurements included weightbearing dorsiflexion range of motion (ROM), leg-heel angle, foot internal rotation angle in plantar flexion, classification according to the mortise test, and navicular-medial malleolus (NMM) distance. Occurrence of noncontact LAS and participation in practice and games were prospectively recorded for 11 months.

RESULTS

Of the 191 athletes assessed, 169 (145 males, 24 females) completed the study; 125 athletes had a history of ankle sprain. During the observational period, 16 athletes suffered noncontact LAS (0.58 per 1000 athlete-exposures) consisting of 4 initial sprains and 12 recurrences. The hazard ratio estimated by a Cox regression analysis showed that athletes with an NMM distance ≥4.65 cm were 4.14 times more likely to suffer an initial noncontact LAS than were athletes with a shorter NMM distance (95% confidence interval, 1.12-14.30) and that athletes with a weightbearing dorsiflexion ROM >49.5° were 1.12 times as likely to suffer a recurrent noncontact LAS compared with athletes with a lower ROM (95% confidence interval, 1.05-1.20).

CONCLUSION

NMM distance predicts initial noncontact LAS, and weightbearing dorsiflexion ROM predicts recurrent noncontact LAS.

The role of arthroscopy in the treatment of functional instability of the ankle

BACKGROUND

Ankle sprains are common, the majority resolving with functional rehabilitation. Some patients are left with symptoms of functional instability (FI). Ankle arthroscopy in those with symptoms of FI is not well covered in the literature. Our aim was to assess its role in FI of the ankle.

METHODS

Retrospective case note analysis of patients with FI following an ankle sprain from 2005 to 2007. All underwent arthroscopy, provided mechanical instability was excluded (EUA and stress X-rays), and there were no signs of soft tissue impingement. These patients had exhausted all options of conservative therapy.

RESULTS

Seventy-seven patients with a mean age of 38.1: five had true mechanical instability and were excluded. 72 underwent arthroscopy: 67 (93.1%) had significant amounts of scar tissue needing debridement, most commonly in the antero-lateral corner (58.3%). 52 patients improved (72.2%) at a minimum of 6 months follow-up.

CONCLUSION

Our study supports the role of ankle arthroscopy in the treatment of FI following trauma. It should be considered when conservative measures have failed.

A Comparison of the Foot and Ankle Condition between Elite Athletes and Non-athletes

[Purpose] The purpose of this study was to compare the foot and ankle condition between elite athletes and non-athletes. [Subjects] The elite athletes group included 85 subjects (28 males and 57 females) and the non-athletes group included 85 subjects (38 males and 47 females). [Methods] All subjects were evaluated for pain (visual analogue scale, VAS) and foot and ankle condition (The Foot and Ankle Disability Index, FADI, and The Foot and Ankle Outcome Score, FAOS). [Results] The elite athlete group showed significant differences from the non-athletes group in VAS, FADI (FADI, FADI-Sports), and FAOS (FAOS-symptoms, FAOS-pain, FAOS-ADL, FAOS-sports, FAOS-QoL). In addition, a meaningful difference in VAS, FADI-Sports, and FAOS-symptoms was observed between gymnasts and wrestlers. [Conclusion] The results of this study suggest the necessity prevention of injury to the foot and ankle of elite athletes, and for the development of exercise for the rehabilitation of foot and ankle injuries, because there is a difference in foot and ankle condition between elite athletes and non-athletes.

Aquatic training for ankle instability

The aim of the present study was to evaluate balance deficits after an ankle sprain in collegiate students and to examine the effectiveness of 2 different balance rehabilitation programs on balance ability. Thirty collegiate students with functional ankle instability were randomly divided into 2 groups. Both groups followed an intervention balance program for 6 weeks, 3 times per week, 20 minutes per session, using balance boards. One of the 2 training groups performed the exercises on the ground-the "Land" group (n = 15), and the other in a swimming pool-the "Aquatic" group (n = 15). Balance ability was assessed before and after the 6-week intervention program. Balance assessments included static (stability indices: total, anterior-posterior, medial-lateral) and dynamic (dynamic moving the cursor) stability tests on the Biodex Stability System (Biodex, Inc, Shirley, NY). The results showed that in both training groups balance ability of the injured leg was significantly improved after the training period. In the final measurements, no statistically significant differences between the injured and healthy limb were found. The present study indicates that the performance of balance exercises in or out of water by collegiate students with functional ankle instability improves their balance ability.

LEVEL OF EVIDENCE

Therapeutic, Level 1.

A systematic review and meta-analysis of dynamic tests and related force plate parameters used to evaluate neuromusculoskeletal function in foot and ankle pathology

BACKGROUND

Force plates are commonly used to register ground reaction forces in order to assess neuromusculoskeletal function of the ankle joint. There exists a great variety in dynamic tests on force plates and in parameters calculated from ground reaction forces in order to evaluate neuromusculoskeletal function of the ankle. The purpose of this study was to evaluate which dynamic tests and force plate parameters are most sensitive to differences between and within groups with regard to foot and ankle pathology.

METHODS

A systematic review and meta-analysis was performed evaluating studies that compared force plate parameters of dynamic tests between patients with foot and ankle pathology, and healthy controls. Data were pooled per parameter and test category. Given the clinical heterogeneity, we constructed comprehensive recommendation criteria to indicate a 'proven relevant parameter' or 'candidate relevant parameter'.

RESULTS

A total of 34 studies were included, and 58 relevant comparisons were identified. Results were subdivided by test category: walking, running, landing (in anteroposterior direction), sideways (movement in mediolateral direction) and termination (movement in anteroposterior direction). The 'walking' test showed significant differences in a great variety of pathologies, with the magnitude and timing of the 'second peak vertical force' as proven relevant parameters. The 'landing' test detected differences due to ankle instability, with 'time to stabilization in anteroposterior direction' as proven relevant parameter.

INTERPRETATION

This study provides recommendations concerning the potential of various dynamic tests and force plate parameters as a tool to compare neuromusculoskeletal function between patients with foot and ankle pathology and healthy controls.

Discriminating between copers and people with chronic ankle instability

CONTEXT

Differences in various outcome measures have been identified between people who have sprained their ankles but have no residual symptoms (copers) and people with chronic ankle instability (CAI). However, the diagnostic utility of the reported outcome measures has rarely been determined. Identifying outcome measures capable of predicting who is less likely to develop CAI could improve rehabilitation protocols and increase the efficiency of these measures.

OBJECTIVE

To determine the diagnostic utility and cutoff scores of perceptual, mechanical, and sensorimotor outcome measures between copers and people with CAI by using receiver operating characteristic curves.

DESIGN

Case-control study.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-four copers (12 men, 12 women; age = 20.8 ± 1.5 years, height = 173 ± 11 cm, mass = 78 ± 27 kg) and 24 people with CAI (12 men, 12 women; age = 21.7 ± 2.8 years, height = 175 ± 13 cm, mass = 71 ± 13 kg) participated.

INTERVENTION(S)

Self-reported disability questionnaires, radiographic images, and a single-legged hop stabilization test.

MAIN OUTCOME MEASURE(S)

Perceptual outcomes included scores on the Foot and Ankle Disability Index (FADI), FADI-Sport, and a self-report questionnaire of ankle function. Mechanically, talar position was quantified by measuring the distance from the anterior tibia to the anterior talus in the sagittal plane. Sensorimotor outcomes were the dynamic postural stability index and directional indices, which were calculated during a single-legged hop stabilization task.

RESULTS

Perceptual outcomes demonstrated diagnostic accuracy (range, 0.79-0.91), with 95% confidence intervals ranging from 0.65 to 1.00. Sensorimotor outcomes also were able to discriminate between copers and people with CAI but with less accuracy (range, 0.69-0.70), with 95% confidence intervals ranging from 0.37 to 0.86. The mechanical outcome demonstrated poor diagnostic accuracy (0.52).

CONCLUSIONS

The greatest diagnostic utility scores were achieved by the self-assessed disability questionnaires, which indicated that perceptual outcomes had the greatest ability to accurately predict people who became copers after their initial injuries. However, the diversity of outcome measures that discriminated between copers and people with CAI indicated that the causal mechanism of CAI is probably multifactorial.

The multiple hop test: a discriminative or evaluative instrument for chronic ankle instability?

OBJECTIVE

To determine whether the multiple hop test should be used as an evaluative or a discriminative instrument for chronic ankle instability (CAI).

DESIGN

Blinded case-control study.

SETTING

: University research laboratory.

PARTICIPANTS

Twenty-nine healthy subjects (21 men, 8 women, mean age 21.8 years) and 29 patients with CAI (17 men, 12 women, mean age 24.9 years) were selected.

INTERVENTIONS

Subjects performed a multiple hop test and hopped on 10 different tape markers while trying to avoid any postural correction.

MAIN OUTCOME MEASURES

Minimal detectable changes (MDC) of the number of balance errors, the time value, and the visual analog scale (VAS) score (perceived difficulty) were calculated as evaluative measures. For the discriminative properties, a receiver operating characteristic curve was determined and the area under curve (AUC), the sensitivity, specificity, diagnostic accuracy (DA), and likelihood ratios (LR) were calculated whether 1, 2, or 3 outcomes were positive.

RESULTS

Based on their MDC, outcomes should, respectively, change by more than 7 errors (41%), 6 seconds (15%), and 27 mm (55%, VAS score) before considering it as a real change. Area under curves were, respectively, 79% (errors), 77% (time value), and 65% (VAS score). The most optimal cutoff point was, respectively, 13.5 errors, 35 seconds, and 32.5 mm. When 2 of 3 outcomes were positive, the sensitivity was 86%, the specificity was 79%, the DA was 83%, the positive LR was 4.2, and the negative LR was 0.17.

CONCLUSIONS

The multiple hop test seems to be more a discriminative instrument for CAI, and its responsiveness needs to be demonstrated.

Movement variability during single leg jump landings in individuals with and without chronic ankle instability

BACKGROUND

Repeated episodes of giving way at the ankle may be related to alterations in movement variability.

METHODS

Eighty-eight recreational athletes (39 males, 49 females) were placed in 4 groups: mechanically unstable, functionally unstable, copers, and controls based on ankle injury history, episodes of giving way, and joint laxity. Lower extremity kinematics and ground reaction forces were measured during single leg landings from a 50% maximum vertical jump in the anterior, lateral, and medial directions. Ensemble curves of 10 trials were averaged and coefficients of variation were identified for ankle, knee, hip, and trunk motion in 3 planes. A log(e) (ln) transformation was performed on the data. Mixed model analyses of variance (ANOVAs) with Tukey post-hoc tests were utilized with Bonferroni corrections to α ≤ 0.008.

FINDINGS

At the knee, controls were more variable than functionally unstable and copers for knee rotation before initial contact, and were more variable during stance than functionally unstable in knee rotation (P ≤ 0.008). Interactions during stance revealed controls were more variable than functionally unstable in lateral jumps for hip flexion, and than mechanically and functionally unstable in hip abduction in the anterior direction (P≤0.008). Controls were more variable than all other groups in hip flexion and than mechanically unstable in hip abduction (P ≤0 .008).

INTERPRETATION

Individuals with ankle instability demonstrated less variability at the hip and knee compared to controls during single leg jump landings. Inability to effectively utilize proximal joints to perform landing strategies may influence episodes of instability.

Inclusion criteria when investigating insufficiencies in chronic ankle instability

INTRODUCTION

The development of chronic ankle instability (CAI) is the primary residual deficit after ankle joint sprain. It has been proposed that CAI is characterized by two entities, namely, mechanical instability and functional instability. Each of these entities in turn is composed of various insufficiencies. Research of functional insufficiencies to date has shown large variances in results. One particular reason for this could be discrepancies in inclusion criteria and definitions between CAI, mechanical instability, and functional instability used in the literature. Thus, we endeavored to undertake a systematic investigation of those studies published in the area of CAI to identify if there is a large discrepancy in inclusion criteria across studies.

METHODS

A systematic search of the following databases was undertaken to identify relevant studies: Cochrane Central Register of Controlled Trials, PubMed, CINAHL, SportDiscus, PEDro, and AMED.

RESULTS

The results of this study indicate that there is a lack of consensus across studies regarding what actually constitutes ankle instability. Furthermore, it is evident that the majority of studies use very different inclusion criteria, which leads to a nonhomogenous population and to difficulties when comparing results across studies.

CONCLUSIONS

Future studies should endeavor to be specific with regard to the exact inclusion criteria being used. Particular emphasis should be given to issues such as the number of previous ankle sprains reported by each subject and how often and during which activities episodes of "giving way" occur as well as the presence of concomitant symptoms such as pain and weakness. We recommend that authors use one of the validated tools for discriminating the severity of CAI. Furthermore, we have provided a list of operational definitions and key criteria to be specified when reporting on studies with CAI subjects.

Effects of ankle and hip muscle fatigue on postural sway and attentional demands during unipedal stance

The effect of muscle fatigue on quiet standing is equivocal, including its duration/recovery and whether it leads to an increase in attentional demands. The purpose of this study was to assess the effects of ankle and hip muscle fatigue on postural sway and simple reaction time during a unipedal task. Two groups of 14 young adults (mean age=22.50±3.23) had to stand on their dominant leg for 30-s trials before and after fatigue of hip or ankle flexors and extensors. Half of the unipedal trials were performed in a dual-task condition where subjects, in addition to standing, had to respond verbally to an auditory stimulus. Sway area, and sway variability and velocity in the AP and ML planes were calculated using center of pressure data obtained from a force platform. Voice reaction time was recorded seated and during the dual-task condition to assess attentional demands. A main effect of fatigue was found for AP sway variability (p=0.027), AP sway velocity (p=0.017) and ML sway velocity (p=0.004). Both groups showed increased sway velocity in both directions and in reaction time during the dual-task condition (p<0.001), but reaction time did not increase with fatigue. A group by fatigue interaction was found significant for ML sway velocity (p=0.043). Results suggest that hip and ankle fatigue affected postural control in the fatigued plane (AP) but only hip fatigue affected postural control in the non-fatigued plane (ML sway velocity). However, fatigue did not lead to an increase in attentional demands and increased AP and ML sway velocity had recovered within 30min.

Alterations in knee kinematics and dynamic stability associated with chronic ankle instability

CONTEXT

Chronic ankle instability (CAI) has been previously and separately associated with deficits in dynamic stability and proximal joint neuromuscular alterations, but how the 2 factors relate is unclear.

OBJECTIVE

To examine the contributions of lower extremity kinematics during an assessment of dynamic stability in participants with CAI.

DESIGN

Repeated-measures case-control design.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty-eight volunteers were categorized into groups of those with unilateral CAI (10 men, 9 women; age = 20.3 +/- 2.9 years, height = 1.77 +/- 0.1 m, mass = 76.19 +/- 13.19 kg) and those without (10 men, 9 women; age = 23.1 +/- 3.9 years, height = 1.72 +/- 0.1 m, mass = 72.67 +/- 16.0 kg).

INTERVENTION(S)

Participants performed 10 jump landings on each limb with a rest period between test limbs.

MAIN OUTCOME MEASURE(S)

Ankle plantar flexion, knee flexion, and hip flexion were captured with an electromagnetic tracking device at the point of ground impact. Ground reaction force data were used to calculate time to stabilization in the anteroposterior and mediolateral planes.

RESULTS

For the anteroposterior plane, we found a group-by-side interaction (P = .003), with the injured side of the CAI group demonstrating reduced dynamic stability. For knee flexion, a group main effect (P = .008) showed that the CAI group landed with less knee flexion than the control group.

CONCLUSIONS

Diminished dynamic stability and decreased knee flexion angle at initial contact were apparent in the CAI group and may play a role in contributing to CAI. This altered kinematic pattern may influence preventive and therapeutic interventions for those with CAI.

Treatment of common deficits associated with chronic ankle instability

Lateral ankle sprains are amongst the most common injuries incurred by athletes, with the high rate of reoccurrence after initial injury becoming of great concern. Chronic ankle instability (CAI) refers to the development of repetitive ankle sprains and persistent residual symptoms post-injury. Some of the initial symptoms that occur in acute sprains may persist for at least 6 months post-injury in the absence of recurrent sprains, despite the athlete having returned to full functional activity. CAI is generally thought to be caused by mechanical instability (MI) or functional instability (FI), or both. Although previously discussed as separate entities, recent research has demonstrated that deficits associated with both MI and FI may co-exist to result in CAI. For clinicians, the main deficits associated with CAI include deficits in proprioception, neuromuscular control, strength and postural control. Based on the literature reviewed, it does seem that subjects with CAI have a deficit in frontal plane ankle joint positional sense. Subjects with CAI do not appear to exhibit any increased latency in the peroneal muscles in response to an external perturbation. Preliminary data suggest that feed-forward neuromuscular control may be more important than feed-back neuromuscular control and interventions are now required to address deficits in feed-forward neuromuscular control. Balance training protocols have consistently been shown to improve postural stability in subjects with CAI. Subjects with CAI do not experience decreased peroneus longus strength, but instead may experience strength deficits in the ankle joint invertor muscles. These findings are of great clinical significance in terms of understanding the mechanisms and deficits associated with CAI. An appreciation of these is vital to allow clinicians to develop effective prevention and treatment programmes in relation to CAI.

Sensorimotor deficits with ankle sprains and chronic ankle instability

The presence of sensorimotor deficits in patients who have suffered ankle sprains or who have chronic ankle instability has been recognized for several decades; however, a body of research literature has developed that elucidates potential physiologic explanations for these deficits. Alterations in a spectrum of sensorimotor measures make it apparent that conscious perception of afferent somatosensory information, reflex responses, and efferent motor control deficits are present with ankle instability. The specific origin of these deficits local to the ankle ligaments or at the spinal or supraspinal levels of motor control have yet to be fully elucidated. It is clear, however, that both feedback and feedforward mechanisms of motor control are altered with ankle instability.

Jump-landing direction influences dynamic postural stability scores

The purpose of this investigation was to determine dynamic postural stability differences among forward, diagonal, and lateral single leg-hop-stabilization protocols in healthy subjects. A one-within repeated measures design was used to determine the effects of jump direction on dynamic postural stability during landing. Subjects were required to perform a two-legged forward, diagonal, and lateral jump to a height equivalent to 50% of their maximum vertical leap, land on a single leg and balance for three seconds. Twenty-six subjects [10 males (22+/-3.9 years of age, 70.9+/-7.6kg, and 176.8+/-6.5cm) and 16 females (20.6+/-.5 years of age, 65.6+/-9.1kg, and 166.4+/-5.9cm)] volunteered to participate in this investigation. Dynamic postural stability indices for the anterior/posterior, medial/lateral, and vertical planes were collected during jump-landing trials of each direction. The results of the investigation show that medial/lateral and vertical dynamic postural stability were significantly affected by the direction of the jump. More specifically, lateral and diagonal jump-landings produce increased medial/lateral stability index (MLSI) scores and forward jump-landings produce increased vertical stability index (VSI) scores. The results suggest that in a healthy population, jump protocol direction will statistically affect dynamic postural stability in the frontal and vertical planes. These alterations could be exacerbated in individuals with lower extremity impairments and further research is warranted.