Stabilometry recordings in functional and mechanical instability of the ankle joint

Functional instability, i.e. recurrent sprains or a feeling of giving way in the joint, is common after ankle sprain. Using stabilometry, an objective and quantitative method for studying postural control, we earlier showed that soccer players with pathological stabilometric results are at risk for ankle joint injury. In the present study we found that the ability to maintain postural equilibrium as demonstrated by stabilometry was reduced among players with functional instability, but was not affected by mechanical instability. The results indicate that coordination and postural control are important for functional instability of the ankle.     

Ankle sprain and postural sway in basketball players

The present study compares postural ankle stability between previously injured basketball players, uninjured players and a control group. Postural sway was recorded and analysed by stabilometry using a specially designed computer-assisted forceplate. Recordings were obtained for 60s on each foot. The stabilometric results in the players with no previous injuries did not differ from those in the controls. Players with a previously injured ankle differed significantly from the control group. These players had a larger mean postural sway and used a larger sway area.     

Postural corrections after standardised perturbations of single limb stance: effect of training and orthotic devices in patients with ankle instability.

OBJECTIVE: Soccer players with functional instability of the ankle joint have shown impairment of postural control in single limb stance. The aim of this study was to examine the effect of stance perturbation. METHODS: A standardised method for the study of postural corrections after perturbation (Equitest) was used. Female soccer players with and without functional instability were examined. RESULTS: The subjects showed a relative change from ankle to hip synergy at medially directed translations of the support surface. This impairment was restored after eight weeks of ankle disk training. The effect of a shoe and brace did not exceed the effect of the shoe alone. CONCLUSIONS: Functional instability seems to be related to impaired ability to retain equilibrium in single limb stance by means of ankle corrections. A positive effect of ankle disk training leading to functional restoration was confirmed.     

Stabilometry in functional instability of the ankle and its value in predicting injury

Stabilometry is an objective method used for studying postural equilibrium quantitatively. Stabilometric recordings were made in 127 soccer players to demonstrate functional instability of the ankle joint. The presence of previous ankle joint injuries, i.e., sprains or fractures, was documented. Reference values for stabilometry were obtained from a group of 30 normally-active non-soccer players without a history of injury to the ankle joint. A pathological stabilometric value was defined as one exceeding the mean value of the reference group by 2 SD. In players with a history of previous ankle joint injury no increased postural sway was found. On the other hand, players showing abnormal stabilometric values ran a significantly (P less than 0.001) higher risk of sustaining an ankle injury during the following season compared to players with normal values. Players with a history of previous ankle joint injury did not run a higher risk compared to players without previous injury. The findings indicate that an ankle joint injury did not result in a persistent functional instability; however, such instability did increase the risk of ankle joint injury.     

Prolonged peroneal reaction time in ankle instability

The peroneal reflex time to sudden ankle inversion and the postural control of 15 athletes with functionally instable ankles were compared with 15 stable controls. A trapdoor produced sudden ankle inversion. Surface electrodes recorded electromyographic activity of the peroneal muscles. Postural sway was expressed by a transverse sway value obtained during single limb stance on a force plate. Increased postural sway was found in subjects with functional instability (p less than 0.01). This is in accordance with previous studies. Functionally instable subjects also displayed an increased peroneal reaction time (p less than 0.01) supporting the theory that functional instability is induced by a proprioceptive reflex defect. Nine of the 15 instable subjects were unilaterally instable and showed lower peroneal reaction time and postural sway values for the stable ankle, but the difference was not significant. There was a high degree of correlation between postural sway and peroneal reaction time (Spearman's rho = .92). In ten functionally instable athletes tested with and without ankle taping, it could not be verified that a reflex enhancing effect of taping occurs through stimulation of cutaneous afferents.     

Prevention of ankle sprains

Two different methods for the prevention of ankle joint injuries in soccer were tested. Coordination training on an ankle disk improves functional stability and postural control, whereas an orthosis provides mechanical support. Both techniques reduce the frequency of ankle sprains in soccer players with previous ankle problems. The orthosis is an alternative to taping, and can be used during the rehabilitation period after injury or when playing on uneven ground. Coordination training on an ankle disk ought to be included in the rehabilitation of ankle injuries to prevent functional instability. It may also be done prophylactically by players with previous ankle problems in order to break the vicious circle of recurrent sprains and feeling of giving way.     

Taping of the ankle — the effect on postural sway during perturbation,before and after a training session

The application of adhesive tape to the ankle prevents spains and is therefore frequently used by athletes with functional instability of that joint. The purpose of the study was to investigate the effect of taping on postural sway during a sudden perturbation in subjects with unilateral functional instability of the ankle joint. Nine Swedish male elite soccer players with unilateral functional instability of the ankle joint after a sprain participated in the study. Their mean age was 25 years. All but one had sustained an ankle sprain during the last 1–12 months, and they applied adhesive tape on one ankle at every practice session and game. Eight moderately active male subjects served as controls (mean age 32 years). Recording and analysis of postural sway was performed by the use of stabilometry. We used a device previously tested for reliability and added a perturbation device. The perturbation device was an ankle disc standing on four bars on top of the force plate. At the start of each recording, the ankle disc was stable. The bars could be removed simultaneously by the test leader. The following parameters were analysed: (1) max sway, the maximal sway amplitude upon perturbation in mediolateral and anteroposterior directions; (2) mean sway, the mean sway during the recording in mediolateral and anteroposterior directions. There was no difference between the right and left ankles before the practice session. The postural sway during perturbation (max sway) decreased when the ankle was taped before the exercise. After the exercise there was no difference between the taped and untaped ankles. The maximum and mean amplitude of sway without tape were smaller after exercise than before exercise. The results in the present study indicate a positive effect of tape on postural sway during perturbation before a practice session. The decreased sway with an untaped ankle after the practice session could mean that the prophylactic effect of taping is most important during the first part of a practice session or a game. Warmer muscle units mean less uncontrolled muscle activity which could result in more effective stabilisation of the ankle joint.     

Effect of ankle disk training combined with tactile stimulation to the leg and foot on functional instability of the ankle

Twenty-two university students with unilateral functional instability of the ankle participated in this study. They were randomly assigned to one of two experimental groups. Subjects in both groups were trained to stand on the affected limb on an ankle disk. In group 1, two pieces of 1-cm wide nonelastic adhesive tape were applied to the skin around the lateral malleolus from the distal third of the lower leg to the sole of the foot before the training sessions. Subjects in group 2 participated in the training sessions without the application of the adhesive tape. Training was performed for 10 minutes a day, five times per week, for a period of 10 weeks. Subjects were tested for postural sway while standing on the affected limb before, during, and after the training period. In group 1, postural sway values decreased significantly after 4 weeks compared with the pretraining performance, and they were within the normal range after not more than 6 weeks of training. In group 2, the values did not improve significantly compared with the pretraining performance until after 6 weeks of training, and they were not within the normal range until after 8 weeks of training. The findings suggest that the 2-week earlier correction of postural sway in group 1 was due to an increased afferent input from skin receptors that were stimulated by the traction of the adhesive tape.     

Pronator muscle weakness in functional instability of the ankle joint

Functional instability, i.e., recurrent sprains or a feeling of "giving way" of the ankle, is common after ankle sprains. These patients have been supposed to have peroneal muscle weakness based on manual methods for measuring muscle strength. We have confirmed this theory by an isokinetic method for testing pronator muscle strength. Pronator muscle weakness on the affected side was found among patients with unilateral functional instability of the ankle joint. Impaired postural control was demonstrated by stabilometry with the patient standing on either foot.     

Ankle joint proprioception and postural control in basketball players with bilateral ankle sprains

BACKGROUND: Deficiencies in ankle proprioception and standing balance in basketball players with multiple ankle sprains have been reported in separate studies. However, the question of how ankle proprioceptive inputs and postural control in stance are related is still unclear. HYPOTHESIS: Ankle repositioning errors and the amount of postural sway in stance are increased in basketball players with multiple ankle sprains. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty healthy male basketball players and 19 male basketball players who had suffered bilateral ankle sprains within the past 2 years were examined. Both groups were similar in age. Passive ankle joint repositioning errors at 5 degrees of plantar flexion were used to test for ankle joint proprioception. The Sensory Organization Test was applied with dynamic posturography to assess postural sway angle under 6 sensory conditions. RESULTS: A significant increase in ankle repositioning errors was demonstrated in basketball players with bilateral ankle sprains (P < .05). The mean errors in the right and left ankles were increased from 1.0 degrees (standard deviation, 0.4 degrees ) and 0.8 degrees (standard deviation, 0.2 degrees ), respectively, in the healthy players to 1.4 degrees (standard deviation, 0.7 degrees ) and 1.1 degrees (standard deviation, 0.5 degrees ) in the injured group. A significant increase in the amount of postural sway in the injured subjects was also found in conditions 1, 2, and 5 of the Sensory Organization Test (P < .05). Furthermore, there were positive associations between averaged errors in repositioning both ankles and postural sway angles in conditions 1, 2, and 3 of the Sensory Organization Test (r = 0.39-0.54, P < .05). CONCLUSIONS: Ankle repositioning errors and postural sway in stance increased in basketball players with multiple ankle sprains. A positive relationship was found between these 2 variables. CLINICAL RELEVANCE: Such findings highlight the need for the rehabilitation of patients with multiple ankle sprains to include proprioceptive and balance training.     

The improvement of postural control in patients with mechanical ankle instability after lateral ankle ligaments reconstruction

Purpose

Lateral ankle sprain is the most common injury. A previous study demonstrated that patients with mechanical ankle instability suffered deficits in postural control, indicating that structural damage of the lateral ankle ligaments may produce a balance deficit. The purpose of this study was to confirm that lateral ligaments reconstruction could improve postural control in patients with mechanical ankle instability.

Methods

A total of 15 patients were included in the study. Each patient had a history of an ankle sprain with persistent symptoms of ankle instability and a positive anterior drawer test and had been treated nonoperatively for at least 3 months. All patients were diagnosed with lateral ankle ligaments tear by ultrasonography and magnetic resonance imaging. They underwent arthroscopic debridement and open lateral ankle ligaments reconstruction with a modified Broström procedure. One day before and 6 months after the operation, all of the participants underwent single-limb postural sway tests. The anterior drawer test and the American Orthopedic Foot and Ankle Society scale score were used to evaluate the clinical results in these patients.

Results

At 6 months after the operation, with the patients’ eyes closed, there was significantly decreased postural sway in the anteroposterior direction, the circumferential area, and the total path length on the operated ankles compared with those measurements before the operation. With eyes open, however, no difference was found in postural sway before and after the operation.

Conclusions

Postural control was improved by reconstructing the lateral ligaments.

Level of evidence

IV.

     

Factors affecting stabilometry recordings of single limb stance

Stabilometry is an objective method for the quantitative study of postural equilibrium and has previously been shown to correlate to functional instability of the ankle joint. Stabilometric recordings of 25 soccer players did not confirm existing theories that an ankle joint injury itself produces a functional instability. Stabilometric recordings of 38 soccer players with and without ankle taping did not show that taping influenced the stabilometric values. In 10 soccer players with functional instability, a significant improvement of stabilometric results and subjective "giving way" feelings were found after 6 weeks of coordination on an ankle disk.     

Postural control deficits in participants with functional ankle instability as measured by the balance error scoring system.

OBJECTIVE: To determine if postural control deficits are present in participants with functional ankle instability (FAI) as measured by the Balance Error Scoring System (BESS). DESIGN AND SETTING: We used a between-groups design to assess postural control. All testing was conducted in a university athletic training facility. PARTICIPANTS: Sixty collegiate Division I athletes were included in this study. Thirty participants had functional ankle instability and thirty participants had no history of ankle injuries. MAIN OUTCOME MEASUREMENTS: Postural control was measured using the BESS. The BESS test battery requires participants to stand unsupported on two different surfaces (firm and foam) in three different stances (double, single, and in tandem). Each condition lasted 20 seconds. The number of errors were calculated for each individual condition and then summed to produce a total BESS score. RESULTS: We found a significant group by condition interaction (F5,290 = 5.12, P < 0.001) and significant main effects for group (F1,58 = 16.01, P < 0.001) and condition (F5,290 = 228.88, P < 0.001). Post hoc analyses revealed that subjects with functional ankle instability scored more errors (poorer balance) on the single stancefirm condition (2.9 +/- 2.1 versus 1.6 +/- 1.3 errors), tandem stancefoam condition (4.3 +/- 2.4 versus 2.7 +/- 1.6 errors), single stancefoam condition (7.0+/-1.6 versus 5.6 +/- 1.8 errors), and total BESS score (15.7 +/- 6.0 versus 10.7 +/- 3.2). CONCLUSIONS: Postural control deficits were identified in participants with functional ankle instability using the BESS. These deficits could be a contributing factor to the repeated episodes of instability and giving way that often occurs following an inversion ankle sprain. These results suggest the BESS, traditionally used for monitoring recovery from mild head injury, may also be useful in screening athletes for postural deficits following lower extremity injury.     

Early influence of an ankle sprain on objective measures of ankle joint function A prospective randomised study of ankle brace treatment

The purpose of this study was to analyse objective modalities of ankle joint function after an acute ankle sprain and to see whether treatment with an air-cushioned ankle brace could enhance the restoration of function compared with a traditionally used compression bandage. The study included 73 consecutive patients between 15 and 55 years of age with an acute grade II or III ankle sprain, who sought medical care within 24 h of the time of injury. Patients with recurrent sprain were excluded. The patients were allocated at random to treatment with compression bandage or an air-cushioned ankle brace (Air-Stirrup, Aircast). The regimen included early motion and weight-bearing in both groups. The patients were examined initially within 24 h, after 3-5 days, 2, 4 and 10 weeks after the injury by the following tests: clinical examination including range of motion, recording of postural sway by stabilometry, joint position sense test, isokinetic eversion-inversion muscle torques and figure-of-eight running. A decreased active range of motion in eversion-inversion was observed during the entire follow-up period. Increased postural sway was registered when standing on the injured foot up to 4 weeks after the injury, as were a deficit in evertor muscle peak torque and an evertor-invertor muscle imbalance compared with the uninjured side. Women demonstrated a greater impairment in postural sway than men. A longer curve running time with the injured ankle at the outside of the curve was noted at the 10-week follow-up. With the exception of running in a figure of eight, these measures were not influenced by treatment with a semi-rigid ankle brace. The methods used in the present study are well suited for further studies of objective modalities of ankle joint function, with the possible exception of the joint position sense test.     

Effects of soft and semi-rigid ankle orthoses on postural sway in people with and without functional ankle instability

Some studies have demonstrated improvement of postural control following use of ankle supports, whereas others reported no effect or even negative effects of bracing. The present study aimed to investigate the immediate effects of soft and semi-rigid orthosis on postural sway in patients with functional ankle instability (FAI). Twenty patients with unilateral FAI and twenty matched healthy individuals participated in the study. Balance in single limb stance on force platform with eyes-open was assessed for both legs while wearing no orthosis (control condition), soft or semi-rigid orthosis. The center of pressure (COP) measures derived from force platform signals were mean total velocity, standard deviation (SD) of velocity and phase plane portrait. A 2 × 2 × 3 (group by foot by orthotics) mixed model analysis of variance was used for statistical analysis. In the FAI group, there was a tendency to lower COP parameters while wearing either of the orthoses, with soft brace having a greater effect. For 2 dependent variables, significant effect of brace was found only for the injured limb. In the healthy group, postural sway increased from no-brace condition, to soft, to semi-rigid orthosis. Both injured and non-injured limbs of patients with FAI had greater postural sway compared to control limbs of healthy individuals.     

The effect of supervised rehabilitation on strength, postural sway, position sense and re-injury risk after acute ankle ligament sprain

The effect of an early rehabilitation program, including postural training, on ankle joint function after an ankle ligament sprain was investigated prospectively. Ninety-two subjects, matched for age, sex, and level of sports activity, were randomized to a control or training group. All subject received the same standard information regarding early ankle mobilization. In addition, the training group participated in supervised physical therapy rehabilitation (1 h, twice weekly) with emphasis on balance training. Postural sway, position sense and isometric ankle strength were measured 6 weeks and 4 months after the injury, and at 12 months re-injury data were obtained. In the training group, there was a significant difference between the injured and uninjured side for plantar flexion (P < 0.01), eversion (P < 0.01) and inversion (P < 0.05), but not for dorsiflexion at 6 weeks. In the control group, there was a significant difference between the injured and uninjured side for plantar flexion (P < 0.01), eversion (P < 0.01), inversion (P < 0.01), and dorsiflexion (P < 0.05) at 6 weeks. Postural sway, but not position sense, differed between the injured and uninjured side in both groups (P < 0.01) at 6 weeks. The side-to-side percent differences were similar in both groups for all variables (P > 0.05) at 6 weeks, and there were no side-to-side differences at 4 months in either group. In the control group, 11/38 (29%) suffered a re-injury, while this number was only 2/29 (7%) in the training group (P < 0.05). These data showed that an ankle injury resulted in reduced ankle strength and postural control at 6 weeks, but that these variables had normalized at 4 months, independent of the supervised rehabilitation. However, the findings also demonstrated that supervised rehabilitation may reduce the number of re-injuries, and therefore may play a role in injury prevention.     

The effects of Kinesiology Tape on static postural control in individuals with functional ankle instability

ObjectiveTo investigate if applying Kinesiology Tape (KT) on the unstable ankle may improve static postural control in individuals with Functional ankle instability.DesignA repeated measured study. Participants performed a series of static quiet bipedal and unipedal stances on a force platform. Measurements were taken at three different times: baseline or no tape, immediately and 24 h after the taping application with the tape remaining on the ankle.SettingA university’s psychomotor laboratory.ParticipantsTwenty young adults with Functional ankle instability aged from 18 to 30 years old. Outcome measures: Postural control was assessed by four measures derived from the centre of pressure data: Area of 95% Confidence ellipse, standard deviation of displacements, mean velocity and mean power frequency. The analysis of variance (ANOVA) was performed to determine any significant improvement in postural control over time due to KT.ResultsOnly minor changes in mean velocity and MPF in unipedal stances were observed immediately after KT application. However, the overall results indicated statistically insignificant improvements in postural control neither immediately after KT application nor after 24 h.ConclusionResults suggest that the use of KT did not affect bipedal and unipedal stances of individuals with functional ankle instability.     

Eccentric muscle strength in functional ankle instability

PURPOSE: To investigate muscle strength in subjects with unilateral functional ankle instability, with the specific aim of determining whether eccentric strength deficits exist. METHODS: Isokinetic invertor and evertor torques were assessed eccentrically and concentrically at speeds of 60 and 120 degrees.s(-1) in 16 subjects with unilateral ankle instability. Absolute peak torque values were compared between the injured and noninjured limbs to determine whether strength deficits existed. RESULTS: No eccentric or concentric evertor strength deficit was found in the injured limb. Interestingly, for the injured limb, a significant interaction effect was found whereby eccentric inversion strength was reduced. CONCLUSION: Functional ankle instability is not associated with deficits in evertor strength. Deficits in eccentric invertor strength were found, and this may contribute to the symptoms of functional ankle instability. Weak invertors may contribute to functional ankle instability because of a reduced ability to assist in controlling lateral displacement of the shank over the weight-bearing foot. Excess lateral postural sway outside of the base of support results in the foot's medial border rising from the floor once the limits of closed chain eversion is reached, which may result in the foot being forced into rapid inversion.     

Individuals with chronic ankle instability exhibit decreased postural sway while kicking in a single-leg stance

Individuals with chronic ankle instability (CAI) usually experience deficits in balance control, which increase displacement in the body's center of pressure (COP) when they balance on a single leg. Little is known, however, about whether or not these individuals use the strategies of postural adjustment properly, especially during functional tasks that may predispose them to ankle sprain. The aim of this study was to investigate anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with and without CAI as they kick a ball while standing in a single-leg stance with their ankle in neutral and supinated positions. COP displacements were calculated and their magnitudes (range) analyzed during APA and CPA intervals and over the duration of the whole task, represented by the COP area of sway and mean velocity. The CAI group exhibited a significant decrease in CPA and area of sway over the whole task, relative to controls. These results suggest that the decreased balance sway could be caused by the need for further stabilization of the ankle in more unstable postures to prevent recurrent sprain. Our findings could help clinicians to better understand the strategies of postural adjustments in individuals with CAI, and may assist and motivate new investigations into balance control interventions in such individuals, as well as proactively address recurrent ankle sprain conditions.     

A multi-station proprioceptive exercise program in patients with ankle instability.

PURPOSE: The aim of the present study was to investigate the effects of a 6-wk multi-station proprioceptive exercise program that is easy to integrate in normal training programs. METHODS: Patients with chronic ankle instability were used, and results of three testing procedures before and afterward were compared: joint position sense, postural sway, and muscle reaction times to sudden inversion events on a tilting platform. A total of 30 subjects with 48 unstable feet were evaluated (exercise group: N = 31; control group: N = 17). RESULTS: In the exercise group, the results showed a significant improvement in joint position sense and postural sway as well as significant changes in muscle reaction times. CONCLUSION: Based on the present results, a multi-station proprioceptive exercise program can be recommended for prevention and rehabilitation of recurrent ankle inversion injuries.