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.     

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.     

Effect of ankle disk training on postural control in patients with functional instability of the ankle joint

The postural control of ten male soccer players with functional instability (FI) of the ankle joint, i.e., recurrent sprains and/or a feeling of giving way, was studied before and after ankle disk training. Postural control was studied by means of stabilometry and an optoelectronic movement recording system. In the present study, we found increased postural sway in men with functional instability, which is in line with previous studies. We found improved postural control after ankle disk training as shown by stabilometry. Postural correction patterns were restored, and segmental displacement amplitudes reached even supranormal values. A subgroup of players with unilateral FI also decreased postural sway when standing on the non-symptomatic, untrained foot after ankle disk training. This bilateral improvement and the restored postural correction pattern do not tally with Freemans proprioceptive theory for postural control, but stresses the importance of central motor programs.     

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.     

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.     

Single-leg postural equilibrium test

The ability to balance on one leg was tested in 29 patients with chronic posttraumatic functional instability of the ankle joint prior to operative exploration of the lateral ligaments of the ankle joint. The results were recorded in seconds and were compared with a control group without functional instability. Patients with ruptured calcaneofibular ligament had a significantly reduced test result compared with patients with uninjured calcaneofibular ligament. Isolated damage to the anterior talofibular ligament did not affect the test result. The patients had a significantly reduced test result on the affected leg, as compared with the unaffected leg and the control group. The single-leg postural equilibrium test is a simple clinical test that is easily used in the objective evaluation of functional instability of the ankle. In chronic functional and mechanical instability, this test seems useful in differentiating between injured and uninjured calcaneofibular ligament.     

Ankle injuries in basketball: injury rate and risk factors

OBJECTIVES: To determine the rate of ankle injury and examine risk factors of ankle injuries in mainly recreational basketball players. METHODS: Injury observers sat courtside to determine the occurrence of ankle injuries in basketball. Ankle injured players and a group of non-injured basketball players completed a questionnaire. RESULTS: A total of 10 393 basketball participations were observed and 40 ankle injuries documented. A group of non-injured players formed the control group (n = 360). The rate of ankle injury was 3.85 per 1000 participations, with almost half (45.9%) missing one week or more of competition and the most common mechanism being landing (45%). Over half (56.8%) of the ankle injured basketball players did not seek professional treatment. Three risk factors for ankle injury were identified: (1) players with a history of ankle injury were almost five times more likely to sustain an ankle injury (odds ratio (OR) 4.94, 95% confidence interval (CI) 1.95 to 12.48); (2) players wearing shoes with air cells in the heel were 4.3 times more likely to injure an ankle than those wearing shoes without air cells (OR 4.34, 95% CI 1.51 to 12.40); (3) players who did not stretch before the game were 2.6 times more likely to injure an ankle than players who did (OR 2.62, 95% CI 1.01 to 6.34). There was also a trend toward ankle tape decreasing the risk of ankle injury in players with a history of ankle injury (p = 0.06). CONCLUSIONS: Ankle injuries occurred at a rate of 3.85 per 1000 participations. The three identified risk factors, and landing, should all be considered when preventive strategies for ankle injuries in basketball are being formulated.     

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.     

Risk factors for noncontact ankle sprains in high school football players: the role of previous ankle sprains and body mass index

BACKGROUND: In a previous study, we noted a possible connection between an athlete's weight and risk of ankle sprain. HYPOTHESIS: A high body mass index and a history of a previous ankle sprain increase the risk of a subsequent noncontact sprain. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: One hundred fifty-two athletes from 4 football teams were observed (2 varsity and 2 junior varsity). Two teams were observed for 3 seasons, and 2 teams were observed for 1 season. Before each season, body mass, height, history of previous ankle sprains, and ankle tape or brace use were recorded. RESULTS: There were 24 ankle sprains, of which 15 were noncontact inversion sprains (11 grade I, 3 grade II, 1 grade III; incidence, 1.08 per 1000 athlete-exposures). Injury incidence was higher in athletes with previous ankle injuries (2.60 vs 0.39; P < .001). Body mass index was also a risk factor (P < .05): injury incidence was 0.52 for players with a normal body mass index, 1.05 for players at risk of overweight, and 2.03 for overweight players. Injury incidence was 0.22 for normal-weight players with no previous ankle sprain compared with 4.27 for overweight players who had a previous sprain. CONCLUSION: An overweight player who had a previous ankle sprain was 19 times more likely to sustain a noncontact ankle sprain than was a normal-weight player with no previous ankle sprain. CLINICAL RELEVANCE: Ankle sprain prevention strategies should be targeted at football players with a high body mass index and a history of previous ankle sprains.     

Examination of static and dynamic postural stability in individuals with functionally stable and unstable ankles.

OBJECTIVE: To determine static and dynamic postural stability differences between functional ankle instability and stable ankle groups. DESIGN: Subjects were required to balance on a single leg and remain motionless for 20 seconds. After completing 3 trials, they performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height. They landed on a single leg, stabilized quickly, and remained motionless for 20 seconds. SETTING: Sports Medicine Research Laboratory. PARTICIPANTS: Subjects with functional ankle instability (n = 14) who reported at least 2 sprains and "giving way" sensations at their ankle joint within the year prior to testing. Fourteen subjects with no history of ankle sprain injury were matched to subjects with functional ankle instability. MAIN OUTCOME MEASURES: Anterior/posterior and medial/lateral mean sway quantified static postural stability during single-leg stance. Dynamic postural stability was quantified with anterior/posterior and medial/lateral time to stabilization during single-leg jump landing. RESULTS: Mean sway was not significantly different between groups in the anterior/posterior (P = 0.28) and medial/lateral (P = 0.65) directions. The functional ankle instability group took significantly longer to stabilize in the anterior/posterior (3.27 +/- 0.72 seconds vs. 2.33 +/- 0.33 seconds; P < 0.001) and medial/lateral (2.48 +/- 0.50 seconds vs. 2.00 +/- 0.65 seconds; P = 0.04) directions. CONCLUSIONS: Individuals with functional ankle instability took significantly longer to stabilize than individuals with stable ankles after a single-leg jump landing. Differences between groups were not detected with mean sway measured during single-leg stance.     

Intrinsic risk factors for acute ankle injuries among male soccer players: a prospective cohort study

This prospective cohort study was conducted to identify risk factors for acute ankle injuries among male soccer players. A total of 508 players representing 31 amateur teams were tested during the 2004 pre‐season through a questionnaire on previous injury and function score (foot and ankle outcome score; FAOS), functional tests (balance tests on the floor and a balance mat) and a clinical examination of the ankle. Generalized estimating equations were used in univariate analyses to identify candidate risk factors, and factors with a P‐value <0.10 were then examined in a multivariate model. During the season, 56 acute ankle injuries, affecting 46 legs (43 players), were registered. Univariate analyses identified a history of previous acute ankle injuries [odds ratio (OR) per previous injury: 1.25, 95% confidence interval (CI) 1.09–1.43] and the FAOS sub‐score “Pain” (OR for a 10‐point difference in score: 0.81, 95% CI 0.62–1.04) as candidate risk factors. In a multivariate analysis, only the number of previous acute ankle injuries proved to be a significant (adjusted OR per previous injury: 1.23; 95% CI 1.06–1.41, P=0.005) predictor of new injuries. Function scores, functional tests and clinical examination could not independently identify players at an increased risk in this study.     

Risk factors for leg injuries in female soccer players: a prospective investigation during one out-door season

The following possible risk factors for leg injuries in female soccer players were studied: age, anatomical alignment, generalized joint laxity, thigh muscle torque, muscle flexibility, ligamentous laxity of the knee and ankle joints, recent injuries, and duration of soccer exposure. A total of 146 players from 13 teams in the second and third Swedish divisions underwent clinical examination, isokinetic measurements of quadriceps and hamstring torques, and testing of postural sway of the legs. All soccer-related leg injuries resulting in absence from at least one scheduled practice session or game were recorded during one outdoor season (April-October). In 50 players there were 61 traumatic injuries, and 17 players sustained 19 overuse injuries. The overall injury incidence rate (traumatic and overuse) was 5.49/1000 h of soccer. Variables significantly increasing the risk of traumatic leg injuries included generalized joint laxity, low postural sway of the legs, hyperextension of the knee joint, and a low hamstring-to-quadriceps ratio during concentric action. Multivariate logistic regression showed hyperextension of the knee joint, a low postural sway, reduced H/Q ratio during concentric action, and a higher exposure to soccer to significantly increase the risk of traumatic leg injury. All five players who suffered an anterior cruciate ligament injury during the study period had a lower hamstring-to-quadriceps ratio during concentric action on the injured side than on their noninjured side.     

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.     

Factors associated with anterior cruciate ligament injury: history in female athletes

AIM: Little is known about the association of lower extremity structural malalignments, flexibility patterns, generalized laxity, postural control, previous ankle sprain history and the increased risk of anterior cruciate ligament (ACL) injuries in females. We hypothesized that females with a history of ACL injury would be more likely to have a history of prior ankle sprain and different structural alignments than females without a history of ACL injury. METHODS: It is a case control study: 33 young adult females with a history of an ACL injury and 33 controls with no history of knee injury provided their knee and ankle injury history and had 16 lower extremity measures taken. RESULTS: The factors most associated with ACL injury history were greater generalized laxity (r(2) change: 0.073), greater genu recurvatum (r(2) change: 0.069), and decreased iliotibial band (ITB) flexibility (r(2) change: 0.069). There was also a significant association between ACL injury history and previous ankle sprain injury history (chi squared=5.27; P=0.02). Those with a history of ACL injury were more likely to have had a prior ipsilateral ankle sprain. CONCLUSION: Increased generalized laxity, greater genu recurvatum, and decreased ITB flexibility discriminated between females with and without history of ACL injury. A relationship linking previous ankle injury and ACL injury risk was found. Taking a thorough medical history and screening for generalized laxity, genu recurvatum, and a tight ITB in those with a history of LAS, may help identify those at risk for an ACL injury and who may benefit most from preventive measures.     

Does a balance deficit persist in Australian football players with previous lower limb ligament injury?

A history of lower limb ligament injury is a commonly-cited risk factor for another similar injury. During the acute phase of injury, there is a balancing skill deficit in the injured limb. It has been unclear as to whether this deficit persists in the medium-to-long term for previously injured Australian footballers, contributing to the risk of re-injury. This study compared the balance ability of footballers with and without previous lower limb ligament injury and, for previously injured players, the balance ability of the previously injured limb to the opposite uninjured limb. A total of 216 players from 6 teams from the Australian Football League were tested. The balance task comprised stepping on to a foam mat on top of a force plate and maintaining one-legged balance. The subjects were divided into 4 groups based on their injury history: all ankle injuries to only one limb, recent ankle injuries to only one limb (within the last 12 months), knee ligament injury only to one limb, and no previous ankle or knee ligament injury. Statistical analysis revealed that there was no significant difference between the balance scores of any of the previously injured players and those with no previous lower limb ligament injury. There was no significant difference between the balance score of the previously injured limb with the opposite uninjured limb. It appears that a balance deficit does not persist in Australian Football players with previous lower limb ligament injury.     

Previous injuries and persisting symptoms in female soccer players

One hundred and fifty players in a female senior soccer division, starting up a new season, were examined for past injuries and persisting symptoms. An incidence of 0.18 injury/player/year was found, which is not significantly different from previously reported injury rates for male soccer. Sprains to the lower extremity and shin-splints were the most common previous injuries. Forty-three percent of the players had some kind of persistent symptom as a result of a past injury. Symptoms from previous ankle and knee sprains and from overuse injuries were the most common. Players who had sustained an ankle joint injury were more prone to have persistent symptoms (p less than 0.05) if they had persistent mechanical instability. Compared to previous retrospective studies on men's soccer, the women showed a higher rate of previous patellar dislocations. These injuries often caused persistent symptoms. The women showed fewer serious knee injuries. This might depend on a real difference in incidence or is just a reflection of female players ceasing to play soccer after a severe knee injury.     

Association between Cumberland Ankle Instability Tool score and postural stability in collegiate soccer players with and without functional ankle instability

ObjectiveThe purpose of this study was to investigate the association between Cumberland Ankle Instability Tool (CAIT) scores and postural stability during a diagonal landing, and to investigate whether postural stability is altered in collegiate soccer players with and without functional ankle instability (FAI).DesignCross-sectional study.SettingLaboratory.ParticipantsNinety-one soccer players were classified into a FAI group (history of at least two ankle sprains and a CAIT-Japanese version score ≤25, n = 28), a copers group (history of one ankle sprain and a CAIT-Japanese version score ≥26, n = 32), or a control group (no history of ankle sprain, n = 31).Main outcome measuresTime to anteroposterior stabilisation (TTSAP) and mediolateral stabilisation (TTSML) were measured during the diagonal single-leg landing.ResultsThe CAIT scores were correlated with TTSAP (P < 0.05, r_s = −0.214) and TTSML (P < 0.01, r_s = −0.566). TTSAP was longer in the FAI group than in the control group, and TTSML was longer in the FAI group than in the other groups.ConclusionsOur findings indicate the presence of an association between the CAIT-J score and TTSML, as well as postural stability deficits in collegiate soccer players with FAI during diagonal landings.     

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.     

The effectiveness of a balance training intervention in reducing the incidence of noncontact ankle sprains in high school football players

BACKGROUND: A high body mass index and previous ankle sprains have been shown to increase the risk of sustaining noncontact inversion ankle sprains in high school football players. HYPOTHESIS: Stability pad balance training reduces the incidence of noncontact inversion ankle sprains in football players with increased risk. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Height, body mass, history of previous ankle sprains, and current ankle brace/tape use were documented at the beginning of preseason training in 2 high school varsity football teams for 3 consecutive years (175 player-seasons). Players were categorized as minimal risk, low risk, moderate risk, and high risk based on the history of previous ankle sprain and body mass index. Players in the low-, moderate-, and high-risk groups (ie, any player with a high body mass index and/or a previous ankle sprain) were placed on a balance training intervention on a foam stability pad. Players balanced for 5 minutes on each leg, 5 days per week, for 4 weeks in preseason and twice per week during the season. Postintervention injury incidence was compared with preintervention incidence (107 players-seasons) for players with increased risk. RESULTS: Injury incidence for players with increased risk was 2.2 injuries per 1000 exposures (95% confidence interval, 1.1-3.8) before the intervention and 0.5 (95% confidence interval, 0.2-1.3) after the intervention (P < .01). This represents a 77% reduction in injury incidence (95% confidence interval, 31%-92%). CONCLUSION: The increased risk of a noncontact inversion ankle sprain associated with a high body mass index and a previous ankle sprain was eliminated by the balance training intervention.