1. Background
Functional ankle instability (FAI) is the most prevalent complication that occurs in 40% - 50% of the individuals following an ankle sprain. FAI is identified by self-reported instability and giving way during activity and recurrence of ankle sprain. Recurrent ankle sprain may lead to osteoarthritis of ankle joint in the long- term (1-6).
FAI affects sport and activities of daily living, balance, and health status of the individuals (7-9). To treat FAI, balance deficits should be evaluated first. Most studies asses balance deficits using stabilometric devices such as force plates, but these devices are expensive and not available in all clinics. On the other hand, objective clinical tests are more available and reliable (10).
Balance error scoring system (BESS), which was first used to asses mild head injuries (2, 11), is a valid and reliable method to assess static balance. It consists of 6 test conditions: 3 stances (double leg, single leg, and tandem) on 2 surfaces (firm and foam). The results of these tests are correlated with force plate results (10, 12).
The most important complication of patients with FAI is feeling instability and giving way during activity. Ankle instability index is a reliable method for measuring self-reported instability in the ankle (13). SF-36 questionnaire is one of the best tools to measur the health status that affects ankle joint instability.
Despite advances in the treatment of patients with ankle instability and according to the chief complaint of these patients (feeling of instability and giving way that affects activities of daily life), little is known about the correlation between self-reported instability and objective balance tests and health status.
2. Objectives
Thus, the main purpose of the present study was to investigate any correlation of self-reported instability with balance and health status in individuals with chronic functional ankle instability.
3. Methods
3.1. Participants
A total of 23 participants aged 18 to 40 years with functional ankle instability (FAI) (8 males, 15 females, 29.3 ± 4.6 years, 168.9 ± 8.2 cm height, 73 ± 13.8 kg mass) and 23 healthy participants (8 males, 15 females, 30.5 ± 5.2 years, 165.1 ± 7.1 cm height, 70.6 ± 10.2 kg mass) participated in the present study. Participants in the FAI group were matched to the healthy control group by age, body mass index, gender, and dominant leg. None of the participants was an athlete. Simple nonprobability method was used for sample collection. Sample size was obtained through consulting with a statistical specialist and the formula used in rehabilitation research by assuming à = 0/05 and β = 0/2. The power of this study was 80%. The inclusion criteria for FAI group were as follow: 1) any history of unilateral recurrent ankle sprain in the last year; and 2) repeated episodes of giving way or instability during activity in the ankle (2, 14-19). Participants were excluded from both groups under the following conditions: 1) any history of fractures or surgeries or any injuries to either lower extremities; 2) reported visual, vestibular or neurologic dysfunction; 3) acute symptoms of ankle sprain (pain, swelling, redness); 4) bilateral ankle instability; or 5) participation in elite sport activity or current physical rehabilitation program (2, 14, 16-20). The ethical committee of Ahvaz Jundishapur University of Medical Sciences approved the research procedures. The ethical code of the study is ajums.REC.1393.90. All participants read and signed the consent form before participation. Results were presented without mentioning the identity of the participants.
3.2. Procedures
At first, participants performed static balance (BESS) tests, which consist of 6 test conditions: 3 stances (double leg, single leg, tandem) and 2 various surfaces (foam 50 × 60 × 10 cm, firm). Participants had to stand barefoot and as motionless as possible with closed eyes and put their hands on hips for 20 seconds (12). The reliability of these test conditions was 0.78 to 0.96 (10). Participants performed a practical trial at first, followed by 2 trials for each test and 1 minute rest between the trials. Order of the tests was random. Score of each condition was calculated by counting the number of errors (deviations from the proper stance). Errors were as follow: 1) lifting the hands off the hips; 2) moving the hip into more than 30 degrees of flexion or abduction; 3) lifting the forefoot or heel; 3) remaining out of the test position for more than 5 seconds; 5) opening the eyes; 6) stepping, stumbling, or falling (2). The mean score of the 2 trials was used for statistical analysis.
Then participants completed 2 questionnaires: 1) ankle instability index (AII), which consists of 6 dichotomous questions about feeling instability in the ankle (appendix 1 in supplementary file); the maximum score of this index is 6 (participants in the control group scored 0 in this index). According to previous studies, reliability of this index is 0.70 to 0.86 (13, 21); 2) SF-36 questionnaire: this is a valid and reliable questionnaire about physical and mental health status of individuals (22). The physical domain includes physical health, physical function, pain, and general health; and the mental domain includes emotional problem, energy/fatigue, emotional well-being, and social function (22).
3.3. Statistical Analysis
Data were analyzed using SPSS version 19 for windows (SPSS Inc., Chicago, IL, USA), and the significance level was set at p b .05.
At first, Kolmogorov-Smirnov test was used to determine whether data were normally distributed. Comparison between FAI and control groups was done using independent sample t-test or the Mann-Whitney test.
Spearman correlation coefficient was used to determine the correlation between ankle instability index with static balance and health status.
4. Results
FAI group exhibited poorer balance performance than the control group as revealed by independent sample t-test. The number of balance errors in FAI group was significantly more than the control group (P < 0.05) (Table 1). Maximum errors were seen in one leg condition on foam in both groups. No errors were reported in double leg conditions.
Table 1. The Mean ± Standard Deviation and P Value Compared with Static Balance Score Between FAI and Control Groups
| Balance Test | FAI Group | Control Group | P Value |
|---|---|---|---|
| Double leg on firm | 0 ± 0 | 0 ± 0 | - |
| Double leg on foam | 0.1 ± 0.3 | 0 ± 0.1 | - |
| Single leg on firm | 3.8 ± 1.9 | 1.9 ± 1.8 | 0.001 |
| Single leg on foam | 7.3 ± 1.4 | 4.7 ± 1.1 | < 0.001 |
| Tandem on firm | 2.3 ± 1.8 | 0.6 ± 0.8 | < 0.001 |
| Tandem on foam | 3.7 ± 2 | 1.7 ± 1.3 | < 0.001 |
The results of the Mann-Whitney statistical test revealed significant differences in the score of social function, physical health, physical function, and pain subscales of SF-36 between FAI and control groups (P < 0.05). No significant group difference was found for the emotional problem, energy/fatigue, emotional well-being, and general health domains. Overall, there was a significant difference between FAI and control groups in the physical domain, but not in the mental domain. Higher scores showed upper levels of health status (Table 2). Ankle instability index value was 4.3 ± 1.5 in the FAI and 0 in control groups.
Table 2. The Mean ± Standard Deviation and P-Value Compared with SF-36 Questionnaire Score between FAI and Control Groups
| SF-36 Subscales | FAI Group | Control Group | P Value |
|---|---|---|---|
| Physical function | 75.9 ± 21.2 | 91.3 ± 8 | 0.01* |
| Physical health | 67.4 ± 30.6 | 84.8 ± 25.8 | 0.03* |
| Emotional problem | 62.3 ± 40.6 | 76.8 ± 34 | 0.19 |
| Energy/fatigue | 71.5 ± 13.5 | 77.4 ± 14.1 | 0.3 |
| Emotional wellbeing | 70.3 ± 18.9 | 72 ± 17.2 | 0.79 |
| Social function | 69.4 ± 26.4 | 90.2 ± 9.9 | 0.006* |
| Pain | 63.2 ± 17.2 | 82 ± 16.4 | 0.001* |
| General health | 71.7 ± 13.4 | 75.5 ± 14.5 | 0.27 |
| Physical part | 71.5 ± 17.2 | 84.3 ± 12 | 0.01 |
| Mental part | 68.8 ± 19.4 | 76.9 ± 16.4 | 0.12 |
Interpretation of the correlation was as follows: 0 - 0.25: little if any correlation; 0.26 - 0.49: fair correlation; 0.50 - 0.69: moderate correlation; 0.70 - 0.89: high correlation; and ≥ 90 very high correlation (23).
No significant correlation was found between ankle instability index and static balance (P > 0.05). Ankle instability index had a fair to high significant correlation with all the SF-36 subscales except for social function and energy/fatigue (Table 3).
Table 3. P Value and Spearman Correlation Coefficient in the Correlation of Ankle Instability Index with SF-36
| SF-36 Subscales | P Value | Correlation Coefficient |
|---|---|---|
| Physical function | < 0.001* | -0.69 |
| Physical health | < 0.001* | -0.80 |
| Emotional problem | 0.02* | -0.47 |
| Energy/fatigue | 0.06 | -0.39 |
| Emotional wellbeing | 0.03* | -0.43 |
| Social function | 0.2 | -0.27 |
| Pain | < 0.001* | -0.75 |
| General health | < 0.001* | -0.73 |
| Physical part | < 0.001* | -0.85 |
| Mental part | < 0.001* | -0.54 |
5. Discussion
Functional ankle instability is associated with balance deficits and limitations in activity and sport, resulting in decreased health and quality of life. The present study aimed at determining whether any correlation exists between self-reported ankle instability with balance and health status in patients with FAI.
Balance analysis revealed significant differences between FAI and control groups in single limb on firm and foam and tandem on firm and foam surface, but there were no differences in double leg conditions. Results of our study were similar to those of Reimann and Docherty studies (2, 10). Participants in FAI group had a more number of errors and higher scores than the control group. The maximum number of errors was in the single leg on foam followed by single leg on firm and tandem on foam, and tandem on firm surface, but there was not any error in double leg conditions. Docherty et al. also reported similar results. Standing on a single leg makes a smaller base of support and foam surfaces decrease somatosensory information to postural control system (10). Thus, we recommend to asses these 4 tests instead of all other static balance tests.
Health status analysis exhibited significant differences in physical health, physical function, pain, and social function between FAI and control groups. However, no significant difference was found for the emotional problem, energy/fatigue, emotional well-being, and general health domains. Functional ankle instability can influence physical but not mental health of the individuals, and this is against the Anandacoomarasamy and Barnsley’s study. They found significant differences in the general health between ankle sprain and control group, but not in the other subscales (24). This is because the participants of our study were not athletes, so balance problems had not much influence on professional activities. Brent and Arnold achieved similar results to our study in which individuals in FAI group had lower scores in SF-36 physical component compared with the control group (25).
There was a high correlation between ankle instability index with general health, physical health, pain, and physical domain; there was a moderate correlation with physical function and mental domain, and a fair correlation with emotional problem and emotional well-being of SF-36 questionnaire. There was a high correlation between self-reported health status and functional ankle instability, which is the most important problem of these patients. Nonetheless, no correlation was found between ankle instability index and balance tests. Patients’ subjective reports of their problems were not similar to results of objective tests like BESS, and this is because patients’ perception of their problems is affected by their level of activity before the problem, profession, and life style. Thus, objective tests do not involve all aspects of patients’ life.
5.1. Conclusion
Balance problems are associated with ankle sprain. BESS is a valid test to asses balance deficits. Single leg on foam is the most sensitive test among the other 6 conditions of BESS to determine balance deficits. A high correlation of ankle instability index with the physical domain of SF-36 questionnaire revealed that self-reported instability could affect physical health status of the individuals.
