Incidence and Determinants of Recurrent Lateral Ankle Ligamentous Sprain

Research Article

Phys Med Rehabil Int. 2015; 2(8): 1064.

Incidence and Determinants of Recurrent Lateral Ankle Ligamentous Sprain

Kemler E¹*, Badenbroek IF1,2, Port IGL van de1,3, Hoes AW² and Backx FJG¹

¹Department of Rehabilitation, Nursing Science and Sports, Division Neuroscience, University Medical Center, Utrecht, the Netherlands.

²Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, the Netherlands.

³Revant Rehabilitation Center Breda, Brabantlaan 1, Breda, the Netherlands

*Corresponding author: Kemler E, Rudolf Magnus Institute of Neuroscience, Department of Rehabilitation, Nursing Science and Sport, University Medical Center Utrecht, Utrecht, PO Box 85500, 3508 GA, the Netherlands

Received: September 26, 2015; Accepted: October 20,2015; Published: October 26, 2015


Objective: Little is known about the incidence and determinants of recurrent acute lateral ankle ligamentous sprain (ALALS) in the general population. Our purpose was to determine the proportion of patients suffering from recurrent ALALS during one year follow-up after the initial injury and to identify risk factors for sustaining a recurrent ALALS.

Design: Prospective cohort study.

Setting: Patients were recruited from 20 family practices, nine physical therapy practices and emergency departments of two hospitals.

Subjects: Adult patients with an ALALS caused by inversion trauma.

Methods: Univariable and multivariable Cox regression analysis.

Results: After 52 weeks follow-up, 29 of the 157 patients (18%; 95% CI 12.4- 24.5) had experienced an ALALS. Univariable analysis showed that younger age, a lower BMI, having had more than one ankle injury, sports participation and the number of hours of sports per week was associated with the risk of recurrent ALALS. Multivariable analysis showed that with increasing age the risk to suffer an ALALS decreases (HR 0.92 (95% CI 0.87-0.98).

Conclusions: Nearly one fifth of the patients with ALALS suffer from a re-injury within 12 months and the injury risk decreases with increasing age. This highlights the importance of optimal treatment and preventive programs in younger adults.

Keywords: Ankle sprain; Re-injuries; Risk factors; Prognosis; Prevention


ALALS: Acute Lateral Anke Sprains; HR: Hazard Ratio; OR: Odds Ratio; CI: Confidence Interval; BMI: Body Mass Index; UMC: University Medical Center; ICE: Immobilization, Compression and Elevation; NSAIDs: Non-Steroidal Anti-Inflammatory Drugs; SD: Standard Deviation; h: Hours; N: Number; β: β-coefficient; SE: Standard error of the Estimate


After the knee, the ankle is the most injured body site in athletes (11% to 21%) [1]. Depending on the population studied, ankle sprains account for by to of all ankle injuries in athletes [1]. Reported incidence rates for ankle sprains in the general population vary from 1.5 up to almost 7 per 1,000 person-years [2-5]. Most ankle sprains (85%) are located on the lateral side [6].

The consequences of acute lateral ankle ligamentous sprains (ALALS) can sustain over a long period of time. One of the most important long-term consequences is recurrent ALALS, although studies reporting on the incidence of recurrent sprains tend to report large differences. A systematic review by van Rijn et al. (2008) showed that 3 to 34% of the patients suffer a recurrent ALALS of the injured ankle within 3 years [7]. The highest rates of recurrent lateral ankle sprains are reported among athletes, mainly active in team sports [8,9]. The mean time to return to sports after a recurrent sprain seems to be higher than after a first-time ankle sprain [10]. A recurrent ALALS causes longer absence of players in team sports [10] and causes additional work absenteeism in the general population [11].

From earlier research it is known that a previous lateral ankle sprain in an athlete’s history is one of the most important risk factors for sustaining an ankle sprain [12,13]. It is useful to identify people who is increased risk of sustaining a recurrent sprain, because the occurrence of a recurrent sprain has a large impact on a patient’s daily functioning and sports participation. In addition, information about risk factors for recurrences yields important input for targeted preventive strategies.

Two earlier studies identified risk factors for a recurrent ALALS. Pre-injury activity level [14] and grade of initial injury [10] were significant predictors of recurrent ALALS. However, one study [14] included only athletes and neither of these studies performed multivariable analysis and thus did not identify independent predictors.

The purposes of this study were to determine the proportion of patients (athletes and non-athletes) that suffer one or more recurrent ALALS during the first year after the initial injury and to identify determinants of sustaining a recurrent ALALS.


Study design

This prospective cohort study was part of a controlled trial on treatment of acute lateral ankle ligamentous sprains [15]. Between May 2006 and October 2008, 164 patients were recruited for this pragmatic multi-center trial of which 157 were eligible for inclusion. Patients were randomly allocated to 4-week functional treatment with either a soft ankle brace or ankle tape. The protocol for this study was approved by the medical ethics committee of the University Medical Center (UMC) Utrecht. All patients included gave their written informed consent. The results of the trial showed no significant differences between the two treatment groups [15]. Based on this conclusion, both study groups were combined to one cohort of patients for the present study.


Patients were recruited from 20 general practitioner practices, nine physical therapy practices (region of Utrecht, the Netherlands) and the emergency departments of two hospitals, namely Zuwe Hofpoort hospital in Woerden and the UMC Utrecht, both in the Netherlands. All included patients suffered an ALALS due to an inversion trauma within 14 days previous to inclusion. Patients were excluded if they were younger than 18 years, if they suffered an eversion trauma, multiple trauma or complicated trauma (including cartilage injuries and dislocation), or had a history of ankle surgery. Patients with documented mental illness or cognitive impairment were also excluded from this study.


All patients were treated according to the ICE-protocol (Immobilization, Compression and Elevation) during the acute period. Functional treatment (tape or brace) started as soon as possible but at least within 14 days after the initial trauma. At initial treatment, no specific pain medication protocol was prescribed; patients were allowed to take pain medication, including non-steroidal anti-inflammatory drugs (NSAIDs) at their own convenience. Baseline measurements of all patients were obtained in a standardized manner by a sports physician. Participants were asked to fill out online questionnaires at 5, 9, 13, 26 and 39 weeks after the initial ankle sprain. In week 52, a final questionnaire was combined with a physical re-examination by a sports physician.

Outcome variable

The outcome variable, recurrent ALALS, was defined as an inversion trauma of the same ankle affected at baseline [15]. Other injury types (e.g. strain, fracture, and overload) were not classified as ALALS. Information on the outcome variable was obtained from the self-reported online questionnaires during the follow-up period and the final questionnaire administered at 52 weeks.

Determinants of recurrence

The following potential determinants were measured: gender, age, body mass index (BMI), the number of ankle injuries in the patients’ history, having had an ankle injury within one year prior to the start of the study, sports participation, the severity of the initial ankle sprain and the allocated treatment.

To gain more insight into the age distribution, age was divided into quartiles. BMI was calculated as weight/ length² (kg/m2) and divided into normal weight (≤ 25) and overweight (>25). The number of ankle injuries in a patients’ history included the initial injury from this study and was dichotomized in one and more than one. Sports participation at baseline was reported as yes or no and in mean number of hours of sports participation per week. The hours of sports participation were also divided into quartiles. No definition of sports was given in advance. The severity of the ankle sprain at baseline was classified into three categories: mild, moderate or severe. The severity score was based on data from the physical examination at baseline, corrected for the number of days between the physical examination and the initial inversion trauma (see Appendix A).

Statistical analysis

Baseline characteristics were described using mean with standard deviation (SD), range or frequencies, where appropriate. The 1-year incidence of a recurrent acute lateral ankle ligamentous sprains were compared for categories of the potential determinants using Chi-square or (for dichotomous variables) Fisher-exact test. In this analysis, age and hours of sports were into quartiles and BMI was dichotomized (normal weight ≤ 25 kg/m2 and overweight > 25 kg/m².

Multiple imputation was used to assess missing data (n=18) for ankle sprain recurrences. Sensitivity analyses were performed with complete cases only (n=139).

The association between each determinant and the occurrence of a recurrent sprain was examined using univariable Cox regression analysis. All variables were tested for the proportional hazards assumption. If the interaction term between the variable and the natural logarithm of time was not significant (p>0.05), the proportional hazards assumption was considered being met [16]. Variables with a p-level of <0.1 in the univariable analysis, showing no multicollinearity, were included in a multivariate Cox regression analysis. The p-level of 0.1 was chosen liberally to avoid that possible predictors were missed in the multivariable analysis. Multicollinearity was tested by obtaining variance inflation factors (VIF) and tolerance values, a VIF value <10 and a tolerance value >0.1 was interpreted as no indication for multicollinearity [17]. All data were analyzed using IBM SPSS Statistical software package (version 23.0).


In total, 157 patients were included in the trial. The baseline characteristics of the study population are presented in Table 1. Patients had a mean age of 31 years (SD 11.6), a mean BMI of 24.5 kg/ m2 (SD 4.27) and 88 participants (56%) were male. Participants in this study had to fill out six questionnaires during the 1-year follow-up period. For 11% of the participants (n = 18) data were not complete at the end of the clinical trial. Nine participants did not fill out the last questionnaire, one participant missed three measurements, another one missed four measurements and one participant did not fill out five questionnaires. Six participants did not fill out any questionnaire.