The influence of ankle dorsiflexion and self-reported patient outcomes on dynamic postural control in participants with chronic ankle instability

Highlights

• Decreased dorsiflexion was associated with diminished dynamic postural control.

• Increased ankle stiffness was associated with diminished dynamic postural control.

• Patient-and-clinician generated measures of function should be assessed separately.

Abstract

We investigated the influence of ankle dorsiflexion range of motion (DF-ROM) and self-reported patient outcomes on dynamic postural control assessed with the Star Excursion Balance Test (SEBT) in individuals with chronic ankle instability (CAI). Twenty-nine participants with self-reported CAI volunteered. The primary outcome measurements were categorized into clinician-and patient-generated. Clinician-generated outcome measurements included anterior (SEBT-A), posteriormedial (SEBT-PM) and posteriorlateral (SEBT-PL) reach distances (cm) normalized by leg length (cm) of the SEBT, maximum weight-bearing dorsiflexion (WB-DF) (cm), and open-chain DF-ROM (°). Self-reported patient-generated outcome measures included the foot and ankle ability measure and the level of perceived pain, stiffness, stability, and function of their involved ankle on a 10-cm visual analog scale (VAS). Pearson product moment correlations were used to examine the relationship of the SEBT performances with DF-ROM and self-reported patient outcome measures. A multiple linear regression was performed to determine the influence of patient- and clinician-generated measures on the SEBT. SEBT-A performance was significantly and fairly correlated with WB-DF (r = 0.410, p = 0.014), perceived ankle stiffness (r = 0.477, p = 0.014), and open-chain DF-ROM (r = 0.404, p = 0.015). The strongest predictor of the variance in SEBT-A was the combination of the variance in WB-DF and VAS-stiffness (R² = 0.348, p = 0.004). There were no significant correlations with the SEBT-PM and SEBT-PL. WB-DF and VAS-stiffness may represent targets for intervention that need to be addressed to produce the best outcome in participants with CAI when altered dynamic postural control is detected on the SEBT-A.

Introduction

Chronic ankle instability (CAI) is common following an acute ankle sprain in physically active populations. It has been reported that 32–74% of individuals sustaining an acute ankle sprain develop CAI [1], [2] that is characterized by self-reported disability, pain, repeated episodes of “giving-way,” and/or recurrent ankle sprains [3]. The presence of CAI leads to a decrease in activity level [2] and a lower quality of life [1], [4], and is a leading contributor to the development of posttraumatic osteoarthritis in the ankle [5].

The development of CAI following an initial ankle sprain is highly complex [6], resulting from multiple sensorimotor and mechanical insufficiencies. Impaired sensorimotor control has been demonstrated in individuals with CAI [6], [7], [8], [9], [10], [11], which may manifest as decreased functional performance and diminished postural control [12]. The Star Excursion Balance Test (SEBT) has been described as a reliable clinician-generated measure of dynamic postural control [13]. It has been used previously to show increased risk of acute lateral ankle sprain [14], [15]. Additionally, decreased reach distances of the SEBT and altered proximal joint neuromuscular control has been observed in individuals with CAI [12], [16], which suggests that CAI may constrain the sensorimotor control system. While the SEBT has been used to estimate sensorimotor function in individuals with CAI [13], mechanical insufficiencies, such as mechanical deficits in weight bearing dorsiflexion (WB-DF), are associated with CAI, negatively influencing dynamic control measured with the SEBT-A in CAI populations [17], [18]. Therefore, the SEBT may be a global measure that assesses the ability of individuals with ankle pathology to organize both sensorimotor and mechanical functions.

Assessing ankle dorsiflexion range of motion (DF-ROM) in the weight bearing position has been suggested as a viable alternative to open-chain goniometric measurements of ankle DF-ROM (open-chain DF) [19]. While a relationship between the WB-DF and the anterior reach of the SEBT (SEBT-A) has been shown to be present in individuals with CAI [17], [18], there is little evidence to substantiate any correlation between the SEBT-A, and other directions such as the posteriormedial (SEBT-PM) and posteriorlateral (SEBT-PL), and open-chain DF, as well as between WB-DF and open-chain DF assessments in the CAI population. Decreased ankle DF-ROM has been observed in both the weight bearing and open-chain positions during gait [20], [21]. The availability of DF-ROM in the weight-bearing and open-chain positions could influence ankle motions during functional tasks. Examining interactions among these three measures may provide additional insight into the influence of the availability of DF-ROM on dynamic postural control, and provide a foundation for continued work to identify the most effective interventions after SEBT performance deficiency is detected.

Patient-generated outcome measures have been emphasized in health care [22] and provide valuable information on how the patient experiences physical limitations and disability due to CAI. Various self-reported questionnaire have been developed in previous literature to quantify physical limitations and disability associated with CAI [4], [23]. Enchaute et al. [23] suggested that the foot and ankle ability measure (FAAM) is the most appropriate self-reported questionnaires to assess disability in individuals with CAI. A visual analog scale (VAS) is also commonly used to assess the levels of the typical symptoms (perceived pain, instability, and limited function) across the continuum of disability associated with ankle injuries [24]. The interaction of patient-generated and clinician-generated outcome measures is crucially important to assess how impairments measured with clinician-generated variables contribute to patient-reported functional disability and understanding of the phenomenon of CAI [25]. However, it is unknown how functional impairment measured with the SEBT is related to self-reported functional disability in CAI participants. Examining the correlation between the SEBT and self-reported outcomes may help to improve the identification of deficits related to CAI.

Therefore, the purposes of this study were to determine (1) if the SEBT-A, SEBT-PM, and SEBT-PL are correlated with WB-DF, open-chain DF, and patient-oriented outcomes (FAAM and VAS) in individuals with CAI; and (2) if WB-DF is correlated with open-chain DF in this population. Additionally, we examined which of these variables provided the greatest contribution to global dysfunction measured with the SEBT in participants with CAI.