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S. Arima1, Y. Urabe1, T. Tashiro1, N. Maeda1
1Hiroshima University, Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
Background: Lateral ankle sprain (LAS) has a high incidence and recurrence rate in sports activity (Roos et al., 2017). Although peroneus muscles (PM) are important for preventing the recurrence of LAS, PM dysfunction occurred after LAS. There have been recently increasing reports of morphological changes such as the increased muscle adipose tissues (Sakai et al., 2018), and the decreased cross-sectional area (CSA) in PM after LAS using ultrasonography to identify the factors that contribute to PM dysfunction (Lobo et al., 2016). The proximal 25% or 50% point of PM was previously selected as the ultrasonography measurement point. However, the degree of muscle atrophy varies from proximal to distal in a muscle (Grosset et al., 2008). There are also differences in the morphological changes in PM after LAS depending on the measurement point.
Purpose: This study aimed to clarify the morphological changes after LAS at different points of PM using ultrasonography.
Methods: Four subjects who had experienced two or more LAS and had a positive the anterior drawer test or the varus stress test in unilateral (LAS group) and five healthy subjects (control group) were recruited. B-mode ultrasonography (Telemed, Lithuania) was performed using a linear transducer, and transverse ultrasound images of PM were used for measurements at the proximal 25%, 50% and 75% point between the fibular head and the lateral malleolus in both legs for morphological features (CSA and muscle echogenicity) measurement. Higher muscle echogenicity indicates higher percentage of adipose tissue within the muscle (Pillen et al., 2009). Ankle eversion strength was measured by hand-held dynamometer in lateral position. CSA and echogenicity at each of the three locations and ankle eversion strength were compared by paired t-test, left and right side in control group, affected and non-affected side in LAS group.
Results: LAS group had significantly larger CSA (affected side; 2.67 ± 0.22 cm², non-affected side; 2.23 ± 0.20 cm², p<0.05) and lower echogenicity (affected side; 54.6 ± 4.7, non-affected side; 60.3 ± 3.5, p<0.05) in affected side at 75% point. There was significant difference in ankle eversion strength in LAS group (affected side; 2.30 ± 0.63 N/kg, non-affected side; 2.59 ± 0.63 N/kg, p<0.05).
Conclusion(s): Peroneus Brevis (PB) accounts for most of the PM CSA at the distal 75% point, suggesting that increased CSA and decreased echogenicity occur in PB after LAS. Reflex inhabitation occurred after LAS (McVey et al., 2005), resulting in decreased peroneus Longus (PL) activity (Palmieri et al., 2009). Alternatively, since PB contributes more to ankle eversion than PL (Otis et al., 2004), PB activity may have been high relatively, compensating for the decreased PL activity. However, the ankle eversion strength on the affected side was lower in this study. Increased PB activity does not increase overall ankle eversion strength and may not prevent LAS recurrence.
Implications: Determining the morphological changes in PM after LAS using ultrasonography, measurements at the distal 75% point would help to an accurate assessment.
Funding, acknowledgements: We have no funding acknowledgment in this study.
Keywords: Lateral ankle sprain, Peroneus muscles, Ultrasonography
Topic: Musculoskeletal: lower limb
Did this work require ethics approval? Yes
Institution: Hiroshima University
Committee: Ethical Committee for Epidemiology of Hiroshima University
Ethics number: E-1905
All authors, affiliations and abstracts have been published as submitted.
