Is chronic ankle instability associated with contractile thickness of gluteus medius and gluteus maximus during functional movement and exercise? A systematic review and meta-analysis.

Introduction: The gluteus medius (GMED) and gluteus maximus (GMAX) play a crucial role in postural control, and postural control is impaired in individuals with chronic ankle instability (CAI). However, the association between CAI and the recruitment of these muscles remains unclear. The purpose of this study was to explore the contractile thickness of GMED and GMAX during functional movements in individuals with CAI compared to healthy controls.

Evidence acquisition: A systematic search was conducted in six databases (PubMed, Embase, Cochrane Library, Web of Science, EBSCO, and PEDro). Included studies involved the contractile thickness of GMED and/or GMAX comparing CAI with non-CAI. The extracted data were subjected to meta-analysis for observing the differences between the two. The correlation and difference in contraction between GMED and GMAX were analyzed using the Pearson Correlation Coefficient (PCC) and t-test, respectively.

Evidence synthesis: Six studies with 176 participants were found. Contractile thickness measured by ultrasound showed GMED thickness change to be lower in CAI than in controls during functional movements and exercise (WMD: -0.08; 95% CI: -0.11, -0.04; P<0.00001). There was no significant difference between the two groups with respect to contraction of GMAX (WMD: 0.02; 95% CI: -0.01, 0.05; P=0.25). The PCC and P value (t-test) between the ratio of contractile thickness of GMED and GMAX in CAI were 0.397 and 0.029 respectively, indicating activity differences.

Conclusions: CAI may be associated with weaker GMED recruitment during functional movements and exercise, but the activation of GMAX in CAI may be unaffected.