Ankle proprioception deficits have been widely reported in patients with chronic ankle instability (CAI), but their central neuropathological mechanisms have not been fully discussed. So, we aimed to figure out whether the structural and functional features of the cerebellar vermis differed between patients with CAI and healthy controls, and are associated with proprioception deficits in patients.

Twenty-two patients and 25 control individuals were enrolled in a cross-sectional investigation. All participants underwent structural and resting-state functional magnetic resonance imaging scanning to calculate voxel-based morphometry (VBM) and fractional amplitude of low-frequency fluctuation (fALFF) of the vermis. Between-group comparisons of the ankle instability-related subregions of the vermis were performed. Correlation analyses were performed between the outcomes of the surviving subregions and the proprioceptive scores of the ankle inversion discrimination apparatus for landing test.

The subregion of vermis Ⅳ/Ⅴ survived the multiple comparison correction to reveal a lower VBM value in patients than in healthy controls (Cohen's d ​= ​−0.968). The patients also showed significantly higher fALFF (Cohen's d ​= ​0.666) in this subregion. After controlling the demographic features, the proprioceptive scores were significantly correlated with VBM (r ​= ​0.622) and fALFF values (r ​= ​−0.512) in the group of patients.

Patients with CAI have lower gray matter volume and higher activity intensity in the cerebellar vermis than healthy control. The more severe proprioception deficits were significantly associated with the vermal volume and activity, which might be able to facilitate future diagnoses and treatments for CAI.

Postural control deficits and persistent joint stability issues are prevalent in population with anterior cruciate ligament (ACL) injuries or reconstructions. Postural control is typically assessed using the center of pressure (CoP) parameters during the static single-leg stance with a force plate. However, previous studies have reported unclear definitions and descriptions of the CoP parameters, causing inconsistent results of postural control deficits in a specific population.

To 1) summarize CoP parameters commonly used to evaluate postural control deficits in ACL injured or reconstructed population, and 2) identify the differences in CoP parameters with opened and closed eyes during the single-leg stance between ACL injured or reconstructed and control groups.

PubMed, Embase, Cochrane Library, CINAHL, Scopus, Web of Science, and SPORTDiscus databases were searched up to July 2023. Data were obtained from the selected articles and underwent quality and risk of bias assessment and meta-analysis using random-effect models. Subgroup analysis within ACL injured or reconstructed group were also performed.

A total of 14 articles were included in the analysis after screening. The injured knee of the ACL injured or reconstructed group differed insignificantly in sway amplitude, sway area, and sway velocity during static single-leg stance under opened and closed eyes when compared with the control group. In the subgroup analysis, we found that there was only significant difference in sway velocity with open eyes (SMD ​= ​0.47, p ​= ​0.001) between ACL reconstructed group and control group.

This study summarized the common CoP parameters used to evaluate postural control in ACL injured or reconstructed population. The results only showed weak difference in sway velocity between ACL reconstructed population and healthy individuals with opened eyes during the static single-leg stance.