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Updated: May 6, 2026
Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
Published on: April 17, 2019
Mri-detected low-lying and hypertrophic muscle bellies are associated with the occurrence of peroneal tendons
Xiaoli Gou1, Xiaoqi Yi2, Zhenyu Wang1
1Department of Sports Medicine, The First Affiliated Hospital of the Army Medical University, Chongqing 400038, China.
Objective:
To investigate the correlation between MRI-defined anatomical features and peroneal tendon dislocation (PTD) by comparing the characteristics of the peroneus brevis muscle belly (PBMB) in patients with those in a control group, with the hypothesis that an increased prevalence of enlarged and distally extended muscle bellies is associated with PTD cases.
Methods:
This case-control study included 33 patients in the PTD group and 33 matched controls in the normal control (NC) group. MRI scans were conducted to measure the peroneal tendons cross-sectional areas (PTCA) and peroneus brevis muscle belly cross-sectional areas (MBCA) at five levels: one at the ankle joint center and the adjacent proximal and distal slices (1 proximal, 3 distal), calculate the muscle belly ratio (MBR), and determine the height of the distal endpoint of muscle belly (HMB).
Results:
PTCA showed no significant differences between the two groups across five levels. The PTD group exhibited significantly larger MBCA and MBR at all levels, notably at level 1 (proximal slice), level 2 (ankle joint center), and level 5 (p < 0.001). Moreover, the PTD group exhibited a lower HMB compared to the NC group (1.3 ± 5.4 mm vs. 9.0 ± 6.5 mm, p < 0.001). HMB showed an AUC of 0.838 with an optimal cutoff of 8.20 mm; MBR at Level 1 showed an AUC of 0.843 with an optimal cutoff of 68.86 %. The recommended thresholds are 8.00 mm for HMB (sensitivity 0.909, specificity 0.667) and 69.00 % for MBR at Level 1 (sensitivity 0.788, specificity 0.788).
Conclusion:
PTD is correlated with hypertrophied peroneus brevis muscle bellies and distally extended muscle bellies. Defining low-lying muscle belly (LLMB) as the PBMB positioned ≤8 mm proximal to the fibular tip with an MBR of Level 1 > 69 % enhances precise identification.
