Relationship between calf muscle cross-sectional area and ankle fracture

Whether calf muscles and peroneal muscles have a role in the occurrence of an ankle fractures remains unclear. This study aimed to quantify the calf muscle mass and peroneal muscle mass in patients with an ankle fracture and in controls, then to analyze them together with demographic factors to identify the effects of the regional muscles on the risk of developing ankle fracture.

A total of 101 ankles with computed tomography (CT) images were retrospectively reviewed. Of them, 51 ankles showed fractures (all unilateral) and 50 ankles, in controls who underwent CT for screening the other diseases, were clinically diagnosed with simple contusion. The cross-sectional areas (CSA) of the calf muscles and the peroneal muscles were measured at approximately 6 cm above the Achilles myotendinous junction in the axial plane of ankle CT. These parameters were compared between the two groups and analyzed with respect to age, sex, body mass index (BMI), laterality, and bone attenuations of the ankle.

The demographic factors, including bone attenuation of the ankle showed no significant association with ankle fracture. The ratio of the CSA of the peroneal muscle group to the CSA of the entire calf muscle group was smaller in patients with an fracture (0.12 ± 0.03) than in controls (0.14 ± 0.02) (p = 0.027). The odds ratio for the effect of the calf muscle CSA on the risk of developing ankle fractures was 1.38 (95% confidence interval 1.12-1.69, p = 0.003), whereas that for the effect of peroneal muscle CSA on the risk of developing ankle fractures was 0.18 (95% confidence interval 0.05 to 0.66, p = 0.010).

The ratio of the peroneal muscle CSA to the entire calf muscle CSA was negatively related to the occurrence of ankle fractures in this study. Further prospective studies on whether peroneal muscle-strengthening exercise are effective in preventing ankle fractures may be needed.

III, case-control study.