Effects of brace wearing and rehabilitation on foot muscle thickness and cross-sectional area after ankle inversion trauma

Abstract-Text (inkl. Referenzen und Bildunterschriften)

Patients suffering from chronic ankle instability (CAI) have lower intrinsic foot muscle volume than healthy controls1. While rehabilitation improves balance and extrinsic foot muscle strength in CAI2, it is unclear if the intrinsic foot muscle strength also increases. Also, little is known about the effect of brace wearing on these muscles after acute ankle inversion trauma. This study aims to analyse the effects of brace wearing and rehabilitation on intrinsic and extrinsic foot muscle thickness and cross-sectional area (CSA) of patients suffering from acute and chronic ankle instability.

Nineteen patients (25±5 years) participated in a rehabilitation programme. Acute patients received an ultrasound assessment within one week of their injury. This was followed by a brace-wearing period of 6 weeks, whereafter rehabilitation started. Ultrasound assessments were performed at the beginning and after 12 weeks of rehabilitation. The muscle thickness and CSA were assessed for Tibialis anterior (TA), Peroneus longus, Flexor digitorum longus, Abductor hallucis, Flexor hallucis brevis (FHB), and Flexor digitorum brevis (FDB). The muscles were analysed individually and as group of in- or extrinsic muscles. A paired t-test was performed to analyse the effects of the brace wearing and 12-week rehabilitation.

The brace wearing caused a significant reduction in muscle thickness of the FDB from 0.76 (0.12) to 0.71 (0,12) cm and of the FHB from 1.31 (0.17) to 1.20 (0.14) cm (Fig. 1). TA thickness increased from 0.56 (0.07) cm to 0.64 (0.06) cm. During the 12-week rehabilitation, a significant increase of the intrinsic foot muscles was observed (Table 1).

Brace wearing in the acute phase is associated with up to 12% loss of intrinsic foot muscles and suggests the need to activate these muscles during this phase. With targeted rehabilitation, the intrinsic foot muscles recover.

References

Feger M, Orth J Spo Med 4(6): 1-8, 2016 Hou Z, J Foot Ankle Res 15(1): 9, 2022