The Abductor Digiti Minimi Muscle

by MASS4D® Prescription Orthotics March 01, 2017

The origin of the abductor digiti minimi muscle involves both, the medial and lateral processes of the posterior calcaneal tuberosity in addition to the plantar aponeurosis and the septum. This muscle inserts at the lateral portion of the proximal phalanx base of the fifth metatarsal.

Among the various causes of heel pain, entrapment of the abductor digiti minimi nerve is one that is challenging to diagnose; if left undetected, this eventually leads to atrophy of the abductor digiti minimi muscle (ADMA).

In a study conducted by Chundru et al. for Skeletal Radiology, 200 individuals with foot pain were divided into a study group composed of 100 individuals with abductor digiti minimi atrophy and 100 individuals without abductor digiti minimi atrophy.

The presence or absence of ADMA was confirmed through a review of MRI reports, with subsequent review of MR images of both groups.

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The findings of the study revealed that patients with ADMA had a significantly greater frequency of conditions such as Achilles tendinosis, calcaneal spur, plantar fasciitis and posterior tibialis tendon dysfunction than those without ADMA.

Selective fatty atrophy of the abductor digiti minimi muscle was established to be a unique sign of bilateral Baxter’s neuropathy by Dirim et al. in their study for the Medical Science Monitor. 

By obtaining MR images for a 42-year-old woman with bilateral Baxter’s neuropathy, high-signal areas in the T1-weighted images and low-signal areas in the T2-weighted images were determined to be associated with fatty atrophy of the abductor digiti minimi muscles in both feet.

In conjunction with these findings, the authors also observed that the woman had plantar fasciitis in both feet.

In order to devise appropriate treatment strategies, it is important to be able to recognise these unique MRI findings which should be considered in early intervention methods for  chronic compression of the inferior calcaneal nerve; the presence of atrophy of the abductor digiti minimi muscle (ADMA) on MRI could be clinically suggestive of Baxter’s neuropathy.

Customised orthotics help in adding strength to the plantar intrinsic muscles such as the abductor digiti minimi, the abductor hallucis, flexor digitorum and quadratus plantae; these muscles are collectively responsible for the stabilisation of the medial longitudinal arch and for the optimal regulation of the rate of pronation.

This becomes an essential component in the treatment of a number of conditions that are synonymous with hyperpronation or atrophy of the intrinsic musculature of the foot.

Copyright 2017 MASS4D® All rights reserved.

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