The dysmorphic metatarsal parabola in diabetes—clinical examination and management: a narrative review

Keywords: brachymetatarsia, custom orthosis, foot examination, metatarsalgia, Morton’s extension, podiatry, prescription innersole, shoe insert, short first metatarsal

Abstract

Foot posture and function is important in diabetes, particularly as neuropathy in diabetes may present with motor in addition to sensory neural deficits. Examination of the anatomical architecture of the foot can inform on its load-bearing and balancing function. An examination that does not feature in guidelines on assessment of the diabetic foot is that of assessing whether a metatarsal parabola is present or malformed. The metatarsal ‘parabola’ (in the transverse plane) is so called because the cascade of the differing lengths of the metatarsals form a parabola, defined as the intersection of an arc with a flat (plantar) surface. The parabola serves a function in the rollover motion or forefoot rocker of the foot before heel rise to provide stability and balance in static stance. A further function ensures that the lever-action at the first metatarsophalangeal joint takes place with dorsiflexion of the hallux. This narrative review summarises the literature regarding methods of measuring the metatarsal parabola, dysfunction of the foot due to a dysmorphic metatarsal parabola, clinical relevance, examination and management in diabetes care. It documents the short first metatarsal (SFM) as a risk factor for diabetic foot ulceration. Examination for identification and management of dysmorphic metatarsal parabolae is recommended for foot examinations in diabetes care.

Author Biographies

A T Thompson, University of KwaZulu-Natal

School of Clinical Medicine, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa and Faculty of Podiatric Medicine, Royal College of Physicians and Surgeons, Glasgow, Scotland

B Zipfel, University of the Witwatersrand

Evolutionary Studies Institute, University of the Witwatersrand and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa

C Aldous, University of KwaZulu-Natal

School of Clinical Medicine, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa

Published
2021-08-30
Section
Review Articles