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

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.