Aetiology to Nomenclature

Müller-Weiss diseaseMüller-Weiss disease is an affliction primarily of the navicularNavicular bone with secondary involvement of the perinavicular jointsPerinavicular joints. Its exact aetiologyAetiology remains undetermined despite proposal of various theories. Current consensus is that an overlong second metatarsal or first ray brachymetatarsia leads to eccentric compression of the lateral portion of the navicular. A comma-shaped navicularComma-shaped navicular results with medial extrusion of its medial pole, medial talonavicular subluxationTalonavicular subluxation and lateral shift of the talar head. Delayed ossificationDelayed ossification arising from nutritional deficiencyNutritional deficiency was once considered another major factor predisposing a weakened navicular to deformation under eccentric loading. Another element, as yet unidentified, must be responsible since not all index minus feet go on to develop Müller-Weiss disease. It is not a bipartite navicularBipartite navicular as true partitioning produces two fragments of equal size that do not wander from their normal location. Severe forms of Brailsford’s osteochondritisBrailsford’s osteochondritis and ‘bipartite navicular’ represent advanced stages of the disease, whereby fragmentation of the lateral navicularNavicular occurs, marked medial extrusion of its medial pole and dorsal displacement of the lateral navicular fragment ensue, leaving room for the talar head to articulate directly with the lateral cuneiform bone forming the so-called talocuneiform articulationTalocuneiform articulation that characterizes Maceira end-stage V disease.