Radiographic considerations of hallux valgus versus hallux rigidus

Metatarsus primus elevatus (MPE) has long been suggested as a primary causative factor in the pathogenesis of hallux rigidus (HR). The purpose of this investigation was to more clearly define this relationship by comparison of first ray position in patients with hallux rigidus, hallux valgus, and a control population with no known foot pathology.

Clinical and radiographical data were retrospectively collected from 297 patients (394 feet) between the periods of January 2007 and September 2008. Patients were stratified into those having isolated HR (110 patients, 145 feet), isolated hallux valgus (HV) (118 patients, 159 feet), and control group (C) of asymptomatic volunteers (69 patients, 90 feet). Any patient with a previous history of foot trauma, surgery, or other foot or ankle pathology was excluded from the study. Standing lateral weightbearing X-rays were obtained for measurement of first to second metatarsal head elevation (Horton Index), Seiberg Index, and Sagittal Intermetatarsal Angle (IMA).

A significant difference in first ray elevation in HR population was identified by all the three measurements. Horton Index (mm) was 6.4 +/- 2.5 for HR population, as compared to 4.0 +/- 2.5 and 3.4 +/- 1.9 for the HV and C populations (p < or = 0.05). Seiberg Index (mm) measured 2.5 +/- 1.8 for the HR group, versus 1.0 < or = 1.6 and 0.24 +/- 0.9 for the HV and C groups respectively (p < or = 0.05). The sagittal IMA (degrees) were 4.5 +/- 2.5 versus 2.7 +/- 2.2 and 1.8 +/- 1.2 (p < or = 0.05).

This investigation does not show any etiological relation between MPE and HR, but identified a correlation between them.