The Linear Hallux Valgus Offset- A novel way to measure Hallux Valgus.

Introduction: Hallux Valgus (HV) is a complex deformity involving the first ray of the forefoot and a common cause of forefoot pain. Several radiological measurements such as Hallux Valgus Angle (HVA), First Metatarsophalangeal Angle (IMA) and Distal metatarsal articular angle (DMAA) exist to calculate the severity of HV and direct patient management. However, these are angular measurements are prone to error with variable intra- and inter-observer reliability. Purpose: To describe a new radiological linear hallux valgus offset (LHVO) to measure HV deformity. Patient and methods: We performed a retrospective cohort study looking at Antero-posterior, weight-bearing foot radiographs of 100 consecutive patients with forefoot pain referred to our foot and ankle clinic. Demographic details, clinical indication, HVA (hallux valgus angle) and LHVO were measured for each patient and data were analyzed using the student t-test. Intraclass Correlation Coefficient (ICC) analysis was evaluated to assess the intra-class reliability between observers. Results: There was a female predominance of approximately 2:1, with 51.3 years (range 13-86 years). There was a statistically significant difference of LHVO between normal and hallux valgus cohorts with a p-value of 0.0001. The LHVO gave moderate intra-observer and inter-observer reliability on ICC analysis of 0.7. Conclusion: The LHVO can be an additional measure of assessing severity of hallux valgus. In contrary to the traditional angular measurements, this linear measure is easier to calculate and reproducible on plain, weight bearing radiographs. LHVO measurement has shown a moderate inter-observer reliability in the study to complement traditional radiological evaluation of hallux valgus alignment.