Introduction: Hallux valgus (HV) deformity increases width of the forefoot. Criteria for a successful outcome after surgery include resolution of pain, a narrower forefoot and ability to wear conventional shoes. Skeletal width of the forefoot can be objectively measured on radiographs by a recently introduced parameter called the metatarsal span (MS). Reduction in MS can therefore be used as an outcome indicator. It is however not known if MS can be measured reliably. It is hypothesized that MS which is a linear parameter can be measured as reliably as the HV and intermetatarsal (IM) angular parameters.

Methods: Digitized pre and postoperative weight bearing radiographs of twenty patients with HV were evaluated by six observers. HV and IM angles and the MS were measured using digital techniques. ANOVA was used to study inter-observer and intra-observer reliability. A 95% confidence interval was determined.

Results: Inter and intra-observer agreement was present for all measurements. 95% CI for intra-observer pre and post operative measurements were ± 5° and ± 5° for HV angle, ±2° and ± 3° for IM, and ± 1.0mm and ± 3.0mm for MS. 95% CI inter-observer pre and post operative measurements were ± 4° and ± 4° for HV angle, ± 3° and ± 2° for IM angle, and ± 1.0mm and ± 2.1 mm for forefoot width, respectively.

Conclusion: Digital measurements of the linear parameter MS can be obtained as reliably as angular parameters HV and IM angles.

One of the criteria associated with success after hallux valgus surgery is reduction of the forefoot width. A new parameter called the metatarsal span can be a reliable objective measure to assess reduction of forefoot width and outcome after surgery for hallux valgus.