Interobserver and intraobserver reproducibility of hallux valgus angular measurements and the study of a linear measurement.

BACKGROUND

The intermetatarsal angle (IMA), the hallux valgus angle (HVA), and the lateral sesamoid malalignment in relation to the first metatarsal are among the most commonly employed parameters to estimate the severity of the deformity. The aim of this study was to compare HV angular measurements and a linear measurement among 4 observers to determine its intraobserver and interobserver reliability, to find out whether this linear measurement technique is more reproducible than those already-described angular measurements.

METHODS

The IMA, the HVA, and the distance between the lateral cortex of the first metatarsal and the lateral cortex of the lateral sesamoid bone were measured from 50 standing, nonoperated hallux valgus feet. Radiographs were shuffled and reforwarded to the observers at a minimum interval of 30 days for a new measurement.

RESULTS

When considering 2° of difference as significant, IMA and HVA measurements were not precise, showing low reproducibility for both intraobserver and interobserver assessment. Regarding the distance between the first metatarsal lateral cortex and the lateral sesamoid lateral cortex, when considering differences greater than 2 mm as significant, we observed higher precision and higher reproducibility.

CONCLUSIONS

Angular measurements of hallux valgus deformity in anteroposterior standing radiographs that are manually performed with a goniometer are not precise and have low reproducibility. The linear measurement of the distance between the lateral cortices of the first metatarsal head and the lateral sesamoid demonstrated higher precision and higher reproducibility, and may be a cheap form to assess the correct indication of a distal osteotomy.

LEVELS OF EVIDENCE: Diagnostic, Level II.