Intra- and interobserver repeatability of radiographic measurements in hallux surgery: Improvement and validation of a method

Abstract

To test the hypothesis that the reproducibility of radiographic measurements of the first metatarsophalangeal angle and the intermetatarsal angle I-II can be increased by exact guidelines, we calculated the intra- and interobserver reliability of both methods. 4 independent observers (2 senior residents and 2 orthopedic trainees) evaluated 50 pre- and 50 postoperative plain dorsoplantar radiographs with their method of preference and then with Mitchell et al.'s method (1958). The mean intraobserver coefficient of repeatability for the metatarsophalangeal angle improved from 5.9 degrees to 4.2 degrees and for the intermetatarsal angle I-II, from 4.4 degrees to 2.8 degrees. The interobserver coefficient of repeatability improved from 6.5 degrees to 5.0 degrees for the metatarsophalangeal angle, and from 4.9 degrees to 3.6 degrees for the intermetatarsal angle I-II. This improvement in measurement accuracy was more marked for postoperative measurements, due to deformation of the metatarsal after the osteotomy which made it more difficult to find the longitudinal axis of the metatarsal. The improvements in the accuracy of measurements were also greater in the two inexperienced observers, since their measurements differed more when they had no exact guidelines for their drawings.

Validity and Reliability of Hallux Valgus Angle Measured on Digital Photographs

“…We determined from the literature that up to 6.5° of variation can be seen when more than 1 examiner measures radiographic HV angle. 27 Therefore, this amount of error was considered an appropriate clinical standard for our analysis. Our results showed LA within this range, indicating that photographic measurements of HV angle can be confidently used as an alternative to radiographs.…”

“…7 An acceptable range for 95% LA between photographic and radiographic measurements was determined a priori to be 6.5°, which is the reported interrater RC for radiographic measurement of HV angle. 27 Statistical analyses were conducted using Stata Version 10 (StataCorp LP, College Station, TX).…”

A comparison of hallux valgus angles assessed with computerised plantar pressure measurements, clinical examination and radiography in patients with diabetes

“…In the literature, radiographic measurement of HVA is described as the “gold standard” and commonly used by foot and ankle specialists [12,13]. An additional advantage of radiography is the possibility to evaluate more important information of the bony structures of the foot, especially preoperative.…”

The influence of personality traits on the subjective outcome of operative hallux valgus correction

“…Preoperative antero-posterior and lateral weight-bearing radiographs were compared to radiographs obtained at the last follow-up visit. The examination included measurement of hallux valgus and intermetatarsal angles [13]. The aim of the operative procedure was to correct the deformity with a resultant hallux valgus angle of less than 15°and first-second intermetatarsal angle less than 9° [1].…”