Intra- and inter-observer reliability of the AFCP classification for sagittal plane deformities of the second toe

The French Association of Foot Surgery (AFCP) recently proposed a morphological classification of lesser toe deformities, describing the position of each joint (metatarsophalangeal or MTP, proximal interphalangeal or PIP and distal interphalangeal or DIP) in relation to their anatomic position in the sagittal plane. A study was designed to test its reliability for assessment of sagittal plane deformities of the second toe.

In this retrospective study 55 toes (55 feet, 50 patients) were evaluated. Eleven foot and ankle surgeons assessed independently standardized photographs of each case acquired in a blinded fashion. Assessment was repeated three times, each 15 days apart. Intra- (Intraclass Correlation Coefficient or ICC) and inter-observer reliability (Fleiss' Kappa coefficient) were calculated for each joint.

Intra- and inter-observer reliability were moderate for the MTP joint (ICC range, 0.54-0.61) (Kappa range, 0.53-0.61) and substantial for the PIP (ICC range, 0.60-0.71) (Kappa range, 0.68-0.75) and DIP joints (ICC range, 0.69-0.78) (Kappa range, 0.74-0.78). Mean assessment time±standard deviation was 35±10s per case.

The AFCP classification proved itself reliable in the assessment of sagittal plane defomities of the second toe among eleven foot and ankle surgeons. It is based only on a visual description of the deformity, and does not provide informations on either the clinical reducibility of the deformity and the radiographic joint status.

Level IV, retrospective cohort study.