The Controversial Definition of Normal Toe Alignment

Abstract

“Normal” and “abnormal” are frequently used in surgical planning and to evaluate surgical results of the forefoot. However, there is no objectifiable value of metatarsophalangeal angles (MTPAs) 2–5 in the dorsoplantar (DP) view with which to objectively evaluate lesser toe alignment. We aimed to determine which angles are considered to be “normal” by orthopedic surgeons and radiologists. Thirty anonymized radiographs of feet were submitted twice in randomized order to determine the respective MTPAs 2–5. After six weeks, the anonymized radiographs and photographs of the same feet without apparent affiliation were presented again. The terms “normal,” “borderline normal,” and “abnormal” were assigned by the observers. Viewers considered MTP-2 alignment from 0° to −20° to be normal, and below −30° abnormal; MTP-3, 0° to −15° to be normal and below −30° abnormal; MTP-4, 0° to −10° normal and below −20° abnormal. Between 5° valgus and 15° varus was the range of MTP-5 recognized as normal. High intra-observer but low interobserver reliability with overall low correlation of clinical and radiographic aspects was observed. The assessment of the terms “normal” or “abnormal” are subject to a high degree of variation. Therefore, these terms should be used cautiously.

Keywords

• toe alignment
• forefoot
• parabola
• metatarsophalangeal angle
• transverse plane