Ogden J A
Clin Orthop Relat Res. 1982 Jan-Feb(162):112-8.
While accessory ossicles are relatively common in the feet, major developmental chondro-osseous variations in otherwise normal feet appear to be extremely unusual. The "bifid os calcis" has been reported infrequently since its first description by Sever in 1930. The majority of cases are fortuitously diagnosed, usually in children three years of age or older. The current case was diagnosed shortly after birth. The most obvious roentgenographic finding was punctate ossification in the anterior portion. As in other cases, this appeared to be a solitary, bilateral variation of chondro-osseous maturation. Foot development in the fetus includes considerable variation in the development of the calcaneal ossification center and at least two examples of multiple ossification centers.
虽然副骨在足部相对常见，但在其他方面正常的足部出现主要的发育性软骨-骨变异似乎极为罕见。自1930年塞弗首次描述“二分跟骨”以来，其报道并不多见。大多数病例是偶然诊断出来的，通常是在三岁或以上的儿童中。本病例在出生后不久就被诊断出来。最明显的X线表现是前部的点状骨化。与其他病例一样，这似乎是软骨-骨成熟的一种孤立的双侧变异。胎儿足部的发育包括跟骨骨化中心发育的相当大的变异以及至少两个多个骨化中心的例子。
