Proximal epiphysis of the second metatarsal: normal trait, possible contribution to growth, and clinical implications.

Analysis of 998 dorsoplantar foot radiographs of 231 patients was performed. Age ranged between 0.21 and 19.94 years. The authors proved the existence of a previously nondescribed additional proximal ossification center in the second metatarsal. This additional proximal center was seen in 78 of 998 radiographs, which corresponds with 7 of the 231 patients. If only 111 patients within the age range in which the additional proximal center appears are considered, the true prevalence of the additional proximal center was found in 7 (6.3%) patients. This additional proximal center was found to be bilateral in 4 (57.1%) of these 7 patients. The presence of the proximal center was more common in girls and was associated with index plus metatarsal type (P=.000) and foot pathology, especially flatfoot (P=.000). Age of appearance was 2.3 ± 0.24 years and age of fusion was 5.5 ± 2.2 years. Using a descriptive maturation scale, the authors classified the ossification stages of the additional proximal center in 4 stages: rudimentary, fully formed, partially fused, and fully fused. After creating a mathematical ratio, the authors could not prove that the presence of this additional proximal center increased the length of the second metatarsal or the complete second ray.