Longitudinal radiographic behavior of accessory navicular in pediatric patients

Abstract

BackgroundAn accessory navicular is generally asymptomatic and discovered incidentally on radiographs. The natural history of an accessory navicular in the pediatric population is largely undescribed.MethodsThe medical charts of 261 pediatric subjects undergoing 2620 annual unilateral radiographs of the foot and ankle (age range 0.25–7 years at enrollment) were reviewed. Radiographs were examined to determine the incidence of accessory navicular, with focus on the age at appearance and, if present, the age at fusion. Skeletal maturity was graded based on ossification pattern of the calcaneal apophysis.ResultsAccessory navicular was identified in 19 subjects (n = 12 males, n = 7 females, p = 0.43), appearing significantly earlier in the female subjects than in the male ones (p = 0.03). Fusion was documented in 42% (n = 8) of subjects, occurring at a mean (±standard deviation) age of 12.5 ± 1.0 years in females and 14.1 ± 2.7 years in males. Skeletal maturity grading demonstrated comparable stages of maturity at the time of fusion between male and female subjects (p = 0.5). Based on an analysis of 160 subjects with serial images extending at least one standard deviation past the mean age of appearance, the overall incidence was 12%.ConclusionOur review of pediatric subjects showed that accessory navicular appeared earlier in females than in males. Fusion occurred in 42% of patients at comparable levels of skeletal maturity between the male and female subjects. No significant differences in overall incidence, skeletal maturity, fusion rate, or age of fusion were noted between the male and female subjects.

Incidence and anatomical variations of accessory navicular bone in patients with foot pain: A retrospective radiographic analysis

“…While not statistically significant, the incidence of Type 2 tended to be higher in females (46.6%) (55/118) than males (39%) (55/141). However, the analysis was limited by a small sample size (Knapik et al, 2016). Our data suggest that bony union (partial or complete) with the body of the navicular is more likely to occur in males.…”

“…They begin as cartilaginous nodules that then undergo endochondral ossification during early to late childhood, between the ages of 3 and 12 years (Williams, 2008;Knapik et al, 2016). They begin as cartilaginous nodules that then undergo endochondral ossification during early to late childhood, between the ages of 3 and 12 years (Williams, 2008;Knapik et al, 2016).…”

“…The accessory navicular forms when the tuberosity of the navicular develops from a secondary center of ossification, and it begins to ossify around 9 years of age in females and 12 in males (Baker et al, 2005;Wheeless, 2012). In regard to ossicle fusion to the main navicular, the AN fuses shortly after its appearance (Cunningham et al, 2016;Knapik et al, 2016). In regard to ossicle fusion to the main navicular, the AN fuses shortly after its appearance (Cunningham et al, 2016;Knapik et al, 2016).…”

“…Accessory ossicles usually result from the failure of secondary ossification centers to generate a union with the main bone. They begin as cartilaginous nodules that then undergo endochondral ossification during early to late childhood, between the ages of 3 and 12 years (Williams, 2008;Knapik et al, 2016). The navicular is the last bone to ossify at age 2-3 in females and 4-5 in males (Baker et al, 2005;Evans, 2010).…”

“…The skeleton of the feet matures on average at 13 years in girls and 15 years in boys (Evans, 2010). In regard to ossicle fusion to the main navicular, the AN fuses shortly after its appearance (Cunningham et al, 2016;Knapik et al, 2016). The factors determining whether ANs unite with the body of the navicular or persist into adulthood are still unexplored.…”