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.

Prognostic level II-retrospective study.

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Disorders of the patellofemoral joint are common. Diagnosis and management often involves the use tangential imaging of the patella and trochlear grove, with the sunrise projection being the most common. However, imaging protocols vary between institutions, and limited data exist to determine which radiographic projections provide optimal visualization of the trochlear groove at its deepest point. Plain radiographs of 48 cadaveric femora were taken at various beam-femur angles and the maximum trochlear depth was measured; a tilt-board apparatus was used to elevate the femur in 5-degree increments between 40 and 75 degrees. A corollary experiment was undertaken to investigate beam-femur angles osteologically: digital representations of each bone were created with a MicroScribe digitizer, and trochlear depth was measured on all specimens at beam-femur angles from 0 to 75 degrees. The results of the radiographic and digitizer experiments showed that the maximum trochlear grove depth occurred at a beam-femur angle of 50 degrees. These results suggest that the optimal beam-femur angle for visualizing maximum trochlear depth is 50 degrees. This is significantly lower than the beam-femur angle of 90 degrees typically used in the sunrise projection. Clinicians evaluating trochlear depth on sunrise projections may be underestimating maximal depth and evaluating a nonarticulating portion of the femur.

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