Developmental Patterns of the Greater Trochanter in Skeletally Immature Patients.

BACKGROUND: Trochanteric entry femoral nailing in immature patients is controversial. Although it has become increasingly accepted in pediatric patients aged 8 years and older, complications related to physeal violation have been reported. To date, the appropriate minimum age for safe antegrade nailing in skeletally immature patients remains to be unknown. The purpose of this investigation was to determine the degree of trochanteric bony and cartilage growth with increasing age to provide normative growth values.

METHODS: A total of 408 serial digitized radiographs of the left hip in 45 healthy children (n=26 female individuals, n=19 male individuals) between the ages of 6 and 14 were retrospectively reviewed by 2 independent authors. Radiographs were examined to measure the changing height of the bony greater trochanter with increasing age. Magnetic resonance imaging (MRI) scans of 55 (n=29 male individuals, n=26 female individuals) contemporary children between the ages of 6 and 14 were evaluated to measure bony greater trochanteric and the overlying cartilage cap height.

RESULTS: Intraclass correlation coefficient values for both radiographic and MRI measurements were excellent. Longitudinal radiographs demonstrated that the bony growth was largely complete by age 11 in male and female individuals. MRI measurements demonstrated that bony trochanteric and overlying cartilage cap height was maximal by age 7 in female individuals and age 8 in male individuals, while no significant difference in bony and cartilage height was appreciated with increasing age in male, female individuals or male+female individuals.

CONCLUSIONS: Combined bony and cartilaginous trochanteric growth is largely complete by age 7 in female individuals and age 8 in male individuals, with increases in the height of the trochanter beyond this age likely coming from ossification of the cartilaginous portions. As such, antegrade intramedullary nailing for closed femoral shaft fractures is reasonable in male and female individuals aged 8 years and older.

LEVEL OF EVIDENCE: Level II-retrospective study.