Bone Age in Girls Aged 5.5 Years — Greulich-Pyle Hand and Wrist X-Ray Reference
Bone age assessment using the Greulich-Pyle (GP) atlas involves comparing a left-hand and wrist radiograph to standardized reference plates to estimate skeletal maturity. In girls aged 5.5 years, this evaluation helps clinicians identify deviations from expected skeletal development that may signal endocrine disorders, growth hormone deficiency, or constitutional growth variants. Accurate bone age determination is also valuable in forensic age estimation and in planning interventions for conditions such as precocious puberty.
Expected Ossification Centers and Skeletal Findings
By 5.5 years of age in girls, the majority of carpal ossification centers are typically visible. The capitate and hamate ossify very early (around 3 and 6 months, respectively) and are well established by this age. The triquetral (typically appearing around 2–3 years) and lunate (around 3–4 years) should both be present and showing progressive definition. The scaphoid, trapezium, and trapezoid typically appear between 4 and 6 years, and at 5.5 years in girls these centers are expected to be present or emerging, reflecting the relative advancement of female skeletal maturation.
The distal radial epiphysis is well ossified by this age, having typically appeared around 1 year. The distal ulnar epiphysis usually appears between 5 and 7 years, so its presence or early emergence may be noted at this age in girls. Metacarpal and proximal, middle, and distal phalangeal epiphyses are all present and show progressive widening and sharpening of their margins. The pisiform is not yet expected at this age, as it typically appears around 9–12 years in girls.
- Capitate and hamate: well ossified
- Triquetral and lunate: present and maturing
- Scaphoid, trapezium, trapezoid: typically present or emerging by 5–6 years in girls
- Distal radial epiphysis: well formed
- Distal ulnar epiphysis: may be appearing
- Pisiform and thumb sesamoid: not yet expected
Clinical Pearls
The standard deviation for GP bone age at this age is approximately ±1 year; a bone age more than 2 SD above or below chronological age warrants further evaluation. Girls are skeletally ahead of boys by approximately 6–12 months at this age, so male reference plates should not be applied. An advanced bone age in a 5.5-year-old girl raises concern for precocious puberty, congenital adrenal hyperplasia, or exogenous androgen/estrogen exposure. A delayed bone age may suggest growth hormone deficiency, hypothyroidism, or constitutional delay of growth and puberty. A key interpretive pitfall is over-reliance on a single ossification center; the overall pattern of carpal and epiphyseal maturation across the hand should guide the assessment rather than any isolated finding.
Reference: Greulich WW, Pyle SI. Radiographic Atlas of Skeletal Development of the Hand and Wrist. 2nd ed. Stanford University Press, 1959.
