This anatomic study of 180 children's humeri from the Hamann-Todd skeletal collection asks when the humeral head derotates from marked fetal retroversion to adult values. Using dry-bone measurements across ages 4 months to 19 years, the author maps the developmental timeline no prior study had documented in the shoulder.
When you operate on a young shoulder, the retroversion is a moving target, not the fixed 25° to 30° you assume in adults.
The head sits in high retroversion early and derotates through childhood. Carry the mental model that derotation is fast early and mostly done by age 8, then trickles on until the radial groove forms around 16. That radial groove is your anatomic tidemark that adult rotation is complete.
This matters for arthroplasty and for rotational osteotomy in instability surgery, where you must reproduce or deliberately alter version. Hold this alongside the hip: femoral anteversion and humeral retroversion derotate on comparable timelines but in opposite directions, a clean way to remember both.
One appraisal caveat: these are dry-bone measurements, and the author notes his angles run higher than radiographic or CT values because defining the true head axis is hard. Treat the absolute numbers as anthropologic and the developmental timeline as the takeaway.
This anatomic study of 180 children's humeri from the Hamann-Todd skeletal collection asks when the humeral head derotates from marked fetal retroversion to adult values. Using dry-bone measurements across ages 4 months to 19 years, the author maps the developmental timeline no prior study had documented in the shoulder.
When you operate on a young shoulder, the retroversion is a moving target, not the fixed 25° to 30° you assume in adults.
The head sits in high retroversion early and derotates through childhood. Carry the mental model that derotation is fast early and mostly done by age 8, then trickles on until the radial groove forms around 16. That radial groove is your anatomic tidemark that adult rotation is complete.
This matters for arthroplasty and for rotational osteotomy in instability surgery, where you must reproduce or deliberately alter version. Hold this alongside the hip: femoral anteversion and humeral retroversion derotate on comparable timelines but in opposite directions, a clean way to remember both.
One appraisal caveat: these are dry-bone measurements, and the author notes his angles run higher than radiographic or CT values because defining the true head axis is hard. Treat the absolute numbers as anthropologic and the developmental timeline as the takeaway.