A Korean research team has, for the first time in the world, identified that in children with congenital hemihyperplasia and hemihypoplasia—conditions in which one side of the body grows abnormally larger or smaller—not only the lengths of the limbs but also the rate at which bones mature differ between the two sides.
In particular, the longer limb showed faster bone growth, a finding expected to serve as an important benchmark for determining the timing of customized growth plate surgery for each child.
A team led by Shin Chang-ho, a pediatric orthopedic surgeon at Seoul National University Hospital (clinical instructor Lee Won-ik), said on the 28th that an analysis of 118 children with congenital hemihyperplasia and hemihypoplasia confirmed a difference in bone age between the two sides of the limbs. The study was published in the latest issue of the Journal of Children's Orthopaedics.
Congenital hemihyperplasia and hemihypoplasia are rare diseases in which one side of the body grows excessively larger or smaller than the opposite side. If limb length discrepancy worsens, it can lead to gait disturbance, scoliosis, and degenerative joint changes. Representative causative conditions include Beckwith-Wiedemann syndrome and Silver-RUSSELL syndrome.
To correct a child's leg length discrepancy, growth plate surgery is performed, and measuring bone age—which predicts remaining growth—is essential to determine the exact timing of surgery. However, despite clinical suspicion that bone ages might differ between sides, the lack of objective evidence led to decisions based only on one side's bone age.
The team studied 118 children treated at Seoul National University Children's Hospital from Jan. 2000 to Sept. 2023. The cohort included ▲34 with Beckwith-Wiedemann syndrome ▲14 with Silver-RUSSELL syndrome ▲14 with PIK3CA-related overgrowth syndrome ▲56 with idiopathic cases of unknown cause.
The researchers compared and analyzed bone age in both limbs using the Korean standard bone age chart and the modified Fels method. The modified Fels method can precisely calculate bone maturity to within months.
Notably, instead of looking only at hand bone age as before, the team also analyzed bone age at the knee, where growth plate surgery is actually performed. This reflects that about 65% of leg growth occurs around the knee.
The analysis found no clear difference when simply comparing left and right, but a distinct difference emerged when comparing the "longer side" with the "shorter side." Across all children, the bone age of the longer arm was on average 1.2 months ahead of the shorter side.
The difference was particularly pronounced in children with Beckwith-Wiedemann syndrome. The bone age of the longer leg was on average 7.1 months greater than the shorter side, and the longer arm was also on average 3.2 months ahead. The researchers said this phenomenon is directly related to "overgrowth" due to the disease itself rather than a simple left-right difference. In contrast, no significant differences were observed in other disease groups, such as Silver-RUSSELL syndrome.
The team expects the study to improve the precision of growth plate surgery. Calculating remaining growth based only on one side's bone age, as in the past, risks overestimating final leg length discrepancy, but reflecting that the longer side's bone matures faster could reduce overcorrection and the possibility of reoperation.
Shin Chang-ho, a pediatric orthopedic surgeon at Seoul National University Hospital, said, "In treating children with congenital hemihyperplasia and hemihypoplasia, we should assess not only the simple length difference but also which side's bone is growing faster," and added, "We hope this study will serve as a basis for patient-specific growth prediction and surgical planning."
This study was conducted with support from the Pediatric Cancer and Rare Disease Support Project Group.
References
Journal of Children's Orthopaedics (2026), DOI: https://doi.org/10.1177/18632521261434091