Patients with rare disorders that cause one side of the body to grow larger than the other show differences not only in limb length but also in the speed at which their bones mature, Korean medical researchers have found for the first time. By demonstrating that bones on the longer side may complete growth earlier, the findings provide a basis for more precisely determining the timing of corrective surgery.
Seoul National University Hospital announced Friday that a team led by Shin Chang-ho, professor of pediatric orthopedics, analyzed bone age differences between limbs in 118 children with congenital hemihyperplasia and hemihypoplasia.
Congenital hemihyperplasia and hemihypoplasia are conditions in which one side of the body grows noticeably larger or smaller than the other. Genetic abnormalities such as Beckwith-Wiedemann syndrome or Silver-Russell syndrome are known to be the main causes. When the difference in limb length becomes severe, the body's balance is disrupted, potentially leading to serious complications including gait disorders, scoliosis and degenerative joint changes, requiring surgical treatment. Growth plate surgery is commonly performed to correct limb length discrepancies. In clinical practice, questions had persistently been raised about whether the bone ages on the two sides of these patients might differ, but in the absence of objective data to verify this, remaining growth had been predicted based on the bone age of one side.
The research team set out to test the hypothesis that, given the nature of the disease, there could be a difference in maturation speed itself between the two sides. The team enrolled 118 children who had been examined at Seoul National University Children's Hospital between January 2000 and September 2023 for conditions including Beckwith-Wiedemann syndrome, Silver-Russell syndrome and PIK3CA-related overgrowth syndrome. The researchers compared bone age using the Korean standard skeletal age chart and the Fels system, which assesses skeletal maturity based on X-rays of the hand, wrist and knee in children. Considering that about 65% of leg growth occurs around the knee, the team enhanced predictive accuracy by additionally analyzing knee bone age rather than relying solely on hand bone age, as had been done previously.
The results showed that across the entire patient group, the bone age of the longer arm was on average 1.2 months ahead of that of the shorter side. In particular, among 34 patients with Beckwith-Wiedemann syndrome, the bone age of the longer leg and arm was on average 7.1 months and 3.2 months greater, respectively, showing the most pronounced growth asymmetry. According to the research team's interpretation, this suggests that the difference in bone growth speed is not simply a matter of anatomical direction (left or right) but is directly linked to the body's "overgrowth" caused by the disease. In contrast, no significant differences were observed in other disease groups such as Silver-Russell syndrome.
The research team expects the findings to substantially improve the precision of limb-length correction surgery. Rather than predicting remaining growth based on the bone age of only one side as before, planning surgical timing while considering the characteristic that bones on the longer side grow faster can significantly reduce the risk of unnecessary overcorrection or reoperation.
"When treating limb length discrepancies in patients with congenital hemihyperplasia and hemihypoplasia, it is necessary to evaluate not just length differences, but also which side's bones are growing faster," Shin said. "We hope this study will provide practical evidence for predicting growth and establishing surgical plans for these children."
The study was supported by the Pediatric Cancer and Rare Disease Support Project and was published in a recent issue of the international Journal of Children's Orthopaedics.
