Four-Year Follow-Up of the World’s First Pediatric Bilateral Hand-Forearm Transplants: Do They Grow as Expected?

Background: In 2015, the first bilateral pediatric hand-forearm transplant was performed in an 8-year-old boy. The growth rate of the transplanted upper extremities was unknown at the time. Methods: Forearm and hand radiographs were obtained annually. Radius and ulna measurements were performed by multiple coauthors and mathematically normalized using a standardized methodology. The Greulich and Pyle atlas was used to estimate hand bone age. Results: From July of 2015 to July of 2019, unadjusted bone length (metaphysis to metaphysis) increased 38.8 and 39.6 mm for the left radius and ulna, and 39.5 and 35.8 mm for the right radius and ulna, respectively. Distal physes of the donor limbs increasingly contributed to overall bone length relative to proximal physes. Normalized growth between the two limbs was statistically similar. At each annual follow-up, the bone age increased by 1 year. Conclusions: Successful pediatric hand-forearm transplantation offers the advantage of growth similar to that of nontransplanted pediatric patients. The transplanted distal physes contributes more to the overall growth, paralleling normal pediatric growth patterns. Chronologic age parallels the increase in bone age.