Limb Lengthening in Russell-Silver Syndrome: An Update Confirming Safe and Speedy Healing

Introduction: Russell-Silver syndrome (RSS) is a unique cause of syndromic, and often severe, limb length discrepancy (LLD). RSS causes growth retardation both in utero and postnatally, with asymmetry in limb length more noticeable as growth progresses throughout childhood and adolescent. We aim to present the largest cohort in the literature on limb lengthening in patients with RSS and to validate previous literature supporting faster bony consolidation in these patients with more robust data. We further aim to establish differences in healing within this cohort based on age, sex, segment lengthened, or type of lengthening procedure performed, to help refine patient expectations and guide practitioners in treating this population. Methods: This was a retrospective study of patients with a diagnosis of RSS who underwent a limb lengthening procedure for the purpose of limb equalization. They were compared with a historic control group of patients who underwent limb lengthening for LLD of a non-RSS etiology. The primary outcome measure was bone healing index (BHI). Results: The RSS group consisted of 24 patients with 29 segments lengthened, and was compared with a historic control group consisting of 20 patients with 22 segments lengthened (Goldman). Patients with RSS had a significantly lower BHI, and therefore faster healing of their lengthening site, than their non-RSS peers (P=0.02). Within the RSS cohort, we did not detect a difference in BHI based on intervention type or sex, but we did find a trend toward faster healing in femurs over tibiae (P=0.08), and established that younger patients tended toward lower BHIs (P<0.01). Conclusions: Our results confirmed with more robust data the prior finding that patients with RSS may undergo limb lengthening procedures at least as safely as their non-RSS counterparts, and with even faster bony consolidation, especially in younger patients. We hypothesize that concurrent treatment with growth hormone supplementation may contribute to this finding, although further study is necessary. This is the largest cohort of RSS patients treated with limb lengthening for LLD reported in the literature, and these findings will help to guide surgeon decision-making when treating this unique population. Level of Evidence: Level III - retrospective comparative study.