Evaluation of simultaneous bilateral femoral distraction osteogenesis with antegrade intramedullary lengthening nails in achondroplasia with rhizomelic short stature: a retrospective study of 15 patients with a minimum follow-up of 2 years

Abstract

Background and purpose: Bilateral femoral distraction osteogenesis in patients with achondroplasia is insufficiently reported. We aimed to perform the first study that exclusively analyzed simultaneous bilateral femoral distraction osteogenesis with motorized intramedullary lengthening nails via an antegrade approach in patients with achondroplasia focused on reliability, accuracy, precision, and the evolving complications.Patients and methods: In this retrospective singlecenter study we analyzed patients with achondroplasia who underwent simultaneous bilateral femoral lengthening with antegrade intramedullary lengthening nails between October 2014 and April 2019. 15 patients (30 femoral segments) of median age 14 years (interquartile range [IQR] 12–15) were available for analysis. The median follow-up was 29 months (IQR 27–37) after nail implantation. Results: The median distraction length per segment was 49 mm (IQR 47–51) with a median distraction index of 1.0 mm/day (IQR 0.9–1.0), and a median consolidation index of 20 days/cm (IQR 17–23). Reliability of the lengthening nails was 97% and their calculated accuracy and precision were 96% and 95%, respectively. The most common complication was temporary restriction of knee range of motion during distraction in 10 of 30 of the lengthened segments. 1 patient was treated with 2 unplanned additional surgeries due to premature consolidation.Conclusion: The method is reliable and accurate with few complications.

What’s new in pediatric lower limb reconstruction?

“…The general trend toward the application of intramedullary lengthening nails as an alternative to external fixators for distraction osteogenesis also accounts for patients with achondroplasia. Recently, reliable results for exclusively performed simultaneous bilateral femoral lengthening with intramedullary lengthening nails were reported, 54 whereas other studies evaluating the outcome of short stature lengthening using external and internal devices demonstrated that intramedullary lengthening nails can safely be applied for bilateral femoral and/or tibial lengthening. 55 , 56 Usually, intramedullary lengthening nails are applied following several consecutive fixator-controlled lengthening procedures as part of a multi-stage treatment concept for extensive lower limb lengthening.…”

“… 55 , 56 Usually, intramedullary lengthening nails are applied following several consecutive fixator-controlled lengthening procedures as part of a multi-stage treatment concept for extensive lower limb lengthening. 54 – 56 Of course, in younger patients with bone dimensions too small for intramedullary devices, external fixators continue to be the gold standard for distraction osteogenesis. 54 – 56 It remains unclear if lengthening plates will contemplate the armamentarium of devices applicable for lengthening in patients with open growth plates in future.…”

“… 54 – 56 Of course, in younger patients with bone dimensions too small for intramedullary devices, external fixators continue to be the gold standard for distraction osteogenesis. 54 – 56 It remains unclear if lengthening plates will contemplate the armamentarium of devices applicable for lengthening in patients with open growth plates in future. 57 In contrast to femoral lengthening with internal devices, Rovira Martí et al 57 confirmed that prophylactic intramedullary rodding should be considered to prevent regenerate re-fracture after femoral lengthening using external fixators in patients with achondroplasia.…”