The potential of spring distraction to dynamically correct complex spinal deformities in the growing child

Sebastiaan P J Wijdicks,Justin V C Lemans,Gijsbertus J Verkerke,Herke Jan Noordmans,Moyo C Kruyt,René M Castelein

doi:10.1007/s00586-020-06612-3

Abstract

PurposeCurrent treatment of progressive early onset scoliosis involves growth-friendly instrumentation if conservative treatment fails. These implants guide growth by passive sliding or repeated lengthenings. None of these techniques provide dynamic correction after implantation. We developed the spring distraction system (SDS), by using one or multiple compressed springs positioned around a standard sliding rod, to provide active continuous distraction of the spine to stimulate growth and further correction. The purpose of this study was to determine feasibility and proof of concept of the SDS.MethodsWe developed a versatile, dynamic spring distraction system for patients who would benefit from active continuous distraction. This prospective case series evaluates four patients with exceptional and progressive congenital spine deformities.ResultsFour patients had a mean age of 6.8 years at surgery with a mean follow-up of 36 months (range 25–45). The mean progressive thoracic lordosis, which was the reason for initiating surgical treatment in two patients, changed from 32° lordosis preoperatively to 1° kyphosis post-operatively. During follow-up, this further improved to 32° thoracic kyphosis. In the two other patients, with cervicothorcacic scoliosis, the main coronal curve improved from 79° pre-operatively to 56° post-operatively and further improved to 42°. The mean T1-S1 spine growth during follow-up for all patients was 1.3 cm/year. There was one reoperation because of skin problems and no device-failures.ConclusionThese early results show the feasibility and the proof of concept of spring-based distraction as a dynamic growth-enhancing system with the potential of further correction of the deformity after implantation.

Highlights

Onset spinal deformities can progress severely during growth
Because we expected all currently available growthfriendly systems to fail for this specific case, we developed the posterior spring distraction system which we implanted bilaterally
There were no deep infections, rod fractures, spring fractures or screw pull-outs in all 4 patients. This case series has shown that the feasibility of the spring distraction system (SDS) as a relatively easy and low invasive option for complex congenital deformities

Summary

Introduction

Onset spinal deformities can progress severely during growth. Especially in young children, this may result in thoracic insufficiency syndrome or untreatable spinal malformations [1]. Current growth-friendly systems can potentially stop curve progression while allowing the spine to maintain growth [3] Some of these implants guide the reduced deformity by passive sliding, e.g., Shilla or Luque trolley techniques [4, 5]. Implants that follow growth with repeated lengthenings are used, e.g., traditional growing rods (TGR), vertical expandable prosthetic titanium rib (VEPTR) or magnetically controlled growing rods (MCGR) [1, 2, 6] These techniques have dramatically improved our ability to treat early onset spinal deformities, some aspects can still be addressed to improve surgical outcomes: First, none of these systems dynamically stimulate growth and further reduction of the affected spinal segments. Instrumentation failures are frequently observed [10, 11]

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