Outcome of distraction-based growing rods at graduation: a comparison of traditional growing rods and magnetically controlled growing rods

Jwalant Mehta; Suken Shah; Harry Hothi; Martina Tognini; Adrian Gardner; Charles E Johnston; Robert Murphy; George Thompson; Paul Sponseller; John Emans; Francisco Javier-Grueso; Peter Strum; Pediatric Spine Study Group

doi:10.1007/s43390-024-00969-x

Outcome of distraction-based growing rods at graduation: a comparison of traditional growing rods and magnetically controlled growing rods

Spine Deform. 2024 Sep 23. doi: 10.1007/s43390-024-00969-x. Online ahead of print.

Authors

Collaborators

Pediatric Spine Study Group:
Jwalant Mehta, Suken Shah, Adrian Gardner, Charles E Johnston, Robert Murphy, George Thompson, Paul Sponseller, John Emans, Francisco Javier-Grueso, Peter Strum

Affiliations

¹ Royal Orthopaedic Hospital, Spinal Unit, Birmingham, England. Jsm@mehtaspine.co.uk.
² Nemours Childrens' Hospital, Delaware, Wilmington, DE, 19803, USA.
³ Mechanical Engineering Department, University College London, London, England.
⁴ Royal Orthopaedic Hospital, Spinal Unit, Birmingham, England.
⁵ Texas Scottish Rite Hospital, Dallas, TX, USA.
⁶ Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
⁷ Rainbow Babies and Childrens' Hospital, Case Western Reserve University, Cleveland, OH, USA.
⁸ Johns Hopkins School of Medicine, Baltimore, MD, USA.
⁹ Boston Childrens' Hospital, Boston, MA, USA.
¹⁰ Perdro Rico, Madrid, Spain.
¹¹ Cincinnati Childrens Hospital, Cincinnati, OH, USA.

PMID: 39313723
DOI: 10.1007/s43390-024-00969-x

Abstract

Introduction: Distraction-based growing rods have been considered as an alternative surgical option for the operative treatment of EOS. TGR has been challenged by MCGR, which is reported to have the advantage of non-invasive lengthening with fewer planned returns to theatre. This study explores the radiographic outcomes, Unplanned Returns to the Operating Room (UPROR) and complication profile of both the procedures at the end of the planned growing rod treatment with either TGR or MCGR.

Methods: We included all the EOS cases from the PSSG database that underwent either TGR or MCGR with spine-based proximal anchors, followed up to the time of graduation. Any crossover or hybrid procedures were excluded. 549 patients (409 TGR and 140 MCGR) were eligible for review. We measured the coronal curve magnitude, Kyphosis, T1-T12, T1-S1 and L1-S1 lengths at 4 time points (before and after the index surgery and before and after the definitive surgery).

Results: The TGR group were slightly younger at the time of the index procedure (7 years for TGR vs. 8.5 years for MCGR, p < 0.001). We noted an improvement in all radiological parameters after the growing rod implantation. The spinal lengths increased through the lengthening period, while the coronal curve magnitude and the kyphosis increased. The kyphosis normalized following the final fusion, the coronal curve magnitude reduced further with a further increase in spinal lengths. The final follow-up from the time of the index implantation to the definitive surgery was 5.1 years (IQR 3.8) in TGR and 3.5 years (IQR 1.65) in the MCGR groups. The total number of complications was fewer in the MCGR group. The overall risk of UPROR was lower in the MCGR group and implant breakage was less in the MCGR group by 4.7 times.

Conclusions: This study confirms the equivalence of both the distraction-based growing rods systems from the radiological stand-point, during the lengthening phase and at the time of the definitive surgery. The TGR was more kyphogenic during the lengthening period. The complications and UPROR were fewer in the MCGR groups.

Keywords: Distraction-based growing rods; Graduates of growing rods; Magnetic rods; Traditional growing rods; Unplanned returnes to OR.