Lightning Podiums: Adult Spinal Deformity - Room 801A

Presented by: P. Passias

Author(s):

V. Fiere(1), S. Fuentes(2), E. Burger(3), T. Raabe(4), P.G. Passias(5), C. Kleck(3), T. Protopsaltis(5), A. Faure(2), P. Tropiano(2), A. Vaccaro(6), B. Blondel(2)

(1) Centre Orthopédique Paul Santy, Lyon, France
(2) Hôpital de la Timone, Chirurgie Orthopédique, Traumatique et Vertébrale, Marseille, France
(3) University of Colorado Anschutz, Medical Campus, Aurora, CO, United States
(4) East Texas Medical Center, Houston, TX, United States
(5) NYU Langone Orthopedic Hospital, New York, NY, United States
(6) Rothman Institute, Thomas Jefferson University, Philadelphia, PA, United States

Abstract

Introduction: Adult Spinal Deformity (ASD) is becoming increasingly prevalent as the population ages. Its negative impact on quality of life often necessitates surgical intervention, often associated with a high level of complications. Within 2 years postoperatively, the overall revision rate can reach up to 16.5% leading to additional charges, supplemental risks for infection and negative impact on final treatment success. Implant-related complications are predominant. Overall rod breakage incidence is reported as high as 14.9% of patients following ASD surgery. When a pedicle subtraction osteotomy (PSO) is performed, the rod fracture rate increases up to 22% within 10 months after surgery. Risk factors for rod breakage include rod diameter and material, excessive rod contouring (>60%) and notches introduced by rod-benders during the contouring process, or through connections with other implants including tulip screws, dominos and hooks. The recent development of patient-specific rods (PSR) (UNiD, Medicrea France), using Surgimap Software (Nemaris Inc, NY USA) offers a solution that may reduce the risk factors above. PSRs are manufactured with a soft and regular curve compared to those manually bent. PSRs are delivered ready to implant without additional contouring required in the operating room, eliminating surgical time used to manually bend rods and preventing notches. This new family of implants was expected to reduce the rod breakage rate and associated surgical revisions. This paper aims to quantify PSR failures compared to conventional rods.

Materials and Methods: A prospective anonymized adverse event database was generated by the manufacturer through a European clinical trial (NCT02926404), and a post-market survey. Between September 2013 and June 2017, 1515 surgeries were performed including 1031 (68%) adult cases. Among adults, 889 were implanted for ASD (>4 levels) with an average of 10 levels instrumented. The cohort finally includes 453 ASD patients implanted for more than 1 year.

Results: Ten patients reported 11 rod breakages (2.2%). One patient experienced two successive breakages as he was unwilling to undergo the supplemental anterior fixation previously planned. The 10 patients presenting rod fracture have a mean of 12 levels instrumented. In terms of 3-column osteotomies, 2 underwent a vertebral corpectomy (1 double-level at L3L4 and one single-level at L2), and 6 underwent one PSO (L3:3; L2:2; L4:1). Regarding rod material, 2 surgeries were performed with Cobalt Chromium 5.5 diameter rods, 4 with Cobalt Chromium 6.0 diameter rods, and 5 with Titanium 6.0 diameter rods. To date 10 out 11 rod failures were revised. PSOs were performed 127 surgeries of which 6 were followed by a rod failure, always occurring around the PSO site, leading to an overall rod breakage of 4.7% when PSO is performed.

Conclusion: The use of PSR in spinal surgeries seems to reduce rod breakage incidence when compared to literature. Despite the short follow-up period, this is encouraging, especially considering surgeons often utilized PSR in their complex surgeries. This demonstrates that use of PSR with absence of manual rod contouring can have a major impact on rod failure. This result has now to confirmed over longer-term follow-up.