The evolving stall rate of magnetically controlled growing rods beyond 2 years follow-up

• Published in: Spine deformity 2023-03, Vol.11 (2), p.487-493
• Main Authors: Shaw, K. Aaron, Bassett, Paul, Ramo, Brandon A., McClung, Anna, Thornberg, David, Jamnik, Adam, Jo, Chan-Hee, Johnston, Charlie E., McIntosh, Amy L.
• Format: Article
• Language: English
• Subjects: Case Series; Child; Child, Preschool; Female; Follow-Up Studies; Humans; Male; Medicine; Medicine & Public Health; Orthopedic Procedures; Orthopedics; Prostheses and Implants; Retrospective Studies; Scoliosis - surgery
• ISSN: 2212-134X; 2212-1358
• DOI: 10.1007/s43390-022-00622-5

Purpose Magnetically controlled growing rods (MCGR) have become the dominant distraction-based implant for the treatment of early onset scoliosis (EOS). Recent studies, however, have demonstrated rising rates of implant failure beyond short-term follow-up. We sought to evaluate a single-center experience with MCGR for the treatment of EOS to define the rate of MCGR failure to lengthen, termed implant stall, over time. Methods A single-center, retrospective review was conducted identifying children with EOS undergoing primary MCGR implantation. The primary endpoint was the occurrence of implant stalling, defined as a failure of the MCGR to lengthen on three consecutive attempted lengthening sessions with minimum of 2 years follow-up. Clinical and radiographic variables were collected and compared between lengthening and stalled MCGRs. A Kaplan–Meier survival analysis was conducted to assess implant stalling over time. Results A total of 48 children met inclusion criteria (mean age 6.3 ± 1.8 years, 64.6% female). After a mean 56.9 months ( range of 27 to 90 months ) follow-up, 25 (48%) of children experienced implant stalling at a mean of 26.0 ± 14.1 months post-implantation. Kaplan–Meier survival analysis demonstrated that only 50% of MCGR continue to successfully lengthen at 2 years post-implantation, decreasing to