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Is Growing Rod Retention an Option? Outcomes After Magnetically Controlled Growing Rod "Graduation"
Zaid Elsabbagh1, Ahmed Sulieman1, Ysa Le1
1Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD.
Study Design:
Multicenter retrospective cohort.
Objective:
To compare complications, patient-reported outcomes, and radiographic measures between patients treated for early-onset scoliosis (EOS) with magnetically controlled growing rods (MCGRs) according to whether they had definitive fusion, retention of implants, or implant removal alone.
Background Data:
For patients with EOS, MCGRs enable noninvasive spinal distraction until skeletal maturity, when most undergo definitive fusion. Because MCGR expansions are more frequent than with traditional growing rods, the incidence of autofusion may differ. The long-term safety and effectiveness of implant retention is unknown.
Methods:
We included 240 patients with EOS (mean age at index surgery, 8.8 y) who completed treatment with MCGRs and had ≥2-year follow-up after definitive management. Patients were grouped by definitive management: fusion (n=225), implant retention without fusion (n=12), or implant removal alone (n=3). Demographics, radiographic parameters, Early Onset Scoliosis Questionnaire (EOSQ-24) scores, and complication rates were analyzed. P<.05 was considered significant.
Results:
Two years after definitive treatment, mean Cobb angle improved in the fusion group (54° to 42°, P<.0001), remained stable in the retention group (60°, P=.89), and worsened in the removal group (61° to 78°, P=.03). At 5 y after definitive treatment, 6 patients with retained implants maintained Cobb angle (54°) and spinal height (338 mm). At 2 years, mean T1-S1 height did not differ between fusion and retention groups (P=.61). Two years after "graduation," EOSQ-24 scores were similar across groups, except pulmonary function, which was highest in the fusion group. Chronic pain was most frequent in the removal group (2 of 3, P=.005). No patients with retained implants experienced implant-related complications.
Conclusions:
Retention of MCGRs may be considered in some high-risk patients with acceptable alignment who are poor candidates for fusion. Although short-term outcomes were promising, retention should be regarded as an exception. Long-term risks warrant further study.
Level Of Evidence:
III.
