• Francis Lovecchio, Renaud Lafage, Han Jo Kim, Shay Bess, Christopher Ames, Munish Gupta, Peter Passias, Eric Klineberg, Gregory Mundis, Douglas Burton, Justin S Smith, Christopher Shaffrey, Frank Schwab, Virginie Lafage, and International Spine Study Group.
• Department of Spine Surgery, Hospital for Special Surgery, New York, NY.
• Spine. 2024 Feb 1; 49 (3): 157164157-164.

Study DesignMulticenter retrospective cohort study.ObjectiveTo investigate risk factors for loss of correction within the instrumented lumbar spine after adult spinal deformity surgery.Summary Of Background DataThe sustainability of adult spinal deformity surgery remains a health care challenge. Malalignment is a major reason for revision surgery.Patients And MethodsA total of 321 patients who underwent fusion of the lumbar spine (≥5 levels, LIV pelvis) with a revision-free follow-up of ≥3 years were identified. Patients were stratified by a change in pelvic incidence-lumbar lordosis from 6 weeks to 3 years postoperative as "maintained" versus "loss" >5°. Those with instrumentation failure (broken rod, screw pullout, etc .) were excluded before comparisons. Demographics, surgical data, and radiographic alignment were compared. Repeated measure analysis of variance was performed to evaluate the maintenance of the correction for L1-L4 and L4-S1. Multivariate logistic regression was conducted to identify independent surgical predictors of correction loss.ResultsThe cohort had a mean age of 64 years, a mean Body Mass Index of 28 kg/m 2 , and 80% females. Eighty-two patients (25.5%) lost >5° of pelvic incidence-lumbar lordosis correction (mean loss 10±5°). After the exclusion of patients with instrumentation failure, 52 losses were compared with 222 maintained. Demographics, osteotomies, 3CO, interbody fusion, use of bone morphogenetic protein, rod material, rod diameter, and fusion length were not significantly different. L1-S1 screw orientation angle was 1.3 ± 4.1 from early postoperative to 3 years ( P = 0.031), but not appreciably different at L4-S1 (-0.1 ± 2.9 P = 0.97). Lack of a supplemental rod (odds ratio: 4.0, P = 0.005) and fusion length (odds ratio 2.2, P = 0.004) were associated with loss of correction.ConclusionsApproximately, a quarter of revision-free patients lose an average of 10° of their 6-week correction by 3 years. Lordosis is lost proximally through the instrumentation ( i.e. tulip/shank angle shifts and/or rod bending). The use of supplemental rods and avoiding sagittal overcorrection may help mitigate this loss.Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.

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