Identification of Predictive Factors for Mechanical Complications After Adult Spinal Deformity Surgery

Abstract

Study Design. A retrospective multicenter observational study. Objective. To investigate correction surgeries that were performed in relatively aged patients in terms of mechanical complications (MCs) and their predictive factors. Summary of Background Data. The risk factors associated with MCs have not yet been well examined, especially in aged populations. Methods. We retrospectively reviewed 230 surgically treated ASD patients with an average age of 72.2 years. Twenty-eight patients with ASD caused by vertebral fractures were excluded. The minimum follow-up was 2 years. Postoperative MCs were defined as proximal junction kyphosis, distal junction kyphosis, pseudoarthrosis, rod breakage, and vertebral fractures. We divided all the ASD patients into two groups: patients with MC (the MC (+) group) and patients without MC (the MC (−) group). Radiographic parameters were evaluated before and immediately after surgery. The SRS-Schwab ASD classification and global alignment and proportion (GAP) score were also evaluated. Results. Of the 202 patients, 91 (45.0%) had MCs. The age at surgery was significantly higher in the MC (+) group than in the MC (−) group. Regarding radiographic parameters, postoperative global tilt (GT), pre- and postoperative thoracolumbar kyphosis (TLK), and postoperative thoracic kyphosis were significantly higher in the MC (+) group than in the MC (−) group. Other parameters, such as the proposed ideal alignment target of PI-LL<10, did not significantly affect MC rates. The GAP score was high in both groups and not significantly related to a higher rate of MC. Forward stepwise logistic regression indicated that the age at surgery, postoperative GT, and preoperative TLK were significant risk factors for MCs. Conclusion. Older age, higher postoperative GT, and higher pre and postoperative TLK can be risk factors for MCs. The GAP score was high in both groups and not significantly related to a higher rate of MC. Level of Evidence: 4

A Patient-specific Approach to Alignment and Proximal Junctional Kyphosis Risk Assessment in Adult Spinal Deformity Surgery

“…Several scoring and classifications systems have been developed to guide alignment goals either based on age or PI but have not generalized well in terms of preventing PJK. 20,21,46 In "The Global Alignment and Proportion (GAP) Score," the authors concluded that alignment targets should be proportional to PI. 19 Using mechanical complications as a composite outcome, the authors categorized 4 radiographic parameters using optimal cutoffs based on the outcome of interest.…”

The T4-L1-Hip Axis

“…Failure to define a thoracic alignment relative to lumbar alignment and using postural measures (eg, pelvic tilt or sagittal vertical axis) has likely contributed to the poor external validity of current alignment guidelines. [14][15][16][17][18] Our results redefine what should be considered a normal sagittal alignment and fill a critical knowledge gap. In our first aim and consistent with prior studies on sagittal balance, we found C2 tilt (also known as the Odontoid-Hip-Axis) had minimal variation and is an ideal measure of global sagittal balance.…”

“…However, PI explains only a fraction of the variation observed in normal lumbar lordosis. Furthermore, currently accepted alignment targets utilize postural measures (eg, pelvic tilt, sacral slope, or sagittal vertical axis) that are not directly modifiable in surgery, and none of the targets define a reliable method for alignment the thoracic spine, likely contributing to the poor external validity of current alignment guidelines 14–18…”

Complications in the Elderly Population Undergoing Spinal Deformity Surgery: A Systematic Review and Meta-Analysis

“…Meta-analyses of 2 studies reported no relationship between uppermost instrumented vertebrae (UIV) above T6, UIV below T6, lower instrumented vertebrae (LIV) to the sacrum and relationship to the development of implant-related complications (data not shown). 19,20 Individually reported independent risk factors for implant-related complications included increased age at surgery, greater postoperative global tilt, greater preoperative thoracolumbar kyphosis, and pedicle subtraction osteotomy at S1. 19,21 Risk Factors for PJK…”

“…19,20 Individually reported independent risk factors for implant-related complications included increased age at surgery, greater postoperative global tilt, greater preoperative thoracolumbar kyphosis, and pedicle subtraction osteotomy at S1. 19,21 Risk Factors for PJK…”