Abstract
Minimally invasive (MIS) techniques for deformity correction are growing in popularity. While efficacious and well-tolerated by patients, the occupational hazard resulting from dependence on X-ray technology has never previously been evaluated in the setting of deformity correction procedures. As such, the subject of radiation exposure to the patient and surgeon is of concern.
Quantify the total radiation emission with circumferential minimally invasive deformity surgery (cMIS) for adult spinal deformity (ASD), and identify factors associated with increased radiation utilization.
Retrospective analysis of prospectively collected data.
Patients with adult spinal deformity from two institutions undergoing cMIS were identified using a prospectively collected database.
The principal outcome measure was total radiation emission (mGy) across single or multistage procedures. A secondary outcome measure was total fluoroscopy time (minutes).
Inclusion criteria were: coronal cobb (CC) ≥20°, pelvic incidence – lumbar lordosis (PI-LL) >10°, sagittal vertical axis (SVA) ≥5cm, pelvic tilt (PT) ≥25°, or thoracic kyphosis (TK) ≥60°, undergoing cMIS with more ≥3 intervertebral levels fused, and use of percutaneous screws. Fluoroscopy time and mGy for all patients undergoing cMIS was abstracted from the medical records; emission data were compared to risk thresholds published by the US Nuclear Commission (5 mGy). Correlation analysis was performed to determine the association between patient and surgical factors with radiation emission and fluoroscopy time.
A total of 52 patients underwent cMIS deformity correction. Average age was 70±9 years, 41% were female with average BMI 29.4±5.4 and bone mineral density T-score of-1.6±0.8 (femur) and 1.4±0.6 (spine). Mean preoperative SVA was 9.1±12cm, with preoperative PI-LL of 14±14°. On average, patients underwent a 5±1 level fusion, with 3±1 levels of lateral interbody fusion (LLIF); 40% of cases were revision operations. Mean total fluoroscopic time was 223±155 seconds, with mean radiation emission of 179±191 mGy (33-1038mGy); the average emission dose exceeded the annual risk threshold 36 times. Radiation dose did not appear to be associated with age (p=0.81), number of levels (p=0.37), number of LLIFs (p=0.9), sagittal imbalance (p=0.09), and coronal imbalance (p=0.05). The greatest association was with spine T-score (p=0.004). Fluoroscopy time was associated with coronal imbalance (p=0.03), number of levels of fusion (p=0.001), and number of lateral interbodies placed (p<0.001).
Given the high doses of radiation exposure during MIS deformity correction, measures need to be taken to minimize exposure to the patient and surgeon. It is imperative that we consider and investigate strategies to reduce the radiation burden in the setting of treating deformity with minimally invasive techniques.
This abstract does not discuss or include any applicable devices or drugs.