P109. Precontoured rods in achieving planned regional and global alignment: a lot of planning but does it matter in adult spinal deformity? A multicentered study

BACKGROUND CONTEXT The aim of complex spinal deformity correction is to restore both sagittal and coronal balance of the spine. Many studies have shown adverse clinical outcomes related to under and over corrected sagittal and coronal deformities. With proper surgical planning, such under and over correction can be mitigated and patient outcomes can be improved and other complications, such as PJK, can be minimized. PURPOSE Precontoured rod instrumentation for adult spinal deformity (ASD) can accurately achieve planned alignment parameters in the sagittal and coronal planes. STUDY DESIGN/SETTING Multicentered cohort. PATIENT SAMPLE Adult patients (age 18) undergoing instrumentation with pre-contoured rods from 2018-2021. OUTCOME MEASURES Sagittal parameters included C2 slope, cervical lordosis (CL), C2 pelvic angle (CPA), cervicothoracic pelvic angle (CTPA), lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), sacral slope (SS), sagittal vertical axis (SVA), T1 spinopelvic inclination (T1SPI), T1 slope, T1 slope-CL (T1 slope-CL), thoracic kyphosis (TK), T1 pelvic angle (TPA), C2-C7 SVA (cSVA). Coronal parameters included major coronal curve (MCC) and coronal balance (CVA). METHODS A multicenter cohort of adult patients (age 18) undergoing instrumentation with pre-contoured rods was reviewed from 2018-2021. RESULTS A total of 289 patients were included in the study (mean age: 61.3±13.5yrs, 156 (54%) female, mean total instrumented levels: 8.2±5.0). At 6mo followup, the preoperative plan accurately predicted CL, MCC, and CVA with 71 (62.8%), 33 (68.6%) and 37 (69.8%) patients meeting acceptable criteria (ie, difference of ≤5° or ≤10mm), respectively. However, by 2yrs, accuracy in predicting regional parameters improved including LL (mean error: -3.9±10.2°; P=0.064), PI-LL (-2±9.1°; P=0.265), PT (0.05±5.7°; P=0.968), TK (-6.0±11.3°; 0.059). Similarly, mean errors for global parameters including T1SPI (-1.8±4.2°; 0.126), TPA (-1.8±5.7°, 0.233) and CVA (-1.4±16.8mm, 0.874) were low and statistically insignificant. Although mean differences between plan and 2yr postop for CPA, CTPA, SVA and cSVA were statistically significant, the mean error was 20mm, respectively proving a small clinical difference. CONCLUSIONS In the first and largest, multicenter study with 2-year followup evaluating use of pre-contoured rods, we found high accuracy for both coronal and sagittal correction (regionally and globally) in predicting postoperative alignment parameters. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. The aim of complex spinal deformity correction is to restore both sagittal and coronal balance of the spine. Many studies have shown adverse clinical outcomes related to under and over corrected sagittal and coronal deformities. With proper surgical planning, such under and over correction can be mitigated and patient outcomes can be improved and other complications, such as PJK, can be minimized. Precontoured rod instrumentation for adult spinal deformity (ASD) can accurately achieve planned alignment parameters in the sagittal and coronal planes. Multicentered cohort. Adult patients (age 18) undergoing instrumentation with pre-contoured rods from 2018-2021. Sagittal parameters included C2 slope, cervical lordosis (CL), C2 pelvic angle (CPA), cervicothoracic pelvic angle (CTPA), lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), sacral slope (SS), sagittal vertical axis (SVA), T1 spinopelvic inclination (T1SPI), T1 slope, T1 slope-CL (T1 slope-CL), thoracic kyphosis (TK), T1 pelvic angle (TPA), C2-C7 SVA (cSVA). Coronal parameters included major coronal curve (MCC) and coronal balance (CVA). A multicenter cohort of adult patients (age 18) undergoing instrumentation with pre-contoured rods was reviewed from 2018-2021. A total of 289 patients were included in the study (mean age: 61.3±13.5yrs, 156 (54%) female, mean total instrumented levels: 8.2±5.0). At 6mo followup, the preoperative plan accurately predicted CL, MCC, and CVA with 71 (62.8%), 33 (68.6%) and 37 (69.8%) patients meeting acceptable criteria (ie, difference of ≤5° or ≤10mm), respectively. However, by 2yrs, accuracy in predicting regional parameters improved including LL (mean error: -3.9±10.2°; P=0.064), PI-LL (-2±9.1°; P=0.265), PT (0.05±5.7°; P=0.968), TK (-6.0±11.3°; 0.059). Similarly, mean errors for global parameters including T1SPI (-1.8±4.2°; 0.126), TPA (-1.8±5.7°, 0.233) and CVA (-1.4±16.8mm, 0.874) were low and statistically insignificant. Although mean differences between plan and 2yr postop for CPA, CTPA, SVA and cSVA were statistically significant, the mean error was 20mm, respectively proving a small clinical difference. In the first and largest, multicenter study with 2-year followup evaluating use of pre-contoured rods, we found high accuracy for both coronal and sagittal correction (regionally and globally) in predicting postoperative alignment parameters.