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Chanbour H, Waddell WH, Vickery J, LaBarge ME, Croft AJ, Longo M, Roth SG, Hills JM, Abtahi AM, Zuckerman SL, Stephens BF. L1-pelvic angle: a convenient measurement to attain optimal deformity correction. Eur Spine J 2023; 32:4003-4011. [PMID: 37736775 DOI: 10.1007/s00586-023-07920-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/14/2023] [Accepted: 08/26/2023] [Indexed: 09/23/2023]
Abstract
PURPOSE (1) Evaluate the associations between L1-pelvic angle (L1PA) and both sagittal vertical axis (SVA) and T1-pelvic angle (T1PA), and (2) assess the clinical impact of L1PA. METHODS A single-institution retrospective cohort study was undertaken for patients undergoing adult spinal deformity (ASD) surgery from 2013 to 2017. Ideal L1PA was defined as (0.5xPelvic Incidence)-21. Pearson correlation was performed to compare L1PA, SVA, and T1PA. Univariate/multivariate regression was performed to assess the effect of L1PA on mechanical complications, controlling for age, BMI, and postoperative pelvic incidence-lumbar lordosis mismatch (PI/LL). Due to the overlapping nature of patients with pseudarthrosis and rod fracture, these patients were analyzed together. RESULTS A total of 145 patients were included. Mean preoperative L1PA, SVA, and T1PA were 15.5 ± 8.9°, 90.7 ± 66.8 mm, and 27.1 ± 13.0°, respectively. Mean postoperative L1PA, SVA, and T1PA were 15.0 ± 8.9°, 66.7 ± 52.8 mm, and 22.3 ± 11.1°, respectively. Thirty-six (24.8%) patients achieved ideal L1PA. Though the correlation was modest, preoperative L1PA was linearly correlated with preoperative SVA (r2 = 0.16, r = 0.40, 95%CI = 0.22-0.60, p < 0.001) and T1PA (r2 = 0.41, r = 0.62, 95%CI = 0.46-0.76, p < 0.001). Postoperative L1PA was linearly correlated with postoperative SVA (r2 = 0.12, r = 0.37, 95%CI = 0.18-0.56, p < 0.001) and T1PA (r2 = 0.40, r = 0.62, 95%CI = 0.45-0.74, p < 0.001). Achieving ideal L1PA ± 5° was associated with a decreased risk of rod fracture/pseudarthrosis on univariate and multivariate regression (OR = 0.33, 95%CI = 0.12-0.86, p = 0.024). No association between achieving ideal L1PA and patient-reported outcomes was observed. CONCLUSION L1PA was modestly correlated with SVA and T1PA, and achieving ideal L1PA was associated with lower rates of rod fracture/pseudarthrosis. Future studies are warranted to better define the clinical implications of achieving a normal L1PA. LEVEL OF EVIDENCE III.
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Affiliation(s)
- Hani Chanbour
- Department of Neurological Surgery, Vanderbilt University Medical Center, South Tower, 1215 21st Ave Suite #4200, Nashville, TN, 37232, USA
| | - William Hunter Waddell
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Justin Vickery
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Matthew E LaBarge
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Andrew J Croft
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael Longo
- Department of Neurological Surgery, Vanderbilt University Medical Center, South Tower, 1215 21st Ave Suite #4200, Nashville, TN, 37232, USA
| | - Steven G Roth
- Department of Neurological Surgery, Vanderbilt University Medical Center, South Tower, 1215 21st Ave Suite #4200, Nashville, TN, 37232, USA
| | - Jeffrey M Hills
- Department of Orthopedic Surgery, University of Texas, San Antonio, TX, USA
| | - Amir M Abtahi
- Department of Neurological Surgery, Vanderbilt University Medical Center, South Tower, 1215 21st Ave Suite #4200, Nashville, TN, 37232, USA
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Scott L Zuckerman
- Department of Neurological Surgery, Vanderbilt University Medical Center, South Tower, 1215 21st Ave Suite #4200, Nashville, TN, 37232, USA
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Byron F Stephens
- Department of Neurological Surgery, Vanderbilt University Medical Center, South Tower, 1215 21st Ave Suite #4200, Nashville, TN, 37232, USA.
- Department of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.
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