The odontoid-CSVL distance in a global population of asymptomatic volunteers: normative values and implications for spinal coronal alignment

Coronal alignment in normal individuals and moderate scoliosis: Normative values, variation with age and comparison with sagittal alignment

Introduction

Global coronal alignment is mainly assessed by C7 plumbline and central sacral vertical line (CSVL), pelvic obliquity and shoulder alignment. A detailed analysis is mandatory when treating spinal deformity. It remains unclear to what extent mild scoliosis influences global coronal alignment.

Research question

The objective was to define a comprehensive set of coronal alignment parameters and to investigate differences between individuals without spinal deformity and with mild scoliosis. The relationship between coronal and sagittal alignment and the influence of age were studied.

Methods

Radiographs of 236 normal individuals (Group N) and 140 patients with scoliosis <35° (Group S) were prospectively collected. Coronal parameters were femoral head distance and angle, pelvic obliquity, Maloney angle, L4 and L5 inclinations, coronal T1 pelvic angle, C7-CSVL and odontoid CSVL offset, coracoid distance and angle. Sagittal cervical, spinopelvic, thoracolumbar and global parameters were measured.

Results

There was no significant difference between groups N and S for coronal parameters, except for L4 and L5 inclinations with a mean difference of 3,3° (p < 0,001). Global coronal alignment kept constant throughout age groups in N and S groups. Sagittal parameters varied with age: C2-C7 lordosis (p < 0,001), T1-T12 kyphosis (p < 0,001), pelvic incidence (p < 0,001). There was no correlation between global coronal and sagittal alignment: R-values ranging from -0.2 to 0.2.

Conclusion

Global coronal parameters were comparable in normal individuals and in scoliosis <35°. Coronal plane parameters were not influenced by age. Sagittal plane parameters varied significantly with age. There was no direct link between coronal et sagittal alignment.

Comparison of the Odontoid and Orbital-Coronal Vertical Axis Lines in Evaluating Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery

STUDY DESIGN

Asymptomatic Multi-Ethnic Alignment Normative Study (MEANS) cohort: cross-sectional, multicenter. Symptomatic cohort: retrospective, multisurgeon, single-center.

OBJECTIVE

To assess the association of odontoid-coronal vertical axis (OD-CVA) and orbital-coronal vertical axis (ORB-CVA) with radiographic parameters, patient-reported outcomes, and clinical outcomes.

SUMMARY OF BACKGROUND DATA

Previous literature studied the OD-CVA in an asymptomatic cohort and ORB-CVA in a symptomatic cohort, demonstrating their correlations with radiographic parameters and ORB-CVA with outcomes.

MATERIALS AND METHODS

A total of 468 asymptomatic adult participants were prospectively enrolled in the MEANS cohort. 174 symptomatic patients with adult spinal deformity with ≥6 fused levels and 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. The association between OD-CVA and ORB-CVA, and radiographic parameters, perioperative variables, PROs, and outcomes were analyzed. Pearson correlation was used to assess correlation and logistic regression odds of outcomes.

RESULTS

In the MEANS cohort, the ORB-CVA correlated with C7-CVA ( r = 0.58) and OD-CVA ( r = 0.74). In the symptomatic cohort, preoperative ORB-CVA correlated better with leg length discrepancy; r = 0.17, P = 0.029), whereas preoperative OD-CVA correlated better with C7-CVA ( r = 0.90, P < 0.001). Postoperative ORB-CVA correlated with postoperative C7-CVA ( r = 0.66, P < 0.001), and postoperative OD-CVA correlated strongly with postoperative C7-CVA ( r = 0.81, P < 0.001). Both preoperative OD-CVA ( r = 0.199) and ORB-CVA ( r = 0.208) correlated with the preoperative Oswestry Disability Index. ORB-CVA correlated better than OD-CVA in the preoperative Scoliosis Research Society-22r pain category but worse in total and other subcategories. Preoperative ORB-CVA was associated with increased odds of intraoperative complication (odds ratio = 1.28, 1.01-1.22), like OD-CVA (odds ratio = 1.30, 1.12-1.53). Neither preoperative ORB-CVA nor OD-CVA was associated with reoperations and readmissions after multivariate analysis. Preoperative OD-ORB mismatch >1.5 cm was not associated with increased odds of intraoperative and postoperative complications, reoperations, or readmissions.

CONCLUSION

ORB-CVA and OD-CVA correlated with radiographic parameters, patient-reported outcomes, and intraoperative complications. ORB-CVA and OD-CVA can be used interchangeably as cranial coronal parameters in adult spinal deformity surgery.

Practical Methods of Assessing Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery: A Comparative Analysis

STUDY DESIGN

Asymptomatic cohort: prospective, cross-sectional, multicenter. Symptomatic: retrospective, multisurgeon, single-center.

OBJECTIVE

To assess the association between cranial coronal alignment and adult spinal deformity (ASD) surgical risk and outcomes.

SUMMARY OF BACKGROUND DATA

ASD leads to decreased quality of life. Studies have shown that coronal malignment (CM) is associated with worse surgical outcomes.

MATERIALS AND METHODS

A total of 468 adult participants were prospectively enrolled in the asymptomatic cohort. Totally, 172 symptomatic ASD patients with 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. Three cranial plumb line parameters: the positions of the plumb lines from the midpoint between the medial orbital rims (ORB-L5), the odontoid (OD-L5), and the C7 centroid (C7-L5) relative to the L5 pedicle, were measured. Each subject had plumb line medial (M), touching (T), or lateral (L) to either pedicle. The association between each group of patients and radiographic parameters, intraoperative variables, patient-reported outcomes, and clinical outcomes were analyzed.

RESULTS

In the asymptomatic cohort, OD-L5 was medial to or touching the L5 pedicle in 98.3% of volunteers. In the symptomatic patients, preoperative OD-L5-L exhibited higher mean age (56.2±14.0), odontoid-coronal vertical axis (OD-CVA) (5.5±3.3 cm), Oswestry disability index (ODI) score (40.6±18.4), pelvic fixation rate (56/62, 90.3%), OR time (528.4±144.6 min), median estimated blood loss (1300 ml), and durotomy rate (24/62, 38.7%). A similar pattern of higher CVA, preoperative ODI, intraoperative pelvic fixation rate, OR time, estimated blood loss, and durotomy rate was observed in ORB-L5-L and C7-L5-L patients. Final follow-up postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis (13.0%) and pseudarthrosis (17.4%).

CONCLUSION

Preoperative OD-L5, ORB-L5, and C7-L5 lateral to pedicles were associated with worse preoperative ODI and higher intraoperative complexity. Postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis and pseudarthrosis. Postoperative CM, approximated by the cranial plumb line lateral to the L5 pedicles, was associated with sagittal plane complications.

Sagittal spinal alignment varies with an individual's race: results of the multi-ethnic alignment normative study (MEANS)

PURPOSE

Assess normative values of sagittal spinal and lower extremity alignment in asymptomatic volunteers of three difference races.

METHODS

Asymptomatic volunteers between the ages of 18-80 years were enrolled prospectively and then analyzed retrospectively from six different centers. Volunteers included reported no significant neck or back pain, nor any known spinal disorder(s). All volunteers underwent a standing full-body or full-spine low dose stereoradiograph. Volunteers were grouped into three main races; Asian (A), Arabo-Bèrbère (B), and Caucasian (C). The Asian volunteers included in this study were from Japan and Singapore.

RESULTS

There were statistical differences in the Age, ODI, and BMI of the volunteers from the three different races. Asian volunteers had the lowest age (A: 36.7, B: 45.5, C: 42.0) and BMI (A: 22.1, B: 27.1, C: 27.3). Pelvic morphology including pelvic incidence (A: 51.0, B: 52.0, C: 52.5, p = 0.37), pelvic tilt (A: 11.9, B: 12.3, C: 12.9, p = 0.44), and sacral slope (A: 39.1, B: 39.7, C: 39.6, p = 0.77) were similar amongst the 3 races. Regional spinal alignment was different between the groups. Thoracic Kyphosis (A: 32.9, B: 43.3, C: 40.0, p < 0.0001) and Lumbar lordosis (A: - 54.2, B: - 60.4, C: - 59.6, p < 0.0001) were lower in Asians compared to Caucasian and Arabo-Bèrbère volunteers despite having similar pelvic incidence.

CONCLUSION

Volunteers in the Asian group had lower lumbar lordosis and thoracic kyphosis when compared to the Arabo-Bèrbère and Caucasian groups while all groups had similar pelvic morphology. Thoracic Kyphosis had no correlation with Pelvic Incidence, while Lumbar Lordosis correlated well with both Thoracic Kyphosis and Pelvic Incidence. Thoracic kyphosis may be an independent variable in establishing adequate lumbar lordosis and varies based on an individual's race.