Analyzing lumbar vertebral shape and alignment in female patients with degenerative spondylolisthesis: Comparisons with spinal stenosis and risk factor exploration.

PURPOSE: This study aimed to examine the vertebral body shape characteristics and spondylopelvic alignment in L4 degenerative spondylolisthesis (DS) as well as the risk factors for the development of DS. METHODS: This cross-sectional study compared vertebral morphology and sagittal spinopelvic alignment in female patients with lumbar DS and lumbar spinal stenosis (LSS). The degree of lumbar lordosis (LL), pelvic incidence (PI), cross-sectional area (CSA), and vertebral body height ratio (ha/hp) of the lumbar spine were compared using full-length spine radiographs and computed tomography in 60 females with DS and in 60 women with LSS. RESULTS: No significant differences in age or body mass index were observed between the two groups; however, the DS and LSS groups significantly differed in PI (mean, 58.9±10.8 vs. 47.2±11.6, P < 0.001), L4 CSA (mean, 1,166.2 m2 vs. 1,242.0 m2, P = 0.002) and ha/hp (mean, 1.134 vs. 1.007, P < 0.001). The L4 ha/hp was significantly higher in the DS group than in the LSS group. Additionally, LL values were negatively correlated with vertebral L5 CSA in the DS group (r = -0.28, P < 0.05). The LSS and DS groups demonstrated positive correlations between LL and L2, L3, and L4 ha/hp (r = 0.331, 0.267, and 0.317; P < 0.01, < 0.05, and < 0.05, respectively) and between LL and L4 and L5 ha/hp (r = 0.333, 0.331; P < 0.01, respectively). Multivariate regression analyses revealed that PI and ha/hp ratio may be independent predictors of DS development. CONCLUSION: The DS group had significantly larger LL, PI, and L4 ha/hp and smaller L4 CSA than the LSS group. The lumbar vertebral body shape and sagittal spinopelvic alignment in females might be independent predictors of DS development.

Gender differences in spinal mobility during postural changes: a detailed analysis using upright CT.

Lumbar spinal alignment is crucial for spine biomechanics and is linked to various spinal pathologies. However, limited research has explored gender-specific differences using CT scans. The objective was to evaluate and compare lumbar spinal alignment between standing and sitting CT in healthy individuals, focusing on gender differences. 24 young and 25 elderly males (M) and females (F) underwent standing and sitting CT scans to assess lumbar spinal alignment. Parameters measured and compared between genders included lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lordotic angle (LA), foraminal height (FH), and bony boundary area (BBA). Females showed significantly larger changes in SS and PT when transitioning from standing to sitting (p = .044, p = .038). A notable gender difference was also observed in the L4-S LA among the elderly, with females showing a significantly larger decrease in lordotic angle compared to males (- 14.1° vs. - 9.2°, p = .039*). Females consistently exhibited larger FH and BBA values, particularly in lower lumbar segments, which was more prominent in the elderly group (M vs. F: L4/5 BBA 80.1 mm2 [46.3, 97.8] vs. 109.7 mm2 [74.4, 121.3], p = .019 in sitting). These findings underline distinct gender-related variations in lumbar alignment and flexibility, with a focus on noteworthy changes in BBA and FH in females. Gender differences in lumbar spinal alignment were evident, with females displaying greater pelvic and sacral mobility. Considering gender-specific characteristics is crucial for assessing spinal alignment and understanding spinal pathologies. These findings contribute to our understanding of lumbar spinal alignment and have implications for gender-specific spinal conditions and treatments.

Lumbar lordosis and sacral slope do not differ in two types of postoperative lumbar disc re-herniation: a cross-sectional observational study.

BACKGROUND: To identify the differences of lumbar lordosis (LL) and sacral slope (SS) angles between two types of postoperative lumbar disc re-herniation, including the recurrence of same level and adjacent segment herniation (ASH). METHODS: We searched the medical records of lumbar disc herniation (LDH) patients with re-herniation with complete imaging data (n = 58) from January 1, 2013 to December 30, 2020 in our hospital. After matching for age and sex, 58 patients with LDH without re-herniation from the same period operated by the same treatment group in our hospital were served as a control group. Re-herniation patients were divided into two groups, same-level recurrent lumbar disc herniation group (rLDHG) and adjacent segment herniation group with or without recurrence (ASHG). The preoperative, postoperative and one month after operation LL and SS were measured on standing radiographs and compared with the control group by using t-test, ANOVA, and rank-sum test. Next, we calculated the odds ratios (ORs) by unconditional logistic regression, progressively adjusted for other confounding factors. RESULTS: Compared with the control group, the postoperative LL and SS were significantly lower in LDH patients with re-herniation. However, there were no differences in LL and SS between ASHG and rLDHG at any stage. After progressive adjustment for confounding factors, no matter what stage is, LL and SS remained unassociated with the two types of re-herniation. CONCLUSIONS: Low postoperative LL and SS angles are associated with degeneration of the remaining disc. Low LL and SS may be independent risk factors for re-herniation but cannot determine type of recurrence (same or adjacent disc level).

CORRELATION OF SPINOPELVIC PARAMETERS WITH DISABILITY STATUS IN PATIENTS WITH DEGENERATIVE LUMBAR DISEASES.

Lumbar degenerative disease usually manifests in spine clinics. This study examines the spino-pelvic characteristics of lumbar degenerative disease patients as well as the clinical ramifications in the Indian population which help in early identification of sagittal spine anomalies. Purpose - to study the spinopelvic parameters and correlate them with disability status in patients with degenerative lumbar diseases. This cross-sectional observational study focused on patients aged 40 to 60, diagnosed with degenerative lumbar spine diseases, seen at the Orthopedics Outpatient Department. Thorough history, clinical examination, and disability assessment were conducted using the modified Oswestery Disability Questionnaire (ODI). Radiological evaluation included measuring spinopelvic parameters-Pelvic Incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS), and Lumbar Lordosis (LL)-correlated with disability. Disability status was determined through the Oswestry Low Back Pain Disability (ODI) Questionnaire. Among the study population, the difference in mean of Pelvic Tilt, Sacral slope, Lumbar lordosis, Pelvic incidence across disability status was not statistically significant. BMI and sacral slope showed positive correlation to sacral slope and negative correlation to Pelvic Tilt, Lumbar Lordosis, ODI. This study concluded there was no association between spinopelvic characteristics and level of disability in degenerative lumbar disease. Early detection of spinopelvic changes can aid in early intervention, slow down disease progression, and lessen impairment brought on by degenerative disc diseases.

A Novel Surgical Indication for Scheuermann's Kyphosis.

Scheuermann kyphosis can be treated surgically to restore proper sagittal alignment. Thoracic curves >70° are typically indicated for surgical intervention. However, patients who have reached their natural limit of compensatory lumbar hyperlordosis are at risk of accelerated degeneration. This can be determined by comparing lumbar lordosis on standing neutral radiographs and supine extension radiographs. Minimal additional lordosis in extension compared with neutral, abutment of the spinous processes, or greater lumbar lordosis standing than with attempted extension suggest the patient is maximally compensated. We present a case of an adolescent boy with Scheuermann kyphosis who had reached the limit of his hyperlordosis compensation reserve. He subsequently underwent a T4 to L2 posterior spinal fusion with T7 to T11 Ponte Smith-Petersen grade two osteotomies. He tolerated the procedure well with no intraoperative complications or neuromonitoring changes. The patient has continued to do well and progressed to normal activity at 5-month follow-up.

[Effect of Kümmell's disease with kyphosis on spinal-pelvic sagittal parameters].

OBJECTIVE: To explore the effect of Kümmell's disease with kyphosis on the sagittal morphology of the spine-pelvis. METHODS: A retrospective analysis of 34 patients of Kümmell's disease with kyphosis （Kümmell group） admitted from August 2015 to September 2022, including 10 males and 24 females with an average age of （71.1±8.5） years old. A control group of 37 asymptomatic population aged （69.3±6.7） years old was matched. Spinal-pelvic sagittal parameters were measured on the anterior-posterior and lateral X-rays of the whole spine in the standing position, including segmental kyphosis（SK） or thoracolumbar kyphosis（TLK）, thoracic kyphosis（TK）, lumbar lordosis（LL）, pelvic incidence（PI）, pelvic tilt（PT）, sacral slope（SS）, sagittal vertical axis（SVA）, T1 pelvic angle（TPA） and PI-LL. Vertebral wedge angle（WA） in Kümmell was measured and differences in parameters among groups were analyzed and the relationship between spino-pelvic parameters and WA, SK were also investigated. RESULTS: TK, SK, PT, SVA, TPA and PI-LL in Kümmell group were significantly larger than those in control group （P<0.05）, LL and SS in Kümmell group were significantly decreased than those in control group （P<0.05）, and there was no significant difference in PI between two groups （P>0.05）. In Kümmell group, WA（30.8±5.9）° showed a positive correlation with SK and TK（r=0.366, 0.597, P<0.05）, and SK was significantly correlated with LL and SS（r=0.539, -0.591, P<0.05）. Strong positive correlation between LL and PI, SS, SVA, TPA, PI-LL were also confirmed in patients with Kümmell with kyphosis（r=0.559, 0.741, -0.273, -0.356, -0.882, P<0.05）. CONCLUSION: Patients with Kümmell with kyphosis not only have segmental kyphosis, but also changes the overall spinal-pelvic sagittal parameters, including loss of lumbar lordosis, pelvic retrorotation, trunk forward tilt. The surgical treatment of Kümmell disease should not only pay attention to the recovery of the height of the collapsed vertebra, but also focus on the overall balance of the spine-pelvic sagittal plane for patients with kyphosis.

The analysis of segmental lordosis restored by oblique lumbar interbody fusion and related factors: building up preoperative predicting model.

BACKGROUND: Oblique lumbar interbody fusion (OLIF) procedures have the potential to increase the segmental lordosis by inserting lordotic cages, however, the amount of segmental lordosis (SL) changes can vary and is likely influenced by several factors, such as patient characteristics, radiographic parameters, and surgical techniques. The objective of this study was to analyze the impact of related factors on the amount of SL changes in OLIF procedures and to build up predictive model for SL changes. METHODS: This is a retrospective study involving prospectively enrolled patients. A total of 119 patients with 174 segments undergoing OLIF procedure were included and analyzed. The lordotic cages used in all cases had 6-degree angle. Radiographic parameters including preoperative and postoperative segmental disc angle (SDA, preSDA and postSDA), SDA changes on flexion-extension views (ΔSDA-FE), CageLocation and CageInclination were measured by two observers. Interobserver reliability of measurements were ensured by analysis of interclass correlation coefficient (ICC > 0.75). Pearson correlation coefficient analysis and multivariate linear regression were employed to identify factors related to SDA changes and to build up predictive model for SDA changes. RESULTS: The average change of segmental disc angle (ΔSDA, postSDA-preSDA) was 3.9° ± 4.8° (95% confidence interval [CI]: 3.1°-4.6°) with preSDA 5.3° ± 5.0°. ΔSDA was 10.8° ± 3.2° with negative preSDA (kyphotic), 5.0° ± 3.7° with preSDA ranging from 0° to 6°, and 1.0° ± 4.1° with preSDA> 6°. Correlation analysis revealed a significant negative correlation between ΔSDA and preSDA (r = - 0.713, P < 0.001), CageLocation (r = - 0.183, P = 0.016) and ΔSDA-FE (r = - 0.153, P = 0.044). In the multivariate linear regression, preSDA and CageLocation were included in the predictive model, resulting in minimal adjusted R2 change (0.017) by including CageLocation. Therefore, the recommended predictive model was ΔSDA = 7.9-0.8 × preSDA with acceptable fit. (adjusted R2 = 0.508, n = 174, P < 0.001). CONCLUSIONS: The restoration of segmental lordosis through OLIF largely depends on the preoperative segmental lordosis. The predictive model, which utilized preoperative segmental lordosis, facilitates preoperative planning for corrective surgery using the OLIF procedure.

Changes in cervical sagittal balance following anterior cervical discectomy with fusion.

INTRODUCTION: Change in the sagittal balance after anterior cervical discectomy with fusion (ACDF) is a phenomenon that has not yet been sufficiently studied. The aim of this study was to assess such changes. MATERIAL AND METHODS: 28 patients who underwent ACDF for cervical spondylosis were examined. The study was divided into three stages: preoperative, early postoperative, and late postoperative. Sagittal alignments were analysed based on X-ray AP and lateral images: angles C1-C7, C2-C7, C1-C2, C1-C4, C4-C7 and cervical sagittal vertical axis (cSVA). RESULTS: The cervical lordosis C2-C7 decreased by 13% in early monitoring, after which it increased by 60% in the late postoperative phase. Post hoc analysis showed that the measured values between early and late postoperative monitoring differed significantly. Cervical sagittal vertical axis (cSVA) increased by 23% in early control and then decreased by 18% in the late postoperative phase. Post hoc analysis showed that the measured values significantly differed between preoperative and early postoperative monitoring, and between early and late postoperative monitoring. CONCLUSIONS: We have shown that the long-term effect of ACDF is correction of the sagittal balance of the cervical spine. Immediately after the procedure, a disturbance in the cervical spine curvature to the morphology of the entire spine is observed.

Characteristics and standards of severe sagittal imbalance in adult patients with spinal deformities: a retrospective analysis.

OBJECTIVE: To analyze the characteristics of "severe" dynamic sagittal imbalance (DSI) in patients with adult spinal deformity (ASD) and establish criteria for them. METHODS: We retrospectively analyzed 102 patients with ASD presenting four cardinal signs of lumbar degenerative kyphosis. All patients underwent deformity corrective surgery and were divided into three groups according to the diagnostic criteria based on the Oswestry disability index and dynamic features (△Timewalk: time until C7 sagittal vertical axis [C7SVA] reaches ≥ 20 cm after the start of walking) of sagittal imbalance. The paravertebral back muscles were analyzed and compared using T2-weighted axial imaging. We performed a statistically time-dependent spinopelvic sagittal parameter analysis of full standing lateral lumbar radiographs. Lumbar flexibility was analyzed using dynamic lateral lumbar radiography. RESULTS: The patients were classified into the mild (△Timewalk ≥ 180 s, 35 patients), moderate (180 s > △Timewalk ≥ 30 s, 38 patients), and severe (△Timewalk < 30 s, 29 patients) groups. The back muscles in the severe group exhibited a significantly higher signal intensity (533.4 ± 237.5, p < 0.05) and larger area of fat infiltration (35.2 ± 5.4, p < 0.05) than those in the mild (223.8 ± 67.6/22.9 ± 11.9) and moderate groups (294.4 ± 214.7/21.6 ± 10.6). The analysis of lumbar flexibility revealed significantly lower values in the severe group (5.8° ± 2.5°, p < 0.05) than in the mild and moderate groups (14.2° ± 12.4° and 11.4° ± 8.7°, respectively). The severe group had significantly lower lumbar lordosis (LL, 25.1° ± 22.7°, p < 0.05) and Pelvic incidence-LL mismatch (PI-LL, 81.5° ± 26.6°, p < 0.001) than those of the mild (8.2° ± 16.3°/58.7° ± 18.8°) and moderate (14.3° ± 28.6°/66.8° ± 13.4°) groups. On receiver operating characteristic curve analysis, PI-LL was statistically significant, with an area under the curve of 0.810 (95% confidence interval) when the baseline was set at 75.3°. The severe group had more postoperative complications than the other groups. CONCLUSIONS: Our results suggest the following criteria for severe DSI: C7SVA > 20 cm within 30 s of walking or standing, a rigid lumbar curve < 10° on dynamic lateral radiographs, and a PI-LL mismatch > 75.3°.

Influences of lumbo-sacral transitional vertebrae for anterior lumbar interbody fusion.

Lumbo-sacral transitional vertebrae (LSTV) are frequent congenital variances of the spine and are associated with increased spinal degeneration. Nevertheless, there is a lack of data whether bony alterations associated with LSTV result in reduced segmental restoration of lordosis when performing ALIF. 58 patients with monosegmental stand-alone ALIF in the spinal segment between the 24th and 25th vertebra (L5/S1)/(L5/L6) where included. Of these, 17 patients had LSTV and were matched to a control population by age and sex. Pelvic incidence, pelvic tilt, sagittal vertical axis, lumbar lordosis, segmental lordosis, disc height and depth were compared. LSTV-patients had a significantly reduced segmental lordosis L4/5 (p = 0.028) and L5/S1/(L5/L6) (p = 0.041) preoperatively. ALIF resulted in a significant increase in segmental lordosis L5/S1 (p < 0.001). Postoperatively, the preoperatively reduced segmental lordosis was no longer significantly different in segments L4/5 (p = 0.349) and L5/S1/(L5/6) (p = 0.576). ALIF is associated with a significant increase in segmental lordosis in the treated segment even in patients with LSTV. Therefore, ALIF is a sufficient intervention for restoring the segmental lordosis in these patients as well.

Comparison of instrumented and stand-alone lateral lumbar interbody fusion for lumbar degenerative disease: a systematic review and meta-analysis.

BACKGROUND: Both instrumented and stand-alone lateral lumbar interbody fusion (LLIF) have been widely used to treat lumbar degenerative disease. However, it remains controversial as whether posterior internal fixation is required when LLIF is performed. This meta-analysis aims to compare the radiographic and clinical results between instrumented and stand-alone LLIF. METHODS: PubMed, EMBASE and Cochrane Collaboration Library up to March 2023 were searched for studies that compared instrumented and stand-alone LLIF in the treatment of lumbar degenerative disease. The following outcomes were extracted for comparison: interbody fusion rate, cage subsidence rate, reoperation rate, restoration of disc height, segmental lordosis, lumbar lordosis, visual analog scale (VAS) scores of low-back and leg pain and Oswestry Disability Index (ODI) scores. RESULTS: 13 studies involving 1063 patients were included. The pooled results showed that instrumented LLIF had higher fusion rate (OR 2.09; 95% CI 1.16-3.75; P = 0.01), lower cage subsidence (OR 0.50; 95% CI 0.37-0.68; P < 0.001) and reoperation rate (OR 0.28; 95% CI 0.10-0.79; P = 0.02), and more restoration of disc height (MD 0.85; 95% CI 0.18-1.53; P = 0.01) than stand-alone LLIF. The ODI and VAS scores were similar between instrumented and stand-alone LLIF at the last follow-up. CONCLUSIONS: Based on this meta-analysis, instrumented LLIF is associated with higher rate of fusion, lower rate of cage subsidence and reoperation, and more restoration of disc height than stand-alone LLIF. For patients with high risk factors of cage subsidence, instrumented LLIF should be applied to reduce postoperative complications.

Impact of obesity on adult spinal deformity (ASD) long-segment spinal fusion radiographic and clinical outcomes.

STUDY DESIGN: Retrospective chart review of patients receiving long-segment fusion during a five-year period. OBJECTIVE: To determine whether obese patients receive comparable benefits when receiving long-segment fusion compared to non-obese patients and to identify factors that may predict hardware failure and post-surgical complications among obese patients. METHODS: Demographic, spinopelvic radiographic, patient-reported outcome measures (PROMs), and complications data was retrospectively collected from 120 patients who underwent long-segment fusion during a five-year period at one tertiary care medical center. Radiographic measurements were pelvic incidence, pelvic tilt (PT), lumbar lordosis, L4-S1 lordosis, thoracic kyphosis, sagittal vertical axis, PI-LL mismatch, and proximal junction cobb angle at upper instrumented vertebrae + 2 (UIV+2). PROMs were Oswestry disability index, numeric rating scale (NRS) Back Pain, NRS Leg Pain, RAND SF-36 pain, and RAND SF-36 physical functioning. Included patients were adults and had at least 2-years of postoperative follow-up. Descriptive and multivariate statistical analysis was performed with α = 0.05. RESULTS: Patients with a BMI ≥ 30 (n=63) and patients with a BMI < 30 (n=57) demonstrated comparable improvements (P>0.05) for all spinopelvic radiographic measurements and PROMs. Each cohort demonstrated significant improvements from pre-assessment to post-assessment on nearly all spinopelvic radiographic measurements and PROMs (P<0.05), except PT and L4-S1 lordosis where neither group improved (p=0.95 and 0.58 for PT and P=0.23 and 0.11 for L4-S1 lordosis fornon-obese and obese cohorts respectively) and SF-36 physical functioning where the non-obese cohort not statistically improve (P=0.08). Patients with a BMI ≥ 30 demonstrated an increased incidence of cardiovascular complications (P=0.0293), acute kidney injury (P=0.0241), rod fractures (P=0.0293), and reoperations (P=0.0241) when compared to patients with a BMI < 30. CONCLUSION: This study adds to a growing body of evidence linking demographic factors with risks of hardware failure. Further, this data challenges the assumption that obese patients may not receive sufficient benefit to be long-segment surgical candidates. However, given their elevated risk for post-operative and delayed hardware complications, obese patients should be appropriately counseling before undergoing surgery.

Is spinopelvic mismatch associated with increased disability at 2 years following short-segment lumbar fusions?

OBJECTIVE: This study aimed to investigate the impact of pelvic incidence (PI) and lumbar lordosis (LL) matching on health-related quality of life (HRQOL) outcomes in patients undergoing one- or two-level lumbar fusions for degenerative pathology. The study also examined changes in alignment and HRQOL over a 24-month follow-up period. METHODS: A retrospective cohort study used data from a multicenter, prospectively collected database. Radiographic parameters were measured preoperatively and at 3-month and 24-month postoperative time points. Patients were categorized as having alignment (PI-LL ≤ 10°) or malalignment (PI-LL > 10°) at all time points. The Oswestry Disability Index scores were collected at the same time points. Statistical analyses assessed differences in HRQOL scores and radiographic parameters between the aligned and malaligned groups. RESULTS: Seventy-six patients were included. Both the aligned and malaligned groups showed improved HRQOL scores after surgery, but patients with proper alignment (PI-LL ≤ 10°) had significantly better HRQOL scores at the 24-month follow-up. Alignment remained stable from 3 months to 24 months postoperatively, with minimal movement between the aligned and malaligned groups. CONCLUSIONS: Proper PI-LL matching in one- and two-level lumbar fusions for degenerative pathology leads to improved HRQOL outcomes at the 24-month follow-up. Patients with maintained proper alignment after surgery experience continued improvement in disability levels. Surgeons should consider longer follow-up for patients who do not achieve proper alignment initially, as 24 months is crucial for assessing the consequences of malalignment in short-segment lumbar fusions.

Predictors of pelvic tilt normalization: a multicenter study on the impact of regional and lower-extremity compensation on pelvic alignment after complex adult spinal deformity surgery.

OBJECTIVE: The objective was to determine the degree of regional decompensation to pelvic tilt (PT) normalization after complex adult spinal deformity (ASD) surgery. METHODS: Operative ASD patients with 1 year of PT measurements were included. Patients with normalized PT at baseline were excluded. Predicted PT was compared to actual PT, tested for change from baseline, and then compared against age-adjusted, Scoliosis Research Society-Schwab, and global alignment and proportion (GAP) scores. Lower-extremity (LE) parameters included the cranial-hip-sacrum angle, cranial-knee-sacrum angle, and cranial-ankle-sacrum angle. LE compensation was set as the 1-year upper tertile compared with intraoperative baseline. Univariate analyses were used to compare normalized and nonnormalized data against alignment outcomes. Multivariable logistic regression analyses were used to develop a model consisting of significant predictors for normalization related to regional compensation. RESULTS: In total, 156 patients met the inclusion criteria (mean ± SD age 64.6 ± 9.1 years, BMI 27.9 ± 5.6 kg/m2, Charlson Comorbidity Index 1.9 ± 1.6). Patients with normalized PT were more likely to have overcorrected pelvic incidence minus lumbar lordosis and sagittal vertical axis at 6 weeks (p < 0.05). GAP score at 6 weeks was greater for patients with nonnormalized PT (0.6 vs 1.3, p = 0.08). At baseline, 58.5% of patients had compensation in the thoracic and cervical regions. Postoperatively, compensation was maintained by 42% with no change after matching in age-adjusted or GAP score. The patients with nonnormalized PT had increased rates of thoracic and cervical compensation (p < 0.05). Compensation in thoracic kyphosis differed between patients with normalized PT at 6 weeks and those with normalized PT at 1 year (69% vs 35%, p < 0.05). Those who compensated had increased rates of implant complications by 1 year (OR [95% CI] 2.08 [1.32-6.56], p < 0.05). Cervical compensation was maintained at 6 weeks and 1 year (56% vs 43%, p = 0.12), with no difference in implant complications (OR 1.31 [95% CI -2.34 to 1.03], p = 0.09). For the lower extremities at baseline, 61% were compensating. Matching age-adjusted alignment did not eliminate compensation at any joint (all p > 0.05). Patients with nonnormalized PT had higher rates of LE compensation across joints (all p < 0.01). Overall, patients with normalized PT at 1 year had the greatest odds of resolving LE compensation (OR 9.6, p < 0.001). Patients with normalized PT at 1 year had lower rates of implant failure (8.9% vs 19.5%, p < 0.05), rod breakage (1.3% vs 13.8%, p < 0.05), and pseudarthrosis (0% vs 4.6%, p < 0.05) compared with patients with nonnormalized PT. The complication rate was significantly lower for patients with normalized PT at 1 year (56.7% vs 66.1%, p = 0.02), despite comparable health-related quality of life scores. CONCLUSIONS: Patients with PT normalization had greater rates of resolution in thoracic and LE compensation, leading to lower rates of complications by 1 year. Thus, consideration of both the lower extremities and thoracic regions in surgical planning is vital to preventing adverse outcomes and maintaining pelvic alignment.

Three-column osteotomy in long constructs has lower rates of proximal junctional kyphosis and better restoration of lumbar lordosis than anterior column realignment.

PURPOSE: Three-column osteotomies (TCOs) and minimally invasive techniques such as anterior column realignment (ACR) are powerful tools used to restore lumbar lordosis and sagittal alignment. We aimed to appraise the differences in construct and global spinal stability between TCOs and ACRs in long constructs. METHODS: We identified consecutive patients who underwent a long construct lumbar or thoracolumbar fusion between January 2016 and November 2021. "Long construct" was any construct where the uppermost instrumented vertebra (UIV) was L2 or higher and the lowermost instrumented vertebra (LIV) was in the sacrum or ileum. RESULTS: We identified 69 patients; 14 (20.3%) developed PJK throughout follow-up (mean 838 days). Female patients were less likely to suffer PJK (p = 0.009). TCO was more associated with open (versus minimally invasive) screw/rod placement, greater number of levels, higher UIV, greater rate of instrumentation to the ilium, and posterior (versus anterior) L5-S1 interbody placement versus the ACR cohort (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.005, respectively). Patients who developed PJK were more likely to have undergone ACR (12 (32.4%) versus 2 (6.3%, p = 0.007)). The TCO cohort had better improvement of lumbar lordosis despite similar preoperative measurements (ACR: 16.8 ± 3.78°, TCO: 23.0 ± 5.02°, p = 0.046). Pelvic incidence-lumbar lordosis mismatch had greater improvement after TCO (ACR: 14.8 ± 4.02°, TCO: 21.5 ± 5.10°, p = 0.042). By multivariate analysis, ACR increased odds of PJK by 6.1-times (95% confidence interval: 1.20-31.2, p = 0.29). CONCLUSION: In patients with long constructs who undergo ACR or TCO, we experienced a 20% rate of PJK. TCO decreased PJK 6.1-times compared to ACR. TCO demonstrated greater improvement of some spinopelvic parameters.

What Happens to Sagittal Alignment Following Laminoplasty Versus Laminectomy and Fusion?

OBJECTIVE: Laminectomy and fusion (LF) and laminoplasty (LP) are 2 sucessful posterior decompression techniques for cervical myelo-radiculopathy. There is also a growing body of evidence describing the importance of cervical sagittal alignment (CSA) and its importance in outcomes. We investigated the difference between pre- and postoperative CSA parameters in and between LF or LP. Furthermore, we studied predictive variables associated with change in cervical mismatch (CM). METHODS: This is a retrospective cohort study of adults with cervical myeloradiculopathy in a single healthcare system. The primary outcomes are intra- and inter-cohort comparison of LF versus LP radiographic parameters at pre- and postoperative time points. A secondary multivariable analysis of predictive factors was performed evaluating factors predicting postoperative CM. RESULTS: Eighty nine patients were included; 38 (43%) had LF and 51 (57%) underwent LP. Both groups decreased in lordosis (LF 11.4° vs. 4.9°, P = 0.01; LP 15.2° vs. 9.1°, P < 0.001), increased in cSVA (LF 3.4 vs. 4.2 cm, P = 0.01; LP 3.2 vs. 4.2 cm, P < 0.001), and increased in CM (LF 22.0° vs. 28.5°, P = 0.02; LP 16.8° vs. 22.3°, P = 0.002). There were no significant differences in the postoperative CSA between groups. No significant predictors of change in pre- and postoperative CM were found. CONSLUSIONS: There were no significant pre-or postoperative differences following the 2 procedures, suggesting radiographic equipoise in well indicated patients. Across all groups, lordosis decreased, cSVA increased, and cervical mismatch increased. There were no predictive factors that led to change in cervical mismatch.

Defining the Post-Operative Progression of Degenerative Scoliosis: An Analysis of Cases without Instrument Failure.

OBJECTIVE: The expected post-operative changes in radiographic alignment over time remain poorly defined in patients surgically treated for degenerative scoliosis without instrument failure. Here we aim to describe the optimal natural progression of radiographic degenerative scoliosis at multiple timepoints in patients treated with a transforaminal lumbar interbody fusion (TLIF). METHODS: We identified an initial retrospective cohort of 114 patients treated with a TLIF for degenerative scoliosis between 2018 and 2022, with 39 patients ultimately meeting the imaging inclusion criteria. Patients who completed a primary or revision procedure with no evidence of instrument failure, proximal junctional kyphosis, or proximal junctional failure at last follow-up were included. Radiographic measurements of spinopelvic alignment were manually extracted from X-Ray scoliosis films. RESULTS: Thirty-nine patients (mean age 62.6 ± 8.7, mean follow-up 2.9 years), of which 23 underwent a primary TLIF (Primary) and 16 a revision procedure (Revision), were analyzed. Patients in the Primary group experienced a durable improvement in Thoracolumbar Cobb angle (-25° ± 15°), Thoracic Kyphosis (10° ± 13°), and Pelvic Incidence/lumbar lordosis mismatch (PI/LL) (-19° ± 19°) through the first year of follow-up. In the Revision group, at one year follow-up, all measures of spinopelvic alignment except PI/LL mismatch had reverted to pre-operative levels. Thoracolumbar Cobb angle decreased to a significantly greater degree in the Primary group compared to the Revision group. CONCLUSION: Primary TLIF operations without instrument failure consistently improve radiographic outcomes in three key measures through the first year. For revision procedures, there appears to be modest radiographic benefit at follow-up.

Sagittal Alignment in the Degenerative Lumbar Spine: Surgical Planning.

➤ Sagittal alignment of the spine has gained attention in the field of spinal deformity surgery for decades. However, emerging data support the importance of restoring segmental lumbar lordosis and lumbar spinal shape according to the pelvic morphology when surgically addressing degenerative lumbar pathologies such as degenerative disc disease and spondylolisthesis.➤ The distribution of caudal lordosis (L4-S1) and cranial lordosis (L1-L4) as a percentage of global lordosis varies by pelvic incidence (PI), with cephalad lordosis increasing its contribution to total lordosis as PI increases.➤ Spinal fusion may lead to iatrogenic deformity if performed without attention to lordosis magnitude and location in the lumbar spine.➤ A solid foundation of knowledge with regard to optimal spinal sagittal alignment is beneficial when performing lumbar spinal surgery, and thoughtful planning and execution of lumbar fusions with a focus on alignment may improve patient outcomes.

C4 constant vertebra: a novel benchmark of physiological cervical sagittal alignment.

BACKGROUND: Cervical sagittal alignment is essential, and there is considerable debate as to what constitutes physiological sagittal alignment. The purpose of this study was to identify constant parameters for characterizing cervical sagittal alignment under physiological conditions. METHODS: A cross-sectional study was conducted in which asymptomatic subjects were recruited to undergo lateral cervical spine radiographs. Each subject was classified according to three authoritative cervical sagittal morphology classifications, followed by the evaluation of variations in radiological parameters across morphotypes. Moreover, the correlations among cervical sagittal parameters, age, and cervicothoracic junction parameters were also investigated. RESULTS: A total of 183 asymptomatic Chinese subjects were enrolled with a mean age of 48.4 years. Subjects with various cervical sagittal morphologies had comparable C4 endplate slope angles under all three different typing systems. Among patients of different ages, C2-C4 endplate slope angles remained constant. Regarding the cervicothoracic junction parameters, T1 slope and thoracic inlet angle affected cervical sagittal parameters, including cervical lordosis and C2-7 sagittal vertical axis, and were correlated with the endplate slope angles of C5 and below and did not affect the endplate slope angles of C4 and above. In general, the slope of the C4 inferior endplate ranges between 13° and 15° under different physiological conditions. CONCLUSIONS: In the asymptomatic population, the C4 vertebral body maintains a constant slope angle under physiological conditions. The novel concept of C4 as a constant vertebra would provide a vital benchmark for diagnosing pathological sagittal alignment abnormalities and planning the surgical reconstruction of cervical lordosis.

Validation of Roussouly classification in predicting the occurrence of adjacent segment disease after short-level lumbar fusion surgery.

BACKGROUND: Recent studies demonstrated that restoring sagittal alignment to the original Roussouly type can remarkably reduce complication rates after adult spinal deformity surgery. However, there is still no data proving the benefit of maintaining ideal Roussouly shape in the lumbar degenerative diseases and its association with the development of adjacent segment disease (ASD). Thus, this study was performed to validate the usefulness of Roussouly classification to predict the occurrence of ASD after lumbar fusion surgery. MATERIALS AND METHODS: This study retrospectively reviewed 234 consecutive patients with lumbar degenerative diseases who underwent 1- or 2-level fusion surgery. Demographic and radiographic data were compared between ASD and non-ASD groups. The patients were classified by both "theoretical" [based on pelvic incidence (PI)] and "current" (based on sacral slope) Roussouly types. The patients were defined as "matched" if their "current" shapes matched the "theoretical" types and otherwise as "mismatched". The logistic regression analysis was performed to identify the factors associated with ASD. Finally, clinical data and spinopelvic parameters of "theoretical" and "current" types were compared. RESULTS: With a mean follow-up duration of 70.6 months, evidence of ASD was found in the 68 cases. Postoperatively, ASD group had more "current" shapes classified as type 1 or 2 and fewer as type 3 than the non-ASD group (p < 0.001), but the distribution of "theoretical" types was similar between groups. Moreover, 80.9% (55/68) of patients with ASD were mismatched, while 48.2% (80/166) of patients without ASD were mismatched (p < 0.001). A multivariate analysis identified age [odds ratio (OR) = 1.058)], 2-level fusion (OR = 2.9830), postoperative distal lordosis (DL, OR = 0.949) and mismatched Roussouly type (OR = 4.629) as independent risk factors of ASD. Among the four "theoretical" types, type 2 had the lowest lumbar lordosis, DL, and segmental lordosis. When considering the "current" types, current type 2 was associated with higher rates of 2-level fusion, worse DL, and greater pelvic tilt compared with other current types. CONCLUSIONS: DL loss and mismatched Roussouly type were significant risk factors of ASD. To decrease the incidence of ASD, an appropriate value of DL should be achieved to restore sagittal alignment back to the ideal Roussouly type. LEVEL OF EVIDENCE: Level 4.