Change In Sagittal Vertical Axis Research Articles

Perioperative Complications and Radiographic Outcomes Following Cervical Laminoplasty: A Review of 105 Cases from a Single Academic Center

To assess complications and to compare preoperative and postoperative radiographic measures in patients who underwent cervical laminoplasty. We evaluated patients undergoing cervical laminoplasty between 2011 and 2022 at an academic medical center. Patient demographics, intraoperative and postoperative complications, and preoperative and postoperative radiographic parameters were recorded. Of 150 patients undergoing cervical laminoplasty during 2011-2022, 105 met the inclusion criteria. We identified 22 (21.0%) adverse events in 20 patients: 4 intraoperative (3.8%), 10 perioperative (9.5%), and 8 delayed postoperative (7.6%). Among adverse events, 13 (12.4%) were judged to be minor and 9 (8.6%) were judged to be major complications. Revision surgery was required in 6 (5.7%) patients. Both preoperative and postoperative cervical spine radiographic imaging was available in 47 (44.8%) of the 105 patients. Mean preoperative and postoperative C2-7 Cobb angles were 14.7° and 12.3°, respectively (P= 0.04). Mean preoperative and postoperative sagittal vertical axis measurements were 29.2 mm and 33.3 mm, respectively (P= 0.07). Mean preoperative and postoperative T1 slopes were 32.3° and 30.2°, respectively (P= 0.07). Cervical laminoplasty carries a significant risk of adverse events, the majority of which are minor, and has a low rate of reoperation (5.7%). The procedure does not result in significant changes in sagittal vertical axis or T1 slope. Cervical laminoplasty remains a valuable surgical option for selected patients with cervical myelopathy.

Reoperation depending on time period following pedicle subtraction osteotomy for thoracolumbar kyphosis in patients with ankylosing spondylitis.

The aim of this study was to investigate time-dependent rates and indications of unplanned reoperation and to evaluate the most common indication depending on the time interval after pedicle subtraction osteotomy (PSO) for correction of thoracolumbar kyphosis in patients with ankylosing spondylitis (AS). A total of 321 consecutive patients with AS (284 men; mean age 43.8 years) with thoracolumbar kyphosis who underwent PSO were included. Patients who underwent reoperation after the index surgery were divided according to the duration of the follow-up period. A total of 51 patients (15.9%) underwent unplanned reoperations. The reoperation groups had greater preoperative and postoperative C7 sagittal vertical axis (SVA), and less lordotic postoperative osteotomy angle (-4.3° ± 18.6° vs -15.0° ± 13.7°, p < 0.001). The perioperative change in SVA was not significantly different between groups (-10.0 ± 7.1 cm vs -10.0 ± 5.1 cm, p = 0.970), while that in the osteotomy angle was significantly different (-22.4° ± 21.3° vs -30.0° ± 11.5°, p = 0.014). Most reoperations (45.1%; 23/51) were performed within 2 weeks of the initial operation. Within 2 weeks, the most common cause of reoperation was neurological deficit in 10 patients, with a cumulative reoperation rate of 3.2%. After 3 years, the most common complications were mechanical complications in 8 patients, accounting for 15.7% (8/51) of patients. Overall, the most common indications for reoperation were mechanical complications (17 patients; 5.3%), followed by neurological deficits (12 patients; 3.7%). PSO may be the most effective surgical procedure for the correction of thoracolumbar kyphosis in patients with AS. However, 51 patients (15.9%) required an unplanned reoperation.

226. Postoperative SVA >4 cm has no impact on neck pain scores after C2-T2 fusion for myelopathy: results from a multicenter cohort study

<h3>BACKGROUND CONTEXT</h3> Recent literature has examined the importance of cervical alignment with regards to health-related quality-of-life outcomes. Several cervical alignment parameters have been identified as potential goals for correction of cervical spinal deformities. Of these parameters, the C2-7 sagittal vertical axis (SVA) has been utilized as a measure of global cervical alignment, and previous work has suggested that achieving a postoperative SVA of 4 cm or less is ideal with regard to patient outcomes. <h3>PURPOSE</h3> The purpose of this study was to determine the impact of SVA on postoperative neck pain scores after posterior cervical laminectomy and fusion for myelopathy. <h3>STUDY DESIGN/SETTING</h3> We performed a retrospective review of a multicenter prospective cohort of patients undergoing posterior cervical laminectomy and fusion from C2-T2 for subaxial cervical stenosis and degenerative cervical myelopathy from 2011-2018. <h3>PATIENT SAMPLE</h3> A total of 173 patients were identified. <h3>OUTCOME MEASURES</h3> SVA and VAS neck pain scores were recorded. <h3>METHODS</h3> We collected demographic information and assessed cervical alignment on standing radiographs performed preoperatively as well as at 6 months or greater postoperatively. The cohort was divided into 2 groups based on a postoperative SVA of <4 cm or ≥4 based on established criteria. We then examined differences between the groups with regard to preoperative and postoperative alignment, demographics, and neck pain scores as measured by the visual analog scale. A univariate analysis was performed to assess for differences between the 2 groups. All statistical analyses were performed with JMP®Pro 14.1.0. <h3>RESULTS</h3> A total of 173 patients were identified for inclusion. In this cohort, 70 patients were identified as having a postoperative SVA <4 cm and 103 patients were identified as having an SVA ≥4cm. In both groups, the change in SVA showed a worsening of alignment. This was significantly higher in the SVA >4 cohort compared to the SVA <4 cohort (-11.6 vs -3.3, p<.001). There was also a significantly higher proportion of female patients in the SVA <4 cohort (54.3% vs 30.1%). Otherwise, there were no other significant differences in demographics between the 2 groups. Of the 173 patients, 108 patients (62.4%) had VAS neck pain scores recorded at greater than 6 months postoperatively. With regard to VAS neck pain scores, they improved in both groups with long-term follow-up. There was no significant difference between the cohorts with respect to neck pain scores at any time point. Using the established minimal clinically important difference for VAS neck pain following cervical surgery, we found that 61.9% of the SVA <4 cohort and 52.9% SVA >4 cohort achieved MCID with no significant difference between the groups (p = .432). <h3>CONCLUSIONS</h3> The primary goal for posterior cervical laminectomy and fusion in the treatment of degenerative myelopathy is to achieve adequate decompression of the spinal cord and a stable, fused spine. While previous work has established the importance of SVA alignment in treatment of cervical deformity, in this multicenter cohort of patients undergoing C2-T2 posterior cervical fusion for degenerative myelopathy, postoperative SVA >4 cm was not associated with a significant difference in long-term patient-reported outcomes with regard to neck pain. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Does the Change of Acetabular Anteversion Result From Lumbar Pedicle Subtraction Osteotomy in Ankylosing Spondylitis-Related Kyphosis After Primary Total Hip Arthroplasty?

Retrospective study. To analyze the change in acetabular anteversion (AA) after lumbar pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis who have already undergone total hip arthroplasty (THA). AS patients with thoracolumbar kyphosis following lumbar PSO from January 2005 to January 2020 were retrospectively reviewed. Only the patients performed with THA prior to the PSO were included. AA was measured on the full-length standing posterior-anterior radiographs using the ellipse method. Twenty patients (34 hips) with a mean age of 36.8 years (range, 22 to 63 years) were included. After lumbar PSO, AA was reduced from 18.59° to 5.85° (P < 0.001). Postoperative change in AA was correlated with the spinal deformity correction. Additionally, the change in AA postoperatively was correlated with pelvic incidence (PI) (R = 0.346, P = 0.045). Although the postoperative change in sagittal vertical axis (SVA) was larger in the patients after L2 or L3 PSO (153.97 mm vs 70.03 mm, P = 0.006), no difference was found in the postoperative change in AA (12.83° vs 10.96°, P = 0.540) compared with the patients following L1 PSO. AA was significantly decreased following lumbar PSO and the postoperative change in AA was correlated with the magnitude of spinal deformity correction. Notably, the effect of osteotomy level on the postoperative change in AA was limited in the AS patients underwent 1-level PSO.

A Novel Mathematical Model to Calculate the Osteotomy in Ankylosing Spondylitis.

The authors developed a mathematical model to the sagittal vertical axis (SVA) change in ankylosing spondylitis whom PSO is planned. The mathematical model was developed using trigonometric equations. No significant difference exists between postop SVA change amount and SVA calculated. The mathematical model is reliable in restoring the global sagittal balance.

221. Change in sagittal alignment after decompression alone in patients with lumbar spinal stenosis: a prospective cohort study

BACKGROUND CONTEXT Patients with lumbar spinal stenosis present with low back pain, numbness and pain in the legs and gait difficulties due to neurogenic claudication. Patients often walk in a stooped posture to increase the spinal canal diameter by stretching out the ligamentum flavum. This stooped posture leads to a positive sagittal balance. After decompressive surgery, patients may walk in a less stooped manner, improving their sagittal balance, which may lead to less back pain and improved patient reported outcomes. PURPOSE To determine if sagittal balance will improve in patients with spinal stenosis after decompression alone. STUDY DESIGN/SETTING Prospective longitudinal cohort study. PATIENT SAMPLE Patients with lumbar spinal stenosis who underwent decompression alone. OUTCOME MEASURES Oswestry Disability Index (ODI), visual analogue scale (VAS)- leg and back pain. METHODS This study compares preoperative and 6-month postoperative full-length 36” standing lateral and posterior-anterior x-rays and 1-year Oswestry Disability Index (ODI), visual analogue scale (VAS)- leg and back pain, in patients undergoing decompression alone without fusion for central or combined central and lateral stenosis, in patients 60 years and older from March 2016 until September 2017. The following radiographic parameters were measured coronal cobb angle (COBB), pelvic incidence (PI), sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence-lumbar lordosis ratio (PI-LL) and sacral slope (SS). RESULTS Forty-five patients (24 males and 21 females) were included. Patients had symptoms for more than 3 months at the time of surgery. Most patients were operated with a bilateral laminectomy over two levels. Sagittal balance showed a statistically significant change in SVA from 65.0mm to 48.6mm (p=0.009) and PI-LL mismatch 7.80 to 4.24 (p= 0.005). A small to moderate association was found between SVA and ODI both preoperatively (r=0.54, p= 0.001) and postoperatively (r=0.51, p= 0.001) and preoperative VAS-leg/back pain (r=0.60, p=0.001)/(r=0.42,p=0.009). CONCLUSIONS There is a statistically significant improvement in sagittal balance in patients undergoing decompression alone for lumbar spinal stenosis. Associations between the SVA and ODI and VAS-leg/back pain indicate that improvements in sagittal balance contribute to improvements in patient reported outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Hand grip strength as a surrogate marker for postoperative changes in spinopelvic alignment in patients with lumbar spinal stenosis

There are a few studies on the postoperative changes in sagittal alignment and corresponding factors, including hand grip strength (HGS) and muscle performance tests for lumbar spinal stenosis (LSS). Thus, we aimed to determine whether HGS can be a surrogate marker for global sagittal alignment changes after decompression with fusion surgery for LSS. This retrospective observational study included 91 patients who underwent spine fusion surgery for LSS. Radiological spinopelvic parameters, including sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), global tilt (GT), and T1 pelvic angle (T1PA), were analyzed preoperatively and 1 year after posterior decompression and fusion surgery. To assess muscle performance, the 6-m walk (SMT), timed up and go (TUGT), and sit-to-stand (STS) tests were conducted. The relationship between HGS and postoperative SVA was examined through multiple linear regression analysis. Additionally, the relationship between HGS and preoperative/postoperative radiologic spinopelvic parameters and muscle performance test results was analyzed through Pearson's correlation. HGS was significantly correlated with age, preoperative and postoperative SVA, and the muscle performance tests. Furthermore, HGS was a factor that can significantly influence postoperative SVA changes in multiple linear regression analyses. Therefore, HGS may be a good predictor of postoperative SVA change.

Recurrent Proximal Junctional Kyphosis

Proximal junctional kyphosis (PJK) is one of the most common radiographic forms of adjacent segment degeneration with an incidence as high as 50% in adult spinal deformity surgery. It is a multifactorial problem with much still to be learned about the etiology and the most efficacious prevention methods. The challenge of addressing PJK can certainly be amplified in patients that develop recurrent proximal junctional kyphosis (rePJK) after revision surgery for PJK, which occurs in up to 45% of revision PJK cases. Patients found to be at the greatest risk for rePJK are those that have a pelvic tilt change &gt;5 degrees, sagittal vertical axis change &gt;50 mm, pedicle screw fixation at the upper instrumented vertebra and a preoperative cervicothoracic sagittal vertical axis of &gt;40 mm. Often, factors that placed the patient at high risk for PJK following the initial surgery are still present such as compromised paraspinal musculature, poor bone quality and high overall frailty. This might account for the higher rates of surgical revision in cases of rePJK. At present, we are in need of a good method for addressing issues related to these patient characteristics. An overview of the challenge of rePJK and our current understanding of the complication is presented.

Different acute behaviors of pelvic incidence after long fusion to sacrum between elderly patients with severe and minor sagittal deformity: a retrospective radiographic study on 102 cases.

To compare the acute behaviors of pelvic incidence (PI) between elderly adult spinal deformity (ASD) patients with severe and minor sagittal deformity based on SRS-Schwab classification and to identify the mechanism of the variability in PI after long fusion to S1. Patients aged 60years or above with available radiographs were included. The following parameters were measured pre- and postoperatively: Thoracic kyphosis, thoracolumbar kyphosis (TLK), lumbar lordosis (LL), PI, pelvic tilt, sacral slope, sagittal vertical axis (SVA), PI-LL and T1 pelvic angle (TPA). Forty-two patients were found with severe sagittal deformity were assigned to Group S, and 60 patients with minor sagittal deformity were assigned to Group M. Immediately after surgery, lumbar curve, TLK and PI-LL were obviously corrected in both groups, while LL, PI, SVA and TPA were significantly increased in Group S alone. PI was significantly increased from 42.6 ± 4.7° to 51.7 ± 6.0° in Group S (P = 0.002), but changed from 45.4 ± 10.2° to 46.3 ± 10.3° in Group M without statistical significance. Pearson correlation analysis showed changes in PI was significantly correlated with changes in SVA (r = 0.415, P = 0.011) in patients with PI increased more than 5°. PI spontaneously increases in elderly ASD patients with severe sagittal deformity after long fusion to sacrum, while is relative invariable in those with minor sagittal deformity. Variation in PI could be considered as a secondary change compensating for the spinal sagittal malalignment under long spinal fusion in elderly patients.

Sagittal spinopelvic alignment after spinal fusion in degenerative lumbar scoliosis: a meta-analysis

Objective: This meta-analysis aimed to investigate the changes in sagittal spinopelvic alignment in degenerative lumbar scoliosis (DLS) from the preoperative state to the last follow-up.Methods: The MEDLINE via PubMed, Cochrane, Scopus, and Embase databases were searched for studies published between January 2010 and January 2019 evaluating radiological parameters including the coronal Cobb angle, sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) in DLS. Two authors performed data extraction independently. All discrepancies were resolved by consensus.Results: The 34 studies identified showed significant decreases in overall and subgroup Cobb angles from the preoperative state to the last follow-up. Both overall TK and LL were significantly increased from the preoperative state to the last follow-up. In subgroup analysis, LLs in the long fusion, combined approach, and posterior approach group were significantly increased at the final follow-up, but the LL increase in the short fusion group was not significant at the last follow-up. However, there was no significant change in SVA, PI, SS, and PT from the preoperative state to the last follow-up.Conclusions: A literature review identified 34 studies reporting preoperative and last follow-up data on spinal fusion in DLS. Despite heterogeneity, a limited meta-analysis showed significant improvement in the coronal Cobb angle, TK, and LL after spinal fusion in DLS. A large, randomized clinical trial would be necessary to validate our results.

The standing and sitting sagittal spinopelvic alignment of Chinese young and elderly population: does age influence the differences between the two positions?

To investigate the characteristics of standing and sitting spinopelvic sagittal alignment among Chinese healthy population with different age groups. This cross-sectional, prospective study included a total of 235 volunteers aged 19 to 71years. Volunteers were divided into two groups: group A (age ≤ 40years; n = 140) and group B (age > 40years, n = 95). Student's t test was performed to compare the sagittal parameters including sagittal vertical axis (SVA), T1 pelvic angle (TPA), cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL) and pelvic tilt (PT) between standing and sitting positions of two groups. Multiple regression was performed to explore the influence factors of differences between two positions. In the standing position, group B had larger SVA, TK, PT and TPA than group A. When moving from standing to sitting position, increased SVA and PT were found in both groups, accompanied by decreased LL and TK. However, despite similar change in SVA, group B presented with lesser changes in LL, PT and TPA than group A in sitting position. Age and gender independently influenced the difference in PT and LL. In the standing position, the older volunteers showed larger SVA, TPA, TK, CL and PT than young population. Both groups showed similar changes when moving from standing to sitting, but the differences between the positions were smaller in older population. These characteristics in the standing and sitting positions of different age groups should be considered when planning surgical reconstruction of sagittal alignment. These slides can be retrieved under Electronic Supplementary Material.

Development of a Novel Cervical Deformity Surgical Invasiveness Index.

Retrospective review. The aim of this study was to develop a novel surgical invasiveness index for cervical deformity (CD) surgery that incorporates CD-specific parameters. There has been a surgical invasiveness index for general spine surgery and adult spinal deformity, but a CD index has not been developed. CD was defined as at least one of the following: C2-C7 Cobb >10°, cervical lordosis (CL) >10°, cervical sagittal vertical axis (cSVA) >4 cm, chin brow vertical angle >25°. Consensus from experienced spine and neurosurgeons selected weightings for each variable that went into the invasiveness index. Binary logistic regression predicted high operative time (>338 minutes), estimated blood loss (EBL) (>600 mL), or length of stay (LOS) >5 days) based on the median values of operative time, EBL, and LOS. Multivariable regression modeling was utilized to construct a final model incorporating the strongest combination of factors to predict operative time, LOS, and EBL. Eighty-five CD patients were included (61 years, 66% females). The variables in the newly developed CD invasiveness index with their corresponding weightings were: history of previous cervical surgery (3), anterior cervical discectomy and fusion (2/level), corpectomy (4/level), levels fused (1/level), implants (1/level), posterior decompression (2/level), Smith-Peterson osteotomy (2/level), three-column osteotomy (8/level), fusion to upper cervical spine (2), absolute change in T1 slope minus cervical lordosis, cSVA, T4-T12 thoracic kyphosis (TK), and sagittal vertical axis (SVA) from baseline to 1-year. The newly developed CD-specific invasiveness index strongly predicted long LOS (R = 0.310, P < 0.001), high EBL (R = 0.170, P = 0.011), and extended operative time (R = 0.207, P = 0.031). A second analysis used multivariable regression modeling to determine which combination of factors in the newly developed index were the strongest determinants of operative time, LOS, and EBL. The final predictive model included: number of corpectomies, levels fused, decompression, combined approach, and absolute changes in SVA, cSVA, and TK. This model predicted EBL (R = 0.26), operative time (R = 0.12), and LOS (R = 0.13). Extended LOS, operative time, and high blood loss were strongly predicted by the newly developed CD invasiveness index, incorporating surgical factors and radiographic parameters clinically relevant for patients undergoing CD corrective surgery. 4.

Comparing Radiographic Parameters for Single-Level L5-S1 Interbody Fusion: Anterior Lumbar (ALIF) Versus Transforaminal Lumbar Interbody Fusion (TLIF)

Abstract INTRODUCTION The lumbosacral junction acts as a transition point between the mobile lumbar spine and the rigid pelvis. It is thereby susceptible to degenerative changes necessitating fusion at L5-S1. In this study, we compared radiographic outcomes observed from single-level anterior lumbar interbody fusion (ALIF) and transforaminal lumbar interbody fusion (TLIF) at this level. METHODS Retrospective review of single-level ALIF and TLIF with up to one level PSF at L5-S1 between May 2007 and October 2018 was undertaken. X-ray measurements were gathered for lumbar lordosis, segmental lordosis, pelvic tilt, sacral slope, pelvic incidence, pelvic incidence-lumbar lordosis mismatch, anterior/posterior disc height, and sagittal vertical axis. Computed tomography /magnetic resonance imaging was used to determine central canal area, sagittal diameter, foraminal height, and foraminal area. RESULTS A total of 47 ALIF patients and 50 TLIF patients were included. Patients averaged 53.7 ± 10.1 yr of age for ALIF and 49.4 ± 14.7 yr old for TLIF (P = .094) with significant differences (P = .0017) seen with gender as ALIF had 60.4% males and TLIF 70.0% females. Single-level ALIF led to significantly (P = .0010) more segmental lordosis (+5.75° ± 7.31°) than TLIF (+0.25° ± 6.55°), though differences in lumbar lordosis were not statistically significant (P = .52). ALIF significantly increased both anterior (+10.4 ± 4.32 mm vs +4.30 ± 3.55 mm; P &lt; .0001) and posterior disc height (+4.33 ± 3.32 mm vs + 2.98 ± 2.07 mm; P = .043) than TLIF. Changes in sagittal vertical axis also significantly differed (P = .030) with ALIF decreasing sagittal vertical axis by 17.8 ± 26.4 mm from +60.3 mm to + 42.5 mm, and TLIF increasing by 0.95 ± 25.8 mm from 39.9 mm to 40.9 mm. Pelvic tilt, sacral slope, pelvic incidence, pelvic incidence-lumbar lordosis mismatch had no significant differences. No statistically significant differences were observed with central canal area, sagittal diameter, foraminal height or foraminal area between ALIF and TLIF. CONCLUSION At L5-S1, the ALIF approach leads to increased segmental lordosis, disc height, while also decreasing sagittal vertical axis to a significant degree than TLIF. However, these two approaches were no different with regards to pelvic parameters and measures of central canal and foraminal decompression.

Relationship between body mass index and sagittal vertical axis change as well as health-related quality of life in 564 patients after deformity surgery.

Obesity, a condition that is increasing in prevalence in the United States, has previously been associated with poorer outcomes following deformity surgery, including higher rates of perioperative complications such as deep and superficial infections. To date, however, no study has examined the relationship between preoperative BMI and outcomes of deformity surgery as measured by spine parameters such as the sagittal vertical axis (SVA), as well as health-related quality of life (HRQoL) measures such as the Oswestry Disability Index (ODI) and Scoliosis Research Society-22 patient questionnaire (SRS-22). To this end, the authors sought to clarify the relationship between BMI and postoperative change in SVA as well as HRQoL outcomes. The authors performed a retrospective review of a prospectively managed multicenter adult spinal deformity database collected and maintained by the International Spine Study Group (ISSG) between 2009 and 2014. The primary independent variable considered was preoperative BMI. The primary outcome was the change in SVA at 1 year after deformity surgery. Postoperative ODI and SRS-22 outcome measures were evaluated as secondary outcomes. Generalized linear models were used to model the primary and secondary outcomes at 1 year as a function of BMI at baseline, while adjusting for potential measured confounders. Increasing BMI (compared to BMI < 18) was not associated with change of SVA at 1 year postsurgery. However, BMIs in the obese range of 30 to 34.9 kg/m2, compared to BMI < 18 at baseline, were associated with poorer outcomes as measured by the SRS-22 score (estimated change -0.47, 95% CI -0.93 to -0.01, p = 0.04). While BMIs > 30 appeared to be associated with poorer outcomes as determined by the ODI, this correlation did not reach statistical significance. Baseline BMI did not affect the achievable SVA at 1 year postsurgery. Further studies should evaluate whether even in the absence of a change in SVA, baseline BMIs in the obese range are associated with worsened HRQoL outcomes after spinal surgery.

Technical Consideration for TLIF Cage Retrieval and Deformity Correction With Anterior Interbody Fusion in Lumbar Revision Surgeries

IntroductionSymptomatic pseudoarthrosis after transforaminal lumbar interbody fusion (TLIF) could result in sagittal malalignment. Revision posterior surgery with TLIF cage removal poses a challenge intraoperatively. The authors have proposed salvage anterior approach for cage removal and have discussed unique experience with the correction in their deformity patients. MethodsAll patients with symptoms of clinical deformity or symptomatic pseudoarthrosis operated from January of 2012 to February of 2018 were included in the study. TLIF cage removal followed by anterior lumbar interbody fusion (ALIF) surgery was performed in all patients. Radiographic sagittal parameters including thoracic kyphosis (TK; T4–T12), sagittal vertical axis (SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), the mismatch between pelvic incidence (PI) and LL (PI-LL), sacral slope (SS), pelvic tilt (PT), and PI were analyzed. Results6 patients (mean age of 57 years, 83% female) underwent TLIF retrieval through anterior approach and ALIF with hyperlordotic cages (HLCs), followed by posterior spinal fusion surgery. Described technique entails use of tailored instruments with sequential gentle distraction of end plates with TLIF spreader could facilitate in the cage removal. Mean number of interbody levels fused pre as well as post were 1.5. The radiographic sagittal parameters from preoperative versus postoperative standing were as follows: T4–T12 TK, 16° vs. 37.6°; LL, −25° vs. −47.6°; PT, 36° vs. 26°; PI-LL, 35° vs. 12.4°; SVA, 12° vs. 5.6°; and TPA, 44° vs. 25°, with p<.001. Mean number of instrumented level fused were 8.1. Using linear regression analysis, change from pre-to postoperative standing in LL predicted pre-to postoperative change in SVA and TPA for global correction (R= −0.30 and −0.80, respectively). ConclusionsAnterior approach is a suitable technique for TLIF cage removal while preserving the end plates for subsequent optimal interbody fusion at the index level in symptomatic pseudoarthrosis patients or those with clinical deformity. ALIF with HLCs with or without Ponte osteotomy can restore segmental and overall sagittal alignment.

Comparing Allografts to Autografts for Maintenance of Cervical Sagittal Parameters and Clinical Outcomes Following Anterior Cervical Discectomy and Fusion With Anterior Cervical Plating.

ObjectiveCurrent literature has not shown if using either allograft or autograft differentially affects postoperative cervical sagittal parameters. The goal of this study was to compare sagittal alignment and patient-reported outcomes following anterior cervical discectomy and fusion (ACDF) with allograft versus autograft. MethodsA retrospective cohort analysis of patients who underwent single-level ACDF was conducted. Preoperative, immediate postoperative, and final follow-up radiographic assessments were conducted and included: change in C2–7 lordosis, T1 slope, levels fused, sagittal vertical axis (SVA), fusion mass lordosis, and proximal and distal adjacent segment degeneration (ASD). Patient-reported outcomes were obtained using the Neck Disability Index and visual analogue scale scores for neck and arm. ResultsA total of 404 patients were assessed; 353 using allograft and 51 using autograft. No significant differences existed in demographics. Cervical lordosis improved in both groups without significant changes in SVA. Autograft group had a significantly greater amount of lordosis at the proximal segment on immediate postoperative radiographs and less overall cervical lordosis at final follow-up. Sagittal parameters were similar at each time point without significant changes between the 3-time points. No significant differences existed in radiographic ASD or reoperation rates. Fusion rates exceeded 96% in both groups. No significant differences existed between preoperative, postoperative, or change in patient-reported outcomes between the 2 groups. ConclusionSagittal alignment is maintained following ACDF when using either allograft or autograft. Radiographic evidence of ASD is present in both groups; however, this was not considered clinically significant, given low rates of pseudarthrosis or reoperation. No significant differences exist between groups in terms of patient-reported outcomes.

Anterior cervical discectomy and fusion can restore cervical sagittal alignment in degenerative cervical disease.

The purpose of this study was to evaluate its effect on the restoration and maintenance of cervical sagittal alignment in usual cervical degenerative diseases without preoperative sagittal malalignment. We retrospectively evaluated 108 patients who were diagnosed with degenerative cervical disease and underwent ACDF (allograft and plating) with > 1-year follow-up. For radiographic evaluation, we analysed segmental and C2-7 cervical lordosis, disc height, C2-7 sagittal vertical axis (SVA), T1 slope, and T1 slope minus C2-7 lordosis (T1S - CL) in lateral X-ray. Clinical assessment was based on arm VAS, neck VAS, and NDI scores. Correlation analysis was performed across the pre-post-changes in radiological parameters. Correlations between the changes in radiological and clinical parameters at final follow-up were also analysed. C2-7 lordosis was 7.13° preoperatively and increased to 13.06° (p < 0.001) and maintained at 10.08° at final follow-up (p = 0.007). Segmental lordosis increased from 0.66° to 8.33° and maintained at 5.19° (p < 0.001). Segmental disc height was 4.67mm preoperatively (increased to 7.13mm postoperatively and decreased to 5.74mm at final follow-up) (p < 0.001). SVA distance (31.53mm to 30.02mm) (p = 0.750) and T1 slope (30.03° to 31.37°) did not show meaningful change after surgery. Increase in segmental lordosis was correlated to an increase in C2-7 lordosis (p < 0.001). C2-7 SVA change correlated with both the T1 slope change (p < 0.001) and T1S - CL (p = 0.012). Change in SVA was correlated to a change in segmental lordosis and T1 slope (p = 0.003, p = 0.014). Clinical outcomes did not correlate with radiological findings. ACDF for the treatment of degenerative cervical disease without preoperative deformity was effective in restoring cervical sagittal alignment. Improvement of segmental lordosis related to an improvement in C2-7 lordosis and SVA. Radiological sagittal alignment did not show any relation with clinical outcomes in usual degenerative cases.

Cervical spine alignment following surgery for adolescent idiopathic scoliosis (AIS): a pre-to-post analysis of 81 patients

BackgroundSeveral studies have emphasized the importance of restoring thoracic kyphosis (TK) in the setting of AIS, but very few have discussed changes in cervical spine alignment following surgery. Aim of this study was to evaluate reciprocal cervical alignment change after modification of global and regional thoracolumbar alignment with surgery in the setting of adolescent idiopathic scoliosis (AIS).MethodsBaseline and 2-yrs follow-up radiographs of AIS patients (n = 81) were analysed measuring cervical parameters (upper cervical: C2-C0, McGregor Slope; lower cervical: C2-C7, C2-C7 sagittal vertical axis (SVA), C2-T3, C2-T3SVA, C2-T1Harrison (C2-T1Ha), T1 Slope (T1S)), thoracic, lumbar, pelvic and global alignment parameters. Post-operatively, patients were grouped twice; based on changes in TK and SVA. Cervical alignment was compared between groups. Pearson correlation was conducted to examine the relationship between changes in TK, SVA, and cervical alignment.ResultsStratification by change in TK, revealed significant alteration of lower cervical alignment T1S [p < 0.001]), C2-T3 [p = 0.019], C2-T1Ha [p = 0.043]), but there was no reciprocal change in the upper cervical spine. Stratification by SVA revealed a significant coexisting change in the lower cervical spine (T1S [p < 0.001], C2-C7SVA [p = 0.034], C2-T3 [p = 0.023], C2-T3SVA [p = 0.001]). SVA change was not associated to a change in the upper cervical spine. The correlation analysis showed that with a post-operative increase in TK, the cervical spine became more lordotic. Changes in TK were significantly correlated with: ΔT1S, ΔC2-C7, ΔC2-T3, and ΔC2-T3SVA. Similarly, increased cervical kyphosis was found when SVA was decreased post-operatively. Furthermore, there was a significant correlation between change of SVA and both ΔC2-T3 and ΔC2-T3SVA.ConclusionsIn surgically treated AIS patients, changes in global and regional alignment of the thoracolumbar and cervical spinal segments exhibit interdependence. Thus, surgical planning with regard to sagittal deformity in AIS patients should account for the post-operative impact on cervical alignment.

Global spinal deformity from the upper cervical perspective. What is "Abnormal" in the upper cervical spine?

Hypothesis:Reciprocal changes in the upper cervical spine correlate with adult TL deformity modifiers.Design:This was a retrospective review.Introduction:The upper cervical spine has remarkable adaptability to wide ranges of thoracolumbar (TL) deformity.Methods:Patients >18 years with adult spinal deformity (ASD) and complete radiographic data at baseline (BL) and 1 year were identified. Patients were grouped into component types of the Roussouly classification system (Type 1: Pelvic incidence [PI] <45° and lumbar lordosis [LL] apex below L4; Type 2: PI <45° and LL apex above L4; Type 3:45°<PI <65°; and Type 4: PI >65°). Patients were categorized by increasing severity of Schwab modifiers at BL (0, +, and ++) and further grouped by regional malalignment moving cranially (P: pelvic only; LP: lumbopelvic; TL: thoracic and LP; C: subaxial and TL). Analysis of variance and Pearson's r assessed changes in BL upper cervical parameters (C0-2, C0 slope, McGregor's Slope [MGS], and CBVA) across groups.Results:A total of 343 ASD patients were analyzed. When grouped by BL Schwab and Roussouly, Group P had the lowest BL disability compared to other Groups, while Roussouley Type 1 correlated with higher BL disability compared to Type 2. Moving cranially up the spine, Group P, Group LP, and Group TL did not differ in C0-2 angle, C0 slope, MGS, or CBVA. Group C had a significantly smaller C0-C2, and more negative MGS, C0 slope, and CBVA than noncervical groups. Type 1 trended slightly higher CBVA and MGS than types 2–4, but no differences in cervical lordosis, C0-C2, or C0S were found. MGS (r = −0.131, P = 0.015), CBVA (r = −0.473, P < 0.001), and C0S (r = −0.099, P = 0.042) correlated most strongly with sagittal vertical axis (SVA) compared to other Schwab modifiers. We found SVA > 34 mm predicted a 1 unit (°°) decrease in MGS (odds ratio [OR]: 0.970 [0.948–0.993], P = 0.010), while cervical SVA >51 mm predicted a 1 unit increase in MGS (OR: 1.25 [1.12–1.38], P < 0.001).Conclusions:Our study suggests that upper cervical alignment remains relatively stable through most broad variations of adult TL deformity. Changes in SVA correlated most with upper cervical changes.

Postoperative lower limb compensation in patient with adult spinal deformity

The objective of this study was to determine whether inadequate decompensation of spine and pelvis would lead to persistent compensatory action of lower extremity. Patients who underwent adult spinal deformity from January 2014 to December 2016 were included. Postoperatively, patients who showed persistent lower extremity compensation (femur obliquity angle/FOA ≥ 5°) were classified into compensated lower extremity (CLE) group and decompensated lower extremity (DLE) group with FOA < 5°. Sagittal vertical axis (SVA), T1 spinopelvic inclination, TPA (T1 pelvic angle), thoracic kyphosis, lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt, sacral slope and FOA were measured and compared between two groups. The lack of lumbar lordosis was assessed by PI-LL mismatch and multivariate analysis were used to investigate correlation in changes of parameters. 115 patients were classified into CLE group (23 patients) and DLE group (92 patients). Thoracic compensations were more prevalent in the CLE group while pelvic compensation was more prominent in the DLE group. Both postoperative TPA and PI-LL in the CLE group were greater than those in the DLE group while postoperative SVA was similar. At 1 year postoperatively, SVA was increased in the CB group with persistent lower extremity compensation. Changes in FOA had moderate correlation with changes in SVA and strong correlation with changes in TPA. In conclusion, postoperative persistent lower limb compensation can be interpreted into surgical undercorrection. TPA rather than SVA is a useful parameter to assess global alignment and compensatory action of the lower extremity.