Sagittal Vertical Axis Correction Research Articles

Comparative analysis of early versus late surgical intervention for lumbosacral hemivertebra: a minimum 2-year follow-up retrospective study

BACKGROUND CONTEXTLumbosacral hemivertebra (LSHV) is a complex and unique congenital spinal deformity characterized by early severe trunk imbalance and progressive compensatory curve. Previous studies have proved the efficiency of posterior LSHV resection. However, the optimal timing for surgical intervention of LSHV still remains controversial. Few studies compare the surgical outcomes in patients of different age groups. PURPOSETo evaluate the influence of posterior-only LSHV resection surgery timing on clinical and radiographic results. STUDY DESIGNRetrospective analysis. PATIENT SAMPLEWe retrospectively analyzed 58 LSHV patients undergoing posterior-only LSHV resection with short-segment fusion at our institution between 2010 and 2020, with a mean follow-up of 7.5 years. OUTCOME MEASUREThe following data were observed for all cases: patient demographics, clinical outcomes measured by operating time, intraoperative blood loss, complications, and Health-Related Quality of Life, radiographic parameters included Cobb angles, trunk shift and sagittal spinal parameters. METHODSFrom 2010 to 2020, a consecutive series of 58 LSHV patients treated by posterior LSHV resection with short segmental fusion were investigated retrospectively, with a 7.5-year average follow-up period. Patients were stratified into 2 groups based on the timing of surgery: Group E (≤6 years old, representing the early-surgery) and Group L (>6 years old, representing the late-surgery). Radiographic assessments included pre- and postoperative measurements of main scoliosis, compensatory scoliosis, trunk shift, and sagittal balance parameters. Operative data, perioperative complications and SRS-22 questionnaires were also collected. RESULTSCompared to Group L, Group E exhibited a lower intraoperative blood loss (p<.001), higher final main curve correction rate (p=.037), smaller post-op compensatory curve (p=.031), higher sagittal vertical axis correction rates at immediate post-op (p=.045) and last follow-up (p=.027), and lower implant failure complications incidence (p=.006). CONCLUSIONThis study suggested that early surgical intervention in LSHV patients can achieve better correction outcomes, while reducing blood loss and postoperative complications in a large-scale cohort.

Durability of substantial clinical benefit leading to optimal outcomes in adult spinal deformity corrective surgery: a minimum 5-year analysis.

The objective was to evaluate factors associated with the long-term durability of outcomes in adult spinal deformity (ASD) patients. Operative ASD patients fused from at least L1 to the sacrum with baseline (BL) to 5-year (5Y) follow-up were included. Substantial clinical benefit (SCB) in Oswestry Disability Index (ODI), numeric rating scale (NRS)-back, NRS-leg, and Scoliosis Research Society (SRS)-22r scores and physical component score were assessed on the basis of previously published values. Factors were evaluated on the basis of meeting optimal outcomes (OO) at 2 years (2+) and 5 years (5+). Furthermore, 2+ patients were isolated and evaluated on the basis of meeting OO at 5 years (2+5+) or not at 5 years (2+5-). OO were defined as follows: no reoperation, major mechanical failure, proximal junctional failure, and meeting either 1) SCB in terms of ODI score (decrease > 18.8) or 2) ODI < 15 and SRS-22r total > 4.5. In total, 330 ASD patients met the inclusion criteria, with 45.5% meeting SCB for ODI at 2 years, while 46.0% met SCB at 5 years; 79% of those who achieved 2-year (2Y) SCB went on to achieve 5Y SCB. This rate was lower for OO, with 41% achieving 2Y OO (2+), while 37% met 5Y OO (5+) and 80% of 2+ patients had durable outcomes until 5+ (32% of the total cohort). Of the patient factors, frailty was significantly different among groups at 2 years, while comorbidity burden was significantly different at 5 years and the combination thereof differed in those with durable outcomes. Those who regained their level of activity postoperatively had 4 times higher odds of maintaining OO from 2 years to 5 years (p < 0.05). Osteoporosis rates, although equivocal at BL, were higher at the last follow-up in those who met 2Y OO but failed to meet 5Y OO. The odds of achieving OO at 5 years in 2+ patients decreased by 47% for each additional comorbidity and decreased by 74% in those who had lower-extremity paresthesias at BL (both p < 0.05). Controlling for patient factors and BL disability found fewer levels fused, decreased correction of sagittal vertical axis, and increased correction of pelvic incidence-lumbar lordosis mismatch to be predictive of maintaining 2Y OO until 5 years (p < 0.05). SCB was met in 46% of ASD patients at 5 years. The durability of OO was seen in a third of patients until 5 years postoperatively. Higher rates of medical complications were seen in those who failed to achieve and maintain OO until 5 years. Frailty and comorbidity burden were significant factors associated with the achievement and durability of OO until 5 years.

Are Surgical Outcomes Different According to Baseline Balance Status in Elderly Patients with Degenerative Sagittal Imbalance?

Retrospective study. We sought to compare surgical outcomes according to baseline balance statuses in elderly patients with degenerative sagittal imbalance (DSI). Although optimal sagittal correction has been emphasized for good surgical outcomes, the effect of the state of preoperative balance on surgical outcome has been adequately described at present. Patients aged ≥60 years with DSI who underwent ≥5-level fusion to the sacrum were included. Among them, only those who postoperatively achieved the optimal age-adjusted pelvic incidence (PI) - lumbar lordosis (LL) target were included in this study. Study participants were divided into two groups according to their preoperative sagittal vertical axis (SVA): compensatory balance (SVA <5cm, group CB) and decompensation (SVA ≥5cm, group D). Comparisons between the two groups were performed using the chi-squared test or Fisher's exact test for categorical variables and the independent t- test or Wilcoxon rank- sum test for continuous variables. A total of 156 patients whose postoperative sagittal alignment matched the age-adjusted PI-LL target constituted the study cohort. There were 59 patients in group CB and 97 patients in group D. Mean follow-up duration was 50.0 months after surgery. Immediate postoperatively, sacral slope and SVA were significantly greater in group D than in group CB. At last follow-up, the SVA was significantly greater in group D than in group CB (43.6 vs. 22.7mm), while no significant differences were found in other sagittal parameters. The Oswestry disability index and Scoliosis Research Society -22 scores at the last follow-up were significantly worse in group D than in group CB. The SVA tended to experience less correction postoperatively, with evidence of further deterioration during follow-up in group D than in group CB. This suboptimal correction of SVA may contribute to the inferior clinical outcomes encountered in group D relative to group CB. Therefore, we recommend correction of PI-LL as close as possible to the lower limit of the suggested PI-LL target range in patients with evidence of preoperative decompensation.

Is the pelvic incidence a determinant factor for kyphosis curve patterns of ankylosing spondylitis patients?

To investigate the influence of pelvic incidence (PI) on the kyphosis curve patterns and clinical outcomes in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis and to construct a classification of AS according to the PI value for surgical decision-making. 107 AS patients underwent single-level lumbar pedicle subtraction osteotomy (PSO) and finished a minimal of 2-year follow-up. All patients were divided into three groups: low PI (PI ≤ 40°), moderate PI (40° < PI ≤ 60°), and high PI (PI > 60°). Standing lateral radiographs were taken to evaluate the location of kyphotic apex, thoracic kyphosis (TK), lumbar lordosis (LL), C7 sagittal vertical axis (SVA), spino-sacral angle (SSA), global kyphosis (GK), PI, sacral slope (SS), and pelvic tilt (PT). Visual Analogue Scale (VAS) score, Oswestry Disability Index (ODI) and Bath Ankylosing Spondylitis Functional Index (BASFI) were used to evaluate quality of life. Before surgery, a significant difference was shown in the average LL and the mean GK in high PI group was the largest among the three groups. Correction of SVA, GK and LL in high PI group was the smallest among the three group. No significant difference in clinical outcomes was found among the three groups before surgery and at the final follow-up. Regarding the preoperative sagittal profile, the kyphosis curve pattern of moderate PI group is similar to that of low PI group. For AS patients in these two groups, harmonious sagittal alignment can be restored by a single-level PSO. However, the sagittal imbalance is insufficiently realigned by a single-level PSO in a patient with high PI.

Spinal deformity surgery in patients for whom blood transfusion is not an option: a single-center experience.

Spinal deformity surgery is associated with significant blood loss, often requiring the transfusion of blood and/or blood products. For patients declining blood or blood products, even in the face of life-threatening blood loss, spinal deformity surgery has been associated with high rates of morbidity and mortality. For these reasons, patients for whom blood transfusion is not an option have historically been denied spinal deformity surgery. The authors retrospectively reviewed a prospectively collected data set. All patients declining blood transfusion who underwent spinal deformity surgery at a single institution between January 2002 and September 2021 were identified. Demographics collected included age, sex, diagnosis, details of any prior surgery, and medical comorbidities. Perioperative variables included levels decompressed and instrumented, estimated blood loss, blood conservation techniques used, length of surgery, length of hospital stay, and complications from surgery. Radiographic measurements included, where appropriate, sagittal vertical axis correction, Cobb angle correction, and regional angular correction. Spinal deformity surgery was performed in 31 patients (18 male, 13 female) over 37 admissions. The median age at surgery was 41.2 years (range 10.9-70.1 years), and 64.5% had significant medical comorbidities. A median of 9 levels (range 5-16 levels) were instrumented per surgery, and the median estimated blood loss was 800 mL (range 200-3000 mL). Posterior column osteotomies were performed in all surgeries, and pedicle subtraction osteotomies in 6 cases. Multiple blood conservation techniques were used in all patients. Preoperative erythropoietin was administered prior to 23 surgeries, intraoperative cell salvage was used in all, acute normovolemic hemodilution was performed in 20, and perioperative administration of antifibrinolytic agents was performed in 28 surgeries. No allogenic blood transfusions were administered. Surgery was staged intentionally in 5 cases, and there was 1 unintended staging due to intraoperative blood loss from a vascular injury. There was 1 readmission for a pulmonary embolus. There were 2 minor postoperative complications. The median length of stay was 6 days (range 3-28 days). Deformity correction and the goals of surgery were achieved in all patients. Two patients underwent revision surgery during the follow-up period: one for pseudarthrosis and the other for proximal junctional kyphosis. With proper preoperative planning and judicious use of blood conservation techniques, spinal deformity surgery may be performed safely in patients for whom blood transfusion is not an option. The same techniques can be applied widely to the general population in order to minimize blood loss and the need for allogeneic blood transfusion.

Remodeling morphology of the subluxated osteotomy vertebra in closing-opening wedge osteotomy in ankylosing spondylitis: would the anterior bony beak blunt?

To investigate the remodeling morphology of subluxated osteotomy vertebra in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis after single-level closing-opening wedge osteotomy (COWO). Standing lateral radiographs were taken to evaluate sagittal parameters including lumbar lordosis (LL), C7 sagittal vertical axis (SVA), global kyphosis (GK), sacral slope (SS), and pelvic tilt (PT). Radiographic parameters of the osteotomy vertebra included osteotomized vertebra angle (OVA), sagittal translation (ST), anterior height (AH), posterior height (PH), and middle height (MH) of the osteotomy vertebrae. Furthermore, lateral projection area of the vertebral body was also measured to evaluate the remodeling of the osteotomy vertebrae. Sixty AS patients who underwent single-level lumbar COWO with a minimal 2-year follow-up were included. The cohort consisted of 54 males and 6 females with an average age of 36.6years. All patients were divided into two groups according to the development of vertebral subluxation (VS): 15 in VS group (ST ≥ 5mm), 45 in non-VS group (ST < 5mm). There was significant difference in the correction of GK, SVA, and the loss of correction of SVA between AS patients with and without VS. Significant difference in vertebra-related parameters regarding AH and OVA was found between VS group and non-VS group (P < 0.05). After COWO, new bone formation narrowing the gap and adaptive resorption of the anterior bony beak at the osteotomy level during follow-up was surprisingly favorable. However, the ability of spinal canal remodeling is limited in patients complicated with VS.

Clinical and radiographic benefits of skipping C7 instrumentation in posterior cervicothoracic fusion: a retrospective analysis.

BackgroundC7 instrumentation during posterior cervicothoracic fusion can be challenging because it requires additional work of either placing side connectors to a single rod or placing two rods. Our clinical observations suggested that skipping instrumentation at C7 in a multi-level posterior cervicothoracic fusion will result in minimal intraoperative complications and decreased blood-loss while still maintaining sagittal balance parameters of cervical fusion. The objective of this study is to determine the clinical and radiographic outcomes of skipping C7 instrumentation compared to instrumenting the C7 vertebra in posterior cervicothoracic fusion.MethodsThis is a retrospective chart review of 314 consecutive patients who underwent multilevel posterior cervical fusion (PCF) at our institution. Out of 314 patients, 19 were instrumented at C7 serving as the control group, while the remaining 295 patients were not. Evaluation of efficacy was based on intraoperative complications, operative time, estimated blood loss (EBL), significant long-term complications, and radiographic evidence of fusion.ResultsSkipping the C7 level resulted in a significant reduction in EBL (488±576 vs. 822±1,137; P=0.007); however, operative time was similar between groups (174±95 vs. 184±86 minutes; P=0.844). Complications were minimal in both groups and not statistically significant. Radiographic analysis revealed C7 bridge patients had a significantly increased postoperative sagittal vertical axis (SVA) (29.3±13.1 vs. 20.2±3.1 mm; P=0.008); however, there was no significant difference between groups in SVA correction (−0.3±16.2 vs. −16.1±16.0 mm; P=0.867), T1 slope correction (3.4°±9.9° vs. 3.2°±5.5°; P=0.127), or cervical cobb angle correction (−5.7°±14.2° vs. −7.0°±12.2°; P=0.519). There were no significant long-term complications in either group.ConclusionsSkipping instrumentation at C7 in a multilevel posterior cervicothoracic fusion is associated with significantly reduced operative blood loss without loss of radiographic correction. This study demonstrates the clinical benefits of skipping C7 instrumentation in posterior cervicothoracic fusion with maintenance of radiographic correction parameters.

Modified Ondra's Formula to Predict Post-Op SVA after Lumbar PSO: A Preliminary Report Verified by Simulated Post-op Images Via Surgimap Software.

This study aimed to introduce a new mathematical formula to predict sagittal vertical axis (SVA) changes after lumbar pedicle subtraction osteotomy (PSO). This cross-sectional study included 43 patients. Lateral full spinal radiographs were exported from Picture Archiving and Communicating Systemand imported to Surgimap (NemarisInc,New York, NY, version 2.3.1.1) software for PSO simulation. Regression analysis was done on the first 16 cases to find a constant variable (K) in the proposed formula. PSOs of 15°, 20°,25°, 30°, and 35°were simulated at L3,L4, and L5 for each patient, and the simulated postoperative SVAs were compared to predict postoperative SVA. Paired T-Test, Spearman test, and analysis of variance were applied to analyze the results. The Statistical Package for the Social Sciences software (Version 24.0) was used for the statistical analysis. Postoperative SVA was different in terms of PSO level and degree, with a mean of 74.87±37.88, 66.12±38.33, and 56.95±38.53 at 15°; 61.76±36.68, 50.13±37.32, and 43.03±36.67 at 20°; 48.61±35.60, 39.13±35.35, and 43.18±31.56 at 25°; and 37.73±33.78, 42.38±28.76, and 44.81±16.85 at 30° for L3, L4, and L5, respectively (P 0.05). The mean difference between the predicted SVA using the formula and the SVA simulated using Surgimap software was 2.37, 2.09, and 0.47 mm atL3, L4, andL5 levels, respectively. The mathematical formula was highly predictive for postoperative simulated SVA values in all three vertebral levels (L3-L5) (P 0.05). Additionally, a strong relationship was found between the vertebral level and the amount of SVA correction (Spearman correlation: 0.7-0.9). The mathematical formula is an accurate predictor of postoperative SVA and is helpful in PSO surgical planning. However, future studies are recommended to verify its accuracy in a clinical setting.

Are the Arbeitsgemeinschaft Für Osteosynthesefragen (AO) Principles for Long Bone Fractures Applicable to 3-Column Osteotomy to Reduce Rod Fracture Rates?

The aim was to determine whether applying Arbeitsgemeinschaft für Osteosynthesefragen (AO) principles for external fixation of long bone fracture to patients with a 3-column osteotomy (3CO) would be associated with reduced rod fracture (RF) rates. AO dictate principles to follow when fixating long bone fractures: (1) decrease bone-rod distance; (2) increase the number of connecting rods; (3) increase the diameter of rods; (4) increase the working length of screws; (5) use multiaxial fixation. We hypothesized that applying these principles to patients undergoing a 3CO reduces the rate of RF. Patients were categorized as having RF versus no rod fracture (non-RF). Details on location and type of instrumentation were collected. Dedicated software was used to calculate the distance between osteotomy site and adjacent pedicle screws, angle between screws and the distance between the osteotomy site and rod. Classic sagittal spinopelvic parameters were evaluated. The study included 170 patients (34=RF, 136=non-RF). There was no difference in age (P=0.224), sagittal vertical axis correction (P=0.287), or lumbar lordosis correction (P=0.36). There was no difference in number of screws cephalad (P=0.62) or caudal (P=0.31) to 3CO site. There was a lower rate of RF for patients with >2 rods versus 2 rods (P<0.001). Patients with multiplanar rod fixation had a lower rod fracture rate (P=0.01). For patients with only 2 rods (N=68), the non-RF cohort had adjacent screws that trended to have less angulation to each other (P=0.06) and adjacent screws that had a larger working length (P=0.03). A portion of AO principles can be applied to 3CO to reduce RF rates. Placing more rods around a 3CO site, placing rods in multiple planes, and placing adjacent screws with a larger working length around the 3CO site is associated with lower RF rates.

Global Sagittal Alignment and Clinical Outcomes after 1-3 Short-Segment Lumbar Fusion in Degenerative Spinal Diseases.

Study DesignLevel III retrospective study.PurposeWe investigated the impact of short-segment lumbar fusion on the restoration of global sagittal alignment and the correlations between spino-pelvic parameters and clinical outcomes.Overview of LiteratureSagittal imbalance leads to energy consumption and pain in maintaining a standing position. For adult spinal deformity, it is critical to create optimal lumbar lordosis (LL) in order to achieve restoration of sagittal imbalance. However, surgeons do not pay attention to correcting LL in short-segment lumbar fusion.MethodsA total of 69 patients with transforaminal lumbar interbody fusion (TLIF) for degenerative spinal disease were evaluated with a minimum 2-year follow-up. All patients underwent TLIF with hyper-lordotic angle cages to achieve higher LL. Radiological spino-pelvic parameters including sagittal vertical axis (SVA) and clinical outcomes using the Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) were evaluated.ResultsThe average LL was 35.8°±9.9° before surgery, 42.3°±9.3° 1 year after surgery, and 40.3°±10.2° 2 years after surgery (p<0.01). The average SVA was 43.1±6.2 mm before surgery, 21.2±4.9 mm 1 year after surgery, and 34.0±4.7 mm 2 years after surgery (p<0.01). The average LL and SVA improved in two- or three-segment fusion, but not in one-segment fusion. The correlation between ΔLL and ΔSVA was significant in all segment fusions. The correlation between ΔLL and ΔSVA was more significant at the L4–5 and L5–S1 segments than at L3–4. ODI was significantly correlated with SVA (p<0.05). NRS showed no correlation with the radiological parameters.ConclusionsTwo- or three-segment lumbar fusion using hyper-lordotic angle cages improved LL and SVA. A significant correlation between the correction of LL and SVA was found. Higher correction of LL using hyper-lordotic angle cages is thus recommended in short-segment lumbar fusion, since postoperative improvements of SVA significantly affect clinical outcomes.

Strategies for prevention of rod fracture in adult spinal deformity: cobalt chrome rod, accessory rod technique, and lateral lumbar interbody fusion.

Restoring the proper sagittal alignment in adult spinal deformity (ASD) can improve radiological and clinical outcomes, but pseudarthrosis including rod fracture (RF) is a common problematic complication. The purpose of this study was to analyze the methods for reducing the incidence of RF in deformity correction of ASD. The authors retrospectively selected 178 consecutive patients (mean age 70.8 years) with lumbar degenerative kyphosis (LDK) who underwent deformity correction with a minimum 2-year follow-up. Patients were classified into the non-RF group (n = 131) and the RF group (n = 47). For predicting the crucial factors of RF, patient factors, radiographic parameters, and surgical factors were analyzed. The overall incidence of RF was 26% (47/178 cases), occurring in 42% (42/100 cases) of pedicle subtraction osteotomy (PSO), 7% (5/67 cases) of lateral lumbar interbody fusion (LLIF) with posterior column osteotomy, 18% (23/129 cases) of cobalt chrome rods, 49% (24/49 cases) of titanium alloy rods, 6% (2/36 cases) placed with the accessory rod technique, and 32% (45/142 cases) placed with the 2-rod technique. There were no significant differences in the incidence of RF regarding patient factors between two groups. While both groups showed severe sagittal imbalance before operation, lumbar lordosis (LL) was more kyphotic and pelvic incidence (PI) minus LL (PI-LL) mismatch was greater in the RF group (p < 0.05). Postoperatively, while LL and PI-LL did not show significant differences between the two groups, LL and sagittal vertical axis correction were greater in the RF group (p < 0.05). Nonetheless, at the last follow-up, the two groups did not show significant differences in radiographic parameters except thoracolumbar junctional angles. As for surgical factors, use of the cobalt chrome rod and the accessory rod technique was significantly greater in the non-RF group (p < 0.05). As for the correction method, PSO was associated with more RFs than the other correction methods, including LLIF (p < 0.05). By logistic regression analysis, PSO, preoperative PI-LL mismatch, and the accessory rod technique were crucial factors for RF. Greater preoperative sagittal spinopelvic malalignment including preoperative PI-LL mismatch was the crucial risk factor for RF in LDK patients 65 years or older. For restoring and maintaining sagittal alignment, use of the cobalt chrome rod, accessory rod technique, or LLIF was shown to be effective for reducing RF in ASD surgery.

The Effect of Anterior Cervical Discectomy and Fusion on Cervical Sagittal Vertical Axis and Lordosis with Minimum 2-Year Follow-Up

Anterior cervical discectomy and fusion (ACDF) can induce lordosis and improve cervical sagittal vertical axis (SVA), but multilevel ACDF may inadvertently increase cervical SVA because of insufficient lordosis induction. Patients who underwent 1-, 2-, or ≥3-level ACDF in the subaxial spine with minimum 2-year follow up were retrospectively studied. C2-C7 Cobb angle (lordosis), cervical SVA, and T1 slope were measured preoperatively, immediately postoperatively, and at last follow-up. Inclusion criteria were met by 127 patients. There were no differences in baseline demographics among 1-, 2-, and ≥3-level ACDF groups. Mean follow-up was 43.7 months (range, 24-142 months). Increase of cervical SVA immediately postoperatively was 1.94 mm,-1.44 mm, and 7.25 mm for 1-, 2-, and ≥3-level ACDF (P= 0.041) and at last follow-up was 2.97 mm, 0.70 mm, and 9.32 mm for 1-, 2-, and ≥3-level ACDF (P= 0.026). At last follow-up, 2-level ACDF patients had the greatest decrease in T1 slope (-0.43°) compared with increase of 2.71° for 1-level and 2.84° for ≥3-level patients (P= 0.028). In all 3 groups, segmental (ACDF levels) lordosis, cervical SVA, and T1 slope did not decrease from immediate postoperative to last follow-up. Only 2-level ACDF maintained C2-7 lordosis (2.16°) compared with loss of lordosis in 1-level (-0.84°) and ≥3-level (-2.00°) ACDF (P= 0.008) at last follow-up. Linear regression analysis showed that T1 slope had no relationship with correction of cervical SVA (P= 0.5310) but had a significant correlation with Cobb angle loss of C2-C7 lordosis (P= 0.0016). Compared with 1- and 2-level ACDF, ≥3-level ACDF resulted in significant increase of cervical SVA and loss of overall lordosis. Compared with 1- and ≥3-level ACDF, 2-level ACDF had the greatest ability to maintain lordosis. T1 slope had a significant correlation with loss of C2-C7 lordosis after ACDF.

Impact of body mass index on surgical outcomes and complications in adult spinal deformity

BackgroundSeveral studies have reported that overweightness and obesity are associated with higher complication rates in lumbar spine surgery. However, little is known about the effect of obesity on postoperative complications in adult spinal deformity (ASD) surgery, especially in the elderly. This study aimed to examine the effect of body mass index (BMI) on surgical outcomes and postoperative complications in elderly ASD patients undergoing surgical correction in Japan. MethodsWe conducted a retrospective, multicenter, observational study of 234 consecutive patients diagnosed with ASD who underwent corrective surgery. Patients were divided into two groups according to BMI, BMI <25 (153 patients, mean age 71.9 years) and BMI ≥ 25 (overweight/obese, 81 patients, mean age 73.3 years). Radiographic results and perioperative complications were compared between the two groups. ResultsSurgical complications occurred in approximately 20% of patients in each group; complications did not significantly differ between the two groups. A greater proportion of patients in the BMI ≥ 25 group experienced mechanical failure and DJK, although the difference was not significant. Preoperative mean lumbar lordosis (LL), pelvic incidence (PI) minus LL, sacral slope (SS) and sagittal vertical axis (SVA) were similar in the BMI < 25 and BMI ≥ 25 groups. However, the BMI ≥25 group had lower mean LL (p = 0.015) and higher PI minus LL (p = 0.09) postoperatively. The BMI ≥25 groups also had significantly smaller LL (p = 0.026), smaller SS (p = 0.049) and higher SVA (p = 0.041) at the final follow-up, compared to the BMI < 25 group. ConclusionsIn the present study, no difference in medical or surgical complications after ASD surgery was found between overweight/obese patients (BMI ≥ 25) and those with BMI < 25. However, correction of LL and SVA was smaller in patients with overweight/obese patients.

Recurrence of proximal junctional kyphosis after revision surgery for symptomatic proximal junctional kyphosis in patients with adult spinal deformity: incidence, risk factors, and outcomes.

Although proximal junctional kyphosis (PJK) is common after long spinal fusion, the outcomes of revision surgery for symptomatic PJK are unclear. Our aim was to assess the outcomes of revision surgery for symptomatic PJK in patients with adult spinal deformity and elucidate the incidence and risk factors for recurrent PJK (rePJK). We evaluated standing radiographs and health-related quality of life (HRQOL) in patients who underwent revision surgery for symptomatic PJK with at least 2-year follow-up. Patients were assigned to the non-rePJK or rePJK group according to PJK recurrence. Thirty-nine consecutive patients (mean age, 63 ± 11years; 24 women) met the inclusion criteria. RePJK occurred in 12 patients (31%). There were significant differences in the following parameters between groups (non-rePJK vs. rePJK): initial proximal junctional sagittal Cobb angle (PJA) (26.6° vs. 35.6°), thoracic kyphosis (TK) (38.6° vs. 52.8°), and sagittal vertical axis (SVA) (9.3 vs. 15.9cm), and pre- to postoperative SVA decrease (6.1 vs. 12.2cm). Significant risk factors for rePJK were initial PJA > 40°, preoperative TK > 60°, preoperative SVA > 10.0cm, correction of TK > 15°, and correction of SVA > 5.0cm. HRQOL scores improved significantly; however, postoperative SRS-22r activity scores were significantly worse in the rePJK group vs the non-rePJK group. The incidence of rePJK was 31%. Risk factors for rePJK were large initial PJA, high preoperative TK and SVA, and greater correction of TK and SVA. HRQOL did not differ significantly between patients with vs without rePJK, except immediate postoperative SRS-22r activity scores. III.

Outcomes of Oblique Lateral Interbody Fusion for Adult Spinal Deformity: A Systematic Review and Meta-Analysis.

Study Design:A systematic review and meta-analysis.Objectives:To evaluate clinical and radiographic outcomes, and perioperative complications of oblique lateral interbody fusion (OLIF) for adult spinal deformity (ASD).Methods:We performed a systematic review and meta-analysis of related studies reporting outcomes of OLIF for ASD. The clinical outcomes were assessed by visual analogue scale (VAS) and Oswestry Disability Index (ODI). The radiographic parameters were evaluated by sagittal vertical axis (SVA), pelvic tilt (PT), sacral slope (SS), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence-lumbar lordosis (PI-LL), Cobb angle and fusion rate. A random effects model and 95% confidence intervals (CI) were performed to investigate the results.Results:A total of 16 studies involving 519 patients were included in the present study. The mean difference of VAS-back score, VAS-leg score and ODI score before and after surgery was 5.1, 5.0 and 32.3 respectively. The mean correction of LL was 20.6°, with an average of 6.9° per level and the mean correction of Cobb was 16.4°, with an average of 4.7° per level. The mean correction of SVA, PT, SS, TK and PI-LL was 59.3 mm, 11.7°, 6.9°, 9.4° and 20.6° respectively. The mean fusion rate was 94.1%. The incidence of intraoperative and postoperative complications was 4.9% and 29.6% respectively.Conclusions:OLIF is an effective and safe surgery method in the treatment of mild or moderate ASD and it has advantages in less intraoperative blood loss and lower perioperative complications.

Proximal Junctional Kyphosis in Degenerative Sagittal Deformity After Under- and Overcorrection of Lumbar Lordosis: Does Overcorrection of Lumbar Lordosis Instigate PJK?

Retrospective study. To analyze proximal junctional kyphosis (PJK) occurrence and surgical outcomes according to degree of lumbar lordosis (LL) correction relative to pelvic incidence (PI). In addition, risk factors of PJK including LL and sagittal vertical axis (SVA) correction were investigated. PJK is a common complication after adult spinal deformity surgery, and many factors are known to be associated with PJK. However, the effect of degree of LL correction on PJK occurrence is not fully understood. Eighty-three degenerative sagittal imbalance patients treated with deformity correction and long instrumented fusion to the sacrum with a minimum follow-up of 2 years were studied. Patients were divided into three groups according to their postoperative LL angle relative to PI using the SRS-Schwab classification: Group A (undercorrection, PI-LL> 10°), Group B (ideal correction, -10°<PI-LL≤10°), and Group C (overcorrection, PI-LL≤-10°). Prevalence, classification, and period of PJK occurrence were compared, and radiographic and clinical outcomes were analyzed. In addition, risk factors for PJK were evaluated. Overall PJK prevalence was 36.1% (30/83), and ratio of optimal SVA at postoperative and last follow-up were significantly higher in Group C (P < 0.001, P < 0.001). Nevertheless, there was no significant difference in PJK prevalence among three groups (40% vs. 37.5% vs. 34.1%; P = 0.907). Group C had better clinical outcomes (last follow-up ODI, VAS of LBP) than Group A (10.0 vs. 18.4; P < 0.001 and 1.5 vs. 4.0; P < 0.001). The increases in LL or SVA correction degree were not associated with PJK occurrence (P = 0.304, P = 0.201). Overcorrection showed good surgical outcomes without increasing PJK prevalence. Degrees of LL and SVA correction do not act as risk factors for PJK. Therefore, in adult spinal deformity patients, LL correction greater than PI may be a good choice that can result in better clinical outcomes without increasing risk of PJK. 4.

Multiple-rod constructs in adult spinal deformity surgery for pelvic-fixated long instrumentations: an integral matched cohort analysis.

Multiple-rod constructs (Multi-Rod: extra rods for additional pillar support) are occasionally used in adult spinal deformity (ASD) surgery. We aimed to compare and analyze the general outcome of multi-rod constructs with a matched two-rod cohort, to better understand the differences and the similitudes. This is a retrospective matched cohort study including patients with ASD that underwent surgical correction with long posterior instrumentation (more than five levels), pelvic fixation and a minimum 1-year follow-up. Matching was considered with demographical data, preoperative radiographical parameters, preoperative clinical status [health-related quality-of-life (HRQoL) scores] and surgical characteristics (anterior fusion, decompression, rod material, osteotomies). Postoperative radiographical and clinical parameters, as well as complications, were obtained. Univariate and multivariate analysis was performed regarding postoperative improvement, group variables comparison and parameters correlation. Thirty-three patients with multi-rod construct and 33 matched with a two-rod construct were selected from a database with 346 ASD-operated patients. Both groups had a significant improvement with surgical management in the radiographical and HRQoL parameters (p < 0.001). Differences between groups for the postoperative radiographical, clinical and perioperative parameters were not significant. Rod breakage was more frequent in the two-rod group (8 vs 4, p = 0.089), as well as the respective revision surgery for those cases (6 vs 1 p = 0.046). Risk factors related to revision surgery were greater kyphosis correction (p = 0.001), longer instrumentation (p = 0.037) and greater sagittal vertical axis correction (p = 0.049). No major disadvantage on the use of multi-rod construct was identified. This supports the benefit of using multi-rod constructs to avoid implant failure. These slides can be retrieved under Electronic Supplementary Material.

Hip involvement negatively impact the postoperative radiographic outcomes after lumbar pedicle subtraction osteotomy in ankylosing spondylitis patients with thoracolumbar kyphosis-a retrospective study

Background: Lumbar pedicle subtraction osteotomy (PSO) can significantly correct thoracic kyphosis and relieve the compensatory pelvic backward tilt. However, hip involvement occurred in some advanced AS patients could restrict the rotation of the pelvis around the femoral heads, which may affect the postoperative radiographic outcomes after lumbar PSO. The aim of the study is to identify whether hip involvement will negatively impact the postoperative radiographic outcomes after lumbar PSO in AS patients with thoracolumbar kyphosis. Method s: From March 2009 to June 2013, a total of 44 consecutive AS patients with thoracolumbar kyphosis undergoing one-level lumbar PSO were retrospectively reviewed. All the patients had more than 2-year follow-up. Hip involvement was evaluated based on the Bath ankylosing spondylitis radiology index-hip (BASRI-hip) and defined by a score of at least 2. All patients were divided into group A (patients without hip involvement) and group B (patients with hip involvement). Radiographical measurements included sagittal vertical axis (SVA), global kyphosis (GK), thoracic kyphosis (TK), local kyphosis (LK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). Results : The preoperative SVA and PT was not significantly different between group A and group B (SVA: 14.0 ± 6.3cm vs. 14.7 ± 6.0cm, P &gt; 0.05; PT: 36.8° ± 7.1° vs. 37.3° ± 7.7°, P &gt; 0.05), and both groups had similar magnitudes of kyphosis corrections (LK correction: 44.9° ± 4.9° vs. 44.2° ± 8.3°, P &gt; 0.05). However, group B had significantly larger SVA and PT than group A (SVA: 7.6 ± 4.5cm vs 3.5 ± 3.4cm, P &lt; 0.05; PT: 28.1° ± 8.6° vs. 19.0° ± 8.0°, P &lt; 0.05) at the last follow-up. Conclusion: In AS patients with thoracolumbar kyphosis, hip involvement lead to insufficient correction of SVA and PT after lumbar PSO, which negatively impact postoperative radiographic outcomes. For these patients, additional osteotomies may be recommended for satisfactory correction outcomes. Key words: ankylosing spondylitis, thoracolumbar kyphosis, pedicle subtraction osteotomy, hip involvement

The case for T2 pedicle subtraction osteotomy in the surgical treatment of rigid cervicothoracic deformity.

Rigid cervicothoracic kyphotic deformity (CTKD) remains a difficult pathology to treat, especially in the setting of prior cervical instrumentation and fusion. CTKD may result in chronic neck pain, difficulty maintaining horizontal gaze, and myelopathy. Prior studies have advocated for the use of C7 or T1 pedicle subtraction osteotomies (PSOs). However, these surgeries are fraught with danger and, most significantly, place the C7, C8, and/or T1 nerve roots at risk. The authors retrospectively reviewed their experience with performing T2 PSO for the correction of rigid CTKD. Demographics collected included age, sex, details of prior cervical surgery, and coexisting conditions. Perioperative variables included levels decompressed, levels instrumented, estimated blood loss, length of surgery, length of stay, complications from surgery, and length of follow-up. Radiographic measurements included C2-7 sagittal vertical axis (SVA) correction, and changes in the cervicothoracic Cobb angle, lumbar lordosis, and C2-S1 SVA. Four male patients were identified (age range 55-72 years). Three patients had undergone prior posterior cervical laminectomy and instrumented fusion and developed postsurgical kyphosis. All patients underwent T2 PSO: 2 patients received instrumentation at C2-T4, and 2 patients received instrumentation at C2-T5. The median C2-7 SVA correction was 3.85 cm (range 2.9-5.3 cm). The sagittal Cobb angle correction ranged from 27.8° to 37.6°. Notably, there were no neurological complications. T2 PSO is a powerful correction technique for the treatment of rigid CTKD. Compared with C7 or T1 PSO, there is decreased risk of injury to intrinsic hand muscle innervators, and there is virtually no risk of vertebral artery injury. Laminectomy may also be safer, as there is less (or no) scar tissue from prior surgeries. Correction at this distal level may allow for a greater sagittal correction. The authors are optimistic that these findings will be corroborated in larger cohorts examining this challenging clinical entity.

Psychological Changes and Employment Outcomes After Kyphosis Correction in Patients With Ankylosing Spondylitis.

A retrospective study. To evaluate the psychological changes and employment outcomes following corrective osteotomy in patients with ankylosing spondylitis (AS). To date, no study has investigated the changes in psychological status and subsequent improvement in employment outcome after correction of kyphotic deformities in patients with AS. This study included 48 patients with AS who underwent corrective osteotomy for severe kyphotic deformity. Sagittal alignment was assessed radiographically. Clinical status was evaluated using the Short Form-36 Health Survey, psychological status was evaluated using the Hospital Anxiety and Depression Scale (HADS), and employment outcomes were assessed using the Lam Employment Absence and Productivity Scale (LEAPS). The degree of postoperative sagittal alignment correction was measured, and changes in clinical and employment outcomes and psychological status were evaluated. The relationship between the degree of sagittal alignment correction and each evaluation item was analyzed. Following postoperative sagittal alignment correction, all patients could stand erect and look straight. Significant improvements were observed in the clinical and employment outcomes, as well as in patients' psychological status. The degree of sagittal vertical axis correction was significantly correlated with the HADS depression and the LEAPS total scores. The degree of correction of the chin-brow vertical angle was significantly correlated with the Short Form-36 mental health score, the HADS depression and anxiety scores, and the LEAPS total and productivity subscores. Notably, the improvement in the HADS depression score was significantly correlated with the LEAPS total score. This study demonstrated the psychological changes and subsequent improvement in employment outcomes after corrective osteotomy in patients with AS. The degree of sagittal alignment correction was correlated with improvements in psychological status and employment outcomes. 4.