A Comprehensive Review of Complication Rates After Surgery for Adult Deformity: A Reference for Informed Consent

Independent Risk Factors of Proximal Junctional Kyphosis with Vertebral Fracture After Spinal Long Fusion: Survivorship Analysis of Adult Spinal Deformity Surgery Patients

OBJECTIVE

This study aimed to identify risk factors for postoperative proximal junctional kyphosis (PJK) with vertebral fracture in adult spinal deformity (ASD) patients. We performed a survival analysis considering various factors, including osteoporosis.

METHODS

This single-center retrospective study included 101 ASD patients (mean age: 67.2 years, mean follow-up: 8.1 years). We included patients aged ≥50 years with abnormal radiographic variables undergoing corrective long spinal fusion. The main outcome measure was PJK with vertebral fracture, analyzed based on patient data, radiographic measurements, sagittal parameters, bone mineral density, and osteoporosis medication.

RESULTS

PJK occurred in 37.6% of patients, with vertebral fracture type 2 accounting for 65% of these cases. Kaplan-Meier analysis indicated a median PJK-free survival time of 60.7 months. Existing vertebral fracture (grade 1 or higher or grade 2 or higher) was a significant risk factor for PJK with vertebral fracture, with hazard ratios of 4.58 and 5.61, respectively. The onset time of PJK with vertebral fracture was 1.5 months postoperatively, with 44% of these cases occurring within 1 month and 64% within 2 months.

CONCLUSIONS

PJK with vertebral fracture affected 25% of ASD patients, emphasizing the importance of osteoporosis evaluation. Existing vertebral fracture emerged as a significant independent risk factor, surpassing bone mineral density. This study provides valuable insights for spine surgeons, highlighting the need to provide osteoporosis treatment and emphasize potential postoperative complications during discussions with patients.

Pedicle Subtraction Osteotomy Versus Multilevel Anterior Lumbar Interbody Fusion and Lateral Lumbar Interbody Fusion in the Treatment of Adult Spinal Deformity: Trends, Outcomes, and Cost

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the outcomes of pedicle subtraction osteotomy (PSO) with multilevel anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) in posterior long-segment fusion.

BACKGROUND

PSO and ALIF/LLIF are 2 techniques used to restore lumbar lordosis and correct sagittal alignment, with each holding its unique advantages and disadvantages. As there are situations where both techniques can be employed, it is important to compare the risks and benefits of both.

PATIENTS AND METHODS

Patients aged 18 years or older who underwent PSO or multilevel ALIF/LLIF with posterior fusion of 7-12 levels and pelvic fixation were identified. 1:1 propensity score was used to match PSO and ALIF/LLIF cohorts for age, sex, and relevant comorbidities, including smoking status. Logistic regression was used to compare medical and surgical outcomes. Trends and costs were generated for both groups as well.

RESULTS

ALIF/LLIF utilization in posterior long fusion has been steadily increasing since 2010, whereas PSO utilization has significantly dropped since 2017. PSO was associated with an increased risk of durotomy ( P < 0.001) and neurological injury ( P = 0.018). ALIF/LLIF was associated with increased rates of postoperative radiculopathy ( P = 0.005). Patients who underwent PSO had higher rates of pseudarthrosis within 1 and 2 years ( P = 0.015; P = 0.010), 1-year hardware failure ( P = 0.028), and 2-year reinsertion of instrumentation ( P = 0.009). Reoperation rates for both approaches were not statistically different at any time point throughout the 5-year period. In addition, there were no significant differences in both procedural and 90-day postoperative costs.

CONCLUSIONS

PSO was associated with higher rates of surgical complications compared with anterior approaches. However, there was no significant difference in overall reoperation rates. Spine surgeons should select the optimal technique for a given patient and the type of lordotic correction required.

Artificial Intelligence in Spine Surgery

The amount and quality of data being used in our everyday lives continue to advance in an unprecedented pace. This digital revolution has permeated healthcare, specifically spine surgery, allowing for very advanced and complex computational analytics, such as artificial intelligence (AI) and machine learning (ML). The integration of these methods into clinical practice has just begun, and the following review article will describe AI/ML, demonstrate how it has been applied in adult spinal deformity surgery, and show its potential to improve patient care touching on future directions.

Perioperative Blindness in Spine Surgery: A Scoping Literature Review

Perioperative vision loss (POVL) is a devastating surgical complication that impacts both the recovery from surgery and quality of life, most commonly occurring after spine surgery. With rates of spine surgery dramatically increasing, the prevalence of POVL will increase proportionately. This scoping review aims to aggregate the literature pertinent to POVL in spine surgery and consolidate recommendations and preventative measures to reduce the risk of POVL. There are several causes of POVL, and the main contribution following spine surgery is ischemic optic neuropathy (ION). Vision loss often manifests immediately following surgery and is irreversible and severe. Diffusion weighted imaging has recently surfaced as a diagnostic tool to identify ION. There are no effective treatments; therefore, risk stratification for counseling and prevention are vital. Patients undergoing prone surgery of long duration and/or with significant expected blood loss are at greatest risk. Future research is necessary to develop effective treatments.

Predicting major complications and discharge disposition after adult spinal deformity surgery

BACKGROUND CONTEXT

Several spine-specific comorbidity indices are available to help risk-stratify patients before they undergo invasive spine procedures. Studies of patients with adult spinal deformity (ASD) typically use the Charlson Comorbidity Index (CCI), which is not specific to spine patients.

PURPOSE

To compare the CCI with the Seattle Spine Score (SSS), the Adult Spinal Deformity-Comorbidity Score (ASD-CS), and the Modified 5-Item Frailty Index (mFI-5) and identify which tool more accurately predicted major perioperative complications and discharge disposition after ASD surgery.

STUDY DESIGN/SETTING

Retrospective review.

PATIENT SAMPLE

Patients with ASD who underwent spinal arthrodesis of at least four levels at a single institution.

OUTCOME MEASURES

Self-reported measures include SSS, ASD-CS, and mFI-5. Functional measures include the CCI.

METHODS

We retrospectively reviewed records of 164 patients with ASD who underwent spinal arthrodesis of ≥ four levels from January 2008 to February 2018 at our U.S. academic tertiary care center and who had available Oswestry Disability Index values. To assess the predictive ability of the comorbidity indices, we created five multivariable logistic regression models, with the presence of major complications and discharge disposition (home or inpatient rehabilitation) as the primary outcome variables. The base model used validated demographic and surgical factors that were predictors of complications and outcomes in those with ASD and within the broader spinal literature. The other four models used the base model along with one of the four indices. The predictive ability of each model was compared using goodness-of-fit testing, with higher pseudo-R2 values and lower Akaike information criteria (AIC) values indicating better model fit.

RESULTS

Thirty-one patients (19%) experienced major perioperative complications, and 68 (42%) were discharged to inpatient rehabilitation facilities (vs home). The model using the SSS had the highest pseudo-R2 value and lowest AIC value for both major complications and discharge disposition. The mFI-5 had a similar predictive ability. The models using the CCI and ASD-CS were weaker predictors.

CONCLUSIONS

Compared with the CCI and the ASD-CS, the SSS and the mFI-5 were strong predictors of major complications and discharge disposition after ASD surgery. These results suggest that the SSS and the mFI-5 are preferable to the CCI for clinical risk stratification and outcomes research in patients undergoing ASD surgery.

Complications in endoscopic spine surgery: a systematic review

PURPOSE

This systematic review aims to investigate the complication rate of endoscopic spine surgeries, stratifying them by technique, district and kind of procedure performed.

METHODS

This study was conducted according to the PRISMA statement. The literature search was conducted in MEDLINE, CINAHL, EMBASE, Cochrane Register, OTseeker and ScienceDirect database. Types of studies included were observational studies (cohort studies, case-control studies and case series) and randomised or quasi-randomised clinical with human subjects. No restrictions on publication year were applied. Repeated articles, reviews, expert's comments, congress abstracts, technical notes and articles not in English were excluded. Several data were extracted from the articles. In particular, data of perioperative (≤ 3 months) and late (> 3 months) complications were collected and grouped according to: (1) surgical technique [uniportal full-endoscopic spine surgery (UESS) or unilateral biportal endoscopic spine surgery (UBESS)]; (2) spinal district treated [cervical, thoracic or lumbar] and (3) type of procedure [discectomy/decompression or fusion]. Complication analysis was performed in subgroups with at least 100 patients to have clinically meaningful statistical validity.

RESULTS

A total of 117 full-text articles were assessed for eligibility. Of the 117 records included, 95 focused their research on UESS (14 LOE V, 33 LOE IV, 43 LOE III and five LOE II) and 23 on UBESS (three LOE V, eight LOE IV, 10 LOE III and two LOE II). A total of 20,020 patients were extracted to investigate the incidence of different perioperative and late complications, 10,405 for UESS and 9615 for UBESS.

CONCLUSION

The present study summarises the complications reported in the literature for spinal endoscopic procedures. On the one hand, the most relevant described were perioperative complications (transient neurological deficit, dural tear and dysesthesia) that are especially meaningful for endoscopic discectomy and decompression. On the other hand, late complications, such as mechanical implant failure, are more common in endoscopic interbody fusion.

LEVEL OF EVIDENCE

I.

Finite Element Modeling for Biomechanical Comparisons of Multilevel Transforaminal, Posterior, and Lateral Lumbar Approaches to Interbody Fusion Augmented with Posterior Instrumentation

OBJECTIVE

Verifying the intervertebral stability of each intervertebral fusion procedure, including transforaminal, posterior, and lateral lumbar interbody fusion (TLIF, PLIF, and LLIF, respectively), and the ratio of stress on the rods and pedicle screws during initial fixation may help select a fixation procedure that reduces the risk of mechanical complications, including rod fracture and screw loosening. Thus, we aimed to assess whether these procedures could prevent mechanical complications.

METHODS

Using the finite element method (FEM), we designed 4 surgical models constructed from L2-5 as follows: posterior lumbar fusion (PLF), TLIF, PLIF, and LLIF models. Bilateral rods and each pedicle screw stress were tracked and calculated as Von Mises stress (VMS) for comparison among the PLF and other 3 interbody fusion models during flexion, extension, and side-bending movements.

RESULTS

The lowest rod VMS was LLIF, followed by PLIF, TLIF, and PLF in flexion and side bending movements. Compared with PLF, intervertebral fixation significantly reduced stress on the rods. No remarkable differences were observed in extension movements in each surgical procedure. A tendency for higher pedicle screw VMS was noted at the proximal and distal ends of the fixation ranges, including L2 and L5 screws for each procedure in all motions. Intervertebral fixation significantly reduced stress on the L2 and L5 screws, particularly in LLIF.

CONCLUSIONS

Stress on the rods and pedicle screws in the LLIF model was the lowest compared with that induced by other intervertebral fusion procedures. Therefore, LLIF may reduce mechanical complications occurrence, including rod fracture and screw loosening.

Combined Anterior-Posterior vs. Posterior-Only Approach in Adult Spinal Deformity Surgery: Which Strategy Is Superior?

Introduction: Whether a combined anterior-posterior (AP) approach offers additional benefits over the posterior-only (P) approach in adult spinal deformity (ASD) surgery remains unknown. In a cohort of patients undergoing ASD surgery, we compared the combined AP vs. the P-only approach in: (1) preoperative/perioperative variables, (2) radiographic measurements, and (3) postoperative outcomes. Methods: A single-institution, retrospective cohort study was performed for patients undergoing ASD surgery from 2009 to 2021. Inclusion criteria were ≥5-level fusion, sagittal/coronal deformity, and 2-year follow-up. The primary exposure was the operative approach: a combined AP approach or P alone. Postoperative outcomes included mechanical complications, reoperation, and minimal clinically important difference (MCID), defined as 30% of patient-reported outcome measures (PROMs). Multivariable linear regression was controlled for age, BMI, and previous fusion. Results: Among 238 patients undergoing ASD surgery, 34 (14.3%) patients underwent the AP approach and 204 (85.7%) underwent the P-only approach. The AP group consisted mostly of anterior lumbar interbody fusion (ALIF) at L5/S1 (73.5%) and/or L4/L5 (38.0%). Preoperatively, the AP group had more previous fusions (64.7% vs. 28.9%, p < 0.001), higher pelvic tilt (PT) (29.6 ± 11.6° vs. 24.6 ± 11.4°, p = 0.037), higher T1 pelvic angle (T1PA) (31.8 ± 12.7° vs. 24.0 ± 13.9°, p = 0.003), less L1-S1 lordosis (-14.7 ± 28.4° vs. -24.3 ± 33.4°, p < 0.039), less L4-S1 lordosis (-25.4 ± 14.7° vs. 31.6 ± 15.5°, p = 0.042), and higher sagittal vertical axis (SVA) (102.6 ± 51.9 vs. 66.4 ± 71.2 mm, p = 0.005). Perioperatively, the AP approach had longer operative time (553.9 ± 177.4 vs. 397.4 ± 129.0 min, p < 0.001), more interbodies placed (100% vs. 17.6%, p < 0.001), and longer length of stay (8.4 ± 10.7 vs. 7.0 ± 9.6 days, p = 0.026). Radiographically, the AP group had more improvement in T1PA (13.4 ± 8.7° vs. 9.5 ± 8.6°, p = 0.005), L1-S1 lordosis (-14.3 ± 25.6° vs. -3.2 ± 20.2°, p < 0.001), L4-S1 lordosis (-4.7 ± 16.4° vs. 3.2 ± 13.7°, p = 0.008), and SVA (65.3 ± 44.8 vs. 44.8 ± 47.7 mm, p = 0.007). These outcomes remained statistically significant in the multivariable analysis controlling for age, BMI, and previous fusion. Postoperatively, no significant differences were found in mechanical complications, reoperations, or MCID of PROMs. Conclusions: Preoperatively, patients undergoing the combined anterior-posterior approach had higher PT, T1PA, and SVA and lower L1-S1 and L4-S1 lordosis than the posterior-only approach. Despite increased operative time and length of stay, the anterior-posterior approach provided greater sagittal correction without any difference in mechanical complications or PROMs.

Clinical and Radiologic Analysis of Minimally Invasive Anterior-Posterior Combined Surgery for Adult Spinal Deformity: Comparison of Oblique Lateral Interbody Fusion at L5/S1 (OLIF51) versus Transforaminal Interbody Fusion

Background and Objectives: Although adult spinal deformity (ASD) surgery brought about improvement in the quality of life of patients, it is accompanied by high invasiveness and several complications. Specifically, mechanical complications of rod fracture, instrumentation failures, and pseudarthrosis are still unsolved issues. To better improve these problems, oblique lateral interbody fusion at L5/S1 (OLIF51) was introduced in 2015 at my institution. The objective of this study was to compare the clinical and radiologic outcomes of anterior-posterior combined surgery for ASD between the use of OLIF51 and transforaminal interbody fusion (TLIF) at L5/S1. Materials and Methods: A total of 117 ASD patients received anterior-posterior correction surgeries either with the use of OLIF51 (35 patients) or L5/S1 TLIF (82 patients). In both groups, L1-5 OLIF and minimally invasive posterior procedures of hybrid or circumferential MIS were employed. The sagittal and coronal spinal alignment and spino-pelvic parameters were recorded preoperatively and at follow-up. The quality-of-life parameters and visual analogue scale were evaluated, as well as surgical complications at follow-up. Results: The average follow-up period was thirty months (13-84). The number of average fused segments was eight (4-12). The operation time and estimated blood loss were significantly lower in OLIF51 than in TLIF. The PI-LL mismatch, LLL, L5/S1 segmental lordosis, and L5 coronal tilt were significantly better in OLIF51 than TLIF. The complication rate was statistically equivalent between the two groups. Conclusions: The introduction of OLIF51 for adult spine deformity surgery led to a decrease in operation time and estimated blood loss, as well as improvement in sagittal and coronal correction compared to TLIF. The circumferential MIS correction and fusion with OLIF51 serve as an effective surgical modality which can be applied to many cases of adult spinal deformity.

Analysis of Personalized Interbody Implants in the Surgical Treatment of Adult Spinal Deformity

STUDY DESIGN

Multicenter cohort.

OBJECTIVES

A report from the International Spine Study Group (ISSG) noted that surgeons failed to achieve alignment goals in nearly two-thirds of 266 complex adult deformity surgery (CADS) cases. We assess whether personalized interbody spacers are associated with improved rates of achieving goal alignment following adult spinal deformity (ASD) surgery.

METHODS

ASD patients were included if their surgery utilized 3D-printed personalized interbody spacer(s) and they met ISSG CADS inclusion criteria. Planned alignment was personalized by the surgeon during interbody planning. Planned vs achieved alignment was assessed and compared with the ISSG CADS series that used stock interbodies.

RESULTS

For 65 patients with personalized interbodies, 62% were women, mean age was 70.3 years (SD = 8.3), mean instrumented levels was 9.9 (SD = 4.1), and the mean number of personalized interbodies per patient was 2.2 (SD = .8). Segmental alignment was achieved close to plan for levels with personalized interbodies, with mean difference between goal and achieved as follows: intervertebral lordosis = .9° (SD = 5.2°), intervertebral coronal angle = .1° (SD = 4.7°), and posterior disc height = -0.1 mm (SD = 2.3 mm). Achieved pelvic incidence-to-lumbar lordosis mismatch (PI-LL) correlated significantly with goal PI-LL (r = .668, P < .001). Compared with the ISSG CADS cohort, utilization of personalized interbodies resulted in significant improvement in achieving PI-LL <5° of plan (P = .046) and showed a significant reduction in cases with PI-LL >15° of plan (P = .012).

CONCLUSIONS

This study supports use of personalized interbodies as a means of better achieving goal segmental sagittal and coronal alignment and significantly improving achievement of goal PI-LL compared with stock devices.

Health-related quality of life 2 years after pedicle subtraction osteotomy for sagittal imbalance: a single-center experience of 65 patients

PURPOSE

Pedicle subtraction osteotomy (PSO) as an invasive procedure with high reoperation and complication rates in an often elderly population has often been questioned. The purpose of our study was to evaluate the impact of PSO for sagittal imbalance (SI) on patient-reported outcomes including self-reported satisfaction and health-related quality of life 2 years postoperatively.

METHODS

Consecutive patients who underwent correction of their spinal deformity by thoracolumbar PSO were assessed using self-reporting questionnaires 2 years postoperatively. Outcome was measured by visual analogue scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), and EQ-5D scores. Additionally, a Patient Satisfaction Index (PSI) rated in four grades (A: very satisfied to D: not satisfied), walking range, and the Timed Up and Go (TUG) Test were evaluated.

RESULTS

Sixty-five patients were included, and each parameter was assessed preoperatively and 24 months postoperatively. The intervention led to significant improvements in back pain (8.1 ± 1.2 vs. 2.9 ± 1.9; p < 0.001), as well as ODI scores (57.7 ± 13.9 vs. 32.6 ± 18.9; p < 0.001), walking range (589 ± 1676 m vs. 3265 ± 3405 m; p < 0.001), and TUG (19.2 s vs. 9.7 s; p < 0.05). 90.7% of patients (n = 59/65) reported a PSI grade "A" or "B" 24 months postoperatively.

CONCLUSION

Patient satisfaction 24 months after PSO for SI is high. Quality of life improved significantly by restoring sagittal balance.

Do peri-operative parathyroid hormone (PTH) analogues improve bone density and decrease mechanical complications in spinal deformity correction?-a minimum 2-year radiological study measuring Hounsfield units

OBJECTIVE

To delineate whether use of a PTH analogue in the 1-year peri-operative period improves lumbar bone density.

METHODS

A prospectively collected data registry of 254 patients who underwent CMIS correction of ASD (Cobb angle > 20 or SVA > 50 mm or (PI-LL) > 10) from Jan 2011 to Jan 2020 was analysed. Patients who were placed on PTH analogues for one year in conjunction with surgery were included in the study. Ultimately, 41 patients who had pre- and two-year post-operative CT scans for review were included in this study. Hounsfield units were measured off of the L1-L3 levels for all patients before and after surgery on pre-op and post-op CT scans.

RESULT

The mean age of patients in this study was 70 (52-84, SD 7). Mean follow-up was 66 (24-132, SD 33) months. Twenty-three patients met criteria for severe deformity (Cobb angle > 50 degrees or SVA > 95 mm or PI/LL mismatch > 20 or PT > 30). Based off 2-year post-op CT scan, there were significant improvements in L1 Hounsfield units when comparing pre-op values (96; SD 55) to post-op values (185 SD 102); p. < 0.05. There was no screw loosening or screw pull out. There were 2 patients with PJF (4.8%). Both these patients had not completed their PTH treatment: one only took PTH for 3 months (PJF at 2-year post-op) and the other one took it only for 1 month (PJF at 1-year post-op). No increase in bone density was noted (based off of Hounsfield units) in five patients (12%) despite completion of their PTH therapy. Only one patient experienced nausea from PTH therapy. There were no other PTH related adverse events.

CONCLUSION

The incidence of PTH analogues failing to increase bone density in our series was low at 12%. This study shows that PTH analogues may be a powerful adjunct for increasing bone density and may help to mitigate the risk of mechanical complications in patients undergoing deformity correction with minimally invasive techniques. Future comparative studies are warranted to confirm these latter findings and to potentially protocolize the ideal peri-operative bone health optimization strategy.

Outcomes of Surgical Treatment for Patients With Mild Scoliosis and Age-Appropriate Sagittal Alignment With Minimum 2-Year Follow-up

OBJECTIVE

The goal of this study was to determine if patients with mild scoliosis and age-appropriate sagittal alignment have favorable outcomes following surgical correction.

METHODS

Retrospective review of a prospective, multicenter adult spinal deformity database. Inclusion criteria: operative patients age ≥18 years, and preoperative pelvic tilt, mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C7 sagittal vertical axis all within established age-adjusted thresholds with minimum 2-year follow-up. Health-related quality of life (HRQoL) scores: Oswestry Disability Index (ODI), 36-item Short Form health survey (SF-36), Scoliosis Research Society-22R (SRS22R), back/leg pain Numerical Rating Scale and minimum clinically important difference (MCID)/substantial clinical benefit (SCB). Two-year and preoperative HRQoL radiographic data were compared. Patients with mild scoliosis (Mild Scoli, Max coronal Cobb 10°-30°) were compared to those with larger curves (Scoli).

RESULTS

One hundred fifty-one patients included from 667 operative patients (82.8% women; average age, 56.4 ± 16.2 years). Forty-two patients (27.8%) included in Mild Scoli group. Mild Scoli group had significantly worse baseline leg pain, ODI, and physical composite scores (p < 0.02). Mean 2-year maximum coronal Cobb angle was significantly improved compared to baseline (p < 0.001). All 2-year HRQoL measures were significantly improved compared to (p < 0.001) except mental composite score, SRS activity and SRS mental for the Mild Scoli group (p > 0.05). From the mild Scoli group, 36%-74% met either MCID or SCB for the HRQoL measures. Sixty-four point three percent had minimum 1 complication, 28.6% had a major complication, 35.7% had reoperation.

CONCLUSION

Mild scoliosis patients with age-appropriate sagittal alignment benefit from surgical correction, decompression, and stabilization at 2 years postoperative despite having a high complication rate.

Correlation Between Sagittal Balance and Mechanical Distal Junctional Failure in Degenerative Pathology of the Spine: A Retrospective Analysis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to investigate the failure of the caudal end of lumbar posterior fixation in terms of pre-operative and post-operative spinopelvic parameters, correction performed, demographic and clinical data.

METHODS

The lumbar, thoraco-lumbar and lumbo-sacral posterior fixations performed with pedicle screws and rods in 2017-2019 were retrospectively analyzed. As 81% failures occurred within 4 years, an observational period of 4 years was chosen. The revision surgeries due to the failure in the caudal end were collected in the junctional group. Fixations which have not failed were gathered in the control group. The main spinopelvic parameters were measured for each patient on standing lateral radiographs with the software Surgimap. Demographic and clinical data were extracted for both groups.

RESULTS

Among the 457 patients who met the inclusion criteria, the junctional group included 101 patients, who required a revision surgery. The control group collected 356 primary fixations. The two most common causes of revision surgeries were screws pullout (57 cases) and rod breakage (53 cases). SVA, PT, LL, PI-LL and TPA differed significantly between the two groups (P = .021 for LL, P < .0001 for all the others). The interaction between the two groups and the pre-operative and post-operative conditions was significant for PT, SS, LL, TK, PI-LL and TPA (P < .005). Sex and BMI did not affect the failure onset.

CONCLUSIONS

Mechanical failure is more likely to occur in patients older than 40 years with a thoraco-lumbar fixation where PT, PI-LL and TPA were not properly restored.

Multidisciplinary conference for complex surgery leads to improved quality and safety

INTRODUCTION

Complex surgery for adult spinal deformity has high rates of complications, reoperations, and readmissions. Preoperative discussions of high-risk operative spine patients at a multidisciplinary conference may contribute to decreased rates of these adverse outcomes through appropriate patient selection and surgical plan optimization. With this goal, we implemented a high-risk case conference involving orthopedic and neurosurgery spine, anesthesia, intraoperative monitoring neurology, and neurological intensive care.

METHODS

Included in this retrospective review were patients ≥ 18 years old meeting one of the following high-risk criteria: 8 + levels fused, osteoporosis with 4 + levels fused, three column osteotomy, anterior revision of the same lumbar level, or planned significant correction for severe myelopathy, scoliosis (> 75˚), or kyphosis (> 75˚). Patients were categorized as Before Conference (BC): surgery before 2/19/2019 or After Conference (AC): surgery after 2/19/2019. Outcome measures include intraoperative and postoperative complications, readmissions, and reoperations.

RESULTS

263 patients were included (96 AC, 167 BC). AC was older than BC (60.0 vs 54.6, p = 0.025) and had lower BMI (27.1 vs 28.9, p = 0.047), but had similar CCI (3.2 vs 2.9 p = 0.312), and ASA Classification (2.5 vs 2.5, p = 0.790). Surgical characteristics, including levels fused (10.6 vs 10.7, p = 0.839), levels decompressed (1.29 vs 1.25, p = 0.863), 3 column osteotomies (10.4% vs 18.6%, p = 0.080), anterior column release (9.4% vs 12.6%, p = 0.432), and revision cases (53.1% vs 52.4%, p = 0.911) were similar between AC and BC. AC had lower EBL (1.1 vs 1.9L, p < 0.001) and fewer total intraoperative complications (16.7% vs 34.1%, p = 0.002), including fewer dural tears (4.2% vs 12.6%, p = 0.025), delayed extubations (8.3% vs 22.8%%, p = 0.003), and massive blood loss (4.2% vs 13.2%, p = 0.018). Length of stay (LOS) was similar between groups (7.2 vs 8.2 days, 0.251). AC had a lower incidence of deep surgical site infections (SSI, 1.0% vs 6.6%, p = 0.038), but a higher rate of hypotension requiring vasopressor therapy (18.8% vs 4.8%, p < 0.001). Other postoperative complications were similar between groups. AC had lower rates of reoperation at 30 (2.1% vs 8.4%, p = 0.040) and 90 days (3.1 vs 12.0%, p = 0.014) and lower readmission rates at 30 (3.1% vs 10.2%, p = 0.038) and 90 days (6.3 vs 15.0%, p = 0.035). On logistic regression, AC patients had higher odds of hypotension requiring vasopressor therapy and lower odds of delayed extubation, intraoperative RBC, and intraoperative salvage blood.

CONCLUSIONS

Following implementation of a multidisciplinary high-risk case conference, 30- and 90-day reoperation and readmission rates, intraoperative complications, and postoperative deep SSIs decreased. Hypotensive events requiring vasopressors increased, but did not result in longer LOS or greater readmissions. These associations suggest a multidisciplinary conference may help improve quality and safety for high-risk spine patients. particularly through minimizing complications and optimizing outcomes in complex spine surgery.

Surgery for Metastatic Spinal Disease in Octogenarians and Above: Analysis of 78 Patients

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

Octogenarians living with spinal metastases are a challenging population to treat. Our objective was to identify the rate, types, management, and predictors of complications and survival in octogenarians following surgery for spinal metastases.

METHODS

A retrospective review of a prospectively collected cohort of patients aged 80 years or older who underwent surgery for metastatic spinal tumor treatment between 2008 and 2019 were included. Demographic, intraoperative, complications, and postoperative follow-up data was collected. Cox proportional hazards regression and logistic regression were used to associate variables with overall survival and postoperative complications, respectively.

RESULTS

78 patients (mean 83.6 years) met inclusion criteria. Average operative time and blood loss were 157 minutes and 615 mL, respectively. The median length of stay was 7 days. The overall complication rate was 31% (N = 24), with 21% considered major and 7% considered life-threatening or fatal. Blood loss was significantly associated with postoperative complications (OR = 1.002; P = 0.02) and mortality (HR = 1.0007; P = 0.04). Significant associations of increased risk of death were also noted with surgeries with decompression, and cervical/cervicothoracic index level of disease. For deceased patients, median time to death was 4.5 months. For living patients, median follow-up was 14.5 months. The Kaplan-Meier based median overall survival for the cohort was 11.6 months (95% CI: 6.2-19.1).

CONCLUSIONS

In octogenarians undergoing surgery with instrumentation for spinal metastases, the median overall survival is 11.6 months. There is an increased complication rate, but only 7% are life-threatening or fatal. Patients are at increased risk for complications and mortality particularly when performing decompression with stabilization, with increasing intraoperative blood loss, and with cervical/cervicothoracic tumors.

Association Between the Bone Density of Posterior Fusion Mass and Mechanical Complications After Thoracolumbar Three-Column Osteotomy for Adult Spinal Deformity

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

To assess the relationship of fusion mass bone density on computed tomography (CT) and the development of rod fractures (RFs) and proximal junctional kyphosis (PJK).

SUMMARY OF BACKGROUND DATA

Few studies have evaluated the relationship of fusion mass bone density to mechanical complications.

MATERIALS AND METHODS

A retrospective review of adult spinal deformity patients who underwent thoracolumbar three-column osteotomy from 2007 to 2017 was performed. All patients underwent routine 1-year CT imaging and had at least 24 months follow-up. Posterior fusion mass bone density was evaluated by measuring hounsfield unit (HU) on CT in three different regions [upper instrumented vertebra (UIV), lower instrumented vertebra, and osteotomy site], and were compared between patients with and without mechanical complications.

RESULTS

A total of 165 patients (63.2 years, 33.5% male) were included. Overall PJK rate was 18.8%, and 35.5% of these underwent PJK revision. There was significantly lower density of posterior fusion mass at the UIV in patients who experienced PJK compared with patients without PJK (431.5HU vs. 537.4HU, P =0.026). Overall RF rate was 34.5% and 61.4% of these underwent revision for RFs. Among 57 patients with RFs, 71.9% had pseudarthrosis. Fusion mass density did not differ between patients with or without RFs. However, in RF patients with pseudarthrosis, there was significantly higher bone mass density near the osteotomy compared with those without pseudarthrosis (515.7HU vs. 354.2HU, P =0.012). There were no differences in radiographic sagittal measures between the patients with and without RF or PJK.

CONCLUSIONS

Patients with PJK tend to have less dense posterior fusion mass at the UIV. Fusion mass density does not correlate with RF, but greater bone density near the osteotomy was correlated with accompanying pseudarthrosis in patients with RFs. Assessing density of posterior fusion mass on CT may be helpful in assessing risk for PJK and provide insight as to the causes of RFs.

Association between sagittal alignment and loads at the adjacent segment in the fused spine: a combined clinical and musculoskeletal modeling study of 205 patients with adult spinal deformity

PURPOSE

Sagittal malalignment is a risk factor for mechanical complications after surgery for adult spinal deformity (ASD). Spinal loads, modulated by sagittal alignment, may explain this relationship. The aims of this study were to investigate the relationships between: (1) postoperative changes in loads at the proximal segment and realignment, and (2) absolute postoperative loads and postoperative alignment measures.

METHODS

A previously validated musculoskeletal model of the whole spine was applied to study a clinical sample of 205 patients with ASD. Based on clinical and radiographic data, pre-and postoperative patient-specific alignments were simulated to predict loads at the proximal segment adjacent to the spinal fusion.

RESULTS

Weak-to-moderate associations were found between pre-to-postop changes in lumbar lordosis, LL (r =  - 0.23, r =  - 0.43; p < 0.001), global tilt, GT (r = 0.26, r = 0.38; p < 0.001) and the Global Alignment and Proportion score, GAP (r = 0.26, r = 0.37; p < 0.001), and changes in compressive and shear forces at the proximal segment. GAP score parameters, thoracic kyphosis measurements and the slope of upper instrumented vertebra were associated with changes in shear. In patients with T10-pelvis fusion, moderate-to-strong associations were found between postoperative sagittal alignment measures and compressive and shear loads, with GT showing the strongest correlations (r = 0.75, r = 0.73, p < 0.001).

CONCLUSIONS

Spinal loads were estimated for patient-specific full spinal alignment profiles in a large cohort of patients with ASD pre-and postoperatively. Loads on the proximal segments were greater in association with sagittal malalignment and malorientation of proximal vertebra. Future work should explore whether they provide a causative mechanism explaining the associated risk of proximal junction complications.

Preoperative characteristics are associated with increased likelihood of low early postoperative mobility after adult spinal deformity surgery

BACKGROUND CONTEXT

Low early postoperative mobility (LEPOM) has been shown to be associated with increased length of hospital stay, complication rates, and likelihood of nonhome discharge. However, few studies have examined preoperative characteristics associated with LEPOM in adult spinal deformity (ASD) patients.

PURPOSE

To investigate which preoperative patient characteristics may be associated with LEPOM after ASD surgery.

DESIGN

Retrospective review.

PATIENT SAMPLE

Included were 86 ASD patients with fusion of ≥5 levels for whom immediate-postoperative AM-PAC Basic Mobility Inpatient Short Form (6-Clicks) scores had been obtained.

OUTCOME MEASURES

The primary outcome of this study was the likelihood of LEPOM, defined as an AM-PAC score ≤15, which is associated with inability to stand for more than 1 minute.

METHODS

Significant cutoffs for preoperative characteristics associated with LEPOM were determined via threshold linear regression. Multivariable logistic regression was used to assess the impact of preoperative characteristics on the likelihood of LEPOM.

RESULTS

LEPOM was recorded in 38 patients (44.2%). Threshold regression identified the following cutoffs to be associated with LEPOM: preoperative Patient Reported Outcomes Measurement Information System (PROMIS) scores of ≥68 for Pain, <28.3 for Physical Function, and ≥63.4 for Anxiety; preoperative Oswestry disability index (ODI) score of ≥60; and body mass index (BMI) of ≥35.2. On multivariate analysis, preoperative PROMIS scores of ≥68 for Pain (odds ratio [OR] 5.3, confidence interval [CI] 1.2-22.8, p=.03), <28.3 for Physical Function (OR 10.1, CI 1.8-58.2, p=.01), and ≥63.4 for Anxiety (OR 4.7, CI 1.1-20.8, p=.04); preoperative ODI score ≥60 (OR 38.8, CI 4.0-373.6, p=.002); BMI ≥35.2 (OR 14.2, CI 1.3-160.0, p=.03), and male sex (OR 5.4, CI 1.2-23.7, p=.03) were associated with increased odds of LEPOM.

CONCLUSIONS

Preoperative PROMIS Pain, Physical Function, and Anxiety scores; ODI score; BMI; and male sex were associated with LEPOM. Several of these characteristics are modifiable risk factors and thus may be candidates for optimization before surgery.

LEVEL OF EVIDENCE

III.

The importance of thoracolumbar junctional orientation, change in thoracolumbar angle, and overcorrection of lumbar lordosis in development of proximal junctional kyphosis in adult spinal deformity surgery

OBJECTIVE

Changes in the thoracolumbar angle (TLA) would play a pivotal role in the reciprocal changes following spine realignment surgery, thereby leading to the development of proximal junctional kyphosis (PJK). This study aimed to investigate the association between TLA and the development of PJK following adult spinal deformity surgery.

METHODS

A total of 107 patients were divided into PJK+ and PJK- groups according to the development of PJK within 12 months after surgery. The TLA and spinopelvic radiological parameters were compared between the PJK+ and PJK- groups. A multivariate logistic regression model was used to identify the risk factors for PJK. The receiver operating characteristic curves of the regression models were used to investigate the cutoff values of significant parameters needed so that PJK would not occur.

RESULTS

The change in TLA (ΔTLA) in the PJK+ group was significantly larger than in the PJK- group (6.7° ± 7.9° and 2.2° ± 8.1°, respectively; p = 0.006). Multivariate logistic regression analysis demonstrated that age, postoperative pelvic incidence-lumbar lordosis, and ΔTLA were significant risk factors for PJK. The risk of developing PJK was higher when the postoperative pelvic incidence-lumbar lordosis was < 5.2 and the ΔTLA was > 3.58°.

CONCLUSIONS

The present study highlights the thinking that extensive correction of TLA and lumbar lordosis should be avoided in patients with adult spinal deformity. Overcorrection of TLA of > 3.58° could result in higher odds of PJK.

Factors influencing complications after 3-columns spinal osteotomies for fixed sagittal imbalance from multiple etiologies: a multicentric cohort study about 286 cases in 273 patients

PURPOSE

Spinal osteotomies performed to treat fixed spinal deformities are technically demanding and associated with a high complications rate. The main purpose of this study was to analyze complications and their risk factors in spinal osteotomies performed for fixed sagittal imbalance from multiple etiologies.

METHODS

The study consisted of a blinded retrospective analysis of prospectively collected data from a large multicenter cohort of patients who underwent 3-columns (3C) spinal osteotomy, between January 2010 and January 2017. Clinical and radiological data were compared pre- and post-operatively. Complications and their risk factors were analyzed.

RESULTS

Two hundred eighty-six 3C osteotomies were performed in 273 patients. At 1 year follow-up, both clinical (VAS pain, ODI and SRS-22 scores) and radiological (SVA, SSA, loss of lordosis and pelvic version) parameters were significantly improved (p < 0.001). A total of 164 patients (59.2%) experienced at least 1 complication (277 complications). Complications-free survival rates were only 30% at 5 years. Most of those were mechanical (35.2%), followed by general (17.6%), surgical site infection (17.2%) and neurological (10.9%). Pre-operative neurological status [RR = 2.3 (1.32-4.00)], operative time (+ 19% of risk each additional hour) and combined surgery [RR = 1.76 (1.08-2.04)] were assessed as risk factors for overall complication (p < 0.05). The use of patient-specific rods appeared to be significantly associated with less overall complications [RR = 0.5 (0.29-0.89)] (p = 0.02).

CONCLUSION

Spinal 3C osteotomies were efficient to improve both clinical and radiological parameters despite high rates of complication. Efforts should be made to reduce operative time which appears to be the strongest predictive risk factor for complication.

Neuromuscular Scoliosis: A Dual-Surgeon Approach

OBJECTIVE

Neuromuscular Scoliosis (NMS) causes severe deformity and operative correction for these patients carries high complication rates. We present a retrospective study comparing a series of consecutive patients who underwent posterior fusion via a single-surgeon (SS) approach with a consecutive series of patients treated via a dual-surgeon (DS) approach.

METHODS

Patients with NMS who underwent posterior fusion via a SS approach from 2019 to 2022 were analyzed and compared to a series of patients with NMS who underwent posterior fusion via a DS approach.

RESULTS

In the SS group, the average estimated blood loss (EBL) was 675 mL, average length of stay (LOS) was 6.3 days, average operative time (OT) was 6.5 hours, average packed red blood cell transfusion was 1.5 units, with a complication rate of 30%. The DS group had an average EBL of 400 mL, a LOS of 4.8 days, an OT of 4.75 hours, an average packed red blood cell transfusion of 0.8 units, with a complication rate of 20%. The DS approach was significant for a lower EBL, OT (P < 0.001), and LOS (P < 0.03).

CONCLUSIONS

This study suggests that for patients with NMS the DS approach decreases OT, EBL, complication rates, and LOS. This further supports that this approach may benefit outcomes in NMS patients.

Outcomes of operative treatment for adult spinal deformity: a prospective multicenter assessment with mean 4-year follow-up

OBJECTIVE

The current literature has primarily focused on the 2-year outcomes of operative adult spinal deformity (ASD) treatment. Longer term durability is important given the invasiveness, complications, and costs of these procedures. The aim of this study was to assess minimum 3-year outcomes and complications of ASD surgery.

METHODS

Operatively treated ASD patients were assessed at baseline, follow-up, and through mailings. Patient-reported outcome measures (PROMs) included scores on the Oswestry Disability Index (ODI), Scoliosis Research Society-22r (SRS-22r) questionnaire, mental component summary (MCS) and physical component summary (PCS) of the SF-36, and numeric rating scale (NRS) for back and leg pain. Complications were classified as perioperative (≤ 90 days), delayed (90 days to 2 years), and long term (≥ 2 years). Analyses focused on patients with minimum 3-year follow-up.

RESULTS

Of 569 patients, 427 (75%) with minimum 3-year follow-up (mean ± SD [range] 4.1 ± 1.1 [3.0-9.6] years) had a mean age of 60.8 years and 75% were women. Operative treatment included a posterior approach for 426 patients (99%), with a mean ± SD 12 ± 4 fusion levels. Anterior lumbar interbody fusion was performed in 35 (8%) patients, and 89 (21%) underwent 3-column osteotomy. All PROMs improved significantly from baseline to last follow-up, including scores on ODI (45.4 to 30.5), PCS (31.0 to 38.5), MCS (45.3 to 50.6), SRS-22r total (2.7 to 3.6), SRS-22r activity (2.8 to 3.5), SRS-22r pain (2.3 to 3.4), SRS-22r appearance (2.4 to 3.5), SRS-22r mental (3.4 to 3.7), SRS-22r satisfaction (2.7 to 4.1), NRS for back pain (7.1 to 3.8), and NRS for leg pain (4.8 to 3.0) (all p < 0.001). Degradations in some outcome measures were observed between the 2-year and last follow-up evaluations, but the magnitudes of these degradations were modest and arguably not clinically significant. Overall, 277 (65%) patients had at least 1 complication, including 185 (43%) perioperative, 118 (27%) delayed, and 56 (13%) long term. Notably, the 142 patients who did not achieve 3-year follow-up were similar to the study patients in terms of demographic characteristics, deformities, and baseline PROMs and had similar rates and types of complications.

CONCLUSIONS

This prospective multicenter analysis demonstrated that operative ASD treatment provided significant improvement of health-related quality of life at minimum 3-year follow-up (mean 4.1 years), suggesting that the benefits of surgery for ASD remain durable at longer follow-up. These findings should prove useful for counseling, cost-effectiveness assessments, and efforts to improve the safety of care.

Cost-utility Analysis of Neoadjuvant Teriparatide Therapy in Osteopenic Patients Undergoing Adult Spinal Deformity Surgery

STUDY DESIGN

A cost-utility analysis study.

OBJECTIVE

This study aims to evaluate the cost-utility of neoadjuvant teriparatide therapy in osteopenic patients undergoing adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

There is increasing evidence supporting preoperative use of anabolic agents such as teriparatide for preoperative optimization of ASD patients with poor bone density. However, such treatments are associated with added costs. To our knowledge, the cost-utility of teriparatide in osteopenic patients undergoing ASD surgery has not been established.

MATERIALS AND METHODS

A decision-analysis model was developed for a hypothetical 68-year-old female patient with osteopenia ( T score <-1.0) undergoing a T11 to pelvis instrumented spinal fusion for ASD. A comprehensive literature review was conducted to create estimates for event probabilities, costs, and quality adjusted life years at each node. Key model assumptions were that administration of a 4-month preoperative teriparatide course reduced 2-year postoperative reoperation rates [for pseudarthrosis from 5% to 2.5% and for proximal junctional failure (PJF) from 15% to 5%]. Monte Carlo simulations were used to calculate the mean incremental cost utility ratio and incremental net monetary benefits. One-way sensitivity analysis was used to estimate the contribution of individual parameters to uncertainty in the model.

RESULTS

Teriparatide was the favored strategy in 82% of the iterations. The mean incremental cost utility ratio for the teriparatide strategy was negative (higher net benefit, lower net cost), and lower than the willingness-to-pay threshold of $50,000 per quality adjusted life year. Teriparatide use was associated with a mean incremental net monetary benefit of $3,948. One-way sensitivity analysis demonstrated that the factors with the greatest impact on the model were the incidence of PJF in the no teriparatide group, the duration and monthly cost of treatment, and the cost of reoperation due to PJF.

CONCLUSIONS

Neoadjuvant teriparatide is a cost-effective strategy to reduce postoperative complications in patients with osteopenia undergoing ASD surgery.

Apical region correction and global balance: a 3-rods surgical strategy for the treatment of severe and rigid scoliosis

Background

The treatment of severe and rigid scoliosis is challenging. We developed a surgical strategy for severe and rigid scoliosis since 2014. This study aimed to retrospectively analyze the safety and efficacy of apical region correction and global balance with 3 rods as a surgical strategy for the treatment of severe and rigid scoliosis.

Methods

A retrospective study was performed for patients with severe and rigid scoliosis who underwent one-stage posterior corrective operation using the apical region correction and global balance with 3 rods surgical strategy between February 2014 and April 2020. The inclusion criteria were as follows: [1] Cobb angle > 90°; [2] flexibility < 30%; [3] a minimum 2-year follow-up. Patients were excluded if they had a history of traction or spinal surgery. Coronal and sagittal parameters, including Cobb angle, flexibility, apex vertebra translation, trunk shift (TS), thoracic kyphosis, lumbar lordosis, and sagittal vertical axis (SVA) were measured preoperatively, postoperatively and at the final follow-up. The Scoliosis Research Society 22-item questionnaire was administered preoperatively and at the final follow-up. During the operation, one slightly-bent short rod was placed into the concave side of apical region and correction was achieved by rod-rotation and distraction. Two pre-bent long rods were placed into both sides of the scoliosis and global balance was improved by leveling the proximal thoracic vertebrae and distal lumbar vertebrae.

Results

A total of 41 patients were included, with an average age of 20 years (range, 12–49 years) and follow-up of 34 months (range, 24–58 months). Postoperative correction rate was 53% for scoliosis. There were 14 patients with normal kyphosis before surgery, and 28 patients with normal kyphosis at the last follow-up. 88% of the patients (23/26) with preoperative coronal imbalance (TS > 20 mm) restored coronal balance at the final follow-up. 87% of the patients (14/16) with preoperative sagittal imbalance (SVA > 40 mm) restored sagittal balance at the final follow-up. The mean operation time and blood loss were 286 min and 941 mL, respectively. No patients had neurological complications or implant failure.

Conclusion

The surgical strategy of apical region correction and global balance with 3 rods is a safe and effective alternative for the surgical treatment of severe and rigid scoliosis.

An Artificial Neural Network Model for the Prediction of Perioperative Blood Transfusion in Adult Spinal Deformity Surgery

Prediction of blood transfusion after adult spinal deformity (ASD) surgery can identify at-risk patients and potentially reduce its utilization and the complications associated with it. The use of artificial neural networks (ANNs) offers the potential for high predictive capability. A total of 1173 patients who underwent surgery for ASD were identified in the 2017–2019 NSQIP databases. The data were split into 70% training and 30% testing cohorts. Eighteen patient and operative variables were used. The outcome variable was receiving RBC transfusion intraoperatively or within 72 h after surgery. The model was assessed by its sensitivity, positive predictive value, F1-score, accuracy (ACC), and area under the curve (AUROC). Average patient age was 56 years and 63% were female. Pelvic fixation was performed in 21.3% of patients and three-column osteotomies in 19.5% of cases. The transfusion rate was 50.0% (586/1173 patients). The best model showed an overall ACC of 81% and 77% on the training and testing data, respectively. On the testing data, the sensitivity was 80%, the positive predictive value 76%, and the F1-score was 78%. The AUROC was 0.84. ANNs may allow the identification of at-risk patients, potentially decrease the risk of transfusion via strategic planning, and improve resource allocation.

Combined anterior-posterior versus all-posterior approaches for adult spinal deformity correction: a matched control study

PURPOSE

Anterior approaches are gaining popularity for adult spinal deformity (ASD) surgeries especially with the introduction of hyperlordotic cages and improvement in MIS techniques. Combined Approaches provide powerful segmental sagittal correction potential and increase the surface area available for fusion in ASD surgery, both of which would improve overall. This is the first study directly comparing surgical outcomes between combined anterior-posterior approaches and all-posterior approach in a matched ASD population.

METHODS

This is a retrospective matched control cohort analysis with substitution using a multicenter prospectively collected ASD data of patients with > 2 year FU. Matching criteria include: age, American Society of Anesthesiologists Score, Lumbar Cobb angle, sagittal deformity (Global tilt) and ODI.

RESULTS

In total, 1024 ASD patients were available for analysis. 29 Combined Approaches patients met inclusion criteria, and only 22 could be matched (1:2 ratio). Preoperative non-matched demographical, clinical, surgical and radiological parameters were comparable between both groups. Combined approaches had longer surgeries (548 mns vs 283) with more blood loss (2850 ml vs 1471) and needed longer ICU stays (74 h vs 27). Despite added morbidity, they had comparable complication rates but with significantly less readmissions (9.1% vs 38.1%) and reoperations (18.2% vs 43.2%) at 2 years. Combined Approaches achieved more individualised and harmonious deformity correction initially. At the 2 years control, Combined Approaches patients reported better outcomes as measured by COMI and SRS scores. This trend was maintained at 3 years.

CONCLUSION

Despite an increased initial surgical invasiveness, combined approaches seem to achieve more harmonious correction with superior sagittal deformity control; they need fewer revisions and have improved long-term functional outcomes when compared to all-posterior approaches for ASD deformity correction.

Post-operative L5 radiculopathy after L5-S1 hyperlordotic anterior lumbar interbody fusion (HL-ALIF) is related to a greater increase of lordosis and smaller post-operative posterior disc height: results from a cohort study

STUDY DESIGN

A single-centre retrospective study.

BACKGROUND AND PURPOSE

This study aims to investigate the rate of L5 radiculopathy, to identify imaging features associated with the complication and to evaluate the clinical outcomes in adult spine deformity patients undergoing L5-S1 ALIF with hyperlordotic cages.

METHODS

Design: retrospective cohort study. A single-centre prospective database was queried to analyse patients undergoing hyperlordotic (HL) ALIF with posterior fusion to correct spinal deformity. Clinical status was evaluated by back and leg pain numeric rate scale and Oswestry Disability Index pre-operatively and at 3-, 6- and 12-month follow-up. Spinopelvic parameters, such as pelvic incidence, pelvic tilt, lumbar lordosis and L5-S1 lordosis, posterior disc height (PDH) and anterior disc height, were assessed pre-operatively and post-operatively on standardized full-spine standing EOS images. The sagittal foraminal area was measured pre- and post-operatively on a CT scan.

RESULTS

Thirty-nine patients with a mean age of 63.2 ± 8.6 years underwent HL-ALIF from January 2016 to December 2019. Seven of them developed post-operative root pain (5) or weakness (2) (Group A), while thirty-two did not (Group B). Root impairment was associated with greater segmental correction magnitude, 26° ± 11.1 in Group A versus 15.1° ± 9.9 in Group B (p < 0.05), and to smaller post-operative PDH, 5.9 mm ± 2.7 in Group A versus 8.3 mm ± 2.6 (p < 0.05).

CONCLUSIONS

Post-operative root problems were observed in 17.9% of patients undergoing HL-ALIF for adult spine deformity. L5 radiculopathy was associated with larger sagittal angular corrections and smaller post-operative posterior disc height. One patient (2.6%) needed L5 root decompression. At 12 months of follow-up, results were equivalent between groups.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Surgeons' risk perception in ASD surgery: The value of objective risk assessment on decision making and patient counselling

BACKGROUND

Surgeons often rely on their intuition, experience and published data for surgical decision making and informed consent. Literature provides average values that do not allow for individualized assessments. Accurate validated machine learning (ML) risk calculators for adult spinal deformity (ASD) patients, based on 10 year multicentric prospective data, are currently available. The objective of this study is to assess surgeon ASD risk perception and compare it to validated risk calculator estimates.

METHODS

Nine ASD complete (demographics, HRQL, radiology, surgical plan) preoperative cases were distributed online to 100 surgeons from 22 countries. Surgeons were asked to determine the risk of major complications and reoperations at 72 h, 90 d and 2 years postop, using a 0-100% risk scale. The same preoperative parameters circulated to surgeons were used to obtain ML risk calculator estimates. Concordance between surgeons' responses was analyzed using intraclass correlation coefficients (ICC) (poor < 0.5/excellent > 0.85). Distance between surgeons' and risk calculator predictions was assessed using the mean index of agreement (MIA) (poor < 0.5/excellent > 0.85).

RESULTS

Thirty-nine surgeons (74.4% with > 10 years' experience), from 12 countries answered the survey. Surgeons' risk perception concordance was very low and heterogeneous. ICC ranged from 0.104 (reintervention risk at 72 h) to 0.316 (reintervention risk at 2 years). Distance between calculator and surgeon prediction was very large. MIA ranged from 0.122 to 0.416. Surgeons tended to overestimate the risk of major complications and reintervention in the first 72 h and underestimated the same risks at 2 years postop.

CONCLUSIONS

This study shows that expert surgeon ASD risk perception is heterogeneous and highly discordant. Available validated ML ASD risk calculators can enable surgeons to provide more accurate and objective prognosis to adjust patient expectations, in real time, at the point of care.

Use of demineralized cortical fibers is associated with reduced risk of pseudarthrosis after pedicle subtraction osteotomy for adult spinal deformity

PURPOSE

To assess the effect of demineralized cortical fibers (DCF) on postoperative pseudarthrosis requiring revision surgery in patients undergoing pedicle subtraction osteotomy (PSO) for adult spinal deformity (ASD).

METHODS

The use of DCF was introduced across all procedures in 2017 and subsequent patients undergoing PSO surgery were prospectively and consecutively registered. Following sample-size estimation, a retrospective cohort was also registered undergoing the same procedure immediately prior to the implementation of DCF. The non-DCF group underwent surgery with ABG. Minimum follow-up was 2 years in both groups. The main outcome was postoperative pseudarthrosis, either CT-verified or verified intraoperatively during revision surgery due to rod breakage and assessed using Kaplan-Meier survival analyses.

RESULTS

A total of 48 patients were included in the DCF group and 76 in the non-DCF group. The DCF group had more frequently undergone previous spine surgery (60% vs 36%) and had shorter follow-up (32 ± 2 vs 40 ± 7 months). Pseudarthrosis occurred in 7 (15%) patients in the DCF group and 31 (41%) in the non-DCF group, corresponding to a relative risk increase of 2.6 (95%CI 1.3-2.4, P < 0.01). 1-KM survival analyses, taking time to event into account and thus the difference in follow-up, also showed increased pseudarthrosis in the non-DCF group (log-rank P = 0.022). Similarly, multivariate logistic regression adjusted for age, instrumented levels and sacral fusion was also with significantly increased odds of pseudarthrosis in the non-DCF group (OR: 4.3, 95%CI: 1.7-11.3, P < 0.01).

CONCLUSION

We found considerable and significant reductions in pseudarthrosis following PSO surgery with DCF compared to non-DCF.

LEVEL OF EVIDENCE

III.

Trends in Intraoperative Assessment of Spinal Alignment: A Survey of Spine Surgeons in the United States

STUDY DESIGN

Survey.

OBJECTIVES

To characterize national practices of and shortcomings surrounding intraoperative assessments of spinal alignment.

METHODS

Spine surgeons in the US were surveyed to analyze their experience with assessing spinal alignment intraoperatively.

RESULTS

108 US spine surgeons from 77 surgical centers with an average of 19.2 + 8.8 years of surgical experience completed the survey. To assess alignment intraoperatively, 84% (91/108) use C-arm or spot radiographs, 40% (43/108) use full-length radiographs, and 20% utilize the T-bar (22/108). 88% of respondents' surgical centers (93/106) possessed a navigation camera and 63% of respondents (68/108) report using surgical navigation for 40% of their deformity cases on average. Reported deterrents for using current technology to assess alignment were workflow interruption (54%, 58/108), expense (33%, 36/108), and added radiation exposure (26%, 28/108). 87% of respondents (82/94) reported a need for improvement in current capabilities of making intraoperative assessments of spinal alignment.

CONCLUSIONS

Corrective surgery for spinal deformity is a complex procedure that requires a high level of expertise to perform safely. The majority of surveyed surgeons primarily rely on radiographs for intraoperative assessments of alignment. Despite the majority of surveyed surgical practices possessing navigation cameras, they are utilized only for a minority of spinal deformity cases. With the majority of surveyed surgeons reporting a need for improvement in technology to assess spinal alignment intraoperatively, 3 of the top design considerations should include workflow interruption, expense, and radiation exposure.

Quality metrics in adult spinal deformity surgery over the last decade: a combined analysis of the largest prospective multicenter data sets

OBJECTIVE

The reported rate of complications and cost of adult spinal deformity (ASD) surgery, associated with an exponential increase in the number of surgeries, cause alarm among healthcare payers and providers worldwide. The authors conjointly analyzed the largest prospective available ASD data sets to define trends in quality-of-care indicators (complications, reinterventions, and health-related quality of life [HRQOL] outcomes) since 2010.

METHODS

This is an observational prospective longitudinal cohort study. Patients underwent surgery between January 2010 and December 2016, with > 2 years of follow-up data. Demographic, surgical, radiological, and HRQOL (i.e., Oswestry Disability Index, SF-36, Scoliosis Research Society-22r) data obtained preoperatively and at 3, 6, 12, and 24 months after surgery were evaluated. Trends and changes in indicators were analyzed using local regression (i.e., locally estimated scatterplot smoothing [LOESS]) and adjusted odds ratio (OR).

RESULTS

Of the 2286 patients included in the 2 registries, 1520 underwent surgery between 2010 and 2016. A total of 1151 (75.7%) patients who were treated surgically at 23 centers in 5 countries met inclusion criteria. Patient recruitment increased progressively (2010-2011 vs 2015-2016: OR 1.64, p < 0.01), whereas baseline clinical characteristics (age, American Society of Anesthesiologists class, HRQOL scores, sagittal deformity) did not change. Since 2010 there has been a sustained reduction in major and minor postoperative complications observed at 90 days (major: OR 0.59; minor: OR 0.65; p < 0.01); at 1 year (major: OR 0.52; minor: 0.75; p < 0.01); and at 2 years of follow-up (major: OR 0.4; minor: 0.80; p < 0.01) as well as in the 2-year reintervention rate (OR 0.41, p < 0.01). Simultaneously, there has been a slight improvement in the correction of sagittal deformity (i.e., pelvic incidence-lumbar lordosis mismatch: OR 1.11, p = 0.19) and a greater gain in quality of life (i.e., Oswestry Disability Index 26% vs 40%, p = 0.02; Scoliosis Research Society-22r, self-image domain OR 1.16, p = 0.13), and these are associated with a progressive reduction of surgical aggressiveness (number of fused segments: OR 0.81, p < 0.01; percent pelvic fixation: OR 0.66, p < 0.01; percent 3-column osteotomies: OR 0.63, p < 0.01).

CONCLUSIONS

The best available data show a robust global improvement in quality metrics in ASD surgery over the last decade. Surgical complications and reoperations have been reduced by half, while improvement in disability increased and correction rates were maintained, in patients with similar baseline characteristics.

Surgical Factors and Treatment Severity for Perioperative Complications Predict Hospital Length of Stay in Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective review of prospectively collected multicenter registry data.

OBJECTIVE

The aim of this study was to determine whether surgical variables and complications as graded by treatment severity impact postoperative hospital length of stay (LOS).

SUMMARY OF BACKGROUND DATA

Surgical treatment can substantially improve quality of life for patients with adult spinal deformity (ASD). However, surgical treatment is associated with high complication rates, which may impact hospital LOS. Classifying complications by severity of subsequent treatment may allow surgeons to better understand complications and predict their impact on important outcome metrics, including LOS.

METHODS

Patients enrolled in a multicenter, prospectively enrolled database for ASD were assessed for study inclusion. Complications were graded based on intervention severity. Associations between LOS, complication intervention severity, and surgical variables (fusion length, use of interbody fusion, use of major osteotomy, primary versus revision surgery, same day vs. staged surgery, and surgical approach), were assessed. Two multivariate regression models were constructed to assess for independent associations with LOS.

RESULTS

Of 1183 patients meeting inclusion criteria, 708 did not and 475 did experience a perioperative complication during their index hospitalization, with 660 and 436 included in the final cohorts, respectively. Among those with complications, intervention severities included 14.9% with no intervention, 68.6% with minor, 8.9% with moderate, and 7.6% with severe interventions. Multivariate regression modeling demonstrated that length of posterior fusion, use of major osteotomy, staged surgery, and severity of intervention for complications were significantly associated with LOS.

CONCLUSION

Careful selection of surgical factors may help reduce hospital LOS following surgery for ASD. Classification of complications by treatment severity can help surgeons better understand and predict the implications of complications, in turn assisting with surgical planning and patient counseling.Level of Evidence: 4.

A predictive model of perioperative myocardial infarction following elective spine surgery

Myocardial infarction (MI), and its predictive factors, has been an understudied complication following spine operations. The objective was to assess the risk factors for perioperative MI in elective spine surgery patients as a retrospective case control study. Elective spine surgery patients with a perioperative MI were isolated in the NSQIP. The relationship between MI and non-MI spine patients was assessed using chi-squared and independent samples t-tests. Univariate/multivariate analyses assessed predictive factors of MI. Logistic regression with stepwise model selection was employed to create a model to predict MI occurrence. The study included 196,523 elective spine surgery patients (57.1 yrs, 48%F, 30.4 kg/m²), and 436 patients with acute MI (Spine-MI). Incidence of MI did not change from 2010 to 2016 (0.2%-0.3%, p = 0.298). Spine-MI patients underwent more fusions than patients without MI (73.6% vs 58.4%, p < 0.001), with an average of 1.03 levels fused. Spine-MI patients also had significantly more SPO (5.0% vs 1.8%, p < 0.001) and 3CO (0.9% vs 0.2%, p < 0.001), but less decompression-only procedures (26.4% vs 41.6%, p < 0.001). Spine-MI underwent more revisions (5.3% vs 2.9%, p = 0.003), had greater invasiveness scores (3.41 vs 2.73, p < 0.001) and longer operative times (211.6 vs 147.3 min, p < 0.001). Mortality rate for Spine-MI patients was 4.6% versus 0.05% (p < 0.001). Multivariate modeling for Spine-MI predictors yielded an AUC of 83.7%, and included history of diabetes, cardiac arrest and PVD, past blood transfusion, dialysis-dependence, low preoperative platelet count, superficial SSI and days from operation to discharge. A model with good predictive capacity for MI after spine surgery now exists and can aid in risk-stratification of patients, consequently improving preoperative patient counseling and optimization in the peri-operative period.

Ligament Augmentation With Mersilene Tape Reduces the Rates of Proximal Junctional Kyphosis and Failure in Adult Spinal Deformity

OBJECTIVE

To investigate prevention of proximal junctional kyphosis (PJK) and failure (PJF) following adult spinal deformity (ASD) surgery utilizing a novel technique of posterior ligament augmentation with polyester fiber tether.

METHODS

This study evaluated ASD adult patients who underwent posterior decompression and instrumented fusion from the thoracolumbar junction (T9-L1) to the pelvis from 2011-2017. Basic demographic data were obtained. Radiographic outcomes included proximal junctional angle (PJA), sagittal vertical axis, PJK, and PJF. The study population was divided into patients who had ASD surgery with and without ligamentous augmentation.

RESULTS

A total of 43 subjects were evaluated, including 20 without and 23 with ligamentous augmentation. PJA increased over time for both groups. PJA was smaller for the augmented group, and rate of increase in PJA was slower in the augmented group (p < 0.0001). The rate of PJK was significantly higher in the nonaugmented group (p = 0.01). PJF was significantly less common in the augmented group (p = 0.003). Time to revision surgery was lower in the nonaugmented group (p = 0.003).

CONCLUSION

Our novel ligament augmentation technique utilizing polyethylene tape is an effective technique to slow progression of the PJA and lower the risk for proximal junctional disease in ASD surgery.

Coronal Correction Using Kickstand Rods for Adult Thoracolumbar/Lumbar Scoliosis: Case Series With Analysis of Early Outcomes and Complications

BACKGROUND

The "kickstand rod technique" has been recently described for achieving and maintaining coronal correction in adult spinal deformity (ASD). Kickstand rods span scoliotic lumbar spine from the thoracolumbar junction proximally to a "kickstand iliac screw" distally. Using the iliac wing as a base, kickstand distraction produces powerful corrective forces. Limited literature exists for this technique, and its associated outcomes and complications are unknown.

OBJECTIVE

To assess alignment changes, early outcomes, and complications associated with kickstand rod distraction for ASD.

METHODS

Consecutive ASD patients treated with kickstand distraction at our institution were retrospectively analyzed.

RESULTS

The cohort comprised 19 patients (mean age: 67 yr; 79% women; 63% prior fusion) with mean follow-up 21 wk (range: 2-72 wk). All patients had posterior-only approach surgery with tri-iliac fixation (third iliac screw for the kickstand) for mean fusion length 12 levels. Three-column osteotomy and lumbar transforaminal lumbar interbody fusion were performed in 5 (26%) and 15 (79%) patients, respectively. Postoperative alignment improved significantly (coronal balance: 8 to 1 cm [P < .001]; major curve: 37° to 12° [P < .001]; fractional curve: 20° to 10° [P < .001]; sagittal balance: 11 to 4 cm [P < .001]; pelvic incidence to lumbar lordosis mismatch: 38° to 9° [P < .001]). Pain Numerical Rating Scale scores improved significantly (back: 7.2 to 4.2 [P = .001]; leg: 5.9 to 1.7 [P = .001]). No instrumentation complications occurred. Motor weakness persisted in 1 patient. There were 3 reoperations (1-PJK, 1-wound dehiscence, and 1-overcorrection).

CONCLUSION

Among 19 ASD patients treated with kickstand rod distraction, alignment, and back/leg pain improved significantly following surgery. Complication rates were reasonable.

Single- versus Dual-Attending Surgeon Approach for Spine Deformity: A Systematic Review and Meta-Analysis

BACKGROUND

Surgical management of spine deformity is associated with significant morbidity. Recent literature has inconsistently demonstrated better outcomes after utilizing 2 attending surgeons for spine deformity.

OBJECTIVE

To conduct a systematic review and meta-analysis on studies reporting outcomes following single- vs dual-attending surgeons for spine deformity.

METHODS

MEDLINE, Embase, Web of science, and Cochrane databases were last searched on July 16, 2020. A total of 1013 records were identified excluding duplicates. After screening, 10 studies (4 cohort, 6 case series) were included in the meta-analysis. Random-effect models were used to pool the effect estimates by study design. When feasible, further subgroup analysis by deformity type was conducted.

RESULTS

A total of 953 patients were analyzed. Pooled results from propensity score-matched cohort studies revealed that the single-surgeon approach was unfavorably associated with a nonstatistically significant higher blood loss (mean difference = 421.0 mL; 95% CI: -28.2, 870.2), a statistically significant higher operative time (mean difference = 94.3 min; 95% CI: 54.9, 133), length of stay (mean difference = 0.84 d; 95% CI: 0.46, 1.22), and an increased risk of complications (Mantel-Haenszel risk ratio = 2.93; 95% CI: 1.12, 7.66). Data from pooled case series demonstrated similar results for all outcomes. Moreover, these results did not differ significantly between deformity types (adolescent idiopathic scoliosis and adult spinal deformity).

CONCLUSION

Dual-attending surgeon approach appeared to be associated with reduced operative time, shorter hospital stays, and reduced risk of complications. These findings may potentially improve outcomes in surgical treatment of spine deformity.

Outcomes of Surgical Treatment for One Hundred Thirty-Eight Patients With Severe Sagittal Deformity at a Minimum 2-Year Follow-up: A Case Series

BACKGROUND

Operative treatment of adult spinal deformity (ASD) can be very challenging with high complication rates. It is well established that patients benefit from such treatment; however, the surgical outcomes for patients with severe sagittal deformity have not been reported.

OBJECTIVE

To report the outcomes of patients undergoing surgical correction for severe sagittal deformity.

METHODS

Retrospective review of a prospective, multicenter ASD database. Inclusion criteria: operative patients age ≥18, sagittal vertical axis (SVA) ≥15 cm, mismatch between pelvic incidence and lumbar lordosis (PI-LL) ≥30°, and/or lumbar kyphosis ≥5° with minimum 2 yr follow-up. Health-related quality of life (HRQOL) scores including minimal clinically important difference (MCID)/substantial clinical benefit (SCB), sagittal and coronal radiographic values, demographic, frailty, surgical, and complication data were collected. Comparisons between 2 yr postoperative and baseline HRQOL/radiographic data were made. P < .05 was significant.

RESULTS

A total of 138 patients were included from 502 operative patients (54.3% Female, Average (Avg) age 63.3 ± 11.5 yr). Avg operating room (OR) time 386.2 ± 136.5 min, estimated blood loss (EBL) 1829.8 ± 1474.6 cc. A total of 71(51.4%) had prior fusion. A total of 89.9% were posterior fusion only. Mean posterior levels fused 11.5 ± 4.1. A total of 44.9% had a 3-column osteotomy. All 2 yr postoperative radiographic parameters were significantly improved compared to baseline (P < .001 for all). All 2yr HRQOL measures were significantly improved compared to baseline (P < .004 for all). A total of 46.6% to 73.8% of patients met either MCID/SCB for all HRQOL. A total of 74.6% of patients had at least 1 complication, 11.6% had 4 or more complications, 33.3% had minimum 1 major complication, and 42(30.4%) had a postop revision.

CONCLUSION

Patients with severe sagittal malalignment benefit from surgical correction at 2 yr postoperative both radiographically and clinically despite having a high complication rate.

Factors and predictive model associated with perioperative complications after long fusion in the treatment of adult non-degenerative scoliosis

Introduction

Adult non-degenerative scoliosis accounts for 90% of spinal deformities in young adults. However, perioperative complications and related risk factors of long posterior instrumentation and fusion for the treatment of adult non-degenerative scoliosis have not been adequately studied.

Methods

We evaluated clinical and radiographical results from 146 patients with adult non-degenerative scoliosis who underwent long posterior instrumentation and fusion. Preoperative clinical data, intraoperative variables, and perioperative radiographic parameters were collected to analyze the risk factors for perioperative complications. Potential and independent risk factors for perioperative complications were evaluated by univariate analysis and logistic regression analysis.

Results

One hundred forty-six adult non-degenerative scoliosis patients were included in our study. There were 23 perioperative complications for 21 (14.4%) patients, eight of which were cardiopulmonary complications, two of which were infection, six of which were neurological complications, three of which were gastrointestinal complications, and four of which were incision-related complication. The independent risk factors for development of total perioperative complications included change in Cobb angle (odds ratio [OR] = 1.085, 95% CI = 1.035 ~ 1.137, P = 0.001) and spinal osteotomy (OR = 3.565, 95% CI = 1.039 ~ 12.236, P = 0.043). The independent risk factor for minor perioperative complications is change in Cobb angle (OR = 1.092, 95% CI = 1.023 ~ 1.165, P = 0.008). The independent risk factors for major perioperative complications are spinal osteotomy (OR = 4.475, 95% CI = 1.960 ~ 20.861, P = 0.036) and change in Cobb angle (OR = 1.106, 95% CI = 1.035 ~ 1.182, P = 0.003).

Conclusions

Our study indicate that change in Cobb angle and spinal osteotomy are independent risk factors for total perioperative complications after long-segment posterior instrumentation and fusion in adult non-degenerative scoliosis patients. Change in Cobb angle is an independent risk factor for minor perioperative complications. Change in Cobb angle and spinal osteotomy are independent risk factors for major perioperative complications.

Reducing revision rates following Pedicle Subtraction Osteotomy surgery: a single-center experience of trends over 7 years in patients with Adult Spinal Deformity

STUDY DESIGN

This is a single-center, retrospective study.

OBJECTIVE

To assess if implemented changes to clinical practice have reduced mechanical complications following pedicle subtraction osteotomy (PSO) surgery. Adult spinal deformity (ASD) is increasing in prevalence with concurrent increasing demands for surgical treatment. The most extensive technique, PSO, allows for major correction of rigid deformities. However, surgery-related complications have been reported in rates up to 77% and especially mechanical complications occur at unsatisfactory frequencies.

METHODS

We retrospectively included all patients undergoing PSO for ASD between 2010 and 2016. Changes to clinical practice were introduced continuously in the study period, including rigorous patient selection; inter-disciplinary conferences; implant-material; number of surgeons; surgeon experience; and perioperative standardized protocols for pain, neuromonitoring and blood-loss management. Postoperative complications were recorded in the 2-year follow-up period. Competing risk survival analysis was used to assess cumulative incidence of revision surgery due to mechanical complications. The Mann-Kendall test was used for analysis of trends.

RESULTS

We included 185 patients undergoing PSO. The level of PSO changed over the study period (P < 0.01) with L3 being the most common level in 2010 compared to L4 in 2016. Both preoperative and surgical corrections of sagittal vertical axis were larger towards the end of the study period. The 2-year revision rate due to mechanical failure steadily declined over the study period from 52% in 2010 to 14% for patients treated in 2016, although without statistically significant trend (P = 0.072). In addition, rates of mechanical complications steadily declined over the study period and significant decreasing trends were observed in time trend analyses of overall complications, major complications and rod breakage.

CONCLUSIONS

We observed decreased risks of revision surgery due to mechanical complications following PSO in patients with ASD over a 7-year period. We attribute these improvements to advancements in patient selection, surgical planning and techniques, surgeon experience and more standardized perioperative care.

LEVEL OF EVIDENCE

III.

Biomechanical comparison of semirigid junctional fixation techniques to prevent proximal junctional failure after thoracolumbar adult spinal deformity correction

BACKGROUND CONTEXT

Adult spinal deformity patients treated operatively by long-segment instrumented spinal fusion are prone to develop proximal junctional kyphosis (PJK) and failure (PJF). A gradual transition in range of motion (ROM) at the proximal end of spinal instrumentation may reduce the incidence of PJK and PJF, however, previously evaluated techniques have not directly been compared.

PURPOSE

To determine the biomechanical characteristics of five different posterior spinal instrumentation techniques to achieve semirigid junctional fixation, or "topping-off," between the rigid pedicle screw fixation (PSF) and the proximal uninstrumented spine.

STUDY DESIGN

Biomechanical cadaveric study.

METHODS

Seven fresh-frozen human cadaveric spine segments (T8-L3) were subjected to ex vivo pure moment loading in flexion-extension, lateral bending and axial rotation up to 5 Nm. The native condition, three-level PSF (T11-L2), PSF with supplemental transverse process hooks at T10 (TPH), and two sublaminar taping techniques (knotted and clamped) as one- (T10) or two-level (T9, T10) semirigid junctional fixation techniques were compared. The ROM and neutral zone (NZ) of the segments were normalized to the native condition. The linearity of the transition zones over three or four segments was determined through linear regression analysis.

RESULTS

All techniques achieved a significantly reduced ROM at T10-T11 in flexion-extension and axial rotation relative to the PSF condition. Additionally, both two-level sublaminar taping techniques (CT2, KT2) had a significantly reduced ROM at T9-T10. One-level clamped sublaminar tape (CT1) had a significantly lower ROM and NZ compared with one-level knotted sublaminar tape (KT1) at T10-T11. Linear regression analysis showed the highest linear correlation between ROM and vertebral level for TPH and the lowest linear correlation for CT2.

CONCLUSIONS

All studied semirigid junctional fixation techniques significantly reduced the ROM at the junctional levels and thus provide a more gradual transition than pedicle screws. TPH achieves the most linear transition over three vertebrae, whereas KT2 achieves that over four vertebrae. In contrast, CT2 effectively is a one-level semirigid junctional fixation technique with a shift in the upper rigid fixation level. Clamped sublaminar tape reduces the NZ greatly, whereas knotted sublaminar tape and TPH maintain a more physiologic NZ. Clinical validation is ultimately required to translate the biomechanics of various semirigid junctional fixation techniques into the clinical goal of reducing the incidence of proximal junctional kyphosis and failure.

CLINICAL SIGNIFICANCE

The direct biomechanical comparison of multiple instrumentation techniques that aim to reduce the incidence of PJK after thoracolumbar spinal fusion surgery provides a basis upon which clinical studies could be designed. Furthermore, the data provided in this study can be used to further analyze the biomechanical effects of the studied techniques using finite element models to better predict their post-operative effectiveness.

Proximal junctional fracture and kyphosis after long spinopelvic corrective fixation for adult spinal deformity

BACKGROUND

Proximal junctional fractures (PJFx) are the main cause for proximal junctional kyphosis (PJK), a complication of adult spinal deformity surgery. This study investigated risk factors for PJFx when performing long spinopelvic corrective fixation with lateral interbody fusion from T9 to ilium.

METHODS

This was a retrospective study of 43 patients with a minimum follow-up of 2 years. Radiographic measurements including thoracic kyphosis (TK), sagittal vertical axis (SVA), T1 pelvic angle (TPA), proximal junctional angle (PJA), lumbar lordosis (LL), lower LL, and pelvic tilt were measured preoperatively, one-month postoperatively, and at final follow up. TK and LL were also measured in a fulcrum backward-bending position preoperatively.

RESULTS

At final follow-up, PJK was found in 30/43 patients (69.8%); 20.9% of the cases had PJFx (9 patients). TPA (preoperative, and one-month postoperative) was significantly higher in the PJFx group than in the other groups. The differences in TPA, TK, and PJA between preoperative and one-month postoperative measurements in the PJFx group were significantly higher than those in the other groups. At final follow up, SVA was significantly higher in the PJFx group than in the "PJK without PJFx" group. TPA and TK were significantly higher in the PJFx group than in the other groups. PJA was significantly different between all groups.

CONCLUSION

Preoperative large TPA was the only risk factor for PJFx. Preoperative flexibility of the thoracolumbar spine and overcorrection of sagittal deformity were not related to PJFx or PJK.

Multicenter assessment of surgical outcomes in adult spinal deformity patients with severe global coronal malalignment: determination of target coronal realignment threshold

OBJECTIVE

The impact of global coronal malalignment (GCM; C7 plumb line-midsacral offset) on adult spinal deformity (ASD) treatment outcomes is unclear. Here, the authors' primary objective was to assess surgical outcomes and complications in patients with severe GCM, with a secondary aim of investigating potential surgical target coronal thresholds for optimal outcomes.

METHODS

This is a retrospective analysis of a prospective multicenter database. Operative patients with severe GCM (≥ 1 SD above the mean) and a minimum 2-year follow-up were identified. Demographic, surgical, radiographic, health-related quality of life (HRQOL), and complications data were analyzed.

RESULTS

Of 691 potentially eligible operative patients (mean GCM 4 ± 3 cm), 80 met the criteria for severe GCM ≥ 7 cm. Of these, 62 (78%; mean age 63.7 ± 10.7 years, 81% women) had a minimum 2-year follow-up (mean follow-up 3.3 ± 1.1 years). The mean ASD-Frailty Index was 3.9 ± 1.5 (frail), 50% had undergone prior fusion, and 81% had concurrent severe sagittal spinopelvic deformity with GCM and C7-S1 sagittal vertical axis (SVA) positively correlated (r = 0.313, p = 0.015). Surgical characteristics included posterior-only (58%) versus anterior-posterior (42%) approach, mean fusion of 13.2 ± 3.8 levels, iliac fixation (90%), 3-column osteotomy (36%), operative duration of 8.3 ± 3.0 hours, and estimated blood loss of 2.3 ± 1.7 L. Final alignment and HRQOL significantly improved (p < 0.01): GCM, 11 to 4 cm; maximum coronal Cobb angle, 43° to 20°; SVA, 13 to 4 cm; pelvic tilt, 29° to 23°; pelvic incidence-lumbar lordosis mismatch, 31° to 5°; Oswestry Disability Index, 51 to 37; physical component summary of SF-36 (PCS), 29 to 37; 22-Item Scoliosis Research Society Patient Questionnaire (SRS-22r) Total, 2.6 to 3.5; and numeric rating scale score for back and leg pain, 7 to 4 and 5 to 3, respectively. Residual GCM ≥ 3 cm was associated with worse SRS-22r Appearance (p = 0.04) and SRS-22r Satisfaction (p = 0.02). The minimal clinically important difference and/or substantial clinical benefit (MCID/SCB) was met in 43%-83% (highest for SRS-22r Appearance [MCID 83%] and PCS [SCB 53%]). The severity of baseline GCM (≥ 2 SD above the mean) significantly impacted postoperative SRS-22r Satisfaction and MCID/SCB improvement for PCS. No significant partial correlations were demonstrated between GCM or SVA correction and HRQOL improvement. There were 89 total complications (34 minor and 55 major), 45 (73%) patients with ≥ 1 complication (most commonly rod fracture [19%] and proximal junctional kyphosis [PJK; 18%]), and 34 reoperations in 22 (35%) patients (most commonly for rod fracture and PJK).

CONCLUSIONS

Study results demonstrated that ASD surgery in patients with substantial GCM was associated with significant radiographic and HRQOL improvement despite high complication rates. MCID improvement was highest for SRS-22r Appearance/Self-Image. A residual GCM ≥ 3 cm was associated with a worse outcome, suggesting a potential coronal realignment target threshold to assist surgical planning.

Validity of the global alignment proportion (GAP) score in predicting mechanical complications after adult spinal deformity surgery in elderly patients

PURPOSE

This study aimed to validate the usefulness of the global alignment proportion (GAP) score to predict postoperative mechanical failure in the elderly (mean age, 70.5 years) individuals with severe sagittal imbalance.

METHODS

A total of 84 patients were enrolled: mechanical complications (MC), minor mechanical complications (mMC), proximal junctional failure (PJF), and revision surgery occurred in 61% (51/84), 58% (49/84), 44% (37/84), and 13% (11/84) of the patients, respectively. The GAP score was calculated using the X-ray obtained in the early postoperative period. The validity of the GAP score's predictive ability was evaluated by calculating the area under the curve (AUC) of the receiver operating characteristics curve. Univariate logistic regression analysis and Cochran-Armitage test of trend were performed to determine the association between mechanical complications and GAP score.

RESULTS

The discriminatory power of GAP score to predict MC, mMC, and PJF was "moderately accurate," with an AUC of 0.839 (confidence interval [CI] 0.755-0.824, p < 0.001), 0.836 (CI 0.749-0.923, p < 0.001), and 0.702 (CI 0.588-0.851, p < 0.001), respectively. The GAP score showed a statistically significant association with MC, mMC, and PJF in univariate logistic regression analysis and Cochran-Armitage test for trend. However, it was not significantly associated with revision surgery.

CONCLUSION

This study showed promising results regarding the GAP score's predictive power for MC, mMC, and PJF in the elderly population with degenerative kyphoscoliosis. Using the GAP score, we can determine the patient's specific correction goal preoperatively to prevent mechanical failure based on individual patient's characteristics such as pelvic incidence.

Are Higher Global Alignment and Proportion Scores Associated With Increased Risks of Mechanical Complications After Adult Spinal Deformity Surgery? An External Validation

BACKGROUND

The Global Alignment and Proportion (GAP) score, based on pelvic incidence-based proportional parameters, was recently developed to predict mechanical complications after surgery for spinal deformities in adults. However, this score has not been validated in an independent external dataset.

QUESTIONS/PURPOSES

After adult spinal deformity surgery, is a higher GAP score associated with (1) an increased risk of mechanical complications, defined as rod fractures, implant-related complications, proximal or distal junctional kyphosis or failure; (2) a higher likelihood of undergoing revision surgery to treat a mechanical complication; and (3) is a lower (more proportioned) GAP score category associated with better validated outcomes scores using the Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22) and the Short Form-36 questionnaires?

METHODS

A total of 272 patients who had undergone corrective surgeries for complex spinal deformities were enrolled in the Scoli-RISK-1 prospective trial. Patients were included in this secondary analysis if they fulfilled the original inclusion criteria by Yilgor et al. From the original 272 patients, 14% (39) did not satisfy the radiographic inclusion criteria, the GAP score could not be calculated in 14% (37), and 24% (64) did not have radiographic assessment at postoperative 2 years, leaving 59% (159) for analysis in this review of data from the original trial. A total of 159 patients were included in this study,with a mean age of 58 ± 14 years at the time of surgery. Most patients were female (72%, 115 of 159), the mean number of levels involved in surgery was 12 ± 4, and three-column osteotomy was performed in 76% (120 of 159) of patients. The GAP score was calculated using parameters from early postoperative radiographs (between 3 and 12 weeks) including pelvic incidence, sacral slope, lumbar lordosis, lower arc lordosis and global tilt, which were independently obtained from a computer software based on centralized patient radiographs. The GAP score was categorized as proportional (scores of 0 to 2), moderately disproportional (scores of 3 to 6), or severely disproportional (scores higher than 7 to 13). Receiver operating characteristic area under curve (AUC) was used to assess associations between GAP score and risk of mechanical complications and risk of revision surgery. An AUC of 0.5 to 0.7 was classified as "no or low associative power", 0.7 to 0.9 as "moderate" and greater than 0.9 as "high". We analyzed differences in validated outcome scores between the GAP categories using Wilcoxon rank sum test.

RESULTS

At a minimum of 2 years' follow-up, a higher GAP score was not associated with increased risks of mechanical complications (AUC = 0.60 [95% CI 0.50 to 0.70]). A higher GAP score was not associated with a higher likelihood of undergoing a revision surgery to treat a mechanical complication (AUC = 0.66 [95% 0.53 to 0.78]). However, a moderately disproportioned GAP score category was associated with better SF-36 physical component summary score (36 ± 10 versus 40 ± 11; p = 0.047), better SF-36 mental component summary score (46 ± 13 versus 51 ± 12; p = 0.01), better SRS-22 total score (3.4 ± 0.8 versus 3.7 ± 0.7, p = 0.02) and better ODI score (35 ± 21 versus 25 ± 20; p = 0.003) than severely disproportioned GAP score category.

CONCLUSION

Based on the findings of this external validation study, we found that alignment targets based on the GAP score alone were not associated with increased risks of mechanical complications and mechanical revisions in patients with complex adult spinal disorders. Parameters not included in the original GAP score needed to be considered to reduce the likelihood of mechanical complications.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Mechanical revision following pedicle subtraction osteotomy: a competing risk survival analysis in 171 consecutive adult spinal deformity patients

STUDY DESIGN

Retrospective study.

OBJECTIVE

To report the incidence of revision surgery due to mechanical failure following pedicle subtraction osteotomy (PSO) in adult spinal deformity (ASD) patients. PSO allow major surgical correction of ASD, although; the risk of mechanical complications remains considerable. Previous reports have been based on smaller cohorts or multicenter databases and none have utilized competing risk (CR) survival analysis.

METHODS

All ASD patients undergoing PSO surgery from 2010 to 2015 at a single, tertiary institution were included. Demographics, long standing radiographs as well as intra- and postoperative complications were registered for all. A CR-model was used to estimate the incidence of revision surgery due to mechanical failure and two predefined multivariable models were used to assess radiographic prediction of failure and reported as odds ratios (OR) with 95% confidence intervals (95% CI).

RESULTS

A total of 171 patients were included with 2-year follow-up available for 91% (mean [IQR]: 35 [24-50] months). Mechanical failure occurred in 111 cases (65%) at any time in follow-up, the most frequent being rod breakage affecting 81 patients (47%). Cumulative incidence of revision surgery due to mechanical failure was estimated to 34% at 2 years and 58% at 5 years. A multivariable proportional odds model with death as competing risk showed significantly increased odds of revision with fusion to the sacrum (OR: 5.42; 95% CI 1.89-15.49) and preoperative pelvic tilt (PT) > 20° (OR: 2.41; 95% CI 1.13-5.16). History of previous surgery, number of instrumented vertebra, as well as postoperative SRS-Schwab modifiers and Global Alignment and Proportion score were not associated with significant effects on odds of revision.

CONCLUSIONS

In a consecutive single-center cohort of patients undergoing PSO for ASD, we found an estimated incidence of revision surgery due to mechanical failure of 34% 2 years postoperatively. Fusion to the sacrum and preoperative PT > 20° were associated with elevated risks of revision.

LEVEL OF EVIDENCE

Prognostic III.