Postoperative lordosis distribution index, patient reported outcome measures, and revision surgery following transforaminal lumbar interbody fusion.

Objective: Lordosis Distribution Index (LDI) is a new radiographic parameter associated with postoperative residual symptoms in patients undergoing Transforaminal Lumbar Interbody Fusion (TLIF). Recently, it has been applied on patients undergoing instrumented spine surgery, however not correlated to Patient Related Outcome Measures (PROMs). This study investigates whether the obtained the postoperative LDI after TLIF surgery correlates with the clinical outcome measured with PROMs. Methods: This study was based on prospectively obtained data in patients undergoing TLIF throughout 2017 at a Danish university hospital. Medical records and the DaneSpine Database were accessed to obtain preoperative, operative and follow-up data. Primary outcome was Oswestry Disability Index (ODI) 12 months postoperatively. Secondary outcomes included revision rate and additional PROMs. Results: 126 patients were included. 70 patients were classified with normolordosis (56 %), 42 hypolordosis (33 %) and 14 hyperlordosis (11 %). All groups experienced significant radiological changes undergoing surgery. Average reduction in ODI at 12 months postoperatively was -15.3 (±20.0). Minimally clinical important difference was achieved in 68 patients (54.0 %). No significant difference in PROMs between LDI-groups was observed in unadjusted or adjusted analyses. Revision surgery was performed in 8 patients with normolordosis (11.4 %), 7 hypolordosis (16.7 %) and 4 hyperlordosis (28.6 %). Conclusions: We found no significant correlation between postoperative LDI subgroups of normolordotic, hypo- or hyperlordotic patients and the clinical outcome of posterolateral fusion and TLIF surgery. A trend towards lower rate of revision surgery in the normolordotic group compared to the hypo- and hyperlordotic group was observed.

30-and 90-day readmissions in lumbar spine surgery. Differences in prevalence and causes.

BACKGROUND: The morbidity associated with surgical treatment of lumbar degenerative conditions has attracted increasing interest due to the economic impact on society, especially postoperative readmission. Limited studies have assessed this risk in a prospective, single-center consecutive fashion. OBJECTIVE: To assess the incidence and causes of 30- and 90-day unplanned readmission and revision surgery following surgical treatment for lumbar degenerative spine conditions at a tertiary treatment center. STUDY DESIGN: Prospective, single-center cohort study. METHODS: All patients undergoing degenerative lumbar spine surgery in a 1-year period from February 1st, 2016, were prospectively included. Patient characteristics, surgical information and information regarding postoperative complications, including readmission (30- and 90-days) and revision surgery were recorded. Readmissions were classified according to whether they were due to the surgical intervention specifically, or a medical complication. RESULTS: A total of 1399 patients underwent surgery for various lumbar degenerative pathologies in the study period and all were included. Of these, 9.4% (n = 132) were readmitted within 30 days of surgery and in some cases, multiple readmissions occurred (up to 3). The total 90-day readmission rate was 17.6%. Of these, 15% were related to the surgical procedure. The predominant medical related causes were systemic infection (30-day: 14.4%, 90-day: 10.7%), neurological symptoms (30-day: 6.3%, 90-day: 5.0%) and cardiovascular events (30-day: 8.1%, 90-day: 12.9%). The surgical related causes for readmission were pain (30-day: 13.1%, 90-day: 2.9%), wound complications (30-day: 11.3%, 90-day: 5.0% and re-herniation (30-day: 13.1%, 90-day: 2.9%). Age was the only factor with significant influence on readmission. CONCLUSION: The incidence of medical conditions causing unplanned 30-day readmissions following surgery for lumbar degenerative conditions, is significantly higher compared to readmissions related specifically to the surgical procedure. Examples of medical treatment included antibiotics, analgesics, laxatives, anticoagulants and beta blockers. The difference is even more pronounced for the 90-day readmissions. The predominant medical causes were systemic infections, neurological and cardiovascular events. Predominant causes related to the surgery were pain, wound complications and re-herniations. Readmissions may be reduced by optimizing the medical treatment and the pain management before discharge of the patient.

Demineralized cortical fibers are associated with a low pseudarthrosis rate in patients undergoing surgery for adult spinal deformity without three-column osteotomy.

Introduction: Following surgical treatment for adult spinal deformity (ASD) there is an increased risk of revision surgery due to mechanical failure or pseudarthrosis. Demineralized cortical fibers (DCF) were introduced at our institution aiming to reduce the risk of pseudarthrosis after ASD surgery. Research question: We wanted to investigate the effect of DCF on postoperative pseudarthrosis compared with allogenic bone graft in ASD surgery without three-column osteotomies (3CO). Materials & Methods: All patients undergoing ASD surgery between January 1, 2010 to June 31, 2020 were included in this interventional study with historical controls. Patients with current or previous 3CO were excluded. Before February 1, 2017, patients undergoing surgery received auto- and allogenic bone graft (non-DCF group) whilst patients after received DCF in addition to autologous bone graft (DCF group). Patients were followed for at least two years. The primary outcome was radiographic or CT-verified postoperative pseudarthrosis requiring revision surgery. Results: We included 50 patients in the DCF group and 85 patients in the non-DCF group for final analysis. Pseudarthrosis requiring revision surgery at two-year follow-up occurred in seven (14%) patients in the DCF group compared with 28 (33%) patients in the non-DCF group (p â€‹= â€‹0.016). The difference was statistically significant, corresponding to a relative risk of 0.43 (95%CI: 0.21-0.94) in favor of the DCF group. Conclusion: We assessed the use of DCF in patients undergoing ASD surgery without 3CO. Our results suggest that the use of DCF was associated with a considerable decreased risk of postoperative pseudarthrosis requiring revision surgery.

The Collateral Effect of Enhanced Recovery After Surgery Protocols on Spine Patients With Neuromuscular Scoliosis.

INTRODUCTION: Enhanced recovery after surgery (ERAS) protocols are often specific to a specific type of surgery without assessing the overall effect on the ward. Previous studies have demonstrated reduced length of stay (LOS) with ERAS protocols in patients with adolescent idiopathic scoliosis (AIS), although the patients are often healthy and with few or no comorbidities. In 2018, we used ERAS principles for patients undergoing AIS surgery with a subsequent 40% reduced LOS. The current study aims to assess the potential collateral effect of LOS in patients surgically treated for neuromuscular scoliosis admitted to the same ward and treated by the same staff but without a standardized ERAS protocol. METHODS: All patients undergoing neuromuscular surgery 2 years before and after ERAS introduction (AIS patients) with a gross motor function classification score of 4 to 5 were included. LOS, intensive care stay, and postoperative complications were recorded. After discharge, all complications leading to readmission and mortality were noted with a minimum of 2 years of follow-up using a nationwide registry. RESULTS: Forty-six patients were included; 20 pre-ERAS and 26 post-ERAS. Cross groups, there were no differences in diagnosis, preoperative curve size, pulmonary or cardiac comorbidities, weight, sex, or age. Postoperative care in the intensive care unit was unchanged between the two groups (1.2 vs 1.1; P = 0.298). When comparing LOS, we found a 41% reduction in the post-ERAS group (11 vs 6.5; P < 0.001) whereas the 90-day readmission rates were without any significant difference (45% vs 34% P = 0.22) We found no difference in the 2-year mortality in either group. CONCLUSION: The employment of ERAS principles in a relatively uncomplicated patient group had a positive, collateral effect on more complex patients treated in the same ward. We believe that training involving the caregiving staff is equally important as pharmacological protocols.

Complications Following Surgery for Adult Scheuermann's Kyphosis: A 2-Year Follow-Up in 22 Patients.

AIM: To determine the rate of postoperative complications following surgery for Scheuermann?s kyphosis (SK) and ascertain whether restoration to an ideal Roussouly spine type reduced the incidence of postoperative proximal junctional kyphosis (PJK). MATERIAL AND METHODS: We retrospectively screened all patients undergoing SK surgery at our institution (2010?2017) and excluded patients with less than two years of follow-up. Postoperative complications were identified as early or late and minor or major. Successful restoration of Roussouly spine type was assessed and patients were classified as ?restored? or ?non-restored.? Associations between ideal Roussouly restoration and postoperative PJK were evaluated using logistic regression analysis. RESULTS: The study included 22 patients with a median age of 23 (IQR, 20.0?43.8) years. Postoperative complications developed in 17 (77%) of these cases. All 17 patients developed minor complications; seven (32%) patients also exhibited major complications. PJK was diagnosed in 55% of the patients with an 18% overall two-year revision rate. Forty-four percent of the patients in the restored group developed PJK compared to 83% in the non-restored group (p=0.162). Multivariable logistic regression analysis revealed a trend towards an increased incidence of PJK in the non-restored group, albeit without statistical significance (OR, 9.4; 95% CI, 0.7?122.5, p=0.087). CONCLUSION: Our study revealed that 77% of patients undergoing surgery for SK developed at least one complication with a two-year revision rate of 18%. PJK was detected less frequently in patients who were restored to their ideal Roussouly spine type, although this finding did not achieve statistical significance.

Is preoperative S-albumin associated to postoperative complications and readmission in patients with adult spinal deformity: a prospective analysis of 128 patients using the Spine AdVerse Event Severity (SAVES) system.

PURPOSE: To assess the association between preoperative S-albumin and postoperative outcome following adult spinal deformity (ASD) surgery. METHODS: All patients undergoing ASD surgery from February 1, 2017 and January 31, 2018 at a single quaternary referral center were prospectively included. Adverse events (AE) during admission were assessed using the Spine AdVerse Events Severity (SAVES) system. Based on preoperative S-albumin, patients were categorized as "normal" or "abnormal" and compared regarding postoperative outcome, adverse events (AEs), 30- and 90-day readmission, revision surgery, and mortality. RESULTS: A total of 128 patients aged ≥ 18 years were included, and S-albumin was available in 88%. Of these, 73% (n = 93) were classified as "normal", 16% (n = 20) as "abnormal", and 12% (n = 15) as "missing". The "normal" albumin group had less comorbidity burden [ASA score 2 (2, 3) vs 3 (2, 3), p = 0.011], higher hemoglobin levels (8.4 (± 0.9) mmol/L vs 7.4 (± 1.1) mmol/L, p < 0.001), and higher S-albumin (38.9 (± 2.7) g/L vs 31.9 (± 4.4) g/L, < 0.001). The rate of 90-day readmission was significantly increased in the "abnormal" group (65% vs 36%), corresponding to a relative risk increase of 1.25 (95% CI 1.02-1.52, p = 0.029). Similar increased risks were found in subsequent logistic regression analyses, although results were not significant in multivariable analysis (p = 0.102). Comparing remaining outcome parameters, point estimates revealed increased AEs, 30-day readmission, and revision in the "abnormal" albumin group, although effects did not reach statistical significance. CONCLUSIONS: In a prospective, consecutive, single-center cohort of 128 patients undergoing ASD surgery, we found a significant association between "abnormal" preoperative S-albumin and increased 90-day readmission. Furthermore, although the findings were not statistically significant, we did find that AEs, 30-day readmission, and revision were numerically more frequent in the "abnormal" group, suggesting an expected tendency that should be further investigated. We conclude that nutritional status prior to ASD surgery could be important to consider and suggest validation in larger prospective cohorts. LEVEL OF EVIDENCE: Prognostic II.

Rapid Discharge Protocol Reduces Length of Stay and Eliminates Postoperative Nausea and Vomiting After Surgery for Adolescent Idiopathic Scoliosis.

BACKGROUND: Implementing standardized pathways following adolescent idiopathic scoliosis surgery have been shown to reduce length of stay (LOS). However, controversies still exist. This applies especially to the transition to solid foods, postoperative pruritus, and postoperative nausea and vomiting (PONV). The aim of this proposed protocol is to present an option to reduce these factors while reducing the LOS. METHODS: The protocol was designed with reduction of morphine. One-hundred and eight patients were included in this study, including 66 controls before intervention. All patients underwent posterior scoliosis surgery. All patients were scored daily using a numeric rating scale, and they noted if any nausea, vomiting, or pruritus was present. All medications were recorded. For every 20 patients included, the steering committee met to identify any implementation issues. RESULTS: LOS was reduced from 6.3 to 3.6 days (43% reduction, P = 0.003). PONV was reduced from affecting 82% to 9% of patients (P < 0.0001). The number of patients experiencing postoperative pruritus was reduced from 40% to 2% (P < 0.001). Time spent in postoperative recovery was reduced from 278 (117 - 470) minutes to 199 (128 - 643), P < 0.001. Patients' pain scores remained unchanged compared with controls (mean 4 [3 - 8]). We found no adverse effects of solid food intake from postoperative day 0. CONCLUSIONS: We found a significant reduction in length of stay, PONV, and pruritus after implementation of the protocol. This allowed for no restrictions in regards to solid food intake postoperatively.

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.

Lordosis Distribution Index in Short-Segment Lumbar Spine Fusion - Can Ideal Lordosis Reduce Revision Surgery and Iatrogenic Deformity?

OBJECTIVE: The demand for spinal fusion is increasing, with concurrent reports of iatrogenic adult spinal deformity (flatback deformity) possibly due to inappropriate lordosis distribution. This distribution is assessed using the lordosis distribution index (LDI) which describes the upper and lower arc lordosis ratio. Maldistributed LDI has been associated to adjacent segment disease following interbody fusion, although correlation to later-stage deformity is yet to be assessed. We therefore aimed to investigate if hypolordotic lordosis maldistribution was associated to radiographic deformity-surrogates or revision surgery following instrumented lumbar fusion. METHODS: All patients undergoing fusion surgery ( ≤ 4 vertebra) for degenerative lumbar diseases were retrospectively included at a single center. Patients were categorized according to their postoperative LDI as: "normal" (LDI 50-80), "hypolordotic" (LDI < 50), or "hyperlordotic" (LDI > 80). RESULTS: We included 149 patients who were followed for 21 ± 14 months. Most attained a normally distributed lordosis (62%). The hypolordotic group had increased postoperative pelvic tilt (PT) (p < 0.001), pelvic incidence minus lumbar lordosis (PI-LL) mismatch (p < 0.001) and decreased global lordosis (p = 0.007) compared to the normal group. Survival analyses revealed a significant difference in revision surgery (p = 0.03), and subsequent multivariable logistic regression showed increased odds of 1-year revision in the hypolordotic group (p = 0.04). There was also a negative, linear correlation between preoperative pelvic incidence (PI) and postoperative LDI (p < 0.001). CONCLUSION: In patients undergoing instrumented lumbar fusion surgery, hypolordotic lordosis maldistribution (LDI < 50) was associated to increased risk of revision surgery, increased postoperative PT and PI-LL mismatch. Lordosis distribution should be considered prior to spinal fusion, especially in high PI patients.

A Comparison of Mortality and Morbidity Between Complex and Degenerative Spine Surgery in Prospectively Collected Data From 2,280 Procedures.

OBJECTIVE: The reported incidence of complications and/or adverse events (AEs) following spine surgery varies greatly. A validated, systematic, reproducible reporting system to quantify AEs was used in 2 prospective cohorts, from 2 spine surgery centers, conducting either complex or purely degenerative spine surgery; in a comparative fashion. The aim was to highlight the differences between 2 distinctly different prospective cohorts with patients from the same background population. METHODS: AEs were registered according to the predefined AE variables in the SAVES (Spine AdVerse Events Severity) system which was used to record all intra- and perioperative AEs. Additional outcomes, including mortality, length of stay, wound infection requiring revision, readmission, and unplanned revision surgery during the index admission, were also registered. RESULTS: A total of 593 complex and 1,687 degenerative procedures were consecutively included with 100% data completion. There was a significant difference in morbidity when comparing the total number of AEs between the 2 groups (p < 0.001): with a mean number of 1.42 AEs per patient (n = 845) in the complex cohort, and 0.97 AEs per patient (n = 1,630) in the degenerative cohort. CONCLUSION: In this prospective study comparing 2 cohorts, we report the rates of AEs related to spine surgery using a validated reproducible grading system for registration. The rates of morbidity and mortality were significantly higher following complex spine surgery compared to surgery for degenerative spine disease.

Intraoperative traction in neuromuscular scoliosis surgery improves major curve correction when fusing to L5.

BACKGROUND: Intraoperative traction has shown improved curve correction in neuromuscular scoliosis surgery. It is found to be superior to anterior release in terms of correction of both main curve and pelvic obliquity. No previous study has examined the effect of intraoperative traction in patients without pelvic fixation. METHOD: This retrospective study included 40 non-ambulatory (GMFCS 4 or above) patients with neuromuscular scoliosis undergoing surgery with bilateral segmental pedicle screw instrumentation to L5. Twenty-two consecutive patients had intraoperative Gardner-Wells tongs and skin traction (traction group), while the remaining did not (non-traction group). Inclusion criteria were minimum 2-year follow-up, complete medical records and radiographs. Main curve (MC), pelvic obliquity (POB), T1 tilt, kyphosis, rotation, coronal and sagittal balance and preoperative bending radiographs were measured and analyzed in all patients. RESULTS: Both groups demonstrated roughly 60% MC correction. Preoperative MC was larger in the traction group [97° (49-126) vs. 83° (40-134); P = 0.03]. The measured correction index was almost twice as large in the traction group (1.9 vs. 1.1; P = 0.001). Mean [IQR] 2-year POB was 14° [7-40] in the traction group compared to 16° [4-60] in the non-traction group (P = 0.59). Eleven patients (50%) in the traction group compared to only four (22%) in the non-traction group had a POB within 10° at 2-year follow up (RR: 2.1; 95% CI 0.8-5.2). We found no difference in kyphosis or remaining radiographic parameters. No traction-related complications were recorded. CONCLUSION: In patients with neuromuscular scoliosis undergoing instrumented fusion to the L5, we found that intraoperative traction increased the degree of MC correction and patients were more likely to achieve POB below 10° without any effects on sagittal parameters or without any detectable significant reduction on rotation.

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.

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.

Morbidity and mortality following degenerative spine surgery in a prospective cohort of 1687 consecutive surgical procedures.

STUDY DESIGN: Prospective, observational cohort study. OBJECTIVE: To determine the true incidence of adverse events (AEs) in European adults undergoing surgery for degenerative spine diseases. The majority of surgeries performed for degenerative spinal diseases are elective, and the need for adequate estimation of risk-benefit of the intended surgery is imperative. A cumbersome obstacle for adequate estimation of surgery-related risks is that the true incidence of complications or adverse events (AEs) remains unclear. METHODS: All adult patients (≥ 18 years) undergoing spine surgery at a single center from February 1, 2016, to January 31, 2017, were prospectively and consecutively included. Morbidity and mortality were determined using the Spine AdVerse Events Severity (SAVES) system. Additionally, the correlation between the AEs and length of stay (LOS) and mortality was assessed. RESULTS: A total of 1687 procedures were performed in the study period, and all were included for analysis. Of these, 1399 (83%) were lumbar procedures and 288 (17%) were cervical. The overall incidence of AEs was 47.4%, with a minor AE incidence of 43.2% and a major of 14.5%. Female sex (OR 1.5 [95% CI 1.2-1.9), p < 0.001) and age > 65 years (OR 1.5 [95% CI 1.1-1.7], p = 0.012) were significantly associated with increased odds of having an AE. CONCLUSION: Based on prospectively registered AEs in this single-center study, we validated the use of the SAVES system in a European population undergoing spine surgery due to degenerative spine disease. We found a higher incidence of AEs than previously reported in retrospective studies. The major AEs registered occurred significantly more often perioperatively and in patients > 65 years.

Revision surgery and mortality following complex spine surgery: 2-year follow-up in a prospective cohort of 679 patients using the Spine AdVerse Event Severity (SAVES) system.

STUDY DESIGN: Prospective study. OBJECTIVE: To determine the 2-year risk of revision surgery and all-cause mortality after complex spine surgery, and to assess if prospectively registered adverse events (AE) could predict either outcome. Revision surgery and mortality are serious complications to spine surgery. Previous studies of frequency have mainly been retrospective and few studies have employed competing risk survival analyses. In addition, assessment of predictors has focused on preoperative patient characteristics. The effect of perioperative AEs on revision and all-cause mortality risks are not fully understood. METHODS: Between January 1 and December 31, 2013, we prospectively included all patients undergoing complex spine surgery at a single, tertiary institution. Complex spine surgery was defined as conditions deemed too complicated for surgery at a secondary institute, or patients with severe comorbidities requiring multidisciplinary observation and treatment. AEs were registered using the Spine Adverse Event Severity system and patients were followed for minimum 2 years regarding revision surgery and all-cause mortality. Incidences were estimated using competing risk survival analyses and correlation between AEs and either outcome was assessed using proportional odds models. RESULTS: We included a complete and consecutive cohort of 679 adult and pediatric patients. Demographics, surgical data, AEs, and events of revision or all-cause mortality were registered. The cumulative incidence of 2-year all-cause revision was 19% (16-22%) and all-cause mortality was 15% (12-18%). Deformity surgery was the surgical category with highest incidence of revision and the highest incidence of all-cause mortality was seen in the tumor group. Across surgical categories, cumulative incidences of 2-year revision ranged between 11% (tumor) and 33% (deformity), whilst 2-year all-cause mortality ranged between 3% (deformity) and 33% (tumor). We found that major intraoperative AEs were associated to increased odds of revision. Deep wound infection was associated to increased odds of all-cause mortality. CONCLUSIONS: We report the cumulative incidences of revision surgery and all-cause mortality following complex spine surgery. We found higher incidences of revision compared to previous retrospective studies. Prospectively registered AEs were correlated to increased odds of revision surgery and all-cause mortality. These results may serve as reference for future interventional studies and aid in identifying at-risk patients. LEVEL OF EVIDENCE: I.

Surgical correction of Adult Spinal Deformity in accordance to the Roussouly classification: effect on postoperative mechanical complications.

STUDY DESIGN: Single-center, retrospective. OBJECTIVES: To assess the restoration of ideal sagittal spine shape in accordance to the Roussouly classification and the effect on postoperative mechanical complications. Surgical correction of Adult Spinal Deformity is both challenging and complex. The risk of postoperative complications is considerable, especially mechanical complications requiring revision surgery. Attention has been directed toward defining alignment targets in attempts to minimize these risks, and the Roussouly classification has been proposed as a potential surgical aim. METHODS: All patients undergoing ASD surgery from 2013-2016 were included at a single, quaternary institute. Successful restoration of Roussouly spine shape was retrospectively assessed, and patients were classified as either "restored" or "non-restored". Cumulative incidence of revision surgery due to mechanical failure was estimated using the Aalen-Johansen estimator, with death as the competing risk. A multivariable proportional odds model was used to estimate the effect of the Roussouly algorithm on revision surgery due to mechanical failure. RESULTS: We identified a complete and consecutive cohort of 233 patients who were followed for a mean period of 36 (± 14) months. The 2-year cumulative incidence of revision surgery was 28%. Comparing the "restored" to the "non-restored" group, the overall revision rates were high in both groups. However, when adjusting for known cofounders in a multivariable proportional odds analysis, there was an almost fivefold increased odds of revision due to mechanical failure in the "non-restored" group (p = 0.036). CONCLUSION: Surgical correction of ASD in accordance to the ideal Roussouly spine shape was correlated to a marked and significant decrease in risk of revision surgery due to mechanical failure. Nonetheless, the overall revision risk was elevated in both groups. LEVEL OF EVIDENCE: Therapeutic III.

Readmission following complex spine surgery in a prospective cohort of 679 patients - 2-years follow-up using the Spine AdVerse Event Severity (SAVES) system.

BACKGROUND CONTEXT: Recent studies suggest that prospective registration more accurately reflects the true incidence of adverse events (AEs). To our knowledge, no previous study has investigated prospectively registered AEs' influence on hospital readmission following spine surgery. PURPOSE: To determine the frequency and type of unplanned readmissions after complex spine surgery, and to investigate if prospectively registered AEs can predict readmissions. DESIGN: This is a prospective, consecutive cohort study. PATIENT SAMPLE: We conducted a single-center study of 679 consecutive patients who underwent complex spine surgery defined as conditions deemed too complicated for surgery at a secondary institute, or patients with severe comorbidities requiring multidisciplinary observation and treatment. OUTCOME MEASURES: The outcomes in this study were (1) readmission to any hospital department within 30 days of discharge and (2) readmission to a surgical spine center at any time in follow-up. METHODS: All patients undergoing complex spine surgery, at our tertiary referral center, were consecutively, and prospectively, included from January 1 to December 31, 2013. Demographics and perioperative AEs were registered using the Spine AdVerse Events Severity (SAVES) system. Patients were followed for a minimum of two years. A competing risk survival model was used to estimate rates of readmissions with death as a competing risk. Patient characteristics, surgical parameters and perioperative AEs were analyzed to identify factors associated with readmission. Analyses of 30-day readmission were performed using logistic regression models. A proportional odds model, with death as competing risk, was used for readmissions to a spine center at any time in follow-up. Results were reported as odds ratios with 95% confidence intervals (95% CI). RESULTS: Within 2 years of index discharge, 443 (65%) were readmitted. Only 20% of readmissions were to a spine center. Cumulative incidence (95% CI) of readmission was estimated to 13% (10%-16%) at 30 days, 26% (23%-30%) at 90 days, 50% (46%-54%) at 1 year, and 59% (55%-63%) at 2 years following discharge. Rates were markedly lower for readmissions to a spine center. Increased odds of 30-day readmission were correlated to intraoperative hypotension (p=.02) and major intraoperative blood loss (p<.01). Readmission to a spine center was associated with the number of instrumented vertebrae (p=.047), major intraoperative AE (p=.01), and intraoperative hypotension (p<.01). CONCLUSIONS: To the best of our knowledge, this is the first study to analyze prospectively registered AEs' association to readmission up to 2 years after complex spine surgery. We found that readmissions were more frequent than previously reported when including readmissions to any department or hospital. Factors related to major intraoperative blood loss were associated to increased odds of readmission. This should be considered during planning of postoperative observation and care.

Mechanical complications in adult spinal deformity and the effect of restoring the spinal shapes according to the Roussouly classification: a multicentric study.

PURPOSE: To evaluate the incidence of mechanical complications in patients with adult spine deformity (ASD) treated by restoring the normal shape according to the Roussouly classification. METHODS: This is a retrospective multicentric study with a minimum follow-up of 2 years. Patients operated on with fusion for ASD (minimum performed fusion: L2 to sacrum) were included. Patients with a history of previous spinal fusion of more than three levels were excluded. Spinal and pelvic parameters were measured on the preoperative and the immediate postoperative follow-up. All mechanical complications were recorded. RESULTS: A total of 290 patients met the criteria of inclusion with a minimum follow-up of 2 years. Mechanical complications occurred in 30.4% of the cohort. The most common complication was PJK with an incidence of 18% while nonunion or instrumentation failure (rod breakage, implant failure) occurred in 12.4%. 66% of the patients were restored to the normal shape according to the Roussouly classification based on their PI and had a mechanical complication rate of 22.5%, whereas the remaining 34% of patients had a complication rate of 46.8% (p < 0.001). The relative risk for developing a mechanical complication if the algorithm was not met was 3 (CI 1.5-4.3; p < 0.001) CONCLUSION: In the recent literature, there are no clear guidelines for ASD correction. Restoring the sagittal spinal contour to the normal shapes of Roussouly according to the PI could serve as a guideline for ASD treatment. Ignoring this algorithm has a threefold risk of increased mechanical complications. We recommend this algorithm for treatment of ASD. LEVEL OF EVIDENCE: IV cross-sectional observational study. These slides can be retrieved under Electronic Supplementary Material.

Spinopelvic Parameters Depending on the Angulation of the Sacral End Plate Are Less Reproducible Than Other Spinopelvic Parameters in Adult Spinal Deformity Patients.

STUDY DESIGN: Reproducibility study. OBJECTIVES: To report the agreement and reliability for commonly used sagittal plane measurements. SUMMARY OF BACKGROUND DATA: Spinopelvic parameters and sagittal vertical axis (SVA) are commonly used parameters for preoperative planning and postoperative evaluation of patients with adult spinal deformity (ASD). Previous reproducibility studies have focused on describing the reliability using intraclass correlation coefficients (ICCs), thus quantifying the methods' ability to distinguish between individuals. To our knowledge, no previous study in patients with ASD has reported the measurement error in terms of limits of agreement. The current study aimed to report the agreement and reliability for measurements of pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and SVA in ASD patients. METHODS: In a consecutive, one-center cohort of 64 patients referred for ASD evaluation, a blinded test-retest study was performed. Reliability was assessed using ICCs, whereas 95% limits of agreement (LOAs) were used to quantify agreement. RESULTS: We found "excellent" (ICC > 0.9) results in all analyses of reliability except for interrater PI, which was classified as "good" (ICC = 0.89). However, considerable interrater measurement error was observed for parameters depending on the angulation of the sacral end plate (95% LOA of ±11° and ±14° for SS and PI, respectively) compared with ±5° for PT and ±7 mm for SVA, which depends on the location of the sacral end plate. Intrarater agreement was only slightly better. CONCLUSION: These are to our knowledge the first estimates of measurement error for sagittal spinopelvic parameters in ASD patients. Despite near excellent ICCs, we found considerable measurement error for parameters depending on the angulation rather than the location of the sacral end plate. LEVEL OF EVIDENCE: Level II.

Moderate Interrater and Substantial Intrarater Reproducibility of the Roussouly Classification System in Patients With Adult Spinal Deformity.

STUDY DESIGN: Reproducibility study of a classification system. OBJECTIVES: To provide the inter- and intrarater reproducibility of the Roussouly Classification System in a single-center prospective cohort of patients referred for Adult Spinal Deformity. SUMMARY OF BACKGROUND DATA: The Roussouly Classification System was developed to describe the variation in sagittal spine shape in normal individuals. A recent study suggests that patients' spine types could influence the outcome following spinal surgery. The utility of a classification system depends largely on its reproducibility. METHODS: Sixty-four consecutive patients were included in a blinded test-retest setting using digital radiographs. All ratings were performed by four spine surgeons with different levels of experience. There was a 14-day interval between the two reading sessions. Inter- and intrarater reproducibility was calculated using Fleiss Kappa and crude agreement percentages. RESULTS: We found moderate interrater (κ = 0.60) and substantial intrarater (κ = 0.68) reproducibility. All 4 raters agreed on the Roussouly type in 47% of the cases. The most experienced rater had significantly higher intrarater reliability compared to the least experienced rater (κ = 0.57 vs 0.78). The two most experienced raters also had the highest crude agreement percentage (75%); however, they also had a significant difference in distribution of spine types. CONCLUSION: The current study presents moderate interrater and substantial intrarater reliability of the Roussouly Classification System. These findings are acceptable and comparable to previous results of reproducibility for a classification system in patients with Adult Spinal Deformity. Additional studies are requested to validate these findings as well as to further investigate the impact of the classification system on outcome following surgery.