Complications and Avoidance in Adult Spinal Deformity Surgery

Adult spinal deformity (ASD) is a complex disease that can result in significant disability. Although surgical treatment has been shown to be of benefit, the complication rate in the perioperative and postoperative periods can be as high as 70%. Some of the most common complications of ASD surgery include intraoperative cerebrospinal fluid leak, high blood loss, new neurologic deficit, hardware failure, proximal junctional kyphosis/failure, pseudarthrosis, surgical site infection, and medical complications. For each of these complications, one or more strategies can be utilized to avoid and/or minimize the consequences.

Proximal Junctional Failure in Adult Spinal Deformity Surgery: An In-depth Review

Adult spinal deformity (ASD) surgery aims to correct abnormal spinal curvature in adults, leading to improved functionality and reduced pain. However, this surgery is associated with various complications, one of which is proximal junctional failure (PJF). PJF can have a significant impact on a patient's quality of life, necessitating a comprehensive understanding of its causes and the development of effective management strategies. This review aims to provide an in-depth understanding of PJF in ASD surgery. PJF is a complex complication resulting from a multitude of factors including patient characteristics, surgical techniques, and postoperative management. Age, osteoporosis, overcorrection of sagittal alignment, and poor bone quality are identified as significant risk factors. The clinical implications of PJF are substantial, often requiring revision surgery and causing a considerable decrease in patients' quality of life. Prevention strategies include careful preoperative planning, appropriate patient selection, and optimization of surgical techniques. Treatment often necessitates a multifaceted approach, including surgical intervention and the management of underlying risk factors. Predictive modeling is an emerging field that may offer a promising avenue for the risk stratification of patients and individualized preventive strategies. A thorough understanding of PJF's pathogenesis, risk factors, and clinical implications is essential for surgeons involved in ASD surgery. Current preventive measures and treatment strategies aim to mitigate the risk and manage the complications of PJF, but the complication cannot be entirely prevented. Future research should focus on the development of more effective preventive and treatment strategies, and predictive models could be valuable in this pursuit.

Effect of corrective stresses on rods in adult spinal deformity surgery-finite element analysis

BACKGROUND

The incidence of rod fracture after corrective surgery for adult spinal deformity (ASD) is high. Although many reports have investigated the effects of rod bending considering postoperative body motion, and countermeasures, there are no reports investigating the effects during intraoperative correction. The purpose of this study was to investigate the effect of ASD correction on rods by using finite element analysis (FEA) based on the rod shape changes before and after spinal corrective fusion.

METHODS

Five ASD patients (mean age 73 years, all female) who underwent thoracic to pelvic fusion were included in this study. A 3D rod model was created using computer-aided design software from digital images of the intraoperatively bended rod and intraoperative X-ray images after corrective fusion. The 3D model of the bent rod was meshed by dividing each of the screw head intervals into 20 sections and cross-section of the rod into 48 sections. Two surgical fusion methods of stepwise fixation as the cantilever method and parallel fixation as the translational method were simulated to evaluate stress and bending moments on the rods during intraoperative correction.

RESULTS

The stresses on the rods were 1500, 970, 930, 744, and 606 MPa in the five cases for stepwise fixation and 990, 660, 490, 508, and 437 MPa for parallel fixation, respectively, with parallel fixation having lower stresses in all cases. In all cases, maximum stress was found around the apex of the lumbar lordosis and near L5/S1. The bending moment was high around L2-4 in most cases.

CONCLUSIONS

The external forces of intraoperative correction had the greatest effect on the lower lumbar region, especially around the apex of the lumbar lordosis.

S2 alar-iliac screw loosening as a preventive factor for hip joint osteoarthritis after adult spinal deformity surgery: a case-control study

PURPOSE

This study aimed to evaluate the progression of hip pathology and risk factors after ASD surgery.

METHODS

This case-control study enrolled 123 patients (246 hips); seven hips underwent hip arthroplasty were excluded. We measured the center-edge (CE) angle, joint space width (JSW), and Kellgren-Lawrence (KL) grade. We defined a CE angle˂25° as developmental dysplasia of the hip (DDH). We evaluated S2 alar-iliac (AI) screw loosening at final follow-up.

RESULTS

The annual decrease in the JSW was 0.31 mm up to 1 year, and 0.13 mm after 1 year (p = 0.001). KL grade progression occurred in 24 hips (10.0%; group P), while no progression occurred in 215 (90.0%; group N) hips. Nonparametric analysis between groups P and N revealed that significant differences were observed in sex, DDH, KL grade, ratio of S2AI screw fixation at baseline, and ratio of S2AI screw loosening at final follow-up. Multiple logistic regression analysis revealed that DDH (p = 0.018, odds ratio (OR) = 3.0, 95%CI = 1.2-7.3), baseline KL grade (p < 0.0001, OR = 37.7, 95%CI = 7.0-203.2), and S2AI screw fixation (p = 0.035, OR = 3.4, 95%CI = 1.1-10.4) were significant factors. We performed sub-analysis to elucidate the relationship between screw loosening and hip osteoarthritis in 131 hips that underwent S2AI screw fixation. Non-loosening of the S2AI screw was a significant factor for KL grade progression (p < 0.0001, OR = 8.9, 95%CI = 3.0-26.4).

CONCLUSION

This study identified the prevalence and risk factors for the progression of hip osteoarthritis after ASD surgery. Physicians need to pay attention to the hip joint pathology after ASD surgery.

Reaching the medicare allowable threshold in adult spinal deformity surgery: multicenter cost analysis comparing actual direct hospital costs versus what the government will pay

STUDY DESIGN

Retrospective multicenter cost analysis.

OBJECTIVE

To (1) determine if index episode of care (iEOC) costs of Adult Spinal Deformity (ASD) surgeries are below the Medicare Allowable (MA) threshold, and (2) identify variables that can predict iEOC cases that are below MA. Previous studies have suggested that actual direct hospital cost of Adult Spinal Deformity (ASD) surgery is higher than Medicare Allowable (MA) rates, which has become the benchmark reimbursement target for hospital accounting systems.

METHODS

From a prospective, multicenter ASD surgical database, patients undergoing long instrumented fusions (> 5 level) with cost data were identified. iEOC cost was calculated utilizing actual direct hospital cost. MA rates were calculated using hospital specific, year-appropriate CMS Inpatient Pricer Payment System. Recursive partitioning identified potentially modifiable variables that can predict iEOC cost < MA.

RESULTS

Administrative direct cost data from 210 patients were obtained from 4 of 11 centers. Ninety-five (45%) patients had iEOC cost < MA. There was significant variation across the four centers in both iEOC cost ($56,788-$78,878, p < 0.0001) and reimbursement ($40,623-$91,351, p < 0.0001) across deformity-specific DRGs (453,454,456,457). Academic centers were more likely to have iEOC costs < MA (67.2% vs 8.9%, p < 0.0001). Recursive partitioning (r² = 0.309) identified rhBMP-2 use of < 24 mg, sagittal plane deformity, a combined anterior/posterior approach, and an SF36-MCS < 39 as predictive for iEOC cost < MA. Performing an anterior/posterior approach reimburses between 14.7% and 121.1% more (2.2-fold) than posterior-only approach. This change in DRG allows iEOC cost to be more likely below the MA threshold.

CONCLUSION

There is significant institutional (private vs academic) variation in ASD reimbursement. BMP use, deformity type, approach, and baseline mental health impact ASD surgery cost being below Medicare reimbursement. ASD surgeries with anterior/posterior approaches are in DRGs that can potentially reimburse 2.2-fold the posterior-only surgery, making it more likely to fall below the MA threshold.

LEVEL OF EVIDENCE

III.

A Novel Weave Tether Technique for Proximal Junctional Kyphosis Prevention in 71 Adult Spinal Deformity Patients: A Preliminary Case Series Assessing Early Complications and Efficacy

BACKGROUND

Proximal junctional kyphosis (PJK) rates may be as high as 69.4% after adult spinal deformity (ASD) surgery. PJK is one of the greatest unsolved challenges in long-segment fusions for ASD and remains a common indication for costly and impactful revision surgery. Junctional tethers may help to reduce the occurrence of PJK by attenuating adjacent-segment stress.

OBJECTIVE

To report our experience and assess early safety associated with a novel "weave-tether technique" (WTT) for PJK prophylaxis in a large series of patients.

METHODS

This single-center retrospective study evaluated consecutive patients who underwent ASD surgery including WTT between 2017 and 2018. Patient demographics, operative details, standard radiographic measurements, and complications were analyzed.

RESULTS

A total of 71 patients (mean age 66 ± 12 yr, 65% women) were identified. WTT included application to the upper-most instrumented vertebrae (UIV) + 1 and UIV + 2 in 38(53.5%) and 33(46.5%) patients, respectively. No complications directly attributed to WTT usage were identified. For patients with radiographic follow-up (96%; mean duration 14 ± 12 mo), PJK occurred in 15% (mean 1.8 ± 1.0 mo postoperatively). Proximal junctional angle increased an average 4° (10° to 14°, P = .004). Rates of symptomatic PJK and revision for PJK were 8.8% and 2.9%, respectively.

CONCLUSION

Preliminary results support the safety of the WTT for PJK prophylaxis. Approximately 15% of patients developed radiographic PJK, no complications were directly attributed to WTT usage, and the revision rate for PJK was low. These early results warrant future research to assess longer-term efficacy of the WTT for PJK prophylaxis in ASD surgery.

The Scoli-RISK 1 results of lower extremity motor function 5 years after complex adult spinal deformity surgery

INTRODUCTION

Neurologic complications after complex adult spinal deformity (ASD) surgery are important, yet outcomes are heterogeneously reported, and long-term follow-up of actual lower extremity motor function is unknown.

OBJECTIVE

To prospectively evaluate lower extremity motor function scores (LEMS) before and at 5 years after surgical correction of complex ASD.

DESIGN

Retrospective analysis of a prospective, multicenter, international observational study.

METHODS

The Scoli-RISK-1 study enrolled 272 ASD patients undergoing surgery from 15 centers around the world. Inclusion criteria were Cobb angle of > 80°, corrective osteotomy for congenital or revision deformity and/or 3-column osteotomy. Among patients with 5-year follow-up, comparisons of LEMS to baseline and within each follow-up period were made via documented neurologic exams on each patient.

RESULTS

Seventy-seven (28.3%) patients had 5-year follow-up. Among these 77 patients with 5-year follow-up, rates of postoperative LEMS deterioration were: 14.3% hospital discharge, 10.7% at 6 weeks, 6.5% at 6 months, 9.5% at 2 years and 9.3% at 5 years postoperative. During the 2-5 year window, while mean LEMS did not change significantly (-0.5, p = 0.442), eight (11.1%) patients deteriorated (of which 3 were ≥ 4 motor points), and six (8.3%) patients improved (of which 2 were ≥ 4 points). Of the 14 neurologic complications, four (28.6%) were surgery-related, three of which required reoperation. While mean LEMS were not impacted in patients with a major surgery-related complication, mean LEMS were significantly lower in patients with neurologic surgery-related complications at discharge (p = 0.041) and 6 months (p = 0.008) between the two groups as well as the change from baseline to 5 years (p = 0.041).

CONCLUSIONS

In 77 patients undergoing complex ASD surgery with 5-year follow-up, while mean LEMS did not change from 2 to 5 years, subtle neurologic changes occurred in approximately 1 in 5 patients (11.1% deteriorated; 8.3% improved). Major surgery-related complication did not result in decreased LEMS; however, those with neurologic surgery-related complications continued to have decreased lower extremity motor function at 5 years postoperative. These results underscore the importance of long-term follow-up to 5 years, using individual motor scores rather than group averages, and comparing outcomes to both baseline and last follow-up.

Adjacent segment disease on hip joint as a complication of spinal fusion surgery including sacroiliac joint fixation

PURPOSE

Recently, the number of adult spinal deformity surgeries including sacroiliac joint fixation (SIJF) by using an S2 alar iliac screw or iliac screw has increased to avoid the distal junctional failure. However, we occasionally experienced patients who suffered from hip pain after a long instrumented spinal fusion. We hypothesized that long spinal fusion surgery including SIJF influenced the hip joint as an adjacent joint. The aim of this paper was to evaluate the association between spinal deformity surgery including SIJF and radiographic progression of hip osteoarthritis (OA).

METHODS

This study was retrospective cohort study. In total, 118 patients who underwent spinal fusion surgery at single center from January 2013 to August 2018 were included. We measured joint space width (JSW) at central space of the hip joint. We defined reduction of more than 0.5 mm/year in JSW as hip OA progression. The patients were divided into two groups depending on either a progression of hip osteoarthritis (Group P), or no progression (Group N).

RESULTS

The number of patients in Group P and Group N was 47 and 71, respectively. Factor that was statistically significant for hip OA was SIJF (p = 0.0065, odds ratio = 7.1, 95% confidence interval = 1.6-31.6). There were no other significant differences by the multiple logistic regression analysis.

CONCLUSION

This study identified spinal fixation surgery that includes SIJF as a predictor for radiographic progression of hip OA over 12 months. We should pay attention to hip joint lesions after adult spinal deformity surgery, including SIJF.

The use of tranexamic acid in adult spinal deformity: is there an optimal dosing strategy?

BACKGROUND CONTEXT

ASD (Adult spinal deformity) surgery often entails complex osteotomies and realignment procedures, particularly in the setting of rigid deformities. Although previous studies have established the efficacy of tranexamic acid (TXA), data evaluating the widely variable dosing regimens remains sparse.

PURPOSE

To improve understanding of blood loss and transfusion requirements for low-dose and high-dose TXA regimens for adult spinal deformity (ASD) surgery.

STUDY DESIGN/SETTING

This is a retrospective cohort study of 318 ASD patients who received TXA. Outcome measures include estimated blood loss (EBL), perioperative transfusion requirement, and complications.

METHODS

A retrospective review was conducted on 318 ASD patients: 258 patients received a low-dose regimen of TXA (10 or 20 mg/kg loading dose with a 1 or 2 mg/kg/h maintenance dose) and 60 patients received a high-dose regimen of TXA (40 mg/kg loading dose with a 1 mg/kg/h maintenance dose, 30 mg/kg loading dose with a 10 mg/kg/h maintenance dose, or 50 mg/kg loading dose with a 5 mg/kg/h maintenance dose).

RESULTS

Compared with the low-dose TXA group, the high-dose TXA group had significantly decreased EBL (1402 vs. 1793 mL, p=.009), blood volume lost (30.3 vs. 39.4%, p=.01), intraoperative packed red blood cell (pRBC) transfusion (0.9 vs. 1.6 U, p<.0001), and intraoperative platelet transfusion (0 vs. 0.1 U, p<.0001). High-dose TXA was predictive of 515 cc less EBL (p=.002), 11.4% less blood volume lost (p=.004), and 1 U pRBC less transfused intraoperatively (p<.0001) than the low-dose TXA group. The high-dose TXA group had a higher incidence of postop atrial fibrillation (5 vs. 0%, p<.0001) and myocardial infarction (1.7 vs. 0%, p=.04).

CONCLUSIONS

Varying dosing regimens of TXA are utilized for ASD surgery, with a prevailing theme of dosing ambiguity. These data demonstrate that high-dose TXA is more effective than low-dose TXA in reducing blood loss and blood product transfusion requirement in ASD surgery. Importantly, rates of MI and postop AF were higher in the high-dose TXA group.

The Role of Potentially Modifiable Factors in a Standard Work Protocol to Decrease Complications in Adult Spinal Deformity Surgery: A Systematic Review, Part 1

STUDY DESIGN

Structured Literature Review.

OBJECTIVES

We sought to evaluate the peer-reviewed literature for potentially modifiable patient and surgical factors that could be incorporated into a Standard Work protocol to decrease complications in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Lean Methodology uses Standard Work to improve efficiency and decrease waste and error. ASD is known to have a high surgical complication rate. Several patient and surgical potentially modifiable factors have been suggested to affect complications, including preoperative hemoglobin, bone density, body mass index (BMI), age-appropriate realignment, preoperative albumin/prealbumin, and smoking status. We sought to evaluate the literature for evidence supporting these factors to include in a Standard Work protocol to decrease complications.

METHODS

Each of these six factors was developed into an appropriate clinical question that included the patient population, surgical intervention, a comparison group, and outcomes measure (PICO question). A comprehensive literature search was then performed. The authors reviewed abstracts and analyzed data from included studies. From 456 initial citations with abstract, 173 articles underwent full-text review. The best available evidence for clinical questions regarding the influence of these factors was provided by 93 included studies.

RESULTS

We found fair evidence supporting a low preoperative hemoglobin level associated with increased transfusion rates and decreased BMD and increased BMI associated with increased complication rates. Fair evidence supported low albumin/prealbumin associated with increased complications. There was fair evidence associating smoking exposure to increased reoperations, but conflicting evidence associating it with increased complications. There was no evidence in the literature evaluating age-appropriate realignment and complications.

CONCLUSION

Preoperative hemoglobin, bone density, body mass index, preoperative albumin/prealbumin, and smoking status all are potentially modifiable risk factors that are associated with increased complications in the adult spine surgery population. Developing a Standard Work Protocol for patient evaluation and optimization should include these factors.

LEVEL OF EVIDENCE

Level II.

The Role of Potentially Modifiable Factors in a Standard Work Protocol to Decrease Complications in Adult Spinal Deformity Surgery: A Systematic Review, Part 2

STUDY DESIGN

Structured literature review.

OBJECTIVES

To review the current literature for potentially modifiable patient and surgical factors that could be incorporated into a Standard Work protocol to decrease complications in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Application of lean methodology to health care involves standardization of work flow. Successful implementation of LEAN management can lead to dramatic reduction in variability and waste. Frailty, hemoglobin A1c (HbA1c) concentration, vitamin D level, mental health status, intraoperative fluid management (IFM), and tranexamic acid (TXA) administration may be modified to reduce complications after ASD surgery.

METHODS

Cochrane Central Register of Controlled Trials, MEDLINE/PubMed, Ovid, and Google Scholar databases were used to identify abstracts and citations for this review. Each topic was developed into an appropriate clinical question that included the patient population, surgical intervention, a comparison group, and outcomes measure (PICO question). From 373 initial citations with abstract, 134 articles underwent full-text review. The best available evidence for clinical questions regarding the influence of these factors was provided by 43 included studies.

RESULTS

We found fair evidence supporting an association between preoperative mental health disorders, frailty, vitamin D deficiency, and higher HbA1c levels and increased complications. Conversely, we found good evidence supporting an association between the use of intraoperative TXA and an optimized intraoperative fluid management and decreased complications.

CONCLUSION

Gaps in the existing literature limit our ability to evaluate if all of the patient and surgical factors selected for this review are associated with increased or decreased complications and reoperations in ASD surgery. However, for both intraoperative TXA usage and optimized intraoperative fluid management that were supported by good evidence, developing Standard Work Protocols may optimize care.

LEVEL OF EVIDENCE

Level II.

Use of Opioids and Other Analgesics Before and After Primary Surgery for Adult Spinal Deformity: A 10-Year Nationwide Study

Objective

To report the 1-year pre and postoperative analgesic use in patients undergoing primary surgery for adult spinal deformity (ASD) and assess risk factors for chronic postoperative opioid use.

Methods

Patients > 18 years undergoing primary instrumented surgery for ASD in Denmark between 2006 and 2016 were identified in the Danish National Patient Registry. Information on analgesic use were obtained from the Danish National Health Service Prescription Database. Use of analgesics was calculated one year before and after surgery for each patient, per quarter (-Q4 to -Q1 before and Q1 to Q4 after). Users were defined as patient with one or more prescriptions in the given quarter.

Results

We identified 892 patients. Preoperatively, 28% (n = 246) of patients were opioid users in -Q4 and 33% (n = 295) in -Q1. Postoperatively, 85% (n = 756) of patients were opioid users in Q1 and 31% (n = 280) in Q4. Proportions of users of other analgesics (paracetamol, antidepressants, and anticonvulsants) were stable before and after surgery. Use of nonsteroidal anti-inflammatory drug decreased postoperatively by 40% (-Q1 vs. Q4). 26% of patients had chronic preoperative opioid use (one or more prescriptions in each -Q2 and -Q1) and 24% had chronic postoperative use (prescription each of Q1–Q4). Multivariate logistic regression analysis showed age increment per 10 years and preoperative chronic opioid use as risk factors for chronic postoperative opioid use.

Conclusion

One year after ASD surgery, opioid use was not reduced compared to preoperative usage.

Rod stiffness as a risk factor of proximal junctional kyphosis after adult spinal deformity surgery: comparative study between cobalt chrome multiple-rod constructs and titanium alloy two-rod constructs

BACKGROUND CONTEXT

Little is known about the effect of rod stiffness as a risk factor of proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery.

PURPOSE

The aim of this study was to compare radiographic outcomes after the use of cobalt chrome multiple-rod constructs (CoCr MRCs) and titanium alloy two-rod constructs (Ti TRCs) for ASD surgery with a minimum 1-year follow-up.

STUDY DESIGN

Retrospective case-control study in two institutes.

PATIENT SAMPLE

We included 54 patients who underwent ASD surgery with fusion to the sacrum in two academic institutes between 2002 and 2015.

OUTCOME MEASURES

Radiographic outcomes were measured on the standing lateral radiographs before surgery, 1 month postoperatively, and at ultimate follow-up. The outcome measures were composed of pre- and postoperative sagittal vertical axis (SVA), pre- and postoperative lumbar lordosis (LL), pre- and postoperative thoracic kyphosis (TK)+LL+pelvic incidence (PI), pre- and postoperative PI minus LL, level of uppermost instrumented vertebra (UIV), evaluation of fusion after surgery, the presence of PJK, and the occurrence of rod fracture.

MATERIALS AND METHODS

We reviewed the medical records of 54 patients who underwent ASD surgery. Of these, 20 patients had CoCr MRC and 34 patients had Ti TRC. Baseline data and radiographic measurements were compared between the two groups. The Mann-Whitney U test, the chi-square test, and the Fisher exact test were used to compare outcomes between the groups.

RESULTS

The patients of the groups were similar in terms of age, gender, diagnosis, number of three-column osteotomy, levels fused, bone mineral density, preoperative TK, pre- and postoperative TK+LL+PI, SVA difference, LL change, pre- and postoperative PI minus LL, and location of UIV (upper or lower thoracic level). However, there were significant differences in the occurrence of PJK and rod breakage (PJK: CoCr MRC: 12 [60%] vs. Ti TRC: 9 [26.5%], p=.015; occurrence of rod breakage: CoCr MRC: 0 [0%] vs. Ti TRC: 11 [32.4%], p=.004). The time of PJK was less than 12 months after surgery in the CoCr MRC group. However, 55.5% (5/9) of PJK developed over 12 months after surgery in the Ti TRC group.

CONCLUSIONS

Increasing the rod stiffness by the use of cobalt chrome rod and can prevent rod breakage but adversely affects the occurrence and the time of PJK.

Measuring outcomes in adult spinal deformity surgery: a systematic review to identify current strengths, weaknesses and gaps in patient-reported outcome measures

PURPOSE

Adult spinal deformity (ASD) causes severe disability, reduces overall quality of life, and results in a substantial societal burden of disease. As healthcare is becoming more value based, and to facilitate global benchmarking, it is critical to identify and standardize patient-reported outcome measures (PROMs). This study aims to identify the current strengths, weaknesses, and gaps in PROMs used for ASD.

METHODS

Studies were included following a systematic search in multiple bibliographic databases between 2000 and 2015. PROMs were extracted and linked to the outcome domains of WHO's International Classification of Functioning and Health (ICF) framework. Subsequently, the clinimetric quality of identified PROMs was evaluated.

RESULTS

The literature search identified 144 papers that met the inclusion criteria, and nine frequently used PROMs were identified. These covered 29 ICF outcome domains, which could be grouped into three of the four main ICF chapters: body function (n = 7), activity and participation (n = 19), environmental factors (n = 3), and body structure (n = 0). A low quantity (n = 3) of papers was identified that studied the clinimetric quality of PROMs. The Scoliosis Research Society (SRS)-22 has the highest level of clinimetric quality for ASD.

CONCLUSIONS

Outcome domains related to mobility and pain were well represented. We identified a gap in current outcome measures regarding neurological and pulmonary function. In addition, no outcome domains were measured in the ICF chapter body structure. These results will serve as a foundation for the process of seeking international consensus on a standard set of outcome domains, accompanied PROMs and contributing factors to be used in future clinical trials and spine registries.