Perioperative and Delayed Major Complications Following Surgical Treatment of Adolescent Idiopathic Scoliosis

Perioperative Outcome of Severe Idiopathic Scoliosis (Cobb Angle ≥ 90°): Is There Any Difference Between "Daytime" Versus "After-hours" Surgeries?

STUDY DESIGN

Retrospective study from a prospectively collected database.

OBJECTIVE

To compare the perioperative outcome between after-hours and daytime surgery carried out by a dedicated spinal deformity team for severe Idiopathic Scoliosis (IS) patients with Cobb angle ≥ 90°.

SUMMARY OF BACKGROUND DATA

There were concerns that after-hours corrective surgeries in severe IS have higher morbidity compared to daytime surgeries.

METHODS

Seventy-one severe IS patients who underwent single-staged Posterior Spinal Fusion (PSF) were included. Surgeries performed between 08:00H and 16:59H were classified as "daytime" group and surgeries performed between 17:00H and 06:00H were classified as "after-hours" group. Perioperative outcome parameters were average operation start time and end time, operation duration, intraoperative blood loss, intraoperative hemodynamic parameters, preoperative and postoperative hemoglobin, blood transfusion rate, total patient-controlled anesthesia (PCA) morphine usage, length of postoperative hospitalization, and complications. Radiological variables assessed were preoperative and postoperative Cobb angle, side bending flexibility, number of fusion levels, number of screws used, Correction Rate, and Side Bending Correction Index.

RESULTS

Thirty patients were operated during daytime and 41 patients were operated after-hours. The mean age was 16.1 ± 5.8 years old. The mean operation start time for daytime group was 11:31 ± 2:45H versus 19:10 ± 1:24H for after-hours group. There were no significant differences between both groups in the operation duration, intraoperative blood loss, intraoperative hemodynamic parameters, postoperative hemoglobin, hemoglobin drift, transfusion rate, length of postoperative hospitalization, postoperative Cobb angle, Correction Rate, and Side Bending Correction Index. There were four complications (1 SSEP loss, 1 massive blood loss, and 2 superficial wound infections) with no difference between daytime and after-hours group.

CONCLUSION

After-hours elective spine deformity corrective surgeries in healthy ambulatory patients with severe IS performed by a dedicated spinal deformity team using dual attending surgeon strategy were as safe as those performed during daytime.

LEVEL OF EVIDENCE

4.

Surgical treatment of adolescent idiopathic scoliosis: Complications

Despite the fact that spinal surgeries for adolescent idiopathic scoliosis (AIS) result in good outcomes for most patients, they are not without complications either medically or surgically. Neurologic injury represents the most severe complication and is, as such, the most feared. Further complications include dural tears, peripheral neuropathy, surgical-site infections, implant-related issues, thromboembolic events, visual loss, pseudarthrosis, Crankshaft phenomenon, flatback phenomenon, proximal junctional kyphosis, and mortality. It is vital that all spine surgeons to be fully conversant with the possible complications and the proper responses for each of them.

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Surgeons should know how to manage complications of surgery for AIS.

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Patients should know about potential complications prior to surgery.

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Neurologic injury represents the most severe complication.

Spinal rod gripping capacity: how do 5.5/6.0-mm dual-diameter screws compare?

STUDY DESIGN

Biomechanical comparative study.

OBJECTIVE

To evaluate pedicle screw gripping capacity from five suppliers, comparing single-diameter (S-D) systems using 5.5-mm-diameter rods to dual-diameter (D-D) systems accepting 5.5- and 6.0-mm-diameter rods with both cobalt chromium (CoCr) and titanium alloy (Ti) rods. D-D systems have become increasingly prevalent; however, these systems theoretically may compromise spinal rod gripping, particularly when a smaller-diameter rod is used within a D-D pedicle screw.

METHODS

D-D pedicle screw systems from three suppliers (accepting 5.5- and 6.0-mm-diameter, Ti and CoCr rods), and S-D systems from two suppliers (accepting 5.5-mm-diameter, Ti and CoCr rods) were tested on an MTS MiniBionix machine. Axial load was applied in line with the rod to measure axial gripping capacity (AGC), and torsional load was applied to measure torsional gripping capacity (TGC) for each rod material and diameter. AGC and TGC were compared between D-D and S-D constructs, suppliers, rod diameters, and materials with subsequent classification and regression tree (CART) analysis.

RESULTS

5.5-mm rods within D-D screws were no weaker than 5.5-mm rods in S-D systems for AGC (dual > single, p = 0.043) and TGC (p = 0.066). As a whole, D-D systems had greater AGC than S-D systems (p = 0.01). AGC differed between suppliers (p < 0.001). No rod diameter (p = 0.227) or material (p = 0.131) effect emerged. With CART analysis, Supplier was the most significant predictor for greater AGC. As a whole, D-D systems had greater TGC than S-D systems (p = 0.008). TGC differed between suppliers (p < 0.001). Rod diameter was a significant predictor of higher TGC (6.0 > 5.5 mm, p = 0.002). CoCr rods had greater TGC than Ti (p < 0.001). CART analysis revealed that Supplier and CoCr material were significant predictors for increased TGC.

CONCLUSIONS

Despite 30%-70% variability in gripping capacity due to rod supplier and material, overall D-D pedicle screw systems had similar AGC and TGC as S-D systems.

LEVEL OF EVIDENCE

N/A.

Preoperative Pulmonary Function Test Results Are Not Associated With Postoperative Intubation in Children Undergoing Posterior Spinal Fusion for Scoliosis: A Retrospective Observational Study

BACKGROUND

Preoperative pulmonary function tests are routinely obtained in children with scoliosis undergoing posterior spinal fusion despite unclear benefits as a perioperative risk assessment tool and frequent inability of patients to provide acceptable results. The goal of this study was to determine whether preoperative pulmonary function test results are associated with the need for postoperative intubation or intensive care unit admission after posterior spinal fusion.

METHODS

The electronic medical records of patients who underwent posterior spinal fusion at a pediatric tertiary hospital between June 2012 and August 2017 were reviewed. Pulmonary function tests were consistently ordered for all patients, unless the patient was deemed unable to perform the test due to cognitive disability. Cases were categorized as primary or secondary scoliosis.Demographic data, preoperative bilevel positive airway pressure use, Cobb angle, intraoperative allogeneic blood transfusion, and ability to produce acceptable pulmonary function test results were collected for each patient. In patients with satisfactory pulmonary function test results, forced vital capacity and maximum inspiratory pressure were collected. Primary outcomes for analysis were postoperative intubation and intensive care unit admission. Univariable logistic regression models were used to assess the association between each variable of interest and the primary outcomes.

RESULTS

The study sample included 433 patients, 288 with primary scoliosis and 145 with secondary scoliosis. Among patients with primary scoliosis, 90% were able to produce acceptable pulmonary function test results, zero remained intubated postoperatively, and 6 were admitted to the intensive care unit. Among patients with secondary scoliosis, 44% could not attempt pulmonary function tests. Among those who did attempt the test, 30% were unable to produce meaningful results. Forced vital capacity and maximum inspiratory pressure were not found to be associated with postoperative intubation or intensive care unit admission. Weight, Cobb angle, intraoperative blood transfusion, American Society of Anesthesiologists physical status classification, and preoperative bilevel positive airway pressure use were associated with patient outcomes. Among 357 total patients who attempted pulmonary function tests, 37 had high-risk results. Only 1 of these 37 patients remained intubated postoperatively.

CONCLUSIONS

Patients undergoing posterior spinal fusion, especially those with secondary scoliosis, are frequently unable to adequately perform pulmonary function tests. Among patients with interpretable pulmonary function tests, there was no association between results and postoperative intubation or intensive care unit admission. Routine pulmonary function testing for all patients with scoliosis may not be indicated for purposes of risk assessment before posterior spinal fusion. Clinicians should consider a targeted approach and limit pulmonary function tests to patients for whom results may guide preoperative optimization as this may improve outcomes and reduce inefficiencies and costs.

Major complications following surgical correction of spine deformity in 257 patients with cerebral palsy

STUDY DESIGN

Observational.

OBJECTIVES

To report on the rate of major complications following spinal fusion and instrumentation to treat spinal deformity in patients with cerebral palsy (CP). Understanding the risk of major complications following the surgical treatment of spine deformities in patients with CP is critical.

METHODS

A prospectively collected, multicenter database of patients with CP who had surgical correction of their spinal deformity (scoliosis or kyphosis) was reviewed for all major complications. Patients with ≥ 2 year follow-up or who died ≤ 2 years of surgery were included. A complication was defined as major if it resulted in reoperation, re-admission to the hospital, prolongation of the hospital stay, was considered life-threatening, or resulted in residual disability. Overall complication and revision rates were calculated for the perioperative (Peri-op; occurring ≤ 90 days postoperative) and delayed postoperative (Delayed; > 90 days) time periods.

RESULTS

Two hundred and fifty-seven patients met inclusion. Seventy-eight (30%) patients had a major complication, 18 (7%) had > 1. There were 92 (36%) major complications; 64 (24.9%) occurred Peri-op. The most common Peri-op complications were wound (n = 16, 6.2%) and pulmonary issues (n = 28, 10.9%), specifically deep infections (n = 12, 4.7%) and prolonged ventilator support (n = 21, 8.2%). Delayed complications (n = 28, 10.9%) were primarily deep infections (n = 8, 3.1%) and instrumentation-related (n = 6, 2.3%). There were 42 additional surgeries for an overall unplanned return to the operating room rate of 16% (Peri-op: 8.6%, Delayed: 7.8%). Thirty-six (14.0%) reoperations were spine related surgeries (wound or instrumentation-related). Eleven (4.3%) patients died between 3 months to 5.6 years postoperatively; 4 occurred ≤ 1 year of surgery. Two deaths were directly related to the spinal deformity surgery.

CONCLUSION

Spinal deformity surgery in CP patients with greater than 2 years of follow-up have a postoperative major complication rate of 36% with a spine-related reoperation rate of 14.0%.

LEVEL OF EVIDENCE

Therapeutic-IV.

Long noncoding RNA lncAIS downregulation in mesenchymal stem cells is implicated in the pathogenesis of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex, three dimensional deformity of the spine that commonly occurs in pubescent girls. Abnormal osteogenic differentiation of mesenchymal stem cells (MSCs) is implicated in the pathogenesis of AIS. However, the biological roles of long noncoding RNAs (lncRNAs) in the regulation of osteogenic differentiation of MSCs are unknown. Through microarray analyses of bone marrow (BM) MSCs from healthy donors and AIS patients, we identified 1483 differentially expressed lncRNAs in AIS BM-MSCs. We defined a novel lncAIS (gene symbol: ENST00000453347) is dramatically downregulated in AIS BM-MSCs. In normal BM-MSCs, lncAIS interacts with NF90 to promote HOXD8 mRNA stability that enhances RUNX2 transcription in BM-MSCs, leading to osteogenic differentiation of normal BM-MSCs. By contrast, lncAIS downregualtion in AIS BM-MSCs cannot recruit NF90 and abrogates HOXD8 mRNA stability, which impedes RUNX2 transcription for osteogenic differentiation. Thereby lncAIS downregualtion in BM-MSCs suppresses osteogenic differentiation that is implicated in the pathogenesis of AIS.

Cervical Cord Injury Following Posterior Spinal Fusion in a Patient With Adolescent Idiopathic Scoliosis: A Case Report

CASE

We present an 11-year-old girl with adolescent idiopathic scoliosis who underwent uncomplicated posterior spinal fusion and developed transient upper extremity weakness secondary to a cervical cord injury several hours after the conclusion of the case.

CONCLUSIONS

Perioperative hypotension, positioning, and mild cervical canal stenosis contributed to cervical cord injury following posterior thoracic instrumentation. Optimal perioperative resuscitation and awareness of cervical spine anatomy along with proper positioning may prevent this rare but potentially serious complication.

Triggered EMG (T-EMG) Values of Pedicle Screws with a Powered Screwdriver vs A Standard Probe in Adolescent Idiopathic Scoliosis Do Not Agree: A Prospective Validation Study

Triggered electromyography (t-EMG) is a common technique used during spinal instrumentation in surgery for adolescent idiopathic scoliosis. This study tests the validity of t-EMG values obtained with a standard ball-tipped probe after completion of screw placement versus t-EMG values obtained during screw insertion with a powered screwdriver. t-EMG values were collected for screws spanning T7-L5 using both a standard probe and a powered screwdriver. A power analysis determined that a sample size of 300 screws would provide enough precision to estimate limits of agreement within ±2 mA. A monopolar constant current stimulation technique (0.2 ms duration and 3.11 Hz stimulation rate) was used at each level. EMG was acquired with placement of bipolar pairs of subdermal needle electrodes. A Bland-Altman plot was used to assess agreement between threshold readings from the two techniques. Twenty-nine patients were enrolled in this study with 305 screws. t-EMG values measured using a powered screwdriver were on average 1 mA lower than values from a standard probe. When readings less than or equal to 20 mA were considered, the limits of agreement were approximately 4 and 7 mA overall. In total, 28/305 (9%) screws were removed and reinserted, 9/305 (3%) screws were redirected, and 3/305 (1%) screws were aborted based on t-EMG readings. Despite a small overall difference in t-EMG value between the standard probe and screwdriver, there was still large variability in agreement between the two techniques. t-EMG values obtained with a powered screwdriver during screw insertion are not interchangeable with values measured by a probe.

Three-Dimensional Computed Tomography Analysis of Spinal Canal Length Increase After Surgery for Adolescent Idiopathic Scoliosis: A Multicenter Study

BACKGROUND

The most severe complication after surgery for adolescent idiopathic scoliosis is spinal cord injury. There is a relationship between corrective surgery and subsequent elongation of the spinal canal. We sought to investigate which factors are involved in this phenomenon.

METHODS

Seventy-seven patients with adolescent idiopathic scoliosis (49 with Lenke type 1 and 28 with type 2) who underwent spinal correction surgery were included. The mean patient age at surgery was 14.2 years (range, 11 to 20 years). The spines of all patients were fused within the range of T2 to L2, and computed tomography (CT) data were retrospectively collected. We measured the preoperative and postoperative lengths of the spinal canal from T2 to L2 using 3-dimensional (3D) CT-based imaging software. We also examined the association between the change in T2-L2 spinal canal length and the radiographic parameters.

RESULTS

The length of the spinal canal from T2 to L2 was increased by a mean of 8.5 mm in the patients with Lenke type 1, 12.7 mm in those with type 2, and 10.1 mm overall. Elongation was positively associated with the preoperative main thoracic Cobb angle in both the type-1 group (R = 0.43, p < 0.005) and the type-2 group (R = 0.77, p < 0.000001). The greatest elongation was observed in the periapical vertebral levels of the main thoracic curves.

CONCLUSIONS

Corrective surgery for adolescent idiopathic scoliosis elongated the spinal canal. The preoperative proximal, main thoracic, and thoracolumbar/lumbar Cobb angles are moderate predictors of postoperative spinal canal length after scoliosis surgery.

CLINICAL RELEVANCE

It is important to understand how much the spinal canal is elongated after surgery to lessen the risk of intraoperative and postoperative neurological complications.

Major Complications at Two Years After Surgery Impact SRS Scores for Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To determine whether adolescent idiopathic scoliosis (AIS) patients with active complications at two-year follow-up demonstrate lower Scoliosis Research Society (SRS-22) questionnaire scores.

SUMMARY OF BACKGROUND DATA

There is limited evidence as to whether the SRS-22 is sensitive to complications in postoperative AIS patients.

METHODS

Surgical patients with SRS-22 scores completed at two-year follow-up were included. Five groups were created: no complication, minor complication resolved by 2 years, major complication resolved by 2 years, minor complication active, and major complication active at 2 years. Likelihood of reaching a minimal clinically important difference (MCID) for pain (0.20) and self-image (0.98) was evaluated.

RESULTS

1,481 patients were identified. Major complications active at two years existed in 2.2% of patients. These patients had the lowest score in all domains and total scores (p < .05). If a minor complication was active, scores were impacted for pain, self-image, satisfaction, and total (p < .05). No differences were found between no complication and resolved complications. Patients with active major complications were more likely to have a pain score that worsened from pre- to two years reaching MCID (52%) compared to the other four groups (range 18%-29%, odds ratio [OR] 3.6, p < .001). They also had a nonsignificant decreased rate of improvement of self-image score at an MCID level (42% vs. range 51%-66%, OR 0.56, p = .10).

CONCLUSIONS

When timing is considered, the SRS-22 demonstrates the ability to discriminate between patients with and without a complication. Active experience of a major complication impacted SRS-22 scores, in particular, the rate of worsening scores for pain, self-image, function, and total score.

LEVEL OF EVIDENCE

Level III.

Perioperative Complications After Spinal Fusion in Pediatric Patients With Congenital Heart Disease

BACKGROUND

Children with congenital heart disease (CHD) have been reported to be at increased risk of developing scoliosis following cardiac surgery. Previous sample studies have reported that these patients may safely undergo posterior spinal fusion (PSF) with low complication rates. The goal of this study is to provide an updated analysis of the perioperative complication profile for posterior spinal fusion in a large cohort of pediatric patients with CHD, using a nationwide database.

METHODS

A retrospective cohort study was conducted using 30-day perioperative outcomes data from the NSQIP-P database. Our inclusion criteria were all pediatric patients who underwent posterior spinal fusion by CPT code. Patients were subdivided into two groups: those with a history of cardiac surgery for CHD and those without. Postoperative complications were classified according to the Clavien-Dindo system. Risk factors were assessed in univariate and multivariate logistic regression analyses, with significance set at p < .05.

RESULTS

Our results included 3,426 pediatric patients (68.2% female, 31.8% male) with a median age at spinal fusion of 13.7 ± 2.87 years. A CHD diagnosis was present in 312 patients, with 128 having had prior cardiac surgery. The overall complication rate was 6.68%, with a 10.9% rate in the prior cardiac surgery cohort (p = .068). The most common overall perioperative complications were unplanned readmission (3.5%), reoperation (2.6%), and superficial wound dehiscence (2.5%). Patients with a history of cardiac surgery were not at increased risk for postoperative complications; however, blood transfusion (p < .001), bronchopulmonary dysplasia (p < .001), combined bronchopulmonary dysplasia and previous cardiac surgery (p = .004), and a neuromuscular diagnosis (p < .001) were all risk factors for major postoperative complications in this cohort.

CONCLUSIONS

Children with scoliosis who have undergone cardiac surgery to address CHD are not at an increased risk of perioperative complications within 30 days of undergoing a posterior spinal fusion. However, patients who underwent cardiac surgery for CHD who also had bronchopulmonary dysplasia or an associated neuromuscular diagnosis are at increased risk for perioperative complications. It is important for pediatric orthopedic spine surgeons to be familiar with an updated profile of potential perioperative obstacles they may face when treating these patients, as seen in a large and representative cohort.

LEVEL OF EVIDENCE

Level III.

Should all paediatric patients with presumed idiopathic scoliosis undergo MRI screening for neuro-axial disease?

BACKGROUND

Idiopathic scoliosis is a relatively common childhood condition affecting 0.47-5.2% of the population. Traditional interventions focus on orthopaedic correction of the curve angle. There is a spectrum of patients with scoliosis who are found to have neuro-axial abnormality on full MRI of the spine, but not all surgeons request imaging in the absence of neurological symptoms. There is evidence to suggest that treatment of neuro-axial disease may improve scoliosis curve outcome. We therefore sought to estimate what proportion of patients with normal neurology and scoliosis are found to have neuro-axial abnormality on full MRI imaging of the spine, in particular Chiari malformation and syringomyelia.

RESULTS

Out of 11 identified studies consisting of 3372 paediatric patients (age < 18 years), mean weighted proportion demonstrates that 14.7% of patients with scoliosis (Cobb angle > 20°) and normal neurological examination will demonstrate a neuro-axial abnormality on full MRI imaging of the spine. Of patients, 8.3 and 8.4% were found to have Chiari malformation and syringomyelia, respectively.

CONCLUSIONS

Up to one in seven paediatric patients with scoliosis and normal neurological examination will demonstrate neuro-axial disease on MRI imaging of the spine. Given that younger age and earlier age of decompression is associated with improvement in curve angle, it seems important that MRI screening be considered in all patients regardless of neurological examination findings. There is a potentially long-term benefit in these patients. Multi-cross institutional prospective studies are encouraged to further investigate effect on curve angle.