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Journal of Craniovertebral Junction & Spine logoLink to Journal of Craniovertebral Junction & Spine
. 2023 Jun 13;14(2):165–174. doi: 10.4103/jcvjs.jcvjs_28_23

Navigated versus conventional pediatric spinal deformity surgery: Navigation independently predicts reoperation and infectious complications

Austen D Katz 1, Junho Song 1,, Sayyida Hasan 1, Jesse M Galina 1, Sohrab Virk 1, Jeff Scott Silber 1, David Essig 1, Vishal Sarwahi 1
PMCID: PMC10336894  PMID: 37448507

Abstract

Context:

Literature on treating pediatric spinal deformity with navigation is limited, particularly using large nationally represented cohorts. Further, the comparison of single-institution data to national-level database outcomes is also lacking.

Aim:

(1) To compare navigated versus conventional posterior pediatric deformity surgery based on 30-day outcomes and perioperative factors using the National Surgical Quality Improvement Program (NSQIP) database and (2) to compare the outcomes of the NSQIP navigated group to those of fluoroscopy-only and navigated cases from a single-institution.

Settings and Design:

Retrospective cohort study.

Subjects and Methods:

Pediatric patients who underwent posterior deformity surgery with and without navigation were included. Primary outcomes were 30-day readmission, reoperation, morbidity, and complications. The second part of this study included AIS patients < 18 years old at a single institution between 2015 and 2019. Operative time, length of stay, transfusion rate, and complication rate were compared between single-institution and NSQIP groups.

Statistical Analysis Used:

Univariate analyses with independent t-test and Chi-square or Fisher's exact test was used. Multivariate analyses through the application of binary logistic regression models.

Results:

Part I of the study included 16,950 patients, with navigation utilized in 356 patients (2.1%). In multivariate analysis, navigation predicted reoperation, deep wound infection, and sepsis. After controlling for operative year, navigation no longer predicted reoperation. In Part II of the study, 288 single institution AIS patients were matched to 326 navigation patients from the NSQIP database. Operative time and transfusion rate were significantly higher for the NSQIP group.

Conclusions:

On a national scale, navigation predicted increased odds of reoperation and infectious-related events and yielded greater median relative value units (RVUs) per case but had longer operating room (OR) time and fewer RVUs-per-minute. After controlling for operative year, RVUs-per-minute and reoperation rates were similar between groups. The NSQIP navigated surgery group was associated with significantly higher operative time and transfusion rates compared to the single-institution groups.

Keywords: Adolescent idiopathic scoliosis, complications, navigation, pediatric spinal deformity, reoperation

INTRODUCTION

The frequency of spinal deformity surgery has been increasing due to technological advancements.[1,2,3,4,5] The intricate complexities of spinal anatomy, particularly in deformity surgery, have led to the development of new techniques designed to minimize adverse events.[2,3,6,7,8] Navigation has been developed to maximize pedicle screw placement accuracy and has been of particular benefit in complex spinal deformity cases, with the goal of minimizing complications and hardware failure and reducing blood loss.[2,9,10,11]

While current research has demonstrated positive clinical satisfaction and radiographic accuracy with the use of navigation for treating degenerative disease, literature on treating pediatric deformity with navigation is limited, particularly using large nationally represented cohorts.[11,12] Further, comparison of single-institution data to national-level database outcomes is also limited. Such comparison could provide insight into learning curves and technique-related factors associated with better outcomes.

The purpose of this study was to compare navigated versus conventional posterior pediatric deformity surgery based on 30-day readmission, reoperation, and morbidity and perioperative factors using the NSQIP database and to compare the outcomes of the NSQIP navigated group to those of fluoroscopy-only and navigated cases from a single-institution.

SUBJECTS AND METHODS

Study design and population

This two-part study consists of a retrospective analysis of data from the Pediatric American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database and a comparison to patients from a single institution who were operated on by the senior author. The first part of the project is exempt from Institutional Review Board (IRB) review and informed consent requirement as it utilized a de-identified, publicly available database, and no direct patient involvement occurred. For the second part of the study, IRB approval was obtained at the senior author's home institution (Feinstein Institute for Medical Research at Northwell Health, IRB #21-0165).

Part I

The NSQIP database began in 1994 as an initiative to improve the quality of surgical care in the Veterans Administration and later expanded to all participating hospitals in the United States. At present, there are over 680 participating hospitals with standardized clinical reviewers and routine site audits to ensure the reliable data. The database has frequently been used in the spine literature.[13,14]

Pediatric patients who underwent posterior deformity surgery were identified in the 2012–2018 NSQIP databases using Current Procedural Terminology (CPT) codes 22800-22804. Patients were stratified into groups with and without navigation using CPT code 61873. Patients were excluded if they had preoperative infection, open wound, cerebral hemorrhage, wound class >1, required Cardiopulmonary Resuscitation (CPR), transfusion, or inotropic support prior to surgery, or underwent surgery for revision, lesion, or nonelective or urgent purposes. Patients with missing 30-day outcomes were also excluded. Patients were also excluded if they had anterior fusion, nonelective, or lesion-related CPT codes.

Part II

The second part of this study consisted of an IRB-approved retrospective chart review of AIS patients, <18 years old, at a single institution between 2015 and 2019. Patients were excluded if they had <2 years of follow-up or had undergone previous spine surgery or surgery for a non-idiopathic etiology. The single-institution patients were divided into fluoroscopy (Fluoro) and “technique'n'technology” (TNT) groups and were compared to each other and to the navigated AIS patients from the NSQIP dataset (NAV). All pedicle screws were introduced by senior surgeons through freehand anatomic technique: Screws were placed based on anatomic landmarks, with ball-tipped probes used to palpate the screw tracts. In the Fluoro group, once placed, screw positioning was verified under fluoroscopy before rod placement. Patients operated on between 2015 and 2017 were placed in the Fluoro group. In the TNT group, once screws were placed using the freehand anatomic technique, Airo computed tomography (CT) scan navigation was utilized in lieu of fluoroscopy, whereby a reference clamp was attached to one of the spinous processes in the area of the arthrodesis based on surgeon preference. After clamp positioning, a radiology technician executed the CT scans with the mobile scanner and images were automatically transferred to the workstation. Screw positioning was once again verified before rod placement with no additional image guidance or navigation thereafter. Patients operated on between 2018 and 2019 were placed in the TNT group.

In 2018, the Airo CT scanner (Brainlab AG) was introduced at our institution for spine-related surgeries. The scanner consists of a CT table and image-guidance system that allows for real-time CT navigation. Surgeons conducted Airo procedures using the “TNT” approach.

Outcomes and statistical analyses

Part I

Primary outcomes were 30-day readmission, reoperation, overall morbidity, and specific complications. Readmission includes any inpatient stay to the same or another hospital related to the surgical procedure. Reoperation includes all major surgical procedures requiring return to the operating room for intervention of any kind. Morbidity includes infectious, pulmonary, cardiac, renal, neurological, hematologic, and thromboembolic complications reported in the ACS-NSQIP dataset. In addition, reasons for reoperation were obtained from NSQIP-provided data and were compared between navigated and conventional groups.

Primary outcomes, as well as specific complications, were compared between navigated and conventional groups. Predictors of primary outcomes were analyzed for among the entire cohort. The variables evaluated as potential predictors included patient demographic, comorbidity, laboratory values, and procedural factors [Table 1]. Procedural factors specifically included operative time, length of hospital stay, and relative value units (RVUs) per case and per minute of operative time. The specific complications are provided in Table 2.

Table 1.

Baseline differences in patient demographic, comorbidity, laboratory, and procedural factors, and primary outcomes by presence or absence of computer-assisted surgery

With CAS (n=356) Without CAS (n=16,594) P Cases available (n=16,950)
Demographics, n (%)
 Age (years), mean (SD) 13.8 (2.8) 13.8 (2.7) 0.866 16,950
 African−American race 39 (11.8) 2696 (18.2) 0.003 15,120
 Hispanic ethnicity 31 (8.8) 1625 (10.6) 0.292 15,712
 Female gender 245 (68.8) 11,575 (69.8) 0.704 16,950
Comorbidities, n (%)
 Obese 56 (16.3) 2416 (15.3) 0.619 16,132
 Pulmonary comorbidity 69 (19.4) 2795 (16.8) 0.206 16,950
 Cardiac comorbidity 26 (7.3) 1453 (8.8) 0.337 16,950
 Esophageal/GI disease 33 (9.3) 1692 (10.2) 0.567 16,950
 Developmental delay 79 (22.2) 3505 (21.1) 0.625 16,950
 Seizure disorder 31 (8.7) 1580 (9.5) 0.605 16,950
 Cerebral palsy 30 (8.4) 1571 (9.5) 0.507 16,950
 Structural CNS abnormality 49 (13.8) 2202 (13.3) 0.786 16,950
 Neuromuscular disorder 72 (20.2) 3668 (22.1) 0.397 16,950
 Preoperative steroid use 3 (0.8) 179 (1.1) 1.000# 16,950
 Nutritional support 26 (7.3) 1274 (7.7) 0.793 16,950
 Hematologic disorder 10 (2.8) 309 (1.9) 0.193 16,950
 Congenital malformation 86 (24.2) 5077 (30.6) 0.009 16,950
 Childhood malignancy 5 (1.4) 166 (1.0) 0.450 16,950
 ASA-class ≥3 108 (30.4) 5055 (30.5) 0.977 16,932
Lab values, mean (SD)
 White cell count 7.0 (2.3) 6.9 (2.3) 0.758 14,089
 Hematocrit 40.5 (3.6) 39.9 (3.4) 0.005 14,481
 INR 1.1 (0.1) 1.1 (0.1) 0.672 9657
Procedural factors, median (IQR)
 Operative time (min) 331 (248–435) 269 (205–344) <0.001 16,940
 LOS (days) 4 (3–5) 4 (3–5) 0.304 16,909
 Total RVUs 57.7 (49.3–77.4) 53.9 (45.6–74.4) <0.001 16,950
 RVUs per minute 0.18 (0.13–0.26) 0.21 (0.15–0.28) <0.001 16,940
 Total RVUs subtracting NAV 50.9 (42.5–70.6) 53.9 (45.6–74.4) 0.238 16,948
Unadjusted primary outcomes, n (%)
 Readmission 21 (5.9) 647 (3.9) 0.055 16,950
 Reoperation 22 (6.2) 513 (3.1) 0.001 16,950
 Mean days to reoperation 16.3 (7.4) 14.1 (8.4) 0.229
 Morbidity 269 (75.6) 11,199 (67.5) 0.001 16,950

#Fisher’s exact test. Bold values indicate significance (P<0.05). Pulmonary comorbidities include ventilator dependence, asthma, chronic lung disease, chronic oxygen support, tracheostomy, or structural pulmonary or airway abnormalities. Cardiac comorbidities include previous cardiac surgery and cardiac risk factors. IQR - Interquartile ranges; ASA - American Society of Anesthesiologists; RVUs - Relative value units; CAS – Computer-assisted surgery; GI - Gastric/intestinal; CNS - Central nervous system; SD - Standard deviation; LOS - Length of stay; INR - International normalized ratio; NAV - Navigated patients from the NSQIP dataset

Table 2.

Univariate and multivariate analysis of specific complication by presence or absence of computer assisted surgery

Specific complication With CAS, n (%) Without CAS, n (%) Univariate P OR (95% CI) Multivariate P
Any wound complication 21 (5.9) 677 (4.1) 0.087
 Superficial site infection 4 (1.1) 124 (0.7) 0.417#
 Deep wound infection 9 (2.5) 134 (0.8) 0.003# 2.926 (1.305–6.563) 0.009
 Organ space infection 1 (0.3) 39 (0.2) 0.573#
 Wound dehiscence 10 (2.8) 499 (3.0) 0.828
Pulmonary complication 4 (1.1) 269 (1.6) 0.461
 Pneumonia 3 (0.8) 178 (1.1) 1.000#
 Unplanned intubation 1 (0.3) 134 (0.8) 0.536#
 Pulmonary embolism 0 4 (0.02) 1.000#
Acute kidney injury 1 (0.3) 17 (0.1) 0.318#
Urinary tract infection 3 (0.8) 122 (0.7) 0.748#
Stroke/CVA 0 5 (0.03) 1.000#
Seizure 0 10 (0.1) 1.000#
Nerve injury 0 58 (0.3) 0.636#
Cardiac arrest requiring CPR 1 (0.3) 23 (0.1) 0.399#
Transfusion 262 (73.6) 10,938 (65.9) 0.002 0.977 (0.731–1.306) 0.874
Blood stream infection 0 5 (0.03) 1.000#
Sepsis/septic shock 8 (2.2) 124 (0.7) 0.007# 3.192 (1.324–7.693) 0.010

#Fisher’s exact test. Bold values indicate significance (P<0.05). CPR - Cardiopulmonary resuscitation; CVA - Cerebrovascular accident; CAS – Computer-assisted surgery; OR - Odds ratio; CI - Confidence interval

Demographic, comorbidity, laboratory, and procedural factors were individually analyzed for the baseline differences between navigated and conventional patients using Student's t-test for continuous and Chi-squared or Fisher's exact test for the categorical variables. The above factors were also individually analyzed for association with primary outcomes using univariate logistic regression. Variables significant in the univariate analyses (P < 0.05) were then evaluated for significance (P < 0.05) as independent predictors and control variables in a series of multivariate logistic regression analyses of primary outcomes.

In addition, post hoc analyses controlling for operative year were performed for primary outcomes using multivariate logistic regression and for operative time, RVUs per case, and RVUs per minute, with multivariate analysis performed using quantile (median) regression.

Part II

The fluoro, TNT, and NAV were compared on the basis of operative time, length of stay, transfusion rate, and complication rate. In addition, the Fluoro and TNT groups were compared to each other on the basis of total radiation time and dose, preoperative and postoperative Cobb angle, correction of Cobb, preoperative and postoperative kyphosis, operative time, estimated blood loss, and length of stay.

Shapiro–Wilk test was used to confirm the distribution normality. Data were presented as medians and interquartile (25th–75th percentile) ranges in the continuous variables (Cobb, kyphosis, etc.) and frequency and percentages for the categorical variables (complication, transfusion, etc.). The continuous data were analyzed using Kruskal–Wallis or Wilcoxon rank-sum test and categorical data were analyzed using the Chi-square and Fisher's exact test. Statistical analyses were performed by an independent biostatistician with SAS version 9.3 (SAS Institute, Cary NC). All P values were two tailed, with P < 0.05 considered significant.

RESULTS

Part I

There were 16,950 patients included, with navigation utilized in 356 patients (2.1%). Significant baseline differences were only observed in only 3 of 22 demographic and comorbidity variables [Table 1]. Patients in the navigated group were significantly less likely to be African − American (11.8 vs. 18.2%, P = 0.003) or to have a congenital malformation (24.2 vs. 30.6%, P = 0.009), and had greater mean preoperative hematocrit (40.5 vs. 39.9, P = 0.005), compared to those in the conventional group, respectively.

Navigation was associated with longer median operative times (331 vs. 269 min) and total median RVUs per case (57.7 vs. 53.9), but fewer median RVUs per minute (0.18 vs. 0.21) compared to conventional surgery, respectively (P < 0.001). There was no difference in total median RVUs per case when subtracting the value of RVUs for navigation, 6.81, from the navigated cases (50.9 vs. 53.9, P = 0.238). The median length of stay was similar between groups (4 vs. 4 days, P = 0.304).

In univariate analysis [Tables 1 and 2], navigation was associated with greater rates of reoperation (6.2 vs. 3.1%, P = 0.001) and overall morbidity (75.6 vs. 67.5%, P = 0.001). Navigation was also associated with the greater rates of wound infection (2.5 vs. 0.8%, P = 0.003), transfusion (73.6 vs. 65.9%, P = 0.002), and sepsis/septic shock (2.2 vs. 0.7%, P = 0.007). Readmission rates (5.9 vs. 3.9%, P = 0.055) and mean duration from surgery to reoperation (16.3 vs. 14.1 days, P = 0.229) were similar between groups.

After adjusting for significant baseline differences and predictor variables in multivariate analysis [Tables 2-5], navigation predicted reoperation (odds ratio [OR] = 1.920, P = 0.019, 95% confidence interval [CI95]: 1.115–3.306), deep wound infection (OR = 2.926, P = 0.009, CI95: 1.305–6.563), and sepsis/septic shock (OR = 3.192, P = 0.010, CI95: 1.324–7.693), but no longer predicted overall morbidity (P = 0.955) or transfusion (P = 0.874). Reoperation most commonly occurred due to site-related complications followed by hardware-related events [Figure 1].

Table 5.

Univariate and multivariate analysis of predictors of morbidity

Univariate Multivariate


Morbidity (n=5482) No morbidity (n=16,282) P OR (95% CI) P
Demographics, n (%)
 Age (years), mean (SD) 13.9 (2.5) 13.5 (3.1) <0.001 1.051 (1.034–1.069) <0.001
 African−American race 1966 (19.1) 769 (16.0) <0.001 1.193 (1.068–1.333) 0.002
 Hispanic ethnicity 1180 (11.0) 476 (9.6) 0.008 1.401 (1.206–1.628) <0.001
 Female gender 7826 (68.2) 3994 (72.9) <0.001 0.959 (0.870–1.058) 0.403
Comorbidities, n (%)
 Obese 1638 (15.1) 834 (15.8) 0.264
 Pulmonary comorbidity 2132 (18.6) 732 (13.4) <0.001 1.032 (0.906–1.177) 0.634
 Cardiac comorbidity 1066 (9.3) 413 (7.5) <0.001 1.113 (0.950–1.305) 0.184
 Esophageal/GI disease 1366 (11.9) 359 (6.5) <0.001 1.247 (1.045–1.487) 0.014
 Developmental delay 2794 (24.4) 790 (14.4) <0.001 1.291 (1.113–1.498) 0.001
 Seizure disorder 1343 (11.7) 268 (4.9) <0.001 1.384 (1.111–1.723) 0.004
 Cerebral palsy 1338 (11.7) 263 (4.8) <0.001 1.078 (0.859–1.353) 0.519
 Structural CNS abnormality 1621 (14.1) 630 (11.5) <0.001 0.798 (0.695–0.917) 0.001
 Neuromuscular disorder 2894 (25.2) 846 (15.4) <0.001 1.310 (1.150–1.492) <0.001
 Preoperative steroid use 141 (1.2) 41 (0.7) 0.004 1.294 (0.829–2.020) 0.256
 Nutritional support 1088 (9.5) 212 (3.9) <0.001 1.218 (0.958–1.548) 0.107
 Hematologic disorder 249 (2.2) 70 (1.3) <0.001 1.233 (0.885–1.718) 0.216
 Congenital malformation 3610 (31.5) 1553 (28.3) <0.001 0.863 (0.779–0.956) 0.005
 Childhood malignancy 100 (0.9) 71 (1.3) 0.010 0.579 (0.392–0.855) 0.006
 ASA-class ≥3 3847 (33.6) 1316 (24.0) <0.001 0.904 (0.800–1.022) 0.106
Lab values, mean (SD)
 White cell count 6.9 (2.4) 6.9 (2.2) 0.423 0.993 (0.975–1.011) 0.442
 Hematocrit 39.9 (4.4) 39.9 (4.4) 0.987 0.979 (0.968–0.991) 0.001
 INR 1.1 (0.1) 1.1 (0.1) 0.228
Procedural factors
 Computer assistance
  With CAS 269 (75.6a) 87 0.001 0.992 (0.738–1.333) 0.955
  Without CAS 11,199 (67.5b) 15,947
 Operative time 304 (111) 247 (94) <0.001 1.005 (1.005–1.006) <0.001
 LOS 5.6 (5.8) 4.9 (5.7) <0.001 0.999 (0.991–1.007) 0.776
 Total RVUs 62.9 (27.4) 54.7 (24.0) <0.001 1.009 (1.007–1.011) <0.001

aPercent of patients with CAS who experienced morbidity; bPercent of patients without CAS who experienced morbidity; #Fisher’s exact test. Bold values indicate significance (P<0.05). Pulmonary comorbidities include ventilator dependence, asthma, chronic lung disease, chronic oxygen support, tracheostomy, or structural pulmonary or airway abnormalities. Cardiac comorbidities include previous cardiac surgery and cardiac risk factors. ASA - American Society of Anesthesiologists; RVUs - Relative value units; CAS - Computer assisted surgery; GI - Gastric/intestinal; CNS - Central nervous system; SD - Standard deviation; INR - International normalized ratio; OR - Odds ratio; CI - Confidence interval; LOS - Length of stay

Figure 1.

Figure 1

Reasons for reoperations among navigated and conventional pediatric spinal deformity fusion patients

Table 4.

Univariate and multivariate analysis of predictors of reoperation

Univariate Multivariate


Reoperation (n=535) No reoperation (n=16,415) P OR (95% CI) P
Demographics, n (%)
 Age (years), mean (SD) 13.4 (3.1) 13.8 (2.7) 0.002 1.012 (0.970–1.056) 0.586
 African−American race 88 (18.3) 2647 (18.1) 0.922 1.083 (0.813–1.444) 0.585
 Hispanic ethnicity 53 (10.6) 1603 (10.5) 0.989
 Female gender 325 (60.7) 11,495 (70.0) <0.001 0.947 (0.745–1.203) 0.947
Comorbidities, n (%)
 Obese 131 (26.7) 2341 (15.0) <0.001 2.472 (1.901–3.214) <0.001
 Pulmonary comorbidity 175 (32.7) 2689 (16.4) <0.001 1.216 (0.922–1.604) 0.166
 Cardiac comorbidity 77 (14.4) 1402 (8.5) <0.001 1.067 (0.764–1.490) 0.704
 Esophageal/GI disease 119 (22.2) 1606 (9.8) <0.001 0.847 (0.608–1.179) 0.326
 Developmental delay 260 (48.6) 3324 (20.2) <0.001 1.926 (1.414–2.622) <0.001
 Seizure disorder 132 (24.7) 1479 (9.0) <0.001 1.230 (0.861–1.758) 0.255
 Cerebral palsy 125 (23.4) 1476 (9.0) <0.001 1.064 (0.739–1.534) 0.738
 Structural CNS abnormality 138 (25.8) 2180 (12.9) <0.001 1.171 (0.883–1.554) 0.273
 Neuromuscular disorder 244 (45.6) 3496 (21.3) <0.001 1.533 (1.162–2.021) 0.002
 Preoperative steroid use 13 (2.4) 169 (1.0) 0.002 1.056 (0.491–2.271) 0.889
 Nutritional support 106 (19.8) 1194 (7.3) <0.001 0.867 (0.588–1.277) 0.470
 Hematologic disorder 23 (4.3) 296 (1.8) <0.001 0.913 (0.487–1.711) 0.777
 Congenital malformation 272 (50.8) 4,891 (29.8) <0.001 1.091 (0.846–1.406) 0.502
 Childhood malignancy 4 (0.7) 167 (1.0) 0.539
 ASA-class ≥3 321 (60.0) 4842 (29.5) <0.001 1.519 (1.123–2.055) 0.007
Lab values, mean (SD)
 White cell count 7.4 (2.7) 6.9 (2.3) <0.001 1.024 (0.981–1.069) 0.284
 Hematocrit 39.8 (4.3) 39.9 (3.8) 0.551 0.982 (0.954–1.010) 0.195
 INR 1.1 (0.1) 1.1 (0.1) 0.882
Procedural factors
 Computer assistance, n (%)
  With CAS 22 (6.2a) 334 0.001 1.920 (1.115–3.306) 0.019
  Without CAS 513 (3.1b) 16,081
 Operative time 333 (122) 284 (108) <0.001 1.002 (1.001–1.003) <0.001
 LOS 10.7 (12.7) 5.2 (5.3) <0.001 1.040 (1.031–1.050) <0.001
 Total RVUs 67.8 (29.4) 60.0 (26.5) <0.001 1.005 (1.001–1.003) 0.010

aPercent of patients with CAS who returned to the operating room; bPercent of patients without CAS who returned to the operating room; #Fisher’s exact test. Bold values indicate significance (P<0.05). Pulmonary comorbidities include ventilator dependence, asthma, chronic lung disease, chronic oxygen support, tracheostomy, or structural pulmonary or airway abnormalities. Cardiac comorbidities include previous cardiac surgery and cardiac risk factors. ASA - American Society of Anesthesiologists; RVUs - Relative value unit; CAS - Computer-assisted surgery; GI - Gastric/intestinal; CNS - Central nervous system; SD - Standard deviation; OR - Odds ratio; CI - Confidence interval; LOS - Length of stay; INR - International normalized ratio

Post hoc multivariate logistic regression analysis demonstrated that, after controlling for operative year, navigation no longer predicted reoperation (OR = 1.005, P = 0.058, CI95: 1.068–1.230). Multivariate quantile regression revealed that, while navigation predicted a 44-min increase (P < 0.001, CI95: 29–60 min) in median operative time, it also predicted an 8.2 unit increase in median RVUs per case (P < 0.001, CI95: 5.7–10.7 RVUs), yielding a statistically insignificant 0.008 unit decrease in median RVUs per minute (P = 0.293, CI95: −0.022–0.007) compared to conventional surgery.

Medical comorbidities predictive of poorer 30-day outcomes are provided in Tables 3-5. Of note, female gender was protective of readmission (OR = 0.787, P = 0.021), while obesity (OR = 2.010, P < 0.001), pulmonary comorbidity (OR = 1.463, P = 0.001), and developmental delay (OR = 1.637, P < 0.001) predicted readmission. Obesity (OR = 2.472, P < 0.001), developmental delay (OR = 1.926, P < 0.001), operative time (OR = 1.002, P < 0.001), length of stay (OR = 1.040, P < 0.001), and total RVUs (OR = 1.005, P = 0.010) predicted reoperation. Finally, age (OR = 1.051, P < 0.001), African − American race (OR = 1.193, P = 0.002), Hispanic ethnicity (OR = 1.401, P < 0.001), developmental delay (OR = 1.291, P < 0.001), seizure disorder (OR = 1.384, P = 0.004), neuromuscular disorder (OR = 1.310, P < 0.001), operative time (OR = 1.005, P < 0.001), and total RVUs (OR = 1.009, P < 0.001) predicted morbidity.

Table 3.

Univariate and multivariate analysis of predictors of readmission

Univariate Multivariate


Readmitted (n=668), n (%) Not readmitted (n=16,282), n (%) P OR (95% CI) P
Demographics, n (%)
 Age (years), mean (SD) 13.4 (3.2) 13.8 (2.7) 0.001 0.998 (0.963–1.034) 0.902
 African−American race 109 (18.0) 2626 (18.1) 0.947 1.144 (0.895–1.463) 0.281
 Hispanic ethnicity 76 (12.0) 1580 (10.5) 0.209
 Female gender 377 (56.4) 11,443 (70.3) <0.001 0.787 (0.642–0.964) 0.021
Comorbidities, n (%)
 Obese 139 (22.4) 2333 (15.0) <0.001 2.010 (1.588–2.544) <0.001
 Pulmonary comorbidity 234 (35.0) 2630 (16.2) <0.001 1.463 (1.157–1.850) 0.001
 Cardiac comorbidity 91 (13.6) 1388 (8.5) <0.001 1.006 (0.750–1.349) 0.970
 Esophageal/GI disease 186 (27.8) 1539 (9.5) <0.001 1.417 (1.083–1.854) 0.011
 Developmental delay 329 (49.3) 3255 (20.0) <0.001 1.637 (1.247–2.149) <0.001
 Seizure disorder 176 (26.3) 1435 (8.8) <0.001 1.381 (1.011–1.888) 0.043
 Cerebral palsy 170 (25.4) 1431 (8.8) <0.001 0.949 (0.688–1.309) 0.749
 Structural CNS abnormality 181 (27.1) 2070 (12.7) <0.001 1.236 (0.969–1.576) 0.088
 Neuromuscular disorder 307 (46.0) 3433 (21.1) <0.001 1.391 (1.090–1.776) 0.008
 Preoperative steroid use 16 (2.4) 166 (1.0) 0.001 1.166 (0.619–2.197) 0.635
 Nutritional support 143 (21.4) 1157 (7.1) <0.001 0.986 (0.711–1.367) 0.932
 Hematologic disorder 23 (3.4) 296 (1.8) 0.002 0.713 (0.386–1.315) 0.278
 Congenital malformation 330 (49.4) 4833 (29.7) <0.001 1.083 (0.871–1.348) 0.474
 Childhood malignancy 11 (1.6) 1.0) 0.092
 ASA-class ≥3 395 (59.1) 4768 (29.3) <0.001 1.513 (1.161–1.970) 0.002
Lab values, mean (SD)
 White cell count 7.3 (2.5) 6.9 (2.3) <0.001 1.043 (1.007–1.081) 0.019
 Hematocrit 40.3 (4.2) 39.9 (3.8) 0.009 0.996 (0.971–1.021) 0.723
 INR 1.1 (0.1) 1.1 (0.1) 0.433
Procedural factors
 Computer assistance, n (%)
  With CAS 21 (5.9a) 335 0.055 1.388 (0.807–2.388) 0.236
  Without CAS 647 (3.9b) 15,947
 Operative time 319 (112) 284 (109) <0.001 1.001 (1.000–1.002) 0.018
 LOS 6.4 (6.2) 5.3 (6.8) <0.001 0.992 (0.977–1.007) 0.303
 Total RVUs 66.1 (28.3) 60.1 (26.5) 0.017 1.004 (1.001–1.008) 0.014

aPercent of patients with CAS who were readmitted; bPercent of patients without CAS who were readmitted; Bold values indicate significance (P<0.05). Pulmonary comorbidities include ventilator dependence, asthma, chronic lung disease, chronic oxygen support, tracheostomy, or structural pulmonary or airway abnormalities. Cardiac comorbidities include previous cardiac surgery and cardiac risk factors. ASA - American Society of Anesthesiologists; RVUs - Relative value units; CAS – Computer-assisted surgery; GI - Gastric/intestinal; CNS - Central nervous system; SD - Standard deviation; OR - Odds ratio; CI - Confidence interval; LOS - Length of stay; INR - International normalized ratio

Part II

There were 288 AIS patients who underwent posterior spinal fusion at our institution (136 Fluoro, 152 TNT), which were matched and compared to 326 NAV patients from the NSQIP dataset. NAV patients were significantly younger than both Fluoro and TNT patients [Table 6]. 30-day complication rates were similar between all three groups. In the Fluoro group, four patients returned to the OR for superficial site infections, which were all resolved with I&D; one patient required increased pain management; and one patient had desaturation events requiring BiPAP. One patient also developed a DVT, but this occurred after 30 days. In the TNT group, two patients developed superior mesenteric artery syndrome, which resolved through gastric decompression; one patient developed hypotensive shock; and one patient developed wound dehiscence.

Table 6.

Comparison of clinical variables between navigated patients from the NSQIP dataset, fluoroscopy group, and “technique’n’technology” group utilizing the Airo CT navigation technology groups

NAV (n=326) Fluoro (n=136) TNT (n=152) P a P b P 3 P d
Age (years) 13.8 (11.1–16.5) 14.7 (13.3–15.9) 14.8 (13.4–16.3) <0.001 0.010 <0.001 0.450
Operative time (min) 323 (240–434) 304 (259–345) 247 (219–288) <0.001 0.050 <0.001 <0.001
LOS (days) 4 (3–5) 4 (3–5) 3 (2–4) <0.001 0.190 <0.001 <0.001
Transfusion, n (%) 236 (72.4) 30 (22.2) 41 (27.2) <0.001 <0.001 <0.001 0.335
Complications, n (%) 22 (6.8) 7 (5.2) 4 (2.6) 0.180 0.67 0.070 0.558

aP-value for overall group difference; bP-value for Fluoro to NAV; 3P-value for TNT to NAV; 4P-value for Fluoro to TNT. Data are presented as median and IQRs or counts and percentages when applicable. Bold values indicate significance (P<0.05). Fluoro - Fluoroscopy group; TNT - “Technique’n’technology” group utilizing the Airo CT navigation technology; NAV - Navigated patients from the NSQIP dataset; LOS - Length of stay; IQRs: Interquartile ranges

Median operative time was 323 min for NAV, which was significantly higher than 304 min for Fluoro and 247 min for TNT. Transfusion rates were also significantly higher for the NSQIP NAV group (72.4%) than the Fluoro (22.2%) and TNT (27.2%) groups but were statistically equivalent between the TNT and Fluoro groups. Median LOS for NAV was greater than that for TNT (4 vs. 3 days, P < 0.001).

Analysis of the fluoro versus TNT groups revealed similar pre- and post-operative Cobb angles with similar degrees of Cobb correction [Table 7]. The TNT group had greater postoperative kyphosis than the Fluoro group (27.9 vs. 24.6°, P < 0.001). The TNT group had less radiation time but had a greater radiation dose overall. Both groups had a median 13 levels fused (P = 0.390).

Table 7.

Comparison of radiographic and perioperative outcomes between fluoroscopy group and “technique’n’ technology” group utilizing the Airo CT navigation technology patients

Fluoro (n=136) TNT (n=152) P
Female, n (%) 105 (77.2) 109 (71.7) 0.290
Total radiation dose (mGy) 2.9 (1.9–4.3) 4.2 (1.6–12.9) 0.040
Total radiation time (s) 23.0 (15.4–33.0) 17.0 (9.4–22.6) 0.001
Preoperative major curve (°) 56.0 (50.0–63.5) 58.0 (54.3–63.9) 0.180
Postoperative major curve (°) 17.0 (12.2–22.9) 18.1 (12.7–24.8) 0.610
Cobb correction (%) 69.7 (59.9–78.7) 69.2 (59.4–80.1) 0.620
Preoperative kyphosis (°) 25.5 (17.0–36.2) 26.5 (15.6–37.5) 0.800
Postoperative kyphosis (°) 24.6 (18.0–31.0) 27.9 (18.1–37.6) 0.001
EBL (mL) 600 (400–700) 450 (300–700) <0.001

Data are presented as median and IQRs or counts and percentages when applicable. Bold values indicate significance (P<0.05). Fluoro - Fluoroscopy group; TNT - “Technique’n’ technology” group utilizing the Airo CT navigation technology; IQRs - Interquartile ranges; EBL - Estimate blood loss

DISCUSSION

Improvements in imaging technology and computer-assisted surgery have allowed spine surgeons to operate on increasingly complex deformity cases with greater accuracy.[15,16,17,18] However, short-term outcomes evaluating navigated pediatric deformity surgery remain poorly studied. This is the first large-scale database study to evaluate navigation as a predictor of outcomes in posterior deformity surgery in pediatric patients and to compare the nationally represented navigated cohorts' outcomes to those of fluoroscopy-only and navigated cases performed at a single institution.

In the present study, after adjusting for patient-related and procedural factors, navigation in posterior fusion for pediatric spinal deformity predicted a 92% increase in odds of reoperation as well as a 2.9-times and 3.2-times increase in odds of deep wound infection and sepsis/septic shock, respectively. However, after controlling for operative year in a separate analysis, navigation no longer predicted reoperation, but remained associated with deep wound infection and sepsis-related events. Site-related events were the most common reason for reoperation. While navigation was associated with greater rates of morbidity and transfusion in univariate analysis, adjusted analysis demonstrated similar odds of morbidity and transfusion following navigation.

Compared to our single-institution data utilizing the TNT approach to navigated pedicle screw placement, whereby screws are initially placed under freehand anatomic technique followed by CT-based navigation, the NSQIP NAV group had statistically similar complication rates, but significantly greater operative times and transfusion rates. Notably, the Fluoro and TNT groups both had similar transfusion rates compared to each other, but significantly lower transfusion rates compared to the NAV group. Other studies have found similar levels of blood loss between navigated and nonnavigated surgery.[16] Our findings suggest that, while navigation may be associated with an increased risk of infectious-related events on a national scale, factors on an individual level, such as learning curve, sterile technique, minimized number of CT spins, and operative efficiency and reduced operative time, can have a profound impact on outcomes.[19,20] The factors such as increased operating room personnel, intraoperative O-arm spins and frequent relocations into sub-sterile rooms, and increased setup time may ultimately pose an increased risk of accidental contamination and associated infectious-related events.

Further, while learning curve cannot be evaluated directly in the present study, the finding that reoperation no longer statistically differed between navigated and conventional groups after controlling for operative year suggests that improvements in navigated technology during study period and increased surgeon experience can maximize the benefits of navigation. In a learning curve study of navigated vertebral body tethering, Mathew et al. demonstrated a steep learning curve over a 5-year period whereby operative time, hospital stay, and blood loss decreased and suggested that evolving technology may play a notable role.[19]

Prolonged operative time has been associated with navigation in prior deformity studies.[15,21] In addition, a large meta-analysis found that operative time was about 30-min longer on average in navigated versus nonnavigated surgery.[16] In the present study, multivariate quantile regression demonstrated that navigation independently predicted a 44-min increase in median operative time. Interestingly, in the treatment of single-level degenerative disease, navigation and nonnavigated cases have been found to have similar operative times, suggesting that case complexity likely plays an important role.[22] Compared to the single-surgeon Fluoro and TNT patients, NAV was associated with significantly higher OR time.

Moreover, we found that navigation predicted an 8.2-point increase in median RVUs per case. Unadjusted analysis demonstrated that navigation was associated with fewer RVUs per minute compared to conventional surgery, suggesting that there is a significant mismatch between efficiency and reimbursement. However, when taking into account operative year as well as significant patient-related variables, navigation was no longer associated with RVUs per minute in multivariate analysis. This is the first study to compare RVUs per case and per minute between navigated and nonnavigated surgery.

Comparison between the Fluoro to the TNT groups revealed that the TNT group still had a higher overall radiation dose despite having a lower radiation time. Radiation exposure is of particularly importance in children. Meta-analyses have demonstrated higher radiation dose in navigated surgery.[16] In the pediatric cervical spine literature, nonnavigated O-arm technique has been demonstrated to be effective in evaluating screw malposition without subjecting patients to radiation doses as high as those seen in navigation.[23] Interestingly, the Fluoro and TNT groups both had similar postoperative Cobb angles and degrees of Cobb correction, suggesting that both techniques allow for adequate coronal correction.

An important limitation of this study is the lack of granularity in data inherent to the utilization of a national surgical database, with an inability of the dataset to capture individual surgeon experience.[24,25,26] It is possible that newer, less experienced surgeons, are more frequently utilizing navigated technologies, which could skew outcomes more favorably toward conventional surgery. Other surgeon- and patient-related factors may influence operative time, blood loss, and infection with and without the use of navigation. Nevertheless, the current study provides interesting data regarding the use of navigation in pediatric deformity surgery on the national scale, which is currently lacking in the literature. The NSQIP dataset also does not provide details regarding the technique in which navigation is being utilized or the number of CT spins. In addition, the dataset does not provide specific information about pedicle screw placement (e.g., cortical vs. traditional screws). Although navigated versus conventional pedicle screw accuracy is a well-studied topic, our study did not evaluate for screw accuracy, which would have provided additional discussion points.

CONCLUSIONS

On a national scale, navigation predicted an increased odds of reoperation and infectious-related events and yielded greater median RVUs per case but had longer OR time and fewer RVUs-per-minute. However, after controlling for operative year, RVUs-per-minute and reoperation rates were similar between groups. The NSQIP navigated surgery group was associated with significantly higher median operative time and transfusion rates compared to the single-institution fluoroscopy-only and freehand followed by navigation, or “TNT,” groups. Complication rates were similar between all three groups. These findings suggest that navigated technology could be utilized more efficiently on a national level and that learning curve, surgeon experience and technique, and improvements in technology can maximize the benefits of navigation. In addition, specific comorbidities and demographic factors, such as African − American race and Hispanic ethnicity, predicted poorer outcomes. The identification of such predictors can allow surgeons to identify and potentially target interventions for patients who are at risk.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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