Comparative Analysis of Anterior Cervical Discectomy and Fusion at a Single Level: Free-Hand Versus Navigation-Guided Approaches

Article information

J Minim Invasive Spine Surg Tech. 2025;10(1):124-130

Publication date (electronic) : 2025 April 30

doi : https://doi.org/10.21182/jmisst.2024.01760

Assil Mahamid^,1,*, David Maman^2,3,*, Summer Sofer², Marah Hodruj⁴, Arsen Shpigelman^2,3, Yaron Berkovich^2,3, Eyal Behrbalk^1,2

¹Department of Orthopedics, Hillel Yaffe Medical Center, Hadera, Israel

²Technion Israel Institute of Technology, Haifa, Israel

³Carmel Medical Center, Haifa, Israel

⁴Bnai-Zion Medical Center, Haifa, Israel

Corresponding Author: Assil Mahamid Department of Orthopedic Surgery at Hillel Yaffe Medical Center, Ha-Shalom St, Hadera, 3820302, Israel Email: dr.assilm@gmail.com

*Assil Mahamid and David Maman contributed equally to this study as co-first authors.

Received 2024 September 5; Revised 2024 October 15; Accepted 2024 October 16.

Abstract

INTRODUCTION

The landscape of spine surgery has dramatically shifted with the adoption of navigation technologies, which have significantly enhanced the precision and safety of surgical procedures [1]. In parallel, traditional free-hand techniques continued to develop, relying primarily on the surgeon’s expertise and anatomical familiarity. The integration of navigation systems into cervical spine surgery has been particularly transformative. The intricate anatomy of the cervical region demands high precision during surgery to avoid critical structures and minimize risks.

Anterior cervical discectomy and fusion (ACDF), first performed in 1958, remains a cornerstone surgical procedure for addressing cervical spine conditions such as degenerative disc disease, infections, and tumors [2]. Annually, this procedure is carried out more than 132,000 times across the United States [3]. The rise of medical technology has seen a gradual shift towards navigation-guided ACDF, which leverages real-time imaging to enhance precision and improve surgical outcomes.

Navigation technologies facilitate this by providing real-time, 3-dimensional (3D) visualizations that enhance the accuracy and consistency in screw placement [4], whereas free-hand ACDF relies solely on the surgeon's expertise and anatomical knowledge [5]. Despite this, navigation systems offer substantial benefits, especially in complex cases where anatomy is distorted or pathology is near critical neurovascular structures [6]. Intraoperative stereotactic navigation is increasingly used for accurate placement of spinal instrumentation and verification of anatomic landmarks under these challenging conditions [7].

Given the evolution of ACDF techniques and the significant annual volume of procedures, a detailed comparative analysis is essential. This study aims to utilize the National Inpatient Sample (NIS) database to meticulously compare the outcomes of free-hand versus navigation-guided ACDF in terms of complications, costs, mortality, and length of stay. These insights can be crucial for informing clinical decision-making, optimizing surgical techniques, and ultimately leading to better patient outcomes.

MATERIALS AND METHODS

This study utilized data from the NIS, a major public database on inpatient care managed by the Healthcare Cost and Utilization Project (HCUP). The NIS is a 20% sample of inpatient stays at HCUP-participating hospitals, translating to roughly 7 million admissions annually. This allows for generating national estimates using discharge weights included in the NIS data. The specific dataset employed in this study covered inpatient stays from January 1st, 2016, to December 31st, 2019, representing the most recent information available within the NIS at the time of the analysis.

The study was conducted under exempt status granted by the Institutional Review Board of Hillel Yaffe Medical Center, and the requirement for informed consent was waived due to the de-identified nature of the NIS dataset.

Each dataset entry, referred to as a "case," encapsulated a group of 5 patients; the analysis focused on 17,117 cases of one-level open anterior cervical discectomy surgery, representing 85,085 patients. Within this cohort, 560 surgeries were guided by navigation technology, constituting 0.66% of the total. Patients meeting specific International Classification of Diseases, 10th Revision (ICD-10) procedure codes for navigation-guided surgeries (8E09XBF, 8E09XBG, 8E09XBH) were included, while those with non-elective admissions, previous surgeries, or robotic interventions were excluded. Comorbidities and complications were identified via patient-specific ICD-10 codes.

We adopted propensity score matching to address disparities in variables such as ages and comorbidities between the navigation-guided and control groups. This statistical approach aimed to align the groups across various attributes, thereby fortifying the credibility of our analysis.

Due to the smaller size of the navigation group relative to the control group, we augmented the control group to be 20 times larger. This adjustment aimed to enhance the statistical robustness of our analysis while maintaining a balanced comparison between the groups. Through propensity score matching, we aligned the distribution of variables such as comorbidities, ages, sex composition, racial demographics, hospital sizes, and surgery years between the navigation-guided and control groups. This methodological refinement enabled a more thorough comparison and mitigated potential biases arising from initial group differences.

All analyses, including cross-tabulations and independent sample t-tests, were conducted, adopting a p-value threshold of less than 0.05 to establish statistical significance. Statistical analysis was conducted using IBM SPSS Statistics ver. 26.0 (IBM Co., Armonk, NY, USA). A list of ICD-10 codes used in this study is included in the Supplementary Material for reference.

RESULTS

Table 1 presents the demographic and clinical features of single-level ACDF surgeries, contrasting free-hand and navigation-guided techniques. Free-hand surgeries dominated 85,020, while navigation-guided procedures accounted for 560. Both groups exhibited differences in age and sex distribution, with statistically significant variations noted. Navigation-guided surgeries showed higher Medicare usage and lower reliance on private payers than the free-hand approach.

Table 1.

Demographic and clinical characteristics of single-level anterior cervical discectomy and fusion procedures: control vs. navigation-guided approaches

Table 2 compares comorbidity rates between the control and navigation-guided groups in single-level ACDF procedures. Most comorbidities showed similar prevalence between groups, except for chronic anemia and congestive heart failure, which were significantly different.

Table 2.

Comparison of comorbidities between control and navigation-guided groups in single-level anterior cervical discectomy and fusion procedure

Table 3 compares clinical outcomes between the control and navigation-guided groups. Mortality rates were low and similar between groups. There was no statistically significant difference in length of stay (p=0.082). However, there were significant differences in mean total charges (p<0.001), with navigation-guided procedures associated with higher costs.

Table 3.

Comparison of hospitalization outcomes and costs between control and navigation-guided groups in single-level anterior cervical discectomy and fusion procedures

We employed propensity score matching to ensure a fair comparison between the navigation-guided and control groups. This statistical technique effectively aligned variables such as ages, comorbidities, sex composition, and hospital sizes, enhancing the reliability of our analysis. Given the smaller size of the navigation group, we used a control group that is 20 times larger to maintain statistical accuracy. This adjustment facilitated a more comprehensive comparison, reducing potential biases and reinforcing the validity of our results.

Table 4 compares demographic and clinical characteristics after propensity score matching analysis (PSMA) between the control and navigation-guided groups in single-level ACDF procedures. The table includes parameters such as age, total surgeries, mortality rates, length of stay, and mean total charges, along with their significance levels. The data illustrate the effectiveness of PSMA in balancing the distribution of these variables between the 2 groups, enhancing the validity of our analysis. Notably, even after PSMA, navigation-guided procedures were associated with higher mean total charges compared to the control group by $7,341.

Table 4.

Comparison of demographic and clinical characteristics after propensity score matching between control and navigation-guided groups

Table 5 provides insights into postoperative complications following single-level ACDF procedures, comparing outcomes between the control and navigation-guided groups after PSMA. The data reveal differences in complication rates with acute kidney injury and pulmonary embolism, where navigation-guided procedures exhibited significantly higher rates compared to the control group (p=0.001 and p<0.001, respectively). However, no significant differences were observed in the rates of heart failure, acute coronary artery disease, pulmonary edema, venous thromboembolism, blood transfusion, surgical site infection, dural tear, or injury to the cervical spinal cord. The incidence of postoperative and intraoperative complications prior to PMSA in both groups is presented in Supplementary Tables 1 and 2, respectively.

Table 5.

Comparison of demographic and clinical characteristics after propensity score matching between control and navigation-guided groups

DISCUSSION

This study investigated the impact of navigation-guided surgery on clinical and economic outcomes. Compared to conventional surgery, navigation-guided surgery was associated with a significant increase in total costs (p<0.001). While hospital stay length remained comparable, navigation-guided surgery exhibited variations in the incidence of acute complications, including blood loss anemia and acute heart failure. Additionally, this approach resulted in higher mean total charges and a concerning rise in the rates of acute kidney injury and pulmonary embolism. These findings warrant further investigation to optimize cost-effectiveness and ensure patient safety in navigation-guided surgery. By analyzing these metrics, the study seeks to provide empirical evidence on the effectiveness and efficiency of navigation technologies in enhancing surgical precision and patient recovery.

Regarding the accuracy of the navigation technology, since our data lacks radiologic images, we assessed accuracy based on the absence of acute spinal injuries, as no such injuries occurred in any of the cases. This technology proved its accuracy of screw placement in the lumbar spine in comparison with the free-hand approach [8]. Concerning the posterior and lateral mass approach, one study demonstrated that navigation percutaneous posterior pedicle screw fixation could be performed safely, finding these constructs biomechanically superior with lower neurovascular complication rates comparable to the traditional lateral mass screw technique [9]. Another study demonstrated that navigated surgery can lead to higher accuracy and even shorter operating times than standard navigated operations [10,11].

The utilization of navigation systems in ACDF surgery presents both advantages and disadvantages. On the beneficial side, navigation systems, particularly intraoperative computed tomography-based 3D navigation, have been demonstrated to enhance the accuracy of plate and screw placement, potentially leading to improved alignment and superior clinical outcomes [12,13]. Moreover, real-time 3D visualization provided by navigation systems can be especially advantageous in complex cases or patients with challenging anatomy [12]. However, the use of these systems is also associated with certain drawbacks. Navigation systems can lead to prolonged operative times due to additional setup and intraoperative imaging requirements [1,4,6]. We hypothesize that the observed increase in complication rates may be attributed to these extended operative times inherent to navigation-guided procedures. This additional time likely stems from the need to set up navigation equipment while maintaining a sterile environment, a factor supported by previous studies that have demonstrated comparable or even longer operative durations with the use of navigation systems [14,15].

Furthermore, the high cost of acquiring and maintaining navigation systems poses a significant financial burden for healthcare institutions [5]. Lastly, there is a notable learning curve, requiring extensive training for surgeons and operating room personnel, which may initially prolong procedures and increase the potential for errors [4,7].

From a financial perspective, we identified a statistically significant difference in mean total charges between navigation-assisted and free-hand techniques. The analysis revealed a cost disparity of $7,341, favoring the free-hand approach. This finding aligns with existing literature, which suggests a trend of higher costs associated with spine navigation technology compared to traditional free-hand surgery [16,17]. The underlying principle is that more advanced surgical technologies often incur more significant implementation costs. As computer-assisted navigation becomes increasingly standardized and utilized in spinal surgeries, the economic burden on healthcare systems may rise due to the broader patient population undergoing these procedures [18]. The advantages of using this technology, such as enhanced anatomical visualization and higher accuracy, should be carefully balanced against the disadvantages, such as longer operative times and higher financial expenses. Additional long-term studies are necessary to assess the cost-effectiveness of this navigation approach. Evaluating long-term outcomes and financial impacts will provide a more comprehensive understanding of the value of using this technology in surgical procedures, including analyzing potential cost savings from reduced complications and hospital readmissions and considering the initial investment and ongoing operational expenses associated with the technology. Our findings on cost differ significantly from earlier published studies, many of which predate the last decade. Studies on navigation technology using the ACDF approach must address the financial aspect. These economic considerations raise pivotal questions about the cost-effectiveness of navigation surgery, prompting a nuanced evaluation of its benefits against financial investment [19].

Given the smaller size of the navigation group, we used a 20-times larger control group to maintain statistical accuracy. This adjustment facilitated a more comprehensive comparison, reducing potential biases and reinforcing the validity of our results.

Moreover, it allows a reduction in radiation exposure for the medical staff [17]. The superiority of screw placement accuracy in the lumbar spine achieved with navigation compared to free-hand techniques has been well-established [10,20]. Extending this advantage to the cervical spine, particularly in the posterior and lateral mass approaches, a study demonstrated the safe implementation of navigated percutaneous posterior pedicle screw fixation. This technique offered biomechanical superiority and comparable, potentially lower, neurovascular complication rates compared to the traditional lateral mass screw technique [21,22]. Concerning the ACDF approach, a recent study showed that navigation can safely and effectively restore the cervical vertebral sequence, fully release spinal canal compression, and promote patients' neurological recovery [23]. A study including 193 ACDFs performed with 3D navigation and 728 performed with fluoroscopy found that, after adjusting for demographics and surgical characteristics, 3D navigation was associated with less lateral plate deviation and longer operative times per interspace; however, there were no significant associations with angular plate deviation, length of stay, perioperative complications [12].

Mortality rates were low and comparable across both groups. While most complications showed no significant differences, navigation-assisted procedures were associated with a significantly increased risk of acute kidney injury and pulmonary embolism. Conversely, no significant differences were observed in surgical site infection, dural tear, or injury to the cervical spinal cord. The precise cause remains elusive within our extensive dataset; however, a plausible explanation may be the potential prolongation of surgeries associated with navigation assistance, which could lead to an increased risk of pulmonary embolism and subsequent renal implications. This finding necessitates a critical reevaluation of the purported benefits of robotic systems, particularly in light of adverse outcomes such as heightened postoperative complications [24].

This study represents the first to utilize ICD-10 procedure codes in ACDF with navigation. Compared to its predecessor, ICD-9, the ICD-10 system offers a significantly more granular level of detail, incorporating approximately 68,000 diagnosis codes and 87,000 procedure codes. This enhanced specificity facilitates the precise identification of diseases and conditions, thereby improving the accuracy of research outcomes [25,26] The adoption of ICD-10 has been associated with enhanced quality of coded data, supporting more reliable data collection [27]. As a globally recognized system, ICD-10 enables international comparisons of morbidity and mortality, playing a critical role in epidemiological research and global health surveillance.

This study acknowledges certain methodological limitations, primarily using broad ICD-10 codes within an extensive dataset. Nevertheless, it provides a valuable large-scale analytical perspective. While granular details on individual patients are lacking, the considerable statistical power afforded by the vast sample size substantiates the credibility of our findings. The absence of operative and anesthesia times in the NIS data represents a significant limitation, as these variables could have influenced several key outcomes reported in the study. Without accounting for these factors, our ability to comprehensively interpret the results may be constrained. It is crucial to recognize the inherent trade-off between the depth of patient-specific data [16] and the robust insights gained from analyzing a comprehensive dataset that includes thousands of free-hand versus hundreds of navigational approaches in ACDF surgeries.

CONCLUSION

Our findings indicate that while free-hand procedures were more prevalent, navigation-guided surgeries were associated with significantly higher usage of Medicare and increased total charges. Propensity score matching was employed to balance demographic and clinical characteristics, confirming the robustness of these findings. Notably, navigation-guided techniques showed a higher incidence of specific postoperative complications, such as acute kidney injury and pulmonary embolism, despite similar mortality rates and lengths of hospital stay compared to the free-hand approach. These results underscore the need for careful consideration of the costs and benefits associated with navigation-guided ACDF surgeries, particularly in light of the increased financial burden and risk of certain complications.

Supplementary Material

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