Comparing trends and outcomes of minimally invasive transforaminal lumbar interbody fusion (TLIF) procedures: A retrospective analysis

Abstract

Purpose

To describe utilization patterns of minimally invasive transforaminal lumbar interbody fusion (TLIF) procedures and to evaluate indirect healthcare utilization indicators such as revisions, infection, and complication rates for various TLIF techniques.

Methods

A retrospective analysis using the Pearldiver database was conducted to identify patients who underwent TLIF between 2010 and 2022. The patient population was stratified into four groups: TLIF with an open approach (TLIF-Open), TLIF with stereotactic navigation (TLIF-NAV), TLIF with the assistance of an operating microscope (TLIF-MI), and TLIF utilizing navigation and operating microscope (TLIF-Combined). Revision, infection, and complication rates were analyzed and compared between each technique with open procedure as the reference procedure using multivariate analysis.

Results

Over the past 13 years, TLIF-Open procedures showed a consistent decrease in utilization, while TLIF-NAV, TLIF-MI, and TLIF-Combined approaches remained relatively stable without experiencing the same dramatic increase as the decline in TLIF-Open procedures. Multivariate regression analysis revealed, TLIF-NAV and TLIF-MI procedures were associated with a higher likelihood of undergoing revision surgeries within 30 days post-operatively, with TLIF-NAV also being linked to a higher risk of infection within 30 days. The TLIF-MI group had a lower likelihood of acute kidney injury (AKI), while the TLIF-NAV group had a lower likelihood of pneumonia and urinary tract infections (UTI).

Conclusion

There has been a noticeable shift in the utilization of TLIF procedures from open to minimally invasive approaches. While stereotactic navigation demonstrates favorable outcomes in terms of complications, surgeons must carefully consider infection risks and revision rates.

1. Introduction

For more than a century, spine surgeons have explored surgical techniques to treat vertebral disc-related neurological problems. Transforaminal lumbar interbody fusion (TLIF), and later, minimally invasive TLIF are options to treat spinal disorders. Each iteration reduced musculoskeletal structure disturbance and manipulation of the spinal nerves, leading to better patient outcomes.¹ More recently, computer-assisted navigation has been developed and has been shown to improve instrumentation accuracy in lumbar spine surgeries;² however, the operational expenses can be substantial.3, 4

These computer navigation systems help surgeons more accurately place pedicle screws without compromising patient and perioperative outcomes.5, 6 Even though the operating microscope has not been linked to an increased risk of infection, increased operating due to the use of operating microscope may elevate post-operative infection rates.7, 8

The aim of this study was to describe the utilization patterns of minimally invasive transforaminal lumbar interbody fusion (TLIF) procedures and to evaluate the indirect healthcare utilization indicators such as revisions, infection, and complication rates for various TLIF techniques. In addition, post-operative healthcare utilization costs for each minimally invasive approach was also explored.

2. Methods

A retrospective analysis using the Pearldiver database was conducted to identify patients who underwent TLIFs between 2010 and 2021. The current procedural terminology (CPT), and international classification of diseases (ICD) 9/10 codes were used to identify and stratify the populations (Table 1). The patient population was stratified into four groups: TLIF with an open approach (TLIF-Open), TLIF with stereotactic navigation (TLIF-NAV), TLIF with the assistance of an operating microscope (TLIF-MI), and TLIF utilizing navigation and operating microscope (TLIF-Combined). The trends of utilization for each of these procedures performed were determined, and their percentage change for each year was also calculated. The average demographic characteristics (including age, gender, Elixhauser-Comorbidity Index (ECI) score, average reimbursement on the record (paid) and insurance plans) for patients undergoing each of these procedures were determined and compared to capture the demographic differences in populations utilization each of these techniques. 30-day and 90-day revision rates, infection rates, and complication rates (including acute kidney injury (AKI), cardiac arrest, deep vein thrombosis (DVT), nerve injury, pneumonia, pulmonary embolism (PE), hematoma, and urinary tract infection (UTI)) were determined and compared using multivariate regression analysis while controlling for age, gender, ECI score and region (aOR). A p-value <0.05 was considered significant. To assess the total 30-day costs rendered post-operatively for following each of these procedures associated with the utilization of facility, surgeons, anesthesia, neuromonitoring, hospital services, investigations, ICUs, radiology, physical therapy, and office visits for the next 30 days were determined and compared for each procedure.

Table 1.

Current procedural terminology (CPT), and international classification of diseases (ICD) 9/10 codes used to identify and stratify the populations.

Variables	Codes
TLIF-Open	CPT-22630
TLIF-NAV	CPT-22630, CPT-61783
TLIF-MI	CPT-22630, CPT-69990
TLIF-Combined	CPT-22630, CPT-69990, CPT-61783

3. Results

3.1. Trends

The query revealed evolving trends of TLIF procedures, with shifts in utilization patterns for each approach over the past decade (2010–2022) (Fig. 1). While TLIF-Open procedures exhibited a persistent downward trend (21,062 cases in 2010 to 902 cases in 2022), TLIF-NAV, TLIF-MI and TLIF-Combined maintained a relatively stable trajectory and has not seen as dramatic of a rise as there was decline in the TLIF-Open procedures.

Fig. 1.

Utilization trends of minimally invasive vs open TLIF procedures between 2010 and 2022.

3.2. Demographics

The data revealed statistically differences between all 4 groups for age, ECI score, reimbursements (paid) and insurance plans (p-value <0.05) (see Table 2). In terms of age, TLIF-NAV patients tend to be older (60.18 years), followed by TLIF-combined (58.83 years), TLIF-Open (58.17 years) and TLIF-MI (57.39 years). Similarly, the highest comorbidity burden was seen in TLIF-NAV (ECI 4.91), followed by TLIF-Open (ECI 3.09), TLIF-MI (ECI 2.67), and TLIF-Combined (ECI 3.71). The distribution of gender was not statistically significant between the groups. TLIF-Combined techniques had the highest overall mean reimbursement followed by TLIF-NAV, TLIF-Open and TLIF-MI. Notably, the “commercial” plan had the highest utilization across all four groups: 51222 participants in TLIF-Open, 5244 in TLIF-NAV, 5990 in TLIF-MI, and 625 in the combined TLIF cohort.

Table 2.

Demographic characteristics of patients undergoing minimally invasive and open TLIF procedures.

	TLIF-Open	TLIF-NAV	TLIF-MI	TLIF-Combined	P-value
Age (years)	58.17	60.18	57.39	58.83	<0.05
ECI score	3.09	4.91	2.67	3.71	<0.05
Reimbursements ($)	1464.50	5710.59	2427.63	9636.53	<0.05
Gender
Male	31576	3393	3434	372	0.14
Female	43625	4435	4754	510
Plan
cash	36	∗	∗	11	<0.05
commercial	51222	5244	5990	625
government	1230	231	156	48
Medicaid	3102	442	225	21
Medicare	19032	1872	1750	176
unknown	579	35	65	∗

3.3. Complications

Multivariate regression analysis revealed that TLIF-NAV (OR 1.31 [1.25, 1.38]) followed by TLIF-MI (OR1.11 [1.06, 1.16] were more likely to undergo revision surgeries up until 30-day post-operatively (p-value <0.05) (Table 3). Similarly, TLIF-NAV (OR 3.02 [2.10, 4.35]) was also more likely to have an incidence of infection within 30-days (p-value <0.05).

Table 3.

Revision and Infections rates between minimally invasive TLIF procedures at 30- and 90-day intervals.

	aORa
	TLIF-Open	TLIF-NAV	TLIF-MI	TLIF-Combined
Revisions
30-day	reference	1.31 [1.25, 1.38]	1.11 [1.06, 1.16]	0.95 [0.83, 1.08]
90-day	reference	1.05 [0.93, 1.19]	0.82 [0.71, 0.94]	0.75 [0.50, 1.13]
Infections
30-day	reference	3.02 [2.10, 4.35]	0.33 [0.11, 1.05]	1.75 [0.43, 7.17]
90-day	reference	1.58 [0.97, 2.58]	0.41 [0.13, 1.29]	1.90 [0.46, 7.76]

^aAdjusted for age, gender, region and ECI score.

The results reveal an overall lower likelihood of AKI in the TLIF-MI, and lower likelihood of pneumonia and UTI in the TLIF-NAV group (Table 4).

Table 4.

Complication rates between minimally invasive TLIF procedures at 30 and 90-day intervals (TLIF-Open as the comparison group).

	aORa
	TLIF-NAV	TLIF-MI	TLIF-Combined
AKI 30	0.97 [0.82, 1.16]	0.71 [0.55, 0.90]	0.46 [0.21, 1.03]
AKI 90	0.93 [0.80, 1.08]	0.75 [0.61, 0.93]	0.50 [0.26, 0.98]
Cardiac arrest 30	0.94 [0.49, 1.81]	1.21 [0.58, 2.54]	1.25 [0.17, 9.06]
Cardiac arrest 90	0.77 [0.43, 1.35]	1.21 [0.66, 2.20]	1.62 [0.40, 6.62]
DVT 30	2.04 [1.43, 2.90]	0.65 [0.32, 1.32]	2.30 [0.85, 6.24]
DVT 90	0.92 [0.82, 1.05]	1.09 [0.96, 1.23]	0.85 [0.57, 1.24]
Nerve Injury 30	4.347 [0, ∞]	1.257 [0, ∞]	2.377 [0, ∞]
Nerve Injury 90	0.57 [0.35, 0.92]	0.75 [0.49, 1.15]	0.29 [0.04, 2.06]
Pneumonia 30	0.79 [0.64, 0.98]	0.98 [0.78, 1.22]	1.13 [0.65, 1.97]
Pneumonia 90	0.65 [0.61, 0.68]	1.01 [0.96, 1.07]	0.75 [0.64, 0.89]
PE 30	0.76 [0.52, 1.12]	1.21 [0.87, 1.68]	1.90 [0.94, 3.85]
PE 90	0.63 [0.54, 0.74]	1.14 [0.99, 1.31]	0.89 [0.58, 1.34]
UTI30	0.81 [0.70, 0.94]	0.98 [0.84, 1.14]	0.64 [0.39, 1.05]
UTI90	0.69 [0.66, 0.73]	1.06 [1.01, 1.11]	0.83 [0.71, 0.96]

^aAdjusted for age, gender, region and ECI score.

3.4. Healthcare utilization

The cost comparisons are detailed in Table 5. The costs are significantly lowest for facility, anesthesia utilization in the TLIF-NAV group. Surgeon costs are significantly lower for TLIF-MI group. In contrast, neuromonitoring, hospital services and investigations, ICU, radiology, physical therapy, and office visits are lowest for the TLIF-Combined group.

Table 5.

Post-operative 30-day Healthcare utilization related to diagnosis only for minimally invasive TLIF procedures when compared to TLIF-Open procedure.

Healthcare encounter	Odds Ratio [95 % Confidence Interval]
	TLIF-NAV	TLIF-MI	TLIF-Combined
Facility	0.71 [0.62, 0.82]	0.85 [0.75, 0.97]	0.58 [0.08, 4.21]
Surgeon	0.89 [0.80, 1.00]	0.76 [0.68, 0.86]	0.45 [0.06, 3.24]
Anesthesia	0.71 [0.65, 0.78]	1.11 [1.03, 1.21]	0.85 [0.26, 2.73]
Neuromonitoring	0.65 [0.54, 0.78]	1.47 [1.30, 1.67]	5.20−05 [1.64−74, 1.65+65]
Hospital services & investigations	0.79 [0.75, 0.82]	1.07 [1.02, 1.12]	0.34 [0.17, 0.66]
ICU	0.75 [0.69, 0.81]	0.94 [0.88, 1.01]	2.46−05 [1.72−47, 3.50+37]
Radiology	0.89 [0.84, 0.95]	1.15 [1.08, 1.23]	0.44 [0.23, 0.83]
Physical therapy	0.87 [0.83, 0.91]	1.04 [0.99, 1.08]	0.44 [0.23, 0.86]
Office visits	1.14 [1.07, 1.21]	1.10 [1.03, 1.17]	0.33 [0.18, 0.61]

4. Discussion

The data from this study suggest that the minimally invasive approaches of performing TLIF surgeries have maintained a consistent upward trend post-2017, while open procedures have shown a significant decline. However, the adoption of minimally invasive approaches has remained gradual despite comparable outcomes to open procedures. While the shift to navigation-assisted techniques stems from benefits like enhanced anatomical visualization, better outcomes, and reduced damage to the surrounding neurovascular structures, their slow adoption could be due to their complexity and the need for costly hardware and software infrastructure.9, 10

TLIF-NAV demonstrates cost reductions across various healthcare utilization categories, except for office visits, and boasts advantages in complication risks. However, concerns arise around 30-day revision, infection, and DVT risks within this patient group. In computer-assisted navigation, visualization using tubular retractor is restricted. This may result in incomplete decompression compared to open TLIF. This may explain the higher 30-day revision rates however evidence suggests that complication rates may improve with surgeon experience.11, 12 There is limited evidence regarding infection rate and other complications in computer assisted navigation in spine surgery,¹³ but computer-assisted navigation in knee replacement surgery also led to drawbacks like extended surgery duration impacting infection and thromboembolic rates.¹⁴

Revision rates, infection rates, and complication rates were comparable between TLIF-MI and TLIF-Combined procedures when compared to TLIF-open procedures. For TLIF-Combined procedures, complication advantages coupled with clear cost-benefit, helps establish its superiority. In contrast, TLIF-MI procedures showed a cost disadvantage and comparable complication profile in comparison to TLIF-open procedure. When weighed against overall average reimbursements for each procedure (outlined in demographics table), open procedure ranked as the most economical, followed by TLIF-Combined, TLIF-NAV, and TLIF-MI respectively. While TLIF-NAV and TLIF-combined offer post-operative cost and complication benefits, the value of TLIF-MI remains uncertain based on our study findings.

To the best of our knowledge, this study stands as the first endeavor to explore trends and cost comparisons across various approaches for TLIF procedures. While numerous studies have undertaken outcome comparisons, a notable gap lies in the inclusion of cost considerations, which play a pivotal role in influencing surgical practice changes for healthcare professionals. Furthermore, this study aims to comprehensively evaluate and compare revision and complication rates across various approaches, rather than focusing solely on a singular approach. A strength of this study is its substantial patient population, a facet that has often posed a challenge in investigations involving TLIF-MI, TLIF-NAV, and TLIF-Combined procedures. These approaches are frequently available only at select hospitals, which can limit the size of patient cohorts in other studies.

The limitations of this study include the inherent constraints of utilizing insurance claims databases, where the employed codes may not always precisely correspond to the procedures under scrutiny. Despite our utmost effort to use the most specific codes available, it is plausible that the codes for TLIF-MI, TLIF-NAV, and TLIF-Combined procedures might not be widely adopted, potentially leading to an incomplete capture of their actual utilization rates. Additionally, in future studies, reasons for revision can be explored and inflation can also be accounted for when comparing cost benefits.

5. Conclusion

In conclusion, there has been a noticeable shift in the utilization of TLIF procedures from open to minimally invasive approaches. Minimally invasive techniques broadly lead to less postoperative healthcare utilization compared to the traditional open TLIF. While computer assisted navigation demonstrates favorable outcomes in terms of complications, surgeons must carefully consider infection risks and revision rates. These risks, however, are likely to improve as more surgeons gain experience using non-open techniques.

Guardian/Patient's consent

This study did not require consent from any patients.

Ethical committee statement

This study did not require approval by the Biomedical Institutional Review Board of The Ohio State University.

Funding statement

The authors of this article declare a financial competing interest, as this investigation was funded by Prosydian, the former manufacture of FIBERGRAFT products. None of the authors or study staff have any direct or intrinsic conflicts of interest or relationships with Prosidyan, Inc. All authors are direct students or employees of The Ohio State University Wexner Medical Center and Ohio University. Prosidyan, Inc. Had no role in the collection, analyses, or interpretation of data; in the writing of this manuscript; or in the decision to publish the results.

CRediT authorship contribution statement

Hania Shahzad: Conceptualization, Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing. Maximillian Lee: Conceptualization, Data curation, Investigation, Methodology, Writing – original draft, Writing – review & editing. Frank Epitropoulous: Conceptualization, Writing – review & editing. Nazihah Bhatti: Conceptualization, Writing – review & editing. Varun K. Singh: Conceptualization. Venkat Kavuri: Conceptualization, Writing – review & editing. Elizabeth Yu: Conceptualization, Methodology, Supervision, Writing – review & editing, NAB, Formal analysis, WKS, Writing – review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.