With the evolution of new technologies in spine surgery, there are increasing concerns of both effectiveness and costs. In 2012, US healthcare spending reached $2.8 trillion, or approximately $8,915 per hospitalized patient, up 175 % from a decade ago ($1.6 trillion) [1–4]. With the continued increases in healthcare expenditures, medical and surgical interventions are being increasingly scrutinized for their cost-effectiveness to both the patient and provider. Minimally invasive surgery (MIS) serves to lessen soft tissue injury and hasten postoperative recovery [1, 2]. This leads to less time in the hospital, fewer hospital-associated complications, and less pain medicine requirement, which all serve to lower both patient and provider costs. In addition, with hastened recovery, patients could potentially incur less indirect costs as they would return to work faster. While these results are suggested, there is limited evidence to support that these theoretical advantages are actually occurring. Specifically, high-quality reports have shown that despite the elimination of open procedure-related complications, new complications are associated with MIS [5, 6]. The goals of this chapter are to review the literature on costs and economic implications of the MIS lateral approach to the spine (which include extreme lateral interbody fusion [XLIF; Nuvasive, San Diego, CA], direct lumbar interbody fusion [DLIF], and lateral lumbar interbody fusion [LLIF]).

In the value-guided era of healthcare, comprehensive cost analysis is paramount in guiding clinical decision making and patient care. The heterogeneity in costing methodology used in various studies leads to conflicting conclusions on the cost-effectiveness of an intervention for a specific diagnosis [7]. This heterogeneity includes variability between studies on whether both direct and indirect costs are calculated as well as whether the costs are being determined from the perspective of the hospital, the payer, or society. Specifically, costs from the hospital perspective include direct costs, costs of staff, supplies, utilities, and rent; however, the costs usually exclude those of the surgeon or anesthesiologist because those costs are covered by insurance companies. Costs from the payer perspective (e.g., insurance companies) include payments to the hospital and physicians (i.e., direct costs). Costs from the societal perspective include indirect costs in addition to the payer perspective direct costs [7]. The other area of heterogeneity that exists in the cost-effectiveness spine surgery literature is regarding the time frame in which costs are measured. High upfront costs associated with surgery may lead to the conclusion that surgery is not cost-effective in a 2–3 month or even 12-month time frame. Extending the follow-up time, however, to 2 years and beyond may allow for different conclusions [7]. MIS lateral fusion, similar to other fusion procedures, is associated with significant costs [8]. Given the recent popularity of this approach, it is important to ask if these costs are justified compared to open fusion procedures.

Barbagallo et al. [8] conducted a systematic review to determine the comparative effectiveness of XLIF/DLIF/LLIF versus posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion (TLIF) in patients with degenerative spine conditions. Five studies were included. Patients who underwent LLIF experienced significantly less blood loss (two studies), length of stay (three studies), and mortality risk (one study) than patients who underwent PLIF/TLIF. For each additional level operated on via LLIF, there was a 59 % increase in the complication risk. Upon further analysis, no predictive factors on a worse prognosis after LLIF were identified. Overall, the authors concluded that insufficient evidence exists to compare the procedures. Of the evidence that exists showing that LLIF leads to fewer complications or reoperations than PLIF/TLIF, it is low quality. Given the paucity of evidence on outcomes of XLIF/DLIF/LLIF, assessing the procedure’s cost-effectiveness is difficult.

Only two studies have previously been performed specifically evaluating the costs and outcomes associated with XLIF/DLIF/LLIF [5, 6]. Deluzio et al. [5] performed a controlled cost comparison at a single institution between open two-level PLIF (n = 102) and minimally invasive two-level XLIF (n = 109) in patients with degenerative spine conditions. Costs included operating room (OR) services and “direct patient costs” and were retrospectively collected as actual hospital costs. These “direct patient costs” included transfusions, reoperations, readmissions, physical therapy, and additional diagnostics. The authors showed cost savings of 9.6 %, or about $2,563 per patient in the perioperative period ($24,208 XLIF, $26,771 PLIF), which was defined as the surgery and first 45 days postoperatively. This cost savings was due to significantly decreased hospital stay (1.2 days XLIF, 3.2 days PLIF) and decreased time in physical therapy. The same authors published a more complete version of their results 2 years later and found a statistically significant cost savings of about $2,800 between the cohorts. The study did not report on quality of life outcomes and, thus, was not a cost-effectiveness analysis.