Revisiting the Posterior Approach for Cervical Radiculopathy Utilizing Endoscopic Techniques: A Favorable Short-Term Outcome and Cost Comparison With Anterior Cervical Discectomy and Fusion

Key Findings

The current study is among the first comparing ACDF vs endoscopic posterior cervical foraminotomy/discectomy in cost of care and perioperative outcomes. Preoperatively, the 2 cohorts were similar in demographics and preoperative characteristics except for younger age and higher smoking status in the ACDF cohort. Overall costs were driven by the ACDF approach on multivariable analysis, which is not surprising given the cost of implants. Due to the 2.75-times higher cost of ACDF, an endoscopic cervical foraminotomy/discectomy revision rate requiring an ACDF of 64% is required for break-even cost. Perioperatively, ACDF was associated with increased operative time and length of stay but without a statistically significant difference in 90-day (global period) reoperation, revision, or complications. The rate of improvement in neurological symptoms was identical at 100% in both groups. These results suggest that posterior cervical endoscopic foraminotomy/discectomy is a safe, effective, and far less costly surgical alternative compared with ACDF for patients with unilateral cervical radiculopathy.

Invasiveness of Posterior Cervical Endoscopic Foraminotomy

Unilateral cervical radiculopathy is commonly treated with ACDF, and the literature has shown that posterior cervical foraminotomy/discectomy is equally effective for the treatment of unilateral radiculopathy.11–15 Endoscopic posterior cervical foraminotomy/discectomy is a less invasive approach that obviates the need for a motion-limiting spinal fusion, long-term risk to adjacent segments, or risks of dysphagia and hoarseness associated with ACDF.2–5 Notably, a randomized controlled trial comparing ACDF and endoscopic foraminotomy showed equivalent outcomes at 2 years postsurgery.15

Traditional open posterior cervical foraminotomy/discectomy tends to preserve motion and directly treat posterior compression while still allowing paramedian or lateral discectomy with a downside of a higher rate of neck pain secondary to wide subperiosteal muscle dissection that disrupts the paraspinal muscles including the multifidus muscles.7 In addition, there is a rich plexus of veins that often interferes with visibility.9 Similarly, tubular or microendoscopic posterior cervical foraminotomy/discectomy is performed via larger diameter tubes and is associated with more muscle dissection, worse operative angles with less ability to undercut and preserve the medial facet and SAP, and similar struggles with venous plexus during discectomy.16 Full posterior cervical endoscopic foraminotomy/discectomy, therefore, may strike the optimal balance between direct decompression of posterior pathology and/or anterior disc bulge, with preservation of motion and both dynamic and structural stability.

Cost Comparison

Our study found that ACDF costs were 2.75 times higher than posterior cervical endoscopic foraminotomy. As the United States has drastically different cost structures than most countries, more cost-conscious, single-payer systems such as Korea have had earlier implementation and innovation of endoscopy.10 Comparing costs between single-payer systems and private, employer-based U.S. systems is difficult. Furthermore, as only a handful of U.S. spine surgeons perform endoscopic cervical foraminotomies, and many cannot access their surgical costs, these data are valuable, and we hope they will lead to larger, multicenter studies comparing the 2 approaches. Sensitivity analysis showed that no observed variation in surgical costs or revision rates allowed ACDF to become less expensive than endoscopic foraminotomy/discectomy. An excess endoscopic foraminotomy/discectomy revision rate of 64% above ACDF revision rates was required before break-even costs, far higher than observed long-term foraminotomy vs ACDF revision rates,6 and with conservative assumptions that ACDF was performed for all revisions, and there were no ACDF failures. Overall, the fact that no observed input variability could make ACDF less costly than endoscopic foraminotomy on sensitivity analysis, and that only a 36% initial endoscopic foraminotomy-first success rate would be required for cost equipoise with current ACDF-first pathways, points to a low likelihood that the results would change if studied in other settings.

Drivers of Cost

We found that the ACDF technique was the primary driver of cost compared with endoscopic posterior foraminotomy after univariate and multivariable stepwise regression that initially included body mass index, age, race, gender, insurance, length of stay, and operating room time. Additionally, overhead costs also likely play a role between the operative costs at the general hospital (ACDF) and the hospital-owned surgery center (endoscopic cervical foraminotomy/discectomy). However, implant and overhead costs likely have similar cost pressures between large academic hospitals. While there are capital overhead costs associated with the endoscopic spine equipment, these costs are comparable with the operative microscope and traditional cervical operative equipment.21 Overall, the publishing of total surgical costs that includes implant, anesthesia, professional, and overhead costs is scarce in the literature and provides a useful analysis of the: (1) actual costs that underlying total treatment costs and charges billed to patient’s/insurance and (2) differences in techniques in hospitals vs surgery centers that are not adequately assessed by only variable cost evaluation.

Limitations

The current study is not without limitations. First, the retrospective, single-center nature of the study and relatively small sample size have inherent limitations, including generalizability. Second, the cost data are only applicable to our institution, yet we would submit that the cost results are likely applicable to most similar hospital systems. These limitations are likely applicable to any U.S. study regarding endoscopy given the relative rarity of endoscopic spine surgeons in the United States and the fact that any multicenter “cost” study would likely rely on Medicare-based reimbursement that does not account for actual cost or technical nuances of endoscopic vs traditional surgery. Additionally, our study results concur with previously published literature from other countries, making the single-center generalizability outcomes data less of a concern.12,22 Our focus on significant drivers of cost with multivariable analysis makes our results more generalizable to other hospitals that likely have similar cost pressures, even if they have slightly different baseline differences in implant purchasing power or overhead costs. Overall, the significant cost difference between ACDF and endoscopic foraminotomy/discectomy, which remains unchanged after sensitivity analysis, is unlikely to substantially change if studied in other U.S. hospitals. Third, the study has a relatively short follow-up period and can only be applied to the perioperative period. Due to its minimally invasive nature, endoscopic foraminotomy patients can return to daily function rapidly with fewer postoperative follow-up visits and naturally low opioid prescription requirements. In fact, the vast majority of our endoscopic foraminotomy patients only have a single postoperative follow-up appointment in the first 90 days and are, therefore, easily lost to follow-up unless they return with recurrent symptoms. The short follow-up period and relatively small sample inhibit tracking of longer-term pain outcomes. The durability of the posterior foraminotomy/discectomy and long-term reoperation rates cannot be assessed in this study, as our results only extend to the immediate postoperative period. Fourth, opioid prescription patterns vary significantly between surgeons without direct relation to surgical invasiveness.23,24 Due to surgeon prescription variability, this study is best equipped to show that endoscopic foraminotomy/discectomy can be performed without postoperative opioids rather than to compare opioid use with ACDFs, although this would be an interesting variable in larger, longer studies. Fifth, our study compares the cost of care for endoscopic cervical foraminotomies at the hospital-associated ASC vs outpatient ACDFs performed at the main hospital, with ACDF patient’s typically spending 1 night in the hospital. Although ACDFs are now more commonly being performed at ASCs, evidence suggests that a slim majority of ACDFs are still being performed in the hospital setting.25 Regardless, the cost difference found in our study far exceeds the average hospital cost per inpatient day and is unlikely to change if studied in other settings.26 Finally, we do not have an accepted patient-reported outcome metric, which also limits our generalizability.