Assessment of Clinical Outcomes and Pain Management of Single-Level Lumbar Laminectomy Between Unilateral Biportal Endoscopic, Tubular, and Open Approaches
Article information
Abstract
Objective
While minimally invasive surgical procedures have been shown to reduce postoperative pain and recovery time compared to an open surgical approach, few studies have also compared pain management, particularly involving the use of unilateral biportal endoscopy (UBE).
Methods
Patients who underwent single-level laminectomy through a UBE, open, or tubular technique were chart-reviewed for up to 90 days for perioperative outcomes, including opioid and nonopioid utilization. The chi-square test and analysis of variance were used to analyze differences in characteristics and outcomes between groups. The post hoc Tukey test and multinomial regression were conducted when significance was found in initial tests.
Results
In total, 184 patients were included in the study (110 open, 44 tubular, 30 UBE). The UBE patients were the oldest. Post hoc analysis showed that UBE and tubular patients had significantly lower blood loss than the open group (p<0.05). Moreover, UBE surgery was associated with significantly longer operative times than both tubular and open surgery (p<0.05). No significant differences were observed in complications, 90-day readmissions, or return to the operating room. Postdischarge, patients in the open and tubular groups had higher rates of acetaminophen and cyclobenzaprine prescriptions, respectively, than the UBE group (p<0.05). Postoperative opioid use at 2 weeks significantly differed among groups. When controlling for age and preoperative opioid use, multivariate regression revealed that patients who underwent decompression by UBE had lower odds of postdischarge opioid use at 2 weeks than the open group (53.20% vs. 21.70%; odds ratio [OR], 0.267; 95% confidence interval [CI], 0.09–0.79; p=0.017) and the tubular group (50.0% vs. 21.70%; OR, 0.268; 95% CI, 0.08–0.91; p=0.038). No statistically significant between-group differences were observed for ongoing opioid use at the 6-week and 3-month time points.
Conclusions
Patients who underwent UBE had significantly lower odds of postdischarge narcotic use at 2-week follow-up than those undergoing the open and tubular approaches.
INTRODUCTION
Extensive evidence has shown that elective decompressive surgery for severe lumbar spinal stenosis (LSS) provides greater resolution of neurologic symptoms and functional status compared to conservative treatment [1-3]. Traditionally, open laminectomy has been the gold standard of surgical management. While committing to an open approach is effective in relieving radicular symptoms, it typically requires substantial tissue and bony removal, contributing to increased levels of postoperative back pain and instability [4,5]. Alternatively, minimally invasive techniques (MIS) serve to mitigate surgical trauma by providing greater preservation of the posterior anatomy with noninferior decompression [6-9]. MIS techniques make use of advanced optical instruments and narrow surgical corridors to provide effective operation of the pathoanatomy within a smaller working area. The microendoscopic system is a popular MIS strategy that utilizes sequential dilators to gently retract encountered tissue with placement of a small-diameter tube for visualization of the lesion. Surgical instruments are subsequently inserted through this tube to interact with the spinal and neural elements [10,11]. Various comparative studies comparing MIS and open approaches have reported that MIS can help reduce blood loss, shorten length of hospitalization, and improve patient reported outcomes [12-15].
Unilateral biportal endoscopy (UBE) is an emerging MIS technique for treatment of LSS. The addition of a second channel when performing UBE provides enhanced instrumental manipulation and field of vision as compared to the traditional uniportal design [10,16]. UBE makes use of 2 small same sided incisions about the medial margin of the pedicle at both the cephalad and caudal levels of the targeted interlaminar space for precise placement of the visualizing and working portals. The outflow of continuous irrigation helps open up the potential working space and allows for an ultra-magnified view of the lesion through the endoscope. Much like other techniques, early reports of UBE decompression show that it is effective in rectifying preoperative stenotic symptoms [16-18].
While substantial evidence shows MIS techniques can provide improved procedural and patient outcomes following decompression of LSS, few studies also report on postoperative pain management and narcotic use. To the best of our knowledge, this is one of the first studies that seeks to compare opioid dependence with other clinical outcomes between UBE and other approaches.
MATERIALS AND METHODS
1. Study Design
An Institutional Research Board of NYU Grossman School of Medicine (authorization number: 18-00668) approval was performed for a single academic institution. Patients ≥ 18 years of age undergoing single-level lumbar laminectomy for treatment of LSS were included in the study. All cases were collected starting from July 2018. Patients were excluded if they had baseline intervertebral instability, evidence of spinal infection or tumor, or had lumbar discectomy due to disk herniation. Groups were made based on whether the surgical technique consisted of either an open, tubular, or UBE approach. Usage of each method was determined based on the discretion and experience of the operating surgeon. While evidence has shown the benefits of a multimodal anesthesia protocol in enhancement of postoperative pain management and recovery [19], the analgesic regimens were standard and equivalent among the 3 groups as set by protocol at our institution.
2. Data Collection
Patients in each group were retrospectively chart-reviewed up to 90 days for comparison of clinical characteristics. Baseline patient variables included age, sex, body mass index (BMI), American Society Anesthesiologists physical status [20], and previous lumbar surgery. Preoperative opioid use was distinguished if reported within 30 days prior to surgery. Surgical characteristics were reviewed from the operative note documented by the primary surgeon. These included laterality of decompression (if ipsilateral or bilateral), target level, estimated blood loss, and operative time. Other perioperative outcomes included length of stay, complications, readmissions, and return to operating room.
In order to provide robust assessment of patients’ pain management postoperatively, both opioid and nonopioid pain medication prescriptions were recorded from patient records up to 90 days. To measure narcotic consumption, the total oral morphine milligram equivalent (MME) for each prescribed opioid was calculated by multiplying the dosage (mg) by the pill count by the appropriate MME conversion factor as per the Centers for Medicare and Medicaid Services [21]. Postoperative opioid utilization was tracked at the 2-week, 6-week, and 3-month time points based on if they reported continued use at their clinical follow-up.
3. Statistical Analysis
All statistical analyses were performed using IBM SPSS Statistics ver. 25.0 (IBM Co., Armonk, NY, USA) statistical software. Comparisons between open, tubular, and UBE groups were conducted using chi-square analyses and analysis of variance tests. Post hoc tests including Tukey and multinomial regression were used to determine individual group differences following initial tests. The level of significance for all performed tests was set at p<0.05.
RESULTS
1. Study Population
A total of 184 patients (110 open, 44 tubular, 30 UBE) were enrolled in the study. In the general cohort, 42% of patients were female, mean age was 67 years, and mean BMI was 28.18 kg/m2. Single-level lumbar laminectomy was performed from L2–S1, with L4–5 being the most common level (75.5%).
2. Baseline and Perioperative Outcomes
UBE patients were found to be significantly older compared to open and tubular (71.77 years vs. 65.85 years vs. 65.11 years; p=0.042, p=0.049, respectively). Though not statistically significant, patients who underwent open surgery had a higher prevalence of preoperative opioid use compared to the other groups (22.7% vs. 11.4% vs. 7.7%, p=0.058). Amongst surgical outcomes, post hoc analysis revealed that both the tubular and UBE groups experienced significantly reduced blood loss compared to open (25.91 mL vs. 24.82 mL vs. 44.32 mL, both p<0.05). However, compared to the 2 other approaches, UBE was associated with significantly longer operative times (168.37 minutes vs. 98.31 minutes vs. 120.16 minutes, both p<0.001) (Table 1). Across the 3 groups, no differences were found in complications, length of stay, 90-day readmissions, or reoperation (Tables 1 and 2).
Baseline and surgical characteristics
Ninety-day perioperative and clinical outcomes
3. Assessment of Postoperative Opioid Use and Pain Management
In regards to nonopioid analgesics, post hoc revealed that significantly more patients in the open and tubular groups were provided acetaminophen following discharge compared to UBE (37.3% vs. 31.8% vs. 10.0%, p=0.009, p=0.037 respectively) and open had a substantially higher amount administered within 90 days than UBE (16,113.87 mg vs. 3,500.00 mg, p=0.041). Though tubular patients had higher rates of prescription of cyclobenzaprine compared to open and UBE, the difference in the overall amount prescribed was non-significant. No other differences were found in comparison of other commonly prescribed medications including gabapentin, diclofenac, meloxicam, and tizanidine.
Moreover, patients in each group received narcotics at equivalent rates and amounts up to 90 days. When comparing postoperative opioid dependence, there was a significant difference at 2 weeks. After controlling for age and preoperative usage, multivariate regression revealed that the UBE group had reduced odds compared to open (53.20% vs. 21.70%; odds ratio [OR], 0.267; 95% confidence interval [CI], 0.09–0.79; p=0.017) and tubular groups (50.0% vs. 21.70%; OR, 0.268; 95% CI, 0.08–0.91; p=0.038) (Figure 1). Past 2 weeks, no differences were found in ongoing opioid use at 6-week and 3-month time points across each group (Table 3).
Comparison of opioid usage at 2-week, 6-week, and 3-month time points. Solid black represents the open group, dashes represent the tubular group, and solid gray represents the unilateral biportal endoscopy (UBE) groups. *p<0.05, corresponding to a statistically significant difference.
Analysis of postoperative pain management
DISCUSSION
Understanding the various dynamics that impact trends of opioid use is necessary to safeguard patients from associated adverse outcomes. The widespread prescription of opioids in medical practice has fueled a concerning epidemic of dependency and misuse [22]. While their heightened potency can provide greater short-term relief of severe pain compared to other analgesics, mismanagement and prolonged use of opioids can place patients at higher risk of addiction, inadequate pain relief, and fatal overdose [23]. Given the clinical burden imposed by opioid use disorder [24], it underscores the need for physicians to identify improved strategies to better manage patients’ pain. This dilemma is especially dire in spine surgery where patients typically require substantially more opioid requirements postoperatively compared to other specialties [25]. While multimodal analgesic protocols have helped serve a role to protect against long-term narcotic usage [26], opioid utilization patterns are still largely impacted by the invasiveness of the performed procedure.
As demonstrated in the present study, despite experiencing longer surgeries, after controlling for previously described risk factors of prolonged opioid consumption including age and preoperative opioid use [27,28], patients who underwent UBE had significantly reduced odds of narcotic use at 2 weeks compared to open and tubular surgery. Alongside narcotic consumption, UBE was associated significantly lower rates of acetaminophen and cyclobenzaprine prescription within the early postoperative period compared to the other surgical groups.
While extended use of self-retaining retractors for exposure in open surgery can place undue pressure to the surrounding tissue and result in muscle atrophy and “failed back syndrome” following surgical intervention [15,29], MIS techniques that are able to reduce tissue dissection en route to the spine can help decrease patients' pain levels, shorten recovery time, and reduce reliance on pain medication. Multiple studies that compare open and MIS surgeries have established similar findings to our own in the comparison of postoperative pain requirements between each approach. Mobb et al. [30] observed that the average total of MME consumed following tubular bilateral laminectomy was significantly lower than open surgery. Additionally, Parker et al. [31] and Adogwa et al. [32] demonstrated that trends of narcotic use between MIS and open were also synonymous following fusion, as patients who underwent MIS transforaminal lumbar interbody fusion (TLIF) were able to be weaned from their narcotic prescriptions at earlier time points compared to open TLIF.
Moving further, UBE is designed to potentially serve as a less invasive alternative to the tubular retractor system by providing improved visualization of the anatomy given the narrow working space of the cannula in tubular techniques. In addition, UBE allows for greater instrumental maneuverability through a wider range of operative angles as compared to the tubular approach which can be limited by the restricted mobility of the working cannula. Despite these proposed benefits, there have been mixed reports in the literature relating to each approach’s comparative effectiveness. A pooled meta-analysis conducted by Zheng et al. [33], showed that at both the immediate postoperative and long-term time points, UBE and microendoscopic tubular techniques had no difference in visual analogue scale leg and back scores or disability. Comparatively, in another recent meta-analysis examining the clinical efficacy of each technique for treatment of single-level stenosis, it demonstrated that use of UBE contributed to significantly improved patient reported pain and functional status when compared to the percutaneous tubular approach [34]. In our own analysis, much like in our comparison with open surgery, UBE was also associated with a significantly lower incidence of ongoing opioid usage at 2 weeks. Overall, though there was no difference in opiate usage at the 6-week and 3-month time points with the other groups, our results exemplify that UBE has the potential to improve pain control for patients requiring laminectomy compared to other notable approaches in the immediate postoperative period.
Despite the proposed advantages of UBE, important considerations need to be made before UBE can be fully adopted. For surgeons who have less experience, mastery of endoscopic surgery can be a challenging endeavor requiring further practice and training. Unlike like other traditional methods, UBE requires greater dexterity to make use of the working and camera channels in either hand, while simultaneously referring from the viewing screen rather than the surgical field [35]. While the rates of complications are relatively low when performing UBE, it is still important to consider the distinct risk factors associated with its operational setting. Elevated levels of hydrostatic irrigation within the intrathecal space can increase a patient’s epidural and intracranial pressures and heighten the odds of postural headaches and dysreflexia postextubation [36]. It is suggested that a lower pump water pressure of about 25–30 mmHg should be maintained to reduce the risk of increased intracranial pressures and associated postoperative back pain when looking to enlarge the working space during surgery [37]. Continuous inflow of the saline liquid is important to prevent blurred vision of the surgical site and protect against edema-related irritation to the multifidus muscles and other adjacent tissues in the case of stagnant water circulation [37,38]. Proper triangulation and communication of the viewing and working portals is also necessary to not only obtain efficient tissue removal but also to reduce the risk of irrigation stagnation due to accumulated fluid and tissue debris [39].
Furthermore, the continual inflow of irrigation can also make it difficult for surgeons to ascertain adequate hemostasis, making hematoma formation more likely if residual bleeding at the surgical site is not properly controlled [35,40]. Particularly, within our UBE cohort, of the 2 patients that required reoperation after index surgery, both experienced a postoperative hematoma (6.7%). One patient, despite successful resolution of preoperative symptoms on postoperative day 1 following L4–5 decompression, subsequently developed acute left leg pain that required emergent admission to the Emergency Department for intervention. In the other patient who also had L4-5 decompression, they developed new left dorsiflexion weakness and foot drop postoperatively. Magnetic resonance imaging of the lumbar spine revealed an organized hematoma in the L4–5 space of both patients that caused significant thecal sac compression.
Outside of patients who needed reoperation, 2 other patients in our UBE group experienced neurologic deficit after surgery, including one who experienced worsening weakness in his lower extremities and another who reported bilateral foot numbness. While there was no significant difference in complications of this sort between other groups, it is important to note that committing to a MIS approach such as UBE may limit the amount of room needed to complete a full decompression of the impinged nerves and should be accounted for during preoperative planning.
Nevertheless, while some procedural aspects of UBE can place patients at higher risk of certain complications, surgical and patient outcomes can be optimized with advances in surgeon skill and experience.
There are multiple limitations with respect to the present study. The retrospective study design has inherent flaws that allow for potential confounding in data collection. Secondarily, UBE was a relatively new procedure performed by a limited number of surgeons at our institution causing our study to suffer from smaller sample size. We also recognize that our primary outcome of ongoing patient opiate usage during their follow-up visit may be susceptible to bias given its reliance on self-reported medication use. Furthermore, for the purposes of the study, we provided a multimodal assessment of trends in patients' opioid intake and nonopioid requirements. However, given limited collection of quality-of-life questionnaires at our institution, we did not use any direct patient reported measures that would help in the evaluation of postoperative pain. Lastly, while we assessed patient’s early postoperative course up to 90 days, the clinical significance of our findings can be improved with longer follow-up.
CONCLUSION
Lumbar decompression as performed through UBE is a significant development towards surgical safety and enhanced recovery. While traditional spine surgery often necessitates narcotic usage after surgery, this study demonstrates that following UBE, patients had reduced opioid dependence within the early postoperative period compared to those who underwent other approaches in single-level laminectomy. Utilizing minimally invasive endoscopic techniques presents an advantageous opportunity for surgeons to provide adequate relief of patient symptoms and help diminish pain medication requirements postsurgery. Further evaluation of UBE should be conducted in larger studies with longer follow-up to aid its continued use in surgical treatment of LSS.
Notes
Conflict of Interest
JYK, DHH, and HSK are member of the Editorial Board of Journal of Minimally Invasive Spine Surgery & Technique, are the author of this article. However, they played no role whatsoever in the editorial evaluation of this article or the decision to publish it. All Authors have no conflict of interest to declare.
Funding/Support
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.