What's New in Spine Surgery.

Abstract

Over the past 2 years, the COVID-19 pandemic has impacted the entire health-care profession, and spinal surgery had to adjust along with it. Although it may take years to truly assess the overall effect, early trends have clearly pointed toward a patient demand for telemedicine. Additionally, as COVID strained our hospitals and diverted critical resources away from elective surgical procedures, non-time-sensitive cases have been increasingly pushed out to outpatient surgical centers. Decreased inpatient elective surgical capability has also forced more patients to pursue extended nonoperative treatment modalities. Although it remains too early to determine the long-term impact of these shifts, we expect future studies to examine these issues extensively. This annual update on spine surgery includes an examination of peer-reviewed literature for all spinal conditions, in addition to abstracts presented at annual society meetings, over the past year. We chose these articles due to their potential to impact and advance our profession, with a preference toward the highest levels of evidence. Spondylotic Cervical Myelopathy Several interesting studies published recently added to our understanding of optimal surgical treatment for spondylotic cervical myelopathy. In the Cervical Spondylotic Myelopathy Surgical (CSM-S) randomized clinical trial, Ghogawala et al. compared the impact of anterior surgery with that of posterior surgery on patient outcomes1. In a select population in which clinical equipoise existed (exclusion of patients with kyphosis of >5°, ossification of the posterior longitudinal ligament, or segmental kyphotic deformity), 1-year and 2-year Short Form-36 (SF-36) Physical Component Summary (PCS) scores were not different between the 2 groups. The authors did identify a higher complication rate in the anterior surgery group, with dysphagia predominating. The major complication rates did not differ. Interestingly, in the nonrandomized analysis comparing laminoplasty, posterior cervical fusion, and anterior cervical fusion, the patients who underwent laminoplasty fared significantly better in physical function, complication rate, and resource utilization. Posterior cervical fusion is more commonly performed in the United States, and a recent study demonstrated that laminoplasty is likely underutilized despite growing evidence for improved performance metrics2. Current literature has mixed results with regard to determination of the optimal lower instrumented vertebra (LIV) in long posterior cervical fusions. In addressing the question of crossing the cervicothoracic junction, Truumees et al.3 evaluated patient-reported outcomes, radiographic outcomes, and revision rates in fusions stopping at C6/7 or T1/2 in a retrospective analysis of 264 patients with at least a 2-year follow-up. Patient-reported outcome measures improved equally in both groups. Radiographic outcomes were similar between groups, with both groups demonstrating similar improvement in cervical lordosis. The study did not detect a difference in revision rates, but was not powered to do so. Patients who underwent fusions into the thoracic spine did have more blood loss and longer operative time. Similarly, in a retrospective cohort study with a 4-year follow-up, Guppy et al. did not identify a difference in reoperation rates for adjacent segment disease4 or pseudarthrosis5 when cervical fusions were stopped at C7 or T1/T2. In the absence of extenuating factors, stopping at C7 may be a reasonable option given the lower morbidity and complication rate, although further work is needed in this area. Cervical Radiculopathy Numerous studies have been published comparing cervical disc arthroplasty with anterior cervical discectomy and fusion (ACDF). However, many of these studies may have been biased by industry sponsorship and a lack of blinded outcome assessment. The Norwegian Cervical Arthroplasty Trial (NORCAT) was designed as a blinded and randomized clinical trial of 136 patients comparing patient-reported outcomes after ACDF or cervical disc arthroplasty for single-level disease6. The patients and surgeons were blinded, with the treatment arm revealed to the surgeon only after neurologic decompression was completed. Both groups demonstrated a significant improvement in the Neck Disability Index (NDI) at 5 years, without a difference observed between groups. Secondary outcomes, including neck pain, arm pain, and adjacent segment disease, were not different between groups. The reoperation rate was not significantly different between groups, and nearly all reoperations were at the index level. Only 1 patient underwent reoperation for adjacent segment disease at 5 years. This study demonstrates that clinical outcomes are likely independent of implant choice; however, the effect on adjacent segment disease needs to be addressed with longer-term follow-up. The 10-year Investigational Device Exemption (IDE) trial data for the Bryan and Mobi-C cervical disc arthroplasty devices are now available. In a study comparing adverse events between the Bryan cervical disc arthroplasty and ACDF, Loidolt et al. demonstrated a similar rate of adverse events over a 10-year period7. The rate of revision surgery at the index level was not significantly different between the 2 groups. The rate of adjacent level surgery in the ACDF group trended higher (15.8% compared with 9.7%) but did not reach significance at 10 years. Additionally, the 10-year outcomes from the Mobi-C IDE trial were published8. This study was limited by lack of an ACDF control group and had an approximately 73% follow-up rate from the original cohort. At 10 years, the authors identified a rate of revision surgery of 5.1% at the index level and 4.3% at the adjacent level. No serious adverse events were reported between 7 and 10 years. One of the most common symptoms after anterior cervical surgery is dysphagia. In a meta-analysis of 7 randomized controlled trials, Garcia et al. evaluated the dysphagia rate after ACDF with prophylactic administration of local or intravenous corticosteroid9. The study provides moderate-quality evidence that the administration of corticosteroids reduces the dysphagia rate and severity after ACDF. A subgroup of studies on the pseudarthrosis rate did not identify a difference. No infections were reported in this meta-analysis. In a recent, well-designed, randomized, and double-blinded controlled trial, Kim et al.10 corroborated these results: after undergoing multilevel ACDF, patients received retropharyngeal corticosteroid or placebo. Dysphagia was assessed with validated outcomes. The corticosteroid group had significantly better scores at all time points up to 1 month. These results suggest that corticosteroid administration likely reduces dysphagia rates, although the effect on pseudarthrosis remains to be fully elucidated. Lumbar Disc Herniation and Lumbar Degenerative Conditions Lumbar disc herniation remains a common clinical problem11. Several recent studies have examined options for the management of lumbar disc herniation. In a randomized controlled trial, Wilby et al. compared microdiscectomy with transforaminal epidural corticosteroid injection in patients with persistent radicular pain for <1 year secondary to disc herniation12. The authors found that there were no significant differences in pain scores between the epidural injection group and the surgery group, although 18% of the injection group underwent a surgical procedure prior to the completion of the study. The authors also posited that a surgical procedure is less cost-effective than an epidural injection, although this work is ongoing. In a systematic review and meta-analysis, Wei et al. compared open microdiscectomy, microendoscopic discectomy, percutaneous endoscopic discectomy, tubular discectomy, and percutaneous discectomy13. The authors found no significant differences between most approaches, except that percutaneous endoscopic discectomy had the best safety and efficacy, although this review was limited by the heterogeneity of the included studies. Ran et al. compared computed tomography (CT)-navigated percutaneous endoscopic discectomy with open microdiscectomy in 68 patients and found that the percutaneous discectomy group reported less postoperative back pain and the percutaneous approach generated lower serum markers of muscle trauma14. In a systematic review and meta-analysis, Gadjradj et al. found that moderate-quality evidence supports percutaneous transforaminal endoscopic discectomy as an equivalent treatment to open microdiscectomy, but there is a paucity of high-quality evidence comparing the 2 approaches15. Additionally, the topic of annular repair or other implants to reduce reherniation rates has been reexamined in the last 2 years. In a systematic review, Rickers et al. found a trend toward improved outcomes with annular repair. In contradistinction to the prior study, the authors also found that percutaneous discectomy performed the worst of all current surgical approaches, although, overall, there were no significant differences between treatments16. Additionally, the risk of bias was high in 15 of the 32 included studies. The debate with regard to the optimal management protocol for lumbar degenerative spondylolisthesis has continued lately. Heemskerk et al.17 compared open transforaminal lumbar interbody fusion (TLIF) and minimally invasive surgery (MIS)-TLIF for patient-reported outcomes, and Droeghaag et al.18 compared open TLIF and MIS-TLIF for cost-effectiveness. Heemskerk et al. found that MIS-TLIF and open TLIF had equivalent outcomes at the 2-year follow-up; Droeghaag et al. found that MIS-TLIF is more cost-effective than open TLIF. These results suggest that MIS-TLIF may be an important tool in the long-term management of lumbar degenerative spondylolisthesis. However, in a meta-analysis of 7 studies, Zhang et al. found that oblique lateral interbody fusion with supplementary posterior fixation yielded better improvements in symptoms compared with MIS-TLIF and was associated with a shorter operative time19. Furthermore, the type of posterior fixation for lumbar fusion remains controversial. In a systematic review and meta-analysis, Chang et al. compared traditional pedicle screws with cortical-based trajectory screws for the treatment of lumbar degenerative spondylolisthesis in patients who underwent interbody fusion20. The authors found that cortical screws were associated with decreased operative time and less blood loss during the surgical procedure, but the overall fusion rates were similar at 1 year. Additionally, Zhu et al. performed a systematic review and meta-analysis comparing MIS-TLIF and endoscopic TLIF, which demonstrated the noninferiority of the endoscopic approach compared with traditional minimally invasive techniques21. The applications of navigation and robotics continue to rapidly expand in the field of spinal surgery. Fu et al.22 and Zhou et al.23 both performed meta-analyses comparing the freehand placement of pedicle screws with robotic-assisted placement. Both studies found significant improvements in pedicle screw accuracy, including reduced violation of the cephalad facet joint and intraoperative radiation dose, with robotic assistance, although revision rates for screw malpositioning were similar in the latter article. Klingler et al. performed a randomized trial of fluoroscopically assisted MIS-TLIF and navigated TLIF and found that the type of navigation used in the study did not significantly reduce radiation exposure to the surgeon, while simultaneously increasing radiation exposure to the patient24. Therefore, the role of navigation and robotics is still being developed. There has also been increasing interest in single-position prone lateral lumbar interbody fusion as an option for patients requiring surgical stabilization for spondylolisthesis. Walker et al. performed a retrospective review of 30 patients with spondylolisthesis undergoing either prone or lateral decubitus lateral interbody fusion with posterior instrumentation25. The authors found that the prone position yielded significantly improved segmental lordosis compared with the traditional position. Additionally, Guiroy et al. performed a systematic review comparing these approaches and found that single-position lateral decubitus trended toward shorter operative time and hospital stay, although only 4 studies were included26. Interestingly, in a separate systematic review and meta-analysis, Mills et al. examined lateral decubitus compared with the prone position without repositioning and found that the single-position lateral decubitus reduced operative time and radiation exposure compared with the prone position, and the improvement in segmental lordosis was higher in the prone group27. However, pedicle screws placed using the lateral decubitus position had a higher rate of complications. Perioperative Pain Management There has been increasing interest in the utilization of local or regional anesthesia for pain control in patients undergoing lumbar spinal surgery. Erector spinae plane blockade continues to gain traction in this regard. In randomized controlled trials, Jin et al.28 examined the efficacy of an erector spinae plane block in patients undergoing lumbar laminoplasty, and Zhu et al.29 and Goel et al.30 examined the efficacy of an erector spinae plane block in patients undergoing single-level lumbar fusion. The authors found that erector spinae plane blockade resulted in significantly reduced postoperative pain scores, reduced opioid consumption, and higher patient satisfaction, suggesting that erector spinae plane blockade should become more routinely utilized in the perioperative period. Liposomal bupivacaine injection is an additional multimodal pain management technique to reduce postoperative pain and opioid consumption. Nguyen et al. performed a systematic review of retrospective cohort studies and randomized controlled trials investigating this technique and found that lower-quality evidence supports its use and moderate-quality studies were equivocal31. The authors maintained that higher-quality studies are needed before the efficacy of this technique can be fully appreciated. Multimodal anesthesia and various enhanced recovery after surgery (ERAS) postoperative pain management protocols have been developed to expedite patient recovery and improve satisfaction after spinal surgery. Recently, there have been several high-quality studies adding to the data on this topic. Soffin et al. published a trial of 56 patients randomized to either the ERAS protocol after lumbar fusion or traditional postoperative pain management, finding decreased opioid consumption and improved patient-reported pain scores in the immediate postoperative period with the ERAS protocol32. However, significant clinical impact was not proven with the ERAS protocol, which was possibly related to the small sample size. In a randomized controlled trial, Kraiwattanapong et al. similarly evaluated multimodal drug infiltration in the postoperative wound bed, demonstrating that this technique reduced postoperative pain scores and opioid consumption33. Sharaf et al. performed a randomized controlled trial comparing postoperative physical therapy with and without neural mobilization in patients who underwent lumbar decompression for stenosis; the authors found that the addition of neural mobilization improved outcomes across all patient-reported outcome measures34. Lastly, Ma et al. performed a prospective randomized trial evaluating the utility of postoperative spinal orthoses after MIS-TLIF35. The authors found that the use of a postoperative orthosis had no significant effect on the Oswestry Disability Index (ODI) or visual analog scale pain score at 6 or 12 months after MIS-TLIF. Additionally, the orthosis had no effect on the fusion rate at the final follow-up. Adult Spinal Deformity Surgical decision-making for patients with adult spinal deformity is complex. In several recent studies, authors have examined the risk-and-benefit calculation that aids our surgical indications, patient optimization, and preoperative counseling. The Prospective Evaluation of Elderly Deformity Surgery (PEEDS)36 study illustrates the potential benefit of spinal deformity surgery: this prospective, multicontinental study evaluated disability (ODI) in patients ≥60 years of age who underwent spinal deformity surgery. The authors demonstrated that, after an initial recovery period, 70% of patients experienced at least 10% improvement from their baseline disability, which was sustained at 2 years. Meanwhile, approximately 25% of patients reported no change from baseline and approximately 5% of patients reported worsening of the disability. Importantly, although there was an overall significant improvement in disability, the mean ODI of 27% at 2 years was still worse than normative values, and was consistent with moderate disability. This article also stratified the shift in ODI based on preoperative ODI deciles, which is a useful counseling tool for shared decision-making. Similar findings were identified in the 5-year outcomes reported by the Scoli-RISK-1 Study Group37. This study was limited by a 5-year follow-up rate of 28%, but identified a significant improvement in patient-reported outcomes, with 62% of patients having a clinically meaningful improvement in the ODI score. Numerous studies have shown the complication profile of deformity surgery. The 5-year results from the Scoli-RISK-1 Study Group demonstrated worse lower-extremity motor scores in 9.3% of patients who were available for follow-up at 5 years38. This rate was improved from 14% at the time of hospital discharge and was unchanged from 2 years postoperatively. In a recent study, Lakomkin et al.39 helped to contextualize the surgical invasiveness of deformity surgery by comparing it with other major operations. Using a variation of the validated Postoperative Morbidity Survey score, the authors added length of hospital stay and operative time to develop the novel Surgical Invasiveness and Morbidity Score (SIMS). Using the National Surgical Quality Improvement Program (NSQIP) database and controlling for comorbidities, the authors compared SIMS across major surgical procedures. Adult spinal deformity surgery fared better than coronary artery bypass grafting, abdominal aortic aneurysm repair, and cystectomy, performed similarly to mitral valve replacement, and was, overall, worse than prostatectomy, total shoulder arthroplasty, and hip fracture fixation. This study provides an intuitive counseling tool for patients considering adult spinal deformity surgery. Several studies have shown the importance of patient frailty as a predictor of outcomes and complications. Passias et al.40 demonstrated that frailty was independent of chronological age in predicting positive outcomes in adult spinal deformity surgery. Patients ≥70 years of age who were not frail fared better than elderly patients who were frail or severely frail. Gum et al.41 demonstrated that the cost of quality-adjusted life-year (QALY) was impacted more by patient frailty than by surgical invasiveness. Frail and severely frail patients had significantly and incrementally higher costs per QALY than non-frail patients. Surgical invasiveness did not have a substantial impact on cost per QALY. The authors recommended focusing on patient optimization with respect to modifiable risk factors to improve cost optimization. These studies help to understand the risk and benefit of adult spinal deformity surgery and provide an increased awareness of patient factors that may impact outcomes. Nonoperative Treatments Spine surgery continues to evolve with the rest of the surgical profession, and, as many have proven, high-quality randomized controlled trials are difficult to perform with surgical procedures. In contrast, our interventional pain colleagues may be better positioned to conduct studies within this gold standard of evidence-based medicine. Their ability to do so, coupled with an increase in the nonoperative treatment environment, has created an exponential growth across the United States at a time when our patients were hesitant to seek hospital-based care. A thorough discussion of all available pain management procedures is beyond the scope of this update, but we believe that it is particularly important that all orthopaedic surgeons understand the basics behind these procedures and the early evidence to support their use. We do advise the reader that each of the studies in this section was industry-funded. The minimally invasive lumbar decompression (mild) procedure is approved by the U.S. Food and Drug Administration (FDA) for the treatment of neurogenic claudication and gained approval for reimbursement by the U.S. Centers for Medicare & Medicaid Services (CMS) in 2017. The procedure uses a small portal to remove part of the lamina and ligamentum flavum using radiographic assistance. Most recently, in 2021, Deer et al. published the 6-month results of a randomized controlled trial comparing the mild procedure with conventional medical management and found the mild procedure to have superior results, albeit in very early results42. Multiple interspinous devices are currently available on the market, and we have seen an increased use among our pain management colleagues. These devices have an established role in the management of neurogenic claudication, but their specific indications continue to evolve. Schenck et al. recently reported the results of their 5-year randomized controlled trial of interspinous devices compared with decompressive surgery and found similar results, but with a higher risk of reoperation within the first 2 years following use of interspinous devices43. Intraosseous basivertebral nerve ablation procedure was approved by the FDA in 2016 for the treatment of chronic low back pain in patients with disc degeneration and Modic end plate changes. This procedure has recently demonstrated positive results. Fischgrund et al. performed a double-blinded randomized trial, finding that the ablation of the basivertebral nerve yielded continued improvement in pain and function at a mean of 6.4 years postoperatively in this challenging patient population44. Telemedicine in Spine Surgery With the COVID-19 pandemic, nearly the entire spine community saw a decrease in surgical procedures and an increase in virtual health options. The implementation of virtual examinations became necessary, and there has been exponential growth within virtual health publications. For the spine, most of the literature focused on performing the clinic visit and examination, with relatively few articles evaluating the long-term outcomes of doing so. Several authors validated the performance of the virtual examination, with an emphasis on the neurologic examination44-46. Upcoming Events Similar to the rest of the world, the spine community looks forward to getting back together with in-person meetings. Over the past 2 years, we have leveraged multiple different virtual platforms and expect to see continued growth of this important technologic advance forced by the pandemic. Although this has been a welcomed consequence of the pandemic, it does not replace the interaction among colleagues meeting in person. At the time of this writing, all future society meetings are currently planned to be in-person. Please join us at the North American Spine Society Annual Meeting in October 2022 in Chicago, Illinois; the Cervical Spine Research Society Annual Meeting in November 2022 in San Diego, California; the Scoliosis Research Society Annual Meeting in September 2022 in Stockholm, Sweden; the Lumbar Spine Research Society Annual Meeting in April 2023 in Chicago, Illinois; the Spine Summit in Spring 2023; and the American Academy of Orthopaedic Surgeons Annual Meeting in March 2023 in Las Vegas, Nevada. Evidence-Based Orthopaedics The editorial staff of JBJS reviewed a large number of recently published studies related to the musculoskeletal system that received a higher Level of Evidence grade. In addition to articles cited already in this update, 6 other articles relevant to spine surgery are appended to this review after the standard bibliography, with a brief commentary about each article to help guide your further reading, in an evidence-based fashion, in this subspecialty area. Evidence-Based Orthopaedics Austevoll IM, Hermansen E, Fagerland MW, Storheim K, Brox JI, Solberg T, Rekeland F, Franssen E, Weber C, Brisby H, Grundnes O, Algaard KRH, Böker T, Banitalebi H, Indrekvam K, Hellum C; NORDSTEN-DS Investigators. Decompression with or without fusion in degenerative lumbar spondylolisthesis. N Engl J Med. 2021 Aug 5;385(6):526-38. In a noninferiority design study, Austevoll et al. evaluated all patients with lumbar degenerative spondylolisthesis with a slip of ≥3 mm who were randomized to undergo either decompression alone or decompression and fusion. The magnitude of anterolisthesis >3 mm and evidence of a dynamic nature were not incorporated into their analysis. The primary outcome was an improvement of the ODI score by 30%. At 2 years, an equivalent proportion of patients had a clinically important improvement of the ODI score: 71.4% in the decompression-only group and 72.9% in the decompression and fusion group. Also at 2 years, reoperation rates trended higher in the decompression-only group at 12.5% than in the decompression and fusion group at 9.1%, but this difference was not significant. This study was primarily limited by the heterogeneity of the included patients, as the magnitude and dynamic nature of degenerative spondylolisthesis were not included in the analysis. Longer-term reoperation rates will be useful in understanding the durability of decompression alone in the setting of degenerative spondylolisthesis. Ultimately, this study adds useful information to the debate about fusion for degenerative spondylolisthesis, but falls short of narrowing down the subgroups of patients who will benefit most from decompression and fusion compared with decompression alone. Donnally CJ 3rd, Patel PD, Canseco JA, Divi SN, Goz V, Sherman MB, Shenoy K, Markowitz M, Rihn JA, Vaccaro AR. Current incidence of adjacent segment pathology following lumbar fusion versus motion-preserving procedures: a systematic review and meta-analysis of recent projections. Spine J. 2020 Oct;20(10):1554-65. The risk of adjacent segment degeneration at adjacent levels to lumbar fusion remains a clinical concern. Motion-preserving surgery has been developed to potentially mitigate this risk. Donnally et al. performed a systematic review comparing these techniques and the reported rate of adjacent segment pathology. The authors found no significant differences in adjacent segment disease or reoperation between groups, although the weighted analysis demonstrated lower odds of adjacent segment degeneration in the motion-preserving group. The quality of included studies was low. Bottom line: there still is no scientific consensus on whether motion-preserving surgery yields decreased adjacent segment disease. Hughes H, Carthy AM, Sheridan GA, Donnell JM, Doyle F, Butler J. Thoracolumbar burst fractures: a systematic review and meta-analysis comparing posterior-only instrumentation versus combined anterior-posterior instrumentation. Spine (Phila Pa 1976). 2021 Aug 1;46(15):E840-9. In a systematic review and meta-analysis, Hughes et al. compared posterior-only stabilization with combined anterior-posterior fixation for unstable lumbar burst fractures. Posterior-only instrumentation had improved length of stay, operative time, and blood loss but worse loss of deformity correction at final follow up. Patient-reported outcomes were not significantly different between groups. The literature remains largely inconclusive on which surgical approach is optimal. Johansen TO, Sundseth J, Fredriksli OA, Andresen H, Zwart JA, Kolstad F, Pripp AH, Gulati S, Nygaard ØP. Effect of arthroplasty vs fusion for patients with cervical radiculopathy: a randomized clinical trial. JAMA Netw Open. 2021 Aug 2;4(8):e2119606. Johansen et al. performed a randomized clinical trial comparing single-level ACDF with cervical disc arthroplasty. Patients were blinded to treatment, and surgeons were blinded to treatment until neurologic decompression was completed. The primary outcome was the NDI, and the secondary outcomes were arm and neck pain scores, quality of life, reoperation rate, and adjacent segment disease. There were 136 patients enrolled, with 83.8% follow-up at 5 years. NDI scores significantly improved in both groups, without a difference observed between groups. No differences were noted in reoperation rate or adjacent segment disease. This study demonstrated that neck disability scores were not significantly different between groups within 5 years. Implications for adjacent segment disease and reoperation warrant longer-term follow-up. Lin L, Cheng S, Wang Y, Chen X, Zhao G, Wang Z, Jia X, Ke Z. Efficacy of intrawound treatments to prevent surgical site infection after spine surgery: a systematic review and network meta-analysis. Pain Physician. 2021 Sep;24(6):E709-20. Lin et al. performed a systematic review and network meta-analysis of 33 studies (although only 6 were randomized controlled trials) and found that the addition of vancomycin powder in the wound after spinal surgery, as well as povidone-iodine solution and a combination of the 2 treatments, yielded significant decreases in surgical site infection. As corroborated by this systematic review, vancomycin powder and/or iodine irrigation reduce infection after spine surgery. Linhares D, Pinto BS, Ribeiro da Silva M, Neves N, Fonseca JA. Orthosis in thoracolumbar fractures: a systematic review and meta-analysis of randomized controlled trials. Spine (Phila Pa 1976). 2020 Nov 15;45(22):E1523-31. Linhares et al. performed a systematic review and meta-analysis of the available literature comparing the use of orthoses with no immobilization in the management of acute stable thoracolumbar burst fractures. The authors found that, overall, there were no significant differences between the group receiving orthoses and the group with no immobilization with regard to pain scores or radiographic changes, and they recommended that conservative treatment of thoracolumbar burst fractures not include bracing. These findings confirm previous studies on the topic.