Elsevier

World Neurosurgery

Volume 110, February 2018, Pages e504-e513
World Neurosurgery

Original Article
Posterior Lumbar Interbody Fusion with 3D-Navigation Guided Cortical Bone Trajectory Screws for L4/5 Degenerative Spondylolisthesis: 1-Year Clinical and Radiographic Outcomes

https://doi.org/10.1016/j.wneu.2017.11.034Get rights and content

Objective

We describe our technique and evaluate clinical and radiographic outcomes for patients undergoing L4/5 posterior lumbar interbody fusion with 3D-navigation guided cortical bone trajectory screws (PLIF-CBT) for grade 1 or 2 degenerative spondylolisthesis with a minimum follow-up time of 12 months.

Methods

A single-institution series of 18 patients was evaluated with data prospectively collected and retrospectively analyzed. Pain and disability scores were collected preoperatively and at a minimum of 12 months postoperatively, including back and bilateral leg pain visual analog scores (VAS) and Oswestry Disability Index (ODI) scores. Radiographic fusion was assessed as complete, partial, or none based on the presence of bridging bones across the disc space, posterior elements, or both.

Results

Patients demonstrated statistically significant reductions in back pain VAS (P = 0.0025), leg pain VAS (P < 0.0001), and ODI (P < 0.0001) at a minimum of 12 months postoperatively. Radiographic fusion at an average of 14.9 months postoperatively was available for 16/18 patients, with 6 patients demonstrating fusion (4/6 with complete fusion; 2/6 with partial fusion). There were no instances of intraoperative complications or delayed complications requiring subsequent interventions.

Conclusions

PLIF-CBT can be performed in a safe and reproducible fashion with excellent clinical outcomes at 1 year postoperatively. The outcomes did not correlate with fusion status, which was unexpectedly low at 37.5% without significant hardware abnormalities necessitating reoperations. PLIF-CBT offers several perioperative advantages compared with traditional open PLIF and requires longer-term studies to demonstrate its durability with regard to improvement in clinical pain and radiographic endpoints, including anterior and/or posterior element fusion.

Introduction

Spinal fusion for lumbar degenerative spondylolisthesis has demonstrated durable benefits with regard to patient-reported outcomes and healthcare cost-effectiveness standpoints.1, 2, 3, 4, 5 Affecting 6% of the population,6 this pathologic condition usually arises from a combination of degenerative disc disease, facet arthropathy, and pars interarticularis abnormalities. The combination of foraminal and central canal stenosis can lead to symptoms of radiculopathy and neurogenic claudication. Patients with significant symptoms in whom conservative management is unsuccessful, including physical therapy, oral medications, and epidural steroid injections, often meet the criteria for surgical intervention.

Anterior and lateral approaches for lumbar fusion have proved optimal in patients with certain anatomic and global alignment factors; however, the posterior approach remains the most commonly used and time-tested.7, 8, 9, 10, 11, 12 Ralph Cloward first described the posterior lumbar interbody fusion (PLIF) in 1944,13 and since then the procedure has gone through considerable variations in technique and technology. Traditionally, PLIF entails a wide laminectomy, bilateral total facetectomies, placement of bilateral interbody grafts, and pedicle screw and rod fixation.

Although the procedure is well tolerated in the majority of patients, it is not without a significant complication profile. Retraction of the neural elements required to place the interbody grafts can result in new neurologic dysfunction and cerebrospinal fluid leak in 7% to 10% of cases.14 Intraoperative blood loss can range from 400 to 800 mL, requiring blood transfusions in many cases, and average hospital stays are reported to be as long as 10 days in some studies.15, 16, 17 Hardware complications are rare, occurring in fewer than 2% of patients,14, 18 but they require revision surgeries that contribute to poorer patient satisfaction and increased healthcare costs.

To this end, minimally invasive strategies for PLIF have become of increasing interest to minimize blood loss, postoperative pain, hospital stays, and neurologic injuries while preserving low hardware complication rates. Cortical bone trajectory (CBT) screws were first described by Santoni et al.19 in 2009 as an alternative to traditional trajectory pedicle screws for PLIF. With a more inferomedial entry point and superolateral trajectory, this approach requires a smaller incision and less tissue dissection to place instrumentation. Owing to bicortical purchase, biomechanical tests in cadaveric models have shown CBT screws to have improved resistance to craniocaudal toggling, 30% increased uniaxial pullout strength, and 1.7 times higher torque in comparison with traditional trajectory pedicle screws.20, 21, 22 This technique can be performed with less thecal sac retraction to place narrower interbody cages; thus, facet resection, risk of neurologic injuries, and risk of durotomies are minimized.

The objectives of our study were 3-fold. First, to describe our surgical technique for L4/5 PLIF with CBT pedicle screws (PLIF-CBT) in a reproducible fashion with minimal perioperative complications. Second, to demonstrate the utility of intraoperative CT (iCT) and 3D-navigation guidance for this alternative screw trajectory technique. Third, to determine the clinical and radiographic outcomes of PLIF-CBT at a minimum of 1 year postoperatively at our institution in comparison with recent published reports and historical cohorts of open PLIF with traditional pedicle screw instrumentation.

Section snippets

Data Collection

Between February 2015 and May 2016, patients undergoing L4/5 PLIF-CBT were prospectively enrolled in this study. Surgical indications included L4/5 degenerative spondylolisthesis with symptoms of neurogenic claudication, radicular pain refractory to conservative management, or both for at least 6 months. Twelve patients had Meyerding grade 1 spondylolisthesis, and 6 patients had Meyerding grade 2 spondylolisthesis. Patients with instability related to trauma, tumor, or infection and those who

Demographic and Perioperative Outcomes

A total of 18 patients met inclusion criteria, of whom 13 were women. The average age at the time of surgery was 67.2 years (range, 52–79 years), and the average BMI was 28.9 kg/m2 (range, 20.6–40.5 kg/m2). There were no instances of intraoperative complications including neurologic injury, durotomy, vertebral body fracture, malpositioned screws, or pedicle/endplate fracture. Average blood loss and operative time were 161.67 mL and 219.67 minutes, respectively. No patient required

Discussion

The current report summarizes our single-institution experience of 18 patients undergoing PLIF-CBT for grades 1 and 2 L4/5 degenerative spondylolisthesis. We demonstrate our technique using 3D navigation-guided iCT technology, which was performed in a reproducible manner with no intraoperative complications. At their 1-year follow-up visits, patients demonstrated statistically significant reductions in back pain VAS, leg pain VAS, and ODI scores. Fusion rates at an average of 14.9 months

Conclusions

Our study demonstrates that PLIF-CBT can be performed safely and reproducibly using iCT-based 3D-navigation image guidance with grades 1 or 2 L4/5 degenerative spondylolisthesis. The low complication profile while decreasing intraoperative blood loss and hospital length of stays reveals this procedure to be superior to traditional PLIF. Our clinical outcomes demonstrate that 1 year after surgery, patients experienced significant reductions in back pain, leg pain, and disability, and none

Acknowledgments

The authors thank Edward Butler and Trishana Ashman for assistance with clinical and radiographic data collection.

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    Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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