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SLIP II Registry: Spinal Laminectomy Versus Instrumented Pedicle Screw Fusion

Aim: To conduct a randomized control trial comparing patient outcomes and satisfaction with or without expert panel review before making a final decision about surgery for grade I degenerative lumbar spondylolisthesis. A prospective, multi-center registry aimed at addressing important issues pertaining to outcomes from treatment for degenerative spondylolisthesis and spinal stenosis will be generated.

Background: Surgery may be offered to patients with symptomatic lumbar stenosis with degenerative lumbar spondylolisthesis who fail nonoperative treatment measures including physical therapy and epidural steroid injections. For patients with lumbar stenosis without spondylolisthesis, a decompression alone is typical, while those patients who do have degenerative spondylolisthesis and who also have significant mechanical back pain may be offered lumbar decompression with or without fusion. These guidelines were written based upon the SPORT study, which provided the highest quality of evidence available at the time. Additional studies have show that costly interventions such as lumbar fusion may ultimately be cost-effective if they provide durable clinical benefit. Two recent publications in The New England Journal of Medicine present new evidence with conflicting results on superficial review. The Spinal Laminectomy versus Instrumented Pedicle Screw (SLIP) trial provides level I evidence for the efficacy of fusion to improve clinical outcomes and lower reoperation rates compared to a standard laminectomy and medial facetectomy over a four year time frame in patients with neurogenic claudication associated with stable single level spondylolisthesis. Conversely, the Swedish study provides level II evidence that the addition of a variety of fusion techniques does not have significant benefit in the first two years following operation compared to a variety of decompression techniques in a heterogeneous population of patients with stenosis associated with spondylolisthesis. The patient populations treated, surgical techniques used, and outcome measures assessed differed between the two studies and when taken together, underline the need to new comparative effectiveness data for patients with this problem.

Additionally, one key challenge surgeons face is whether or not to recommend a spinal fusion. Spinal fusion is expensive, assoicated with greater costs and complications, but it appears to be necessary in at least 30% of patients.3 Preliminary data suggests that when when greater than 80% of an expert panel votes for one treatment opition, either a fusion or decompression alone, and when a patient's actual treatment aligns with the expert panel recommention, the patient-reported outcomes are greater than when the surgical approach is not aligned with the expert panel.10 This data highlights an interest in developing articifical intelligence (AI) that may be able to aid in both identification and predictive tasks. Any progress in this realm would be enormously powerful from a clinical standpoint and would likely result in more efficient use of surgical appraoches and in turn, healthcare spending.

All images that are captured in the registry will be used to train convolutional neural networks (CNN). These are mathematical operations which extract patterns from image data and generalize it across many images fed into the dataset. They primarily use calculations to extract patterns which are stored as a model which will be a collection of numbers. The images stored in this registry will be used to develop algorithms to assess cases in which an expert panel is more likely to suggest one treatment over the other as well as develop an algorithm that would prospectively classify patients as either 'stable' or 'unstable.'

Plan: Before making a decision regarding which specific operation should be performed in each case, each patient will be randomized to receive an expert panel review or to not receive an expert panel review. For patients who receive an expert panel review, the patients' de-identified lumbar MRI (sagittal and key axial images), 36-inch standing plain radiographs (if available), and flexion and extension radiographs will be uploaded into a web-based platform and reviewed with plans to share the reviews with patients and their treating physicians in real time. For patients who are randomized to no expert panel review, they will discuss with their surgeon the best surgical option for them and proceed as they would in standard of care. Patients with symptomatic lumbar spinal stenosis and single level degenerative grade I spondylolisthesis will be treated either with decompression or decompression with fusion. Symptomatic spinal stenosis will be defined as radicular and/or back pain either induced by or aggravated by activity and relieved by rest in a patient with either moderately severe or severe lumbar spinal stenosis. Patient-reported outcomes will be captured at baseline, at 3 and 6 months, and annually out to five years.

The imaging data will be used to create artificial intelligence (AI) algorithms that will help assess when an expert panel is more likely to suggest one treatment over the other as well as develop an algorithm that would prospectively classify patients as either 'stable' or 'unstable.' Ultimately long term follow-up will help confirm whether a case was correctly assessed as stable or unstable. A patient would be confirmed as unstable, if they underwent decompression alone and then required a re-operation to stabilize the spine at the level of spondylolisthesis within 5 years of the initial operation. In a similar way, a patient would be confirmed as stable, if no re-operation were necessary over the 5-year study follow-up period.

Interim Analysis: An interim analysis is planned when 150 patients have reached eligibility at 6 month follow-up. Patients' change from baseline patient-reported outcome questionnaires will be assessed.