The Impact of Epidural Fat Resection on Postoperative Outcomes in Posterior Surgery of Lumbar Spine

Study Overview
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Brief Summary
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Posterior lumbar epidural fat commonly had been considered a simple space-filling tissue. Anatomic studies on posterior epidural space and its contents are few, including semifluid property. In other words, there has not been studied thoroughly regarding the significance and role of posterior epidural fat in lumbar spine. In adults, epidural fat situated in the posterior triangle limited by the lamina, the ligamentum flavum, and the posterior surface of thecal sac. The fat tissue was covered by a thin membrane of connective tissue, which were free under this layer. The anterior surface of this membrane lay close to the dura mater without any attachment. To date, the epidural fat has been resected routinely by pituitary forcep and suction drainage during posterior lumbar surgery. However, the investigators focused on the role of epidural fat, which might be associated with postoperative outcome. The investigators thought that this peculiar character, epidural fat, should be caused by certain etiologies. In general, each tissue, such as epidural fat, has its inherited features and significance, thereby the epidural fat has also specific role. However, there has not been fully studies regarding it. Thus, the investigators aimed to evaluate the impact of the posterior epidural fat on the postoperative outcomes such as pain intensity and functional outcomes by whether the epidural fat would be resected or not during posterior decompressive surgery. The investigators hypothesized that the epidural fat would be associated with postoperative pain intensitive, functional outcomes, and complications of the surgery such as failed back surgery syndrome. In this study, new device for resection of epidural fat was not utilized, but just resected with conventional devices such as pituitary forcep.

Conditions
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Spinal Stenosis

Intervention / Treatment
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* Procedure: Resection of epidural fat
* Procedure: No resection of epidural fat


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients with a lumbar spinal stenosis, which were diagnosed using lumbar spine radiographs and magnetic resonance images (MRI) that corresponded to clinical manifestations and physical examinations patients who underwent one-level posterior decompression patients aging between 20 and 80 years patients who volunteered for this study with written consent patient who were followed-up for one year or more Exclusion Criteria: fractures, infection, or tumors in the lumbar spine patients with hemorrhagic disorders such as hemophilia and thrombocythemia patient with a follow-up period of less than one year patients who are not suitable for this study judged by the principal investigator

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Resection of epidural fat<br>During surgical procedure, epidural fat was resected fully. | Procedure: Resection of epidural fat<br>* During surgical procedure, the epidural fat with pituitary forcep and rongeur was resected.<br>|
| Active Comparator: No resection of epidural fat<br>During surgical procedure, the epidural fat was not resected. | Procedure: No resection of epidural fat<br>* During surgical procedure, the epidural fat with pituitary forcep and rongeur was not resected.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain score on the VAS | Pain intensity at lower back and radiating pain on the lower extremity were separately recorded at postoperative 1 month using visual analogue scale (VAS). | Postoperative 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Functional outcomes with Oswestry disability index (ODI) and SF-12 | Functional outcome was assessed using ODI and SF-12 at the follow-up times. | postoperative 3 and 12 months | 
| The extent of epidural fibrosis | the extent of epidural fibrosis was measured with the angle of leg raise at the postoperative 1 month. | Postoperative 1 month | 
| The change at postoperative enhanced MRI | epidural inflammation and postoperative change at the posterior epidural area of the affected segment was evaluated by postoperative enhanced L-spine MRI. | 3, 12 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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epidural fat, resection, spinal stenosis, lumbar spine