Full-Endoscopic Decompression for Thoracic Ossification of the Ligamentum Flavum Combined with Dural Ossification

Summary

We describe a minimally invasive surgery using a full-endoscopy system for the single segmental thoracic ossification of the ligamentum flavum, combined with dural ossification, at Hebei General Hospital.

Abstract

Ossification of the ligamentum flavum (OLF) can result in spinal stenosis. Thoracic spinal cord compression due to spinal stenosis is a common cause of progressive thoracic myelopathy in Asian countries. The incidence of complications is high in open decompression surgeries for thoracic OLF. With dural ossification (DO), the risk of complications is even higher in thoracic OLF. We introduce a full-endoscopic decompression surgery for thoracic OLF combined with DO under local anesthesia. Hemilaminectomy is performed using a high-speed burr under the endoscopy first, and then decompression of the contralateral spinal canal is completed using an "over the top" technique. DO resection uses the eggshell technique; after the base of the DO is cut from the lamina, forceps or lamina rongeurs are typically used for removal. The dural defect left after resection does not need repair. Neurological function was improved, and no complications such as hematoma or neck pain occurred. On imaging, no pseudodural cyst, cerebrospinal fluid leakage, or wound complications were observed after the operation. Endoscopic surgery causes less damage to the posterior ligament complex, so no cases of persistent back pain complaints or secondary internal fixation requirements were found in this study. Full-endoscopic decompression can achieve good imaging and clinical effects in the treatment of thoracic OLF with DO.

Introduction

Ossification of the ligamentum flavum (OLF) is one of the most common causes of thoracic myelopathy or radiculopathy in Asian countries, especially in Japan^1,2. The prevalence has been reported to vary from 3.8% to 26% in East Asia^1,3,4. Posterior decompression is recommended for the treatment of thoracic OLF according to the compression location and its aetiologies⁵. Dural ossification (DO) is a difficult problem in surgical procedures⁶; when the dura mater is ossified,....

Protocol

This study was approved by the Ethics Committee of Hebei General Hospital. Informed consent was obtained from all individual participants.

1. Preoperative preparation

1. Have the patient simulate the operation position. Have the patient lay in the prone position on the sickbed 3-5 days before the operation. Cushion the thorax and ilium with soft pillows.
2. Plan the operation on the picture archiving and communication system (PACS). Measure the thickness of the lamina and OLF on the computerized tomography (CT) and magnetic resonance imaging (MRI) scans, so that the depth of the bone window is roughly sized.....

Results

From June 2017 to December 2020, full-endoscopic decompression surgeries were performed on four patients in our hospital, including one male and three females aged 46-72 years with an average age of 64.3 years. The average operation time was 185.3 min. The mean follow-up was 16 months. Patients experienced relief of their myelopathy symptoms. The modified Japanese Orthopedic Association (mJOA) score improved at the last follow-up. The Patient Satisfaction Index (PSI)¹⁴ at the last follow-up was 75.......

Discussion

Although endoscopic thoracic surgery has achieved satisfactory clinical outcomes^10,15,16, there are still debates on some operation details, such as the operation sequence, surgical instruments, and decompression skills. The operation sequence and the resection of the DO are the key steps of the surgery. Some surgeons prefer to perform contralateral decompression first and then remove the ipsilateral ossification

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Picture Archiving and Communication System (PACS)	Neusoft Co., Ltd.	Neusoft PACS	Image requirement: DICOM; Running system: Windows 7 or Windows 10
Endoscope system	SPINENDOS GmbH	SP081430.030	Inner diameter:4.3mm; Outer diameter:7.0mm; Field angle: 80 °; Visual angle: 30 °; Working length: 181 mm.
Working sheath	SPINENDOS GmbH	SP082615.265	Φ7.2mm×178mm
Puncture needle	SPINENDOS GmbH	SP082016.150	1.6mm×150mm
Guide rod	SPINENDOS GmbH	SP082616.300	Φ7.0mm×225mm
Endoscopic rongeur	SPINENDOS GmbH	SP082700.040L	Φ4.0mm×360mm
Bipolar electrocoagulation probe	ELLIQUENCE	DTF-40	40cm
Endoscopic forceps	SPINENDOS GmbH	SP082781.835	Φ2.5mm×330mm
Endoscopic hook	SPINENDOS GmbH	SP082628.351	Φ2.5mm×310mm
High-speed burr	XIYI	MQZ	Φ3.2mm×328mm