Lumbar spinous process-splitting technique for ligamentum flavum cyst removal: the first use in Europe.

Background Laminotomy for lumbar stenosis is a well-defined procedure and represents a routine in every neurosurgical department. It is a common experience that the mono- or bilateral paraspinal muscles detachment together with supra and interspinous ligaments injury can lead to postoperative pain. In literature has been reported the application at the level of the lumbar spine of a minimally invasive technique defined as lumbar spinous process-splitting technique (LSPST). Methods In the current study, we present a case series of 12 patients that underwent LSPSL from September 2019 to April 2020. Two patient suffering from ligamentum flavum cyst, 8 patients with single level lumbar canal stenosis (LCS) and two patients with two-level LCS. The approach was mini-open, with reduced soft tissue dissection and without paraspinal muscles injury. Moreover, a novel morphological classification of postoperative muscle atrophy is proposed as well as a volumetric analysis of the decompression achieved. Conclusion At our knowledge, this is the first description of this surgical technique and the first LSPSL case series in Europe. Furthermore, cases of ligamentum flavum cyst removal using this safe and effective technique are not yet reported. Abbreviations Lumbar canal stenosis (LCS), lumbar spinous process-splitting technique (LSPST), minimally invasive spine surgery (MISS)

A FINITE ELEMENT MODEL FOR COMPRESSIVE ICE LOADS BASED ON A MOHR-COULOMB MATERIAL AND THE NODE SPLITTING TECHNIQUE

This paper presents a finite element model for the simulation of ice-structure interaction problems, which are dominated by crushing. The failure mode of ice depends significantly on the strain rate. At low strain rates the ice behaves ductile, whereas at high strain rates ice reacts in brittle mode. This paper focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of numerical approaches for the simulation of ice can be found in the literature. Nevertheless, the literature approaches do not seem suitable for the simulation of continuous ice-structure interaction processes at low and high confinement ratios in brittle mode. Therefore, this paper seeks to simulate the ice-structure interaction with the finite element method (FEM). The objective of the here introduced Mohr-Coulomb Nodal Split (MCNS) model is to represent the essential material behavior of ice in an efficient formulation. To preserve mass and energy as much as possible, the node splitting technique is applied, instead of the frequently used element erosion technique. The intention of the presented model is not to reproduce individual cracks with high accuracy, because this is not possible with a reasonable element size, due to the large number of crack fronts forming during the ice-structure interaction process. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with ice-extrusion and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental values.

Minimally Invasive Posterior Cervical Discectomy: 2-Dimensional Operative Video

Minimally invasive posterior cervical microdiscectomy is an appropriate surgical approach for patients with foraminal stenosis from herniated disc with radicular symptoms that is not responsive to conservative management. While anterior cervical discectomy and fusion (ACDF) or arthroplasty is increasingly utilized to treat herniated disc, a posterior approach eliminates the risk of potential approach related injuries to the esophagus, carotid artery, or recurrent laryngeal nerve. Additional benefits of posterior decompression include avoidance of instrumentation, which represents an increased healthcare cost, as well as potential long-term risks of adjacent-level pathologies or device failures. A traditional open posterior cervical approach has the potential to cause significant postoperative pain due to dissection of the paraspinal musculature and the potential for disrupting the posterior tension band with inadvertent injury to the interspinous ligaments. Such disadvantages are reduced by utilizing the minimally invasive technique where a small tubular working channel is placed through a muscle splitting technique via a paramedian approach. This technique minimizes the need for muscle stripping, and thus decreases postoperative functional and structural disturbance. Discectomy in this case can also be safely performed with minimal retraction at the axilla of the nerve root. Additionally, this approach can be utilized in an ambulatory setting, which coupled with the lack of any additional instrumentation helps contribute to the overall healthcare cost savings of such a procedure. This video describes how the minimally invasive posterior cervical discectomy can be effectively and safely performed in this illustrative case. The patient consented to the procedure and publication.

Dural splitting reconstruction in retethering after lipomeningocele repair: Technical note

Background: Tethered spinal cord syndrome (TCS) can occur after the surgical repair of lipomeningoceles (LMCs). In these cases, the tethering results from postoperative adhesions between the spinal cord and the overlying repaired dura. A watertight dural closure using the residual dura and/or the surrounding tissues does not always provide enough space for the spinal cord and risks retethering. Here, we report a 16-year-old patient with secondary TCS following lipomeningocele repair who successfully underwent release of the tethered filum terminale utilizing a novel dural splitting reconstructive technique to attain a water-tight closure without the need for a duroplasty. Methods: A 16-year-old patient had a LMC repaired at birth. She now presented with progressive low back pain, and gait disturbances. The MRI documented secondary spinal cord tethering at the prior spinal dysraphism repair site. Results: A secondary release of the filum terminale utilizing a novel dural splitting technique to avoid the need for a duroplasty was performed. Conclusion: Here, in a 16-year-old patient with a recurrent tethered cord syndrome following repair of a LMC at birth, we utilized a novel dural splitting reconstruction technique and averted the need for a duroplasty.