Angular-Laminar Access in Minimally Invasive Portal Surgery of the Lumbar Spine Improves Exposure and Surgical Operability

Background: The introduction of minimally invasive techniques in lumbar stenosis has had a significant impact in terms of reducing perioperative morbidity and the incidence of iatrogenic instability. According to the principle of keyhole surgery, minor variations in technique can result in significant variations in surgical outcomes. Aims: A comparative anatomical study was conducted to assess the impact of an innovative, more lateral entry point (angular-laminar access, ALA) on surgical maneuverability during minimally invasive circumferential microdecompression using a crossover technique. Methods: The anthropometric measurements were acquired on preoperative baseline CT images. A comparative study was conducted between the standard technique (marginal-laminar access, MLA) and the present one, applying the operability score (OS) principles. An illustrative case is reported to demonstrate the feasibility of the technique. Results: The ALA was found to increase maneuverability area (MA), maneuverability arc (MAC), and surgical angle of attack (SAA), reducing the conizing effect of the portal system, with a non-significant increase in the depth of the surgical field (D). The direction of the surgical corridor allows for better control over the contralateral recess, the increased range of motion (ROM) of the system optimizes visibility of potential blind corners. Conclusion: The ALA provides improved operability and surgical exposure in minimally invasive microdecompression using the crossover technique.