Full Endoscopic Piecemeal Resection of Lumbar Ligamentum Flavum Cyst With Uniaxial Large Working Channel Spinal Endoscope: Technical Report and Case Series

OBJECTIVES: Lumbar ligamentum flavum cyst is a rare degenerative disease of the spine, which remains poorly reported in the literature. Although full endoscopic surgery has been used for cyst resection, there is no well depicted and accepted technique so far. In this report, we introduce our preliminary experience of the surgical technique for piecemeal cyst resection with a uniaxial large working channel spinal endoscope, and provide the detailed description of endoscopic pathological anatomy. METHODS: This is a retrospective review of a predesigned three-step uniaxial full endoscopic surgical technique. The lumbar ligamentum flavum cysts were removed using a large working channel spinal endoscope. The spinal endoscopic database of the author's department was retrospectively reviewed for patients treated from February 2023 to December 2024. Patients diagnosed as lumbar ligamentum flavum cysts and treated with this technique were included for analysis. The basic information, complications and follow-up clinical outcome parameters (visual analogue scale, VAS, Oswestry Disability Index, ODI, modified MacNab criteria) were collected for evaluation (Shapiro-Wilk test, Wilcoxon's signed-rank test). RESULTS: Totally, seven patients with ligamentum flavum cyst were included for analysis. All the surgical procedures were successfully performed. The brownish-red soft jelly-like contents and serious adhesion between the ventral wall of the cyst and the dura were notable features of ligamentum flavum cyst. No intraoperative complications were found. The patients were followed up for at least 1 year. The clinical outcomes were satisfactory. Visual analogue scale and Oswestry Disability Index at all follow-up time points were significantly improved (p < 0.05). The excellent and good rate according to modified MacNab criteria was 100% at the last follow-up. CONCLUSION: Uniaxial large working channel spinal endoscopy is potentially a safe and effective choice in minimally invasive surgery to remove lumbar ligamentum flavum cyst.