Microendoscopic decompression for lumbar spinal stenosis caused by facet-joint cysts: a novel technique with a cyst-dyeing protocol and cohort comparison study.

Objective Facet cysts may represent a sign of intrinsic facet disease and instability, increasing the importance of less-invasive approaches that limit tissue dissection and improve visualization. The authors developed an intraoperative cyst-dyeing technique, involving the injection of indigo carmine from the facet joint into the cyst, as an adjunct during decompression. This study aimed to evaluate the clinical outcomes and perioperative complication rates of microendoscopic spinal decompression for lumbar spinal stenosis (LSS) and lumbar foraminal stenosis (LFS), caused by facet cysts and to elucidate the efficacy of the cyst-dyeing method in microendoscopic surgery for facet cysts. Methods Forty-eight consecutive patients who underwent surgical treatment with microendoscopic decompression for symptomatic LSS or LFS caused by facet cysts from 2011 to 2018 were reviewed. These patients were divided into two groups: a group that did not receive dye (N), with the patients undergoing surgery from April 2011 to May 2015; and a group that received dye (D), with patients undergoing surgery from June 2015 to March 2018. The authors evaluated the operative time, blood loss, perioperative complications, visual analog scale scores for low-back and leg pain, and Japanese Orthopaedic Association scores. Surgical outcome was evaluated 2 years postoperatively and was compared between groups D and N. Results The clinical outcomes were generally excellent or good. Group N consisted of 36 patients and group D of 12 patients. Comparing the clinical results, it was found that the cyst-dyeing method reduced the perioperative complication rate, including reduction in dural tears to 0%, and shortened the average operative time by approximately 40 minutes. Conclusions In this study, the authors demonstrated that the clinical outcomes of microendoscopic spinal decompression in patients with LSS or LFS caused by facet-joint cysts are generally favorable. Additionally, the adjunctive cyst-dyeing method effectively delineated the cystic and dural boundaries, facilitating safer and more effective cyst separation and neural decompression. Microendoscopic surgery combined with this novel facet cyst-dyeing method is a safe and effective minimally invasive technique for facet-joint cysts.