Postlaminectomy synovial cyst formation: a possible consequence of ligamentum flavum excision

Ligamentum flavum is generally resected with impunity when a laminectomy is performed; it is a strong ligament and its removal may not be inconsequential. We sought to examine the consequence of resection of ligamentum flavum as it pertains to the formation of synovial cysts. Following IRB approval, we retrospectively reviewed the charts of consecutive patients who underwent a laminectomy for any diagnosis during the years 2009-2010. Exclusions were made for patients undergoing resection of a synovial cyst, laminectomy done as part of a fusion, and microdiscectomy. A total of 201 laminectomies were performed. 10 instances of post-laminectomy synovial cyst occurred in only the lumbar spine. Synovial cysts occurred exclusively after surgery for stenosis (n=10). Laminectomy and resection of the ligament flavum is a risk factor for the subsequent formation of a synovial cyst. Secondary synovial cyst formation should be suspected in individuals who develop radiculopathy after laminectomy for stenosis.