A Novel Transforaminal Approach for Upmigrated Lumbar Disc Herniations in the Hidden Zone of MacNab: A Surgical Technical Note

Abstract

Objective: Transforaminal percutaneous endoscopic discectomy (TPED) is a minimally invasive surgical procedure used to treat herniated disc fragments in the hidden zone of MacNab. This study aimed to investigate the efficacy, advantages, and safety of TPED for superiorly migrated lumbar disc herniation in the hidden zone of MacNab, focusing on patients with isolated causative factors such as prolapsed discs.Methods: A cohort of patients with clinical conditions involving isolated causative factors of herniated discs in the hidden zone of MacNab were selected for TPED. Patients with conditions contributing to clinical symptoms were excluded. Twelve patients with hidden-zone disc herniations underwent TPED. Under fluoroscopic guidance, precise skin markings were performed, followed by chromodiscography and epidurography. A nonstandard floating approach was utilized for TPED. The assessment of patients included visual analogue scale and Oswestry Disability Index scores. The outcomes were evaluated based on the modified MacNab criteria after 12 months.Results: Successful removal of the herniated fragments was achieved in all 12 cases of hidden-zone disc herniations that underwent TPED. According to the modified MacNab criteria, 11 out of 12 patients achieved excellent outcomes, while one patient attained a good outcome.Conclusions: The transforaminal approach in TPED was confirmed to be a highly effective and minimally invasive technique for managing hidden-zone disc herniations. The procedure yielded satisfactory to excellent results, accompanied by a significantly shorter rehabilitation period and minimal blood loss. Importantly, the pars interarticularis and lamina remain fully intact with the transforaminal approach.