摘要Objective To report a case of far-lateral lumbar disc herniation with a huge upward-migrated free fragment treated with a novel transforaminal endoscopic approach,and summarize the treatment experience.Methods A 59-year-old male patient with far-lateral lumbar disc herniation(L3-4,right side,migrated free type)was admitted in December 2021.Percutaneous transforaminal endoscopic discectomy(PTED)was performed under local anesthesia on December 14,2021.However,the procedure was aborted due to technical challenges caused by the upward-migrated free nucleus pulposus compressing the exiting nerve root downward into the intervertebral foramen,resulting in an extremely narrow Kambin's triangle.After the patient declined open surgery,we adjusted the puncture trajectory through the same incision,targeting the anterosuperior corner of the intervertebral foramen to establish the working channel,and successfully removed the large free nucleus pulposus.Results The postoperative follow-up time was 3 years.Complete leg pain relief and ambulation were achieved on postoperative day 1.MRI on postoperative day 3 showed complete removal of the migrated free nucleus pulposus with sufficient neural decompression.Final follow-up outcomes were excellent based on the modified MacNab criteria.Conclusions It is difficult to perform PTED with Kambin's triangle approach for far-lateral lumbar disc herniation with upward-migrated free fragments compressing the exiting root downward into the intervertebral foramen.Targeting the anterosuperior corner of the intervertebral foramen to establish the working channel offers a simple and feasible alternative for effective fragment removal.