Symptomatic Residual Bone Fragment of the Superior Articular Process After Percutaneous Transforaminal Endoscopic Discectomy

Abstract Purpose: To demonstrate the clinical characteristics of symptomatic residual bone fragment of the superior articular process (symptomatic-RBF-SAP) after percutaneous transforaminal endoscopic discectomy (PTED), and to discuss its types and revision strategies. Methods: We retrospectively analyzed 556 consecutive patients who underwent PTED between July 2015 and November 2017; seven (1.2%) of whom experienced symptomatic RBF-SAP. Clinical outcomes were evaluated using the visual analog scale (VAS), Oswestry disability index (ODI), and modified MacNab criteria. Results: Intractable radicular leg pain was the most common symptom. Symptoms occurred late in 2 patients (>3 days) and early (<3 days) in five patients. Symptoms occurred on the contralateral side in two early cases. Cerebrospinal fluid (CSF) leakage and nerve injury were secondary complications in one early case. CSF leakage also occurred in one delayed case. Patients with radicular leg pain underwent secondary repair surgery. The mean follow-up period was 17.7 months, VAS of radicular leg pain improved from 8.7 to 1.8, and ODI improved from 74.5% to 23.9%. The final outcomes were excellent, good, and fair in one, three, and two patients, respectively. Conclusions: Foraminoplasty for PTED may increase the risk of symptomatic-RBF-SAP. If this occurs, revision surgery is required, not only for severe pain, but also for secondary complications that may occur.