Postoperative Longitudinal Outcomes in Patients with Residual Disc Fragments after Percutaneous Endoscopic Lumbar Discectomy

摘要

Background: Residual disc fragments are observed on immediate postoperativemagnetic resonance imaging (MRI) in 2.8–15% of patients after percutaneousendoscopic lumbar discectomy (PELD). Considering the known postoperativelongitudinal outcomes in patients with residual disc tissue, a ‘watchful waiting’strategy may be preferable to immediate re-operation in patients with asymptomaticresidual disc material.Objectives: The aim of the present study was to compare the longitudinal clinicaloutcomes between PELD patients in whom the complete removal of disc fragmentswas achieved (complete group) and those in whom residual disc fragments wereobserved on postoperative MRI (residual group).Study Design: Retrospective nested case-control study.Methods: A total of 225 patients were included (complete group, n=187 andresidual group, n=38). Clinical assessments were performed using the visual analogpain score for the leg (VAS-L, x/10) and back (VAS-B, x/10) and the Korean version ofthe Oswestry Disability Index (K-ODI, x/45). A linear mixed-effects model was usedto analyze changes during the first 24 postoperative months.Results: One month after surgery, significant improvements in the VAS-L, VAS-B andK-ODI values were observed and were maintained during the first 24 postoperativemonths. No differences in these changes were noted between the groups. Early reoperation (during the first 3 postoperative months) was performed in 3 patients inthe residual group (7.9%) and in 4 patients in the complete group (2.1%) (P = 0.10).Limitations: First, the study design was retrospective. Moreover, the number ofpatients was relatively small and therefore insufficient to achieve robust statisticalpower. Second, we did not explore the radiological outcomes in patients withasymptomatic residual disc material because follow-up MRI was only obtained todocument symptom recurrence.Conclusion: When residual disc tissue is observed in asymptomatic patients, a‘watchful waiting’ strategy may be preferable to immediate re-operation. However,an increased early re-operation rate is expected for patients with residual disc tissue.