Percutaneous endoscopic interlaminar discectomy via inner border of inferior pedicle approach for downmigrated disc herniation: a retrospective study

OBJECTIVE: To evaluate the efficacy and feasibility of percutaneous endoscopic interlaminar discectomy (PEID) via the inner border of the inferior pedicle approach for downmigrated disc herniation. METHODS: Seventeen patients who had downmigrated disc herniation were included in this study from May 2020 to February 2021. After PEID via the inner border of the inferior pedicle approach, a retrospective study was conducted on all patients. Radiologic findings were investigated, and based on the level of migration seen on preoperative magnetic resonance imaging (MRI), participants were divided into two types (high-grade and low-grade migrations). Preoperative, 1st post-operative day, 3rd post-operative month, and the final follow-up visual analogue scale (VAS) assessments for back and leg pain and preoperative, 3rd post-operative month, and the final follow-up Oswestry disability index (ODI) evaluations were performed. The clinical effects at the final follow-up were assessed by the modified MacNab criterion. RESULTS: All patients successfully completed surgery. There were 10 males and 7 females in the group. These patients were 42 years old on average (range, 25–68 years). Four and 13 patients had downmigrated disc herniation with high-grade and low-grade, respectively, on MRI. The mean follow-up duration was 10.47 ± 1.84 months (range, 8–14 months). The mean VAS score for back and leg improved from 5.18 ± 0.81 preoperatively to 1.35 ± 0.49 at the final follow-up (P < 0.05) and 6.94 ± 0.66 preoperatively to 1.47 ± 0.51 at the final follow-up (P < 0.05), respectively. The mean ODI score improved from 48.00 ± 3.64 preoperatively to 18.71 ± 1.31 at the final follow-up (P < 0.05). According to the modified MacNab criterion, 15 patients (88.2%) obtained excellent, while the rest 2 patients (11.8%) reported good outcomes. CONCLUSION: PEID via the inner border of the inferior pedicle approach could be a good alternative option for the treatment of downmigrated disc herniation.