Five-year clinical outcomes with endoscopic transforaminal outside-in foraminoplasty techniques for symptomatic degenerative conditions of the lumbar spine

Kai-Uwe Lewandrowski, Nicholas A. Ransom


Background: Lumbar foraminal stenosis in the extraforaminal zone is best directly visualized with the outside-in transforaminal endoscopic technique. Stenosis in that area is often missed with traditional translaminar surgery. The authors analyzed the long-term 5-year clinical results, reoperation rates, and unintended after care with the outside-in endoscopic transforaminal foraminoplasty for symptoms from lumbar foraminal stenosis to better establish clinical indications and prognosticators of favorable outcomes.
Methods: Long-term 5-year Macnab outcomes, visual analog scale (VAS) scores, complications, and unintended aftercare were analyzed in a series of 90 patients treated with the transforaminal outside-in selective endoscopic discectomy (SED™) with foraminoplasty for foraminal and lateral recess stenosis.
Results: At minimum 5-year follow-up, excellent results according to the Macnab criteria were obtained in 61 (67.8%) patients, good in 23 (25.6%), fair in 6 (6.7%), respectively. The mean preoperative VAS 7.55. The mean postoperative VAS was 2.87 and at last follow-up 2.53. Both postoperative VAS and last follow-up VAS were statistically reduced at a significance level of P<0.0001. Postoperative dysesthesia occurred in 8 patients (8.9%). While most of the 32 follow-up surgeries following SED™ were additional endoscopic decompressions and rhizotomies (24/32; 75%) were non-fusion procedures, only 8 of the whole study series of 90 patients (8.9%) underwent fusion at the index SED™ level within the minimum 5-year follow-up period. One patient opted for an open laminectomy (1.1%).
Conclusions: Patients with symptomatic foraminal stenosis may be treated successfully in a staged manner with outside-in transforaminal endoscopic decompression while maintaining favorable long-term outcomes without the excessive need for fusion in the vast majority of patients. The reoperation fusion rate at 5-year follow-up was approximately 3 times lower when compared to recently reported reoperation rates following traditional translaminar decompression/fusion.