Technique and outcomes of the trans-superior articular process approach for endoscopic thoracic discectomy

OBJECTIVE Transforaminal endoscopic thoracic discectomy (TETD) has been shown to lead to favorable outcomes in cases with symptomatic thoracic disc herniation (TDH). However, due to various anatomical constraints, developing a transforaminal corridor especially in the upper and middle thoracic spine is often difficult and foraminoplasty is required to gain access into the foramen. Conventional foraminoplasty with a bone reamer or endoscopic drill can be associated with inadvertent facet removal and increases the risk of injury to the neural tissue. The objective of this study was to describe the technique and outcomes of the trans-superior articular process (SAP) approach for endoscopic thoracic discectomy under local anesthesia for paramedian and central herniations. The trans-SAP approach involves making a pilot hole in the lateral part of the SAP with a Jamshidi needle followed by enlargement of the tract with manual side-cutting bone drills. This creates a trans-SAP corridor for insertion of the working cannula and endoscope to access the central and paracentral disc and perform adequate decompression. Although the trans-SAP approach is already being utilized for endoscopic lumbar discectomy and decompression, it has not been previously described for the thoracic spine. METHODS This was a retrospective review of prospectively collected data. Patients who underwent trans-SAP endoscopic thoracic discectomy for symptomatic TDH and had a minimum follow-up of 6 months were included. Outcome measures included patient-reported outcome measures (PROMs) (visual analog scale [VAS] and Oswestry Disability Index [ODI]) and complication rates. PROMs were analyzed at the preoperative and 1-month, 3-month, 6-month, and last postoperative follow-up timepoints. RESULTS Thirty-eight patients were included (mean age 48.9 years). Most disc herniations (55.3%) were central (63.1%) and located in the middle thoracic spine (55.3%). The mean operative time and hospital stay were 42 minutes and 1.3 days, respectively. The mean follow-up duration was 11.5 months. The mean VAS score significantly improved from 7.8 preoperatively to 3.5 at 1 month, 2.5 at 3 months, 2 at 6 months, and 1.5 at the latest follow-up (p < 0.001). The mean ODI score significantly improved from 68.3 preoperatively to 30.5 at 1 month, 22.1 at 3 months, 15.8 at 6 months, and 13.2 at the latest follow-up (p < 0.001). One patient (2.6%) had a complication (recurrent disc herniation). CONCLUSIONS Trans-SAP endoscopic thoracic discectomy can be a safe and effective surgical option for patients with symptomatic TDH.