Transpars approach for L5-S1 foraminal and extra-foraminal lumbar disc herniations: technical note

BACKGROUND: The short pars and the narrowed surgical corridor for far lateral L5S1 herniation make the transpars approach challenging. The aim of this study is to determine the feasibility, efficacy, and safety of the transpars microscopic approach for the treatment of L5-S1 foraminal and extraforaminal lumbar disc herniation.METHODS: From 2015 to 2019, patients with L5-S1 far lateral lumbar disc herniation were prospectively recruited. Drug intake, working days lost, NRS-leg, NRS-back, nerve-root palsy, Oswestry disability-index, Macnab criteria were recorded before surgery and at follow-up. Patients were seen at 1-6-12 months after surgery. Lumbar dynamic X-rays were performed at 6-12 months after surgery and again at 2-4 years after surgery. Key-steps of surgery are described. RESULTS: Fourteen patients were enrolled. NRS-leg and NRS-back scores significantly improved (from 7.93 to 1.43 and from 3.2 to 0.6, respectively; P<0.0001). Oswestry Score significantly decreased (from 63.14 to 19.36 at 12 months; P<0.0001). L5 Root palsy improved in all cases (from 3.72/5 to 5/5; P<0.0001). At 12-months, excellent or good outcome (Macnab criteria) was achieved in 12 (85.7%) and 2 (14.3%) patients, respectively. All patients who were not retired returned to work within 30 days after surgery. No recurrence, instability or re-operations occurred.CONCLUSIONS: The trans pars microscopic approach is feasible, safe, and effective for L5-S1 foraminal and extraforaminal disc herniation. During surgery, the key-point is the oblique working angle, directed caudally, parallel to L5 pedicle. The iliac crest does not seem to constitute an obstacle.