Introduction: Not only decompression but also fusion are often required in the surgical treatment of lumbar diseases with instability, such as lumbar degenerative spondylolisthesis and spondylolytic spondylolisthesis. In the lumbar spine, approximately 80% of the load is shared by the anterior strut, so it is undeniably important to reconstruct the anterior strut when performing fusion surgery. Since 2022, we have been performing micro-endoscopic lumbar interbody fusion (MELIF) with PPS for minimally invasive surgery.

Methods: The operation was enforced in 41 cases and 48 disc-levels. There were 19 men and 22 women with a mean age of 67 years. L3/4 intervertebral space was fixed in 4 cases, L4/5; 34 cases, L4/S; 1 case, L5/S; 5 cases. Under the micro-endoscope, the superior articular process was partially resected, and the intervertebral disc was dissected as widely as possible via the Kambin’s triangle. And two Trabecular Metal (TM) cages were inserted with the autologous iliac bone graft. Finally, PPS fixation was performed.

Results: The operative time per 1 intervertebral space was 101.3 minutes and the blood loss was 60.4 ml. Of the 48 intervertebral spaces, 2 TM cages were inserted in 47 intervertebral spaces. The mean JOA score of the cases followed up over 6 months was 13.3 before the operation and 27.2 after the operation, and the mean improvement rate was 86.2 %. Complications included deep wound infection, anterior partial cage prolapse, posterior partial cage prolapse and exiting nerve root irritation in one patient each. The case in which the irritation symptom of the exiting nerve root appeared improved with time.

Discussion: MELIF surgery is a very useful procedure because it is minimally invasive and can achieve strong interbody fusion. Comparing the conventional LIF procedures; PLIF and TLIF, the surgical time was shortened, and the blood loss was less. However, the procedure must be completed with the limited field of view and narrow working space of the endoscope, which requires unique manipulation and attention.