Anterior spinal fusion has become a great minimal invasive procedure in degenerative lumbar spondylolisthesis patients. We have performed mini-open anterior lumbar interbody fusion (mini-ALIF). Furthermore, we used anterior interbody fusion cage and screw fixation and we could modify this mini-ALIF to less invasive manner. In this study, we reviewed the surgical outcomes of these anterior procedures.
Materials & Methods
143 patients with a minimum 2 years follow-up were enrolled in this study. At the beginning, we needed additional posterior fixation to prevent bone collapse in 54 patients (Group A: anterior and posterior surgery). 114 patients underwent only anterior surgery with the anterior cage (Group B). We evaluated degenerative changes and dynamic factors. Clinical results were estimated by Japanese Orthopaedic Surgery Association (JOA) score and low back pain status.
We also investigated long follow-up clinical data (> 5years) in 29 Group A and 81 Group B cases (ave. 9.5 years follow-up). We further surveyed salvage surgical cases with regard to their pathology.
Results
At first this single anterior procedure made mini-ALIF less invasive manner. The average operation time was 211 minutes in Group A and 95 minutes in Group B. The blood loss was 251 ml vs. 90 ml.
Clinical improvement was reliable in both groups. Satisfactory results were achieved in most Group A cases. JOA score showed their favorite conditions (pre-Op: 14.0, post-Op: 22.5, 2years: 24.2/29). In Group B, most patients were free from back pain and returned to daily life. The average JOA score was 17.3/29 at pre-op., 21.2 at post-op. and 25.3 at two years. The minor complaint like dullness at their back was less compared to Group A.
During long-term follow-up (more than 5 years), 15 patients (6 decompression and 9 fixation) in Group B had salvage surgery. These 2nd surgeries were performed more than 8 years after initial intervention. Degenerative changes were detected in some cases. Disc narrowing at adjacent level was more seen in Group A. Angular instability was more seen in Group B. This single anterior procedure, Group B, might possess the possibility to reduce degenerative changes compared to anterior and posterior surgery (Group A). Though, even in single anterior access, postoperative aging was still observed.
Discussion
Mini-ALIF procedure has many advantages. One is to pass through the neural arch. It can prevent any intraoperative complications and unfavorable conditions like postoperative neural adhesion. Moreover the anterior procedure with the cage and screw fixation can skip posterior procedure. It is good for preservation of back muscle and can reduce postoperative symptoms. We expect that this single stage procedure might be useful for reducing further degenerative changes.
Conclusions
We reviewed our surgical outcomes of mini-ALIF for degenerative spondylolisthesis. It was MIS procedure and showed acceptable outcomes. The single anterior technique with anterior cage can skip posterior procedure and preserve posterior elements. It might reduce postoperative symptoms and adjacent degenerative changes.