Clinical Comparison of Two MIS Fusion Techniques for Lumbar Spondylolysis and Isthmic Spondylolisthesis

Presented at SMISS Annual Forum 2016
By Ryo Fujita MD
With Yoshihisa Kotani MD, PhD

Disclosures: Ryo Fujita MD None, Yoshihisa Kotani MD, PhD None

Introduction

Recently, minimally invasive lumbar spinal fusion is often selected for lumbar spondylolysis and spondylolisthesis. There is an increased possibility that it can reduce the damage of lumbosacral posterior muscles, which may lead to reduction of the residual low back pain after surgery. 

Aims/Objectives

Aim of our study is to compare two MIS fusion techniques for lumbar spondylolysis and isthmic spondylolisthesis. 

Methods

A total of 35 patients (13-80 yo, 2 lumbar spondylolysis, 33 lumbar isthmic spondylolisthesis) received single-level spine fusion with one of the following techniques: MIS-PLF or MIS-TLIF with Mini-Wiltse approach using pedicle screws (PS) (mWiltse) versus TLIF with small median incision using modified cortical bone trajectory (mCBT) screw (midline lumbar fusion: MIDLF). There were 17 cases of MIS-PLF or TLIF and 18 cases of MIDLF. The clinical evaluation parameters were operation time, intraoperative bleeding, rates of bone union, screw loosening, complications, pain by VAS, overall functional outcome by the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) score, and inflammatory markers of serum creatine kinase (CK) and C-reactive protein (CRP). 

Results

The average follow-up period was 12.1months (8 - 24). Mean operation time was significantly shorter in MIDLF (119min) vs mWiltse (161min, p=0.01). The intraoperative blood loss was significantly less in MIDLF (96ml) vs mWiltse (330ml, p=0.01). The bone union rates were 100% in MIDLF and 94% in mWiltse. Regarding JOABPEQ score, MIDLF showed a better effective rate compared to that in mWiltse in terms of pain, lumbar function, and mental disability. The MIDLF showed a significantly lower CK (327) and CRP (1.3) to mWiltse (1001 and 2.1) on POD1.

Conclusions

The lumbosacral posterior fusion by open technique tends to be highly invasive to the posterior muscles due to large PS trajectory. Since the main lesion of the lumbar spondylolysis and isthmic spondylolisthesis is often located at the neural foramen, the use of mini-Wiltse approach is beneficial to the operation being less invasive. In turn, the MIDLF requires less tissue dissection in the lateral part of facet with the preservation of medial branch of posterior ramus. In conclusion, the advantage of MIDLF over mini-Wiltse PLF and TLIF was demonstrated in terms of invasiveness, low back pain, and lumbar spine function.