Comparison of Clinical and Radiological Results of Posterolateral Fusion and Posterior Lumbar Interbody Fusion in the Treatment of L4 Degenerative Lumbar Spondylolisthesis

Abstract

Study design: Multicenter analysis of two groups of patients surgically treated for degenerative L4 unstable spondylolisthesis.

Purpose: To compare the clinical and radiographic outcomes of posterolateral fusion (PLF) and posterior lumbar interbody fusion (PLIF) for degenerative L4 unstable spondylolisthesis.

Overview of literature: Surgery for lumbar degenerative spondylolisthesis is widely performed. However, few reports have compared the outcome of PLF to that of PLIF for degenerative L4 unstable spondylolisthesis.

Methods: Patients with L4 unstable spondylolisthesis with Meyerding grade II or more, slip of >10° or >4 mm upon maximum flexion and extension bending, and posterior opening of >5 degree upon flexion bending were studied. Patients were treated from January 2008 to January 2010. Patients who underwent PLF (n=12) and PLIF (n=19) were followed-up for >2 years. Radiographic findings and clinical outcomes evaluated by the Japanese Orthopaedic Association (JOA) score were compared between the two groups. Radiographic evaluation included slip angle, translation, slip angle and translation during maximum flexion and extension bending, intervertebral disc height, lumbar lordotic angle, and fusion rate.

Results: JOA scores of the PLF group before surgery and at final follow-up were 12.3±4.8 and 24.1±3.7, respectively; those of the PLIF group were 14.7±4.8 and 24.2±7.8, respectively, with no significant difference between the two groups. Correction of slip estimated from postoperative slip angle, translation, and maintenance of intervertebral disc height in the PLIF group was significantly (p<0.05) better than those in the PLF group. However, there was no significant difference in lumbar lordotic angle, slip angle and translation angle upon maximum flexion, or extension bending. Fusion rates of the PLIF and PLF groups had no significant difference.

Conclusions: The L4-L5 level posterior instrumented fusion for unstable spondylolisthesis using both PLF and PLIF could ameliorate clinical symptoms when local stability is achieved.

Keywords: Degenerative spondylolisthesis; Instability; Posterior lumbar interbody fusion; Posterolateral fusion.

Conflict of interest statement

Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1. Radiologic measurements of (A) percentage slip, (B) disc height, (C) slip angle, and (D) lumbar lordosis. The SA, degree of slip (% of slip), and disc height (h/H) were measured for the sagittal profile. LL was measured for alignment. S, slippage; h, disc height; H, posterior wall height of the proximal vertebral body; SA, slip angle; LL, lumbar lordosis.

Fig. 2. (A–D) Clinical data. There was no significant difference in total JOA score, JOA subscore of back pain, or walking ability between PLF and PLIF groups at each follow-up time point. JOA, Japanese Orthopaedic Association; Preop., preoperative; PLIF, posterior lumbar interbody fusion; PLF, posterior lumbar fusion.

Fig. 3. (A–D) Radiologic data of the operated segment. Postoperative correction was better and the vertebral disc height was higher in the PLIF group, although the preoperative slip angle and translation were not significantly different between the two groups. Preop., preoperative; PLIF, posterior lumbar interbody fusion; PLF, posterior lumbar fusion; h, disc height; H, posterior wall height of the proximal vertebral body. *p<0.05, **p<0.01.

Fig. 4. Radiologic data for the sagittal alignment. Lumbar lordosis was not significantly different between the two groups. Preop., preoperative; PLIF, posterior lumbar interbody fusion; PLF, posterior lumbar fusion.

Fig. 5. (A, B) Radiologic data on maximum flexion and extension. Preoperative instability on maximum flexion and extension was stronger in the PLIF group. However, the PLF group showed instability at 3 and 6 months postoperatively compared to the PLIF group. The instability in the maximum flexion and extension disappeared in both groups. Preop., preoperative; PLIF, posterior lumbar interbody fusion; PLF, posterior lumbar fusion. *p<0.05, **p<0.01.

Fig. 6. Fusion rate. The bony union rate at the final follow-up was not significantly different between the two groups. Preop., preoperative; PLIF, posterior lumbar interbody fusion; PLF, posterior lumbar fusion.