Outcomes of direct lateral interbody fusion (DLIF) in an Australian cohort

Abstract

Background: Direct lateral interbody fusion (DLIF) mitigates many of the vascular complications and bony resections associated with other interbody fusion techniques. However, there are concerns regarding postoperative neural complications and that indirect decompression of the foramen has not been consistently demonstrated. This study prospectively assessed the clinical and radiological outcomes and the complication rates of the DLIF approach.

Methods: A prospective review was conducted of the first 50 consecutive DLIF cases of a single neurosurgeon between 2010 and 2014. Clinical outcomes were assessed using Visual Analogue Scale (VAS), Oswestry Disability Index (ODI) and Roland Morris Disability Questionnaire (RMDQ) surveys. Radiological outcomes, including spondylolisthesis, disc height, local disc angle, lumbar lordosis and foraminal height and width, were measured using Surgimap Spine software at the preoperative, 6 weeks, 6 months, and 12 months postoperative follow-up. Complication rates were also reported.

Results: A total of 50 patients (84 levels) were treated with DLIF. The mean patient age was 68.2±9.8 years and 62.0% were female. At latest follow-up, mean VAS pain score improved from 7.7±1.5 to 1.9±0.9 (P<0.0001), mean ODI improved from 42.1±14.5 to 16.9±6.7 (P<0.0001) and mean RMDQ score improved from 12.1±5.2 to 6.2±4.7 (P<0.0001). Mean spondylolisthesis reduced from 7.5%±6.5% to 1.3%±1.1% at 6 weeks (P<0.0001), 0.95%±0.74% at 6 months (P<0.0001) and recurred to 1.9%±1.7% at 12 months postoperatively (P=0.0006). Mean anterior disc height improved from 7.3±3.2 to 11.6±2.5 mm at 6 weeks (P<0.0001), 12.2±3.3 mm at 6 months (P<0.0001) and 9.8±2.1 mm at 12 months (P=0.0032) postoperatively. Mean posterior disc height improved from 4.4±2.0 to 6.8±2.1 mm at 6 weeks (P<0.0001), 6.6±2.5 mm at 6 months (P=0.0003), and 5.9±1.4 mm at 12 months (P=0.0039) postoperatively. Mean local disc angle improved from 7.0°±3.7° to 9.2°±3.3° at 6 weeks (P=0.0072), 10.4°±3.9° at 6 months (P=0.0013) and 8.2°±2.9° at 12 months (P=0.2487) postoperatively. No significant postoperative changes in lumbar lordosis were observed. Mean foraminal height improved from 18.3±3.5 to 21.5±3.9 mm at 6 weeks (P=0.0004), 20.6±3.4 mm at 6 months (P=0.0266), and 18.7±1.9 mm at 12 months (P=0.8021) postoperatively. Mean foraminal width improved from 7.9±2.0 to 10.2±2.8 mm at 6 weeks (P=0.0001), 9.4±2.6 mm at 6 months (P=0.0219) and 8.3±1.6 mm at 12 months (P=0.5734) postoperatively. Fusion rate at 6 and 12 months was 62.2% and 89.2%, respectively. A total of 6 patients (12%) had postoperative complications. Three patients (6%) had pain-related psoas muscle weakness and 3 patients (6%) had sensory neural complications that had resolved entirely by 8 and 16 weeks postoperatively, respectively.

Conclusions: The study provides encouraging short and medium-term clinical and radiological results for DLIF. In this patient series, there was a low complication rate with no permanent neural injury reported.

Keywords: Direct lateral interbody fusion (DLIF); clinical outcomes; lateral lumbar interbody fusion (LLIF); minimally invasive spine surgery; radiological outcomes.

Figure 1

Depiction of how measurements were conducted. (A) Anterior disc height and posterior disc height; (B) foraminal height and foraminal width; (C) local disc angle; (D) spondylolisthesis; (E) lumbar lordosis.

Figure 2

Pre- and postoperative (A) Visual Analogue Scale score; (B) Oswestry Disability Index (%); (C) Roland Morris Disability Questionnaire. *, statistically significant.

Figure 3

Pre- and postoperative measurements of (A) spondylolisthesis (%); (B) anterior disc height (mm); (C) posterior disc height (mm); (D) local disc angle (deg); (E) foraminal height (mm); (F) foraminal width (mm). *, statistically significant.