Lower Incidence of ASP Requiring Surgery With Minimally Invasive TLIF Than With Open PLIF: A Long-term Analysis of Adjacent Segment Survival.

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To assess the incidence of and risk factors for adjacent segment pathology (ASP) requiring surgery among patients previously treated with spinal fusion. Survival of the adjacent segment was compared in patients undergoing open posterior lumbar interbody fusion (O-PLIF) versus minimally invasive transforaminal interbody fusion (MI-TLIF).

SUMMARY OF BACKGROUND DATA

Compared with O-PLIF, MI-TLIF may reduce ASP in the long term by preserving more of the paraspinal muscle and ligamentous structures connected to adjacent segments.

METHODS

The study population consisted of 740 consecutive patients who had undergone lumbar spinal fusion of 3 or fewer segments. O-PLIF was performed in 564 patients, and MI-TLIF in 176 patients. The incidence and prevalence of revision surgery for ASP were calculated using the Kaplan-Meier method. A risk factor analysis was performed using the log-rank test and a Cox regression analysis.

RESULTS

After index spinal fusion, 26 patients (3.5%) underwent additional surgery for ASP. Kaplan-Meier analysis predicted a disease-free survival rate of adjacent segments in 87.2% at 10 years after the index operation. The incidence of ASP requiring surgery within 10 years was 16.4% after O-PLIF and 6.1% after MI-TLIF ( P =0.045). This result was supported by the Cox regression analysis, which showed a significant difference between MI-TLIF and O-PLIF ( P =0.034). The hazard ratio of revision surgery was about 3 times higher with O-PLIF than with MI-TLIF. Patients 65 years or older at the time of the index operation were 2.9 times more likely to undergo revision surgery than those younger than 65 years ( P =0.015).

CONCLUSIONS

MI-TLIF results in less ASP requiring surgery than O-PLIF. 65 years or older is an independent risk factor for ASP. By preserving the soft tissues, MI-TLIF may result in a lower incidence of ASP than the open technique.

LEVEL OF EVIDENCE

Level III.