Short-term and long-term outcomes of minimally invasive and open transforaminal lumbar interbody fusions: is there a difference?

OBJECT: Previous studies comparing minimally invasive transforaminal lumbar interbody fusion (MITLIF) with open TLIF have demonstrated that MITLIF reduces blood loss and decreases postoperative pain while preserving fusion rates and reducing complications. In this study, the authors wanted to compare outcomes of MITLIF with those of open TLIF to determine whether MITLIF also improves postoperative functional mobility and decreases the usage of pain medication.
METHODS: In total, 75 consecutive patients who underwent either single-level open TLIF or MITLIF at the University of California, San Francisco, between 2006 and 2011 were included, and patients were followed up for an average of 5.05 years. Fifty patients underwent MITLIF and 25 underwent open TLIF. Primary outcomes included administration of morphine-equivalent narcotics and functional status on postoperative Day 1. Secondary outcomes included operative characteristics, complications, long-term fusion rates, and visual analog scale (VAS) scores.
RESULTS: No statistically significant differences in age, sex, body mass index (BMI), level of disease, or surgical indication were detected between the open TLIF and MITLIF groups. Similarly, preoperative medication usage did not significantly differ between these groups. Intraoperatively, compared with TLIF, MITLIF resulted in decreased lengths of operation, lower blood loss, and fewer complications (p < 0.05). Total administration of morphine-equivalent pain medication in the hospital also tended to be lower in the MITLIF than in the TLIF group. Functional assessment by physical therapy on postoperative Day 1 demonstrated higher function in the MITLIF patients for transfer-related tasks, ambulatory ability, and distance walked than in the TLIF patients (p < 0.05). This translated to shorter inpatient hospitalizations (6.05 vs 4.8 days for open TLIF vs MITLIF patients, respectively, p = 0.006) and an average cost reduction of $3885 per MITLIF patient. Long-term fusion rates were 92% in the MITLIF group and 100% in the open TLIF group (p = 0.09). Preoperative VAS pain scores were 7.1 for the MITLIF patients and 7.6 for the TLIF patients (p = 0.26). At the last follow-up, the reported VAS pain score was 2.9 in the MITLIF patients and 3.5 in the open TLIF patients, but this difference was not statistically significant (p = 0.25). There was also no statistically significant difference in the degree change in this score (p = 0.44).
CONCLUSIONS: The MITLIF approach achieves improved functional mobility, decreases the usage of postoperative pain medication, and significantly reduces cost compared with open TLIF while preserving long-term fusion rates. To the authors' knowledge, this is the first study comparing the postoperative usage of pain medication between treatments in the postoperative period before discharge.