Minimally Invasive Spinal Fusion More Cost Effective in Every Way

By John Henry Dreyfuss, staff.

Save to PDF OrthopedicsEvidence-Based MedicinePerformance-Based Medicine By
  • Minimally invasive spinal (MIS) fusion results in lower direct and indirect costs.
  • MIS postoperative pain can be effective controlled with nonopioid epidural analgesia.
  • MIS results in fewer complications and greater patient satisfaction.
  • MIS is associated with reduced blood loss, decreased length of stay, decreased complication rates.

The authors of a systematic review of randomized and non-randomized comparative studies report that minimally invasive spinal transforaminal lumbar interbody fusion (MIS) (Figure 1) resulted in consistently improved perioperative outcomes versus open transforaminal lumbar interbody fusion (TPLIF). The study, reported recently in Spine, evaluated outcomes including operative time, estimated blood loss, and length of hospital stay. The authors found no significant differences in patient reported outcomes or complication rates between the 2 groups at final follow-up.

Minimally invasive approaches to lumbar fusion have been undertaken by many spine surgeons as an alternative to open surgery. The objective has been to decrease patient morbidity and improve clinical and patient reported outcomes, and to produce secondary cost-savings.


Figure 1. Minimally invasive lumbar fusion surgery.

The Analysis

The authors conducted a systematic review of studies comparing MIS to open TPLIF for degenerative lumbar conditions (Figure 3). The reviewed studies included ≥10 patients in each arm and reported ≥1 clinical, perioperative, radiographic, adverse event, or economic outcome. In all the reviewers examined 45 studies with 3,472 subjects undergoing MIS fusion and 5,925 having an open procedure.

There were no significant differences in operative time between the 2 groups. Patients undergoing MIS fusion consistently demonstrated less blood loss (16.1% to 88.7%) and shorter hospital stays (15.0% to 64.0% shorter). There were no significant differences in variably of visual analogue scale (VAS) pain scores, Oswestry Disability Index (ODI), SF-36, SF-12 or EQ-5D scores between the 2 techniques at intermediate to long-term follow-up (12 to 60 months). Complication rates and fusion rates were also equivalent between the 2 groups. Economic studies demonstrate cost savings in favor of MIS fusion ranging from 2.5% to 49.3%.


The reviewer concluded that “Limited quality comparative observational cohort and randomized controlled studies of MIS versus open TPLIF consistently demonstrate improved perioperative outcomes including operative time, estimated blood loss and length of stay with no significant difference in patient reported outcomes or complication rates between the 2 groups at final follow-up. Increasing economic data suggests both direct and indirect cost savings in favor of MIS fusion.”

Pain Control

The authors of a study published in the European Spine Journal in 2016 reported results of prospective, randomized, comparative study of postoperative pain control using an epidural catheter in patients undergoing posterior lumbar interbody fusion (Figure 2). The study compared the efficacy of continuous epidural infusion analgesia (ED) with 0.2 % ropivacaine versus IV PCA with fentanyl.


Figure 2. Lumbar fusion 7 months postop.
The Analysis

Patients were randomly assigned to 1 of 2 groups: the epidural group (ED; N=51) and the IV PCA group (IV; N=43). “The epidural catheter tip was placed one level cephalad to the level of the PLIF in patients in the ED group. Patients were assessed by determining the pain score, cumulative opioid requirement, adverse effects, and satisfaction.

Pain score comparisons between the ED group and the IV group, respectively, were as follows:

  • Immediate postoperative status: 2.1±1.5 vs. 7.2±2.1, P=0.01
  • Postoperative day 1: 2.3±1.9 vs. 6.8±2.3, P=0.02
  • Postoperative day 2: 1.9±1.8 vs. 5.4±2.1, P=0.02
  • Postoperative day 3: 1.5±1.6 vs. 3.9±1.9, P=0.03
  • Postoperative day 4: 3.8±2.1 vs. 3.1±1.9, P=0.4

Lower levels of opioids were required in the ED group, and fewer opioid-related complications developed in the patients in this group. Complications related to the use of epidural catheters were comparable between the 2 groups. Patient satisfaction with postoperative pain control was higher in the ED group, the authors noted.


In comparison with the use of IV PCA only, continuous epidural infusion of ropivacaine resulted in lower pain scores and lower opioid consumption. Patient satisfaction scores were higher in the ED group.

Postoperative Outcomes and Adverse Events

A meta-analysis and systematic review published in the Journal of Neurosurgery: Spine in 2015 examined perioperative outcomes and adverse events following minimally invasive versus open posterior lumbar fusion.


Figure 3. Degenerative disk disease on MRI.

The Analysis

The authors performed systematic review of the Medline, EMBASE, PubMed, Web of Science, and Cochrane databases. All analyzed studies were either randomized controlled trials (RCTs) or comparative cohort studies that included ≥10 patients undergoing MIS or open TLIF/PLIF for degenerative lumbar spinal disorders. All studies reported ≥1 of the following:

  • Clinical outcome measure;
  • Perioperative clinical or process measure;
  • Radiographic outcome;
  • Or adverse events.

The reviewers obtained 26 studies (856 patients in the MIS cohort, 806 patients in the open cohort) that met the inclusion criteria. No significant differences were found with regard to age, sex, surgical levels, or diagnosis.

The meta-analysis revealed changes in the perioperative outcomes of mean estimated blood loss, time to ambulation, and length of stay favoring an MIS approach by 260 mL (P<0.00001), 3.5 days (P=0.0006), and 2.9 days (P<0.00001), respectively.

Operative time was not significantly different between the surgical techniques (P=0.78). There was no significant difference in surgical adverse events (P=0.97), but patients undergoing MIS were significantly less likely to experience medical adverse events (risk ratio [MIS vs open]=0.39, 95% confidence interval 0.23-0.69, P=0.001). No differences were observed in nonunion (P=0.97) or reoperation rates (P=0.97). Mean ODI scores were slightly better among the patients undergoing MIS (n=346) versus open TLIF/PLIF (n=346) at a median follow-up time of 24 months (mean difference [MIS - open]=3.32, P=0.001).


Patient-reported clinical outcomes were similar between the two techniques. “A meta-analysis of adverse event data suggests equivalent rates of surgical complications with lower rates of medical complications in patients undergoing minimally invasive TLIF/PLIF compared with open surgery,” the authors concluded. “The quality of the current comparative evidence is low to very low, with significant inherent bias,” they noted.

Blood Loss, Length of Stay, and Complication Rates

Results of a meta-analysis published in Neurosurgery in 2015 suggest that minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is associated with reduced blood loss, decreased length of stay, decreased complication rates. However, patients were exposed to increased levels of radiation during the procedure. The rates of fusion and operative time are similar between MI-TLIF and open transforaminal lumbar interbody fusion (O-TLIF).


Figure 4. Sagittal CT scan showing spondylolysis of L5.

The Analysis

The reviewers identified 30 studies that met inclusion criteria. A random-effects meta-analysis was performed by using both pooled and subset analyses based on study type. Patients undergoing MI-TLIF experienced reduced blood loss (P<0.001), decreased length of hospital stay (P<0.001), and reduced rates of complications (P=0.001). However, MI-TLIF patients were exposed to higher doses of radiation exposure (P<0.001).

No differences were found in fusion rate (P=0.61) or operative time (P=0.34). A decrease in late VAS-back pain scores was demonstrated for MI TLIF (P<0.001). No differences were found in early VAS-back pain scores, early ODI, or late ODI.


MI-TLIF was associated with reduced blood loss, decreased length of stay, decreased complication rates, and increased radiation exposure, the authors concluded. The rates of fusion and operative time were similar between MI-TLIF and O-TLIF. “Differences in long-term outcomes in MI-TLIF vs O-TLIF are inconclusive and require more research, particularly in the form of large, multi-institutional prospective randomized controlled trials,” they noted.

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