MASTERS-D Study: A Prospective, Multicenter, Pragmatic, Observational, Data-Monitored Trial of Minimally Invasive Fusion to Treat Degenerative Lumbar Disorders, One-Year Follow-Up

Abstract

The objective of the study is to assess effectiveness and safety of minimally invasive lumbar interbody fusion (MILIF) for degenerative lumbar disorders (DLD) in daily surgical practice and follow up with patients for one year after surgery. A prospective, multicenter, pragmatic, monitored, international outcome study in patients with DLD causing back/leg pain was conducted (19 centers). Two hundred fifty-two patients received standard of care available in the centers. Patients were included if they were aged >18 years, required one- or two-level lumbar fusion for DLD, and met the criteria for approved device indications. Primary endpoints: time to first ambulation (TFA) and time to surgery recovery (TSR). Secondary endpoints: patient-reported outcomes (PROs)--back and leg pain (visual analog scale), disability (Oswestry Disability Index (ODI)), health status (EQ-5D), fusion rates, reoperation rates, change in pain medication, rehabilitation, return to work, patient satisfaction, and adverse events (AEs). Experienced surgeons (≥30 surgeries pre-study) treated patients with DLD by one- or two-level MILIF and patients were evaluated for one year (NCT01143324). At one year, 92% (233/252) of patients remained in the study.

Primary outcomes: TFA, 1.3 ±0.5 days and TSR, 3.2 ±2.0 days.

Secondary outcomes: Most patients (83.3%) received one level MILIF; one (two-level) MILIF mean surgery duration, 128 (182) min; fluoroscopy time, 115 (154) sec; blood loss, 164 (233) mL; at one year statistically significant (P<.0001) and clinically meaningful changes from baseline were reported in all PROs--reduced back pain (2.9 ±2.5 vs. 6.2 ±2.3 at intake), reduced leg pain (2.2 ±2.6 vs. 5.9 ±2.8), and ODI (22.4% ± 18.6 vs. 45.3% ± 15.3), as well as health-related quality of life (EQ-5D index: 0.71 ±0.28 vs. 0.34 ±0.32). More of the professional workers were working at one year than those prior to surgery (70.3% vs. 55.2%). Three AEs and one serious AE were considered procedure-related; there were no deep site infections or deaths. This is the first study evaluating MILIF for treatment of DLD in daily clinical practice. Clinically significant improvements were observed in all endpoints. Short-term post-surgery improvements (four weeks) were maintained through one year with minimal complications. Our results suggest that MILIF has good-to-excellent outcomes for the treatment of DLD in a broad patient population under different clinical conditions and healthcare delivery systems.

Keywords: degenerative lumbar disorders; minimal access spinal technologies; minimally invasive lumbar fusion; patient-reported outcomes; pragmatic.

Figure 1. Improvement of back and leg pain.

Back (a) and leg (b) pain intensity scores reported preoperatively and postoperatively on a 10 cm visual analog scale (VAS) where 0 = minimal pain intensity or pain frequency and 10 = maximal pain intensity or pain frequency (total population, n=252). ***P < .0001 for difference between preoperative (back 6.2 ±2.3, leg 5.9 ±2.8) and postoperative scores at two days (back 4.5 ±2.3, leg 2.6 ±2.7), surgery recovery day (back 3.9 ±2.2, leg 2.2 ±2.5), discharge (back 3.1 ±2.1, leg 1.9 ±2.3), four weeks (back 2.9 ±2.2, leg 2.5 ±2.6), three months (back 2.9 ±2.2, leg 2.1 ±2.4), six months (back 2.9 ±2.4, leg 2.0 ±2.4), and twelve months (back 2.9 ±2.5, leg 2.2 ±2.6).

Figure 2. Improvement of patient disability.

Oswestry disability index (ODI) scores (calculated in %) reported preoperatively and at four weeks and three, six, and twelve months postoperatively on a 0% to 100% scale, where 0% = minimal disability and 100% = maximal disability (total population, n=252).***P < .0001.

Figure 3. Overall amelioration in quality of life.

Percentages of patients who reported on five EQ-5D domains preoperatively vs. four weeks, three months, six months and twelve months.

Figure 4. Decreased frequency and potency of pain medication for lumbar spine in the past week.

Percentages may not equal 100% because combinations of medications may have been used by the same patient.