Comparison of long-term effect between minimally invasive and open approaches in one-level posterior lumbar interbody fusion: a 10-12 year prospective study

Objective To compare the long-term effect between minimally invasive (MIS) and open approaches in one-level posterior lumbar interbody fusion (O-PLIF) after more than 10 years follow up. Methods All 131 patients (lumbar spine lesions) in our hospital were randomized into MIS-PLIF group and O-PLIF group from March 2006 to March 2008. In MIS-PLIF group, there are 66 patients, 34 males and 32 females, with the average of 52.3±6.7 years old (range from 40 to 63). In O-PLIF group, there are 65 patients, 29 males and 36 females, with the average of 51.1±6.9 years old (range from 46 to 63). Regarding March 2018 as last follow-up, differences in intervertebral disc height and segmental lordosis restoration of the operation segment, lumbar lordosis restoration, multifidus cross section area (CSA), multifidus atrophy rate, fusion rate, visual analogue scale(VAS) for back and leg pain, Oswestry Disability Index(ODI), Japanese Orthopaedic Association cores (JOA) and postoperative long-term complications were evaluated between the two groups. The related risk factors of postoperative long-term complications were evaluated in further analysis. Results Complete follow-up data were available on 37 patients in MIS-PLIF group and 35 patients in O-PLIF group, with the follow-up rate of 56.1% and 53.8% respectively, and with the mean follow-up time of 134.5 ±8.4 and 137.1±5.8 months respectively. At three time nodes of one year after operation, five years after operation and last follow-up after operation, there were significant differences in lumbar lordosis restoration (one year after operation and last follow-up after operation)(5.0°±2.3° vs. 3.9°±1.4°; 4.7°±2.4° vs. 3.7°±1.5°), multifidus CSA (965.4±164.9 mm2vs. 884.9±168.2 mm2; 891.1±155.9 mm2vs. 783.2±163.0 mm2; 764.8±148.3 mm2 vs. 643.5±150.0 mm2), multifidus atrophy rate (8.5%±2.5% vs. 16.6%±5.8%; 15.6%±3.5% vs. 26.2%±7.4%; 27.6%±6.5% vs. 39.3%±9.3%), postoperative VAS for back pain (2.2±1.0 vs. 2.9±1.2; 1.7±0.9 vs. 2.2±1.0; 1.4±1.0 vs. 2.2±1.2), JOA score (22.3±3.8 vs. 19.9±4.2; 23.1±4.3 vs. 19.3±3.9; 22.4±4.2 vs. 19.6±4.0) and ODI (11.6%±4.8% vs. 22.0%±7.7%; 9.4%±3.9% vs. 12.3%±4.9%; 8.6%±4.0% vs. 11.0%±4.6%) between the two groups (P 0.05). Intractable back pain and adjacent segment disease were the major postoperative long-term complications for MIS-PLIF group (3 cases and 2 cases) and O-PLIF group (10 cases and 7 cases), and the difference was statistically significant in the intractable back pain incidence rate (8.5% vs. 28.6%, χ2=5.090, P=0.024), but not in the adjacent segment disease(5.4% vs. 20%, χ2=0.002, P=0.061). What's more, patients with intractable back pain suffered more obviously multifidus atrophy than patients without intractable back pain at three time nodes of one year after operation (19.4±4.4% vs. 10.9±5.1%, P<0.05), five years after operation (30.2±5.4% vs. 18.7±6.7%, P<0.05) and last follow-up after operation (44.5±5.7% vs. 30.8±8.9%, P<0.05). Conclusion In the long-term follow up, compared with O-PLIF, MIS-PLIF had advantages in better maintenance of lumbar lordosis, protection of the multifidus muscle, reduced lower back pain, JOA score, ODI score and intractable back pain incidence rate. Multifidus atrophy may be a related risk factor of intractable back pain. Key words: Lumbar vertebrae; Surgical procedures, minimally invasive; Spinal fusion