Mid-term clinical results of minimally invasive decompression and posterolateral fusion with percutaneous pedicle screws versus conventional approach for degenerative spondylolisthesis with spinal stenosis

Abstract

Introduction: In order to minimize perioperative invasiveness and improve the patients' functional capacity of daily living, we have performed minimally invasive lumbar decompression and posterolateral fusion (MIS-PLF) with percutaneous pedicle screw fixation for degenerative spondylolisthesis with spinal stenosis. Although several minimally invasive fusion procedures have been reported, no study has yet demonstrated the efficacy of MIS-PLF in degenerative spondylolisthesis of the lumbar spine. This study prospectively compared the mid-term clinical outcome of MIS-PLF with those of conventional PLF (open-PLF) focusing on perioperative invasiveness and patients' functional capacity of daily living.

Materials and methods: A total of 80 patients received single-level PLF for lumbar degenerative spondylolisthesis with spinal stenosis. There were 43 cases of MIS-PLF and 37 cases of open-PLF. The surgical technique of MIS-PLF included making a main incision (4 cm), and neural decompression followed by percutaneous pedicle screwing and rod insertion. The posterolateral gutter including the medial transverse process was decorticated and iliac bone graft was performed. The parameters analyzed up to a 2-year period included the operation time, intra and postoperative blood loss, Oswestry-Disability Index (ODI), Roland-Morris Questionnaire (RMQ), the Japanese Orthopaedic Association score, and the visual analogue scale of low back pain. The fusion rate and complications were also reviewed.

Results: The average operation time was statistically equivalent between the two groups. The intraoperative blood loss was significantly less in the MIS-PLF group (181 ml) when compared to the open-PLF group (453 ml). The postoperative bleeding on day 1 was also less in the MIS-PLF group (210 ml) when compared to the open-PLF group (406 ml). The ODI and RMQ scores rapidly decreased during the initial postoperative 2 weeks in the MIS-PLF group, and consistently maintained lower values than those in the open-PLF group at 3, 6, 12, and 24 months postoperatively. The fusion rate was statistically equivalent between the two groups (98 vs. 100%), and no major complications occurred.

Conclusion: The MIS-PLF utilizing a percutaneous pedicle screw system is less invasive compared to conventional open-PLF. The reduction in postoperative pain led to an increase in activity of daily living (ADL), demonstrating rapid improvement of several functional parameters. This superiority in the MIS-PLF group was maintained until 2 years postoperatively, suggesting that less invasive PLF offers better mid-term results in terms of reducing low back pain and improving patients' functional capacity of daily living. The MIS-PLF utilizing percutaneous pedicle screw fixation serves as an alternative technique, eliminating the need for conventional open approach.

Fig. 1

Percutaneous rod placement and instrumentation with the Sextant system (Medtronic, Memphis, TN, USA)

Fig. 2

a The use of an expandable retractor provides an enlarged surgical area and sufficient illumination for MIS-PLF. b After the meticulous decortication of bilateral posterolateral gutters, the morcellated cancellous iliac bone was grafted bilaterally in the MIS-PLF group

Fig. 3

Intraoperative and postoperative blood loss (days 1 and 2) in the MIS-PLF and open-PLF groups. Asterisks indicate the statistically significant difference between the MIS-PLF and open-PLF groups at the P = 0.01 level

Fig. 4

Time-related change of ODI from the preoperative phase until 24 months postoperatively in the MIS-PLF and open-PLF groups. Asterisks depict the statistically significant differences between the MIS-PLF and open-PLF groups at each time period (P < 0.01)

Fig. 5

Time-related change of RMQ scores from the preoperative stage until 24 months postoperatively in the MIS-PLF and open-PLF groups. Asterisks depict statistically significant differences between the MIS-PLF and open-PLF groups at each time period (P < 0.01)

Fig. 6

Average low back pain VAS at preoperative, and postoperative days 1, 3, 7, and 14 in the MIS-PLF and open-PLF groups. Asterisks depict statistically significant differences between the MIS-PLF and open-PLF groups at the P = 0.02 level

Fig. 7

Follow-up radiograph and parasagittal CT image of MIS-PLF at 29 months postoperatively. a A-P radiograph demonstrating a solid and continuous posterolateral fusion. b A parasagittal CT image of the solid continuity of fusion