The effect of posterior lumbar dynamic fixation and intervertebral fusion on paraspinal muscles

BACKGROUND

The aim of this study was to analyze the effect of unilateral K-rod dynamic internal fixation on paraspinal muscles for lumbar degenerative diseases.

METHODS

This study retrospectively collected 52 patients who underwent lumbar surgery with the K-rod group or PLIF. The operation time, intraoperative blood loss, postoperative drainage volume, postoperative exercise time were compared in the two groups. The visual analog scale (VAS) score and the oswestry dysfunction index (ODI) were employed to evaluate the clinical outcomes. The functional cross-sectional area (FCSA) of the paraspinal muscles and paraspinal muscles fat infiltration were measured to assess on the paraspinal muscles.

RESULTS

As compared with the PLIF group, the operation time, the postoperative time in the field, and the average postoperative hospital stay in the K-rod internal fixation group were significantly shortened. At the last follow-up, both the groups showed significant improvement in the VAS score and ODI. The FCSA atrophy of the upper and lower adjacent segments (UAS and LAS) of the K-rod internal group was significantly less than that of the PLIF group. The extent of increase in the fatty infiltration of the paraspinal muscles in the K-rod group was significantly lesser than that in the PLIF group. The postoperative low back pain of the two groups of patients was significantly positively correlated with the FCSA atrophy.

CONCLUSIONS

As compared to PLIF, the posterior lumbar unilateral K-rod dynamic internal fixation showed significantly lesser paraspinal muscle atrophy and fatty infiltration, which were significantly positively correlated with postoperative low back pain.

Quantitative analysis of paraspinal muscle atrophy after oblique lateral interbody fusion alone vs. combined with percutaneous pedicle screw fixation in patients with spondylolisthesis

BACKGROUND

There is no available literature for comparison on muscle atrophy between the "stand-alone" oblique lateral interbody fusion (OLIF) and regular OLIF (i.e., combined with percutaneous pedicle screws fixation (PPSF) in patients with spondylolisthesis). This study aimed to identify changes in back muscle atrophy between the two surgeries.

METHODS

This was a retrospective cohort study of patients who underwent OLIF or OLIF+PPSF at Beijing Jishuitan Hospital and Shanghai ChangZheng Hospital between 07/2014 and 10/2017. Computed tomography (CT) was used to measure functional cross-sectional area (FCSA) and fat infiltration percentage (FIP) of the multifidus and erector spinae before and 24 months after surgery.

RESULT

There were no differences in FCSA and FIP between OLIF (n = 32) and OLIF+PPSF (n = 41) groups before surgery. In the OLIF group, the multifidus and erector spinae FCSA and FIP did not change at 24 months (FCSA: multifidus: from 8.59 ± 1.76 to 9.39 ± 1.74 cm², P = 0.072; erector spinae: from 13.32 ± 1.59 to 13.55 ± 1.31 cm², P = 0.533) (FIP: multifidus: from 15.91 ± 5.30% to 14.38 ± 3.21%, P = 0.721; erector spinae: from 11.63 ± 3.05% to 11.22 ± 3.12%, P = 0.578). In the OLIF+PPSF group, the multifidus and erector spinae FCSA decreased (multifidus: from 7.72 ± 2.69 to 5.67 ± 1.71 cm², P < 0.001; erector spinae: from 12.60 ± 2.04 to 10.15 ± 1.82 cm², P < 0.001), while the FIP increased (multifidus: from 16.13 ± 7.01% to 49.38 ± 20.54%, P < 0.001; erector spinae: from 11.93 ± 3.22% to 22.60 ± 4.99%, P < 0.001). The differences of FCSA and FIP between the two groups at 24 months were significant (all P < 0.001). The patients in the standalone OLIF group had better VAS back pain, and JOA scores than the patients in the OLIF combined group (all P < 0.05) at 1 week and 3 months after surgery. There were two cases (4.9%) of adjacent segment degeneration in the OLIF combined group, while there was no case in the OLIF alone group.

CONCLUSIONS

Standalone OLIF had better clinical outcomes at 1 week and 3 months than OLIF+PPSF in patients with spondylolisthesis. OLIF may not result in paraspinal muscle atrophy at 24 months after surgery.