Correlation of Vertebral Bone Quality and Paraspinal Muscle Changes With Adjacent Segment Degeneration After Transforaminal Lumbar Interbody Fusion Operation

Objective To investigate the correlation of vertebral bone quality (VBQ) and paraspinal muscle changes with adjacent segment degeneration (ASD) after transforaminal lumbar interbody fusion (TLIF) through a retrospective analysis of patients who have undergone TLIF for lumbar degenerative diseases (LDD).

Methods A total of 98 patients who underwent TLIF surgical treatment for LDD between January 2016 and December 2022 at Shenzhen People's Hospital were selected. Well-established follow-up imaging data were available for all subjects who were divided into two groups, the ASD group (n=43) and the non-ASD (N-ASD) group (n=55), according to whether they met the ASD evaluation criteria. Data on the basic characteristics of the patients in both groups were collected, and the relevant parameters, including VBQ and the total cross-sectional area (TCSA) and the functional cross-sectional area (FCSA) of psoas major (PM), erector spinae (ES), and multifidus (MF), were measured by magnetic resonance imaging of the lumbar spine performed preoperatively and at the last follow-up. Then, the relative fat infiltration (RFI) was calculated from the above metrics accordingly. Logistic regression analysis was conducted to investigate the risk factors for ASD.

Results The incidence of ASD was 43.9% (n=43) at the final follow-up. The mean follow-up time was (27.23±4.15) months. The age, body mass index (BMI), preoperative bone mineral density (BMD), preoperative VBQ, ΔRFI_PM, and ΔRFI_ES+MF showed significant differences between the ASD and N-ASD groups (P<0.05). According to the results of the logistic regression analysis, BMI (odds ratio OR=1.450, 95% confidence interval CI: 1.081-1.945, P=0.013), preoperative VBQ (OR=6.191, 95% CI: 1.692-22.657, P=0.006), and ΔRFI_ES+MF (OR=1.117, 95% CI: 1.007-1.238, P=0.037) were independent risk factors for ASD.

Conclusion The incidence of postoperative ASD in patients who have undergone TLIF for LDD was found to be associated with higher BMI, preoperative VBQ, and increased postoperative relative fat infiltration of the ES and MF muscles. Consequently, it is advisable to prioritize the intraoperative protection of the paraspinal muscles during TLIF. In the postoperative period, it is essential to strengthen exercises of the lower back muscles and to optimize bone mass and weight management, which is conducive to reducing the risk of ASD in the postoperative period.