Can paraspinal muscle degeneration be a reason for refractures after percutaneous kyphoplasty? A magnetic resonance imaging observation

BACKGROUND: Vertebral augmentation (VA) techniques are used to treat acute osteoporotic vertebral compression fractures (OVCFs). However, the incidence of recurrent vertebral fractures after VA is controversial. Various factors have been discussed in the literature, but no convincing study on the quality of paraspinal muscles has been reported. The purposes of this study were to evaluate the changes in paraspinal muscles and discuss the relationship between paraspinal muscle degeneration and vertebral refractures after percutaneous kyphoplasty (PKP). METHODS: This retrospective study was conducted in patients who underwent PKP for an initial OVCF between July 2017 and August 2018. Patients were followed up and categorized in the refractured or non-refractured group. A final magnetic resonance imaging (MRI) scan and a preoperative MRI scan were used to determine the measurements. The paraspinal muscles at the mid-height level of the initial fractured vertebral body were measured using regions of interest (ROIs), including the cross-sectional area (CSA) and signal intensity (SI). The changes in the observed data were compared between the groups using rank-sum tests. RESULTS: Overall, 92 patients were enrolled in the study; 33 of them sustained vertebral refractures during the follow-up and the other 59 patients did not. There were no significant differences in terms of sex, age, preoperative bone mineral density, and body mass index between the groups (all, P > 0.05). The refractured group had a significantly higher decrease in the ROI-CSA and CSA/SI, and a higher increase in ROI-SI, compared with the preoperative data (all, P < 0.05). CONCLUSIONS: The quality of paraspinal muscles significantly decreased in patients with new OVCFs after PKP. This brings a new perspective to the study of postoperative recurrent fractures; patients and physicians need to pay more attention to the efficacy of bed rest and bracing.