Paraspinal muscle atrophy after posterior lumbar surgery with and without pedicle screw fixation with the classic technique.

Objectives: Lumbar spine surgery causes a muscular injury during its approach that could worsen long-term postoperative functional results. This study aims to analyze the postoperative paraspinal atrophy associated with two types of intervention.

Material And Methods: Clinical records and lumbar magnetic resonance imaging were collected from a group of 41 patients, 20 underwent laminectomy with lumbar fixation due to lumbar spinal stenosis (fixation group) and another group of 21 underwent hemilaminectomy without fixation due to lumbar disc disease (non-fixation group). In which muscle atrophy was analyzed quantitatively.

Results: We found a negative correlation between age and preoperative muscle, which was higher in those who underwent lumbar fixation (rho = -0.64 p = .002). We also found a positive correlation between preoperative muscle and postoperative atrophy (rho = 0.32 p = .041). In the age, sex and fixation adjusted multivariate linear regression model (R = 0.31), laminectomy with fixation is attributed to 5.3% atrophy (IC95 1.4-9.5%, p = .017); preoperative musculature > 70% is attributed to atrophy of 13.8% (95% CI 5.5%-22%, p = .002). Age did not correlate with postoperative atrophy.

Conclusions: Paraspinal muscle atrophy after lumbar spinal surgery is greater if an extensive approach is performed such as complete laminectomy with bilateral facetectomy and transpedicular fixation. A greater previous musculature regardless of age, sex and type of surgery also predicts greater postoperative atrophy.