A Convenient Musculoskeletal Assessment Tool for Predicting Mechanical Complications After Posterior Lumbar Interbody Fusion

STUDY DESIGN: Prospective Cohort Study. OBJECTIVE: To establish a simple and clinically available paraspinal muscle and bone density (PMBD) score to predict mechanical complications after lumbar fusion. SUMMARY OF BACKGROUND DATA: Mechanical complications are common issues in posterior lumbar interbody fusion (PLIF). Current evaluations are often unidimensional and complex, with lack of clinical relevance for treatment. METHODS: The study analyzed a cohort of 255 patients (165 women and 90 men) followed for at least 1 year after posterior lumbar interbody fusion. The PMBD score comprised 3 parameters identified by binary logistic regression analysis: paraspinal muscle endurance and morphology (PMEM) score, L1 vertebral body computed tomography Hounsfield Units value (L1CT), and age. The statistical weights of each parameter were created by rounding odds ratios (OR) to the nearest integer. The predictive performance of the PMBD score was evaluated by the area under the receiver operating characteristic curve (AUC). RESULTS: 53 patients (20.7%) experienced mechanical complications. The PMBD score ranged from 0 to 4. Patients with higher PMBD score exhibited higher rates of mechanical complications (P<0.001). Binary logistic regression revealed that the PMBD score was an independent factor of mechanical complications (P<0.001). The AUC of the score was 0.818, significantly higher than PMEM score (AUC=0.761, P<0.05), L1CT (AUC=0.690, P<0.05), and age (AUC=0.634, P<0.05). Sensitivity of PMBD was 0.714 (30/42) and specificity was 0.822 (175/213). In terms of the PMBD categories, patients were categorized as low (0-1 score), moderate (2 score), high risk (3-4 score) with a progressive complications rate (7.0%, 31.1%, and 62.5%, P<0.001). CONCLUSION: The PMBD score was a practical assessment tool integrating muscle and bone density to predict mechanical complications after PLIF, with a superior predictive performance compared to previous evaluation methods. Surgeons could utilize the PMBD score for preoperative risk stratification and might formulate individualized surgery procedure.