Multifactorial prediction of mechanical complications after lumbar fusion using bone quality and turnover markers

PURPOSE: To evaluate the predictive value of preoperative bone health indices including T-score, bone mineral density (BMD), Hounsfield units (HU), and serum bone turnover markers for postoperative mechanical complications following lumbar fusion surgery. METHODS: This retrospective study analyzed prospectively collected data from 120 patients who underwent lumbar fusion with pedicle screw instrumentation between August 2021 and June 2024. Preoperative assessments included dual-energy X-ray absorptiometry (DEXA)-derived BMD and T-scores, computed tomography-derived HU values, and serum bone turnover markers including procollagen type I N-terminal propeptide (P1NP) and tartrate-resistant acid phosphatase type 5b (TRACP-5b). Mechanical complications were evaluated radiographically at ≥ 12 months postoperatively. Receiver operating characteristic (ROC) curve analyses were performed for individual parameters, and multivariable logistic regression was used to identify independent predictors. RESULTS: Mechanical complications occurred in 40 patients (33%). In univariate analysis, patients with complications were significantly older and had lower femoral BMD and T-scores and higher P1NP levels (all p < 0.05). ROC analysis demonstrated modest predictive ability for femoral T-score (AUC = 0.688) and BMD (AUC = 0.681). In multivariable logistic regression, TRACP-5b (OR = 1.02, p = 0.042) and the number of fused levels (OR = 5.24, p = 0.001) were associated with complications. A multivariate model combining significant variables yielded an AUC of 0.830, indicating good overall discrimination. CONCLUSIONS: Preoperative T-score, BMD, and HU values alone showed limited predictive accuracy for mechanical complications after lumbar fusion. However, integrating serum bone turnover markers and surgical factors substantially improved predictive performance. A multifactorial preoperative assessment incorporating bone density, metabolic, and mechanical parameters may better stratify risk and guide surgical planning in patients with poor bone quality.