Osteoporotic thoracolumbar spine fractures in the elderly: alterations in GNRI and BMP-2 in delayed union and associated factors

Objective: To investigate the alterations in the Geriatric Nutritional Risk Index (GNRI) and bone morphogenetic protein 2 (BMP-2) levels and identify associated factors in older adults with delayed union of osteoporotic thoracolumbar spine fractures.

Methods: From June 2021 to June 2023, 139 elderly patients with osteoporotic thoracolumbar spine fractures were selected and divided into a delayed group and a normal group according to the fracture healing status at 6 months postoperatively. GNRI and BMP-2 levels were assessed in both cohorts. Receiver operating characteristic (ROC) curves were used to determine the predictive value of GNRI and BMP-2 for delayed union. Multivariate Logistic regression was utilized to identify risk factors associated with delayed union after surgery for osteoporotic thoracolumbar spine fractures. Pearson correlation analysis was conducted to explore the relationships among independent risk factors. Finally, the Generic Quality of Life Inventory-74 (GQOL-74) was employed to assess the quality of life in both groups.

Results: At 6 months post-surgery, 41 of the 139 patients had delayed union and were classified into the delayed group, while 98 cases achieved fracture healing and served as the normal group. The delayed group exhibited obviously reduced GNRI and BMP-2 levels than the normal group. ROC curve analysis indicated that the areas under the curve (AUCs) of GNRI, BMP-2, and their combination for predicting delayed union were 0.826, 0.803, and 0.883, respectively. A higher recovery rate of the injured vertebra height (OR = 1.456, 95% CI: 1.232-1.722, P < 0.001), a lower GNRI (OR = 0.590, 95% CI: 0.444-0.782, P < 0.001), and a lower BMP-2 level (OR = 0.909, 95% CI: 0.850-0.971, P = 0.005) were independent risk factors for delayed union in elderly patients undergoing surgery for osteoporotic thoracolumbar spine fractures. Pearson correlation analysis showed a negative correlation between the recovery rate of the injured vertebra height and GNRI (r = -0.640) as well as BMP-2 (r = -0.614), and a positive correlation between GNRI and BMP-2 (r = 0.751). Although the postoperative quality of life in the delayed group significantly enhanced, it remained significantly lower than that in the normal group.

Conclusions: Delayed union after surgery in elderly patients with osteoporotic thoracolumbar spine fractures is strongly associated with preoperative levels of GNRI and BMP-2. The recovery rate of the injured vertebra height, GNRI, and BMP-2 are independent risk factors for delayed fracture healing. Delayed healing of osteoporotic thoracolumbar spine fractures in the elderly negatively affects the improvement of patients' quality of life.