Causal relationship between osteoporosis, bone mineral density, and osteonecrosis: a bidirectional two-sample...

Area of Science:

• Orthopedics
• Genetics
• Epidemiology

Background:

• Osteonecrosis (ON) involves bone cell death from poor blood supply, causing structural damage.
• Osteoporosis (OP) reduces bone density, increasing fracture risk.
• Both ON and OP share risk factors like corticosteroid use and smoking.

Purpose of the Study:

• To investigate the causal links between osteoporosis (OP), bone mineral density (BMD), and osteonecrosis (ON).
• Utilized a bidirectional two-sample Mendelian randomization (MR) approach.

Main Methods:

• Employed genome-wide association study (GWAS) data for OP and ON from the FinnGen database.
• Used BMD data from the Genetic Factors for Osteoporosis (GEFOS) consortium.
• Applied inverse-variance weighted (IVW), MR-Egger, and weighted median methods for causal inference, with sensitivity analyses.

Main Results:

• Osteoporosis (OP) showed a significant positive causal effect on osteonecrosis (ON) (OR=1.223, P=0.025).
• No significant causal relationships were found between BMD and ON, or between ON and OP/BMD.
• Sensitivity analyses confirmed the robustness of findings, indicating no significant heterogeneity or pleiotropy.

Conclusions:

• Provides evidence for a unidirectional causal link: OP increases ON risk.
• Suggests early OP detection and management may reduce ON incidence.
• Highlights that factors beyond BMD, potentially vascular health, are critical in ON development.