Risk factors associated with lower extremity stress fractures in runners: a systematic review with meta-analysis

BACKGROUND: Stress fractures are common overuse injuries with up to 95% occurring in the lower extremities. Among runners, stress fractures account for 15-20% of all musculoskeletal injuries. PURPOSE: We systematically reviewed and critiqued the evidence regarding risk factors associated with increased risk of lower extremity stress fractures in runners. STUDY DESIGN: Systematic review. METHODS: A systematic, computerised literature search of Medline, Embase, PubMed, SPORTDiscus, and CINAHL databases (from database inception through 9 January 2014) using keywords related to risk factors and stress fractures. This systematic review with meta-analysis utilised the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for the search and reporting phases of the study. Inverse variance meta-analyses, using a random effects model were used to summarise ORs. RESULTS: 8 articles met the inclusion criteria; 7 were considered low risk. 4 articles qualified for meta-analysis. Results of the meta-analysis identified previous history of stress fracture and female sex as the primary risk factors for future stress fracture with a pooled OR of 4.99 (95% CI 2.91 to 8.56; p<0.001; I(2)=0%) and 2.31 (95% CI 1.24 to 4.29; p<0.01; I(2)=0%), respectively. CONCLUSIONS: Currently, only previous history of stress fracture and female sex are risk factors for lower extremity stress fractures strongly supported by the data.