Risk Factors for Patellofemoral Pain in Military: A Systematic Review with Meta-Analysis
Knee Joint, Anterior Knee Pain, Relative Risk, Military Force, Naval Medicine.
Background: The main cause for abandonment of military training is musculoskeletal injuries to the knee, with patellofemoral pain (PFP) being one of the leading causes for military career dropout. The identification of risk factors is the first step for injury prevention. The purpose of this systematic review was to identify which factors increase the risk of occurrence of PFP in military personnel. Methods: Searches were performed in Medline/PubMed, CINAHL, Embase, SPORTDiscus, Web of Science and Scopus, from inception to January 2023. We included studies that were prospective cohorts including military personnel and had at least one variable assessing a risk factor for PFP. Meta-analyses were performed using standardized mean differences (SMD) and 95% confidence intervals (95%CI) and the levels of recommendation were determined. Results: From 11 articles, this review grouped 7,518 military personnel, of which 572 developed PFP, characterizing a prevalence of 7.61%. There is moderate evidence that knee extensor weakness predicts PFP in the military, especially if normalized against body mass index and evaluated isokinetically at 60º/s (SMD -0.69, 95%CI -1.02, -0.35). A higher frontal plane knee projection angle (FPKPA) during single-leg squat was also identified as a risk factor for PFP in this population (SMD 0,55, 95%CI 0.14, 0.97) with moderate level of evidence. We found moderate evidence that sex, body mass index, isometric knee extensors strength and isokinetic knee flexors strength do not predict PFP in military personnel. Finally, there is strong evidence that age and body mass do not predict PFP in this population. Conclusions: Deficits in isokinetic knee extensors strength and a high FPKPA are risk factors for PFP in military personnel. Since these are modifiable factors, these aspects should be considered in injury prevention interventions in the military.