Risk Factors for Patellofemoral Pain in the Military: Systematic Review with Meta-Analysis.

Background: The main cause for attrition of military training is musculoskeletal injuries to the knee, such as patellofemoral pain (PFP).

Objective: The purpose of this systematic review was to identify which factors increase the risk of occurrence of PFP in military personnel.

Study design: Systematic review with meta-analysis.

Data sources: Searches were performed in Medline/PubMed, CINAHL, Embase, SPORTDiscus, Web of Science, Scopus, and OpenGray.

Study selection: We included studies that were prospective cohorts including military personnel and had at least one variable assessing a risk factor for PFP.

Data extraction: Extraction was performed by the same two independent evaluators and the data was separated between the military personnel who developed PFP and those who did not.

Data synthesis: 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%. We found moderate evidence that isokinetic knee extensor weakness predicts PFP in the military (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 extensor strength and a greater 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.