Jumper's Knee: A Prospective Evaluation of Risk Factors in Volleyball Players Using a Novel Measure of Injury.

OBJECTIVES:To examine potential intrinsic risk factors that may contribute to the onset of jumper's knee in elite level-male volleyball players. DESIGN:Prospective Cohort Study. SETTING:Varsity and National team volleyball gymnasiums. PARTICIPANTS:Sixty elite adult male volleyball players from Canada. ASSESSMENT OF RISK FACTORS:Players completed a series of risk factor assessments at the commencement of their seasons, including vertical jump (cm), ankle dorsiflexion range (degrees), dynamic balance (normalized distance reached; cm), dynamic knee alignment (degrees), and landing mechanics (degrees). MAIN OUTCOME MEASURE:Self-reported knee problems, captured via short message service. RESULTS:Knee problem prevalence was 75% [95% confidence intervals (CIs): 62.2-84.6] and the incidence rate for substantial injuries over the study period was 30 injuries/100 players/season (95% CI: 19.5-43.1). No risk factor was found to significantly predict the future occurrence of developing jumper's knee. The odds ratios were close to unity (range: 0.94-1.07) with narrow confidence intervals and P > 0.05. CONCLUSIONS:A more sensitive capture of overuse knee problems did not result in the identification of distinct risk factors for the development of jumper's knee. These findings highlight a lack of available methodology to accurately assess risk factors for overuse injuries.