Background A multitude of risk factors have been reported to increase an athlete's risk of developing jumper's knee. An overuse injury definition has been cited as more sensitive in capturing knee injuries when compared to a time-loss injury definition. To date, risk factors for jumper's knee have not been assessed for the development of knee problems captured by an overuse injury definition.
Objective To assess a multitude of potential intrinsic risk factors for jumper's knee in volleyball players.
Design Prospective Cohort.
Setting Collegiate and national team training facilities.
Patients (or Participants) Sixty elite adult male volleyball players were recruited from collegiate and national team programs in Canada.
Interventions (or Assessment of Risk Factors) Participants completed risk factor assessments at the commencement of the season including: vertical jump ability (cm), weight bearing ankle dorsiflexion range (degrees), dynamic balance (cm), dynamic knee alignment (degrees) and landing mechanics (degrees).
Main Outcome Measurements Self-reporting knee problems utilizing an overuse injury questionnaire collected via short message service (SMS) was completed prospectively over one season. Substantial knee problems were identified and logistic regression was used to estimate odds ratios for each risk factor independently.
Results The season prevalence of knee problems was 75.0% (95% CI: 62.2 to 84.6) and the incidence proportion of those rated as substantial was 30.0% (95% CI: 19.5 to 43.1). The SMS system of tracking overuse injuries demonstrated 98.2% completeness. No single risk factor was found to predict substantial knee problems. All odds ratios were close to unity with narrow confidence intervals (0.91–1.07) and p>0.05.
Conclusions A more sensitive capture of overuse knee injuries did not result in the identification of distinct risk factors for the development of jumper's knee. These findings bring question to the utility of field based pre-season risk factor assessment for the identification of at risk athletes.