Background Patellar tendinopathy (PT) is a common injury in sports with repetitive landing tasks such as volleyball. Impaired landing biomechanics are assumed to play a role in the development of this overuse injury but evidence from prospective research is lacking.

Objective The aim of the study was to investigate jump-landing biomechanics associated with knee loading as risk factors for PT in volleyball players during both sport-specific and generic jump-landing tasks.

Design Prospective cohort study

Setting Biomechanical lab, Belgian competitive volleyball teams

Patients or Participants 79 healthy male volleyball players

Assessment of Risk Factors Pre-season, three-dimensional knee joint kinematics and kinetics were collected during three different jump-landing tasks (spike jump, block jump and drop vertical jump). During follow-up, injury data were collected by using a weekly questionnaire and a 3-monthly retrospective control questionnaire.

Main outcome measurements Univariate cox regression with competing risk analysis was used to identify significant risk factors for PT (p<0.05).

Results Ten volleyball players developed PT during the follow-up period of one season (13%). No kinematic risk factors for PT were identified. However, increased concentric knee joint work during all jump-landing tasks (block jump HR= 16.5, p=0.012; spike jump HR= 6.2, p=0.033; drop vertical jump HR= 8.6, p=0.036) and increased eccentric knee joint work during the block jump (p=0.04) are predictive parameters to develop PT.

Conclusions Knee joint kinematics during jump landing do not seem to be a risk factor for PT. Interestingly, higher concentric knee joint work during volleyball-specific and generic jump-landing tasks and higher eccentric knee joint work during block jump are risk factors to develop PT. Large-scale studies are needed to confirm if adaptation or modification of these defined risk factors are effective to reduce injury risk.