Are the take-off and landing phase dynamics of the volleyball spike jump related to patellar tendinopathy?

Objective: The causal mechanism of the chronic sports injury patellar tendinopathy is not well understood. The aim of the present study was to compare ankle and knee joint dynamics during the performance of the volleyball spike jump between healthy volleyball players (n = 8) and asymptomatic volleyball players with previous patellar tendinopathy (n = 7).
Design: Cross-sectional.
Methods: Inverse dynamics were used to estimate ankle and knee joint dynamics. From these multiple biomechanical variables, a logistic regression was performed to estimate the probability of the presence or absence of previous patellar tendinopathy among the volleyball players studied.
Results: Several biomechanical variables improved the prediction of the presence or absence of previous patellar tendinopathy. For landing, ankle plantar flexion at the time of touch-down, and knee range of motion during the first part of impact, and for take-off, loading rate of the knee extensor moment during the eccentric countermovement phase of take-off were predictive. As interaction effects, the presence or absence of previous patellar tendinopathy were correctly predicted by ankle and knee range of motion during the first part of impact, by loading rate of the knee extensor moment during the eccentric phases of take-off and landing, and by knee angular velocity during the eccentric phases of take-off and landing.
Conclusion: Smaller joint flexion during the first part of landing impact , and higher rate of knee moment development during the eccentric phases of the spike-jump landing sequence, together with higher knee angular velocities, might be risk factors in the development of patellar tendinopathy in volleyball players.