Objective: The aetiology of patellar tendinopathy ( jumper's knee) remains unclear. To see whether landing strategy might be a risk factor for the development of this injury, this study examined whether landing dynamics from drop jumps differed among healthy volleyball players ( CON) and volleyball players with a jumper's knee. The patients with jumper's knee were divided into an asymptomatic group with a previous jumper's knee (PJK) and a symptomatic group with a recent jumper's knee (RJK).
Methods: Inverse dynamics analyses were used to estimate lower extremity joint dynamics from 30, 50 and 70 cm drop jumps in the three groups ( CON, n = 8; PJK, n = 7; RJK, n = 9). A univariate repeated measures analysis of variance was used to compare the different landing techniques.
Results: Data analysis of the landing dynamics revealed that PJK showed higher knee angular velocities ( p <0.01), and higher ankle plantar flexion moment loading rate ( p <0.01). Furthermore, strong tendencies of higher loading rate of vertical ground reaction force ( p = 0.05) and higher knee extensor moment loading rate ( p = 0.08) were found compared with CON. Higher values for peak knee moment, peak knee power and knee work ( all p <0.01) were found for CON compared with RJK. The comparison of the two jumper's knee groups yielded higher knee angular velocities ( p <0.01), together with higher ankle plantar flexion and knee extensor moment loading rate ( p <0.01 and p <0.05, respectively).
Conclusion: Where RJK used a landing technique to avoid high patellar tendon loading, PJK used a stiffer landing strategy, which may be a risk factor in the development of patellar tendinopathy.