Exploring Lower-Limb Joint Work in Single-Leg Forward-to-Vertical Jumps: A Case-Control study of Osgood-Schlatter and Healthy Adolescents

Introduction: Osgood-Schlatter is a prevalent knee-pain condition in sports-active adolescents. This study examines whether lower-extremity joint work differ during a single-leg forward-to-vertical (SLFV) jump between Osgood-Schlatter cases and matched pain-free controls, and the potential effects of induced fatigue.

Materials and Methods: In this exploratory study, participants performed SLFV jumps before and after a 5-minute fatigue-inducing protocol. Joint work was calculated for the foot-ground-contact phase between the forward-jump and subsequent vertical-jump. Pain was evaluated using a 0-10 numerical rating scale (NRS).

Results: Twenty-four participants were included. Pain increased for cases during fatigue (+1.28NRS). Pre-fatigue, the case group exhibited lower total concentric and eccentric joint work compared to the controls. The knee absorbed the highest amount of eccentric work in both groups, but notably the case group displayed a greater contribution of knee joint work (~4%), but lower ankle joint work, compared to controls. During fatigue, the case group reduced the total amount of concentric and eccentric joint work, but there were no changes in joint work distribution. Joint work and distribution were largely unchanged for the control group during fatigue.

Conclusion: Small group-differences in joint work and eccentric knee joint work contribution were observed between Osgood-Schlatter cases and controls pre-fatigue. Osgood-Schlatter cases displayed lower total joint work during fatigue, probably due to increased knee pain. These findings suggest that lower-limb joint work does not fully explain the propensity for Osgood-Schlatter-related pain during sports participation. Nevertheless, well-powered studies should investigate the association between specific movement characteristics and the development of Osgood-Schlatter-related pain.