Investigating the validity of low-cost technologies for the assessment of jumping-based performances in people with patellofemoral pain.

Background: Patellofemoral pain (PFP) is prevalent across various age and activity groups and poses a risk for developing patellofemoral osteoarthritis. Since load on the patellofemoral joint is greatest during jumping manoeuvres, validating affordable measuring instruments to extract jumping-related variables is important for guiding rehabilitation. Objectives: To evaluate the validity of low-cost devices against 'gold standard' force plates during jumping and to quantify differences in kinematic variables between low-cost devices and across different groups (PFP vs. Control). Methods: A repeated-measures design of between- and within-subject factors was used. Thirty-two participants (Control: n=16; PFP: n=16) volunteered for the study. Single leg drop jump variables were validated using force plates and 3D motion capture (mocap) as the criterion standards against the MyJump2 and Tracker software applications as the reference standards. Results: Good-to-excellent correlations were evident across all variables when comparing the force plates to MyJump2 (r=0.83-0.97) and Tracker (r=0.83-0.89) applications. Tracker was not significantly different from force plates or mocap for jump height (p=0.130) and flight time (p=0.230), but overestimated contact time for both groups (control group [p<0.001] and PFP group [p=0.007]). MyJump2 was not significantly different from force plates regarding contact time in the PFP group (p=0.500) but showed significant differences for the other parameters (p<0.001). Conclusion: Both Tracker and MyJump2 applications show promise as alternatives to laboratory-grade equipment, with MyJump2 emerging as the top low-cost tool.