Effects of body orientation and direction of movement on a knee joint angle reproduction test in healthy subjects: an experimental study

Background: Joint position sense test assess patient mobility and proprioceptive ability. Yet, application used under different conditions may biases reproduction error resulting in different therapeutic consequences.
Objective: To investigate knee angle reproduction test under different test conditions.
Methods: 25 healthy subjects (mean ± SD, age = 25 ± 2 years, activity level: 9 ± 2 training hours/week) performed knee angle reproduction test in the sitting and prone position, while changing the knee angle starting (i) from flexion and (ii) extension, (iii) inducing vibration on the semitendinosus tendon.
Results: Absolute mean knee angle reproduction error showed significant difference for body position and vibration (Position: 95% CI 0.71 to 2.32; p < 0.001. No Vibration & Vibration: 95% CI -1.71 to -0.12; p = 0.027). Relative knee angle reproduction error was significant different in all conditions (No Vibration & Vibration: 95% CI -3.30 to -0.45; p= 0.010. Body orientation: 95% CI 1.08 to 3.93; p < 0.001. Direction of movement: 95% CI 0.56 to 3.41; p = 0.007).
Conclusion: Body orientation and movement direction influence the resulting knee angle reproduction error in healthy subjects. Practitioners are advised to use standardised test procedures when comparing different within- and between-patient results. Trial registration: DOI 10.17605/OSF.IO/AFWRP.