The measurement of the knee joint position sense – Different test settings affecting the resulting angle reproduction error

Background: The return to sports of an athlete after injury is a multifaceted and often challenging decision, made daily by clinicians, physiotherapists, and coaches. One important criterion is the state of the proprioceptive feedback mechanisms, which are required to determine an adequate movement pattern. Joint position sense tests, assessing a patient's mobility and proprioceptive ability, play a crucial role in clinical evaluations. However, ones has to note that the application of these tests under different conditions can introduce biases in the reproduction error. This potentially leads to varying therapeutic consequences and influences further treatment decisions.

Objective: The aim of the present study was to investigate the knee angle reproduction test as a measurement of joint position sense under varying test conditions, such as different body orientations and movement directions.

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: 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). 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).

Conclusion: When examining healthy subjects, it is important to consider how body orientation and movement direction can impact the knee angle reproduction error. Furthermore, considering the economic health aspects, the choice of test conditions should be based on the participants’ resources to perform their best results To ensure a valide comparisons of results both within and between patients, practitioners are advised to follow fully standardized test protocols. Trial registration: DOI 10.17605/OSF.IO/AFWRP