# Knee angle reproduction tests: influences of body orientation, movement direction and limb dominance

## TL;DR

This study shows that knee angle reproduction errors vary based on body position, movement direction, and limb dominance, affecting how joint position sense tests should be interpreted.

## Contribution

The study identifies specific test conditions that influence knee angle reproduction errors in healthy individuals.

## Key findings

- Reproduction errors were greater in the seated position compared to the prone position.
- Using the dominant limb as the reference increased errors in the seated position but not in the prone position.
- Test conditions should be standardized to avoid biased comparisons between knees.

## Abstract

Applying joint position sense tests under different test conditions may introduce
reproduction error bias, which can result in different therapeutic consequences.
This study investigated the effects of body orientation, movement direction, and
limb dominance on the active knee angle reproduction error. Subjects underwent
active contralateral knee angle reproduction tests in a seated versus prone
position, from a starting point of knee flexion versus knee extension, and with
the dominant versus nondominant limb setting the target angle. The test order
was randomly determined for each subject. The primary outcome was the absolute
active knee angle reproduction error (°). The data of 54 healthy subjects
(mean±standard deviation, age: 26±5 years, height: 174±11 cm, body mass:
69.9±14.4 kg, and Tegner activity score: 5.8±1.9) showed that the reproduction
error was greater in the seated position than in the prone position. The use of
the dominant limb as the reference limb was associated with significantly
greater errors in the seated position, but not in the prone position. In
conclusion, directly comparing the results obtained in the prone and seated
positions is not recommended. However, the dominance of the reference limb might
be relevant when testing patients and comparing healthy and injured knees.