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

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.