Validity and Reliability of a Laser Pointer Device to Assess Knee Proprioception in Healthy and Active Individuals

BACKGROUND AND PURPOSE: Knee proprioception offers valuable information about the state of the knee joint. The most widely used protocol to estimate it is the joint position reproduction (JPR), although the validated instruments for its measurement are expensive and complex. The aim of this study was to estimate the validity and reliability of a laser pointer device to assess knee proprioception in healthy and active subjects. METHODS: A descriptive cross-sectional study. The study was conducted at a Research Laboratory of the Faculty of Physiotherapy, University of Valencia (Spain). Twenty-five healthy and active individuals (mean (SD) age = 27.24 (3.93) years) were assessed. Proprioception measurements were evaluated with 15° and 50° knee flexion in closed kinetic chain (CKC) and open kinetic chain (OKC), respectively, using a laser device and also a digital inclinometer (to validate the first), on two days by two different evaluators. RESULTS: Validity analysis indicated a moderate to strong correlation between the laser pointer device and the digital inclinometer in all the tests (Pearson's correlation = 0.40-0.55 (CKC) and 0.54-0.82 (OCK)). In the OKC 50° knee test, a moderate inter-rater reliability (ICC = 0.54) and a strong intra-rater reliability (ICC = 0.65) was shown, and in the CKC 15° test a strong inter-rater reliability (ICC = 0.62) and moderate intra-rater reliability (ICC = 0.58) was shown. The rest of the tests showed no intra-rater and inter-rater reliability (ICC = 0.10-0.24). DISCUSSION: Though further research is needed, the results suggest that it could be considered as an affordable, simple and effective resource both in research and in clinical practice.