Abstract
BACKGROUND: Anterior cruciate ligament injury can disrupt one's mechanoreceptors and result in decreased proprioception such as joint position sense and ultimately altered motor function. The application of localized vibration has been used to investigate the integrity of the sensorimotor system and the mechanisms of quadriceps function after anterior cruciate ligament injury and reconstruction. The purpose of the study is to evaluate joint position sense with and without vibration and compare among anterior cruciate ligament reconstructed, contralateral, and control limbs. METHODS: Fourteen subjects with anterior cruciate ligament reconstruction (8 males and 6 females) and fourteen control subjects (7 males and 7 females) participated in the study. Subjects sat on an isokinetic dynamometer chair with localized vibration strapped on the quadriceps tendon while visual and auditory cues were removed. Subjects were asked to remember an active target position and replicate that position actively. The absolute difference between the target and replicated trial was used as joint position sense. There were three trials at three target positions (15, 45, and 75 degrees of knee flexion) with and without vibration. The order of testing conditions was randomized. One-way analysis of variance or non-parametric equivalent (Kruskal-Wallis test) was used to compare among limbs. Significance was set at P < 0.05 a priori. FINDINGS: There were no significant joint position sense differences among anterior cruciate ligament reconstructed, contralateral, and control limbs with or without vibration (P = 0.207-0.914). INTERPRETATION: There are several potential reasons for the current findings: vibration-induced post effect, locations of vibration, types of vibration, and rehabilitation status. Future studies should expand the current investigation and explore both sensory and motor functions in anterior cruciate ligament reconstructed subjects.