Effect of Load, Angle, and Contraction Type on Clinically Assessed Knee Joint Position Sense

Abstract

Context: Proprioception is an individual’s awareness of body position in 3-dimensional space. How proprioceptive acuity changes under varying conditions such as joint position, load, and concentric or eccentric contraction type is not well understood. In addition, a limitation of the variety of techniques to assess proprioception is the lack of clinically feasible methods to capture proprioceptive acuity. The purpose of this study was to implement a readily available instrument, a smartphone, in the clinical evaluation of knee active joint position sense and to determine how joint angle, joint loading, and quadriceps contraction type affect an individual’s active joint position sense. Design: Cross-over study. Methods: Twenty healthy, physically active university participants (10 women and 10 men: 21.4 [2.0] y; 1.73 [0.1] m; 70.9 [14.3] kg) were recruited. Individuals were included if they had no neurological disorder, no prior knee surgery, and no recent knee injury. The participants were given a verbal instruction to locate a target angle and then were tasked with reproducing the target angle without visual or verbal cues. An accelerometer application on a smartphone was used to assess the angle to the nearest tenth of a degree. Three variables, each with 2 levels, were analyzed in this study: load (weighted and unweighted), contraction type (eccentric and concentric), and joint position (20° and 70°). A repeated-measures analysis of variance was conducted to assess the within-subjects factors of load, contraction, and position. Results: A significant difference of 0.50° (0.19°) of greater error with eccentric versus concentric contraction (P = .02) type was identified. In addition, a significant interaction was found for contraction × position, with a mean increase in error of 0.98° (0.33°) at the 20° position when contracting eccentrically (P = .03). Conclusions: Contraction type, specifically eccentric contraction at 20°, showed significantly greater error than concentric contraction. This suggests that, during eccentric contractions of the quadriceps, there may be decreased proprioceptive sensitivity compared with concentric contractions.