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

Area of Science:

• Kinesiology and Biomechanics
• Neuroscience
• Clinical Assessment

Background:

• Proprioception, the sense of body position, is crucial for motor control.
• Understanding how factors like joint angle, load, and contraction type affect proprioception is limited.
• Clinically feasible methods for assessing proprioceptive acuity are needed.

Purpose of the Study:

• To implement smartphone technology for evaluating knee active joint position sense.
• To determine the influence of joint angle, joint loading, and quadriceps contraction type on proprioception.

Main Methods:

• A crossover study involving 20 healthy university participants.
• Utilized a smartphone accelerometer application to measure joint position sense accuracy.
• Analyzed effects of load (weighted/unweighted), contraction type (concentric/eccentric), and joint position (20°/70°).

Main Results:

• Eccentric contractions resulted in significantly greater proprioceptive error (0.50°) compared to concentric contractions (P = .02).
• A significant interaction showed increased error (0.98°) during eccentric contractions at the 20° joint position (P = .03).

Conclusions:

• Quadriceps eccentric contractions, particularly at 20°, significantly impair proprioceptive sensitivity.
• Smartphone-based assessment offers a viable clinical tool for evaluating knee proprioception.
• Findings suggest potential differences in neural feedback mechanisms between concentric and eccentric muscle actions.