Author(s): RYAN, I., SUTTON, K., RYAN, O., PEARCEY, G., Institution: MEMORIAL UNIVERSITY OF NEWFOUNDLAND, Country: CANADA, Abstract-ID: 2217

INTRODUCTION:
Proprioception plays a critical role in movement control by providing the central nervous system with information about limb position, and force production. Two commonly assessed components of proprioception are the senses of force and position, which rely on overlapping but distinct neural mechanisms. The proprioceptive sense of position primarily relies on afferent input from muscle spindles and joint receptors, whereas the proprioceptive sense of force relies on integrating this sensory feedback with centrally generated motor commands. Disruptions in both senses following anterior cruciate ligament reconstruction (ACLR) potentially contribute to persistent neuromuscular deficits and altered knee function. Although impairments in both have been reported after ACLR, it remains unclear which is affected more. Therefore, the purpose of this study was to determine if the proprioceptive force or position is more impaired in people with ACLR.
METHODS:
Male and female athletes with a history of unilateral ACLR (1.4 +/- 0.95 years post-surgery; age: 19.7 +/- 1.6 years; height: 165 +/- 4 cm; weight: 155 +/- 18 kg) were recruited and compared to an age- and sex-matched healthy control group with no history of knee injury (age: 21.6 +/- 1.3 years; height: 173 +/- 8.6 cm; weight: 74 +/- 17 kg). All testing was conducted about the knee joint using a Humac Norm isokinetic dynamometer. The proprioceptive sense of force was evaluated using submaximal force reproduction tasks, where participants performed target contractions with visual feedback followed by reproduction trials without feedback, relying on perceived effort to match the target. The proprioceptive sense of position was evaluated using a position reproduction task, during which participants moved their leg to a target knee angle corresponding to 60-70% of their maximum knee extension range of motion with visual feedback, followed by an active reproduction of the target position without feedback. Force and position reproduction was quantified using absolute error (accuracy) and constant error (bias), calculated relative to the target force or position. We hypothesized that participants with ACLR would demonstrate greater relative impairment in force sense compared with position sense, reflecting the greater reliance on central motor integration processes.
RESULTS:
Preliminary results showed that people with ACLR had similarly impaired senses of both force (p = 0.0071; d = 0.59) and position (p = 0.0072; d = 0.64) in their injured leg, compared to the uninjured leg, whereas there were no differences in the senses of force (p = 0.51) or position (p = 0.34) between the legs of the healthy controls.
CONCLUSION:
These findings indicate that, following ACLR, there are similar impairments in the proprioceptive sense of force and position, suggesting that proprioceptive deficits may be due to widespread sensory deficits.