Abstract
This study was designed to compare proprioception and postural stability in patients with acute (time from injury ≤ 3 months) and chronic (time from injury > 3 months) ACL tears, and to evaluate the correlation between time interval after ACL injury and proprioception. Thigh muscle strength, postural stability, and joint position sense were compared in 48 patients with acute ACL tears and in 28 with chronic ACL tears. Maximal torque (60°/sec) of the quadriceps and hamstring was evaluated using an isokinetic testing device. Postural stability was determined from the anterior-posterior (APSI), medial-lateral (MLSI), and overall (OSI) stability indices using stabilometry. Joint position sense was also tested by reproduction of passive positioning (RPP). Muscle strengths and stability indices on both the involved and uninvolved sides were similar in the acute and chronic ACL tear groups. RPP on the involved side was significantly greater in the chronic than in the acute ACL tear group (7.8° vs. 5.6°, P = 0.041). Two of three stability indices (APSI, OSI) and RPP were significantly greater on the involved than the uninvolved side in the chronic ACL tear group.
Highlights
The femoral and tibial attachment sites of the anterior cruciate ligament (ACL) contain mechanoreceptors such as the Pacinian corpuscles, Ruffini endings, and Golgi tendon organ-like corpuscles,[1, 2] all of which play a role in proprioception
Patients who underwent surgery less than 3 months after injury were categorized as having acute ACL tears, whereas those who underwent surgery after 3 months were categorized as having chronic ACL tears
The test-retest reliabilities for postural stability were good for overall (ICC = 0.76), anterior-posterior (ICC = 0.77), and medial-lateral (ICC = 0.75) stability indices, as well as for reproduction of passive positioning (RPP) (ICC = 0.78)
Summary
The femoral and tibial attachment sites of the anterior cruciate ligament (ACL) contain mechanoreceptors such as the Pacinian corpuscles, Ruffini endings, and Golgi tendon organ-like corpuscles,[1, 2] all of which play a role in proprioception. ACL tears create mechanical instability, they may impair proprioception, including postural stability, because disruption of the ACL may lead to a lack of afferent sensory input from mechanoreceptors to the central nervous system.[3,4,5] Several studies have shown a significant loss in proprioception in ACL-deficient knees.[6,7,8] Single limb stance postural stability has been reported to be impaired in patients with isolated ACL tears.[9, 10]. Proprioception, including postural stability, may be influenced by a variety of factors, including age, muscle weakness, level of physical activity, and previous injury to the lowerextremities.[11,12,13] In addition, elapsed time from the injury may affect proprioception and PLOS ONE | DOI:10.1371/journal.pone.0139038.
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