Puh U.1, Tkalec J.1, Palma P.2
1University of Ljubljana, Faculty of Health Sciences, Department of Physiotherapy, Ljubljana, Slovenia, 2University of Ljubljana, Department of Physiotherapy, Ljubljana, Slovenia
Background: The knee join proprioception sense can be affected in patients with various musculoskeletal and neuromuscular disorders. To control posture and movement, the brain has to integrate proprioceptive information from mechanoreceptors in joints, muscles and skin, including plantar mehanoreceptors. The knee joint position sense is more accurate when assessed in closed (squat) than in open kinematic chain. Compliant surfaces are commonly used for training of proprioception and assessment of proprioceptive component of balance.
Purpose: The purpose of the study was to compare the knee joint position sense in closed kinematic chain on a firm and compliant surface.
Methods: 30 subjects (19 females and 11 males; mean age: 21.8 ± 2.56 years) with no previous injury or surgical procedures on the dominant leg, participated in the study. They were randomly assigned to one of two groups. Measurements of the knee joint position sense were repeated when subject performed one leg squat on the dominant leg, using an electrogoniometer SG 110 (Biometrics Ltd.) in two conditions. In group 1, the tests were performed on a firm surface first, followed by the compliant surface (Airex Balance Pad); in group 2, the order was opposite. Following a trial to check the understanding of the protocol, the two target angles (15° and 30° of flexion) in the knee joint were assessed in random order from the starting position 0°. For each angle, holding the position for 5 seconds was measured three times. Absolute errors were calculated for a mean difference in target and repeated angle and compared within and between groups, using parametric tests.
Results: Mean absolute errors were greater for 15° than for 30° of flexion on a firm and compliant surface, respectively (4.76 ± 3.82 and 4.27 ± 3.07 vs 3.61 ± 2.61 and 3.74 ± 2.37). However, no statistically significant difference was found between the two surfaces. Comparison between the groups revealed that mean absolute errors decreased in the second testing condition. Difference between the groups was statistically significant (p = 0.02) only for 15° of flexion on a firm surface (group 1: 6.31±4.17 vs group 2: 3.20 ± 2.76).
Conclusion(s): According to the obtained results we concluded that there is no significant difference in knee joint position sense in standing on a firm and compliant surface, but to confirm this study with larger sample is required. It seems that the learning effect has a role. On compliant surface information from joint and skin mechanoreceptors is disturbed, however possible compensatory mechanism for joint position sense in healthy young people, might be the less disturbed information from muscle spindles. This could be an explanation also for lower absolute errors at 30° of flexion as compared to 15°.
Implications: This is one of the first studies investigating the assessment of joint position sense on a compliant surface. Comparison between the firm and compliant conditions might add to understand the proprioceptive mechanisms underlying human movement control, and have an impact to development of physiotherapy outcome measures.
Funding acknowledgements: No acknowledgements for funding, the work was unfunded.
Topic: Human movement analysis
Ethics approval: The study was approved by the Ethics committee, Rupublic of Slovenia.
All authors, affiliations and abstracts have been published as submitted.
