This study aimed to investigate the influence of patella height on the thickness and electrical activities of quadriceps muscles as well as postural stability. Therefore, it is needed to determine whether the changes in patella height is associated to structural and functional changes in the knee joint.
A total of one hundred male volunteers aged 20 to 35 years were recruited in present study, and their patellar height was examined from eighty-two participating subjects. Patella height was estimated by measuring the LT/LP ratio of patella length (LP) and patella tendon length (LT) using a distal vernier caliper (M500-150M, Hando, Cheonan, Korea) on the dominant leg. Thickness from patella tendon, quadriceps femoris tendon and rectus femoris (RF) muscle were measured using ultrasound images. Muscle activities of rectus femoris (RF), vastus lateralis (VL) and medialis (VM) muscles were analyzed by surface electromyography (sEMG, 4D-MT, 2EM sensor, Relive, Korea) during isometric knee extension. Also, postural stability was measured via Biodex balance system (BBS, Biodex Medical Systems Inc, New York, USA) under the eyes-opened and closed conditions. This study was approved by the Institutional Review Board of the College of Health and Welfare, Woosong University (approval No. 1041549-210413-SB-118), and all subjects were briefed on the study and provided written informed consent prior to participation.
It was confirmed that patellar height was associated with structural and functional factors. LT/LP ratio showed a moderate positive correlation (r=.403) with thickness of RF muscle (p.01), and mild positive associations with overall stability index (r=.230) and medial-lateral stability index (r=.276) under the eyes-closed condition (p.05). However, sEMG muscle activities of RF (r=-.283) and VM (r=-.283) had mild negative relationship with patellar height, respectively (p.05).
These results demonstrated that the changes in patellar height can affect the quadriceps muscle thickness, sEMG activities and postural stability. RF muscle thickness was increased and RF and VM muscle activities were decreased, also postural stability was reduced as the patella showed feature of alta.
Patellar height is vulnerable to various factors, which can induce the secondary damage of knee joint. Thus, these results would support understanding of knee joint pathologies caused by changes in patella height, and provide basic evidence needed for knee joint rehabilitation.
muscle thickness and activities
postural stability
