The kick motion analysis of adolescent male soccer players with Osgood-Schlatter disease

OBJECTIVES: Osgood-Schlatter disease (OSD) is an injury during adolescence, in which inflammation occurs in the epiphyseal cartilage of the tibial tubercle by repeated traction of patellar tendon. OSD is associated with more in sports that involve jumping, kicking, and running, such as soccer. However, whether the kick motion of adolescent soccer players is related to onset of OSD remains unclear. The purpose of this study was to clarify the characteristics of kick motion in adolescent soccer players who developed OSD prospectively, using three-dimensional motion analysis system. METHODS: A total of 29 Japanese adolescent male soccer players who were 12 years old (Hight 153.1 ± 6.9cm, Bodyweight 42.8 ± 7.0kg) joining the same soccer team were followed over a half year period. The team is a town recreation league team. At the baseline, all players went through the medical examination, ultrasonography of tibial tubercle and measurement of real-time kick motion using a three-dimensional motion analysis system (Qualisys track manager, Qualisys AB., Sweden). The three-dimensional angle of the lumbar spine, pelvis, hips, knees, ankles of both legs, the position of supporting leg and center of mass (COM) were calculated by 65 spherical markers on each anatomical landmark. COM was adjusted dividing by height. The ball speed, kicking time, angular velocity and angular acceleration were also calculated. The data of each phase was collected for the following eight events: foot contact, toe off, maximum hip extension, maximum knee flexion, ball impact, maximum hip flexion of kicking leg, and foot contact, maximum knee flexion of supporting leg. Phase duration was calculated as a percentage of the kick motion. The muscle tightness test of bilateral lower limbs (Iliopsoas, Hamstrings, Quadriceps, Gastrocnemius, Soleus muscle) were measured at the baseline and the follow-up. The participants were followed six months later, and OSD was diagnosed by tenderness and ultrasonography findings of the tibial tubercle and were divided into two groups: presence of OSD on supporting leg; OSD and absence of OSD; CON. All the factors calculated by the kick motion analysis at the baseline and the development of muscle tightness of bilateral lower limbs between OSD and CON were compared by using the unpaired t-test. Players who were diagnosed as OSD at the baseline (n=6) were excluded from the analysis. RESULTS: There were 10 players of OSD and 13 players of CON. The growth of height, muscle tightness, ball speed, kicking time, phase duration in OSD were not different from CON. The sagittal translation of COM in OSD was significantly smaller than CON(p<0.05) before the ball impact phase. The knee angular acceleration of supporting leg was significantly larger in OSD(p<0.05) between the phase supporting leg lands and the flexion angle of its knee reaches the peak before the ball impact. The lateral bending angle of the pelvis toward the supporting leg in OSD was significantly smaller(p<0.05), and the maximum hip extension angle of kicking leg, lumbar rotation angle, kicking leg’s knee angular velocity and acceleration at the ball impact were smaller in OSD(p<0.1). CONCLUSION: The kick motion with small translation of COM before ball impact was associated to onset of OSD. OSD also showed smaller range of motion in proximal joints to the knees compared with CON. The large knee angular acceleration of supporting leg towards maximum knee flexion was found in OSD, which may increase the traction of quadriceps muscle to the tibial tubercle.