gms | German Medical Science

Objective: Os trigonum syndrome, known as posterior ankle impingement syndrome, is caused by repetitive stress from ankle plantar flexion due to kicking in soccer players. Our recent study showed that the angle of maximal ankle plantar flexion angle on ball impact does not exceed that of passive plantar flexion (2010). The purpose of this study was to demonstrate a gradual change in the angle of maximal plantar flexion during repetitive instep kick. We hypothesized that repetitive instep kicking increases the maximal ankle plantar flexion angle on ball impact, by causing fatigue of the tibialis anterior and repetitive stress of the periarticular tissues.

Material/Methods: Eight male university soccer players participated in this study. The subjects performed 11 sets of 3 maximal instep kicks. Among each sets, they repeated 10 maximal instep kicks. Before and after the experiments, isometric muscle strength of ankle dorsal flexion and passive plantar flexion were measured. The movements of the kicking legs on ball impact were captured using 3 high-speed cameras (4 Assist, Japan) at 200 Hz. The direct linear transformation method was used with a digitizing system (Ditect, Japan) to obtain 3D coordinates. One-way ANOVA was used to compare the maximal ankle plantar flexion angle on ball impact among the sets. Student’s t-test was used to compare the isometric muscle strength of ankle dorsal flexion and the passive plantar flexion. P<0.05 was considered significant. Data analyses were performed using SPSS (IBM, Japan).

Results: There were significant differences in the isometric strength of ankle dorsal flexion (272.9 ± 44.3N vs. 182.1 ± 59.8N) and the angle of passive plantar flexion (50.6 ± 6.4° vs. 54.1 ± 6.0°) between the measurements taken before and after the experiences. Figure 1 [Fig. 1] shows the maximal ankle plantar flexion angle on ball impact. The largest angle was 43.9 ± 16.8° (set 4) and the smallest angle was 41.2 ± 13.3° (set 11). There were no significant differences among the sets.

Conclusion: Our results suggested that fatigue of the tibialis anterior and repetitive stress of the periarticular tissues occur after the repetitive instep kick. However, repetitive instep kick did not increase the maximal ankle plantar flexion angle on ball impact. This finding did not support our hypothesis. Ankle plantar flexion on ball impact might have been avoided by the compensatory change in the way of kicking, i.e., the foot inversion and eversion movement.