Ground reaction force analysis in flexible and rigid flatfoot subjects.

BACKGROUND: Flatfoot is a structural and functional deformity of the foot that might change ground reaction force variables of gait. Evaluating the components of ground reaction force in three dimensions during gait is considered clinically important. This study aimed to investigate the components of ground reaction force, impulse, and loading rate during gait in people with flexible and rigid flatfoot compared to healthy subjects. 20 young women with flatfoot in two experimental groups (10 with rigid flatfoot and 10 with flexible flatfoot) and 10 healthy women in the control group participated in this study. Ground reaction force components during gait were measured using two force plates. The peak of ground reaction forces, impulse, and loading rate were then extracted. Data were processed and analyzed using MATLAB and SPSS software. One-way ANOVA with a significant level (P˂0.05) was used for statistical analysis. The results showed that peak braking force was higher in the rigid flatfoot group than in the control group (p = 0.016) and the flexible flatfoot group (p = 0.003). The posterior force loading rate was significantly higher in the rigid flatfoot group than in the flexible flatfoot group (P = 0.04). There was no significant difference in vertical loading rate between groups (P˃0.05). Since the maximal posterior ground reaction force was higher in the subjects with rigid flatfoot than in those with flexible flatfoot and healthy subjects, the increase in posterior ground reaction force is associated with an increase in anterior shear force at the knee.

Evaluation of the Asymmetry of Leg Muscles Forces in the Subjects with Anterior Cruciate Ligament Reconstruction.

Running asymmetry has not been assessed among patients with anterior cruciate ligament (ACL) deficiency. The aim of this study was to evaluate the spatiotemporal and muscle force asymmetry indexes in the subjects with ACL reconstruction (ACLR) compared with normal subjects. Eight individuals with a reconstructed ACL and eight individuals with intact ACLs were participated in this study. A Vicon motion analysis system and two Kistler force plates were used to record data. Muscle forces analysis was done by the use of OpenSim software. The results of this study showed that ACLR group had a significant weakness in hip abductor, extensor, and adductor muscles of the affected limb compared with healthy subjects (p < 0.05). In ACLR group, asymmetry of gluteus minimus muscle force was significantly greater than that of healthy group (p = 0.04). After the reconstruction of the ACL, there is still a significant asymmetry in muscle force as well as a reduction in force production of ACLR group especially in reconstructed side which put a person at high risk of reinjuries. Thus, strengthening of these muscles on the affected side to increase running performance of ACLR group is recommended.