Kinematic assessment of paediatric forefoot varus.

Forefoot varus is a static deformity not easy to assess clinically. If left uncorrected, it is thought to affect both the posture of the patient and the kinematics of their lower limbs, and even the spine. Three-dimensional gait assessment could help to confirm forefoot varus diagnosis and provide objective evidence of the functional adaptive mechanisms postulated in the literature. The recently available Oxford Foot Model was used, simultaneously with a conventional lower limb model, to compare the kinematics of 10 forefoot varus children (aged 8-13) and 11 healthy controls (aged 7-13) during gait. Data acquisition was performed using a six-camera motion capture system, with a total of 27 reflective markers. A patient-by-patient comparison with the controls suggested several compensation patterns, although statistically significant differences were found only for the mean values of hip adduction/abduction during load response and midstance and hip flexion/extension during pre-swing. A multivariate statistical technique was used to determine which of the measured variables better separated both groups. The best discriminant model presented here includes hip adduction/abduction during load response, hindfoot/tibia inversion/eversion during pre-swing, hindfoot/tibia dorsiflexion/plantar flexion during load response and arch height during midstance, providing a rate of correct classification of 81%. The results could not fully confirm the kinematic relationships suggested in the literature. The small degree of forefoot varus deformity present in the patient group could have prevented other variables from becoming discriminant. A larger patient sample would help determine the possible different compensatory patterns to different degrees of forefoot varus.