A study of normal foot abduction across various age groups in children

Abstract

Introduction: The relapse rate after Ponseti method of correction has reduced in recent years which is attributable to the better appreciation of the need to achieve the correct degree of abduction. Ponseti recommended clinical 'overcorrection' of the foot to 70⁰ of abduction. However, no scientific basis for this figure was found in literature. As the indications of Ponseti method extend to older children, we conducted a study to find out the amount of foot abduction to be achieved before applying a foot abduction brace in various age groups.

Methods: The normal 197 feet of children up to eight years of age were considered for study. The measurements included foot-bimalleolar angle in neutral and maximum possible abduction, thigh foot angle and leg foot angle.

Results and discussion: The foot bimalleolar angle in neutral had a mean of 82.6 degrees and in maximum abduction a mean of 99.0 degrees. The mean leg foot angle was 66.4 degrees and the mean thigh foot angle was 60.5 degrees. It was found that these variables do not change with age. From the study we concluded that achieved abduction should be about 60-70 degrees before applying foot abduction brace in all children till age eight years with clubfeet treated with Ponseti technique, keeping the leg foot angle or the thigh foot angle as a guideline. This is against the common perception of keeping the abduction at 70 degrees for infants and reducing the abduction to 30 to 40 degrees for older children. Both the leg foot angle and thigh foot angles are reliable indicators of correction.

Keywords: Abduction at foot; Foot bimalleolar angle; Leg foot angle; Thigh foot angle.