What exactly is "foot abduction" during management of idiopathic clubfoot in clinical practice?

PURPOSE: There is however gross ambiguity regarding the use of term "foot abduction" in clubfoot treatment. We measured below defined angles at different stages of clubfoot treatment to decipher their precise interpretation.

METHODS

In a prospective evaluation of 25 unilateral clubfeet in infants' age less than six months treated with Ponseti technique, clinical leg foot and thigh foot angle were measured at talar head reduction (LHT0), pre-tenotomy, and post-tenotomy stage. A "normal" reference was available in the form of measurements of contralateral limb.

RESULTS

Talar head (LHT0) was reduced at mean leg foot angle of 26 degrees. The corresponding pre- and post-tenotomy angles were 42.6 and 50.0 degrees, respectively. The reference leg foot angles for contralateral limb were 49.8 degrees. The thigh foot angle for LHT0, pre-tenotomy, post-tenotomy, and contralateral side were, respectively, 39.2, 56, 68, and 65.6 degrees. There was an additional tibial external rotation component of mean 13.4 degrees (SD 4.5) in the thigh foot angle when compared to the leg foot angle at tenotomy. This increased to 18 degrees (SD 3.4) post-tenotomy.

CONCLUSIONS

The study suggested that the foot abduction described in the "Ponseti Manual" probably intends thigh foot rather than leg foot angles. There was a significant difference in the angles when talar head reduced and tenotomy was decided. The foot abduction is an ambiguous term which should be replaced by the more specific leg or thigh foot abduction angle.