Poor Evertor Muscle Activity Is a Predictor of Recurrence in Idiopathic Clubfoot Treated by the Ponseti Method: A Prospective Longitudinal Study With a 5-Year Follow-up.

BACKGROUND: After successful primary correction of the deformity in idiopathic clubfoot with the Ponseti method, recurrence has been reported to affect up to 40% of children. So far, it has been difficult to predict which feet are at risk of recurrence, despite numerous studies investigating various potential risk factors. The foot abduction brace (FAB) has been the standard of care in preventing recurrence but, even with excellent compliance, recurrences still occur. Increasingly, evidence points to a congenital neuromuscular imbalance constituting the deforming forces present in clubfoot. Poor evertor muscle activity has been cited specifically as a potential risk factor for recurrence. The aim of this study is to evaluate whether poor evertor muscle activity on clinical examination can predict recurrence in idiopathic clubfoot at 5-year follow-up.

METHODS: Data were collected prospectively on patients treated at our tertiary physiotherapy-led Ponseti service between 2010 and 2015. Hospital ethical approval was obtained. Sex, age, laterality, Pirani score, number of casts, brace compliance, and evertor activity were recorded. Evertor muscle activity was scored in a semiquantitative repeatable manner: 0, 0.5, or 1 as previously described. Recurrence was defined as deterioration of any of the 4 components of the deformity following a previously complete correction.

RESULTS: In total, 104 patients (172 feet) were included in the study, 76 patients had good evertor activity, and 28 demonstrated poor evertor activity. The mean follow up was 62 months (range, 41 to 71 mo); 18.3% of the patients (19/104) had recurrence treated with repeat casting; 13.5% (14/104) of the patients required additional surgery following recasting. Recurrence was highly associated with poor evertor activity (P<0.01).

CONCLUSIONS: Results at 5 years confirm that a semiquantitative evertor muscle activity assessment can predict recurrence and should be added to the routine clinical assessment in order to assist with individualizing patient's treatment strategies.

LEVEL OF EVIDENCE: Level II.