SURGICAL DECISION IN THE PONSETI METHOD: ROLE OF ULTRASOUND

Abstract

A less invasive surgical treatment of clubfoot is increasingly considered, it aims to limit extensive exposure, to improve the functional and cosmetic outcome and to lower the risk of stiffness and recurrence of the deformity. The Ponseti method consists in an original casting technique followed, only in the most resistant clubfeet, by a percutaneous Achilles tenotomy. Critical decision is the selection of the clubfeet which needs tenotomy. Purpose of this study was to determine if ultrasound assessment of clubfoot may be helpful in making surgical decision.

MATERIAL AND Methods: 98 newborns with 122 congenital clubfeet were treated by the Ponseti casting technique from mid-2000 to June 2006. According to Manes classification, there were 20 mild, 47 moderate and 55 severe clubfeet. After 3 to 8 weeks of casting, clubfeet candidate to surgery underwent sonographic assessment according to the original technique previously published by the authors. On the sagittal posterior plane the R.O.M. of the ankle and subtalar joints was stated both in neutral position and under manipulation. No surgery was performed in clubfeet with normal sonographic dorsiflexion, percutaneous tenotomy was done in clubfeet with mild limited sonographic dorsiflexion and more extensive posterior release (tendon Z-lengthening and posterior cut of ankle and subtalar joint) was performed in clubfeet with most evident sonographic persistent equinus and anterior dislodgment of the talus in the ankle mortise. The R.O.M. was checked again by ultrasound at the end of treatment. According to Ponseti method a Denis Browne bar, with clubfoot 60° externally rotated, was worn full time until the walking age.

Results: 35/122 clubfeet (28,6%) were treated conservatively (all the 20 mild and 15/47 of moderate deformities), 87/122 (71,4%) surgically (32/47 of moderate deformities and all the 55 severe deformities). On the basis of the dynamic ultrasound evaluation 38 clubfeet underwent simple tenotomy and 49 ones underwent extensive posterior release. At the end of the casting normal dorsiflexion was documented by ultrasound in 72 (82,7%) of the operated feet.

Conclusions: The need of surgery in the Ponseti casting technique shows a great variability in Literature. These controversial data are probably due not only to the different confidence in the Ponseti method, but also to the different criteria used in evaluating the correction obtained by casting. Ultrasound assessment of the deformity gives objective qualitative and quantitative information about the restoration of the physiological dorsiflexion and articular biomechanics. On the basis of this simple, non invasive and widely available procedure the surgeon can evaluate the effectiveness of the serial casting and may be able to establish and graduate the need of corrective surgery.