Efficacy of the Ponseti Technique in Correcting Clubfoot Deformity and Influence of Residual Deformity in Patient Reported Outcomes: A Prospective Comparative and Controlled Study
Authors: Jasper Ryan , Morcuende Jose , Mallavarapu Vineel , Stebral Hannah J. , Carvalho Kepler A.M. , Mansur Nacime Salomao Barbachan , Talaski Grayson M. , Schmidt Eli , Dibbern Kevin , de Cesar Netto Cesar 
Published: December 2023

Category: Other; Hindfoot Introduction/Purpose: Clubfoot deformity (CFD) is one of the most common congenital deformities of the foot and ankle and is characterized by different severities of foot equinus, cavus, varus, and adduction. The gold-standard treatment is the Ponseti technique, characterized by serial casting and an Achilles tenotomy. Few studies have assessed long-term outcomes of this treatment, and none have utilized three-dimensional (3D) weightbearing analysis of residual CFD. The goals of this study were to elucidate residual 3D foot deformities in CFD patients treated with the Ponseti technique and to compare them with healthy controls. We also aimed to assess how these deformities influenced patient-reported outcomes (PROs). We hypothesized that significant residual deformities would be observed in CFD patients and that these deformities would negatively impact PROs. Methods: IRB-approved, prospective, comparative, and controlled study. We recruited 37 CFD patients (57 feet) treated with the Ponseti technique that had no additional foot and ankle surgical procedures. We also included 14 healthy control volunteers (28 feet) with no history of foot/ankle injuries/deformities. All patients underwent WBCT imaging (CurveBeam, HiRise). Tarsal bones were semi-automatically segmented (Bonelogic®, Disior), and several automatic measurements assessing cavus, varus, adductus, and overall 3D deformity (Foot and Ankle Offset – FAO) were performed. Measurements were then correlated with PROs, which included Visual Analogue Scale for pain, PROMIS general health, PROMIS physical function and pain interference, pain catastrophizing scale (PCS), and European Foot and Ankle Society (EFAS) score. Paired T-tests or Paired Wilcoxon were utilized to compare measurements between CFD patients and controls, depending on normality distribution. A multivariate regression analysis assessed the relationship between residual deformities and PROs in CFD patients. P-values < 0.05 were considered significant. Results: No significant overall residual 3D-deformity was found, with similar FAO measurements in CFD and controls (respectively, 2.63% and 3.2%/P=0.58). Slight cavus overcorrection was observed in CFD, with sagittal plane talus-first metatarsal angle of -0.12° versus -5.2o (p=0.04) and calcaneal inclination angle of 13.01° versus 21.5°, respectively. Varus under-correction was identified in CFD patients, with decreased sagittal and axial talocalcaneal angles (44.3o vs. 57.5o/p < 0.0001 and 17.7o vs. 25.78o/p=0.0012, respectively). Similarly, adductus under-correction was observed in CFD, with talonavicular coverage angle 18.63o vs. 29.19o (p < 0.0001). In the multivariate regression analysis, cavus overcorrection (sagittal talus-first metatarsal angle) was the only deformity influencing VAS (R2=0.19/P=0.02) and EFAS-Scores (R2=0.27/p=0.002). Residual varus deformity (sagittal plane talocalcaneal angle) was the only deformity influencing PROMIS Pain Interference (R2=0.14/p=0.038) and Physical Function (R2=0.32/p=0.0007). Conclusion: This study highlights the efficacy of the Ponseti technique in treating the overall 3D foot and ankle deformity in CFD patients, realigning the ankle joint and the weightbearing foot tripod. However, residual CFD components were identified, including overcorrection of the cavus and under-correction of the adductus and varus deformities. Overcorrection of the cavus negatively influenced VAS pain and EFAS scores, and under-correction of the varus negatively influenced PROMIS scores. The results of this study could potentially guide CFD treatment with the Ponseti technique, with focus on improved correction of the varus and avoidance of overcorrection of the cavus deformities.