Anterior Distal Tibia Hemi-Epiphysiodesis in Relapsed Ponseti Treated Clubfoot Patients: Beware of the Rebound Phenomenon

Background/Objectives: Anterior hemi-epiphysiodesis of the distal tibia (AHDT) with an 8-plate has been proposed as treatment for clubfoot patients with recurrent equinus deformity. However, to date, clinical results have been inconsistent and particularly focused on correction during treatment. In the current project, we specifically added evaluation of outcomes at least one year after 8-plate removal. Methods: We included Ponseti treated idiopathic clubfoot patients aged between 4 and 12 years who underwent AHDT between 2015 and 2022. Patients were assessed preoperatively at indication for 8-plate removal and if available at least one year after 8-plate removal. A senior orthopaedic surgeon specialized in clubfoot treatment determined passive ankle dorsiflexion. Furthermore, on standardized lateral radiographs, the anterior distal tibial angle (ADTA) was measured. Results: The median treatment duration of 46 feet (32 patients, 38% female) was 22.1 months (95–CI: 19.3–24.9). Both ankle dorsiflexion and ADTA improved significantly during AHDT. Of 35 feet, at least 1 year of follow-up after removal of hardware was available. The ADTA showed a significant increase (p < 0.001) after 8-plate removal, by modelling to preoperative values. The measured ankle dorsiflexion one year after 8-plate removal showed no change compared with the pre-treatment situation. One patient undergoing bilateral AHDT experienced a wound infection and screw migration. Conclusions: AHDT using an 8-plate is an effective method to achieve slope correction. However, after 8-plate removal, rebound of ADTA can occur. Physicians, parents, and patients should be informed about this mechanism, which might result in different timing of the treatment and possibly the need for renewed AHDT.