# Radiographic Impact on the Clinical Decision Making of Achilles Tenotomy in Clubfoot: In Search of an Objective Cut-Off Value

## TL;DR

This study identifies a radiographic cut-off value to help decide when to perform Achilles tenotomy in clubfoot patients.

## Contribution

The study provides an objective radiographic cut-off value of >85° for lateral tibio-calcaneal angle to guide Achilles tenotomy in clubfoot.

## Key findings

- A cut-off value of >85° for the lateral tibio-calcaneal angle showed high sensitivity and specificity for indicating Achilles tenotomy.
- Patients with angles above 85° showed significant improvement after tenotomy.
- The accuracy rate of the cut-off value was 94.4% with an AUC of 0.983.

## Abstract

Background: We tried to determine whether the indication of Achilles tenotomy (AT) in clubfoot patients based on clinical evaluation could be confirmed radiographically, and to find an objective radiographic cut-off value for its indication. Methods: Eighty-six clubfeet from 60 patients, (26 bilateral and 34 unilateral) were included. A standard Ponseti treatment regimen was applied. Group 1 comprised patients who underwent AT immediately after serial plaster casting (26 feet). Group 2 comprised patients who underwent AT during the follow-up period (48 feet). Group 3 comprised patients who were assumed to have a corrected foot and did not undergo AT (12 feet). Group 4 comprised the healthy sides of the unilateral cases (34 feet). Results: Both Group 1 and Group 2 showed significant improvement after tenotomy (p = 0.002). In order to differentiate between the normal and AT groups according to the pre-tenotomy angle, we obtained an optimal cut-off value of >85° according to the Youden index, a sensitivity of 96%, a specificity of 91.2%, a positive predictive value of 95.9%, a negative predictive value of 91.2%, and an accuracy rate of 94.4% (AUC: 0.983; p < 0.001). Conclusions: Feet with a lateral tibio-calcaneal angle > 85° can be considered pathologic and accepted as candidates for AT.