# Treatment of coronal knee angular deformities in children by a modified métaizeau percutaneous transphyseal screw technique

## TL;DR

This study evaluates a modified surgical technique for correcting knee deformities in children, showing it is safe, effective, and reduces operation time.

## Contribution

A modified Métaizeau percutaneous transphyseal screw technique is introduced, offering a simplified and efficient approach for treating knee deformities in children.

## Key findings

- The modified technique achieved significant radiological and clinical improvements with a 96% excellent functional outcome score at 24 months.
- Mean operative time was only 15 minutes, and no major complications were observed.
- The approach reduced fluoroscopy use and retained the benefits of the original PETS technique.

## Abstract

Knee coronal angular deformities are a frequently encountered challenge in paediatric orthopaedic practice. When surgical treatment is indicated, guided growth techniques have many advantages in managing these conditions. The purpose of this study is to evaluate the outcome of a modification of the original Percutaneous Epiphysiodesis using Transphyseal Screw (PETS) technique described by Métaizeau as a minimally invasive surgical approach in the treatment of knee angular deformities.

In this prospective study, a total of 14 patients (comprising 25 limbs) with a coronal plane deformity of the knee underwent percutaneous transphyseal screw hemiepiphysiodesis. Operative time is assessed. The patients were subsequently monitored for an average duration of 28 months.

The radiological assessment was conducted using the metrics of MAD (mechanical axis deviation), mLDFA (mechanical lateral distal femoral angle), and MPTA (medial proximal tibial angle). Clinical assessment included the intermalleolar distance (IMD) and intercondylar distance (ICD). The functional outcome evaluation was conducted using a modified version of the original Böstman score, taking into account the different age groups of the targeted cases.

In the genu valgum group, the mean preoperative values were: intermalleolar distance (IMD) 16.9 cm, mechanical axis deviation (MAD) 2.6 cm, and mechanical lateral distal femoral angle (mLDFA) 84°.

In the genu varum group, the mean preoperative values were: intercondylar distance (ICD) 8.4 cm, mechanical axis deviation (MAD) –3.0 cm, and medial proximal tibial angle (MPTA) 77.8°.

The mean operative time was 15 min. All radiological and clinical outcome measures showed significant improvement (P ≤ 0.05). At 24 months, 96% of cases achieved an excellent Böstman knee score. One patient reached skeletal maturity before full correction could be achieved. No other complications were observed.

This modification of the Métaizeau technique retains the advantages of PETS and offers a simplified approach that may reduce operative time and fluoroscopy use. Our results suggest that it is a safe and effective option for correcting coronal angular knee deformities in children. Further comparative studies are needed to confirm these potential benefits.