Treatment of genua valga in children by hemi-epiphysiodesis with a percutaneous transepiphyseal screw.

Background: Hemi-epiphysiodesis using percutaneous transphyseal screws is an established technique with good results to treat idiopathic genua valga in children. However, there is no evidence-based consensus on the optimal age for correction.

Purpose: This study aims to determine best age for optimal correction of the knee alignment.

Methods: All medical records of patients in our department treated by percutaneous hemiepiphysiodesis for idiopathic genua valga between 2007 and 2017 were reviewed. Skeletal age was determined pre-operatively. The hip-knee-ankle angle was measured on a standard frontal full leg radiograph, preoperatively, at time of removal of the screws and at skeletal maturity. The occurrence of correction loss and progression and the velocity of correction based on skeletal age were evaluated.

Results: A total of 164 legs were reviewed, of which 120 were followed until skeletal maturity. We perceived more insufficient valgus correction when treated at a skeletal age approximating skeletal maturity, however, also rebound valgus was noted in patients with only a short time to skeletal maturation at time of treatment. Overcorrection after screw removal was only perceived in 4.27%. A large individual variation in velocity of correction was observed.

Conclusion: In our study protocol with hemi-epiphysiodesis at 2 years from skeletal maturation, good results were obtained. Velocity of correction can be calculated to determine a patient specific timing for clinical and radiographical follow-up to avoid overcorrection.

Level of evidence: IV.