Determinants of Surgical Response to Lateral Tibial Hemiepiphysiodesis in Idiopathic and Non-Idiopathic Genu Varum: Real-World Evidence from a Tertiary Pediatric Cohort

<b>Background</b>: Lateral tibial hemiepiphysiodesis with tension band plates is an established method for correcting genu varum in skeletally immature patients. However, outcomes may vary depending on underlying pathology and patient characteristics. <b>Methods</b>: This retrospective cohort study evaluated 31 patients (53 knees) treated between 2011 and 2024 at a tertiary pediatric orthopedic center. Patients were categorized as idiopathic or non-idioathic genu varum based on diagnosis. Inclusion criteria required open physes, absence of previous or concomitant knee surgeries for alignment correction, and availability of standardized long-standing radiographs. Radiographic parameters, including mechanical axis deviation (MAD), hip-knee-ankle angle (HKA), and medial proximal tibial angle (MPTA), were assessed pre-operatively and at implant removal. Outcomes were classified as complete correction, partial correction, absent correction, overcorrection, or progression of deformity. <b>Results</b>: Overall, 64.2% of knees achieved complete correction. Success was significantly higher in idiopathic cases (82.1%) than in non-idiopathic deformities (44%). Success was also more frequent in males (<i>p</i> = 0.040). In multivariable analysis, non-idiopathic patients (β = 351.9; <i>p</i> = 0.002), HKA improvement (β = 1.4; <i>p</i> = 0.010) and change in BMI z-score (β = 202.4; <i>p</i> = 0.009) independently predicted surgical success. No major complications (Clavien-Dindo-Sink grade > 2) were observed. <b>Conclusions</b>: Lateral tibial hemiepiphysiodesis is effective for idiopathic genu varum, offering minimally invasive correction with low complication rates. However, outcomes in non-idiopathic deformities are less predictable, emphasizing the need for individualized treatment planning and counseling. Early intervention, careful implant positioning, and rigorous follow-up are essential to optimize results and prevent unintended overcorrection.