BACKGROUND: The hemiepiphyseal stapling has both positive and negative effects on effective leg length. The purpose of this study was to analyze change in effective leg length after angular correction by hemiepiphyseal stapling, and to validate in clinical cases. METHODS: Mathematical analysis of a hemiepiphyseal stapling model was conducted. The induced formula was validated in 6 cases fulfilling the assumptions of the model. Anatomical parameters involved in this formula were measured in additional 21 cases undergoing hemiepiphyseal stapling or hemiepiphysiodesis. RESULTS: Effective leg length increased or decreased according to three parameters in this model: 1) limb length distal to the operated physis (L), 2) width of the operated physis (d), and 3) the amount of angular deformity to be corrected (theta). Actual change in effective leg length of 6 cases similar to this model coincided with the predicted change at least in its direction. L/d ratio was 4.82 +/- 0.51. CONCLUSIONS: Considering the narrow range of the L/d ratio, hemiepiphyseal stapling is likely to decrease effective leg length if the amount of angular correction is less than 10degrees, whereas to increase it if the amount of angular correction is larger than 16degrees. This should be taken into consideration when selecting the surgical method for angular deformity correction in skeletally immature patients.
Adolescent ; Child ; Epiphyses/growth & development/*surgery ; Female ; Genu Valgum/*surgery ; Genu Varum/*surgery ; Humans ; Leg Length Inequality/diagnosis/*etiology ; Male ; *Surgical Stapling/adverse effects

BACKGROUND: Percutaneous lateral hemiepiphysiodesis of the lower extremity is a simple and excellent method to correct the angular and length problems cosmetically. However, the efficacy of percutaneous lateral hemiepiphysiodesis is not well established in the literature. The purpose of this study was to evaluate the efficacy of percutaneous lateral hemiepiphysiodesis for angular corrections in adolescent idiopathic genu varum patients with proximal tibia vara and identify the factors affecting the amount of deformity correction of the lower limb in the coronal plane. METHODS: We retrospectively reviewed 20 patients (40 lower limbs) who had percutaneous lateral hemiepiphysiodesis on the proximal lateral tibia between 1997 and 2010. Radiographic evaluations were made using (1) the hip-knee-ankle angle and (2) the length of the tibia. Furthermore, the intercondylar distance was evaluated at the level of the knee joint. Preoperative factors (gender, age, body mass index, intercondylar distance, preoperative hip-knee-ankle angle, remaining growth of tibia, and calculated correctable angle) were analyzed, as well as their correlation with the degree of the actual correction angle. RESULTS: The amount of coronal deformity of the lower limb was improved from its preoperative state. The median average of hip-knee-ankle angle improved from 8.0degrees (interquartile range [IQR], 7.0degrees to 10.0degrees) preoperatively to 3.0degrees (IQR, 2.5degrees to 4.0degrees) at the final follow-up (p < 0.001). The median percent ratio of the angular correction was 60% (IQR, 50% to 71.3%). The correlation coefficients were -0.537, 0.832, 0.791, and 0.685 for the bone age, preoperative hip-knee-ankle angle, the remaining growth of tibia, and calculated correctable angle, respectively. CONCLUSIONS: Despite the excellent cosmetic outcome of percutaneous lateral hemiepiphysiodesis on the proximal lateral tibia in adolescent idiopathic genu varum, the effect was limited in most cases. For optimum results, surgery a few months earlier is recommended, rather than at the calculated operation time.
Adolescent ; Child ; Female ; Genu Varum/diagnostic imaging/pathology/*surgery ; Humans ; Leg Bones/diagnostic imaging/pathology/surgery ; Male ; Orthopedic Procedures/*methods ; Retrospective Studies ; Tibia/diagnostic imaging/pathology/*surgery ; Treatment Outcome