To assess the therapeutic effect of hinged 8-figure plate by comparing with the traditional 8-figure plate through a randomized controlled clinical trial by assessing the differences between preoperative and postoperative data.

The hypothesis is that the hinged 8 plate provides low complications that this treatment is as good as the traditional one.

Angular deformities of the lower limb is major clinical problems encountered in pediatric orthopedics. Deformities can be either valgus or varus and most commonly affect the knee joint, which may result in patella dislocation, gait instability and serious impact on the appearance and function of the lower limbs. Biomechanical studies and gait analysis found that genu varus increased medial articular surface pressure of the knee, while genu valgus increased lateral articular surface pressure, and both of them are the risk factors for osteoarthritis. Surgical treatment techniques include osteotomy and hemiepipysidesis. Osteotomy surgery is the gold standard for severe angular deformity or epiphyseal closed patients, but it was associated with lots of complications, including osteofascial compartment syndrome, neurovascular injury, deep soft tissue infection, nonunion and requiring a long recovery time. While, for patients whose epiphyseal is not closed, the traditional 8 plate hemiepipysidesis has fewer complications. However, it showed some problems in clinical applications, such as steel plate or screw broken. The investigators designed a new hinged 8 plate, which has two arms and a built-in hinge. Based on the previous studies, investigators designed the rotation of the two arms ranged from 155° to 170° to better fit the contour of the physis in all stages of angular correction. That automatic change can also disperse repeated stress on the surface of periosteum and perichondrium during walking. The plate had been tested on animal models that the use of the hinged plate and screw system may be a more reliable technique with minimal complications for correction of angular deformities of the lower limb.

Inclusion Criteria:

1. Idiopathic genu valgus or varum
2. Without any treatment
3. lower limb mechanical axis over the tibial plateau in the range of 1/2;
4. Epiphyseal not yet closed, with more than 12 months of growth potential

Exclusion Criteria:

1. Physiological genu valgus or varum
2. Epiphyseal have closed or no growth potential
3. Pathological limb deformity(Blount disease, inflammation,trauma)
4. Other causes of lower limb angular deformity.
5. With surgical contraindications