Adolescent Blount disease in obese children treated by eight-plate hemiepiphysiodesis

The aim of this study is to evaluate the outcomes of eight-plate (Orthofix) use during hemiepiphyseodesis operation for growth modulation in obese children with adolescent Blount disease.

Six limbs of five consecutive patients who underwent lateral proximal tibial eight-plate (Orthofix) hemiepiphysiodesis were evaluated. The body mass index (BMI) was >30 and the severity of the deformity was in Zone III according to the Mielke and Stevens definition. The mechanical medial proximal tibial angle (MPTA) and the mechanical axis deviation (MAD) were measured preoperatively, postoperatively, and at last follow-up. The outcome of the procedure was established by the degree of tibia vara correction degree at final plate removal or skeletal maturity.

Mean age of the patients and mean BMI at the time of surgery was 13 years (range 12 to 14) and 33.5 kg/m2 (range 31 to 36), respectively. Patients were followed for an average of 22 months (range 13 to 31). Preoperative and last follow-up mean values for MPTA were 81 and 80 degrees, respectively. Outcome of the procedure showed two extremities demonstrated progression of the tibia vara (mean of 6.5 degrees), two extremities had no correction of the deformity, and the remaining two extremities showed minimally improvement (mean 3 degrees). The procedure failed to correct the tibia vara in all extremities and all patients were scheduled for an osteotomy to treat the deformity.

We do not recommend the use of a tension band plate hemiepiphyseodesis (eight-plate, Orthofix) to treat severe adolescent Blount disease in obese children.