Double-elevating osteotomy for late-presenting infantile Blount's disease: the importance of concomitant lateral epiphysiodesis.

We reviewed 34 knees in 24 children after a double-elevating osteotomy for late-presenting infantile Blount's disease. The mean age of patients was 9.1 years (7 to 13.5). All knees were in Langenskiöld stages IV to VI. The operative technique corrected the depression of the medial joint line by an elevating osteotomy, and the remaining tibial varus and internal torsion by an osteotomy just below the apophysis. In the more recent patients (19 knees), a proximal lateral tibial epiphysiodesis was performed at the same time. The mean pre-operative angle of depression of the medial tibial plateau of 49 degrees (40 degrees to 60 degrees ) was corrected to a mean of 26 degrees (20 degrees to 30 degrees ), which was maintained at follow-up. The femoral deformity was too small to warrant femoral osteotomy in any of our patients. The mean pre-operative mechanical varus of 30.6 degrees (14 degrees to 66 degrees ) was corrected to 0 degrees to 5 degrees of mechanical valgus in 29 knees. In five knees, there was an undercorrection of 2 degrees to 5 degrees of mechanical varus. At follow-up a further eight knees, in which lateral epiphysiodesis was delayed beyond five months, developed recurrent tibial varus associated with fusion of the medial proximal tibial physis.