ANFH after a femoral neck fracture in children and adolescents is associated with limb shortening and deformity of the proximal femur, i.e., shortening of the femoral neck, overgrowth of the greater trochanter resulting in post-traumatic varus, reduced articular-trochanteric distance and limb shortening. VITO allows both a reorientation of the necrotic segment and, at the same time, a change of the shape of the proximal femur, with lengthening of the shortened limb. Various techniques of valgus intertrochanteric osteotomy have been described in the literature [17, 22, 23]. We prefer the classical technique with the use of a 120-degree angled blade-plate, which allows a lateral shift of the femoral shaft and, if need be, flexion/extension of proximal fragment [14, 16, 24, 25].
Of great importance for indication of intertrochanteric osteotomy (ITO) in partial ANFH are preoperative MRI scans, which serve for an exact determination of the size of the necrotic segment and its localization. These details are essential for the choice of the osteotomy type (varus/valgus), the wedge size, or the valgus angle. Based on localization of the necrotic segment in sagittal MRI scans, valgus (varus) osteotomy may be combined with flexion/extension osteotomy in the sagittal plane. This was the case of patient N1, where VITO was combined with a 15-degree flexion osteotomy.
Multiple studies in the literature deal with the results of intertrochanteric osteotomy for ANFH, however, only a few of them focus on ANFH after femoral neck fractures in children and adolescents [14, 15, 18–20].
Boitzy, Forlin et al. and Nötzli et al. [15, 18, 19] described results of 11, 16 and 3 patients respectively with an average follow up 2–7 years. Patient age at the time of injury was 8–20 years. The reported results are different.
In 2008 Abbas et al. [20] described three patients after rotational transtrochanteric osteotomy. Patient age at the time of injury was 12–15 years and good results were achieved in all three cases.
The problem of all these studies, including our initial one, was a small number of patients and a short follow-up period, not exceeding seven years [14, 15, 18–20]. In our present study, the minimal follow-up is 15 years, which has no parallel in the literature. In all 5 patients, VITO considerably improved the function of the hip joint; only in one female patient (N5) did the condition deteriorate over 15 years postoperatively.
A disadvantage of this study is a small number of patients, which does not allow a detailed analysis of the factors influencing the VITO result; nevertheless, the best results seem to be associated with younger patients with a preserved growth potential. In these patients with open physes of the contralateral proximal femur, however, it is necessary to take into account a potential relative shortening after lengthening of the affected limb.