PMC5730420_01
Long-leg standing preoperative radiographs showing bilateral tibia vara at the age of 10 years (a) and progressive deformity at the age of 12 years (b). Corrective osteotomies of the proximal shaft of both tibias were performed with an external fixator at the age of 12 years (c).
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She was referred to our department at the age of 10 years for bilateral genu varum (Fig. 1a) along with a short neck, barrel chest, cubitus valgus, Madelung deformity, and short fourth metacarpal. Full-standing radiographs showed progressive tibia vara over a two-year follow-up period due to premature epiphyseal closure of the medial proximal tibia with bony bridging across the physes (Fig. 1b). She underwent acute valgus osteotomy of the proximal tibial shaft by using an external fixator at the age of 12 years (Fig. 1c).
Radiographs at the age of 15 years showing recurrence of the severe tibia vara in the right/left limb with 66 /69  of the medial proximal tibial angle and 194 /192  of the standing femorotibial angle.
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Bilateral genu varum recurred subsequent to the osteotomy of the proximal tibial shaft (Fig. 2).
The surgical procedures considered that the mechanical axis passed through the centers of the knees. In the closing-wedge high tibial osteotomy (HTO), the proximal tibial osteotomy level is set at 2 cm below the medial joint line and the lateral bone wedge was removed depending on the correction angle (a). In the opening-wedge HTO, the proximal tibial osteotomy level is set at 3.5 cm below the medial joint line, running obliquely upward to the tip of the fibular head (b). In the inverted V-shaped osteotomy, the apex of the "V" is proximal to the tibial tuberosity under the patellar ligament (c).
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Surgical options included, a closing-wedge HTO, opening-wedge HTO, and inverted V-shaped HTO (Fig. 3). On preoperative planning, closing-wedge HTO showed marked morphological change and decreased bone stock of the proximal tibia (Fig. 3a). Opening-wedge HTO demonstrated too large of an opening gap on the medial side to obtain sufficient correction angle (Fig. 3b). Compared with these other procedures, inverted V-shaped osteotomy would require a smaller amount of bone resection and opening gap (Fig. 3c).
Preoperative planning for the inverted V-shaped osteotomy demonstrates that right and left knees required correction angles of 23  and 32 , respectively. The resected segment of the triangular column-shaped lateral bone could be inserted into the medial opening site.
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The anterior and posterior cortices and periosteum at the apex of the V shape were preserved and used as a central hinge during correction by applying valgus stress (Fig. 4).
Postoperative radiographs showing complete valgus correction; the mechanical axis passes through the center of the knees; the MPTA is 87 /88  (a, b), and the standing FTA is 174 /172  in the right/left legs, respectively (c). Full-standing radiographs at the most recent follow-up showing retained bilaterally adequate configuration of the proximal tibia with residual right distal tibia varus and left mid-tibia valgus (d).
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Postoperative radiograph showed that mechanical axes pass through the centers of the knees, with 174 /172  of standing FTA and 86 /88  of MPTA in right/left legs (Fig. 5a-c). At more than 1.5 years after the inverted V-shaped osteotomies, she demonstrated bilaterally adequate configuration of the proximal tibia with residual right distal tibia varus and left mid-tibia valgus (Fig. 5d) and no functional limitations during daily activity.