PMC4075249_01
Preoperative X-ray of the affected foot. The MTP-1 joint is fused in malposition (yellow arrow). The X-ray shows the internal rotation of the proximal phalanx (white arrow), and the sesamoid bone is laterally shifted (blue arrow) (Hardy grade 4).
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However, the hallux pain did not disappear, and the painful callosities remained (Figures 1 and 2).
The affected foot. The laterally shifted tibial sesamoid and osseous rising of the proximal phalanx base have caused painful callosities (yellow arrows).
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However, the hallux pain did not disappear, and the painful callosities remained (Figures 1 and 2). It was found that there was a severely pronated position of the proximal phalanx against the metatarsal (approximately 70  pronated) (Figure 3), with subsequent lateral shifting of the tibial sesamoid and osseous rising of the proximal phalanx base that caused painful callosities (Figure 2).
Three-dimensional evaluation of the affected foot. The severely pronated position of the proximal phalanx against the metatarsal (approximately 70  pronated) is evident.
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It was found that there was a severely pronated position of the proximal phalanx against the metatarsal (approximately 70  pronated) (Figure 3), with subsequent lateral shifting of the tibial sesamoid and osseous rising of the proximal phalanx base that caused painful callosities (Figure 2). These K-wires were perpendicular to the longitudinal axis and horizontal plane of the metatarsal and proximal phalanx (Figures 3 and 4), and served intraoperatively as a rotational guide by parallelizing each other.
The simulation for setting the metatarsal and proximal phalanx cutting templates (red). The K-wires (green) are perpendicular to the longitudinal axis of the metatarsal and proximal phalanx. The projections given were programmed to guide the bone saw in cutting the metatarsal and phalanx perpendicular to the longitudinal axis (*).
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These K-wires were perpendicular to the longitudinal axis and horizontal plane of the metatarsal and proximal phalanx (Figures 3 and 4), and served intraoperatively as a rotational guide by parallelizing each other. The simulation for setting of the metatarsal and proximal phalanx cutting template is shown in Figure 4. The projections given were programmed to guide the bone saw in cutting the metatarsal and proximal phalanx perpendicular to the longitudinal axis (Figure 4).  
Intraoperative photograph of the custom-made surgical guide fixed with K-wires. (A, B) The distal end of the metatarsal and the proximal end of the proximal phalanx are fixed with K-wires with the aid of the 3D-CT-based custom-made surgical guide designed preoperatively. (C) The rotational position between the two bones is adjusted using the fixed K-wires as a rotational guide.
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Preparation of the osseous surfaces commenced with a flat resection of the distal end of the metatarsal and the proximal end of the proximal phalanx, which was carried out with the aid of the 3D-CT-based custom-made surgical guides designed preoperatively (Figure 5A and B) and fixed with the K-wires. The rotational position between the two bones was then adjusted using the fixed K-wires, which served as a rotational guide by parallelizing each other (Figure 5C).