PMC5730418_01
Preoperative plain radiographs of the hip joint (A). The center-edge angle of the right hip was 65 . Postoperative plain radiographs of the hip joint (B). The center-edge angle was improved to 43 .
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Plain hip radiographs revealed a pincer deformity with center-edge angle (CEA) of 65 , which was larger than the reported upper limit of normal of 38  (Fig. 1A). CEA to 43  (Fig. 1B). Constructed 3D images using CT data revealed that the pincer lesion was resected as determined by preoperative simulation analyses (Fig. 4).
Simulation analyses detected which site of the acetabulum overlapped the femoral head-neck junction (yellow arrow) in frontal (A), backward (B), and upside views (C). We prepared the model of the acetabulum in which the impingement site was resected, and confirmed that there was adequate clearance between the acetabulum and the femoral head-neck junction in frontal (D), backward (E), and upside views (F).
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The anterosuperior to posterosuperior site of the overlapping acetabular rim overlapped the femoral head-neck junction, and preoperatively determined to be resected (Fig. 2A). Then, we prepared the 3D bone model of the pelvis in which the impingement site was resected, and confirmed that there was adequate clearance (Fig. 2B).
Kirschner wires were inserted in the acetabulum following the resection line determined by preoperative simulation analyses (A), and we confirmed that the wires were placed in the target line under radiographic guidance (B).
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Kirschner wires were inserted in the acetabulum following the resection line determined by preoperative simulation analyses (Fig. 3A), and we used intra-operative radiography to confirm that the wires were inserted in the appropriate site (Fig. 3B).
Three-dimensional reconstructed images of the acetabulum using computed tomography images. Preoperative images showed an ossified pincer lesion (yellow arrow) (A). The pincer lesion was resected as determined by preoperative simulation analyses (yellow arrow) (B).
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CEA to 43  (Fig. 1B). Constructed 3D images using CT data revealed that the pincer lesion was resected as determined by preoperative simulation analyses (Fig. 4).
Three-dimensional reconstructed images of the hip joint during squat using image-matching techniques. On the preoperative image, the pincer lesion (yellow arrow) was in close proximity to the femoral neck at maximum hip flexion (A). On postoperative images, the increased clearance between the femoral head-neck junction and acetabulum (yellow arrow) was demonstrated (B).
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Postoperative hip kinematics showed 63.3  of maximum hip flexion with 23.3  of pelvic posterior tilt, 92.6  of femoral flexion, 35.8  of hip abduction, and -14.4  of hip internal rotation (Table 1). 3D bone models at maximum hip flexion (Fig. 5) showed increased clearance between the femoral head-neck junction and the acetabular rim with a minimal rim-neck distance of 7.3 mm instead of 1.8 mm (Table 1).