Article
MR-based 3D PAO planning and simulation of hip impingement is as accurate as CT-based 3D models
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Authors
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Till Lerch
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
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Celia Degonda
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
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Guoyan Zheng
- ISTB, Institute for Surgical Technologies and Biomechanis, Bern, Switzerland
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Inga Todorski
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
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Florian Schmaranzer
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
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Timo Ecker
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
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Klaus Siebenrock
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
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Moritz Tannast
- Inselspital, Universitätssklinik für Orthopädie, Bern, Switzerland
| Published: | October 23, 2017 |
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Outline
Text
Objectives: Femoroacetabular Impingement and hip dysplasia are complex three-dimensional deformities in young and active patients in the child-bearing age.
CT-based 3D Imaging can enhance diagnosis and allows planning and simulation of surgical corrections for these deformities. Planning of Periacetabular Osteotomy (PAO) for hip dysplasia or FAI due to acetabular retroversion can be performed with 3D Imaging. CT scan is the Gold standard for 3D Imaging but requires radiation doses up to 20mSv for the pelvis. We aimed to reconstruct 3D models based on radiation-free routine MRI of the hip joint.
we compared 3D models of the proximal femur and acetabulum reconstructed from CT and MRI data.
- 1.
- What is the mean surface distance between 3D models from CT and MRI data?
- 2.
- Do Range of motion values correlate for reconstructed 3D models
- 3.
- Do diagnostic parameters correlate for reconstructed 3D models from CT and MRI data
Methods: Comparative, prospective study involving 17 symptomatic patients (20 hips) with hip pain due to FAI or hip dysplasia.
CT scan and MRI of the entire pelvis and distal femoral condyles were obtained routinely for diagnostic preoperative evaluation. Standardized threshold-based manual segmentation was performed using commercial software (AMIRA). CT scans were obtained with 1mm and 2mm slice thickness, MRIs were obtained with 1mm slices for the hip joint and for the pelvis separately.
Both 3D models of the MRI and CT were used for 2 softwares to answer question (3) and (4). Manual segmentation was analyzed for the acetabulum and the proximal femur separately.
- 1.
- Mean and standard deviation of the surface distance between 3D models reconstructed from CT and MRI data were calculated. CT-based and MR-based Surfaces of the 3D models of the proximal femur and of the acetabulum were compared in AMIRA.
- 2.
- Specific software to assess range of motion and location of impingement of the native hip joint was used to assess Flexion, Extension, internal and external rotation in 90° of flexion, abduction and adduction.
- 3.
- Specific software for PAO planning was used to calculate Anteversion, Inclination, LCE angle, anterior, posterior and total coverage.
Results:
- 1.
- Mean surface distance was 0.76 mm +/- 0.13 for the proximal femur and 0.95 mm (SD +/-0.26) for the acetabulum. Median surface distance was 0.41mm (Maximum 0.59 mm) for the proximal femur and 0.47mm (Max. 1.08 mm) for the acetabulum.
- 2.
- Correlation for six range of motion values was excellent (r=0.993).
- 3.
- Correlation for 6 diagnostic parameters was excellent (r=0.97).
Conclusion: MR-based 3D models of the hip joint are as accurate as CT-based 3D models for proximal femur and acetabulum.
MR-based 3D models allow radiation-free preoperative detection of location of impingement, surgical planning and simulation of hip preserving surgeries. This can reduce the need for preoperative CT scans in young and active patients with hip pain due to FAI or hip dysplasia.
