Biomechanical Reconstruction of Three Different Hip Stem Designs in Hip Dysplasia Using a 3D CT-based Planning Software

Study Overview
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Brief Summary
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A random population of 200 CT scans of pelvis and thigh in an adult population affected by hip dysplasia will be selected. The aim of this study is to evaluate the biomechanical reconstruction of the hip anatomy provided by three different hip stem designs in dysplastic cases, using a 3D CT based software for pre-operative planning.

Detailed Description
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Pre-operative planning in hip arthroplasty with dedicated software is a useful guide to provide a better reconstruction of the biomechanical parameters of the replaced hip and to optimize the choice of component, improving the geometric understanding of the hip anatomy and the interaction between the native morphological structure and the prosthetic component. The use of a 3D CT-based software for pre-operative planning may provide a better knowledge of the hip anatomy, simulating the biomechanical parameters more closely than a 2D X-ray-based software. In addition, it is the only way to anticipate the correct interaction between the prosthetic components, or the combined anteversion, a key factor in preventing implant instability. Severe hip deformities, like developmental hip dysplasia, may not be adequately reconstructed by every implant and 3D pre-operative CT may increase the three-dimensional anatomical knowledge of the hip, improving the choice of the correct implant and possibly reducing the possible consequences of intra and post-operative complications. Therefore, the purpose of this study is to pre-operatively plan, in a random series of 200 native pelvis and thigh CT scans performed in patients with hip dysplasia, 3 different types of hip stem designs using the 3D Hip-Op software, with the aim of analyzing, on the CT simulations, the percentage of adequate reconstruction of the optimal biomechanical parameters (combined anteversion between 25°-50°, global offset not inferior to 12% of the native offset, leg lengthening not superior to 3 cm, sagittal and coronal tilt not superior to +/-5°, canal filling not inferior to 80%). The percentage of every stem design providing the optimal reconstruction in dysplastic hips (all the 5 parameters matched) will be assessed. The single parameters, especially the combined anteversion, the offset restoration and the leg lengthening, will be assessed for every simulation.

Official Title
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Evaluation of the Reconstruction of Biomechanical Parameters Provided by Three Different Hip Stem Designs in Developmental Hip Dysplasia Using a 3D CT-based Software for Surgical Planning

Conditions
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Dysplasia; Hip

Intervention / Treatment
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* Device: Hip stem


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: definition of developmental hip dysplasia according to Wiberg (center edge angle <20°) pre-operative CT scan extended from the fourth lumbar vertebra to the tibial plateaus Exclusion Criteria: other types of hip pathologies inadequate Ct scans

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| CLS stem<br>CLS Zimmer stem implantation (single wedge, tapered stem) using the 3D CT based software for surgical pre-operative planning | Device: Hip stem<br>* In every hip (with appropriate CT scan), 3 different stem designs will be positioned using a 3D Ct based software for surgical pre-operative planning.<br>|
| Wagner cone stem<br>Wagner cone Zimmer stem implantation (conical tapered stem) using the 3D CT based software for surgical pre-operative planning | Device: Hip stem<br>* In every hip (with appropriate CT scan), 3 different stem designs will be positioned using a 3D Ct based software for surgical pre-operative planning.<br>|
| Aptafix stem<br>Aptafix Ortho stem implantation (anatomical stem) using the 3D CT based software for surgical pre-operative planning | Device: Hip stem<br>* In every hip (with appropriate CT scan), 3 different stem designs will be positioned using a 3D Ct based software for surgical pre-operative planning.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correct Reconstruction CLS | Percentage of hips correctly reconstructed using CLS stem: the correctly reconstructed hip should have combined anteversion between 25° and 50°, global offset not inferior to 12% of the native offset, leg lengthening not superior to 3 cm, sagittal and coronal tilt not superior to +/-5°, canal filling not inferior to 80% (all the 5 parameters should be present at the same time). Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 the worst | Day 0 | 
| Correct Reconstruction Wagner Cone | Percentage of hips correctly reconstructed using CLS stem: the correctly reconstructed hip should have combined anteversion between 25° and 50°, global offset not inferior to 12% of the native offset, leg lengthening not superior to 3 cm, sagittal and coronal tilt not superior to +/-5°, canal filling not inferior to 80% (all the 5 parameters should be present at the same time). Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 the worst | Day 0 | 
| Correct Reconstruction Aptafix | Percentage of hips correctly reconstructed using CLS stem: the correctly reconstructed hip should have combined anteversion between 25° and 50°, global offset not inferior to 12% of the native offset, leg lengthening not superior to 3 cm, sagittal and coronal tilt not superior to +/-5°, canal filling not inferior to 80% (all the 5 parameters should be present at the same time). Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 the worst | Day 0 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Combined Anteversion CLS | Percentage of hips with adequate combined anteversion according to Dorr (25-50°) and Widmer (<37°) using CLS stems. Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Combined Anteversion Wagner Cone | Percentage of hips with adequate combined anteversion according to Dorr (25-50°) and Widmer (<37°) using CLS stems. Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Combined Anteversion Aptafix | Percentage of hips with adequate combined anteversion according to Dorr (25-50°) and Widmer (<37°) using CLS stems. Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Offset CLS | Percentage of hips with acetabular+femoral offset not inferior to 12% of the native value using CLS stems. Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Offset Wagner Cone | Percentage of hips with acetabular+femoral offset not inferior to 12% of the native value using CLS stems. Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Offset Aptafix | Percentage of hips with acetabular+femoral offset not inferior to 12% of the native value using CLS stems. Minimum-maximum values (as percentage %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Leg Lengthening CLS | Percentage of hips with leg lengthening not superior to 3 cm using CLS stems. Minimum-maximum values (as percentages %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Leg Lengthening Wagner Cone | Percentage of hips with leg lengthening not superior to 3 cm using CLS stems. Minimum-maximum values (as percentages %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 
| Leg Lengthening Aptafix | Percentage of hips with leg lengthening not superior to 3 cm using CLS stems. Minimum-maximum values (as percentages %): 0-100. 100 is the best result, 0 is the worst | Day 0 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Hip arthroplasty, Hip stem, Pre-operative planning, Combined anteversion, Offset, Developmental dysplasia of the hip