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

Completed

Conditions: Dysplasia; Hip

Interventions: Device: Hip stem

Registration Number: NCT04904640

Lead Sponsor: Istituto Ortopedico Rizzoli

Brief Summary: 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: 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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 150

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

Study & Design

Study Type: OBSERVATIONAL

Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
CLS stem	Hip stem	CLS Zimmer stem implantation (single wedge, tapered stem) using the 3D CT based software for surgical pre-operative planning
Wagner cone stem	Hip stem	Wagner cone Zimmer stem implantation (conical tapered stem) using the 3D CT based software for surgical pre-operative planning
Aptafix stem	Hip stem	Aptafix Ortho stem implantation (anatomical stem) using the 3D CT based software for surgical pre-operative planning

Primary Outcome Measures

Name	Time	Method
Correct Reconstruction Wagner Cone	Day 0	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
Correct Reconstruction CLS	Day 0	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
Correct Reconstruction Aptafix	Day 0	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

Secondary Outcome Measures

Name	Time	Method
Combined Anteversion CLS	Day 0	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
Combined Anteversion Aptafix	Day 0	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
Leg Lengthening Wagner Cone	Day 0	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
Offset CLS	Day 0	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
Combined Anteversion Wagner Cone	Day 0	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
Offset Aptafix	Day 0	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
Leg Lengthening CLS	Day 0	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
Offset Wagner Cone	Day 0	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
Leg Lengthening Aptafix	Day 0	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