A Study Investigating the Effect of Patient Pelvic Positioning and Method of Acetabular Component Insertion on Acetabular Component Inclination During Total Hip Arthroplasty (THA)

Study Overview
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Brief Summary
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Total Hip Arthroplasty (THA) is one of the most commonly performed orthopaedic operations worldwide. The main aim is overall improvement in levels of patient pain and mobility. Such surgery involves implantation of both an acetabular and femoral component. With the patient in the lateral decubitus position, the Orthopaedic Surgeon assumes that the pelvis is in a neutral position with respect to all three body planes at the time of acetabular component implantation. With regard to THA, the current orthopaedic literature demonstrates a clear relationship between acetabular component positioning, polyethylene wear and risk of dislocation. Problems with edge loading, stripe wear and squeaking are also associated with higher acetabular inclination angles, particularly in hard-on-hard bearing implants. The important parameters of acetabular component positioning are depth, height, version and inclination. Control of acetabular component inclination, particularly in the lateral decubitus position, is difficult and remains a challenge for the Orthopaedic Surgeon. Accurate implantation of the acetabular component within the 'safe zone' of radiological inclination is dependent on: Operative version Operative inclination Pelvic position (Primarily, but not exclusively, abduction / adduction.) This study aims to investigate the effect of patient pelvic positioning and method of acetabular component insertion on acetabular component inclination during Total Hip Arthroplasty (THA).

Official Title
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A Randomised Controlled Study Investigating the Effect of Patient Pelvic Positioning and Method of Acetabular Component Insertion on Acetabular Component Inclination During Total Hip Arthroplasty (THA).

Conditions
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THA, Total Hip Arthroplasty, Total Hip Replacement, THR

Intervention / Treatment
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* Procedure: Operating table position 0° head down (Horizontal)
* Procedure: Operating table position 7° head down.
* Procedure: Operating table position Y° head down
* Device: Standard straight acetabular component introducer without alignment guide.
* Device: Modified 35° acetabular component introducer.
* Device: Inclinometer-assisted acetabular component introducer.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients between the ages of 16 and 100 years awaiting primary Total Hip Arthroplasty the care of Professor D Beverland and Mr D Molloy in Musgrave Park Hospital will initially be invited to participate. Exclusion Criteria: Patients unable to provide fully informed consent.

Ages Eligible for Study
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Minimum Age: 16 Years
Maximum Age: 100 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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Design Details

Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 0° Head Down (horizontal) & Standard Introducer.<br>Operating table position 0° head down (horizontal) & standard straight acetabular component introducer without alignment guide. | Procedure: Operating table position 0° head down (Horizontal)<br> <br> Device: Standard straight acetabular component introducer without alignment guide.<br> <br> |
| Experimental: 0° Head Down (horizontal) & Modified 35° Introducer.<br>Operating table position 0°head down (horizontal) & modified 35° acetabular component introducer. | Procedure: Operating table position 0° head down (Horizontal)<br> <br> Device: Modified 35° acetabular component introducer.<br> <br> |
| Experimental: 0°Head Down (horizontal) & Inclinometer-assisted Introducer.<br>Operating table position 0°head down (horizontal) & standard straight acetabular component introducer without alignment guide. | Procedure: Operating table position 0° head down (Horizontal)<br> <br> Device: Inclinometer-assisted acetabular component introducer.<br> <br> |
| Experimental: 7° Head Down & Standard Introducer.<br>Operating table position 7° head down & standard straight acetabular component introducer without alignment guide. | Procedure: Operating table position 7° head down.<br> <br> Device: Standard straight acetabular component introducer without alignment guide.<br> <br> |
| Experimental: 7° Head Down & Modified 35° Introducer.<br>Operating table position 7° head down & modified 35° acetabular component introducer. | Procedure: Operating table position 7° head down.<br> <br> Device: Modified 35° acetabular component introducer.<br> <br> |
| Experimental: 7° Head Down & Inclinometer-assisted Introducer.<br>Operating table position 7° head down & inclinometer-assisted acetabular component introducer. | Procedure: Operating table position 7° head down.<br> <br> Device: Inclinometer-assisted acetabular component introducer.<br> <br> |
| Experimental: Y° Head Down & Standard Introducer.<br>Operating table position Y° head down (angle required to obtain vertical Transverse Pelvis Lines) & standard straight acetabular component introducer without alignment guide. | Procedure: Operating table position Y° head down<br>* Operating table position Y° head down (angle required to obtain vertical Transverse Pelvis Lines).<br>Device: Standard straight acetabular component introducer without alignment guide.<br> <br> |
| Experimental: Y° Head Down & Modified 35° Introducer.<br>Operating table position Y° head down (angle required to obtain vertical Transverse Pelvis Lines) & modified 35°acetabular component introducer. | Procedure: Operating table position Y° head down<br>* Operating table position Y° head down (angle required to obtain vertical Transverse Pelvis Lines).<br>Device: Modified 35° acetabular component introducer.<br> <br> |
| Experimental: Y° Head Down & Inclinometer-assisted Introducer.<br>Operating table position Y° head down (angle required to obtain vertical Transverse Pelvis Lines) & inclinometer-assisted acetabular component introducer. | Procedure: Operating table position Y° head down<br>* Operating table position Y° head down (angle required to obtain vertical Transverse Pelvis Lines).<br>Device: Inclinometer-assisted acetabular component introducer.<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Radiological acetabular component inclination. | The study has two primary aims, each with a different primary outcome. The first primary aim is to investigate the effect of adjusting patient pelvic position in the transverse plane by using a head down position of the operating table. This is to determine, when aiming for 35° of operative inclination, which operating table position most accurately achieves a target radiological inclination of 42° on the post-operative x-ray: 0° head down (Horizontal), 7° head down, or Y° head down (Angle required to obtain vertical Transverse Pelvic Lines). | Radiological acetabular component inclination will be measured on the routine post-operative pelvic x-ray, usually within 48 hrs from time of surgery. | 
| Operative Acetabular Component Inclination. | The study has two primary aims, each with a different primary outcome. The second primary aim is to determine which of the three methods of acetabular component insertion most accurately allows the Orthopaedic Surgeon to obtain the desired operative inclination of 35° during THA when using a cementless cup: Standard straight introducer without any alignment guide, Modified 35° introducer with horizontal alignment guide, or Digital inclinometer assisted introducer. | Operative acetabular component inclination will be measured intra-operatively. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of cases in which the target radiological inclination of 42 +/- 5° is actually obtained. |  | Radiological acetabular component inclination will be measured on the routine post-operative pelvic x-ray, usually within 48 hrs from time of surgery. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acetabular component inclination