Investigating Proximal Migration in Trabecular Metal Cups Used In Acetabular Revision Surgery

Study Overview
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Brief Summary
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This study is intended to compare the proximal migration of the tantalum design (TM) with a cemented cup used in conjunction with bone allografting in cases with major bone loss. A group of patients with good periacetabular bone stock are included to analyse the differences between the tantalum and titanium design regarding risk of loosening and differences in clinical outcome measures. Radiostereometry (RSA) is used to accurately measure migration and rotation of the revision cups.

Detailed Description
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Acetabular component loosening is often associated with periacetabular bone loss. Different approaches are described to address the bone defects in acetabular revision surgery. Several authors have reported inferior results when uncemented Titanium alloys and older porous coated designs are used in acetabular revisions with significant bone loss. Cemented fixation of the revision cup with impaction bone grafting (BIG), introduced more than three decades ago has today a thorough documentation. The Tantalum designs, with inherent properties such as high volumetric porosity, low modulus of elasticity and high friction against the bone, have been suggested to improve the fixation of the acetabular component. Several authors have been reporting promising short- and medium-term results using the TM designs in acetabular revisions with large periacetabular bone defects. Proximal migration measured with radiostereometry (RSA) has been suggested to predict risk for late aseptic loosening in hip prosthesis surgery. This study was primarily to compare the proximal migration of the tantalum design with a cemented cup used in conjunction with bone allografting in cases with major bone loss. A group of patients with good periacetabular bone stock are included to analyse the differences between the tantalum and titanium design. RSA is used to accurately measure migration and rotation of the revision cups.

Official Title
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Is the Trabecular Metal Cup Associated With Lower Risk of Aseptic Loosening in Acetabular Revision Surgery?

Conditions
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Prosthesis Loosening

Intervention / Treatment
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* Device: Trilogy cup
* Device: Trabecular metal cup (TM)
* Device: ZCA cup


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients with a loose acetabular component, undergoing revision Exclusion Criteria: Patient not able to understand the intention of the study

Ages Eligible for Study
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Maximum Age: 85 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

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Small periacetabular bone defects<br>Patients with cup loosening and small periacetabular bone defects | Device: Trilogy cup<br> <br> Device: Trabecular metal cup (TM)<br> <br> |
| Experimental: Large periacetabular bone defects<br>Patients with cup loosening and large periacetabular bone defects | Device: Trabecular metal cup (TM)<br> <br> Device: ZCA cup<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proximal migration measured with RSA | All patients have been recruited (operated on) by end of December 2011. Our primary intention is to follow all patients a minimum of two years with RSA. | 24 month postoperatively. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patient reported outcome measures | Harris Hip Score | first two years postoperatively |