Symax International Study

Study Overview
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Brief Summary
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The uncemented Symax hip stem is developed through optimization of the uncemented Omnifit hip stem. The Symax stem design combines an anatomical anteverted proximal geometry with a straight distal section. The proximal part is coated with a biomimetic hydroxyapatite (HA) coating for improved osseointegration to enhance load transfer and to minimize proximal bone loss. The distal part is treated with an anodization surface treatment in order to prevent distal bone apposition, which is expected to prevent distal loading and reduce proximal stress shielding. Aim of this study is to report mid-term clinical performance and evaluate whether the radiographic features are in line with the design principles of the Symax hip in an international clinical study with 5 years of follow-up.

Official Title
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5 Year Clinical and Radiographic Follow-up of the Uncemented Symax Hip Stem in an International Study

Conditions
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Hip Osteoarthritis, Prosthesis Durability

Intervention / Treatment
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* Device: Symax uncemented hip stem


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients requiring uncemented primary total hip arthroplasty (osteoarthritis, avascular necrosis and/or post-traumatic arthritis), age between 18-70 years, BMI less or equal to 35. Exclusion Criteria: Patients with bilateral hip complaints, impaired cognitive function and use of medication or illness influencing bone metabolism.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Symax uncemented hip stem<br>The Symax hip stem is an uncemented design forged from Ti6Al4V alloy (Stryker EMEA). Primary mechanical stability is provided by anatomical metaphyseal geometry. The hip stem features a size dependent anteversion, neck length and offset, with a CCD angle of 128°. Secondary biological stability is accomplished by fast osseous integration due to the BONIT-HA coating on the metaphyseal part of the stem. | Device: Symax uncemented hip stem<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of Harris Hip Score (HHS) during follow-up | A hip specific functional score | Preoperative HHS and postoperatively change in HHS at 6 months, 1 year, 2 years, 3 years and 5 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Radiographic evaluations | Radiographic evaluations per Gruen zone and comparison between two assessment teams | Immediately postoperative radiograhpic evaluation as baseline and changes in radiography at follow-up 6 months, 1 year, 2 years, 3 years and 5 years we evaluated the radiograhip evaluations again |