Comparison of Zimmer Maxera Acetabular System to the Allofit Cup with Roentgen Stereophotogrammetric Analysis (RSA) in Total Hip Arthroplasty

Rationale:

The Maxera Cup provides a large-head, ceramic-on-ceramic option for the younger and more active patient. The cup is an established hemispherical design. It is a cup system that offers high range of motion and a low-wear bearing to better enable the restoration of a patient¡¯s active lifestyle. The wear rates for Biolox delta material have been confirmed in vitro by hip simulator tests.

By mixing Zirconia and other oxide additives into the Alumina matrix, a composite is created that results in a significant reduction of the ceramic femoral head fracture rate. Nowadays the risk of poor performing survival over time should be limited to the max. The only clinical test that can provide data to predict long survival is stability testing with RSA. As a result, the risk of implanting potentially inferior prostheses in patients will be reduced, resulting in less suffering for patients and a reduction in healthcare expenses.

It is hypothesized that the clinical results, radiographic outcomes, implant survival, overall pain and functional performances of the Maxera Cup are equal to the Allofit Cup, up to ten years of follow-up.



Objective:

To perform a comparative assessment between the clinical and radiographic outcomes (as measured with RSA) of the Maxera Ceramic cup versus the standard uncemented polyethylene Allofit Cup all combined with the ML Taper stem in patients undergoing primary uncemented THA over a period of 10 years (primary objective is stability over 2 years). All complications will be documented.



Study design:

A prospective randomised clinical trial in which 50 cases (25 vs. 25) will be enrolled over one hospital. The primary components to be implanted are an uncemented ML Taper stem combined with the uncemented Maxera or Allofit cup cup. All patients will have a Ceramic head. Patients will be evaluated preoperatively and postoperatively at discharge (from operation date to date of discharge), at 6 weeks, 3 months, 6 months,1 year, 2 years, 5 years, 7 years and 10 years. The 7 years follow up will be without RSA.



Study population:

The study population consists of active male or non-pregnant female 18-75 years of age, with a QI <35. The subjects have no clinical relevant disorders of the hip and they undergo a primary total hip replacement by dr. Bloem, after diagnosis of osteoarthritis or avascular necrosis.



Intervention (if applicable):

Placement of an uncemented Maxera® or Allofit® cup in combination with an uncemented ML Taper stem®.



Main study parameters/endpoints:

Outcome will be clinically measured using the Harris Hip Score (HHS), Oxford Hip score (OHS) and EQ5-D, whilst radiographic outcomes will be evaluated through standard radiographic parameters which include qualitative femoral and acetabular findings as well as position of the stem and cup. RSA will be used to measure cup migration.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

Subjects participating in the study have the same risks and benefits when not participating in the study. All components used in the study have CE mark and are already in use. Follow-up times are standard protocol evaluations of prosthesis in our clinic. Besides standard radiological follow-up, RSA x-rays will be made to measure the fixation of the cup.

The clinical results, radiographic outcomes, implant survival, overall pain and functional performances of the Maxera Cup are equal to the Allofit Cup, up to ten years of follow-up.

- Preoperative

- Postoperative before discharge

- 6 weeks postoperative

- 3 months postoperative

- 6 months postoperative

- 1 year postoperative

- 2 years postoperative

- 5 years postoperative

- 10 years postoperative

Placement of an uncemented Maxera or Allofit cup in combination with an uncemented ML Taper stem.