A Comparison of an Advanced Metal Hip System to a Resurfacing Hip System

A standard hip replacement involves replacing your hip joint with several parts: the cup which forms the socket in the pelvis; a head that forms a new ball for the top of the thigh bone; and a stem which is placed into the thigh bone. Typically, the socket is made out of metal and plastic, and the ball and stem are made out of metal.

Recently, new metal-on-metal hip replacement systems have been developed where both the socket and the shell are made out of metal. This can cause metal ions to be released into the body. The CONSERVE® A-Class Total Hip with BFH technology is a new metal-on-metal total hip system which utilizes a large diameter femoral head (36-54 mm) more similar to the size of the original head (i.e., your original bone). Further, this system utilizes an advanced metal design which wears at a slower rate than typical metal-on-metal implants. Therefore, the primary purpose of the current study is to investigate if the CONSERVE® A-Class Total Hip with BFH technology will lead to lower blood ion levels in patients, as compared to patients in a recent study who received the CONSERVE® Plus Total Resurfacing Hip System, another metal-on-metal device. We are also comparing functional and radiographic (x-rays) outcomes between patients who receive the CONSERVE® A-Class Total Hip compared to those who have received the CONSERVE® Plus Total Resurfacing Hip System.

Inclusion criteria

• (1) Individuals undergoing unilateral total hip replacement with the CONSERVE® acetabular component and the CONSERVE® A-Class BFHä femoral head in combination with an uncemented femoral stem produced from the Ti-6A1-4V alloy (ASTM F-136) with or without titanium plasma coating.

(2) Patients who are undergoing primary hip surgery for Noninflammatory Degenerative Joint Disease (NIDJD). Composite diagnoses of NIDJD include osteo/degenerative arthritis, traumatic arthritis, congenital hip dysplasia, and avascular necrosis.

(3) Patients 18 years of age or older (skeletally mature). (4) Patients for whom there is a reasonable expectation that they will be available for each examination scheduled over a two year post-operative follow-up period and for annual exams until the last patient entered into the study has achieved two years of follow-up.

(5) Patients who agree to participate and sign the Informed Consent Form. (6) Patients who do not meet any of the exclusion criteria.

Exclusion criteria

• (1) Patients with previous fusions, acute femoral neck fractures, above knee amputations, or significant arthritic changes to the knees.

(2) Patients with evidence of active infection. (3) Patients with neurologic or musculoskeletal disease that may adversely affect gait or weight-bearing.

(4) Patients who have previously undergone an ipsilateral hemi resurfacing, total resurfacing, total bipolar, unipolar or total hip replacement device.

(5) Patients with neuropathic joints. (6) Patients with severe documented psychiatric disease. (7) Patients requiring structural bone grafts. (8) Patients with a documented allergy to cobalt chromium molybdenum. (9) Patients with an ipsilateral girdlestone. (10) Patients with sickle cell disease. (11) Patients with renal failure as defined by serum creatinine level greater than 180 Fmol/L.

(12) Patients who otherwise meet the study criteria, but refuse to consent in writing to participate in the study.