A Multicentre Trial to Compare Two Articulating Bearing Surfaces as Used in Cementless Primary Hip Arthroplasty

A Multicentre Prospective Randomised Control Trial to Compare Two Articulating Bearing Surfaces, Ceramic on Metal and Metal on Metal Large Diameter Femoral Heads, as Used in Cementless Primary Hip Arthroplasty

The aim of this study is to demonstrate the non-inferiority of the ceramic-on-metal articulation using large diameter bearings (38mm to 60mm) compared to the metal on metal articulation using the same cup in regards to the composite clinical success (CCS) rate at 2 years postoperatively (delta = 10% minimum clinically significant difference in rates).

This multicentre randomised controlled trial will compare the clinical outcome of the ceramic-on-metal articulation against a metal-on-metal articulation using the same Recap Acetabular cup.

The metal ion release will be evaluated at predetermined postoperative intervals during the first 36 months. A trial will be conducted as a clinical trial in accordance with the Medical Devices Directive 93/42/EEC (2002).

A total of 150 patients have to be recruited from the South African centre (2 groups)

The initial study assessment period will be 48 months; 24 months recruitment and 24 months follow-up. The follow-up reviews will be at 6 weeks, 6 months, 1 year, 2 years and 3 years. A 5 year and 10 year clinical review will also be carried out with all patients.

An assessment of incidences of adverse events and metal ion release concentrations will be made when all patients are at 6 months postoperatively.

Inclusion Criteria:

• Primary total hip replacement
• Patient with degenerative joint disease (inflammatory or non-inflammatory) or any of the composite diagnoses of osteoarthritis,avascular necrosis, legg perthes, rheumatoid arthritis, diastrophic variant, fracture of the pelvis, fused hip, slipped capital epiphysis, subcapital fractures, traumatic arthritis
• Patients preoperative Harris hip score < 80 points
• Patients with limited co-morbidity - ASA I - III
• Patients with normal urea and electrolyte levels and creatinine levels
• Patients must be able to understand instructions and be willing to return for follow-up
• Patients willing to provide blood and urine samples for metal ion analysis at follow-up

Exclusion Criteria:

• Patient preoperative Harris hip score > 80 points
• Pre-existing metal implants
• Patients with significant co-morbidity - ASSA IV - V
• Dementia and inability to understand and follow instructions
• Neurological conditions affecting movement
• Women younger than 45 years old
• Presence of symptomatic arthritis in other lower limb joints
• Patients requiring smaller than 38mm and larger than 60mm diameter femoral heads
• Patients taking NSAIDs and / all drugs that will affect bone metabolism