Comparison of Hip Resurfacing and Cementless Metal-on-metal Total Hip Arthroplasty
Condition: Hip Osteoarthritis
MeSH terms: Osteoarthritis; Osteoarthritis, Hip
Study type: Interventional
Phase: Phase 4

Summary: 
      To compare clinical, functional and radiological outcome after hip resurfacing and cementless
      metal-on-metal total hip arthroplasty.
    

Detailed description: 
      While many problems associated with endoprosthetic surgery have been solved, there are still
      some open questions: In hip replacement one of the most controversial issues is the role and
      the indications for "resurfacing" (Schmalzried 2005, Hungerford 2005).

      Resurfacing In traditional hip replacement, the head of the femur is replaced with a metal
      head secured to a stem in the femoral canal. In hip resurfacing, the neck of the femur is not
      cut, and instead the head of the femur is capped with a hemispherical metal ball articulated
      with an acetabular cup. The concept of resurfacing was developed as early as the 1970s, but
      it was abandoned due to unsatisfactory results. The procedure started to spark new interest
      in the 1990s as the results improved due to improvements in the articulation surfaces and
      fixation techniques (Amstutz 1998), and it has become considerably more common in the 2000s.
      In Australia, for example, resurfacing procedures accounted for 9% of all hip replacement
      operations carried out as a consequence of primary osteoarthritis, and their use has
      increased 17-fold in the 2000s (Australian Orthopedic Association National Joint Replacement
      Registry).

      The partly assumed benefits of hip resurfacing include less bone resection in connection with
      the procedure, easiness of reoperation (a "conventional" replacement is carried out if
      reoperation is necessary), smaller risk of dislocation due to the larger head, and more
      physiological flexibility of the femur as the neck of the femur is not replaced with an
      inflexible metal stem. The short-term and mid-term results of modern resurfacing procedures
      presented in the reports of the developer clinics have been encouraging (Daniel 2004, Beaule
      2004), but long-term results are lacking. Resurfacing procedures are technically more
      challenging and have given rise to complications that are not associated with conventional
      hip replacement, such as fractures of the femoral neck (Shimmin 2005). On the other hand, the
      socket and the diameter of the ball used in resurfacing procedures and conventional hip
      replacements are similar, and excellent results have been reached with modern conventional
      cementless stems (Eskelinen 2005). There are no published studies comparing modern
      resurfacing prostheses to solutions involving cementless stems with a large head and
      metal-on-metal articulation surfaces.
    

Intervention name(s): Hip resurfacacing; Cementless total hip arthroplasty with m-o-m bearings
Intervention type(s): Procedure; Procedure
Intervention description(s): Hip resurfacing with cementless acetabular cup and cemented femoral head; Cementless monoblock acetabular cup and cementless femoral stem with modular large head and metal-on-metal bearings..
Other intervention name(s): BHR (Smith & Nephew, Memphis, TN, USA); BHR-cup and Synergy stem (Smith & Nephew. Memphis, TN, USA)
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Osteoarthritis; Hip; Artroplasty; Resurfacing