ABJHI Study Examines Hip Resurfacing as an Alternative to Total Hip Replacement
Alberta Bone and Joint Health Institute (ABJHI) is managing a long-term study comparing the safety and effectiveness of metal-on-metal (MOM) hip resurfacing with that of primary total hip replacement in young and middle-age adults who are active.
In MOM hip resurfacing, only the disease-damaged surfaces of the hip joint are removed. The surfaces are reshaped and capped with metal implants forming a metal-on-metal surface in the hip. The procedure conserves bone, and has been performed mainly in young and middle-age patients who are active and are expected to outlive conventional total hip replacement prosthesis.
In the conventional total hip replacement procedure, the entire thigh bone head and a portion of the neck are removed. Different implant types are available including a combination of metal and polyethylene and combinations of ceramic and metal.
Despite growing worldwide use, there is little reliable evidence on the risks and benefits of MOM resurfacing. The study being managed by ABJHI, called Alberta Hip Improvement Project (Alberta HIP), is examining rates of implant failure and the effects of metal particles released as the MOM implant surfaces wear from contact.
Alberta HIP is following male patients under the age of 66 and females under 56, reflecting the evidence-based consensus of experts that the procedure is most appropriate for young, active people with healthy bones. Although there is no age limit for conventional total hip replacement, Alberta HIP applied the MOM resurfacing age criterion to these patients to provide comparative results in a similar patient demographic. Alberta HIP began in 2004 and more than 1,200 patients are participating. They are being followed for 10 years after their surgery.
Click here to read the preliminary report, based on data from 2004 to 2009.
What the Research Team is Measuring and Reporting
- Rates of adverse events (deep vein blood clot, blockage of an artery in the lungs, heart attack, death)
- Rates of revision surgery (to repair, reposition or replace an implant)
- Rates of reoperation (at the same site but not involving the implant)
- Degree of return to normal function
- Reduction in pain
- Time in the operating room
- Duration of hospital stay
- Waiting time for surgery (from date of decision to have surgery to date of surgery)
Sub-study of Alberta HIP Examining Metal Particles in Blood
A sub-study of Alberta HIP is examining levels of metal particles, called ions, released into the blood as the metal surfaces in the hip resurfacing device wear. The levels and long-term health consequences of metal ions in the blood associated with metal-on-metal resurfacing are unknown. The ions consist of chromium and cobalt, the metal components in the implant.
A group of 174 MOM resurfacing patients in Alberta HIP consented to have blood tests for metal ion levels.