Why Uncemented Implants?
Uncemented fixation on the femoral side gives superior results to cement. Cement is a brittle acrylic material that heats up during implantation (polymerization reaction) burning the femoral head and increasing the chance of early femoral failure. It also is subject to fatigue failure over time resulting in implant loosening type failure. With uncemented femoral components we have had a 100% bone ingrowth rate. We have had only one early femoral failure (fracture or head collapse) in the last 2000 uncemented resurfacings. We have had no loosenings. The benchmark rate for these failure mechanisms in cemented femoral components is 1-2% for early failure and 3% for loosening.
Why Minimally Invasive Surgery?
When hip resurfacing is performed through a minimally invasive 4-5 inch posterior approach the hospital stay is minimized and the recovery is rapid. Transfusion is almost never required. Pain control is excellent. This is more complex for the surgeon. But we have published results that indicate no increase in complications and a better early outcome using this technique.
Accurate X-ray Based Component Positioning
The most critical factor in consistently achieving excellent outcomes in resurfacing is accurate acetabular component positioning. Adverse (Metal) Wear Related Failures (AWRF) can now be completely avoided, even in higher-risk patients requiring smaller implant sizes, by proper acetabular component positioning. We published the world’s first component positioning guideline that is supported by data. We named it RAIL: relative acetabular inclination limit. We then developed intraoperative x-ray techniques that allow us to achieve the RAIL in every case. We monitor all patients for excessive wear using blood ion levels. As a result, we have not created a single AWRF since 2008 (5 years, 2000 cases). Prior to 2007 the rate was 1% at 10 years.
Is Resurfacing Safe In Women?
Yes. The results are now superior to hip replacement. Early data from many centers indicated that women had a higher risk of failure due to femoral neck fracture, failure of acetabular ingrowth and adverse metal wear related failure (AWRF) than men did. I have now solved all of these problems. Femoral neck fractures are rare (1 in the last 2000 cases). A trispike acetabular component introduced in 2007 has eliminated the acetabular component failures in deformed dysplasia sockets (90% of dysplasia occurs in women). New knowledge about proper acetabular component positioning has allowed us to implant acetabular components to avoid AWRF (no new cases since 2008). The failure rate in women is now approaching the same low rate traditionally seen in young men.
Solving the Problems of Revision Failed Resurfacings
Our published results are nearly as good as for primary surgery. Others have also published excellent results for revision of hip resurfacing. Most reports on revision for the problem of adverse wear related failure (AWRF), however are poor. The worst report is from Oxford, with a 50% short-term failure rate. We have experienced a 100% success rate for AWRF by revising these failures with new large metal bearings placed correctly according to new implant positioning guidelines that we have developed.
Outpatient Hip Resurfacing
We are the first in the world to routinely perform hip resurfacing in an outpatient setting for selected young healthy patients. We began offering this in 2012 for selected local resurfacing patients. We have now expanded this offer to out-of-state patients. Minimally invasive techniques that allow a faster recovery, better pain control, and no transfusions have made this possible. Many people prefer avoiding a hospital to have their joint repaired. It is also more cost-effective. Local patients return directly home after day surgery, out-of-state patients stay in a hotel for 1-2 night before travelling home.