2. DURABILITY

Hip resurfacing is more durable in any patient, any age, sex, implant size, or diagnosis.

This is more important the younger that you are because THRs fail faster in younger patients, and these patients need them the longest. People over 70 will probably not outlive a THR.

My current implant survivorship is 99% at 17 years. A large multi-center international study of hip resurfacing experts has demonstrated that in the hands of dedicated hip resurfacing arthroplasty (HRA) surgeons, the 10-year implant survivorship is 95% and the twenty-year implant survivorship is 90% in the most demanding young patients (age <50).

Joint Registries show a benchmark implant survivorship of approximately 95% at 10 years for total hip replacement (THR) (mean patient age 70). The failure rate increases with decreasing patient age. In patients under 50 years, the 10-year implant survivorship is only 80% with THR and the twenty-year survivorship is 50%.

In the British registry, HRA carries a benchmark implant survivorship of 92% at 10 years. HRA patients tend to be younger, therefore this is similar to age-matched THR patients. But most HRA in Britain is performed by surgeons doing this operation only 1-2 times per year. Most surgeons have much more experience performing THR. As a result, registry data for HRA are “contaminated” with results from inexperienced surgeons and results are therefore negatively biased against HRA.

In the Australian registry, men younger than 60 have better implant survivorship with HRA than THR, all other groups have better implant survivorship with THR. This has led many surgeons to proclaim that HRA should only be done in men under 60. But interestingly these same surgeons don’t recommend that THR should not be done in men under 60. Implant survivorship in registries is often overvalued as a means of choosing the best implant or operation. Registry data provides a benchmark for what the average surgeon can achieve. It might be better to choose a surgeon who can provide data that outperforms the registry.

HRA is a more complicated operation than THR and requires that a surgeon dedicate extensive time and energy to master it. Few have done this. After 1000 cases of any specific operation, most surgeons could be considered true experts. The multicenter HRA study demonstrates that surgeons dedicated to HRA can far surpass the implant survivorship benchmark of THR in younger patients. With my 99% 17-year implant survivorship, I have demonstrated that I can far surpass the registries and all expert surgeon series for all patients regardless of age, sex, or diagnosis.

In most studies of THR there is minimal difference in durability between the sexes. In most HRA studies women achieve lower 10-year implant survivorship than men. In my outcomes, this was true until 10 years ago when we managed to equalize the results.

For the diagnoses of osteonecrosis and dysplasia the durability is lower than for osteoarthritis for both THR and HRA. In my HRA outcomes, this was true until 10 years ago when we managed to equalize the results. Currently, my 10-year implant survivorship stands at 99% for all patient categories.

Implant survivorship is a statistical way to report how long an implant or operation is likely to last. If a surgeon (or registry) has data on when each operation was done and, on the dates, that all failures occurred as well as data on when patients have deceased, implant survivorship can be calculated using the Kaplan-Meier method. The estimate is only good for the number of years that have passed since the first operation was performed. This gives an estimate of how long an implant is likely to last. Registry results give average surgeon performance, individual data is required to determine how each surgeon performs compared to the average. If a surgeon tells you that a certain hip operation will last twenty years this is pretty meaningless. Most hip implants being put in today do not have any 20-year data to support such a claim. They need to tell you the odds of lasting 20 years and based on what data this estimate is made.

Please keep in mind that registry data represent an overestimate of actual implant durability. This error becomes greater as the study cohort of patients ages. This is because only failures that lead to revision are actually counted as failures by the registry. In a National Health System where waiting times for surgery are sometimes several years, the years a patient waits for revision count as “successful” years. If a patient elects not to have revision surgery, their case still counts as successful; this is more likely in older patients with more comorbidities.