Which is better for your general health/life expectancy?

Patients with hip resurfacing have at least a 25% lower 10-year all-cause mortality than THR patients.

What does this mean? People of any age have a defined statistical chance of dying within 10 years. Insurance companies have developed these types of life expectancy tables for various populations. Of course, the 10-year mortality rate goes up with age. Data from the British and Australian Joint replacement registries have been combined with national mortality databases to evaluate the 10-year all-cause mortality of THR and Hip resurfacing patients.

When controlled for age, sex, general health status, and even socioeconomic status, hip resurfacing patients have at least a 25% lower 10-year mortality depending on the study. There are now 5 published scientific studies that demonstrate this effect. "Thought leaders" in THR continue to ignore this data and persist in performing THR in young patients. If the data had shown the opposite, I suspect that THR proponents would immediately claim that this was evidence that cobalt ions released from hip resurfacing implants were poisoning people.

The most important conclusion I make from these studies is that low levels of cobalt release are likely not harmful to people in the long run. It is even possible that low level  cobalt “supplementation” by these implants has some type of health benefit. The well known biological principle of hormesis states that some elements that are damaging at high levels are actually health promoting at lower levels. The case of free radicals and poorly conceived Vitamin E supplementation is only one example. But the best explanation of these findings seems to be activity. Patients who have hip resurfacing have been shown to be able to exercise more vigorously. Regular vigorous exercise has been shown to be the second most important lifestyle choice (after a healthy diet) that will affect health and longevity.

It is also possible that patients who seek out hip resurfacing are a group that is more interested in resuming vigorous exercise. A patient that is not highly motivated to exercise may be more likely to accept a THR recommendation from a local surgeon. Those who wish to resume vigorous exercise may be more likely to question the THR recommendation, do some independent research, and travel to a specialist surgeon who performs hip resurfacing. But one of the mortality studies mentioned previously did control for health status (Charlson comorbidity index). It is still conceivable that this index may not be fully able to capture a patient’s commitment to exercise.