In just over a decade, thousands more older New Zealanders will be a little bit bionic, as more and more hip and knee replacements are needed.
"Since there does not seem to be any other treatment for osteoarthritis that will surpass joint replacement surgery ... it would be safe to assume they would increase," Otago University medical researchers say in a report published in the New Zealand Medical Journal.
New Zealand's population is ageing but the elderly are remaining active. That means people are likely to demand new joints earlier to keep up their lifestyle, and those joints will be expected to last longer, the researchers said.
Increasing obesity may also be behind an increased demand for replacement knees.
The researchers estimate that by 2026 there could be nearly 18,000 hip and knee operations each year and the country should start preparing for that.
Currently there are around 13,000 such operations each year.
Another 80 surgeons would be needed to cope with the numbers.
In the US, knee replacements are predicted to increase 674 per cent by 2030.
However, in New Zealand it is believed the incidence of hip replacements will have increased 84 per cent and knee replacements 183 per cent between 2000 and 2026.
The lower numbers may be because New Zealand has been more proactive in dealing with the problem in recent years.
The researchers say fewer Maori were getting joint replacement surgery because of lower life expectancy and Maori are lower users of primary health care, where people generally get referred from.