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New Zealand faces a ''tsunami of knee replacements'' in the coming years, placing even more pressure on health services, a Dunedin academic says.
Consultant orthopaedic surgeon David Gwynne-Jones, Associate Professor of Orthopaedic Surgery at the Dunedin School of Medicine, said demand for knee replacements was ''catching up'' rapidly to hip replacements.
''We project that knees are potentially going to be double hips [in the coming years],'' he said.
Figures showed an increase in the number of total hip replacement (THR) procedures in New Zealand from 4114 in 1999 to 7481 in 2012, while total knee replacements had risen from 2429 in 1999 to 6345 in 2012. In Otago, there were 432 THR and 227 TKR procedures done in 2012.
Most joint replacements were a result of osteoarthritis, which came about through genetics and ageing, sports injuries and, increasingly, obesity, Prof Gwynne-Jones said.
''There is a strong association between obesity and knee arthritis, which relates to overload on the knee joints.
''A big person puts a lot of force through a small bone - in certain movements, you put up to five times your body weight through parts of your knee.''
While about 80% of joint replacements were done in people over 60 years of age, the obesity epidemic meant the population of people needing knee surgery would likely grow younger, he said.
Otago showed an increased demand compared to the New Zealand average, due to the region's ageing population and a backlog of patients due to demand exceeding provision of services in recent years.
The ''joint initiative'', introduced by the Ministry of Health in 2004 had raised Otago's contracted rate of joint replacement surgeries from 315 to 475 per year, but this was reduced in 2009 to 425 surgeries per year.
However, it appeared that the clinical need for surgery was significantly greater than this, Prof Gwynne-Jones said.
''I feel quite strongly that musculo-skeletal disease is not getting the attention it deserves, despite the high costs [of surgeries].''
Health Minister Tony Ryall said the latest data showed the Southern DHB performed a record 10,470 elective surgeries last year, more than 1900 of them orthopaedic operations.
The Government also had many initiatives aimed at promoting healthy lifestyles and reducing obesity and would be introducing a new Healthy Families NZ initiative later this year, he said.