Surgery better, but arthritis burden grows
Success rates for hip and knee replacements are rising, but so is arthritis, writes Lynnette Hoffman
BOB Saniga hasn’t exactly gone easy on his body over the years. A botched attempt to better his own Australasian raceboating record saw him hurled from a boat at more than 300 km/h, smashing his hip on the deck before bouncing along the water for hundreds of metres. Some years later a ski accident pounded that same hip once again.
He didn’t let either incident stop his active lifestyle, which included horseback riding, swimming and skiing, but it all started to catch up with him in his mid-50s, when car trips became ‘‘ excruciating’’ and dismounting from his horse was painful.
So 12 years ago, at the age of 57, Saniga had his left hip replaced. For the first two years afterwards, he was much happier, but then a constant nagging ache emerged, which lasted for four years — until a doctor noticed Saniga’s pelvis was tilted. His left leg was 10mm shorter than his right leg.
When doctors operated they found part of the hip prosthesis had broken, sending a peg shooting down into his femur with each step he took. The years of overcompensating meant he eventually needed his right hip replaced as well.
Still, Saniga says the replacements have been ‘‘ a godsend’’.
‘‘ If I do active physical work like using a chainsaw or climbing up and down on the tractor I get a little bit of soreness, but the next morning there’s nothing,’’ he says. ‘‘ A person (with a hip replacement) who doesn’t ride horses or drive a sports car every once in a while, or that sort of thing, probably doesn’t have any problems at all!’’
Joint replacement surgery is still not perfect, but it has come a long way even since Saniga first had it done in the mid-1990s.
New figures released from the Australian Orthopaedic Association’s National Joint Replacement Registry show that hip and knee replacements have significantly increased since the register began in 1999.
In addition, the number of subsequent operations on the same joint, ‘‘ revisions’’ (a marker for the rate of joint replacements that result in continuing problems) has declined.
Last year more than 64,000 Australians had hip or knee replacements — double the number from eight years ago. The numbers have increased by an average of about 7 per cent each year.
A report released by Arthritis Australia and Access Economics in August found that arthritis, by far the most common factor in needing a hip or knee replacement, is skyrocketing. The number of people with arthritis has increased by 700,000 in just six years and is now edging toward 4 million.
There’s a combination of factors at play in the burgeoning numbers of joint replacement surgery, says John Hart, an orthopaedic surgeon at Melbourne’s Alfred Hospital and an associate professor at Monash University.
Longer lifespans mean more people are reaching more advanced stages of the degenerative disease, when alternative treatments are less effective against the pain. Our thickening waistlines are also increasing the toll. Athletes are playing sports more vigorously and at a higher intensity than they once did, leading to an increase in younger patients. And there’s an increasing awareness of treatment options, he says.
Meanwhile, advances in general medicine and anaesthetics have made joint replacement surgery available to people who would have been turned away a decade or two ago, says doctor John Batten, chairman of the National Joint Replacement Registry.
‘‘ It’s still a last resort, but we’re able to offer it to people who would not otherwise have been considered,’’ he says.
Once upon a time it would have been too dangerous to perform the operation on patients with severe heart or kidney disease, but improvements in treatments and techniques mean that’s no longer the case. More people in their 80s and 90s are now healthy and well enough to benefit from the operation. And technology that makes hip replacements more durable has opened it up to younger patients as well, he says.
Despite negative publicity following a 2001 recall of prosthetic hips, doctors say the surgery is safer and more reliable now than ever. The longer you have a hip or knee replacement, the more likely it is that you will need further surgery. In 1998, 14.6 per cent of hip replacement surgeries and 10 per cent of knee replacement surgeries were revisions.
Those figures have fallen slowly but steadily. Last year 12.4 per cent of all hip replacement surgeries and 8.1 per cent of knee replacement surgeries were revisions. Overall there were 641 fewer knee revisions and 670 fewer hip revisions — saving an estimated $33 million in operating costs.
While an initial joint replacement surgery costs an average of between $12,000 and $15,000, revisions are considerably more expensive, costing an average of $25,000 to $30,000, Batten says.
‘‘ Revision operations are bigger, more complex and more dangerous operations. They need more expensive components. The device has already failed, so you’ve got to do a lot more to get it going,’’ he says.
Hart says improvements in the design of prostheses mean the surgery is now more suitable for younger patients who will be more demanding and active, though they are still likely to wear the hip out faster than someone who is less active.
‘‘ New materials used to make the prosthesis have more cross-link of fibre so they are more resistant to wear,’’ Hart says. ‘‘ The head size of the prosthesis is now bigger as well, which makes the joints more stable and dislocations less common.’’
Meanwhile, the operations themselves are also becoming more efficient and less invasive. ‘‘ The changes also allow us to approach the surgery from the back of the joint, where tissues are more soft and compliant — so there is less soft tissue damage and it allows the patient to recover more quickly.’’
He and Batten say the improvements have translated to a drop in both length of surgery and the amount of time patients spend in hospital. ‘‘ Ten years ago the average hip replacement required 10 days in hospital and a two-hour surgery. Now the surgery takes about an hour and you will be home in five days or less,’’ Batten says.
But despite the improvements, complications still occur. Infection is rare, but occurs in up to 1 per cent of cases. Deep vein thrombosis, clots in the veins in the limbs, can be a problem, and dislocations, loosening and general wear-and-tear lead to patients needing revisions.
In fact, Hart says that the trend toward declining revision rates will probably reverse again in the future.
‘‘ As more hips and knees are being replaced, we will likely see more revisions. We’re being challenged by the number of younger people who are needing replacements and are putting more demand on the prosthesis and wearing it out more quickly — and they live longer,’’ he says.
‘‘ The problem of obesity is also growing, and extra weight puts more stress on the joints. People who are morbidly obese have higher revision rates and more soft tissues complications because of increased load, and they don’t do as well.’’
The federal Government has asked the registry to expand its area of interest to include replacements affecting the shoulder, elbow, wrist and spinal discs.
The widening of the registry’s scope, due to take effect later this year, will allow success rates in these areas also to be tracked, yielding data to improve success rates further.
Broken: Bob Saniga with his first artificial hip joint, which failed. Revision surgery was needed