In a nutshell there is no agreement on the best time for hip replacement surgery. The established view is to wait as long as possible but new materials and techniques along with a growing recognition of the problems associated with delaying surgery have led some surgeons to challenge the received wisdom.
All weight bearing implants have a finite life. As the two surfaces rub together they shed minute bits of debris. This debris sets up a reaction in the body which loosens the tight fitting implant. A loose implant is a painful implant. Sooner or later it will need to be replaced.
Wear is not just a function of time but of use. The more active the patient is the greater the rate of wear. Young people tend to be more active than their elders and will wear out their new joints faster. The argument therefore went that the best time for hip replacements with younger people was as late as possible.
Weight also plays a key role, with heavier patients wearing out their original and their replaced hips faster than lighter ones. A recent study carried out in Scotland showed that obese people are 4 times as likely to need a hip replacement than are their normal weight counterparts. The heavier the person the more pressure is placed on the weight bearing joints. 1kg of body weight puts approximately 4kg of pressure on the hip joint.
Revision surgery is a more complex procedure than the original operation and the more often it needs to be done the more difficult it becomes. Each time the joint is operated on there is a loss of bone stock together with damage to the surrounding soft tissue. This makes it harder to align the new implant precisely and correct alignment is crucial to prevent wear on the revised joint.
There is a higher chance of a serious post-operative complications following revision work. These include painful dislocation - necessitating a trip to A&E to have the hip replaced (or reduced as the doctors say), infections - which may involve the removal of the new implant so that the infection can be washed out and deep vein thrombosis - a potentially life threatening problem.
The best time for hip replacement surgery, it was agreed, was as late as possible.
The major problem caused by delaying surgery is the dramatic effect that conditions such as osteoarthritis have on the patient's quality of life. Yet the possible need for multiple revisions had be set against this. Especially true where younger patients were concerned. What was needed was a longer lasting implant.
With traditional implants the hip side of the replacement joint was made of polyethylene and polyethylene wears out relatively quickly. Replacing this with metal so that both sides of the joint were made of metal significantly extended the implant's life. Metal-on-metal implants are much harder wearing than metal-on-poly.
Better still was ceramic-on-ceramic where both sides of the joint are made from a type of metal oxide known as ceramic. This is the 2nd hardest material available in the world - the hardest being diamond. It has a very low rate of wear and unlike its metal-on-metal counterparts isn't associated with potentially hazardous metal ion debris.
Improvements are still being made to both new types of implant and so there is no definitive answer as to how long they will last. The expectation is between 25-30 years; about double the life of a traditional implant making it a viable implant for younger people.
Apart from the durability of implants concerns were raised about the physiological effects of delaying surgery and these too will affect the decision about when is the best time. As long as the joint is being used it will continue to wear away decreasing the chances of the patient being able to benefit from less invasive procedures such as hip resurfacing. The increased wear will also mean increased pain and further loss of mobility leading to loss of muscle mass in the affected leg which would impede recovery post-op.
With one leg not playing its part in weight bearing the rest of the body will need to compensate and so additional strain is put on the "good" leg which becomes the primary weight bearer. This can also lead to a twisting of the body and more wear on the spine.
With increasing loss of mobility the patient may start to gain weight which, as already noted, will lead to further stress on the joint.
Pain, loss of mobility, weight gain, deteriorating social life, inability to work are all issues the patient may have to deal with. These in turn can lead to psychological problems such as depression.
A University of Toronto study has shown that the "timing of surgery may be more important than previously realized and, specifically, that performing surgery earlier on the course of functional decline may be associated with better outcome." There may be an optimal time; healthier patients do better in surgery than unhealthy ones - they also recover quicker.
A survey of younger hip replacement patients showed that almost 30% of younger patients felt they would have benefited from having surgery earlier. Reasons included not having to endure severe pain and being able to spend more quality time with their children and family.
In the end it is the patient who needs to decide whether the benefits of living a fuller, more pain free life outweighs the risks of needing multiple revision surgery. In order to make a decision about what is the best time for their own surgery patients must have access to information about the risks involved and the chance to have an informed discussion with their surgeon.
General guidelines about the best time for hip replacement surgery are:-
Hip replacement surgery is probably the most effective surgery available. In a 2009 study carried out by the Office of Health Economics 91% of patients reported an improvement in their condition following surgery. With continuing work on the quality of hip implants it shouldn't be too long before a life time hip will be available for all.
We carried out a brief survey of hip replacement patients after they had recovered from their surgery focusing on whether they thought they had chosen the best time for hip replacement surgery.
33% of patients from the USA believed they should have had the surgery earlier, compared with just 1% from the UK.
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