Hip hop - your questions answered.

What is hip hop?

Hip hop is a severe pain in an artificial hip that forces you to hop on your good leg to avoid it. Alas, many British patients suffer in silence because they think if their hip fails early, it must be their fault. On average, 10 per cent fail to make it to 10 years but some pack up much sooner, requiring a bigger and more painful revision operation.

And whose fault is that?

It's either a problem with the hip itself or the person putting it in.

Let's take hips first. This Capital prosthesis that's just flunked. The Independent said "it was never tested".

Have I got bad news for you. There are more than 60 different types of hip prosthesis used in the UK - only a handful have good published results over five years and only two have good long term (over 10 years) results - the Charnley and Stanmore implants.

So there are more than 50 others floating around in people's bodies that could all go the same way as the Capital?

I think you're being unduly alarmist. Hip replacements are one of the big success stories of modern medicine and 90 per cent of them in the UK seem to go extremely well.

Why seem?

Well, we don't have an obligatory national register of orthopaedic implants like they do in Sweden, and without it most orthopaedic surgeons haven't got much of an idea how their implants do or which ones are likely to fail prematurely.

But surely, if you're hammering great lumps of untested metal into the top of someone's thigh bone, the least you could do is follow it up?

You obviously haven't met many orthopaedic surgeons. Most are far too busy doing the operations to take time out to trace the long-term consequences. However, some enthusiasts do it meticulously. John Charnley created a prothesis in the Sixties, provided the tools to put it in, trained other surgeons and followed up every single operation.

So we know it works?

Absolutely. Also, in East Surrey, they keep a regional X-Ray register of all hip operations to spot which prostheses work well and which don't. And at the Nuffield Centre in Oxford, they've used an X-ray technique called RSA which detects minute movements of marker beads inserted at the time of the operation. This can predict which new prostheses are likely to fail far more quickly than conventional X-rays.

Hang on. If the older prosthesis have good results and never been bettered, why bother with expensive new ones?

What a naive little world you inhabit. As one consultant put it, "Drug companies are not much different from arms manufacturers. They fly us all out to Florida, pamper us, brainwash us and then get us to use their latest fancy prosthesis. Whether we like it or not, we're all in their pocket."

Shouldn't Mr Dobson just tell everyone to go back to Stanmore or Charnley?

If only it were that simple. Some orthopaedic surgeons like trying out every new gadget on the market but others are creatures of habit and prefer to stick to what they know.

So, if they got hooked on a dodgy prosthesis from an early age, it's very hard to wean them off even in the face of the evidence. One consultant explained: "I personally would never use the Ring Hip but I know senior surgeons who still do. It's all they know."

What about junior surgeons?

A study published in the Journal of Bone Medicine in 1996 found that Charnley and Stanmore replacements carried out by junior trainees were 11 times more likely to need a revision compared to consultant operations. Anecdotally, a consultant told me that when he started operating he was left to do hips on his own and his registrar had to do a ward round in the evening to pop all the hips back in that had fallen out.

So what can I do to improve my chances?

In the NHS, nearly half of operations are done by juniors. If yours is, ask for it to be closely supervised by a consultant. Make sure the consultant does lots of these operations and ask to see an audit of the results. He'll probably go purple but it's worth a try.

Failing that, ask the health authority to provide the information. Your hip is your future, after all.

What about the prosthesis?

You can't go wrong with Charnley or Stanmore, although they're hard to find because they've all been modified. Some modifications are good (e.g. the Elite) others are bad (e.g. the Capital). In the Exeter region, the Exeter hip has good results. Also, they wouldn't stick any old rubbish in the Queen Mum. She had the Furlong.

How do you know all this?

Because we covered it in the last series of Trust Me, I'm a Doctor. The new series kicks off with all you need to know about cancer vaccines, cranberry juice and obesity on 3 March, BBC2, 8pm.