Hip Information

Joint Replacement Information

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Hip	Ankle	Knee
Bone Conserving Hip Replacement Birmingham Hip Resurfacing (BHR) Hip Thrust Plate design from Switzerland Your next hip replacement	information to go here	and here

Bone Conserving Hip Replacement <Back to Menu> Hip replacement has become necessary for your arthritic hip: this is one of the most effective operations known and should give you many years of freedom from pain. Unfortunately, all hip replacements eventually fail - if you are fortunate to live long enough. High activity levels will wear the hip more quickly. Tiny bits of wear particles cause an inflammation around the hip, and bone stock is gradually lost. This is why the revision operation is more difficult than the initial operation. Fortunately there are new techniques of revision which improve bone stock by replacing bone, but it is better for the first operation to remove as little bone as possible - a bone-conserving hip replacement.
	This radiograph of an arthritic hip shows how the normal smooth surface of the ball-and-socket joint is lost. Cartilage that normally separates the bone has been worn away. In bone-conserving hip replacement the parts of the bone that rub together are resurfaced with metal implants. The cup and the femoral head used to be covered with a smooth layer of cartilage and acted as a ‘ball-and-socket’ joint. Since your cartilage is damaged (and as yet we do not know how to get it to re-grow) the ball and socket need to be replaced. Using special instruments, the damaged surfaces are removed. The cup is reamed up to a hemispherical surface. The femoral head is either trimmed or reamed down to an accurate shape to take its metal component. The new cup is a press-fit: bone will grow into the implant in the 6 weeks following hip replacement. For this reason the back of the cup is roughened and coated with a layer of hydroxyapatite, the mineral part of bone. There are two types of head replacement available:
	McMinn Design from Birmingham <Back to Menu> Mr. Derek McMinn developed this novel design in Birmingham. He was encouraged by the observation that a standard shape of hip replacement, designed by Mr. Ring, used a metal on metal bearing and survived over 20 years. Mr. McMinn applied this principle to a resurfacing design. In the X-ray you can see a head which caps the upper femur, and a socket also of metal which fits in the pelvic bone. This design has been in use for 5 years only but is very promising and 95% of patients are very pleased with it.

Thrust Plate Design from Switzerland <Back to Menu>

In this design a smaller diameter head is used and supported by a plate that is held by a bolt and short plate. It has been in use for over 10 years and has a proven record of survival in 80% of patients, with some improvements made subsequently.

This implant uses no cement. Many reports of uncemented hip replacements demonstrate a benefit from having the implant coated with hydroxyapatite, the natural mineral of bone. For this reason I arrange for these implants to be coated.

The major advantage of both these designs is that they allow a traditional hip to be inserted at a subsequent operation without any great difficulty. Both these bone-conserving hips are more expensive than the traditional replacement, and to counter this cost your stay in hospital is kept to a minimum, usually 3 or 4 days. This is possible through a combination of the surgical technique used and the team of nurses, occupational therapists and physiotherapists who will help you both before and following surgery.

What is the BHR(Birmingham Hip Resurfacing) Hip?

Mr. Derek McMinn and colleagues at the Royal Orthopaedic hospital in in Birmingham developed this novel design which offer patients a conservative and less traumatic alternative to Total Hip Replacement (THR). Mr. McMinn was encouraged by the observation that a standard shape of hip replacement, designed by Mr. Ring, used a metal on metal bearing and survived over 20 years. He applied this principle to a resurfacing design. In the X-ray you can see a head that caps the upper femur, and a socket also of metal which fits in the pelvic bone. This design has been in use for 5 years only but is very promising and 95% of patients are very pleased with it.

Major Advantages

The major advantage of this design is that it allows a traditional hip to be inserted at a subsequent operation without any great difficulty. Bone-conserving hips are more expensive than the traditional replacement, and to counter this cost your stay in the hospital is kept to a minimum, usually 3 to 7 days. This is possible through a combination of the surgical technique used and the team of nurses, occupational therapists and physiotherapists who will help you both before and after surgery.

Oswestry Hip Score <Back to Menu>

Your satisfaction following operation will depend on us providing as close a match as possible to your expectations. It is therefore just as important for you to have an accurate idea of what can be achieved as it is for us to provide as successful an operation as possible.

The hip questionnaire you completed is useful in determining the problems your arthritic hip gives you as well as defining which aspect of your symptoms you most want improved. Everyone is different. In the diagram below you will see a typical Oswestry hip score progression. Usually hip replacement is appropriate once the score has reached 60. Pain is the aspect of the score that can best be addressed, and through this you will become more active. Stiffness is difficult to help but fortunately this is the aspect of arthritis you probably find least distressing.

Following hip replacement there are a few days in which you feel little benefit (due to the pain of having an operation and the effects of the anaesthetic) but after this your hip score will rapidly rise. It will take you a week to learn to climb stairs, 6 weeks to be able to drive, and somewhere within this period you will be happy to take a bath on your own. In 3 months most people are back at work, free of a stick or crutches and sleeping on the operated side. Improvement continues for a year or more, as you can see from the chart.

Your next Hip Replacement <Back to Menu>

In due course it is probable that your symptoms will return, and a revision operation will be necessary. A traditional hip replacement is then most appropriate, and a cemented hip with a polished double taper has been developed at Oswestry (called the Centrafix) based on the original hip developed by John Charnley. It will only become apparent with time which type of conservative hip gives the best hip score, and which one lasts longest, but in my opinion there is around an 80% chance that these hips will last 15 years. The Centrafix has been in use for 5 years now and only one has so far failed. I would expect a good possibility of 80% lasting an average of 15 years. The deal is that you can be as active as you wish on the bone conserving hip, but once you have a traditional hip replacement, you must retire from active sports, and any physical work, to give the traditional hip the best chance of survival.

In due course it is probable that your symptoms will return, as shown in Chart 3 by the fall in the white line. A revision operation will then be necessary. A traditional hip replacement is then most appropriate, and a cemented hip with a polished double taper has been developed at Oswestry (called the Centrafix) based on the original hip developed by John Charnley.

CHART 3

It will only become apparent with time which type of conservative hip gives the best hip score, and which one lasts longest, but in my opinion there is around an 80% chance that these hips will last 15 years. The Centrafix has been in use for 5 years now and only one has so far failed. I would expect a good possibility of 80% lasting an average of 15 years. The deal is that you can be as active as you wish on the bone conserving hip, but once you have a traditional hip replacement, you must retire from active sports, and any physical work, to give the traditional hip the best chance of survival.
My approach is based on the problem that all hips fail and it is not possible to keep revising hips. You can only get 2 or 3 replacements. These bone conserving designs offer the possibility of adding one extra operation by removing as little bone as possible at the first operation. This means that whether it lasts 1 year or 20 years at least there is more bone stock available for the next operation.