Knee and Hip Joint Replacement Surgery

Hip and knee replacement procedures have become routine in the UK, with over 160,000 operations performed every year, according to the National Joint Registry. Improvements in surgical technique and aftercare have increased the chances of success and patients now experience a much more rapid recovery.

Technology innovations in the development of prostheses have also increased implant durability and patients can now expect their replacement hip and knee joints to last many decades.

The history of hip replacement and knee replacement surgery

In the 1960s, Sir John Charnley performed the first successful hip replacement operation to relieve the symptoms of osteoarthritis. The femoral head of the hip joint was removed and replaced with a socket and ball implant composed of polythene and steel and anchored with acrylic cement.

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Aware that the materials used for the moving parts would wear out over time, Charnley would not perform the procedure on younger patients.  The debris produced by the bearing can damage the bone and lead to loosening of the implant, leading to the need for the joint replacement to be re-done (revision).  For a long time, surgeons tried to reserve hip and knee replacement for older patients, to try and ensure the joint would last the rest of their life.

There have been great advances in material technology over the years.  We now have highly cross-linked polyethylene and advanced ceramics, which have greatly reduced the wear rate compared to the materials Charnley had available.  This means that we can have more confidence implanting joints in younger patients, in the knowledge that these materials mean the joint has a good chance of lasting in excess of 20 years.

Prior to knee replacement surgery, various materials were inserted into the knee joint to try and reduce arthritis-related pain with disastrous results. In the early 1950s, surgeons tried to insert a simple hinged design by hammering and chiselling a space in the knee joint, again with little success.

In the 1970s the condylar knee prosthesis was developed, which was more anatomically correct and is the starting point for all modern day knee implants, most of which have very similar designs, basically re-lining the joint.  Designs and instrumentation have been improved, to better restore the anatomy of the joint and, along with modern materials, this had led to good knee function being achieved, with the joint having a very good chance of lasting in excess of 15 years.

The most important advances in hip and knee replacement in the last 10 years have been in peri-operative care.  We now have well established enhanced recovery programmes, which mean that patients are able to get home much sooner.  There is good data which tells us that the complication rate is reducing as a result of this.  Anaesthetic and pain management techniques mean that patients are much more comfortable after their operation and people are often up and about on the day of surgery. Length of stay has reduced to between 2 and 4 days in most cases.  All this means that people get back to feeling normal much more quickly.

Hip & Knee Replacements: Frequently Asked Questions

Do I need hip or knee surgery?

The knees and hips are the body’s largest, most complex joints and they must support our full weight, as well as provide us with the full range of movement we take for granted. Congenital or growth problems and injury can all affect how our joints function, but wear and tear is the most common cause of joint pain and loss of mobility .

There are a number of non-surgical options that Mr Simon Bridle will first explore with you.  These include physiotherapy to teach you specially-targeted exercises, pain medication and injections into the joint.  If your condition fails to improve and you find your ability to perform even normal, everyday activities is affected then you may be a candidate for a joint replacement procedure.

X-rays will normally give enough information to make the diagnosis and the decision to recommend surgery.  Sometimes an MRI will be needed to give more information.  Occasionally a CT scan may be necessary, to better define the anatomy of the joint, usually in bore complex cases where there may be an underling deformity, which may require different surgical techniques or implants. Mr Bridle will then advise you as to whether a total or partial joint replacement procedure is your best option.

What will happen before my operation?

You will be seen in a pre-assessment clinic at the hospital where you are having your operations.  You will be seen by a nurse, who will check your general health, do some blood tests and often an ECG (recording of your heart).  They will make a report to your surgeon and anaesthetists. Occasionally, arrangements will be made to also see the anaesthetist, if there are any particular issues.  You will also be given information about what to expect when you come into hospital and how to best prepare yourself for the operation

What happens during a hip replacement procedure?

Hip replacement procedures take a couple of hours and are usually performed under a spinal anaesthetic along with sedation.  There is very good evidence that this is the best and safest way to do the operation.  This will be discussed with you at the pre-assessment and with your anaesthetist. In a hip replacement, the hip is dislocated and the femoral head removed.  A new titanium socket is fixed to the pelvis and a metal stem is implanted into the femur, with a ceramic head.

What approach does Mr Bridle use?

Mr Bridle recommends a posterior approach to the joint.  This involves removing a small muscle from the back of the joint, which is repaired at the end of the operation.  There will be a scar in the buttock approximately 15cm long, which is closed with a stitch under the skin and tissue glue.  There has been a lot of publicity about minimally invasive surgery and surgery using the anterior approach.  At the moment the evidence in the orthopaedic literature is that these provide no advantage in pain relief or long-term function.  Mr Bridle has looked carefully at these techniques and does not recommend them.

Should I have a hip resurfacing?

Resurfacing the hip with a metal on metal implant became very popular about 15 years ago.  Results of this technique have been generally very disappointing and many designs have been withdrawn.  The small amount of metal debris which is produced can damage tissue and bone, leading to early failure and need for revision in some patients.  Mr Bridle does not recommend hip resurfacing in anybody as a result of this.  Results may be as good as conventional hips in middle-aged men, with large bones and this type of patient may be a candidate, but there is no evidence that a resurfacing functions any better, or lasts any longer, even in this group.

How is the artificial hip fixed?

Acetabular component

This is the part that goes into the pelvis.  In most patients, Mr Bridle uses a component fixed without cement called the Trident. In patients over 75, there is evidence that cementless fixation has a higher early failure rate, so cement is often used in these patients.

Femoral component

This is the part which fits inside the thigh bone.  Fixation can be equally well achieved with or without cement.  Mr Bridle recommends the cemented Exeter stem, which is made out of stainless steel, for a number of reasons.  There is a very wide range of sizes and along with the cement which is used to fix the component, allows the surgeon to very accurately reproduce the normal anatomy of the hip.

The orthopaedic literature shows us that this component performs will even beyond 30 years.  All hip replacements performed in England are now recorded on the National Joint Registry (NJR) and the Exeter is among the best performing femoral components.

All hip and knee implants are rated by the Orthopaedic Data Evaluation Panel (ODEP), based on the long-term results of the implant.  The Exeter is rated 10A*, the best rating available.

If revision is required this can often be achieved by putting a new stem into the old cement, which is very straightforward.  Removing cementless femoral components can be very challenging and time-consuming, often damaging the femur.

What bearings are used?

Mr Bridle uses a highly cross-linked polyethylene bearing, which lines the acetabulum and a Biolox ceramic femoral head.

The acetabular component is made out of a material called X3, which is a specially treated polyethylene and has a very low wear rate.  Studies have shown that the wear is almost undetectable at 5 years from implantation.  Mr Bridle prefers this to ceramic for the acetabulum as there is a risk of these squeaking, which can be quite disconcerting!

Biolox is a very strong, low friction material, ideal for the head component.

What happens during a knee replacement procedure?

Knee replacement procedures take a couple of hours and are usually performed under a spinal anaesthetic along with sedation.  There is very good evidence that this is the best and safest way to do the operation.  This will be discussed with toy at the pre-assessment and with your anaesthetist.  During a total knee replacement procedure, both sides of the knee joint are replaced; the kneecap is moved to the side and the damaged ends of the femur and tibia are cut away, using specialist precision instruments to ensure good alignment and an accurate fit of the components.  The cruciate ligaments are removed, but the main ligament of the knee are kept intact.  The femur, or thigh bone, is then replaced with a curved replacement and the shin bone or tibia is replaced with a flat plate.  The components are cemented in.  A shaped polyethylene bearing is fixed to the tibial component and this articulates with the curved femoral component.  The back of the kneecap is relined with polyethylene in most cases.

Knee replacements are painful operations. We do our best to minimise this. The spinal help with this in the early post-operative period.  We also put local anaesthetic into you knee during the operation and this can provide sustained pain control after the operation.

What implants will be used?

Mr Bridle uses the PFC knee replacement system. This has an ODEP 10A* rating and is one of the best performing implants in the NJR.  He has been using this system for over 15 years.

What will happen after my knee replacement?

You will be able to get out of bed very soon after the operation – often on the day of surgery.  This will be closely supervised by the nursing staff and physiotherapists.  You will be taught to walk with crutches or sticks.  You will be allowed to take full weight through your leg straight away.  Usually ice and special cooling devices are used to keep the swelling down and the physiotherapist will help get your knee moving.  You will be in hospital for between two and four days.  By the time you go home you will be confident walking and be able to do stairs.  The physiotherapist will recommend a plan for your rehabilitation, including need for out-patient physiotherapy.  Most people stop using their walking support between two and six weeks.  Patients can get back to driving by between four and six weeks.  By three months we would normally expect patients to be getting back to light sporting activities. 

Will I need revision surgery in the future?

Hip and knee replacements are usually highly successful orthopaedic procedures, producing excellent results. Patients typically experience a dramatic reduction in pain and within just a few weeks of your operation you should be independently mobile and able to return to all normal activities in a matter of months.

Joint replacements do wear out, as the small amount of wear debris produced can eventually cause them to loosen.  Mr Bridle is seeing more young active patients in his practice and there is a chance that these people will need further surgery at some point in their life.  The materials we now have available mean that we are confident that most hips and knees will last at least 20 years.

Joint replacement surgery is a major, complex operation and there is a risk of complications. These range from very minor, temporary problems to more serious complications such as infection.  This occurs in well under 1% of cases but this will almost always require further surgery to treat it.

What are Mr Bridle’s results?

For the last 10 years, all Mr Bridle’s activity has been recorded in the NJR.  This now includes data on over 900000 hip replacements and over a million knee replacements!  Mr Bridle has 967 hip replacements and 427 knee replacements in the NJR and has done 83 hips and 55 knees in the last year.  He has done 462 hip revisions and 81 knee revisions. His numbers of hip replacement and revision cases are well above the national average.

Over the NJR period his revision rate for hip replacement is 0.67%.  This has been audited and most of these are in complex cases.  His revision rate for knees is 0.6%.  These figures are well below the national average and among other thing reflect his choice of well performing implants over the years.

Audit from the Elective Orthopaedic Centre indicates no deep infections or dislocations over the previous 12 months.