 
The hip joint
In basic terms, the hip joint consists of a cup or socket in the pelvis (called the acetabulum), and a ball on the hip bone (femur). These join together to form a joint, and are covered by cartilage. The hip joint has a lining (called the synovium), and lubricating fluid within the joint.
What is hip arthritis?
There are many different types of hip arthritis, but the most common is called osteoarthritis. It involves inflammation in the hip joint, and wearing out of the cartilage surfaces of the hip joint.
Not all hip pain is due to osteoarthritis. There are other forms of arthritis, such as rheumatoid arthritis, and other causes of hip pain such as disruption of the blood supply to the hip joint.
What causes osteoarthritis?
In many cases there is no clear cause. It is more common as we get older. In some cases being overweight can contribute. Genetics may also play a role. This is an area of a lot of ongoing research.
In some cases, arthritis can develop from a previous problem with the hip, such as childhood hip disorders or past injuries. There is also increasing recognition of other causes of hip arthritis which were not apparent before, such as impingement or rubbing of the ball part of the hip (femur) on the cup part of the hip (acetabulum).
Symptoms
Osteoarthritis typically causes pain and stiffness. Hip pain is often felt in the groin, buttock, or thigh. It will tend to be worse with activity, and settle with rest. It may disturb you at night. Walking can be become restricted as well as other activities, and some movement tends to be lost in the hip, which can lead to problems such as reaching down to put shoes and socks on.
Hip arthritis will tend to get worse over time, although not always, and each person is different regarding how quickly their arthritis may progress, and what symptoms they have from it.
Diagnosis
Most times the diagnosis is suggested by a doctor taking a history and from examining the hip joint. It is usually confirmed by taking an X-ray of the hip. Occasionally more specialized scans are needed to confirm the diagnosis or to rule out other conditions. These scans include bone scans, CAT scans, and MRI scans.
Treatment
Non-operative treatment
Not all hip arthritis needs an operation, and early or mild forms may be able to be treated with other measures.
    
Surgery
In most cases for hip osteoarthritis (the commonest form), if you do require surgery it will consist of a hip replacement. In some other conditions, other surgery may be appropriate.
A hip replacement is a reasonably big operation, which has potential complications, but the good news is it is generally very successful at alleviating pain.
Basically the surgery involves replacing the worn out portions of the hip joint with artificial materials. In the socket portion an artificial cup is put in, and on the ball part of the joint a metal stem is placed which sits inside the thigh bone or femur. In between the two parts is an artificial surface, of which there are different types, to act as the moving part.
  
What are the implants made of?
Most of the implants we use are made of titanium. This is used for the metal cup and for the metal stem that is fitted into the thigh bone. Occasionally, other implants are used, such as Cobalt-Chrome or stainless steel.
The moving parts are usually made of a ceramic ball which moves against a polyethylene (or plastic) surface. There are other forms of moving surfaces such as a ceramic ball against a ceramic liner, or a metal ball on a plastic liner, or a metal ball on a metal liner. Each form has its own advantages and disadvantages, and no one combination is perfect.
How are they fixed in place?
The implants are fixed to your bone by being press-fit, or wedged into the bone. Sometimes additional screws are needed to hold the metal cup in place. Over time, your own bone will grow into the implants to stabilize them over the long term. Occasionally, we will use cement to fix in the metal stem into your thigh bone. These are standard techniques which are used world-wide and have reproducibly good results.
 
How long will it last?
Each hip replacement and person is different, and we cannot specify exactly how long each hip will last. At least 90% of hips will last 10 years, and some have lasted longer than 20 years. Some things will wear out a hip quicker, such as overactivity.
Most activities are OK after a hip replacement, although we would advise you against high impact activities such as jogging or high level competitive sports. Golf, walking, riding a bike, swimming and social tennis are normally fine.
When is the right time to have surgery?
In the majority of cases, hip replacement for osteoarthritis is an elective procedure, and doesn’t need to be rushed into.
Generally, the right time to have a hip replacement is when your symptoms are bad enough to interfere with the activities you want to do, and you cannot control the symptoms with the measures mentioned previously.
Older age is generally not a barrier to having a hip replacement. If you are very young, the decision should be carefully considered, as there is a chance the hip replacement may wear out over time and need re-doing. Re-do surgery tends to be a larger operation, with higher risks involved.
What is involved?
Once the decision to proceed with a hip replacement has been made, arrangements will be made to make sure you are in the best condition possible for a large operation. This will include blood tests, a heart tracing (ECG), and generally a CXR and special X-rays of you hip to allow us to work out the best size hip to put in. A urine test will be taken to check for infection. You may need to see other specialists if you have other medical problems such as heart problems which need to be stabilized beforehand. We will see you again after these tests are completed to check them, and discuss the surgery again.
Generally you will go in to hospital the day of surgery, although occasionally admission the night prior may be appropriate.
SJOG Murdoch and Subiaco offer a pre-admission service where you will meet or be contacted by a nurse from the hospital to discuss your surgery with you.
The length of stay in hospital changes from person to person. Most people will be in hospital for between 5 to 7 days, although occasionally shorter or longer times are appropriate or needed.
What is the recovery like?
The operation pain will settle reasonably quickly (within a week or two), but full recovery will take much longer. While a lot of the improvements are early on, it can take up to one year after for you to fully recover and for your muscles to rehabilitate.
For the first 6 weeks, you may need crutches, and should avoid bending the hip beyond 90 degrees, and sitting in low chairs. You will need special equipment (which will be organized while you are in hospital) such as shower and toilet chairs, and seat wedges.
Generally, you should not drive for up to 6 weeks after surgery, although we will advise you regarding this.
For work, most ‘desk-jobs’ will be OK after 4 to 6 weeks. More active work, for example if you are on your feet most of the day, can take longer (e.g. 3 months) to return to. You should reconsider heavy manual work or labouring after a hip replacement.
What can I do beforehand to be as ready as possible for the operation?
Be informed. We will give you information to read about the operation and what to expect.
Keep active, within the limits of your pain. An exercise program may help.
Lose weight if you are overweight.
Stop smoking, and reduce your alcohol consumption.
Check with your doctor about medications you are on (including natural remedies). Some may need to be stopped.
Keep your skin in good condition, and avoid any cuts on your skin just prior to the operation.
Have your teeth checked to make sure there is no infection or any dental work that you may need doing (it is much better to have this done before an artificial joint).
Organize things at home, and arrange for some help after the operation. This may include things such as cleaning your house beforehand so you don’t have to do it after the operation, stocking up on shopping beforehand, etc.
Sometimes a blood transfusion may be needed after surgery. Consider and discuss with your doctor if you feel strongly about donating your own blood beforehand.
What are the potential risks?
Being major surgery, a hip replacement does entail some risks, which include:
- The anaesthetic. Obviously this has very real, but uncommon risks, such as the chance of heart problems etc. or even death, although this is highly unlikely. If you have questions or concerns it is important to talk to your doctor and anaesthetist.
- Infection. The risk is only 1%, but if it does occur, it can mean further operations and treatment with antibiotics for a long time. Sometimes we may even need to remove the artificial joint.
- Dislocation. This occurs in 1% or less of cases. The artificial hip joint pops out and needs to be put back in place, usually in a hospital. Occasionally, further surgery may be necessary.
- Leg length discrepancy. It may be difficult to get your leg lengths equal, and sometimes we have to find a balance between the risk of your hip dislocating and placing additional tension on the leg by making it longer. Often if one leg is felt to be slightly longer or shorter , it will settle over time and become unnoticeable. Most of the time the difference is only a few millimetres.
- Nerve injury, which is very uncommon (less than 0.1%).
- Blood clots can form in your legs, which may break off and lodge in your lungs and cause problems. You will need to take medications for 6 weeks after surgery to reduce this risk.
- Bleeding which may mean that you need a blood transfusion.
- Bruising of the wound, which is not normally dangerous.
- Wearing out of the hip replacement, and the potential need for re-do surgery, which is usually a bigger operation, with higher risks.
- Limp, which normally resolves, but can persist for a year or so.
- There are other risks which are less common, but will be discussed with you or listed in information given to you prior to surgery.
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