Hip Replacement

Introduction

The hip replacement operation counts as one of the greatest medical advances of our time. Approximately 50,000 hip replacements are performed in Britain every year. Although the success rate is high, your new hip will not have the same range of movement of the original joint, but you should eventually be able to return to your previous level of activity.

The hip is one of the body's largest weight-bearing joints. Hips consist of two main parts; a ball (femoral head) at the top of your thigh bone that fits into a rounded socket (acetabulum) in your pelvis.

Ligaments connect the ball to the socket and provide stability to the hip joint. Normally, the ball moves smoothly in its socket on a lining of shock-absorbing cartilage.

But if the cartilage becomes worn or damaged through injury, arthritis or other conditions, the joint becomes stiff and painful and everyday activities, such as walking or even getting in and out of a chair, can be very difficult.

What is a hip replacement?

Artificial hip joints are fitted to relieve the pain that stems from hip joint disease, including osteoarthritis and rheumatoid arthritis of the hip, injury, congenital (inherited) defects of the hip or Paget's disease, which causes weakening of the bones.

During a hip replacement (also known as total hip replacement or THR), the existing hip joint is completely replaced.

The surgeon removes damaged cartilage and bone from your hip joint and replaces them with artificial parts (prosthesis). The surgery itself involves cutting away the head of the thigh bone and inserting a metal or ceramic ball on a stem. A cup is fixed into the socket of the pelvis and the ball is placed into it.

Benefits:

• Long lasting, with a target life of 10 years
• Relieves pain
• Increased mobility, better quality of life

Drawbacks:

• Certain post-operative complications may mean repeat surgery
• General anaesthesia may cause side effects
• Unable to take part in vigorous sports, such as running or football, because of the risk of dislocation

What is hip resurfacing?

Hip resurfacing is an alternative to total hip replacement. It is also known as metal on metal (MoM) resurfacing.

The procedure involves replacing the worn surface of the hip joint, ie the top end of the thigh bone and inside the socket of the hip bone, with metal plating. This procedure removes far less bone than in a total hip replacement.

Hip resurfacing is generally considered a better option for younger patients who are expected to have a repeat procedure later in life. It is sometimes recommended to people with advanced hip disease.

Benefits:

• Less bone is removed than in total hip replacement
• Speedier recovery
• Less risk of dislocation, allows patient to take part in more vigorous sports such as skiing
• Increased mobility, better quality of life

Drawbacks:

• Technique is relatively new, long term results not yet known
• Not suitable for everyone (particularly those with low bone density or osteoporosis)

What are artificial hips made of?

There are more than 60 different types of artificial hip available either made of metal, porcelain or plastic.

Normally the cups are made of plastic (although they can be made of metal or a ceramic material) and the ball is normally made of metal.

Some artificial parts need a special cement to keep them in place, some may be coated with a chemical that encourages them to bond with the bone naturally, others may be fixed directly to the bone with screws.

The National Institute for Health and Clinical Excellence (NICE) recommends that surgeons only use types of new hip that have been shown to last at least ten years.

What are the benefits of a hip replacement?

Once the joint has healed, your new hip will give you increased leg strength, movement and mobility. You will be able to enjoy not only everyday life, but also recreational activities such as walking, cycling or playing golf without constant pain.

If you look after your new hip, it should last at least 10 years (possibly longer) but repeat procedures are possible. New hips are more likely to fail in younger people who play sports and are generally more active. For many older patients, the hip replacement will last for the rest of their lives.

Are there alternatives to surgery?

Hip replacement or resurfacing is only recommended for people with severe hip damage, when the pain and disability are having serious effects on normal daily activities.

Before considering surgery, your doctor will recommend appropriate alternatives such as painkillers, anti-inflammatory medication, walking aids, physiotherapy. Many people with severe arthritis choose not to have surgery and can still function adequately.

The hip replacement operation

A hip replacement operation takes about two hours. It will be performed under a general anaesthetic (so you will be asleep during the operation and not feel any pain) or a spinal or an epidural anaesthetic, which numb the lower half of your body (you will remain awake during the operation but will not be able to see the surgery).

The operation involves replacing the 'ball' of your thigh bone with a metal ball. The metal ball is attached to a metal stem that fits inside your thigh bone. A plastic and metal socket is implanted into your pelvic bone replacing the damaged socket.

Together these artificial parts, which mimic the natural design of your hip, function like a normal hip joint.

Minimally invasive two-incision surgery

Minimally invasive hip replacement allows the surgeon to perform the procedure through one or two small incisions. Because the incisions are so much smaller than in standard hip replacement, damage to the surrounding tissue is significantly reduced.

The benefits of this technique include less pain and speedier recovery. Unfortunately because this is a relatively new technique, long-term results are still unclear. Your doctor will explain the risks and benefits.

Possible complications

Many thousands of hip replacement operations are successfully carried out every year, but as with any surgery, complications can occur. It is important to be aware of potential complications, but also to keep them in perspective.

The most common problem after surgery is loosening of the joint. This can be painful and could make your hip unstable. Although this can happen at any time, it is commonest 10 to 15 years after surgery and you may need another operation to replace it.

Loosening can be due to thinning of the bone around the implant, or caused by the shaft of the artificial part becoming loose in the hollow of the thigh bone.

Most people's artificial hips last at least 10 years but there may come a point when it becomes worn and stops working properly. Another replacement might be necessary.

Other complications, although less common, include:

• Infection- the wound or new joint can get infected. Specially ventilated operating theatres with 'clean air' systems are often used to reduce the chances of infection. Taking antibiotics at the time of surgery also helps reduce the risk of infection. Should a deep infection occur, you may need further surgery to replace the infected hip with a new one
• Dislocation- the ball may come out of the socket. If this happens, the hip needs to be put back into place under anaesthetic
• Blood clots- can form in deep veins of the leg (deep vein thrombosis or DVT). Your surgeon will prescribe measures to reduce this risk including special stockings, exercises and medication
• Change in leg length- it is possible for the leg that was operated on to become slightly longer. Wearing a raised shoe on the shorter side can correct the problem
• Joint stiffening- sometimes the soft tissues around your hip joint can harden (a process known as ossification). There shouldn't be any pain but it may reduce mobility. Your doctor may prescribe medication or radiation therapy to prevent this from happening.

Recovery

Depending on how fast you recover, you should be able to go home about a week to 10 days after the operation. By the time you leave hospital you should be able to climb stairs, walk and do gentle exercise.

A physiotherapist will explain what you should and shouldn't do following surgery, as well helping you get used to the walking aids and teaching you exercises to help strengthen your hip.

An occupational therapist may also be available to advise on home adjustments such as a raised loo seat, a hand rail in the shower or devices to help you dress.

As with all major surgery it takes time to fully recover, but within about three months you should feel relatively back to normal. You will be given an outpatient appointment, usually between six and 12 weeks after surgery, to check up on your progress.

Gentle exercise, such as walking and swimming, is a must and will get your new hip working. You can expect to get back to doing all your normal activities within a year.

Other post-operative considerations:

• Returning to work - you will probably need around six weeks off, but if your job involves a lot of standing you may need three months off
• Driving - should be possible within six to eight weeks
• Sex - your surgeon will probably advise waiting at least six to eight weeks
• Avoid bending or twisting at the hip, lying on your side, sitting in low chairs, crossing your legs or bending over more than 90 degrees

It may be worth noting your new hip may activate security metal detectors in airports and some buildings.

Clickthrough information and support links:

Arthritis Research Campaign
The National Joint Registry