Hip surgery

A total hip replacement is a surgical procedure in which the arthritic or damaged joint is removed and replaced with an artificial joint (prosthesis).

Although an artificial hip will never be better than a normal healthy joint, in the vast majority of cases surgery will alleviate pain and stiffness and allow you to return to general daily activities, generally including sports and moderate physical work.

Hip replacements have been performed for over 50 years and are still considered to be one of the two most successful surgical procedures. At least 50,000 hip replacement operations are carried out in the UK each year, with a success rate of 97%. Around 96% of hip replacements last for ten years, while at least 85% last for 20 years.

At The London Hip Unit, we have been using either ceramic on ceramic or ceramic on highly cross linked polyethylene bearing couples for over 20 years, and because of this, we can report significantly higher survivorships with well over 90% surviving 20 years.

Primary (first time) uncomplicated total hip replacement surgery at The London Hip Unit can be performed using a minimally invasive technique and computer aided navigation or robotic assisted surgery is employed in certain cases.

Surgery is carried out through a single incision of around 6-10cm (compared to 20-30cm in conventional surgery). Miss Muirhead-Allwood helped to develop this technique, which is only available by a limited number of experienced surgeons in the UK. Mr Hutt also performs hip replacement surgery through the direct anterior approach (DAA) in suitable patients.

The benefit of these techniques is that less supporting tissue is disrupted during surgery. This results in reduced blood loss and reduced surgical pain. The final scar will be much less noticeable.

When first developed, hip replacements were generally cemented in. With improved technology, the use of uncemented prosthesis has superseded cemented replacements except in a few rare circumstances. Now the majority of hip replacements in the USA and Europe are uncemented.

Miss Muirhead-Allwood has been a dedicated advocate of the cementless technique for over 20 years and currently operates almost exclusively without cement in all primary and revision hip replacements.

In an uncemented hip replacement, the arthritic head of the femur (the ball) and the lining of the acetabulum (the socket) are removed. A femoral component is inserted into the healthy section of the patient's thighbone and a hemispherical socket is inserted into the pelvis. The surface of the artificial hip prostheses is textured and coated with a compound that stimulates the bone to grow onto its surface using the same mechanism that occurs when a broken bone heals itself, so the patient is essentially making their own glue.

Once the bone has grown into the prosthesis an extremely firm bond is made which virtually eliminates any loosening, a major cause of failure of hip replacement surgery.

A large variety of different prostheses are available from different manufacturers. Your surgeon will choose the one that best fits your anatomy, the strength of your bones and your level of activity.

The ball and socket of the new joint can be made from a variety of materials. All prostheses used by our surgeons use materials incorporating the latest developments. These offer much harder surfaces and reduce the possibility of wear, a major reason for needing revision surgery.

The London Hip Unit has also huge experience with custom made hips. These are tailor-made computer-designed prostheses that now are used only occasionally when a patient’s anatomy fails to fit any ready-made hips.

Further information can be found at:

The National Institute for Clinical Excellence gives guidelines on single mini-incision surgery. www.nice.org.uk

The National Joint Registry provides an annual report on performance of hip replacements. www.njrcentre.org.uk

The British Medical Journal provides patient information leaflets based on best practice. www.besttreatments.bmj.com

The Arthritis Research Campaign also has patient information leaflets on hip replacement and more information on arthritis. www.arc.uk

NHS Direct provides patient information on hip replacements. www.nhsdirect.nhs.uk

The London Hip Unit also offers patients hip resurfacing. Resurfacing is where the femoral head (the ball) is resurfaced rather than the entire head of the thigh bone being replaced.

Hip resurfacing in its current form has been performed since 1997. Initially hailed as a procedure which could supersede total hip replacement, it was widely practised. Problems have arisen if the bone is not sufficiently strong and with problems with metal on metal wear. The problems with metal wear have been exaggerated by poor prosthesis placement and some inferior designs such as the ASR prosthesis.

Fortunately, at The London Hip Unit, we use the Birmingham Hip Resurfacing and this prosthesis has been shown to have excellent results. We find that it can produce higher function in sportsmen and in the correct patient group produces a long-lasting solution with excellent function. Resurfacing is best suited to younger male patients less than 60 years old as they tend to have stronger bones and larger femoral heads. Unfortunately, hip resurfacing is generally not performed on women as statistically women have not done as well with resurfacings.

Because most of the bone of the femur is preserved it is relatively easy to convert to a total hip replacement if it fails in the long term. There is also less likelihood of dislocation and patients can continue with more vigorous sporting activities.

We are currently involved in investigational work using ceramic on ceramic hip resurfacing and this may be a promising future direction for hip resurfacing surgery.

The head of the femur (the ‘ball’) is shaped and covered with a metal cap, leaving the remaining bone underneath. This differs from total hip replacement where the entire head and the top section of the femur (thigh bone) are replaced. The socket is also lined with a metal cup. The patient's body will then produce synovial fluid to provide some fluid film- lubrication between the two metal surfaces.

Revision hip replacement surgery is also available at The London Hip Unit in addition to total hip replacement surgery and hip resurfacing.

Revision hip surgery is carried out when a failed artificial hip joint is replaced with a new one. Although total hip replacement and hip resurfacing surgery now last much longer than previously, most artificial joints can’t be expected to last forever. Hip replacements can wear out during an individual's lifetime, or become loose. In a small number of cases a hip replacement fails due to infection or a fracture.

In a revision hip replacement, one or both parts of the artificial hip joint (prosthesis) must be removed and a new prosthesis fitted. Revision hip surgery is often more complex and recovery can sometimes be slower and the scar larger than for first time hip replacements. Often the duration of these operations is longer and carry a higher complication rate.

Revision surgery that is needed because of an infection is usually carried out in two stages. The first stage involves removal of the infected prosthesis and insertion of an articulating antibiotic spacer for six to 12 weeks. The second stage is the insertion of a new prosthesis.

Revision surgery is considerably more complex than primary surgery and a higher level of experience and skill is required. Miss Muirhead-Allwood is internationally recognised as a pioneer in this field. Over her career she has been instrumental in developing successful systems and techniques for revision surgery and teaching them to her junior surgeons some of whom currently work in the LHU and she continues to research and lecture worldwide on this subject. The London Hip Unit is a tertiary referral centre for patient's requiring complex revision surgery and a lot of this surgery is now performed by Mr Angus Lewis.

It is extremely important to us at The London Hip Unit that you are fully informed about any forthcoming surgery. We would like you to take some time to read about the following risks of hip surgery and ask any questions you may have when you see us in clinic. Hip surgery is a major operation. Although complications are rare, they can still occur.

If you decided not to have a hip replacement at the present time your condition could be managed medically. This concentrates on controlling pain and improving function where possible. Drug treatment with pain killers including anti-inflammatory is often tried to control pain. Other things like losing weight, physiotherapy for muscle strengthening, range of movement exercises and using walking aides may be used to alleviate or control symptoms. However, over time the hip is likely to deteriorate, though no one can predict at what rate.

A hip replacement is generally considered when other non-surgical options can no longer restore function of relieve discomfort adequately and the pain and/or stiffness is affecting your work and daily activities.

As with all procedures, hip replacement surgery carries risks and complications.

The more common complications (2-5%) are:

• Bleeding - This is usually small and can be stopped in the operation. However, large amount of bleeding may need a blood transfusion or iron tablets. Rarely the bleeding may form a blood clot or large bruise within the wound (haematoma). If this becomes painful, further surgery to remove it may be required.
• Pain - the hip will be sore after the operation. If you are in pain it is important to tell staff so that medicines can be given at regular intervals. Pain will usually improve with time, but rarely pain will be a long term problem. This may be due to altered leg length, nerve damage, or various other complications. Sometimes there is no obvious reason.
• Prosthesis loosening/Wear - Modern operating techniques and new implants mean most hip replacements last over 15 years. In some cases, this is significantly less and the reason is often unknown but can be due to excessive wear of the cup liner or from overuse. Infection also causes loosening. If the loosening is significant a revision of the joint replacement will be needed.
• Leg Length - Occasionally surgery may result in a difference in leg lengths. Your body will generally compensate for small differences. A shoe raise can be used if the difference is large. Rarely a further operation may be required to correct the difference. At the hip unit we take pride in our results of avoiding leg length inequality by meticulous planning and the use of robots or navigation software where it is felt to be beneficial
• Joint Dislocation - If this occurs, the joint can usually be put back in place without the need for further surgery although a general anaesthetic is usually needed. Sometimes this is not possible and an operation is required or rarely if the hip keeps dislocating revision surgery may be necessary. You will receive instructions from your care team on activities and positions to avoid which may put you at risk of dislocation. A hip brace may be used to allow the soft tissues to heal following dislocation.
• Urinary problems - The anaesthetic can cause difficulty in passing urine. In this case a catheter (sterile tube) may be passed in to the bladder to drain the urine and will remain in place for a day or two. Urinary tract infections are effectively treated by a course of antibiotics.
• Constipation - This is a common complaint following surgery due to medications and immobility. It can be eased by drinking plenty of fluids, eating a well-balanced diet (including plenty of fruit, vegetables and fibre) and walking when able. If necessary it can be treated with laxatives and the nurses in hospital will be able to advise you.

Less common complications (1-2%):

•  Superficial Wound Infection - You will be given antibiotics during and after the operation and the procedure will be performed in sterile conditions with sterile equipment. Despite this, infection can occur in the wound. This can happen whilst in hospital or after you go home. The wound site can become red, hot and painful. There may also be a discharge of fluid or pus. All infections are treated by a course of suitable antibiotics although occasionally an operation may be necessary to washout the area.

Rare complications (<1%):

• Deep Vein Thrombosis (DVT) - This is when a blood clot occurs in the deep veins of the legs (usually). This may present as red, painful and swollen legs. The risks of a DVT are greater after any surgery (but especially bone surgery). It can be easily treated with blood thinning medication. However, if not detected a portion of the clot can sometimes break off and travel to the lungs causing a pulmonary embolism (less than 1%) - a potentially fatal condition (see below-rare complications). Several precautions are used to reduce the possibility of blood clot formation. These include the wearing of TED stockings and flowtron gaiters. These are devices that keep the blood moving in the legs and stop it pooling and forming clots. Flowtron gaiters are only used in hospital when not moving around. Blood thinning medication is also given from the day after surgery. It is since our patients have started taking Rivaroxaban that our incidence of DVT has dramatically reduced, therefore it is important that you remember to take the blood thinning medication that you were prescribed to go home on. It is also important that you continue your bed exercises while you are not moving around and early mobilisation plays a vital part in the prevention of a DVT.
• Serious infections - Rarely an infection can develop deep around the prosthesis. It may be treated by a course of suitable antibiotics or it may be necessary to washout the joint. If a major infection does not respond to antibiotics the hip implant will need to be removed and replaced at a later date or in extremely rare cases the hip may have to be left without a joint. Infrequently, the infection can lead to sepsis (blood infection) and stronger antibiotics are required.
• Altered wound healing - The wound may become red, thickened and painful (keloid scar). Massaging the scar with cream when it has healed can help.
• Nerve Damage - Efforts are made to prevent this. However, damage to nerves around the hip is a risk. This can cause temporary or permanent altered sensation along the leg. The sciatic nerve is at most risk when the posterolateral approach is used and it is identified and protected during surgery. The lateral cutaneous nerve of the thigh is most at risk in the direct anterior approach. Damage can lead to temporary or rarely permanent weakness or altered sensation in the leg.
• Fracture of the bones of the hip - Rarely a crack or fracture can occur in the bone of the hip. Often this can be fixed during the hip replacement surgery but a later operation may be required for fixation. A periprosthetic fracture can occur at any time in the postoperative period which may need treatment
• A heart attack, stroke or chest infection - Any big operation puts a strain on your heart, brain and chest. A very small number of people have serious problems soon afterwards such as a heart attack, stroke or a bad chest infection. These can occur if you already have heart disease or a bad chest. Therefore, if appropriate, the anaesthetist will liaise with your medical team to ensure you are in the best possible condition prior to surgery.
• Bowel obstruction - Mechanical obstruction of the small or large bowel can occasionally happen. This can often be managed medically by resting your bowel and having a nasogastric tube and fluids. If the obstruction persists, bowel surgery would be required.
• Pulmonary Embolism (PE) - A PE is a consequence of DVT. It is a blood clot that spreads to the lungs and can make breathing very difficult. A PE can be fatal.
• Death - This extremely rare complication can occur from  some of the above complications.