Total Hip Replacement

What is a total hip replacement?

A hip replacement involves replacing the damaged hip joint with either plastic, metal or ceramic components.

Your hip is a ball and socket joint. The ball at the top of your thigh bone (femur) is removed and replaced with either a ceramic or metal ball. The socket of your pelvis (acetabulum) is relined using either ceramic, plastic or metal.

Over the three years (1 January 2018 to 31 December 2020), 250,278 total hip replacements were undertaken.

When is a hip replacement necessary?

Most people with arthritis of the hip do not initially require an operation. A hip replacement is performed when your damaged hip is causing significant problems with your quality of life – usually pain and restriction of movement.

The lining of the ends of the bones (articular cartilage) allows them to glide smoothly over each other like ice on ice. If the surface lining is damaged, the bones move like concrete-on-concrete causing pain, stiffness, locking, reduced range of movement and giving way.

Hip replacement surgery is usually performed for arthritis. There are different types of arthritis, but in each one the smooth lining is damaged.

Arthritis can be caused by a number of different factors including age, obesity, injury, joint abnormality and hereditary factors.

A review by the National Institute of Clinical Excellence (NICE). Osteoarthritis: Care and Management, describes the best way to manage a person’s arthritis.

This can be accessed using the following hyperlink:

https://www.nice.org.uk/guidance/ng226

In summary:

• Self help – Weight reduction, patient education, walking aids, exercise, shock absorbing shoes, physiotherapy.
• Medication – Simple painkillers (paracetamol), stronger painkillers (co-codamol), topical painkilling creams, anti-inflammatory tablets (if allowed).
• Intra articular (into the joint) injections – Steroid and Visco supplementation injections.
• Complementary treatments – Glucosamine and chondroitin sulphate tablets. Acupuncture.

Surgery should be considered when you have tried all these and continue to experience symptoms that affect your quality of life. Although a hip replacement should significantly improve your quality of life, it will never be as good as your original hip.

Hip replacement surgery may also be needed for fractures of the hip, including those resulting from osteoporosis. Usually only the end of the thigh bone is replaced – a hemiarthroplasty.

There are no upper or lower age limits for having hip surgery, but the earlier you have surgery the greater the chances that you will eventually need the operation to be repeated (revised).

How is arthritis diagnosed?

All medical diagnoses should be made by taking a history, examining the patient and then undertaking appropriate investigations (usually an x-ray).

Patients usually complain of night, rest and start up pain (pain getting up from a chair). The pain is usually felt in the groin (where the hip joint is located). The pain may cause them to walk with a limp and prevent them from walking very far. 

Difficulty getting down to attend to feet or tying up their shoelaces is common.

Radiographs (x-rays) show a reduction in the height of the joint space due to the loss of the smooth joint lining.

What is the design of a hip replacement?

There are more than 60 different makes of hip replacement used in the UK. Most have a stem with a ball on top and a cup with a liner. 

The earliest recorded attempts at hip replacements were carried out in 1891 in Germany using ivory to replace the femoral head. The first metallic hip joint replacement was a hemiarthroplasty performed in 1940. 

Modern hip replacement surgery was pioneered by Sir John Charnley in 1962. His design consisted of a one-piece stainless-steel stem and head with a polyethylene (originally Teflon) cup. Both components were fixed using PMMA (acrylic) bone cement. Initial hip designs were made up of a one-piece femoral component and a one-piece acetabular component. 

Current designs have a femoral stem and separate head piece. Using an independent head allows the surgeon to adjust leg length and to select different materials for the ball. One piece plastic sockets are still used but most modern acetabular (cup) components are usually made of two pieces. There is a metal shell with an outer coating to encourage bone attachment and a separate liner. The liner is usually made of plastic or ceramic. 

The microscopic wear debris caused by the metal head moving against the plastic liner can cause loosening of the components. To combat this, hip manufacturers have developed different materials for the liners and heads. Typical pairing of materials includes metal on polyethylene (MOP), metal on crosslinked polyethylene (MOXP), ceramic on ceramic (COC), ceramic on crosslinked polyethylene (COXP) and metal on metal (MOM). Each combination has different advantages and disadvantages. Common sizes of femoral heads are 28 mm, 32 mm and 36 mm. While a 22.25 mm head was initially used, larger sizes are now available (38–54mm+) which allow increased stability and range of motion whilst lowering the risk of dislocation. 

Many artificial joint components are fixed into the bone with acrylic cement. However, increasingly and especially in more active patients, one part (usually the socket) or both parts may be inserted without cement. If cement is not used, the surfaces of the implants are roughened or have a specially coating to encourage bone to grow onto them. 

• Standard hip replacement – The damaged femoral head (ball) is cut off and a stem placed down the cavity in the thigh bone (femur). A ball is placed on this. The socket is replaced with a metal shell into which is placed a liner made of plastic or ceramic. 

• Hip resurfacing – Hip Resurfacing is an alternative to hip replacement surgery. It is a bone conserving procedure that places a metal cap on the femoral head instead of cutting it off. A solid metal cup is used in the acetabulum. Problems have occurred because of the bodies reaction to the metal ions released from several of these devices. Because of this, I no longer perform hip resurfacings. 
• Hemiarthroplasty – Hemiarthroplasty is a surgical procedure which replaces only the femoral head with a metal ball and leaves the acetabulum (socket) in its natural state. This type of replacement is usually performed after a hip fracture. With the passage of time the metal ball tends to erode through the acetabulum, or the replacement loosens. This operation is not performed for arthritis of the joint. 

What different surgical techniques are used?

There are several different ways of performing a hip replacement usually defined by the relationship of the surgical approach to the muscles of the hip.

Posterior (Moore), lateral (Hardinge or Liverpool), antero-lateral (Watson-Jones) and anterior (Smith-Petersen) are the more commonly performed.

New techniques are often variations of old techniques. Many do not have long term follow up.

Even when using “old techniques” most patients leave hospital 1/2 days after their surgery. It is the long-term survival of the implant that is important.

What is done in preparation for a total hip replacement?

It is important that you understand what is involved in a THR and that you are both physically and mentally prepared. 

Prior to listing you for surgery, I will discuss the potential benefits and complications in clinic. These will be included in the clinic letter I send you.

It is usual to be seen in a pre-operative assessment clinic. Bloods will be taken, a heart tracing performed, a water sample will be checked for infection and a swab taken to make sure you do not have MRSA. Swabs for Covid will be arranged. Any pre-existing medical problems such as diabetes and high blood pressure should be optimized before the operation. Patients who are on anticoagulants (blood thinners) will probably need to stop these before the operation. Please inform me of any medication you take when we first meet. Bring them with you when you come to pre-operative assessment and when you come into hospital. 

You will be asked if you are willing for the details of your operation to be entered into the National Joint Registry (NJR) database. The NJR collects data on hip and knee replacements to monitor the performance of joint implants throughout the UK.

Any sign of infection in the body (including colds) usually requires the operation to be postponed.

I will explain the operation to you when we first decide to proceed. On the morning of the operation, we will discuss the procedure again and we will complete a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and that you have given your permission for it to go ahead. It is important that you understand what is involved.

The fitter you and your hip are prior to surgery, the better. As part of your conservative (non-surgical) treatment you may have had physiotherapy to improve the muscle strength and range of movement. You will be using crutches or sticks immediately following your hip replacement, it easier to learn how to use them before the operation.

Bring loose fitting clothing with you to hospital as they are easier to get on and off after the operation.

How is a hip replacement performed?

It is a large operation performed using either a general or spinal anaesthetic. 

Spinal or epidural anaesthetics are used to numb the body from the waist down allowing you to remain awake throughout the operation. You will be required to fast prior to the operation. These instructions will be given to you before coming to hospital. 

In theatre, the hip is painted in an antiseptic solution to reduce the risk of infection. You are turned on your side on the operating table and special clamps are used to hold you securely in place. 

An incision (cut) is made over the side of the hip. The muscles are separated or cut to allow access to the joint. The hip is dislocated, and the worn-out ball cut off. The rough inside of the socket is smoothed using special reamers to allow the metal cup to be put in place. The liner is placed inside the metal cup. Special rasps are used to create room for the metal stem to be placed inside the thigh bone and securely fixed in place. Different head sizes and lengths are trialled to ensure that the leg lengths are equal, and the hip is stable. 

Operating theatres can be surprisingly noisy. If you have a spinal anaesthetic, you may hear the sound of the drill and saw and feel the impact as the implants are hammered into place. You will hear the sound of the anaesthetic machine and feel the blood pressure cuff on your arm as it measures your blood pressure. I have music playing in theatre or you can choose to bring in music of your own choice. 

What happens after the operation?

You will be transferred to a bed in the operating theatre and taken out to the recovery room where you will begin to wake up from the anaesthetic. 

Once the recovery nurse is satisfied you are sufficiently awake, you will be taken back to the ward. You will have a drip in your arm and may have a catheter (a tube into your bladder). The anaesthetist may give you a special pump that gives pain killer medication – patient controlled analgesia (PCA). This allows you to control the amount of pain killer you are receiving by pressing a control button. It is easier to suppress pain than to treat pain. Use and ask for pain killers a soon as you feel any discomfort. 

You will be closely monitored on the ward with the nurse regularly observing your temperature, pulse and blood pressure. 

The day after the operation the drip will be removed as soon as you are eating and drinking. Your haemoglobin (red blood count) will be checked.  An x-ray will be taken. The physiotherapist and nurses will help you out of bed and begin your rehabilitation exercises. 

It is common to become constipated due to the pain killing drugs and relative inactivity. Medication will be given to “help you on your way”. 

You will receive a blood thinning injection (into your tummy or leg) every day. When you go home you will be given blood thinning tablets to take for approximately 20 days. Check with your insurance company if they will pay for them, or if your GP will prescribe them otherwise you may be charged. You will be asked to wear compression stockings to help prevent blood clots forming. 

It is usual to be in hospital no more than 1 night. Patients are discharged when the wound is clean and dry, your bowels are open, you only require pain killers by mouth and the physiotherapists are happy. You will normally be using sticks and will be competent in using the stairs. The physiotherapist will give you a home exercise program (HEP). 

I will see you approximately 10-14 days following your operation and then at 6 weeks after to monitor your progress. 

What are the possible side effects and complications of surgery?

Total hip replacement surgery is a very common operation and is very safe. Most hip joint operations are problem free but serious complications can arise in 2% of cases. Most complications are minor and can be successfully treated. 

Side effects are unpleasant effects of drug or medical treatments, that happen in addition to the intended outcome. A complication is an additional problem that occurs which makes it more difficult to treat the original problem. 

To make an informed decision and give your consent, you need to be aware of the possible side-effects and possible complications of this procedure. Despite all the potential side effects and complications listed below, 90% of patients are happy with their new hip. 

A Patient Decision Support Tool (PDST) has been developed using National Joint Registry (NJR) data to enable patients to estimate the risks involved. I would recommend trying it: 

https://jointcalc.shef.ac.uk/

Side-effects

You usually expect some pain, stiffness, swelling and bruising around the hip. This is likely to last for some weeks and will gradually improve as the hip heals and you get back to your normal day-to-day activities. 

Initially there will be some numbness around the scar. This normally returns to normal. 

Complications 

These can be divided into those related to any operation and those related to the operation itself. 

Possible complications of any operation: 

• Reaction to anaesthetic. 
• Haematomas/bleeding.
• Blood clots. 

These can form in the legs and travel to the lungs (pulmonary embolus 0.3%) which can be fatal. If they stay in the legs (deep vein thrombosis 2-3%) you will need to be treated with blood thinners for about 3-6months. 

Possible complications of the hip replacement operation 

• Dislocation – The term ‘dislocation’ means the slippage of the ball out of the socket. Whilst there is always a chance of the hip dislocating it is highest in the first 6 weeks after the operation. The risk of dislocation is approximately 5%. To reduce the risk of this complication, patients’ are advised not to bend their hip more than a right angle (90 degrees) for six weeks following the operation. This may occur for example, if you were to sit in a low chair or bend to the floor or reach for their toes. Also, crossing the legs or twisting the hip could cause a dislocation and should be avoided. 
• Infection in the joint – On average this happens in about 1 in 50 cases. Usually, the infection can be treated with antibiotics. About 1 in 150 patients develop a deep infection which may mean removing the new joint until the infection clears up. In extreme cases, where the infection cannot be cured, the hip replacement must be removed permanently. 
• Change in the length of the leg – Some increase in the length of the leg on the side of the hip replacement can occur after the surgery. Usually, the increase is small and is not noticeable. Sometimes the leg seems long immediately after surgery when in fact both are equal length. An arthritic hip can develop contractures that make the leg behave as if it were short. When this is removed with replacement surgery, the body can feel that the leg is longer. This usually resolves within a month or two. If the legs are truly unequal, a small raise in the shoe on the unoperated side can be used. 
• Wear and loosening – The most common problem with an artificial hip is that it does not last for ever. With time the components may loosen form the bone. It is uncommon for loosening to occur in the first 10 years from the time of surgery. Advances in technology and technique hope to improve this figure, but only time will tell. Every moving surface creates wear, the hip is no different. The younger you are when the hip is put in and the more active you are, the quicker it will wear. Manufactures are continually trying to improve the bearing surfaces (plastic, ceramic).The likelihood of needing another operation is increased if you are overweight or involved in heavy manual work. It is possible to redo (revise) the replacement, but each time the result is not quite as good or lasts as long. It is hoped that 90% of hips will still be working well 10-15 years after they are put in. 1 in 40 in the first 5 years. 
• Continued symptoms – Although some people are disappointed with the outcome of their surgery, or are unsure whether there has been an improvement, about 90% of people who have had the operation say they are happy with their new hip. 
• Nerve damage – Rarely, the main nerve of the leg, the sciatic nerve, can be injured. The risk of such an injury is about 1 in 100. Feeling in the calf or shin area may be affected and movements of the foot and ankle may be reduced or absent. Pain may be present from the hip into the foot. 
• Bone fracture – 1 in 50. The bone around the artificial hip joint can sometimes break after a minor fall – usually after some months or years especially in people with weak bone (osteoporosis). If this occurs surgery is usually needed to fix the fracture and/or replace the joint components. If this occurs at the time of surgery a special wire is placed around the bone. 
• Ceramic complications – Ceramic is a similar substance to china and can break. This occurs in about 2% of the time. Ceramic bearings may also cause an audible, high pitched squeaking noise with activity. 
• Metal ion release and debris – These have been common with some resurfacing replacements. The metal ion particles can cause damage to the bone and soft tissues around the replacement. These problems are more common in women. The cause is unknown and is probably multifactorial. This can happen with small metal heads but is more commonly seen when large metal heads are used. Some designs have performed particularly badly. 

How do I look after my new hip?

The physiotherapist or an occupational therapist will tell you the ‘dos and donts’ after hip surgery – how to get in and out of a bed, a chair, the shower etc. It’s very important to follow this advice. 

You should not bend the hips to more than 90º (e.g. squatting, or sitting in a low chair or couch) in the first 6 weeks. There is always a risk of dislocation, but it reduces after the first 6 weeks. 

Following discharge from hospital you need to pay attention to the following potential problems. 

• Wound care – Keep the wound area clean and dry. A dressing will be applied in the hospital and should be changed as necessary. Ask for instructions on how to change the dressing before you leave the hospital. You may be allowed to shower but not bathe until the sutures or staples are removed, usually 10-14 days after surgery. Please let me know if the wound appears red or begins to leak.
• Blood clots – Calf pain, chest pain, or shortness of breath are signs of a possible blood clot. Notify me immediately if you notice any of these symptoms. Keep using your compression stockings (although their use is being reviewed) and taking the blood thinning tablets you have been given until they are finished.
• Stiffness – The hip can become very stiff in the weeks after the operation for no obvious reason. You will have been shown exercises by the physiotherapist whilst in hospital and it is usual to have some physiotherapy once you leave hospital.
• Pain – Pain should reduce after about four weeks although some pain is likely for as long as six months. Make sure you take regular pain killers and anti-inflammatories (if allowed). Use them before the pain builds up.
• Swelling – raising the foot off the floor (on a footstool or similar) is a good way of reducing swelling. Get up and walk around for at least five minutes every hour so as not to increase the risk of a blood clot.
• Infection – If you notice any infection or sore on your leg, you should seek early advice from me or your GP. You should also look after your feet to reduce the risk of infection. 

Getting back to normal

You may need some help at home for several weeks. If you do not have sufficient help at home, you may wish to spend some time in a rehabilitation centre. 

The following tips can make the initial period more comfortable: 

• Rearrange furniture so you can manoeuvre with a stick or crutches. You may temporarily change rooms (make the living room your bedroom, for example) to avoid using the stairs.
• Remove any rugs that could cause you to slip. Securely fasten electrical cords around the perimeter of the room.
• Use assistive devices such as a long-handled shoehorn, a long-handled sponge, and a grabbing tool or reacher to avoid bending too far over. 

It will be some weeks before you recover from your operation and start to feel the benefits of your new hip joint. Make sure you have no major commitments for the first six weeks after the operation. 

Keeping up your exercises will make a big difference to your recovery time. You’ll probably need painkillers as the exercise can be painful at first. Gradually you will be able to build up the exercises to strengthen your muscles so that you can move more easily. 

It’s important to use crutches during the first few weeks after surgery until the hip muscles are strong enough to support you. “It is better to walk well with crutches, than badly without.” Falling could damage your new joint. Your physiotherapist should advise you on these tasks but here are a few tips:

• Walking – Don’t twist your hip as you turn around. Take several small steps instead. It should be possible to walk outside about three weeks after your hip surgery but make sure you wear good supportive outdoor shoes. After three weeks, try to take longer strides to regain full straightening (extension) of the leg.
• Walking aids – Crutches and sticks are useful at first. As your leg gets stronger you will begin to walk without aids. 
• Going up and down stairs – When going upstairs lead with your unoperated leg, then move your operated leg up. When going downstairs, put your operated leg down first, followed by your unoperated leg. “Good leg to heaven, bad leg to hell”.
• Sitting – Don’t sit with your legs crossed for the first six weeks.
• Sleeping – You should sleep on your back for the first 6 weeks following surgery to reduce the risk of dislocation.
• Household jobs – You should be able to manage very light household tasks, but avoid heavier jobs, or get help with them, for the first few months. Avoid standing for long periods as this could lead to your ankles swelling.
• Driving – Getting in and out of a car can be difficult – you’ll need to sit sideways on the seat first and then swing both your legs around together. You can drive again when you are safe to do so. It depends on which leg has been operated on and if your car is a manual or automatic.
• Travel– Your new hip will activate metal detectors at airports. If this happens, you can show them your scar and they will usually pass a hand scanner over the area. You should not fly for more than 3 hours within 6 weeks following your operation. If you are travelling by car, get out regularly to stretch your legs. 

What activity, exercise and sport can I do after the operation?

Once home, you should continue to stay active. The key is not to overdo it! You can expect some good days and some bad days. 

Sensible exercise is critical for the long-term care of your hip. 

Some pain with activity and at night is common for several weeks after surgery. Your activity program should include: 

• A graduated walking program to slowly increase your mobility, initially in your home and later outside.
• Resuming other normal household activities, such as sitting and standing and climbing stairs.
• The physiotherapist will give you a set of exercises to undertake when you are at home to restore movement and strengthen your hip. It is usual to have ongoing physiotherapy as an outpatient, for some time following your operation.

As time goes on you should be able to return to normal exercise. The time that this will take depends on your level of fitness and activity prior to your operation. Cycling is an excellent aerobic workout, swimming (not breaststroke),  walking, hiking, and low-resistance weight lifting all are excellent ways to maintain fitness without overstressing the implant. 

Suitable activities include bowling, croquet, golf, doubles tennis, table tennis, ballroom dancing and square dancing. 

Your new hip will continue to improve for as much as a years after your operation as the scar tissue heals, the range of movement improves and the muscle strength increases. 

Resumption of sexual activity depends on several factors and the following information sheet is a useful guide. 

https://hipknee.aahks.org/a-guide-to-returning-to-sexual-activity-following-total-hip-and-knee-replacement/

Frequently Asked Questions

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