HIP REPLACEMENT

As described on the hip conditions and hip treatment pages, the intended benefits of surgery and to safely and effectively treat your pain and to restore you back to your normal level of function. 

Modern hip implants are made of robust and hard-wearing materials such as ceramic on highly cross-linked polyethylene. This means that will serve you well even under demanding loading conditions such as cycling, running and skiing. It is advised that caution is taken with activities that lead to repetitive forceful unloading (taking the weight off the foot and hip) and loading (putting the body weight forcefully down on the foot) of the hip as these may accelerate the wear of the hip bearing surface. If your preferred activities and sports involved long distance endurance running on hard surfaces (such as tarmac) or competitive mogul skiing, then we can discuss this and select the best option for you.

There are a number of things that will or can happen after your hip replacement that you need to know about before deciding whether surgery is the right thing for you. We will discuss these together when you are deciding whether to have a hip replacement and we will both sign a consent form to say that we have discussed these and that you have had the chance to ask any questions you may have. If we complete the consent form in clinic, we will confirm on the day of surgery that you are happy to proceed and have no further questions. The National Joint Registry has produced a patient decision support tool (https://jointcalc.shef.ac.uk) which you can use in order to predict what your individual risk and outcomes of undergoing hip replacement may be. One important caveat for that is that the tool is based on the outcomes of patients who chose to undergo surgery, so patients who may have been similar to you but chose not to have surgery are not represented. 

Risks:

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• Scar: you will have a scar over the side of your hip. The length of the scar will depend upon the thickness of the soft tissues and the complexity of your hip replacement. We will use an incision that is long enough to safely perform your operation but not one that is longer than necessary. The scar may remain tender until the wound and soft tissues are fully healed. If there are any problems with the wound healing (such as fluid discharge from the wound or redness around the wound), it is important that you contact my secretary, or if you are unable to speak to them, the hospital where you had your operation performed so we can review the wound and make sure everything is satisfactory or start any needed treatment.

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• Bleeding: The risk of injury to a major blood vessel requiring repair during a hip replacement is very small. Most of the bleeding that occurs is from smaller blood vessels and this will be stopped at the time that it occurs during an operation. It is unusual now to need a blood transfusion after a first-time total hip replacement, but your blood levels and symptoms will be checked before your operation and monitored afterwards. If your levels are low before your operation, we may recommend that you have iron supplements or come into hospital to receive an iron transfusion (iron given via a drip) to improve these. You may also need investigations performed to establish why they are low so that this can be treated. We will ensure such factors are optimised before surgery to reduce the risks for you. If the blood levels are a little low after the operation, you may need iron supplements. If they fall further or you develop symptoms related to low blood levels, you may need a blood transfusion. Very rarely, you may need a blood transfusion during your operation, this is more common in revision surgery but still rare. We would only do this if absolutely required. You may develop a haematoma (collection of blood) around the hip or under the skin. If this is large, it may require evacuation although this is rare.

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• Blood clot formation in the veins or lungs: Blood clots may form in the deep veins at any time but the risk of this happening increase with periods of immobility and when undergoing operations. Your risk will therefore be increased by undergoing hip replacement surgery. We will take steps to reduce the risk of this such as using pumps on your feet and calves during the operation and until you are mobilising, mobilising you as soon as is safe to do so after the operation, by using compression stockings in hospital if these are safe for you (the current national guidance is that these do not need to be continued after you go home), keeping you well hydrated and giving you medication to make blood clots less likely. Medication options include injections of heparin in hospital followed by aspiring after this, tablets such as rivaroxaban or continuing your own medication if you are already on a drug to reduce the risk of clot formation. If a clot does form in the deep veins of the leg, it may go to the lungs and be a serious threat to your health.

• Infection: Infection can be a serious complication after joint replacement. Sometimes an infection may only be superficial and relatively simple to treat, requiring antibiotics alone. If the infection is deep and affects the tissues around the joint replacement itself, attempts to treat and cure the infection will involve further surgery. If we catch the infection early, we may be able to treat the infection by removing the infected tissue and replacing the exchangeable parts (such as the head and liner). If the infection is established or has been partially treated for a period of time, surgery usually involves the removal and replacement of all of the implants, a much bigger operation that may need to be done in multiple stages. This is why it is important that you let us know if you have problems with the wound or anyone suggests prescribing antibiotics for infection around the hip. The risk of undergoing revision for deep infection after first time surgery is between 0.4 and 0.7%. It can be higher if you are diabetic, have a high body mass index or other risk factors we will discuss. Following revision surgery, the risk of infection is higher at around 1.6% overall.

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• Pain: You will have some pain after the operation. Our aim is to keep this to a minimum and certainly to keep it under enough control so that you can mobilise and perform your exercises. It is generally easier to take regular pain relief to try to keep out of pain than it is to get you out of pain so I do recommend taking regular basic pain relief (such as paracetamol, anti-inflammatories and/or codeine) for at least the first couple of weeks after the operation. When you first wake up from the operation, the hip will usually be comfortable as the anaesthetic and local anaesthetic we inject into the wound are still working. If you begin to feel pain and this is increasing, please let the nursing staff know so that your pain relief can be reviewed.

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• Long-term pain: Around one in ten patients report that they get persistent pain in the longer term after hip replacement. Some of these patients still feel that it was worth having the operation done as the pain is better than it was or because their symptoms have improved in other ways however this is not always the case. Some patients do tell us that they would not have had the operation done if they had known what the result was going to be like. This is why it is critical that we fully explore the nature of your pain and why you are getting it, as well as other potential sources and how much they are contributing to make the risk of this as low as we can.

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• Dislocation: When we perform your total hip replacement, the head of the implant is smaller than the head it replaces, this is because we also have to fit the cup in. This and the fact that the head and the cup are not attached means that the head can come out of its socket. The risk of this is approximately 2% over the life of the hip replacement. You will be asked to avoid particular positions that increase the risk of this (such as bending you hip up and turning your knee in to get to your foot) and it is important to remove as many trip hazards as you can from your house prior to undergoing surgery as if you fall over before the muscles are healed, the hip may come out of joint. If this does happen, you will need to be seen by a doctor, usually in hospital to have the hip put back in. If this goes on to happen multiple times, revision surgery to stop it happening may be required.

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• Leg length discrepancy: Nearly all peoples legs are slightly different lengths. If you develop osteoarthritis, it is likely that you will loose length in the affected as the cartilage and bone is worn away. Part of the aim of the operation is to restore your leg lengths, this is achieved by comparing to the other side and checking various landmarks and the soft tissue balance of the hip. It may be necessary to alter your leg length in order to achieve a stable and balanced hip or because you have an issue such as curved spine which can create an apparent difference in the leg lengths. If you have a preference in terms of leg lengths, it is important to tell me about this so we can factor this into the decision-making process. Small differences are generally not noticed but sometimes the difference can be enough that it is noticeable.

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• Stiffness: Your hip may become stiff after a hip replacement although this is rare. Generally, those at greatest risk are those with a very stiff hip prior to the operation. Hip replacement generally improves range of motion, but this is not guaranteed. Very rarely, patients form bone in the soft tissues and muscles (heterotopic ossification) after surgery or injury and this can occur after hip replacement. If this has happened to you before, there may be steps we need to undertake to reduce the risk. If it does happen to you and it makes the hip very stiff, an operation to excise the bone may be required.

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• Numbness: Nearly all patients will experience some numbness after a total hip replacement. This will be felt along the scar itself. Initially there may be a patch of numbness around the scar, but this improves over the first few months after the operation and generally fully resolves. There can be numbness caused by bruising to, swelling around, or damage to one of the large nerves that travels past the hip as described below.

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• Nerve injury: There are large nerves that travel past the hip that are close to where the operation takes place. These include the sciatic, femoral and obturator nerves. If there is an injury to a major nerve, it can cause numbness further down the leg or weakness of muscles (e.g. the muscles that pull up your ankle in the case of the sciatic nerve or the muscles in the front of the thigh in the case of the femoral nerve). If there is bruising or swelling, this normally resolves within a few months of surgery, but you may need to wear a splint for your ankle to stop you tripping. The chances of nerve injury are less than 1% but are increased by factors such as having had previous hip surgery, scarring and severe deformity. Direct injury to the nerve is very rare, if this does occur, surgical exploration or operations to repair the nerve or transplant tendons may be required. 

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• Fracture: When your bones are being prepared during the operation or implants inserted, there is a risk of fracture of the bones. The type of operation that is performed for you will take account of these risks and implants that minimise this risk for you will be selected. If a fracture like this does occur during your operation, it will either be fixed, or we will switch to other implants to bypass the fracture. The aim will be to perform an operation that allows you to fully weightbear straight away. Fractures around hip replacements can also occur in the years after surgery, typically if you have a fall or other form of trauma. If this does occur, revision surgery may be required to address this. The risk of a fracture occurring is less than 1%.

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• Adverse reaction to debris: All types of joint replacements will produce debris of one kind or another. This can either due to wear of the bearing surfaces themselves or due to corrosion or wear from modular junctions where implants are fixed together. Some of the materials released can cause problems such as soft tissue destruction and may have effects on remote organs, such as was the case with metal debris released from metal on metal hip replacements. If soft tissue damage is severe, this can lead to late problems with dislocation. Reaction to debris can also need to the lead for revision. With the kind of implants that I use, the risks of this are very low.

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• Wear and loosening: As time goes on, bearing materials will wear and implants that are fixed to bone may become loose. These are the most common reasons for revision of hip replacements in the long term. Over 95% of all total hip replacements will last for 10 years or more and 58% of those last for 25 years or more. When we limit that to contemporary total hip replacements using bearings such as ceramic on highly crosslinked polyethylene, over 93% will last for 20 years or more and it is predicted that over 92% will last for 30 years or more.