Hip Replacement Complications
Hip replacement is an astonishingly successful operation. However, surgery does not always proceed as planned. Complications do occur, and everyone about to have hip replacement surgery should be aware of their existence.
It is important to keep a realistic attitude to these problems as complications of total hip replacement are infrequent and most are reversible. Hip replacement risks are usually of a reasonable level compared to the difficulties of managing with a very painful and arthritic hip.
Many people can look at hip replacement cost comparisons and see that hip replacement costs are much lower for a hip replacement abroad, however the level of complications can be higher and the matter of continuing follow up and management of these problems is an issue which needs settling before engaging on a foreign trip to have surgery on the hip joint
More information can be read about complications at The Hip and Knee Institute and NHS Choices Hip replacement risks page.
Age is important as the older the person the higher the risk that complications will occur. For people over 80 years old, for example, 20% are likely to experience at least one complication after hip replacement. Complications can be divided into three groups:
- Those which occur during the operation
- Those occurring in the few weeks after the operation
- Long-term (six months or more after surgery)
Complications during operation
- Nerve damage (risk: 0.5-3.5%)
The sciatic nerve passes close behind the capsule of the hip joint and is theoretically vulnerable to direct damage from surgical instruments and indirect damage from stretching as the hip area is manipulated during operation.If this occurs there may be loss of muscle power and feeling in various areas of the leg. This should not be confused with the normal loss of feeling and power which may occur if an epidural anaesthetic is used to control pain after the operation. Provided the nerve has not been cut then it is unlikely that there is a surgical solution to the problem and treatment will be ‘expectant’ - the problem will be carefully documented and monitored over time. If there is nerve damage, the results depend wholly on how bad the damage is and how widespread in the nerve.The outcome may vary from a normal recovery to no change from the initial state. If there is a long-term problem, in some cases an abnormal pain state can develop in areas of the leg.
- Vascular damage (risk: 0.1% for primary replacements and less than 1% for revision replacements).This risk involved direct trauma to blood vessels that run close to the area of operation and are usually dealt with during operation.
- Fracture (risk: less than 1% for primary replacements and 3% for revision replacements).
Due to the force involved in some of the operative procedures, fractures are a possibility. These are most common in the femoral shaft and dealt with again during surgery. As above this may delay the post-operative rehabilitation.
- Cortical perforation (risk: up to 4.5%).
During the operation there is a possibility of the surgeon breaking through the outer hard layers of bone during preparation of the areas. This could lead to a hole in the socket leading into the abdomen or a hole in the side of femoral shaft.These problems are dealt with in surgery and may alter post-operative instructions - for example the person may be asked to reduce the amount of weight borne through the new joint until some bone healing has occurred.
- Leg length inequality (risk: 6% for primary replacements and 7.5% for revision replacements).
People are often surprised when they get up after hip replacement to feel the difference the operation has made to the length of their leg, or at least to how long it feels. In many cases this ‘problem’ goes away as the pelvis adjusts to the change and the legs then feel the same length. In some cases there is a true lengthening of the operative side. Shortening does not normally occur - if the leg is significantly shortened after operation the joint may well have dislocated. The surgeon can make adjustments during the operation to minimise the lengthening produced but there are restrictions on where the components can be placed and this limits room for manoeuvre. In some cases the extra length is inevitable and may have to compensated for by a shoe raise on the other side
Complications After Surgery
- Dislocation (risk: 0.5-3%).
The normal hip is a deep and stable joint with very strong ligaments so it takes a great deal of force to dislocate it. The artificial joint is different in many ways and is much easier to dislocate. The new joint is shallower, the capsule surrounding the hip has been cut away and the muscles will probably be weak from pain and disuse. However, dislocation is not a disaster, just a complication to be dealt with.
- Infection (risk: 7% for superficial infections and 0.5% for deep infections).
Infection is perhaps the most serious risk to the life of a joint replacement. In the case of deep infections into the joint and the surrounding tissues, the joint often has to be removed before the infection will settle with treatment. A new joint may then be implanted when the risk of infection has reduced to normal levels.An infection may be introduced at the time of the operation or be acquired later on. Other infections the person may develop, such as in the bladder or chest, must be strictly controlled to prevent the possibility of spread through the blood to the new joint.
- Trochanteric problems (risk: 9.5% for trochanteric non-union and 17% for trochanteric bursitis).
The greater trochanter is a large area of bone on the femur below and to the outside of the ball of the hip joint. It can be felt as a bony lump at the sides of the tops of the thighs. The trochanter is the area of the thigh bone where many of the large hip muscles attach, so is vital to normal function of the hip area.When a lateral approach has been performed in the operation, the trochanter is detached to gain access to the hip joint and reattached after. In some cases the trochanter does not heal back in place on the thigh bone but remains as a separate piece. This can cause pain, weakness and loss of hip function.
- Bowel complications (risk: 1%)
- Urinary complications (risk: up to 35%).Most people who have hip replacement are elderly and many already have urinary difficulties. The operation and the anaesthetic can disturb these functions, aided by the reduced mobility for recovery period. Retention, the inability to pass urine, is common more in males.A catheter may be inserted to allow the person to empty their bladder. Catheters are associated with a higher risk of infection so are removed as soon as practical. A watch is kept to see that the person does not develop a urinary infection as this poses a risk to the new joint.
- Cardiovascular complications, including deep vein thrombosis (risk: up to 56%).A hip replacement is a large surgically-performed injury to the body, and it responds as to a normal injury. This involves, alongside many other changes, alterations to the blood-clotting mechanisms. Add this to the immobility of the person after operation and the reasons for cardiovascular complications become clear.Deep vein thrombosis may occur when a clot forms in the deep veins of the calf or thigh and these clots are apparently very common in the calf. The risk is that a part of the clot may break off and enter the circulation, ending up in the small blood vessels of the lung as a pulmonary embolus.This can be life-threatening and is usually treated immediately with blood-thinning drugs such as heparin. Once the blood is thin enough the long-term drug, usually warfarin, is introduced to control clotting for the length of time required.
- Respiratory complications (risk: 1%).The immobility after the operation and the anaesthetic can result in respiratory complications, especially if the person had chest problems before operation. A chest infection needs treatment to prevent risk to the new joint.People with chest problems may have a spinal rather than general anaesthetic to prevent the likelihood of chest infection.
- Haematoma formation (risk: 3%).The main areas of bleeding are controlled during operation by cauterising bleeding vessels but there is some oozing of blood from the cut tissues. This is the reason for the insertion of a drain for 24-48 hours, to drain away any collection of blood and swelling fluid. Sometimes the procedure does not work out as planned and a collection of blood and fluid forms in the hip area. If it is large the person may be taken back to the operating theatre to have the haematoma drained. Haematomas can cause pressure, pain and delayed healing and may become infected, so management of them is important.
- Wound dehiscence.Remarkably, the large wounds produced during joint replacement surgery heal very well. However in some cases the wound can split open and show little sign of healing. This may be due to superficial infection of the tissues forming the sides of the wound.
- Swollen ankles.Some people may develop this problem, which results from a lowered efficiency in the cardiovascular system. The fluid which comes out of the blood vessels in the legs is not returned well back to the heart and remains in the tissues of the furthest parts of the body. In some cases this problem may be attributed to a degree of heart failure.
- Skin complications (risk: less than 1%).It is not normal for the body to remain in one position for very long - we are moving about all the time, even when we are asleep. This helps prevent undue pressure on any particular area of the body which might cause damage to the tissues. An elderly person may have fragile skin to start with, so spending a long period in one position exposes them to the risk of pressure sores. Nursing care is very important in preventing this risk.
- Metabolic complications (risk: less than 1%).
- Aseptic loosening. Joint replacements eventually fail if enough time is allowed to elapse. Aseptic loosening is the commonest reason for failure and the necessity of revision - loosening of the components in the absence of infection.This problem may be caused by several mechanisms - types of implant chosen, surgical technique, the amount of force applied to the joint by the user and time.
- Bone stock loss.The insertion of a joint replacement profoundly changes the forces that are transmitted through the hip. Bone relies on force being put through it to remain healthy and of normal size. When a hip replacement is inserted there can be areas of bone which experience greater forces than normal, and other areas which experience lesser forces, so called ‘stress shielding’. If areas of bone are shielded from the normal stresses the bone resorbs in those areas and becomes weaker. This can lead to migration of the components or in the worst cases, fracture.
- Late dislocation (risk: 2%)
- Late infection (risk: less than 1%)
- Bone fracture (risk: less than 1%)
- Ectopic ossification (7% for primary replacements and 15% for revision replacements).It is important that the body responds to the trauma of hip replacement by producing new bone at the bone-cement interface. However, in some cases new bone is laid down in the tissues where it should not be, causing pain and stiffness of the joint. Drug treatment may be given to minimise this risk.
If you plan to undergo hip replacement surgery this is a long list. However, it is important to recognise the reality of the situation so you understand what is going on should you experience a complication. You might also consider if your arthritic hip is troublesome enough to undergo this operation with all its risks. This list is not comprehensive, as there may be rare complications not mentioned here.