Implant loosening is the most common cause for repeated hip surgery. Hip replacements have been carried out in the UK regularly since the 1960’s and this, in combination with the increasing lifespan of the average person, means that there is an increasing need for revisions. Patients often present with dull pain in either their groin or thigh, depending on which part of the components are loose.

All patients are examined and the appropriate investigations carried out to check for infection etc as this can be a common cause. During surgery the hip is exposed and scar tissue removed. If there is evidence of implant loosening, the old implants are taken out and the bone surfaces are prepared. Some patients will require bone grafting and this is done using donated bone from other patients who have undergone hip replacements. Once that is carried out, the new implants are inserted and the hip is checked for stability and leg length. At this point it is still possible to make the necessary adjustments to ensure the best possible result. During the operation, multiple samples are taken to check for infection. While these are being processed, the patient will remain on antibiotics for between 5 and 7 days.

The patient will begin to mobilise the next day. If bone graft has been used, then they will not be able to fully weight-bear for 3 months, until the bone has healed. Once patients are safe on their crutches and can mobilise normally, they are discharged home. Mr Fehily and his team will usually review them at 6 weeks, 6 months and one year, with regular follow up after that.

Much work has been done to try to lengthen the lifespan of hip replacements. The National Joint Registry can be used to compare different implants and we use robotics to ensure that the implant has been put in perfectly.

The rate of deep hip infection in hip replacements is about 1-2% (see NJR) and can vary from surgeon to surgeon and hospital to hospital. The most common organisms are not MRSA but bacteria that are normally present on the skin and only cause a problem when in the wrong place. The infection will either occur early, often due to contamination at the time of surgery or later due to spread via the bloodstream (hematogenous spread). Surgeons performing the surgery will be wearing suitable PPE so that the spread of human infection is avoided. Patients will usually complain of deep-seated pain if there is an infection. There may have been a history of wound infection at the time of surgery. Often, the patient will say that the joint “never felt right”. Clinically there may be little to find but x-rays may show evidence of loosening and blood tests will be abnormal. The patient will have an abnormal bone scan due to the increased blood supply around the hip and a positive white cell scan indicating the body’s’ attempt to eradicate the infection.

Joint aspiration is carried out in order to confirm the diagnosis of infection and to test which antibiotics it is sensitive to.

Once the diagnosis is made and the patient is optimized, then the revision is often carried out over two stages. During the first, the old implants and cement are removed. Any infected tissue is also removed, leaving only healthy tissue behind. A temporary hip made out of antibiotic laden cement is inserted and the patient remains on intravenous then oral antibiotics for 4-6 weeks.

Once the tissues have healed and the blood tests have returned to normal, then the patient undergoes a second procedure where the spacer is removed and a new hip is inserted.

This type of surgery is called a 2 stage revision. It is possible to do a 1 stage revision but only if the organism is known and not too virulent, a bone graft is not needed and a cemented hip is re-inserted. The success rate for 2 stage is 90-95% and that for 1 stage is slightly less at 85-90%.

What is it?

Open hip debridement is a procedure carried out in patients who are not suitable for hip arthroscopy. If a patient has had childhood hip disease such as Perthes, Slipped Upper Femoral Epiphysis or Avascular necrosis, their hip can often be left deformed and this can lead to the femoral head “impinging” against the rim of the acetabular socket. If the deformity is severe, then it is difficult to ensure that a full correction/reshaping has been carried out arthroscopically. In this cases an open procedure is advised.

Investigations Prior to surgery, all patients undergo a detailed physical examination. They will require plain x-rays and 3 D CT scans to give an accurate image of the deformity and allow pre-operative planning.

Procedure Each patient undergoes a general anaesthetic and the procedure takes approximately 2 hours minutes to carry out. All patients are given intra-venous antibiotics and blood thinning drugs to prevent a blood clot.

An incision is made on the side of the hip and a careful dissection is carried out. A portion of bone is removed from the side of the femur, preserving the muscle attachments and the dissection is continued until the hip joint is accessible. The hip is dislocated and a thorough inspection is made of both the femoral head and pelvic socket. Any abnormalities on the socket or cartilaginous labrum are treated at the stage and the head is reshaped using special instruments. Once that is completed, the hip is reduced and the bony fragment is reattached using screws.

Following the surgery, the patient undergoes an active rehabilitation program. This works on restoring range of movement and muscle strength. The patient is usually partially weight-bearing for at least six weeks while the bony repair heals. Patients are usually in hospital for between 2-4 days and are followed up by a dedicated therapist. They are reviewed in out-patients at six weeks and their progress is carefully monitored.

The speed of patient recovery can vary following the operation and most return to normal activities 6 to 12 weeks following surgery.

Open hip debridement is a significant procedure and the risks are greater than with hip arthroscopy. There is a small risk of infection, blood clots, temporary nerve injury and non-union of the bony fragment. Some patients will get discomfort from the screws and these may need to be removed as a day-case procedure.

The problem of painful hip resurfacing has increasingly been in the national news. Since the 1990’s there has been a significant increase in the number of metal-on-metal hip resurfacings being carried out in the UK. This type of implant was developed in Birmingham and still remains the market leader. It was developed on the basis that it was an ideal implant to use in younger patients, as it conserved bone on the thigh bone side and the large head gave greater stability. However, as more and more implants have been implanted and other companies have developed their own versions, which had different geometries, problems have emerged. It has become clear that a minority of patients will develop soft-tissue reactions due to the production of metal debris which can lead to a painful resurfacing. It seems to be more common in those with smaller femoral head sizes. It is currently only recommended in males under the age of 55 and is not carried out by Professor Fehily due to these problems. Following multiple reports of problems with these implants, the numbers being implanted in the UK have dropped significantly.

Problems have also emerged with implants where there is a large metal head on a stem. Recent evidence has shown that these implants (which were implanted because the surgeons felt that they were more reliable than the resurfacing implants) may actually be doing worse than the resurfacing ones. It is thought that this is due to wear at the junction between the head and the stem.

Patients who do develop problems will usually be within 5 years of their surgery. They will have a deep seated pain. There may or may not be a squeak as the metal components rub against each other.

Plain x-rays may show that the cup was mal-positioned and more vertical then recommended. However problems can occur even in implants that have been well positioned. On the x-ray, there is usually no evidence of loosening and no indication of the soft-tissue damage that may be present.

See our latest blog on metal-on-metal hip replacements…click HERE

Perthes disease is a condition that affects children (often boys) between 4 and 10 years of age. There is disruption to the blood supply of the femoral head, which causes softening of the cartilage and eventually a change in the shape of the femoral head. Once the collapse occurs, the bone then heals and remains abnormally shaped. Because this can occurs at such a young age, the socket can remodel to try to match the head. While this can give the patient a functional hip for some years, once they reach their 20’s or 30’s, degenerative changes can set in and the hip becomes painful.

Once non-operative treatments such as pain-killers and physiotherapy are no longer effective, the only option is to replace the joint. Surgeons have attempted to use arthroscopic techniques to treat this condition but it tends to treat the damage rather then the underlying cause (which is the abnormally shaped head and socket). Inevitably, after a temporary period of improvement, the pain returns. The grossly deformed anatomy can make the surgery technically difficult. The cup can be uncovered and require either screw fixation or bone graft. The upper femoral anatomy can mean that specially designed implants are required.

However, with careful pre-operative planning and meticulous surgical technique, “normal” anatomy can be restored with almost equal leg length. Once the new hip has fully bonded, then patients can return to a full and active lifestyle.

There are a number of childhood conditions such as Perthes disease, Hip Dysplasia and Slipped Upper Femoral Epiphysis (SUFE) which can cause significant abnormalities in the immature hip. There are a variety of ways of treating these conditions but traditionally, they would have been treated with surgery to change the shape of the femur. The picture below shows an x-ray of the right hip in a 40 year old male who had undergone a previous valgus osteotomy. While it gave him relief for some years, he then began to get increasing pain in his hip. X-rays showed that arthritis had set in due to his abnormal anatomy.

These are difficult cases to manage surgically. Because of his previous operation, the shape of his upper femur made a normal hip replacement impossible. To get around this problem, the femur was split again and a corrective osteotomy performed. This allowed the use of a revision stem (s-rom) and a standard uncemented cup with ceramic bearings. While this was a major procedure, it did mean that normal anatomy was restored and the optimal bearings could be used.

This is a condition where there is erosion of the inner wall of the socket (acetabulum) and the femoral head migrates into the pelvis. It is more common in females and can be associated with inflammatory arthritis such as rheumatoid arthritis. They are often very symptomatic and can require high levels of painkillers.

Figure 1: x-ray showing significant protrusio on both sides

These can be technically difficult hip replacements. The hip can be difficult to dislocate and the inner wall very thin and prone to fracture. Depending on the bone quality, the socket may need bone grafting which has a significant effect on post-operative rehabilitation. The femoral side is usually straightforward, but care needs to be taken to restore the original anatomy to ensure optimal function.

SUFE or Slipped Upper Femoral Epiphysis is a childhood condition where there is a fracture through the growth plate of the femoral head. This occurs in early adolescence and usually presents with pain in the groin and occasionally on the front of the knee.

If this condition is detected early, before there is a significant slip, it can be pinned using a screw. While there is a small risk of post-operative complications such as infection and avascular necrosis, most patients will do well without the need for future surgery. If the slip is severe or detected late, it can heal in an abnormal position. Unlike other childhood conditions such as Perthes disease, there is no time for the socket to remodel, so there is a miss-match between the socket and the head.

This miss-match can lead to significant degeneration, even in early adulthood. Even significant deformities may be treatable with conservative types of surgery such as open hip debridement or hip arthroscopy where the head is reshaped, but once the degeneration progresses and there is a loss of joint space, then the only remaining option is a joint replacement.

As in other conditions, this can be demanding surgery. The hip can be quite scared and the abnormal anatomy not amenable to standard implants. However, with meticulous technique, restoration of anatomy can be achieved with the excellent functional result.

Following previous hip surgery, some patients can develop weakness or failure of the muscles/tendons at the side of the hip. This can cause instability of the hip or a waddling walk and eventually pain at the side of the hip.

This can cause instability of the hip or a waddling walk and eventually pain at the side of the hip. Often the tissues are not of good quality so are reconstructed using an artificial ligament (Lars Ligament). When this is combined with a comprehensive and prolonged rehabilitation program, good function can be restored, although not usually to the level that they had before the original hip replacement.