Painful or Failed Total Hip Replacement

Failure of Total Hip Arthroplasty

The vast majority of THAs will last many years. Dr. Thornton-Bott, using the latest implant technology, surgical skill and experience would expect a THA to last 25 years or more. Some THAs however, do fail-

How does my Total Hip Replacement fail?

Dr. Thornton-Bott is sub-specialised in revision hip surgery and will use imaging techniques and other tests to identify the cause of failure of your hip replacement. These include-

Aseptic Loosening

The ball and socket joint is a bearing and, like all bearings, it eventually wears out as the ball continually rubs against the socket. It is a little known fact that, in an average active person, the hip moves through two million cycles per year! The bearing wear creates ‘wear debris’, tiny particles of material. With older plastic sockets, called conventional polyethylene (CPE), these particles create a reaction in the human body called osteolysis, which causes the bone surrounding the hip replacement to be replaced with a soft, granular tissue. This tissue has no structural support so, the greater the osteolysis, the weaker the surrounding bone around the implant. When this gets beyond a certain point, the implant becomes loose, and the patient feels pain. If allowed to progress, the remaining weak bone can fracture.

In response to the osteolysis seen in CPE bearings, better plastics were developed and Highly Cross-Linked Polyethylene (HXPE) is now the standard material used in this bearing type. The wear characteristics are much better then CPE and even though wear particles are still created, they do not cause the osteolysis seen with CPE. Other bearing surfaces such as Ceramic and Metal bearings have also been designed that wear much less than plastic Polyethylene bearings. Ceramic wear does not cause osteolysis but metal wear, if excessive, can.

Cemented implants have occasionally been seen to become loose over time as well and, as the implant becomes loose, it can rock in the cement mantle causing rubbing and wear debris, further accelerating there wear and loosening, or the cement mantle itself can pull away from the underlying bone.

Some uncemented, or press-fit implants do not fix properly to the bone at the time of insertion or can become loose later on. A loose femoral stem in this manner will cause thigh pain on initial standing that will often settle when you have walked on it for a short time. Acetabular cup loosening will often present as groin pain, and again, may be painful first thing in the morning or rising from a chair and ease slightly later in the day. This is called ‘Start-Up pain’.

Implant Wear and Failure

It is important to remember that the joint can wear out! The bearing surfaces as discussed above will eventually wear, and in CPE this can cause other problems such as dislocation and metal grinding on metal. In some implants designs, loosening puts extra stress on the implant and the implant itself can break. This is more common in femoral stems than the acetabular cup. The lining of the cup, either polyethylene metal or ceramic can become dislodged and very rarely a ceramic bearing can fracture. Implant failure is very rare, and most implants will last the life of the patient.

Some implants have been shown to have a higher rate of failure, either a design fault or material fault.

Peri-Prosthetic Fracture

With loosening and/or osteolysis the underlying bone can become weakened and can fracture around the implant. This can happen with minimal force. A patient often complains of pain for a period of time before a fracture. Simple trauma, e.g. a fall, can also cause a fracture around a total hip replacement. It is more common to have a fracture around the femoral component, i.e. the thigh bone than around the socket. Depending on the cause and type of the fracture, the stability of the implant may be compromised. If this is the case a revision may be required.

Infection of the Joint.

An infection that is deep within the hip joint and in and around the components of the joint is very rare. If this happens, then the patient usually feels pain and may become clinically unwell. Some infections can grumble on for years undetected and can cause damage to the bone surrounding the implants. If the patient becomes unwell with a bout of sepsis e.g. a urinary tract infection, the bacteria in the blood can get to the implant and settle, starting a Prosthetic Joint Infection (PJI). Other causes of PJI include an infection of the wound following the original surgery and some major dental work. Irrespective of the cause, if the joint becomes infected it will need managing. In an early infection the joint can be opened and thoroughly washed out leaving the implants in place. If, however, the infection is more chronic, then a ‘Two-Stage Revision’ is required. This involves removing all of the implants in one operation, treating the infection for several weeks, and then inserting new implants in a second operation. A special ‘spacer’ will be inserted into the hip at the first operation which allows the patient to walk more comfortably.

Dislocation

Dislocation of the hip can be caused by many things. Wear of the bearing, poorly positioned implants at the original surgery, fracture of the bearing, damage to the ligaments and capsule surrounding the hip joint, infection, trauma.

Dislocation of the THA may require a revision operation. Initially, Dr. Thornton-Bott or an Emergency Doctor will reduce the dislocated hip in ED or the operating theatre, and assess its stability. Depending upon the cause of the dislocation, some joints can be treated with reduction alone, often with hip precautions following the dislocation and gentle physiotherapy to allow the tissues around the hip to settle down. If however, there is more than one dislocation, the hip is identified as very unstable or the dislocation has been caused by other factors such as poor implant position, then revision will be required

Revision of the hip will correct the underlying cause of the dislocation.

Surgical Factors

Unfortunately, a total hip replacement can fail simply because the original surgeon did not do a very good job at putting it in!

All orthopaedic surgeons are taught to perform Total Hip Replacement and Total Knee Replacement during their training. However, as with any skill, the more training you have in a certain area and the more you do it the better you will become and the better your results. Dr. Thornton-Bott is a Sub-Specialist in this field and has extensive experience and Fellowship training specifically in Joint replacement Surgery and Revision Joint replacement surgery and his experience has been focused predominantly in this area since 2006.

Simply put; Dr. Thornton-Bott will strive to identify your hip problem, and use his experience and skills to put it right.