Failed Hip & Knee Surgery

Conventional, primary total hip replacement is a durable operation in majority of patients. A hip replacement is a mechanical device with parts, most commonly referred to as a " ball and socket," that are assembled before and during the operation. After surgery, this ball-and- socket prosthesis restores movement in the hip throughout the life-span of the prosthesis (Figure 1).

As with any other mechanical device, a total hip replacement can be subject to various forms of mechanical or biological failure. Such a failure may require a reoperation of the hip replacement to address the cause of failure and its consequences. A reoperation of a total hip Dislocations are relatively infrequent, particularly in the healthy patient who carefully follows precautions given by Dr. R.P Singh and physical therapist. However, some patients are predisposed to this complication: the elderly, debilitated patients, or those who get a hip replacement after a hip fracture or after multiple hip surgeries.

Patients who suffered a hip dislocation are predisposed to additional dislocations, as the dislocated ball disrupts the important muscles and ligaments around the hip. Multiple dislocations are infrequent, but in patients who have suffered multiple hip dislocations, Dr. R.P Singh may recommend revision surgery.

Revision surgery is effective in preventing a new dislocation. Prior to surgery, Dr. R.P Singh may request imaging studies to determine the exact position and orientation of the different parts of the replacement. One or more parts may need to be reoriented or completely exchanged during the revision.

In certain instances, Dr. R.P Singh may use a device that "captures" the ball inside the socket (called a constrained socket). The proper healing of the soft tissues around a revised hip is most important for the success of the operation. Therefore, Dr. R.P Singh may recommend wearing a brace for a few weeks after surgery. After surgery, it is important to follow Dr. R.P Singh's advice and to refrain from moving the hip into positions that can generate a new dislocation.

Mechanical Failure (wear, loosening, or breakage):

The parts of a hip replacement which move against one another will slowly wear down during the regular use of the replacement. The younger and the more physically active the patient is, the faster the wear. Continual, repetitive movement of the mechanical parts causes small pieces of hip prosthesis ("wear particles") to break off. Depending on the type of hip replacement, these particles can be made out of plastic, cement, ceramic, or metal.

A patient's immune system will recognize the particles as foreign (not a natural part of the body) and generate an immune response (like an allergic reaction). A strong reaction to the wear particles can result in the destruction of bone around the hip replacement (a condition called osteolysis). If the bone destruction is severe enough, the components of the replaced hip may become loose (Figure 3).

A loose component can move against the surrounding bone, compounding the bone loss. If the bone loss is severe enough, a spontaneous bone fracture can occur (known as a pathologic fracture).

Mechanical wear and tear leading to loosening of the prosthesis (implant) is one of the most frequent forms of mechanical failure. However, other forms of mechanical failure are possible, like breakage of the prosthesis, such as may occur during a trauma like a fall or auto collision (Figure 4).

During revision surgery for wear, mechanical loosening, or breakage, Dr. R.P Singh will remove the worn, loosened, or broken component(s), assess the amount of bone loss, and implant new components. Frequently, a bone graft from a deceased donor (whose tissue is tested for compatibility with the patient) is necessary to rebuild the bone content lost because of the prosthetic failure. In certain instances, when a large amount of bone graft must be utilized, or when the patient's own bone stock is poor quality, Dr. R.P Singh may ask the patient not to bear full weight on the operated leg for a specified period of time after surgery.

Infection of a hip replacement

Infection can occur at any time after surgery. The risk is higher during the first six weeks. The risk of "late" infections after that period is lower. Sometimes, infections unrelated to the hip – for example, in the mouth, gums, or teeth (including after regular dental procedures that involve bleeding gums), or in the lungs, urine, or skin – can cause bacteria to enter the blood stream. This bacteria can then seed and infect a hip replacement, causing hip pain and fever. In the presence of a prosthetic infection, Dr. R.P Singh will attempt to identify the organism (bacteria) that is causing the infection. A hip aspiration may be recommended. The liquid aspirated from the hip will be sent to a laboratory and tested to determine the type of bacteria present and the antibiotics the bacteria are sensitive (susceptible) to. Once an infection in the hip replacement has been diagnosed, several treatment options are possible. The vast majority of treatments include surgery and a course of antibiotics that specifically target the infecting bacteria. The treatment option depends on the type of bacteria and its sensitivity to antibiotics, the duration of the infection, the fixation of the hip replacement parts, and the patient's general health. Dr. R.P Singh will discuss benefits and drawbacks of each treatment option.

The most common treatment options include:

1. A thorough surgical cleaning: of the hip replacement. This is generally recommended when the infection is discovered very early (within a few hours or days). Patients require six weeks of intravenous antibiotics and, frequently, a low dose of oral antibiotics for a long period of time (sometimes for life).

2. A complete exchange of a hip replacement, done in two stages: The first stage consists of the complete removal of the hip replacement, cleaning of the bone, implantation of a temporary cement spacer that will allow some hip motion, and delivering antibiotics to the hip area. This is generally followed by a six-week course of intravenous antibiotics. The second stage consists of the re-implantation of a definitive hip replacement (generally 6 to 8 weeks after the initial operation).

3. A complete exchange of a hip replacement done as a single operation:, During this, the infected prosthesis is removed, the bone is cleaned and a new prosthesis is implanted. Patients require six weeks of intravenous antibiotics and frequently, a low dose of oral antibiotics for a long period of time (sometimes for life).