Total hip arthroplasty is the surgical procedure, by which a damaged hip joint is replaced by an artificial one. Since 1960, when the procedure was introduced, millions of people have undergone this operation with excellent results for their life quality. However, despite continuous improvement of techniques and implants, which ensure a life span of many years for this artificial joint, like every other mechanical construction, it remains subject to damaging factors. As a result, an increasing number of patients with total hip arthroplasty get to a point, where they need to undergo a new surgery, in order to have the old implants replaced by new ones. This second operation is called a total hip arthroplasty revision. It is a demanding procedure, which necessitates very careful preoperative planning, specially designed implants, an individualized surgical approach and a large experience. For these reasons, it is performed in large medical centers by experienced surgeons.
The potential causes of joint wear and a need for revision are multiple:
Time lapse: The commonest reason for revision is the wear and tear caused by time. The total hip arthroplasties that have been performed up to now, have a life span, meaning satisfactory performance, of 15 to 20 years. However, friction between contacting surfaces of the implants progressively damages them, causing formation of plastic, cement, ceramic or metal particles. These particles initiate an immune response around the implants, which leads to osteolysis (dissolution of bone). As time passes, the implant that was previously steadily fixed, gets loose, resulting in deformity and instability. The patient feels pain, has difficulty moving and gets to a point where he can no longer walk at all. In fact, once the damaging process begins, it is non-reversible; with passing time it can only get worse. This means, that when revision is indicated, it had better be performed without postponement, because bone loss worsens progressively, creating conditions favourable for a fracture, while at the same time the technical difficulties progressively increase.
Breakage: a less common cause of mechanical deficiency is breakage of implants.
In both above cases intensive bodily activity and significantly increased weight play an important role.
Instability of the joint: for hip arthroplasty to function properly, it is necessary that the ball-shaped head of the femoral implant be permanently inside the acetabulum (cup-shaped cavity of pelvis) implant, just as it happens in a normal joint. This means that the two implants -femoral and acetabular- must be correctly oriented, so that the powerful muscular system and the ligaments around the joint can ensure a large range of movement. Under certain circumstances, however, repeated dislocations necessarily lead to restriction of movement and pain. During the first postoperative days this may be caused by a fall or a false movement of the patient. It can, however, appear later on, due either to patient-related causes, such as neurological disorders and muscle weakness, or to imperfect surgical technique.
Fracture: a fracture of the femoral bone near a corresponding implant may necessitate a revision of the total arthroplasty with replacement of the femoral implant.
Infection: Contamination of arthroplasty may occur days or weeks after surgery, but it can not be ruled out even many years later. The presence of microbial agents in the blood after dental procedures, skin infections, respiratory infections or urinary tract infections can lead to colonization of the prosthesis, that is, to installation of microbes on the implant. Contamination of arthroplasty is manifested by pain, edema and possibly fluid outflow from the incision. As effective antibiotic treatment is not possible, the implant has to be removed and replaced with a new one. In order to ensure the definitive eradication of the germs, replacement of the old arthroplasty is done with two separate operations. In the first, the old prosthesis is removed and a temporary one of cement enriched with antibiotics (spacer) is inserted in its place. After a few months and after all tests show that the microbe has been eliminated, a second procedure is performed, to remove the temporary prosthesis and place the new one.
Particular characteristics of the intervention
The revision of a total hip arthroplasty is an intervention depending on many factors, special for each patient. These include the degree of osteolysis, the condition of the joint, whether the damage concerns the acetabular prosthesis, the femoral one, or both, the type of prosthesis originally used and the potential for inflammation. Therefore, it is an operation that should be designed for each patient individually, based on the specific pre-operative control, in order to select the appropriate method, as well as the specific tools and materials to be used. Its duration is certainly longer than that of the first operation, with greater blood loss and general anesthesia is usually chosen. Postoperative pain is generally mild and can be treated with simple analgesics.
Time for recovery
The time spent in the hospital, as well as the time to rehabilitation, are much longer than those for the first intervention. Generally, walking aids such as a walker should be used for some weeks and in some cases, where grafts are placed, the patient should remain in bed until they are integrated.
Obviously, this is a difficult, painful procedure, which, however, results in elimination of pain and restoring of mobility and quality of life to the patient’s previous levels, before the need for revision arose.