Revision Total Hip Arthroplasty
When 1 or both components of the prosthesis are loosened, a replacement will be mandatory. This is called a revision arthroplasty. There are several reasons for loosening of the prosthesis:
- osteolysis (bone resorption), induced by polyethylene wear particles (aseptic)
- infection (septic)
- fracture (e.g. caused by a fall… )
Revision arthroplasty implicate more extensive surgery with less chance for excellent clinical results.
Revision of the socket (acetabular)
Resorption of the bone (osteolysis) creates large bony defects in the roof of the acetabulum. A new larger press fit cup will be the first option, in condition the cup will be covered for more than 50 % with own bone. When the bony defect is too extensive, a titanium reinforcement ring (type Ganz or BurchSchneider) in combination with donor bone grafting, from our clinic’s own tissue bank, will be necessary. The bone graft and reinforcement ring are fixated by screws in the acetabulum, followed by cementing a polyethylene liner into the ring.
Revision of the stem (femoral)
In case of a cemented stem, all cement needs to be removed first after extraction of the stem. This requires sometimes an extensive femoral osteotomy (type Wagner) of the femur (see figures), to avoid fracture of the femoral shaft. After cleaning up the shaft, a cementless modular stem (type Profemur) is introduced into the shaft. Because of its modularity, the stem exists of 4 different components, allowing a wide range of positioning possibilities in order to obtain the most appropriate biomechanical position.
Revision of a resurfacing prosthesis
In case of failure of the resurfacing shell on the head of the femur, it is easy to remove the head of the femur and proceed with the normal stem procedure of a classical total hip prosthesis. A cemented or cementless stem is introduced into the shaft and a big modular metal head is placed on the neck to form a new metal-on-metal articulation with the original BHR socket. Because of the use of a large ball, the chance for dislocation is very low. In case of failure of the BHR socket, it can be replaced by a classical socket with ceramic-on-ceramic friction couple.
In some cases a revision of the resurfacing cup is possible to a larger cup size of 2.5 mm on average.
Recently, we use a new technique for revision surgery in our clinic, based on the principles of metal-on-metal BHR prosthesis. In the socket, a BHR Dysplasia cup (fixated into the bone with 2 additional screws) or a primary BHR cup is implanted, creating a metal-on-metal articulation with a large metal modular head, placed on the neck of a classical primary or revision stem (type Profemur) in the shaft. In this way, we hope to reduce the chance for dislocation to an absolute minimum (see pdf-file), in combination with the excellent wear properties of the metal-on-metal articulation. Till date we have successfully placed more than 50 BHR Dysplasia cups.
In case of loosening caused by infection, 2 options are available, depending on severity of the infection and type of germ.
1) Replacement of the prosthesis during 1 operation (one-stage technique)
- During the same operation, the prosthesis is removed and replaced by a new one, after extensive cleaning up and removing of al infectious tissues. With this technique, the chance for relapse of infection is about 10 % more, compared to the two-stage technique, described below.
2) Replacement of the prosthesis requiring 2 operations (two-stages technique)
- During the first operation, all prostheses components, all cement and all infectious tissues are removed. After extensive cleaning and debridment, a temporary spacer, containing antibiotics, is introduced into the femoral shaft. The spacer will provide local antibiotics, beside the intravenous antibiotics, during 6 weeks and prevents shortening of the leg. In many cases, patients will be able to ambulate with the spacer.
- During the second operation, 6 weeks later, the new prosthesis is implanted after extensive cleaning up and if there are no more signs of infection. This technique is preferable and gives the best clinical results.
- Sometimes, it is impossible to use a temporary spacer, because there is too much damage with extensive loss of bone. In that case, a skeletal traction in bed for 6 weeks is inevitable, just in order to maintain leg length; however patient will be in bed for 6 weeks!
This kind of surgery causes extensive blood loss, up to 5 – 6 litres!! Blood transfusions are mandatory. Other complications, such as dislocation, are also more frequently after this kind of revision surgery.
Rehabilitation after revision surgery
Rehabilitation is slower and less successful, depending on extensiveness of the surgery and general condition of the patient. Normally, all our patients are allowed for full weight bearing with crutches, starting 5 days after the operation. We believe that the prosthesis should have already intrinsic stability during operation, if not, it is doomed to fail in most cases! The stay in hospital varies from 14 up to 21 days, depending on type of surgery and general condition of the patient.
Complications after revision surgery
Besides the earlier mentioned complications in primary total hip replacement (see complications total hip arthroplasty), one should be aware that the chance for dislocation after revision surgery is much bigger, about 10 % versus 1 % after primary hip replacement. One exception is the revision procedure with the BHR metal-on-metal articulation, using a Dysplasia cup in combination with a large metal modular head on a classical stem. This reduces the chance for dislocation to an absolute minimum.