Revision (re do) of a total knee replacement implies changing one or both components of the artificial knee joint. Knee revisions are needed if there is a problem with the existing knee joint prosthesis. The indications for revision knee surgery include:
Aseptic loosening – This means loss of fixation of the implant in the thigh bone (femur) or the leg bone (tibia). The implant staibility is compromised, but by definition, there is no co-existent infection. This is a long term complication and usually presents many years after primary knee surgery.
- Gross loosening of the tibial component Gross loosening of the tibial component
- Revision of the prosthesis using metaphyseal sleeves on femoral and tibial side Revision of the prosthesis using metaphyseal sleeves on femoral and tibial side
Infection in a primary knee joint will require its removal and insertion of a new implant. Established deep infection in artificial joints is unlikely to respond to administration of antibiotics alone. Revision for infection is often complicated and sometimes needs to be done in two stages to minimise the chances of recurrent infection.
- A white cell labelled radioisotope scan showing increased uptake around an infected knee replacement A white cell labelled radioisotope scan showing increased uptake around an infected knee replacement
- Single stage revision of the knee using a cemented prosthesis Single stage revision of the knee using a cemented prosthesis
Instability of the ligaments after knee replacement surgery can be a cause for pain. Adequate balancing of the ligaments should be achievable at the time of primary surgery in most instances. Significant instability of the collateral ligaments will require revision surgery.
- ligamentous instability following total knee replacement ligamentous instability following total knee replacement
- Revision of the prosthesis using a semi-constrained implant Revision of the prosthesis using a semi-constrained implant
Stiffness – Occasionally, the knee joint replacement surgery results in inability to fully straighten the knee, or loss of range of flexion of the knee. Most patients with stiffness respond to physiotherapy. Sometimes, manipulation of the knee is required. Knees with persistent stiffness, where there is malalignment of the components is managed by revision of the knee.
Periprosthetic fracture – is fracture of the bone adjacent to the knee joint prosthesis, commonly due to a fall or a significant injury. These fractures involve the thigh bone, the leg bone, or rarely the knee cap. The presence of an artificial joint makes conventional fracture fixation techniques unsuitable in these situations. If usual fracture fixation techniques are not possible, then these fractures require changing the knee prosthesis and the use of a new prosthesis with stems to bypass the fracture and provide stability.
- Fracture above the femoral component of total knee replacement Fracture above the femoral component of total knee replacement
- Revision of the implant using a hinged prosthesis Revision of the implant using a hinged prosthesis
Osteolysis – is a long term problem of joint replacements whereby the wear particles generated by joint movement initiate a bone dissolving process. The dissolution of bone around the knee joint results in loss of fixation and in these situations, the knee joint has to be changed and the bone deficient areas addressed.
Most of the discussion relating to primary knee replacement is applicable to revision knee surgery. The notable difference is that revision knee surgery is more extensive, takes longer to perform, has a higher risk of complications and a longer recovery period. The type of implant (prosthesis) used is different to primary knee surgery.
Most patients following revision knee surgery do well, although, statistically, the outcome of primary knee replacement is generally superior to revision knee surgery.
- Gross osteolysis (bone dissolution) around a knee replacement Gross osteolysis (bone dissolution) around a knee replacement
- Revision of the implant and reconstruction of bone defects Revision of the implant and reconstruction of bone defects
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