Non-Cemented Total Knee Replacement - Dr Anthony …
In a hybrid fixation for total knee replacement, the femoral component is inserted without cement, and the tibial and patellar components are inserted with cement. This technique was introduced in the early 1980s; long-term results are just now being measured and are generally positive.
Non-Cemented Total Knee Replacement
Knee replacement operations, whether they use cemented or cementless fixation, are highly successful in relieving pain and restoring movement. However, the ongoing problems with wear and particulate debris may eventually necessitate further surgery, including replacing one or more parts of the knee replacement (revision surgery).
Cementless implants, however, have not solved the problems of wear and bone loss. In all knee replacement implants, metal (usually a titanium- or cobalt/chromium-based alloy) rubs against ultra-high-density polyethylene. Even though the metal is polished smooth and the polyethylene is treated to resist wear, the loads and stresses of daily movements will generate microscopic particulate debris. This debris, in turn, can trigger the inflammatory response that results in osteolysis.
Non- cemented tibial component for knee prosthesis …
During natural movement, the knee is subject to considerable loads and stresses, which the prostheses must transfer to the underlying bone. Because the hard subchondral bone of the shinbone (tibia) is removed during a knee replacement, loads are absorbed by the softer cancellous bone and the peripheral cortical bone that remains. If loads are heavier than the underlying bone can bear over a long period, the prosthesis will begin to sink into or loosen from its attachment to the bone. Additionally, if the load applied to the knee during walking is uneven, one side of the implant may lift off the bone as the other side is pressed into it, resulting in uneven wear of the polyethylene liner between the metal components. This wear creates debris particles of polyethylene that can trigger a biologic response and further contribute to loosening of the implant and sometimes to bone loss around the implant.
thus creating a potential gap between the prosthesis and the cement
Fracture of the femur including the greater trochanter can occur during insertion of the prosthesis. This problem is usually treated with fixation with cables and/or wires. Intra operative fractures range between 0.1-1.0% with cemented total hip replacements and is increased when using a cementless prosthesis (3-29%).
Cemented and Non-Cemented Knee Replacements During Rehab
Cemented fixation relies on a stable interface between the prosthesis and the cement as well as a solid mechanical bond between the cement and the bone. Metal alloy components rarely break, but they can occasionally come loose from the bone. Two processes, one mechanical and one biological, can contribute to loosening.
Generally with the cemented prosthesis, ..
These can occur from screws which are inserted to hold the acetabular cup in place. Penetration of the femoral bone by the prosthesis can occur with difficult revision hip surgery, particularly in patients with bone stock loss and osteoporosis.