Aseptic loosening of the total knee:
Causes pain and stiffness in the total knee.
Either the tibial (the lower), or the femoral (the upper) component, or both may become
loose. The loosening may usually be seen on X-rays.
Unstable total knee
When you feel that your total knee is not
stable, the instability may have several causes: the knee may totter because the side
ligaments (collateral ligaments) are flaccid. The knee may buckle backwards because the
stretching mechanism (the quadriceps muscle) is weak. A worn out tibial component may
make the side ligaments (collateral ligaments) too long and make the collateral
ligaments flaccid.
Unstable patella (kneecap)
causes instability and pain in the total knee.
The patient may feel popping of the kneecap, or even describe a sudden
"dislocation" of the whole joint. The cause is often bad position of the total
knee prosthesis, so that kneecap cannot follow the track on the femoral component during
bending and stretching of the knee.
Catastrophic wear and breakage of the total
knee components
occurs more often in patients with severe
deformities in their knees. It may be recognized on the X-ray pictures.
Infection of the total knee
may occur late, months or even years after the
operatation wound healed. It causes severe unremitting pain in the total knee. Sometimes
there occur small openings in the operation wound scar that produce watery liquid.
Laboratory results show signs of infection, although the values may be only marginally
positive. The X-ray pictures show signs of continuing destruction of the skeleton around
the total knee components, especially if the infection was ongoing longer period.
Damage (rupture) of the stretching
mechanism of the knee
is a very serious complication. Most often it
is the rupture of the ligament that connects the kneecap (patella) to the shinbone
(tibia). This ligament is prone to rupture in patients with previous knee operations. The
kneecap itself may also broke apart if it is too thin , for example after previous
operations.
Stiff total knee
The main cause of stiff total knee is
widespread scarring of the muscle that stretches the knee joint. This occurs more often
after repeated previous operations of the knee. But there may be also scaring of
soft tissues around the knee joint caused by the joint disease, such as rheumatoid
arthritis.
Fracture of the skeleton around the total
knee components
occurs most often just above the upper rim of
the (femoral) component of the prosthesis. The causes are poor quality of the bone tissue
(osteoporosis), a notch in the skeleton done during implantation of the femoral component,
and a forcing movement of the stiff knee.
Some of these fractures heal with
immobilization in braces, other need operative treatment.