TOTAL KNEE REPLACEMENT
PARTS OF KNEE REPLACEMENT PROSTHESIS
Introduction:
Total knee
replacement is surgical procedure in which the damaged cartilage lining of bone
is replaced with artificial components, thereby eliminating the pain caused by
diseased joint.
The most common
indication is completely worn out knee joint by osteoarthritis. Knee
replacement is also considered in certain arthritic conditions like Rheumatoid
arthritis.
Parts of Artificial knee implant:
The components
of artificial knee replicate the shape of joint surface so as to allow smooth
rolling and gliding movement. Structure and shape of knee joint varies from
person to person and also across the genders. In order to address this, the
implant companies manufacture artificial joints in different sizes so that the
operating surgeon can choose the best fit.
There are also
several designs of implant based on patient’s age, gender and lifestyle. It is the surgeon who can choose and suggest
the best design and brand that best suits your need.
There are three
main parts
-
Femoral
(thigh bone) component
-
Tibial
(Shin bone) component
-
Plastic
(Cushion) component
-
Patellar
component
Femoral (Thigh bone) component:
The lower end of
femur in knee joint is a curved surface with central groove allowing movement
of knee cap. The prosthesis component is made up metal and is curved with
central groove mimicking the natural surface of femur. Femoral component is
made up Chrome cobalt alloy or Zirconium alloy or Oxinium .
Tibial (Shin bone) component:
The upper end of
shin bone is replaced with flat metal platform which can accommodate Plastic
(cushion). Tibial component is made of Titanium alloy or Chrome-cobalt alloy.
Plastic (Cushion):
The plastic
(Cushion) is also called as insert accommodates into the tibial metal platform.
The plastic component has inbuilt curvature to accept the curvature of femoral
component. If surgeon prefers to do a ligament sparing surgery the plastic has
notch to accommodate the cruciate ligaments. In case cruciate ligaments are
removed it has cam to take over the function. The material used in the
manufacturing of plastic is High Molecular Weight Polyethylene (HMWP).
Patellar component:
The back side of
knee cap is also replaced by removing damaged cartilage with polyethylene
button. Some absolute indications warrant’s patella replacement whereas in some
cases its surgeons preference.