Alignment of the axes
In a normal knee, there are two axes:
Mechanical axis: this is a straight line that connects the femoral head, passes through the knee and the center of the ankle joint.
Anatomical axis: this is a straight line that passes through the bone shaft of the femur as well as the tibia
On the femoral side, there is 5-7 degrees of angular difference between the anatomical axis and the mechanical axis, whereas the axes are parallel on the tibial side.
In a deformed knee these angles deviate from the nominal values and hence bone cuts have to be made at specific angles in order to achieve appropriate alignments on the femoral as well as tibial side.
This is one of the critical goals of the Total Knee replacement procedure and hence several precision instruments are provided that produce artificial prostheses in order to enable the surgeons to measure the deviations and plan for appropriate cuts to achieve alignment between the axes and the components.
The surgeon goes through the following bone cuts on the distal femoral end and proximal tibial side once the appropriate plan is made based on the axes alignments.
Note: All surgeons do not follow the exact sequence of cuts listed above. They differ based on their preferences and surgical training.
and based on these techniques, the instrumentation is used.
Once the satisfactory cuts are made and the trailing is done, the actual components (Femoral component, tibial component and poly liner) are fixed with the help of bone cement. Implanting prosthesis in Total Knee Replacement
Once the knee surgery is completed, the patient will be transferred to a room for close observation of vital signs, circulation, and pain management. Once the patient is awake, you may notice the following:
Usually, you can expect a big improvement in flexibility and much less pain within a month. It is important to exercise your knee often; initially you will need help of physiotherapist to keep down swelling and to strengthen your muscles.
One of the first priorities is to get your new knee moving – to regain the range of motion.
Following total knee replacement surgery, patients are encouraged to resume an active lifestyle.