- See:
-
Femoral Componenet:
-
Joint Line Position
- Resection of the Distal Femur:
- cushing rongeur is used to remove osteophytes in medial & lateral aspects of the femoral condyles as well as the intercondylar space;
- this avoids, possible mis-sizing of the femoral component;
-
femoral IM alignment rod:
- this is inserted w/ care not to insert it too posteriorly, which would have the effect of flexing the femoral component;
- generally the drill needs to be inserted 1 cm above the notch to enter into the center of the canal;
- the rod should be inserted slightly medial to the notch, just above the PCL insertion;
- if the rod is inserted too laterally, the distal cut will be made in excessive valgus;
-
distal femoral cutting guide:
-
depth of cut:
- generally this is set for a length which makes up for the length of the femoral component (usually 8-9 mm);
- often surgeons will add, 1-2 mm to this length;
- if the patient has a knee flexion contracture, then consider cutting upto 2-3 mm beyond the templated length of the femoral component;
- note, however, that it is important to avoid
elevation of joint line, in which case the surgeon should select a
posterior stabilized knee
rather than a
PCL retaining component:
-
angulation of cut:
- ideally the tibio-femoral articulation should have an angulation of 3 to 7 deg;
- in the early total knee arthroplasty designs, the proximal tibia was cut in upto 3 deg of varus, which meant that the distal femoral cut
was made in 7 to 9 deg of valgus;
- if the proximal tibial cut is to be cut in neutral (this is now standard), then the femoral cutting guide is set for the appropriate right or left
valgus angulation of +5 to 7 deg (in the tall thin patient try +5 deg, & in short obese patient try 7 deg);
Effect of a cooled saw blade on prosthesis fixation. Randomized radiostereometry of 33 knee cases.
S Toksvig-Larsen and A Lindstrand.
Acta Orthop. Scandinavica. Vol 65: 1994. p 533-537.
On the problem of heat generation in bone cutting. Studies on the effects on liquid cooling.
S Toksvig-Larsen.
JBJS. Vol 73-B.(1) 1991. p 13-15.
The Variability of Intramedullary Alignment of the Femoral Component During Total Knee Arthroplasty.
- Johnson and Johnson:
