2. INTRODUCTION TO TKR
In this presentation we will go over a step by step procedure of how a total knee
replacement (TKR) is performed.
Knee replacements are performed on people that have severely damaged knees
from degenerative changes and sports injuries.
A knee replacement is mainly performed to allow a person to be more
active, improve function of the knee, and to relieve pain.
When a TKR is performed the surgeon removes the damaged tissues and
cartilage and replaces it with a man-made metal or plastic replacement.
A TKR is performed using many different types of equipment. These include:
tourniquet, nitrogen tank for power instrument, foot holder or foot
bump, suction, and electrical surgical unit (cauterization).
Basic instruments used will also be discussed. These include: basic orthopedic
drill set, power drill, gauges, total knee specialty instrument sets, power
oscillating saw, osteotomes, and drill bits.
3. THE BEGINNING
• The Incision:
• An incision is made in the middle and
front of the knee with the knee
positioned in flexion.
• Another approach is a medial
parapatellar approach.
• The middle side of the knee is then
exposed by removing the anteromedial
knee capsule and medial collateral
ligament from the tibia using a curved
osteotome.
• The leg is then extended and the patella
is everted, then the lateral
patellofemoral plicae is removed with
mayo scissors.
• The knee is once again flexed and the
medial meniscus and anterior cruciate
ligament are removed using mayo
scissors and a rongeur.
4. THE FEMORAL SEGMENT
Femoral preparation: Femoral Resection:
A 3x8 drill bit is used to create an The distal femoral resection is performed.
opening in the femoral canal. The IM reamer and valgus angle alignment
In order to reduce the risk of developing guide are removed.
a fat embolism, a intramedullary (IM) The appropriate sized saw blade is then
reamer is inserted into the femoral canal used to resect the distal femur using the
while irrigating. standard resection guide.
Femoral Alignment: The pins or drill bits along with the
The valgus alignment guide is then used crosshead are removed.
and attached to the IM reamer. It then Femoral Sizing:
rests and is secured on the distal femoral The anterior-posterior femoral sizer is then
condyle. placed against the resected distal femur
The guide is locked into pace by and is adjusted so that the feet rest
tightening a large screw. against the posterior condyles and so that
The distal resection crosshead is locked the point of the stylus hardly touches the
on the valgus alignment guide using a anterior cortex proximal to the anterior
hexagonal screwdriver. condyles.
The surgeon then checks the alignment. The holes that were already made in the
1x8 pins or drill bits are then placed into distal femur are then re-drilled for the
the holes of the crosshead fixing the fixation pegs of the femoral resection block.
anterior femur into place.
5. THE RESECTION
Anterior and Posterior Resection Trochlear Groove Resection
The fixation pegs and pins are The trochlear resection guide is
used to hold the cutting block secured to the femur with pins
against the distal femur. The and the final femoral resection is
calipers are used to measure performed.
the size of the femoral resection The appropriate size saw blade is
block. used for the resection.
The appropriate sized saw The cutting guide is removed.
blade is then used to make the
anterior, posterior, and chamfer
cuts.
The cutting block is then
removed.
6. TIBIAL PREPARATION
• The ankle is positioned and
secured against the lower
portion of the leg proximal
to the malleolus.
• The tibia resection guide is
secured with pins after it is
positioned and centered on
the proximal tibia.
7. CONTINUATION OF TIBIAL PREPARATION
Extra-medullary Tibial Tibial Sizing
Resection A tibial trial handle is attached to the
The medial/lateral adjustment screw trial base which is placed against the
that is placed at the ankle is used to proximal tibial surface.
align the resection guide parallel Alignment is confirmed through the
with the tibia. handle in order to check the
The stylus is then attached to the alignment to the ankle by inserting
crosshead and the crosshead knob the alignment rod.
is turned to raise or lower it until the The keel punch guide is then
level resection is indicated by the attached to the keel punch handle
stylus. and is secured at the trial base.
Pins are then used to fix the The keel punch on the keel punch
crosshead to the proximal tibia. handle is hammered into place using
To check alignment to the ankle an the mallet through the guide until the
alignment rod is used. punch is fully seated.
An appropriate size saw blade is When the punch is seated the keel
then used for the tibial resection. punch handle is removed. This leaves
the tibial trial base and stem in place
for trial reduction.
8. PATELLAR PREPARATION
First the patella is laterally retracted with
the articular surface facing in the upward
position
Calipers are then used to determine the
size of the patella along with the amount
of bone that will be removed.
The patella cutting guide is then placed
to ensure the proper cut of the patellar
apex.
The appropriate size saw is then used to
make the patellar cut.
The patellar peg holding guide is then
placed on the resected patella and the
peg holes are then drilled.
9. FINISHING THE TKR
Trial Reduction: Implant Insertion:
With the knee flexed, using the The femoral impactor and mallet is
mallet and femoral impactor the used to insert the femoral implant
appropriate femoral trial is placed The tibial base impactor and mallet
on the distal femur. are used to insert the metal tibial
The tibial trial insert is then snapped base.
into place on the trial base. The patellar implant is secured with
The knee is then put through a bone cement and held in place using
series of motions to confirm normal the parallel patellar recessing clamp.
movement and alignment. The tibial polyethylene insert is
The trial components are then seated and locked into place on the
removed after the correct fit is metal tibial base.
confirmed. The cement is hardened with the leg
The joint is then irrigated with a placed in 35 degrees of flexion.
pulse lavage.
The cement is then injected on the
cut bone surfaces and the
prostheses are then placed.
10. WOUND CLOSURE AND DRESSING
The wound is thoroughly irrigated.
The tourniquet is then removed and
the bleeding is stopped using
electrocautery.
The surgeons preference is used to
then determine if a closed-suction
drainage device will be needed.
The wound is then closed in layers
and a compressive dressing is
placed on the knee.
11. WORKS CITED
Frey, K.B. Surgical Technology for the Surgical
Technologist. Clifton Park, NY. DelMar
Cengage Learning. 2007. Print. (897-
902).
