TOTAL KNEE REPLACEMENT

TOTAL KNEE ARTHROPLASTY
PRESENTER:
MANOJ KUMAR R

INTRODUCTION
Arthroplasty is the surgical reconstruction of a joint which aims
to relieve pain , correct deformities and retain movements of a
joint.
Total Knee Arthroplasty(TKA) is the surgical procedure to
replace the weight-bearing surfaces of the knee joint.
The primary indications for TKA are :
 Relieve pain caused by severe arthritis, with or without
deformity.
 Young patients with limited function due to systemic arthritis
with multiple joint involvement.
 Osteonecrosis with sub-chondral collapse of a condyle.
 Severe Patello-femoral arthritis.
 Severe deformity associated with moderate arthritis and
variable pain.

The contra-indications to TKA are :
 Recent Knee Sepsis
 Source of ongoing infection elsewhere in body
 Extensor mechanism discontinuity or dysfunction
 Recurvatum deformity secondary to muscle weakness
 Painless, Well functioning Knee Arthrodesis

Relative contraindications are numerous and debatable and
can include:
 Medical conditions compromising patient’s ability to withstand
anaesthesia, metabolic demands of surgery and wound healing.
 Severely osteoarthritc ipsilateral hip, which should be operated
first, because it is easier to rehabilitate a THR with OA Knee
than to rehabilitate a TKR with OA Hip.
 Atherosclerotic disease of operative leg
 Skin conditions such as psoriasis within operative field
 Venous stasis disease with recurrent cellulitis
 Morbid obesity
 h/o Osteomyelitis in proximity of knee

The Knee Joint is the largest & complex joint in the body
It consists of 3 Joints:
 Medial Condylar Joint : Between the medial condyle “of the
femur” & the medial condyle “of the tibia” .
 Latral Condylar Joint : Between the lateral condyle “of the
femur” & the lateral condyle “of the tibia” .
 Patellofemoral Joint : Between the patella & the patellar surface
of the femur.

PCL
 Stronger of the two
 Arises from post intercondylar area of tibia, passes sup and ant on
medial side of ACL to attach to the anterior part of lateral surface of
medial condyle of femur
 Tightens during flexion of knee joint
 Preventing anterior displacement of femur on tibia or posterior
displacement of tibia on femur
 Main stabilizer in the weight bearing flexed knee

Movements:
Extension 5 - 10°
Flexion 120° with hip extended
140° with hip flexed
Muscles producing movements:
Flexion Brceps femoris, semi tendinosus,
Semimembranosus assisted by gracilis, Sartorius,
popliteus, gastrocnemius.
ExtensionQuadriceps femories, tensor fascia latae.
Medial rotation Popliteus, semitendinosus,
semimebrnaosus.
Lateral rotation Popliteus, biceps femoris

POPLITEUS:
origin:
popliteus muscle has 3 origins, strongest of which is from lateral
femoral condyle, just anterior and inferior to the LCL origin’
Another origin is from fibula and from the posterior horn of the
lateral meniscus;
Femoral and fibular origins form the arms of an oblique Y
shaped ligament, the arcuate ligament
insertion:
posterior surface of tibia above soleal or popliteal line
popliteus tendon runs deep to LCL and passes thru a hiatus in
the coronary ligament to attach to the femur at a point anterior
and distal to the femoral attachment of LCL

SCREW HOME MECHANISM —
LOCKING AND UNLOCKING OF THE
KNEE

 Knee joint may appear to be a simple joint but its biomechanics
is complex. The knee is a mobile trocho-ginglymus (a pivotal
hinge type of synovial joint).Knee motion during gait occurs in
flexion and extension, abduction and adduction, and rotation
around the long axis of the limb.
 Knee flexion which occurs around a varying transverse axis, is a
function of the articular geometry of the knee and the
ligamentous restraints.
 Dennis et al. described the flexion axis as varying in a helical
fashion in a normal knee, with an average of 2mm of posterior
translation of the medial femoral condyle on the tibia during
flexion compared with 21mm of translation of the lateral
femoral condyle.

Osteokinematics
Gross movements of bones at joints
Flexion / extension
Abduction / adduction
Internal rotation / external rotation
Arthrokinematics
Small amplitude motions of bones at joint surface
Roll
Glide (or slide)
Spin

FLEXION - EXTENSION
Instantaneous centre of motion

FLEXION - EXTENSION
Instantaneous center pathway

Sliding/Rocking of femur
FLEXION - EXTENSION

Knee glides & Slides
Rocks & Rolls!
FLEXION - EXTENSION

Abduction - Adduction
Normal angulation of 7 Degrees with knee extended
Motion permitted by cruciate and collaterals
No movement in flexion

AXIS OF LOWER LIMB
The anatomical axis of the femur and the tibia form a valgus
angle of 6 degrees ± 2 degrees.
The anatomical axis of the tibia is almost vertical.
So the femur is angled off from the vertical, creating a
physiological valgus angle at knee
The mechanical axis of the lower limb is defined as
the line drawn on a standing long leg Anteroposterior
roentgenogram from the center of the femoral head
to the center of the talar dome. This is the Wt. bearing line.

Mechanical axis of the femur and tibia.
Aline from the center of the femoral head to the
centerof the intercondylar notch, and extending
this line distally.
The mechanical axis of the tibia runs from the center
the tibial plateau to the center of the tibial plafond.
 The angle formed between these separate mechanical
axes of the femur and tibia determines the varus or valgus
deviation from the neutral mechanical axis

Knee with the TKA prosthesis:
The aim of the knee replacement is to recreate the normal
biomechanical axis and kinematics of the limb.
Thus the tibial components are generally implanted perpendicular to
the mechanical axis of the tibia in the coronal plane, with posterior tilt
dictated by flexion extension gaps.
The femoral component usually is implanted in 5 to 6 degrees of
valgus, the amount necessary to re establish a neutral limb mechanical
axis.

 During normal gait, mechanical axis is inclined 3 degrees from
the vertical axis of the body, with the feet closer to midline than
the hips.
 When the mechanical axis lies to the lateral side of the knee,
knee is in mechanical valgus alignment and if the axis medial to
the knee joint, it is in varus.
 In normal knee, tibial articular surface is in approximately 3
degrees of varus with respect to the mechanical axis, and
femoral articulating surface is in a corresponding 9 degrees of
valgus.
 Rotational alignment is difficult to discern radiographically,
making intra-op assessment important. The effects of femoral
component rotation are not only on flexion space but also on
patella-femoral tracking

Patellofemoral Joint :
 The primary function of the patella is to increase the lever arm
of the extensor mechanism around the knee, improving the
efficiency of quadriceps contraction. The quadriceps and
patellar tendons insert anteriorly on the patella, with the
thickness of the patella displacing their respective force vectors
away from the center of rotation of knee. The extensor lever
arm is greatest at 20 degrees of flexion and the quadriceps force
required for knee extension increases significantly in the last 20
degrees of extension.

Patellofemoral contact zones :
 The contact areas between the patella and femur changes with
knee flexion.
 At 200 : Inferior surface of patella is in contact with trochlea
 At 600 : Mid portion of patella with trochlea
 At 900 : Superior surface of patella with trochlea
 At 1200 : patella articulates only medially and laterally with the
femoral condyles and quadriceps articulates with
trochlea.Changes in patellar area of contact have a significant
effect on prosthetic patellofemoral joint & patellar tracking

Q angle :
It was described as the angle between the extended anatomical
axis of the femur and the line between the center of the patella
and the tibial tubercle. The quadriceps acts primarily in line with
the anatomical axis of the femur, with the exception of Vastus
medialis obliquis, which acts to medialize the patella in terminal
extension. Limbs with larger Q-angles have a greater tendency for
lateral patellar subluxation. Because the patella does not contact
the trochlea in early flexion, lateral subluxation is prevented by
the vastus medialis obliquis fibres.
As the angle of flexion increase, bony and subsequent prosthetic
constaints play a dominant role in preventing subluxation.
Increase in Q-angle can be caused by :
 Increased external rotation of tibia
 Excessive tibio-femoral angle

CONCEPT OF IDEAL KNEE
 Extends fully & achieves excellent stability.Flexes beyond 110 &
still retains stability
 Gliding and sliding occurs simultaneously.Allows more rotation
as knee flexes
 Articular contact maximum throughout range
 Reduplicate the function of menisci and cruciates
 Achieve excellent ligament balance and have anatomic femur &
tibial surface

FEMORAL ROLL BACK
 the posterior translation of the femur with progressive flexion
 Importance : improves quadriceps function and range of knee
flexion by preventing posterior impingement during deep
flexion
 biomechanics :rollback in the native knee is controlled by
the ACL and PCL
 design implications :both PCL retaining and PCL substituting
designs allow for femoral rollback
 PCL retaining :native PCL promotes posterior displacement of
femoral condyles similar to a native knee
 PCL substituting :tibial post contacts the femoral cam causing
posterior displacement of the femur

 CONSTRAINT
 the ability of a prosthesis to provide varus-valgus and flexion-
extension stability in the face of ligamentous laxity or bone loss
 importance :in the setting of ligamentous laxity or severe bone
loss, standard cruciate-retaining or posterior-stabilized
implants may not provide stability
 design implications :in order of least constrained to most
constrained
 cruciate-retaining
 posterior-stabilized (cruciate-substituting)
 varus-valgus constrained (non-hinged)
 rotating-hinge

MODULARITY
the ability to augment a standard prosthesis to balance soft
tissues and/or restore bone loss
options include
 metal tibial baseplate with modular polyethylene insert
 metal augmentation for bone loss
 modular femoral and tibial stems
advantage :ability to customize implant intraoperatively
disadvantage :increased rates of osteolysis in modular
components and backside polyethylene wear

Hemiarthroplasty (1940)
Hinged Implants(1950)
Biocompartmental Prosthesis(1970)- Duocondylar Knee
Tricompartmental Prosthesis Tibial articular surface
Femoral component
 Meniscal Bearing Prosthesis
 Low Contact Stress Prosthesis
 High Flexion Prosthesis

Types of implants:
Unicompartmental
Indication:
Medial or lateral tibiofemoral
degenerative disease
Contraindications:
a) Inflammatory conditions
b) Damage to articular cartilage
c) Flexion contracture of 5° or
more
d) Preoperative arc of motion
less than 90°
e) Angular deformity of more
than 15°
f) ACL deficiency

Bicompartmental:
Here replacement of the apposing articular surfaces of both the medial
and lateral compartments is done.
Tricompartmental:
Here there is replacement of both medial and lateral articular surfaces of
tibia and femur along with re-surfacing of patellofemoral articulation.
Most of the current complaints are of this design.

Types
Constrained : Are the ones that restrict movement in all planes
a) Hinged
b) Non hinged

Semi-constrained: Here the joint surface alone are replaced. Femoral
components articulate with grooved tibial components.
Currently, almost all TKA's are accomplished with this.
These are sub classified into:
1) PCl retaining design
2) PCl substitution
3) PCl sacrificing design

Components of TKR:
1) Femoral component (metal alloy, right and left, PCl - substituting or
retaining, sizes 1.5, 2, 2.5, 3,4 and 5)
2) Tibial tray (universal for right and left, sizes matching the femoral
components)
3) Patellar button (eccentric, dome shaped with three buttons)

Preoperative evaluation:
Most important part of pre operative evaluation
is determining that TKR Is clearly indicated.
Radiological assessment
Templating of pre operative X-rays
Rule out and evaluate for potential serious vascular
disease in the lower extremity
Assessment of the skin is also important in arthroplasty
Administer a dose of prophylactic antibiotics before
inflation of the tourniquet.

APPROACHES TO THE KNEE
 Surgical approach may be dictated by surgeon preference,prior
incisions,degree of deformity,patella baja,patient obesity
APPROACHES
"simple" primary knee arthroplasty approaches
 medial parapatellar(A)
 midvastus(B)
 subvastus(C)
 minimally invasive
"complex" primary or revision total knee arthroplasty
 lateral parapatellar(D)
 quadriceps snip
 V-Y turndown
 tibial tubercle osteotomy

TECHNIQUE
It consists of:
 Exposure and dislocation
 Bone preparation
 Ligamentous balancing
 Component fixation
 Wound closure

PROBLEMS
KINEMATICS STABILITY DURABILITY
FEMORAL
ROLL BACK
RANGE OF
FLEXION
LIGAMENTS
BONY
GEOMETRY
ALLIGNMENT
FIXATION
PCL
RETAINING
FLEXION
EXTENSION
PCL
SUBSTITUTING

BONE PREPARATION
 appropriate sizing of the individual components,
 alignment of the components to restore the mechanical axis,
 re-creation of equally balanced soft tissues and gaps in flexion
and extension, and
 optimal patellar tracking.

 The anterior and posterior femoral cuts determine the rotation
of the femoral component and the shape of the flexion gap.
Excessive external rotation widens the flexion gap medially and
may result in flexion instability. Internal rotation of the femoral
component can cause lateral patellar tilt or patellofemoral
instability.
 Femoral component rotation can be determined by one of
several methods.
 The transepicondylar axis,
 anteroposterior axis,
 posterior femoral condyles, and
 cut surface of the proximal tibia all can serve as reference
points

 Regardless of the method used of rotational alignment, the
thickness of bone removed from the posterior aspect of the
femoral condyles should equal the thickness of the posterior
condyles of the femoral component. This is determined directly
by measuring the thickness of the posterior condylar resection
with “posterior referencing” instrumentation.
 “Anterior referencing” instruments measure the
anteroposterior dimension of the femoral condyles from an
anterior cut based off the anterior femoral cortex to the
articular surface of the posterior femoral condyles. The femoral
component chosen must be equal to or slightly less than the
measured anteroposterior dimension to avoid tightness in
flexion.

 Posterior referencing instruments are theoretically more
accurate in re-creating the original dimensions of the distal
femur; however, anterior referencing instruments have less risk
of notching the anterior femoral cortex and place the anterior
flange of the femoral component more reliably against the
anterior surface of the distal femur

 Cut the tibia perpendicular to its mechanical axis with the
cutting block oriented by an intramedullary or extramedullary
cutting guide. The amount of posterior slope depends on the
individual implant system being used. Many systems
incorporate 3 degrees of posterior slope into the polyethylene
insert, which allows more accurate slope to be aligned by the

 Before any soft tissue release, remove any medial or lateral
osteophytes about the tibia and femur. Remove posterior
condylar osteophytes because they can block flexion and tent
posterior soft tissue structures in extension, causing a flexion
contracture.
 The flexion and extension gaps must be roughly equal. If the
extension gap is too small or tight, extension is limited.
Similarly, if the flexion gap is too tight, flexion is limited. Laxity
of either gap can lead to instability

INTRAMEDULLARY AND
EXTRAMEDULLARY ALIGNMENT
INSTRUMENTATION

 Intramedullary alignment instrumentation is crucial on the
femoral side of a TKA because femoral landmarks are not easily
palpable. The entry portal for the femoral alignment rod
typically is placed a few millimeters medial to the midline, at a
point anterior to the origin of the PCL
 Extramedullary femoral alignment is useful only in limbs with
severe lateral femoral bowing, femoral malunion, or stenosis
from a previous fracture, or when an ipsilateral total hip
replacement or other hardware fills the intramedullarycanal. A
palpable marker can be placed over the center of the femoral
head based on preoperative hip radiographs or by fluoroscopic
imaging with the patient on the operating table. The anterior
superior iliac spine has been shown to be unreliable for
determining the hip center and should not be used as the
primary landmark when extramedullary femoral alignment is
chosen

 The relative accuracy of intramedullary and extramedullary
tibial alignment also has been debated.Currently most surgeons
prefer intramedullary femoral alignment with extramedullary
tibial alignment

 Soft tissue balancing is essential to providing a stable joint after
TKA. After bone preparation is completed, the flexion and
extension gaps should be evaluated for symmetry for equal
height in flexion and extension. This can be done with laminar
spreaders, spacer blocks, or computer navigation techniques
 Before release of any anatomical soft tissue supporting
structure about the knee, all peripheral osteophytes should be
removed from the femur and tibia. The removal of osteophytes
alone may be enough to balance existing coronal plane
deformities.
 If a tibial resection first technique is being done, the
osteophytes should be removed before determining any bony
cuts on the femur. Eventual knee range of motion can be
restricted by excessive collateral or PCL tension, and excessive
laxity may lead to clinically unacceptable instability.

 As a general guideline, 1 to 2 mm of balanced varus-valgus play
in the prosthetic knee is a reasonable goal.
 Regardless of the type of deformity being corrected, stability
should be checked after each stage of soft tissue release
because overrelease can lead to excessive coronal plane
instability and require conversion to a constrained prosthesis

CORRECTION OF VARUS DEFORMITY:
 IF DOING A PCL STABILIZED TKA,make sure the PCL is
resected before balancing. Because the PCL is a secondary
medial stabilizer, take care not to release the entire soft tissue
sleeve off the tibia because it may overshoot the gap. In general,
less soft tissue release is needed to balance a varus knee once
the PCL is resected.
 Assess the flexion and extension gaps. If the gaps are tight,
release the superficial medial collateral ligament
subperiosteally off the proximal tibia but do not completely
release it off the tibia. Recheck the gaps in flexion and
extension.
 With a cruciate-retaining TKA with the PCL intact, the
release may need to be carried out up to 6 cm distal to the
joint line to effectively balance the gap.

If the extension gap is tight only medially, the
posterior oblique ligament portion can be
subperiosteally released now or later in the soft
tissue balancing procedure. If the extension gaps
remains tight medially, the semimembranosus and
posteromedial capsule can be released.
 If the flexion gap is tight, the anterior aspect of the
superficial medial collateral ligament and the pes
anserinus insertion can be released.
 If the entire soft tissue sleeve is released and the
medial gap is still tight, consider balancing the lateral
collateral ligament.If a posterior drawer maneuver
indicates that the PCL is not functioning, consider
conversion to an anterior-lipped, deep-dish insert

CORRECTION OF VALGUS DEFORMITY

Valgus deformity is common in patients with
rheumatoid and inflammatory arthropathies and
also can occur in those with hypoplastic lateral
femoral condyle or previous trauma or
reconstructive procedures that change the weight-
bearing axis of the lower extremity or tighten the
lateral side of the joint.
 The three-layer anatomy of the lateral side of the
knee joint makes its soft tissue balancing more
complex than with varus deformity. The surgeon
should have detailed knowledge of the three soft
tissue layers to understand the release and balancing
techniques used to correct tight lateral gaps in valgus
deformity

During exposure, release the lateral capsule from the
tibia.
The structure released first depends on whether
both the extension and flexion gaps are tight on the
lateral side. If both are tight, release the lateral
collateral ligament off the lateral epicondyle, taking
care to leave the insertion of the popliteus tendon
intact
 If at any point during the balancing of the valgus
knee only the extension gap is tight, release the
iliotibial band by a Z-lengthening or pie-crusting of
the band 2 cm above the joint line. Make certain all
fibers are released, and evaluate the biceps
aponeurosis to make sure it is not involved in the
contracture.

Release of the posterolateral corner has been shown
to effectively increase the extension space more than
the flexion space and should be considered before
release of the lateral collateral ligament if only a
small amount of correction is needed.
 Release of the popliteus tendon will increase the
flexion gap laterally more than the extension gap.
 If the knee is still not balanced in full extension after
release of all of these structures, release the
posterior capsule off the lateral femoral condyle;
then release the lateral head of gastrocnemius if
further correction is needed.

CORRECTION OF FLEXION
CONTRACTURE

Most preoperative flexion deformities improve with
appropriate soft tissue balancing for coronal plane
deformity. If a flexion contracture persists despite
balanced medial and lateral soft tissues, the
shortened posterior structures must be effectively
lengthened. If the contracture persists, the joint line
may need to be elevated by increasing the amount of
distal femoral bone resection. With severe flexion
contracture, elevation of the joint line more than 4
mm should be avoided because it can create mid-
flexion instability, and an increase in implant
constraint may be necessary.

If necessary, release the posterior capsule further by
stripping more proximally up the posterior aspect of
the femur and releasing the tendinous origins of the
gastrocnemius muscles if necessary.
If the flexion contracture persists, increase the distal
femoral bone cut by 2mm and re-check to see if the
knee will move into full extension with the trial
components in place. This can be increased by
another 2 mm (total of 4 mm over a matched
resection), but make certain that mid-flexion
instability does not exist

Bone deficiencies encountered during total knee
replacement can have multiple causes, including
arthritic angular deformity, condylar hypoplasia,
osteonecrosis, trauma, and previous surgery such as
HTO and previous total knee replacement. The
method used to compensate for a given bone defect
depends on the size and the location of the defect.
Contained or cavitary defects have an intact rim of
cortical bone surrounding the deficient area,
whereas noncontained or segmental defects are
more peripheral and lack a bony cortical rim

Small defects (<5 mm) typically are filled with
cement Contained defects can be filled with
impacted cancellous bone graft.
 Larger noncontained defects can be treated by a
variety of methods, including the use of structural
bone grafts, metal wedges attached to the prosthesis,
or screws within cement that fills the defect

Convert the concave, irregular defect to a flat one by
minimal bone removal with a saw
Attach bone removed from the distal femur or
proximal tibia to the flattened defect, and secure it
with threaded Steinmann pins or screws
 Carefully recut the upper tibial surface to create a
flat upper tibial surface.
 During cementing, premix a small batch of cement
and use it to seal the junction of the bone graft with
the tibia to prevent extrusion of cement into this
interface during final component cement fixation.

Patellofemoral tracking is affected by multiple
factors, each of which must be inspected during trial
reduction and before final component implantation.
Any factor that increases the Q angle of the extensor
mechanism can cause lateral maltracking of the
patella.
Internal rotation of the tibial component lateralizes
the tibial tubercle, increasing the Q angle and the
tendency to lateral patellar subluxation. Similarly,
internal rotation or medial translation of the femoral
component can increase lateral patellar subluxation
by moving the trochlea medially

If the patella is to be resurfaced, the prosthetic
patella should be medialized to approximate the
median eminence of the normal patella, rather than
simply centering the prosthetic button on the
available bone .
Centralization of the patellar component requires
the bony patella to track medially, which forces it to
function with a higher Q angle. Increasing the
anterior displacement of the patella during knee
motion also can lead to patellar instability or limited
flexion. Anterior displacement can be caused by
placing the trochlea too far anterior with an
oversized femoral component or by underresection
of the patella, which results in an overall increase in
patellar thickness

POSTOPERATIVE MANAGEMENT
 Postoperative physical therapy and rehabilitation greatly
influence the outcome of TKA. Initially, a compressive dressing
is worn to decrease postoperative bleeding and a knee
immobilizer may be used until quadriceps strength is adequate
to ensure stability during ambulation.
 Range-of-motion exercises are performed postoperatively, with
or without the assistance of a continuous passive motion
machine.
 In addition to range-of-motion exercises, the postoperative
rehabilitation protocol includes lower extremity muscle
strengthening, concentrating on the quadriceps; gait training,
with weight bearing as allowed by the particular knee recon-
struction; and instruction in performing basic activities of

THROMBOEMBOLISM
 One of the most significant complications after TKA is the
development of deep venous thrombosis (DVT), possibly
resulting in life-threatening pulmonary embolism (PE). Factors
that have been correlated with an increased risk of DVT include
age older than 40 years, estrogen use, stroke, nephrotic
syndrome, cancer, prolonged immobility, previous
thromboembolism, congestive heart failure, indwelling femoral
vein catheter, inflammatory bowel disease, obesity, varicose
veins, smoking, hypertension, diabetes mellitus, and myocardial
infarction.
 The overall prevalence of DVT after TKA without any form of
mechanical or pharmaceutical prophylaxis has been reported to
range from 40% to 84%
 Thrombi in the calf veins have a propensity to propagate
proximally, as documented in 6% to 23% of patients.

MANAGEMENT:
 Many methods of DVT prophylaxis are available, including
mechanical devices such as compression stockings or foot
pumps and pharmaceutical agents such as low-dose warfarin,
low-molecular-weight heparin, fondaparinux (a pentasaccha-
ride factor Xa inhibitor), and aspirin.
 Mechanical compression boots and foot pumps are
advantageous because they are without significant risk to the
patient, but they are limited by patient compliance and short
duration of hospitalization.

INFECTION
 Infection is one of the most dreaded complications affecting
TKA patients, with reported frequencies of 2% to 3% in several
large series.Preoperative factors associated with a higher rate
of infection after TKA include rheumatoid arthritis (especially
in seropositive men), skin ulceration, previous knee surgery,
use of a hinged-knee prosthesis, obesity, concomitant urinary
tract infection, steroid use, renal failure, diabetes mellitus, poor
nutrition, malignancy, and psoriasis.

 The diagnosis of infection after TKA should begin with a careful
history and physical examination. The timing of an infection can
have a profound effect on the outcome of its treatment and
should be used in guiding treatment decisions. Infection should
be considered in any patient with a consistently painful TKA or
an acute onset of pain in the setting of a previously pain-free,
well-functioning arthroplasty. A history of subjective swelling,
erythema, or prolonged wound drainage suggests TKA sepsis,
but these signs are not uniformly present. Swelling, tenderness,
painful range of motion, erythema, and increased warmth of the
affected limb may accompany a TKA infection

MANAGEMENT
 Efforts to reduce bacterial contamination, optimize the status of
the wound, and maximize the available host response should be
employed to minimize postoperative sepsis.
 Prevention of infection in TKA begins in the operating room,
with strict adherence to aseptic technique. The number and
ingress and egress of operating room personnel should be
minimized as much as possible. Operating room surveillance
with adherence to such policies has been shown to decrease the
incidence of postoperative infection in total joint replacement.
 The use of filtered vertical laminar flow operating rooms, body
exhaust suits, and prophylactic antibiotics has greatly reduced
postoperative infection rates in total joint arthroplasty

 When the diagnosis of infection is established, treatment
options include antibiotic suppression, débridement with
prosthesis retention, resection arthroplasty, knee arthrodesis
one-stage or two-stage reimplantation, and amputation
 . The choice between the various options depends on the
general medical condition of the patient, the infecting organism,
timing and extent of infection, the residual usable bone stock,
status of the soft tissue envelope, and extensor mechanism
continuity.

PATELLOFEMORAL COMPLICATIONS
 patellofemoral instability,
 patellar fracture,
 patellar component failure
 patellar component loosening
 patellar clunk syndrome, and
 extensor mechanism rupture

NEUROVASCULAR COMPLICATIONS
 Arterial compromise after TKA is a rare but devastating com-
plication that occurs in 0.03% to 0.2% of patients, with 25%
resulting in amputation.
 Peroneal nerve palsy is the only commonly reported nerve
palsy after TKA, with a reported prevalence of less than 1% to
nearly 2%.
 Mild palsies may recover spontaneously and not be reported.
Peroneal nerve palsy occurs primarily with correction of
combined fixed valgus and flexion deformities, as are common
in patients with rheumatoid arthritis. Suggested risk factors for
peroneal palsy after TKA include postoperative epidural
anesthesia, previous laminectomy, tourniquet time of more than
90 minutes, and valgus deformity

PERIPROSTHETIC FRACTURES
 Supracondylar fractures of the femur occur infrequently after
TKA (0.3% to 2%). Reported risk factors include anterior
femoral notching, osteoporosis, rheumatoid arthritis, steroid
use, female gender, revision arthroplasty, and neurological
disorders. The anterior femoral flange of condylar-type
prostheses creates a stress riser at its proximal junction with
the relatively weak supracondylar bone.

TREATMENT
 Treatment of femoral fracture after TKA has varied, with early
studies generally recommending nonoperative management.
More recent studies have favored operative treatment by a
variety of techniques: open reduction and internal fixation
using blade plates, condylar screw plates, and buttress plates
with bone grafting; Rush pins inserted under image
intensification with minimal surgical dissection; or fixation with
a locked supracondylar intramedullary nail

 Tibial fractures below TKAs are uncommon. Felix, Stuart, and
Hanssen classified these fractures on the basis of their location,
implant stability, and timing (intraoperative vs. postoperative).
Fractures associated with loose implants are treated with
revision, bone grafting, and stemmed implants as needed.
Nondisplaced, stable fractures with well-fixed implants are
treated nonoperatively; displaced fractures with well-fixed
implants are treated with internal fixation

Causes of failure of TKA:
1)Sepsis
2) Component loosening
3) Instability/ligamentous laxity
4) Polyethylene wear with osteolysis
5) Periprosthetic fractures
6) Patellofemoral complications

COMPUTER-ASSISTED ALIGNMENT
TECHNIQUE
 The technique involves the attachment of active or passive
trackers on the femur and the tibia, which are then tracked by a
computer-assisted camera, which must have a clear line of sight
during the procedure The markers are removable from a
reference base that is anchored to the bone to ensure that they
are not damaged or loosened during the procedure.
 Once the trackers are attached to the reference bases, the
surgeon typically performs a registration of the anatomical
landmarks so that the computer can determine and track the
femoral and tibial anatomy during the procedure to guide the
surgeon in alignment of the bony cuts and implants.

 The anatomy within the surgical field typically is registered
using a pointing device that has markers that the computer can
track, and the center of the femoral head is determined by
indirect means of a center-of-rotation mathematical algorithm.
Palpated landmarks of a combination of center-of-rotation and
external landmarks can be used to determine the center of the
ankle.
 Once the registration is complete, the computer can give real-
time feedback about the alignment of the bony cuts of the femur
and tibia in all three anatomic planes, which allows the surgeon
to make changes and to measure the accuracy of the bony cuts
rather than relying solely on the alignment of the cutting jig,
which may not translate into an accurate bony cut because of
sclerotic or osteopenic bone

 Computer navigation systems also can aid in determining the
proper implant size as well as alignment. Soft tissue balancing
and measurement of flexion and extension gaps during the
procedure are other significant advantages to computer-
assisted TKA.
 Objective measurement of the gaps ensures proper soft tissue
balancing and gaps that will provide a stable joint throughout a
range of motion.
 Another advantage of computer navigation is avoidance of
violation of the femoral intramedullary canal, which may
reduce blood loss and cardiac-related complications because
fewer emboli are placed into the venous system than with
placement of an intramedullary alignment rod.

UNICONDYLAR KNEE ARTHROPLASTY
 This simply means that only a part of the knee joint is replaced
through a smaller incision than would normally be used for a
total knee replacement. Unicondylar knee replacements have
been performed since the early 1970's with mixed success..
Recent advances allow us to perform this through a smaller
incision and hence is not as traumatic to the knee making
recovery quicker.
 Important selection criteria include an intact anterior cruciate
ligament, unicompartmental arthritis, passively correctable
deformity, and reasonable body weight
 Just as in primary TKA, the differences between fixed and
mobile-bearing techniques involve strict adherence to
equalization of flexion and extension gaps to avoid bearing
“spit-out.”

Although historically controversial, new interest in
patellofemoral arthroplasty over the past few years
has been fueled by contemporary implant designs
that have produced improved clinical outcomes
The ideal candidate for patellofemoral arthroplasty
is a patient who is younger than 65 years of age and
has debilitating, isolated patellofemoral arthritis
with no malalignment of the patellar mechanism
Good results have been reported after patellofemoral
arthroplasty in patients with posttraumatic arthritis,
primary patellofemoral osteoarthritis, and
patellofemoral dysplasia without malalignment
Patellofemoral arthroplasty alone cannot correct
patellar malalignment, and instability of the
patellofemoral joint is not an indication for the
procedure

TIME CONSTRAINTS
REVISION TKA
UNICONDYLAR ARTHROPLASTY
PATELLOFEMORAL ARTHROPLASTY
UNCEMENTED TKA

TOTAL KNEE REPLACEMENT

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