D.W. LENNOX, L.H. RILEY Jr, D.S. HUNGERFORD, M.A. JACOBS,
JUDET and K.A. KRACKOW
Atlas of Orthopaedic Surgery
Editors: Laurin, CA, Riley Jr. LH, Roy-Camille R
Reprinted with permission from Masson, copyright Masson, Paris,
of the knee
by D.W. LENNOX and L.H. RILEY Jr.
Synovectomy of the knee is performed through a long anterior,
midline incision (Fig. 15-I). The capsule and tendon
of the knee extensors are opened in the medial parapatellar
region, taking care to spare the muscle fibres (Fig. 15-2).
The patella is reflected lateral to the lateral femoral condyle
permitting the knee to be flexed beyond 90 degrees (Fig. 15-3).
The infrapatellar fat pad and overlying synovium are removed
and the medial one third of the patellar tendon insertion into
the tibial tubercle may be divided to facilitate patellar eversion.
Sufficient exposure is thus achieved to permit a complete synovectomy.
- The skin incision extends from just superior to the
musculo-tendinous junction of the knee extensors across
the medial one third of the patella and ends just distal
to the tibial tubercle.
15-2. - The capsule and knee extensors are
incised in the medial parapatellar region.
The patella is reflected lateral to the lateral femoral
condyle permitting the knee to the flexed beyond 90°.
The infrapatellar fat pad is removed.
With the knee in full extension, the synovium of the suprapatellar
pouch is identified and sharply dissected from the underlying
soft tissues and the anterior condyles of the femur (Fig. 15-4).
Proximally, the fibres of the retractor synovialis which
insert into the synovium are sharply divided. As the synovial
layer is dissected distally care is taken to avoid injury to
the fat which separates the synovium from the underlying femur.
The knee is then flexed to 90° to permit the synovium to be
sharply dissected from the medial femoral condyle and from the
medial capsular pouch. At this stage, the patella and lateral
capsular pouch are reflected to permit dissection of the synovium
from the lateral femoral condyle. Care must be taken to remain
in the proper plane over the medial and lateral femoral condyles
to prevent transection of the femoral attachments of the medial
and lateral collateral ligaments which can be damaged if the
dissection is carried down to bone. The synovial flap is detached
at the femoral joint line and, inferiorly as dissection is extended
in the plane between the synovium and the capsule medially and
laterally, down to the capsular attachments to the tibia (Fig.
With the knee in full extension, the synovium of the suprapatellar
pouch is sharply dissected from the underlying soft tissue
to the articular surface of the femoral condyles.
Synovium is sharply dissected from the medial and lateral
femoral condyles: the dissection is extended in the plane
between the capsule and synovium to their tibial attachments.
The synovium of the posterior medial compartment is visualized
with the knee in 90° of flexion through a curved incision in
the capsule, just posterior to the medial collateral ligament,
and can be removed with sharp dissection or with pituitary forceps
(Fig. 15-6). The synovium in the posterolateral compartment
is removed in a similar fashion through a curved capsular incision
just posterior to the lateral collateral ligament with the knee
flexed beyond 90° (Fig. 15-7).
Exposure of the posteromedial compartment and synovial
Exposure of the posterolateral compartment and synovial
The synovium covering the cruciate ligaments is removed with sharp
dissection or with pituitary forceps.
Suction drains are left in the medial and lateral compartments.
The capsule is closed with interrupted nonabsorbable sutures;
the subcutaneous fascia is closed with fine interrupted sutures
and the skin is closed with either a running stitch of nonabsorbable
suture or with skin staples (Fig. 15-8). A compression dressing
is applied. When incisional healing is assured, the knee is
placed in a continuous passive motion machine and 90° of motion
are usually regained within seven days. Extension exercises
are begun on the first postoperative day and continued throughout
the rehabilitative period. Protected weight-bearing is permitted
as soon as muscle control is sufficient.
2. Technique of total
by D.S. HUNGERFORD
Technical inaccuracy is the most common cause of aseptic loosening
following total knee replacement. Indeed, even relatively constrained
designs, which have subsequently been superseded by more anatomical
and kinematically physiologic designs, have shown long term
durability when properly implanted with perfect alignment, component
positioning and ligamentous stability.
Initially, instruments to implant total knee components were
overly simple and relied mostly on free visual referencing by
the surgeon. The technical achievement varied considerably from
case to case, and surgeon to surgeon, since the alignment references
were incompletely visualized. Instrumentation systems have gradually
become more sophisticated and comprehensive leading not only
to the proper triaxial placement of each component, but also
assisting in ligament balancing with intimate contact between
the individual prosthetic components and the host bone. The
latter is of critical importance for the cementless prostheses.
Different surgeon/engineer groups have chosen different routes
to achieve common goals. However, they all stress the importance
of proper alignment, ligament balance, and prosthetic bone contact.
It is beyond the scope of this chapter to review all the instrumentations
system currently available since they are based upon different
premises and, to a certain extent, differing alignment criteria.
However, there is more in common among various systems than
there are differences. The purpose of this section is to review
the alignment requirements for a well functioning total knee
replacement, and to review in some detail the specific operative
sequence that the author is currently using.
IN TOTAL KNEE REPLACEMENT
alignment in total knee arthroplasty is discussed, most people
first think of long axial alignment or the overall orientation
of the leg in the frontal plane (Fig. 15-9). Alignment of the
normal leg averages 6° of valgus between the femoral shaft and
the tibial shaft. (Insall, Kapandji). During single leg stance,
the joint line is horizontal and it makes, on average, an
81° angle with the femoral shaft. The mechanical axis, a line
from the center of the femoral head to the center of the ankle,
normally passes through the center of the knee. It is more difficult
to obtain a standard measurement when using the tibial shaft
as a reference, since the proximal tibial diaphysis may
not be in the same line as the distal diaphysis. Therefore,
the line between the center of the knee and the center of the
ankle is often substituted for the tibial shaft axis. The tibial
shaft axis or mechanical axis makes, on average, an 87° medial
angle with the joint line. In a normal population, the joint
line is virtually never perpendicular to the mechanical
15-9. - Schematic drawing showing normal leg
alignment with the lower extremities positioned for single
leg stance. HKA: Mechanical axis. SKA: Anatomical axis.
TT: Transverse axis. V: Vertical axis.
instrumentation systems recommend cutting the proximal tibia
perpendicular to the mechanical axis and compensating for this
relative valgus cut on the tibia by making a 6° cut on the femur.
In fact, if this is carried out on the normal knee, it results
in removing a 3° laterally based wedge from the tibia which
is compensated by the 3° medially based wedge on the femur (Fig.
15-10 a). However, this balance occurs only with the
knee in full extension, and is not compensated for when the
knee is in flexion unless the femoral cutting block is also
rotated into external rotation (Fig. 15-10 b). This practice
is recommended by Insall and the instrumentation of Scott and
Thornhill for the PFC knee provides an adaptation to laterally
rotate the femoral component 3° while using the medial posterior
condyle as a rotational reference. We prefer to make a 9° valgus
femoral cut and a 3° varus tibial cut to achieve normal alignment
in the frontal plane (Fig. 15-11). However, the whole issue
of alignment is much more complex than only axial alignment.
2° Rotational alignment
rotational position of the femoral component will define the
posterior joint line which will influence medial and lateral
compartment stability when the knee is in flexion, as well as
the orientation of the trochlea. Trochlear position will influence
the stability and tracking of the patellofemoral joint. Therefore,
correct rotational position of the femoral component is important
to the functional kinematics of the replaced knee. Available
references for correct rotational alignment include the posterior
condyles, the “skyline” view appearance of the trochlea, with
the lateral facet projecting more anteriorly than the medial
facet, and the level of the epicondyles (Fig. 15-12). Of these,
the level of the posterior condyles is probably the most reliable,
but may be subject to variability in instances of fracture,
severe deformity or osteonecrosis. In such cases the secondary
alignment references will also be employed. In fact, the secondary
references should always be used to check the validity of the
alignment of the tibia will primarily affect patellofemoral
tracking, but marked rotational malalignment will also affect
the relative position of the collateral ligaments and hence
tibio-femoral stability. Alignment references for the proximal
tibia are less well-defined than for the distal femur, but include
the posterior margin of the tibial plateau, the tibial tubercle,
and the transmalleolar axis (Fig. 15-13). In general, the final
selection of tibial rotation will usually be made after
provisional trial reduction.
End on view of the distal femur. The posterior margins
of the condyles mark the coronal plane (1). The medial
epicondyle is slightly anterior to the lateral epicondyle.
The lateral trochlear facet is anterior to the medial
Top view of the tibial plateau. The tibial tubercle
is slightly lateral to the midline. In general, the posterior
margin of the plateaus parallels the transverse axis of
type patellar components require no rotational orientation.
The original anatomical PCA patellar component requires
rotational orientation after the coronal cut of the facets is
made. The orientation of the longitudinal ridge separating the
medial and lateral facets is noted prior to the patellar resection,
and the patellar resurfacting component will be aligned in this
plane. The dome patella is not rotationally constrained, and
precise rotation is not critical.
Flexion. - Because of the curvature of the femoral condyles,
minor flexion-extension malalignment of the femoral component
will be tolerated relatively well. The flexion-extension alignment
reference is the long axis of the femoral shaft seen from the
side (Fig. 15-14). Early alignment systems used external guides.
Many current systems use an intramedullary rod. Significant
tilting of the femoral component in flexion will tend to bring
the posterior condyles of the femoral component more anteriorly
and contribute to instability in flexion. In addition, most
total knee components allow only limited heperextension and
excessive flexion of the femoral component will impose a fixed
flexion contracture on the definitive prosthesis. With marked
flexion of the femoral component, the anterior patellar flange
could project even more anteriorly than the femoral cortex and
could interfere with the quadriceps mechanism.
The long axis of the femur, as seen from the side, serves
as the flexion extension alignment reference (1)
for the femoral component.
Extension. - Extension of the femoral component will lead
to hyperextension of the knee. The patient may also develop functional
instability when the knee is in anatomical full extension since
the prosthetic components will not be fully extended and, therefore,
be less stable. Additionally, extending the femoral component
will likely lead to notching of the anterior femoral cortex.
flexion-extension attitude of the tibial component is much more
critical to proper knee functioning than the femoral component.
The natural, posterior inclination of the tibial plateau decreases
the distance between the femoral and tibial-fibular attachments
of the collateral ligaments during knee flexion (Fig. 15-15).
The collateral ligaments are therefore relaxed in flexion which
allows rotation between the tibia and the femur to take place.
This possible rotation is important when changing direction
during gait. This means that rotational movements, which will
naturally be imposed in everyday living, will be dissipated
by rotational movement between the femur and the tibia, or,
in the case of total knee replacement, between the femoral and
tibial components. In the absence of rotational freedom, torsional
forces will be resisted by the components and lead to shear
forces at the prosthesis-bone interface.
are, basically, two ways to duplicate this important anatomical
configuration. The first is to slope the tibial cut in the same
way as the natural proximal tibia is sloped, i.e. 7° to 10°
posteriorly. The second way is to cut the tibia perpendicular
to the longitudinal axis and tighten the radius of curvature
of the femoral component to offset the difference between the
amount of posterior tibial bone that is resected and the amount
that is replaced by the tibial prosthesis (Fig. 15-16). Sloping
the tibial cut posteriorly has the disadvantage of resecting
more posterior bone than would, otherwise, be necessary. Secondly,
a posteriorly sloped cut will frequently result in transection
of the tibial attachment of the posterior cruciate ligament,
particularly if there is already significant bone loss on either
of the tibial plateaus.
The posterior slope of the tibial plateau contributes
to the decreased distance between the femoral and tibial
attachments of the collateral ligament in flexion (a)
compared to extension (b).
Composite drawing of the resected bone replaced by the prosthesis
to eliminate the posterior wedging phenomenon.
the PCA prosthesis, we have chosen to cut the tibia perpendicalar
to the longitudinal axis, thus protecting the posterior cruciate
attachment to the tibia and preserving stronger subchondral
posterior tibial bone. It is important that the user be familiar
with the design of the particular prosthesis that he chooses,
since variation in the orientation of the tibial cut from that
which is designed for the specific prosthesis will lead to undesirable
flexion and extension characteristics of the replaced knee.
the tibial component is cut with an anterior slope (extension),
instability in extension will be produced. If a sufficiently
thick tibial component is used to produce stability in extension,
the knee will be too tight in flexion. This will occur whether
the design of the prosthesis calls for a transverse tibial cut
or one which is sloped posteriorly. If the tibial cut is sloped
more posteriorly than intended for the specific prosthesis,
the knee will be unstable in flexion. If a sufficiently thick
tibial component is used to stabilize the knee in flexion, a
fixed flexion contracture will be introduced.
are few guidelines for the proper flexionextension attitude
of the patellar cut. It is, therefore, important that osteophytes
around the patella be debrided and that the marginal insertions
for the quadriceps tendon, the retinaculae and the patellar
tendon be well identified. Failure to cut the patellar facets
in the coronal plane will lead to patellar instability if too
much patellar bone is resected; if too little bone is excised,
a tightening of the patellar tendon-quadriceps tendon mechanism
results in loss of flexion.
Proximal-distal and anterior-posterior component position
have been two schools of thought concerning femoral component
positioning in these planes. Prior to the introduction of the
Universal instruments in 1978, the common way was to
first make a minimal resection of the proximal tibia followed
by a variable resection from the posterior and distal femoral
condyles to produce equal flexion and extension gaps. The Universal
instruments introduced the concept of measured resection,
whereby an amount, equal to the thickness of the prosthesis,
is resected from the distal and posterior condyles, using the
non-eroded femoral condyle as a reference (Hungerford). This
results in positioning the femoral component close to the level
of the original joint line, thus allowing the retained ligaments,
including the posterior cruciate ligament, to function in a
kinematically normal way throughout the full range of motion.
results may be obtained using the common flexion-extension gap
method as long as the prosthesis is not moved too far from the
original joint line. One pitfall that must be avoided in the
common gap method is the prevention of the free movement of
ligaments by osteophytes or scar. For example, if, after
having made the flexion gap, the extension gap is then determined
with retained posterior osteophytes (or scarred posterior capsule),
the distal femoral resection will be excessive; while the knee
will be stable in full extension, as soon as the knee flexes
a few degrees and the posterior capsule is no longer under tension,
the knee will be unstable. Within reasonable limits it is probably
acceptable to move the joint line proximally (by removing more
femoral bone distally) and anteriorly (by removing more femoral
bone posteriorly) by equal amounts, offsetting the additional
resection with the use of a thicker tibial component. Likewise,
it is probably permissible to move the joint line slightly distally
and an equal amount posteriorly, with an offsetting thinner
tibial component. It must, however, be realized that moving
the joint line proximally, but not anteriorly, will lead to
instability in extension or tightness in flexion depending upon
the thickness of the tibial component; moving the joint line
anteriorly, but not proximally, will lead to instability in
flexion or a fixed flexion contracture, again dependent upon
the choice of the thickness of the tibial component. If the
femoral component is moved excessively proximally and anteriorly,
the replaced knee will only be stable at 0° and 90° and not
in the midrange of flexion.
posterior positioning potential of the tibial component will
be very limited if the size of the tibial component has been
correctly selected. If a prosthesis is chosen which sacrifices
the posterior cruciate ligament, anterior posterior position
of the tibial component will not have much effect on knee stability.
However, when retaining the posterior cruciate, anterior malpositioning
of the tibial component will tighten the posterior cruciate,
since the tibial attachment of the PCL is moved posteriorly.
This could result in premature tightening of the posterior cruciate
ligament and limit flexion of the knee.
On the order of bone cuts
are some systems which require a specific order of bone cuts.
In general, these are systems which balance the ligaments by
creating a common gap in flexion and extension. We believe that
there are some inherent problems in using the common flexionextension
gap method. If certain precautions are utilized, this can result
in a satisfactorily aligned and balanced prosthesis. The two
precautions are: 1) the joint line must not be moved excessively
from its original location; 2) all blocks to the free movement
of the retained soft tissues must be released or removed prior
to the creation of the common gaps. This can sometimes be difficult
because access to all areas of the knee is limited prior to
making the cuts. The disadvantage of making the tibial cut first
is that posterior structures cannot be adequately exposed, particularly
the posterior cruciate attachment to the tibia. In addition,
the alignment references for the proximal tibia are not as apparent
prior to resecting the posterior femoral condyles and subluxing
the tibia anteriorly. There are few disadvantages to cutting
the femur first, which is the method we prefer. The single disadvantage
is that it does require 90° of knee flexion. In the knee which
is rigid or ankylosed, this can be difficult or impossible,
requiring that the tibial cut be made first. The advantages
of cutting the distal and posterior femur first include: 1)
all of the alignment references for all of these cuts are available
as long as the knee can be flexed to 90°; 2) with the femoral
cuts completed, exposure for the tibial cuts is greatly facilitated.
For most total knee systems there is only one configuration
of femoral component for a given size. For some systems, the
thickness of the distal and posterior aspects of the prosthesis
may vary between sizes and for other systems they remain constant.
However, if the distal and posterior joint lines are to be re-established,
it is important that the amount of bone resected from the distal
and posterior femur be equal to the dimensions of the prosthesis.
This may require choosing the correct femoral size prior to
making any of the cuts. With the original PCA prosthesis
the amount of distal and posterior resection is constant among
all of the sizes available with the variation in size being
anterior and mediallateral. This allows the distal and posterior
femoral cuts to be made prior to selecting the ultimate femoral
size, and also allows a larger size to be changed to a smaller
size without affecting the stability of the joint in extension
or flexion. The theory for the PCA system is that, if
the level of the joint line is used as a reference and recreated,
then the radius of curvature of the prosthesis will match the
radius of curvature of the natural knee, and the collateral
ligaments will function under physiologic tension throughout
the range of motion. This premise appears, in fact, to be true
for the vast majority of knees, but the final test is with the
trial reduction when collateral ligament tension is balanced
both medially and laterally, in flexion and in extension.
is a fundamental separateness between the order of the bone
cuts and the balancing of ligamentous tension. Although, in
most instances, both will take place simultaneously, they can,
in fact, be done as completely separate steps. It is important
to realize that one must not compensate for ligamentous imbalance
by selective malalignment of the prosthesis. Such malaligment
will lead to its own separate set of problems, which have already
the moderately severe arthritic knee, ligamentous balance will
be virtually automatically achieved by debriding the knee during
exposure, removing osteophytes, loose bodies, scarred synovium,
and releasing retracted capsule, as long as alignment is correct
in all of the planes. Ligamentous instability, however, can
also be imposed by individual component malalignment. Moreover,
offsetting malalignments usually produce stability in only one
degree of flexion, leaving asymmetrical ligament tightness throughout
the rest of the range of motion. Therefore, the first step,
in assuring ligamentous balance throughout a functional range
of motion, is correct individual component placement. Any residual
instability at the time of trial reduction is then a rather
straightforward procedure of tightening the loose side or releasing
the tight side.
section describing the special techniques for dealing with severe
deformity appears following the section on the standard surgical
technique. The first section of this chapter presented the rationale
for total knee arthroplasty technique with review of some of
the consequences of failure to achieve those technical goals.
Whatever system is chosen must be carefully studied and understood
along with the specific characteristics of the implant and the
nearly midline, straight skin incision, slightly towards the
medial side, avoids being directly over the patella or the tibial
tubercle. The quadriceps tendon is split at the medial one third,
central one third junction, and is carried distally, through
the medial retinacular, to the tibial tubercle (Fig. 15-17).
15-17. - The knee is approached through a
longitudinal midline skin incision, followed by a medial
para-patellar capsular incision. The quadriceps tendon is
incised longitudinally, allowing eversion and dislocation
of the patella laterally.
Cutting the distal femur
the knee at 90° flexion, the menisci and peripheral osteophytes
are removed, an intercondylar drill hole is made, anterior to
the femoral attachment of the PCL.
intramedullary alignment rod with a distal femoral cutting guide
attached is passed to the level of the isthmus. The bushing
to align the varus-valgus orientation of the cut is selected
with preoperative templates. The extramedullary guide confirms
correct alignment and can be used if the intramedullary
space is not free (THR, plate/screws, etc.) (Fig. 15-18).
fixing the distal femoral cutting block to the anterior femur,
the alignment jig must be properly rotated. Posterior condyles
are primary guides with epicondyles and trochlea as secondary
the distal femoral cutting jig flush against the prominent condyle,
the position of the cutting block will insure that the thickness
of the distal resection is equal to the distal thickness of
the prosthesis (Fig. 15-19).
N° 2 jig references off the posterior condyles. If one condyle
is defective posteriorly (rare), a space will be created equal
to the defect. The reference 3/16” drill holes will properly
align the femoral component for rotation, medial-lateral, and
anterior-posterior positions (Fig. 15-20). The posterior
condylar resection is the same for all prosthetic sizes. Size
variability adjusts at the level of the anterior resection.
N° 3 cutting block size is chosen so that the anterior cut
will not notch the anterior femur. The size of the posterior
cut is constant (Fig. 15-21).
chamfer cuts complete preparation of the femur. The posterior
chamfer cut is constant for all sizes. The anterior cut is specific
to each size (Fig. 15-22).
the femoral cuts completed, the femoral component can be tried
for fit. The proximal margin of the posterior condyle should
be marked with a curved osteotome. Failure to remove posterior
osteophytes will result in lack of full extension and may also
block full flexion (Fig. 15-23).
common error is to underresect the anterior femur, particularly
as the cut approaches the anterior cortex. The consequence will
be to cause the femoral component to flex as it approaches full
seating. This should be looked for and corrected before the
posterior bone is crushed.
the femoral cuts made, the tibia can be subluxed in front of
posterior horns of the two menisci are removed and the tibial
attachment of the posterior cruciate ligament is identified.
Residual peripheral osteophytes, particularly postero-medial,
are also removed.
tibial cutting jig controls the varus-valgus, flexion-extension
and rotational aspect of the tibial cut (Fig. 15-24 a
long fixation pin of the assembly is inserted into the middle
of the tibial plateau and the ankle clamp fits around the distal
tibia. The two points define the mechanical axis. Flexion-extension
attitude can be adjusted by moving the distal part of the assembly
forwards or backwards. The assembly should be lined up with
the midlateral longitudinal axis of the lower leg, not with
the anterior tibial crest. Rotational alignment is checked by
using the transverse axis of the tibial plateau, the position
of the tibial tubercle (slightly lateral to the midline)
and the transmalleolar axis as rotational references. Once triaxial
alignment has been assured and finally checked, the top piece
is driven down, engaging the short pin which will prevent rotation.
There remains only to determine the level of the tibial cutting
block and to secure it to the tibia with 1/8” drill pins. Once
this is done, the tibial cutting assembly is removed leaving
the cutting guide in place. Care in cutting is necessary to
avoid damage to collateral and posterior cruciate ligaments.
initial trial reduction is done on the N° 7 jig, which is the
drill guide for the final fixation holes for the tibial component
(Fig. 15-25). This jig determines the final medial-lateral,
anterior-posterior, and rotational position of the tibial component.
It is important to avoid medial overhang of the prosthesis as
this might cause painful conflict with the medial collateral
ligament. In general, rotation will be in the same orientation
as the tibia was cut. However, some rotational change is still
possible. Internal rotation of the component must be avoided.
Different degrees of rotation can be tested prior to selection
of the final orientation.
Trial reduction is done initially with the N° VII jig
which allows confirmation of the orientation of the tibial
cut and selects the position of the tibial fixation holes.
That determines medial-lateral, anterior-posterior and
rotational positions of the tibial component.
reduction may detect medial-lateral, rotational, or anterior-posterior
instability. In such cases, the first place to look is for obstacles
to the free travel of soft tissue stabilizers. Posterior condyles
and the posteromedial tibia are the first place to check for
retained osteophytes or tight capsule. It is also possible that
the distal femur was underresected. If this were so, the trial
reduction, with the tibial spacer that provided stability in
flexion, would show a fixed flexion contracture. Any fixed flexion
contracture, which is evident at the time of trial reduction,
may be either on the basis of tight soft tissue structures requiring
either resection of those things which are blocking free excursion
of those soft tissues, or release of the soft tissues. On the
other hand, the fixed flexion contracture may be indicative
of the need to recess the femoral component proximally. This
technique is described under the section “Management of severe
patellar facets are resected at the level of the attachment
of the quadriceps tendon and the retinaculae into the “equator”
of the patella. Final trial reduction includes a trial patellar
component and a tibial base plate, which allows reduction of
the extensor mechanism to check for range of motion, stability,
ligament balance and patellar tracking.
TECHNIQUES FOR DEALING WITH SEVERE DEFORMITY
1° Fixed valgus deformity
Type I valgus deformity.
- This type of deformity involves loss of bone stock from
the lateral side, usually with equal amounts of bone deficiency
from the tibia and the femur. The deformity may be passively
correctable or fixed. However, the medial ligamentous structures
must be intact and the standing X-ray will not show any opening
of the medial joint space. If a type I patient has a fixed valgus
deformity, lateral soft tissue release will allow the leg to
be passively aligned correctly while maintaining medial soft
tissue stability (Fig. 15-26 a).
Type II valgus deformity. - The elements of type
I deformity are all present, i.e. lateral bone stock loss with
or without lateral structure contracture. The criteria of demarcation
for type II deformity, however, is that the medial soft tissue
stabilizers are attenuated and elongated. On the standing film,
the medial joint line is significantly opened. In these cases,
the lateral soft tissue structure will have to be released not
only to allow the leg to be aligned, but also to allow the tibia
to be sufficiently distracted away from the femur to stabilize
the attenuated medial structures. Alternatively, the medial
structures will be reconstructed and shortened (Fig. 15-26 b).
a) Type I valgus deformity: Bone loss on the
lateral side but no medial instability.
b) Type II valgus deformity: Attenuation of the
medial soft tissue stabilizer is evident both clinically
soft tissue release
are six soft tissue structures which stabilize the lateral side
of the knee: the iliotibial band, the popliteus muscle, the
biceps muscle, the lateral head of the gastrocnemius, the lateral
collateral ligament and the posterior lateral capsule (Fig.
15-27). Four of these six stabilizers are musculotendinous complexes,
which, we believe, explains the tendency for valgus deformity
to become fixed. The lateral release is best done at the time
of trial reduction because it is only at that time that one
can adequately assess which structures require releasing. We
prefer to limit the release to those structures which are tight
rather than to simply carry out an extensive and complete release.
In most cases, complete release is not necessary. Prior to any
lateral release, it is important to make sure that all femoral
and posterolateral tibial plateau osteophytes have been removed.
The most common structure requiring release is the iliotibial
band. We prefer to Z-plasty lengthen this structure rather than
to simply transect it. The popliteus muscle can be transected,
if necessary. The lateral collateral ligament should be released
from its femoral origin as an osteo-periosteal slide.
The lateral soft tissue stabilizers and their levels of
1. Iliotibial band; 2. Parapatellar release; 3. Popliteus
tendon; 4. Fibulectomy (rarely necessary); 5. Lateral collateral
ligament; 6. Biceps femoris tendon; 7. Lateral head of gastrocnemius.
the deformity is so severe as to require lengthening of the
biceps tendon and/or the lateral head of the gastrocnemius,
it is safer to utilize a separate, posterolateral incision,
to identify and protect the peroneal nerve. In rare instances,
it may be necessary to resect the fibular head to decompress
the peroneal nerve. In most instances of severe valgus deformity,
the medial structures will be attenuated and stretched. We prefer,
in such cases, to limit the lateral release to that which allows
correction of the deformity, and then to carry out a medial
ligamentous reconstruction. In most instances, only the iliotibial
band and the posterolateral capsule will need to be released.
Further lateral decompression can be accomplished by modest
femoral shortening, which is described under fixed flexion contracture.
Femoral shortening, however, should not be considered unless
the surgeon is already committed to also carry out a medial
soft tissue advancement
procedure is only necessary for severe (type II) valgus deformities.
The median, parapatellar skin incision must be extended 5
cm distally in order to expose and reflect the proximal
half of the pes anserinus insertion. This exposes the attachment
of the superficial collateral ligament to the tibial metaphysis
(Fig. 15-28). All of the soft tissues attached to the proximal
medial tibial metaphysis are reflected posteriorly to the insertion
of the semimembranous tendon, as a single ligamentous and capsular
flap. Dissection is facilitated by having the knee in 90°
of flexion and progressively externally rotating the
a and b) The skin incision
is extended distally and the top half of the pes anserinus
tendons are reflected distally to expose the superficial
medial collateral ligament.
1. Pes tendon group; 2. Medial collateral ligament.
re-attachment of the capsular ligamentous flaps is performed
only after the components are permanently in place. The tibial
component thickness that is selected should stabilize the posterior
cruciate ligament and the lateral ligamentous structures-throughout
the range of motion. With the knee in 10-15° of flexion and
the tibia in neutral rotation, the capsular ligamentous flap
is pulled distally and slightly anteriorly. It is fixed to the
medial tibial metaphysis by staples, supplemented by heavy sutures
inserted through and tied over bone (Fig. 15-29). It is important
to be careful not to selectively tighten the anterior portion
of the medial capsule or closure of the median parapatellar
incision will be difficult or impossible. To protect against
this, it is helpful to place holding sutures at the proximal
and distal margins on the median side of the patella to make
sure that the capsule can be closed. The pes anserinus is then
re-attached to cover the soft tissue repair. Standard postoperative
care consists in routine physical therapy with active and active-assisted
range of motion excretes, and ambulation in a posterior splint
to protect the repair.
15-29. - The medial capsular
ligamentous structures are pulled distally and slightly
anteriorly where they are re-attached to the tibia.
2. Medial collateral ligament; 3. Staples; 4. Prostheses.
Fixed varus deformity
resection alone on the tibia will allow the axial deformity to
be corrected, but will exacerbate the relative laxity on the lateral
side. Theoretically, the same possibility exists as for a fixed
valgus deformity. However, the lateral side is dynamically stabilized
since four of the six structures stabilizing the lateral side
are attached to muscles and mild to even moderate lateral instability
is well tolerated. Therefore, release of the medial structures
usually suffices to both correct the deformity and balance the
soft tissue stabilizers. Since the medial release must include
the superficial medial collateral ligament, the entire medial
side of the tibia needs to be exposed; all osteophytes are removed
and the fibres of the deep medial collateral ligament are sharply
detached from the medial metaphysis 2.5 cm distal to the joint
line. This degree of release will be sufficient for the vast majority
more extensive medial release involves exposure and elevation
of the medial ligamentous capsule in a manner identical to that
described under medial soft tissue advancement. It is not, however,
always necessary to reflect the pes anserinus since the exposure
can be done blindly with a periosteal elevator. For a varus
deformity, the medial stabilizers are recessed while they were
advanced for a severe valgus deformity.
need for lateral soft tissue advancement is extremely rare and
will not be described in detail. Basically, the fibular head,
with the attached lateral collateral ligament and biceps tendon
is mobilized after transecting the fibular neck. It is then
drawn distally to assess the appropriate length of the fibular
neck that must be resected to restore tightness in the lateral
structures; the fibular head is then fixed to the shaft, using
an intramedullary, cancellous bone screw.
Fixed flexion contracture
first step in treating severe fixed contracture is to minimize
the fixed flexion contracture preoperatively. This includes
serial casting, bracing, stretching and physical therapy. The
vast majority of fixed flexion contractures can be reduced by
at least 50% through one or a combination of these modalities.
Any fixed flexion contracture of more than 30° should be considered
for an attempted preoperative reduction.
any severe fixed flexion contracture can be treated by a generous
resection of the distal femur and proximal tibia. However, aside
from violating the basic principles of removing as little bone
as is absolutely necessary, overzealous bone resection is unsatisfactory
for two reasons. Firstly, the knee which extends only on the
basis of bone resection will only be stable in extension, since
the stability in extension will only be provided by the posterior
capsule. As soon as the knee flexes a few degrees, the posterior
capsule will relax and the knee will be completely unstable.
Bone resection alone, to correct fixed flexion contracture,
can only be used with completely intrinsicly stabilized knee
components and is not satisfactory for standard unconstrained
osteophytes and capsule
of the most common causes of a persistent fixed flexion contracture
after the standard bone cuts is the presence of significant
posterior femoral osteophytes (Fig. 15-30). The osteophytes
deform the posterior capsule causing the capsule to be prematurely
tight prior to full knee extension. Resection of all posterior
marginal osteophytes is essential to correct a fixed flexion
Posterior femoral osteophytes are visible on the lateral
preoperative X-ray. They distract the posterior capsule
in extension leading to flexion contractures.
the time of trial reduction, if the knee does not extend fully,
the cause of this lack of extension must be determined. If the
collateral ligaments become tight prior to the knee extending
fully, then the distal femur can be shortened. If, however,
the lack of full extension is caused by premature tightening
of the posterior capsule, then the capsule can be divided under
direct vision with the knee at 90° of flexion.
capsular layer should be identified and incised away from the
midline to avoid damage to the posterior tibial or popliteal
neurovascular structures. Dissection with a curved clamp can
separate the capsule from the gastrocnemius muscle allowing
its transverse division under direct vision. In rare instances,
the origins of the heads of the gastrocnemius muscle may be
stripped from the femur with a periosteal elevator.
the distal femur
the Universal total knee instrumentation system, it is
easy to resect additional bone from the distal femur. The 1/8”
pins, which were used to fix the N° 1B primary distal femoral
cutting jig, are reinserted into the distal femur. The 5B jig
is placed upon these drill pins and the distal femur is recut.
This resects exactly 2 mm of additional femur. If additional
femoral resection is necessary, the axillary N° 5 jig can be
inserted onto the drill pins and another 2 mm of distal femur
can be resected. Additional distal femoral resection will have
to be followed by recutting the chamfer cuts of the anterior
femoral cut, but not the posterior cut. Distal femoral resection
recesses the femoral component proximally only, thereby producing
additional space for extension, but, since the femoral component
stays in the same anterior-posterior plane, stability in flexion
is not affected.
EXTENSOR MECHANISM PROBLEMS
series report a two to five percent incidence of significant
extensor mechanism problems. Complications include patellar
tendon rupture, quadriceps tendon rupture, patellar fracture,
patellar subluxation, and dislocation. Many aspects of total
knee replacements, other than those directly involved with the
extensor mechanism, impact on the functioning of the quadriceps
mechanism. This begins with exposure in the tight knee with
limited flexion preoperatively. Excessive traction or leverage
on the extensor mechanism must be avoided. If sufficient exposure
cannot be achieved through the standard median patellar approach,
then a reflection of the tibial tubercle may be necessary to
facilitate exposure. Excessive retraction, particularly with
retractors with long leverage handles, may result either in
patellar fracture or patellar tendon avulsion. The latter complication
is to be avoided at all costs.
of the patella is a multifactorial problem and can be caused
by malposition of either the femoral or the tibial component.
Internal rotation of the femoral component displaces the trochlear
groove medially and increases the likelihood of patellar dislocation.
Underresection of the anterior femur with the implantation of
an unnecessarily large femoral component pushes the extensor
mechanism anteriorly, tightens the lateral retinaculum and predisposes
to lateral patellar subluxation. Internal rotation of the tibial
component lateralizes the tibial tubercle, thereby increasing
the quadriceps angle and predisposes to patellar subluxation.
Underresecting the patella, also, displaces the patella anteriorly
tightening the lateral retinaculum and predisposing to dislocation.
using a dome patellar button, the medial margin of the button
must be coated with the medial margin of the cut patella. The
normal patella is broader in the medial-lateral plane than in
the proximal-distal plane. The patellar button, which does not
overhang proximally or distally, will not fully cover the patella
medial-laterally. Since the center of the dome is symmetric
and since the central ridge on the normal patella is asymmetrically
displaced towards the medial side, placing the dome symmetrically
on the cut surface of the patella functionally lateralizes the
central ridge of the dome compared to the original anatomic
position. This increases the Q angle and predisposes to subluxation-dislocation.
Therefore, in order for the dome to be concentrically located
in the prosthetic patello-femoral groove, the patellar button
should be slightly displaced medially.
older people may heal tendinous soft tissues more slowly than
younger patients. Dissolvable sutures placed in the retinacular
and quadriceps tendon repair may lose their strength before
these tissues have sufficiently healed. We, therefore, prefer
to use nonabsorbable sutures in the central third of the extensor
mechanism repair. Attention to all of these details will minimize
the likelihood of patello-femoral problems. We do not believe
that it is necessary to do routine lateral releases. However,
during the trial reduction, if there is any tendency of the
patella to sublux while no pressure is applied to the patella
to keep it located, a lateral release should be carried out.
GREENBERG R.L., KENNA R.V., HUNGERFORD D.S., KRACKOW K.A.
- Instrumentation for total knee arthroplasty. In:
HUNGERFORD D.S., KRACKOW K.A., KENNA RVTotal knee
arthroplasty’: A comprehensive approach. 35-70. Williams
and Wilkins, Baltimore, 1984.
D.S., KRACKOW K., KENNA RV - The porous-coated anatomic total
knee system. Orthop. Clin. North. Am., 13, 103-122,
D.S., KRACKOW K.A., KENNA RV - Total knee arthroplastv:
A comprehensive approach. Williams and Wilkins, Baltimore,
J.A. - Surgery of the knee. Churchill Livingstone,
New York, 1984.
J.N., TRJA A.J., SCOTT W.N. - The total condylar knee prosthesis:
The first five years. C/in. Orthop., 145, 68, 1979.
I.A. - The physiology of the joints, Vol. II. 74-75.
Churchill Livingstone, New York, 1970
K.A. - Management of fixed deformity at total knee arthroplasty:
General principles. In: HUNGERFORD D.S., KRACKOW K.A.,
KENNA RVTotal knee arthroplastv: A comprehensive approach,
163-166. Williams and Wilkins, Baltimore. 1984.
K.A. - Management of fixed deformity at total knee arthroplasty:
Fixed flexion contracture. In: HUNGERFORD D.S., KRACKOW
K.A., KENNA RVTotal knee arthroplastv: A comprehensive
approach, 193-201. Williams and Wilkins, Baltimore, 1984.
R.S. - Management of fixed deformity at total knee arthroplasty:
Fixed varus deformity. In: HUNGERFORD D.S., KRACKOW
K.A., KENNA RVTotal knee arthroplastv: A comprehensive
approach, 179-192. Williams and Wilkins, Baltimore. 1984.
J.R., BASSETT L.W., HANKER G.J. - Radiographic analysis of
axial alignment of the lower extremities. J. Bone Joint
Surg., 69A, 745-749, 1987.
JR., THOMAS R.J., FREEMAN M.A.R. -ICLH replacement of the
knee: 1977 and 1978. Clin. Orthop.. 145, 47, 1979.
R.D., THORNHILL T.S. - Press fit condylar total knee replacement.
Technique Orthop., 4, 41-58, 1987.
JA, MATSEN F.A., GARBINI IL.. LARSON RV, LARSEN
J.M. - Total knee arthroplasty: Functional effects
of tibial resection level. Transactions of 32nd Orthopaedic
Research Society. 11, 263, 1986.
Revision knee arthroplasty
for revision total knee arthroplasty include joint sepsis, component
loosening, and ligamentous instability. Joint infection is diagnosed
by arthrocentesis and culture. Once an infection has been diagnosed,
treatment may be removal of components and a staged reimplantation.
Sequential radiographic demonstration of component migration
is proof of septic or aseptic component loosening. Careful history
and physical examination are usually sufficient to diagnose
significant ligamentous instability. Pain alone in the absence
of any definable cause is not an indication for revision knee
arthroplasty. It is incumbent upon the orthopaedist to clearly
identify a surgically correctable cause of the pain prior to
recommending revision knee arthroplasty.
careful preoperative plan is essential and includes evaluation
of previous surgical incisions and the need for special implants
or bone graft material and special instruments that will be
necessary for surgery. Previous skin incisions should be used
whenever possible. Parallel incisions and V-shaped incisions
should be avoided. Consultation with a plastic surgeon is sometimes
helpful to plan the incision. Once the knee is open, it may
be necessary to increase exposure. This may be done either proximally
or distally. Proximally, a Coonse-Adams patellar turndown, or
a modification as described by Scott (Fig. 15-31), may be performed.
The theoretical disadvantage of these maneuvers is that they
may devascularize the patella and the patellar flap. An alternative
is to perform a tibial tubercle osteotomy (Fig. 15-32). Potential
complications relate to tibial tubercle osteosynthesis; tendon
ruptures, tibial fractures, and avulsion of the tubercle are
other complications of this maneuver. Although both maneuvers
have potential complications, they are sometimes necessary since
forcibly flexing the knee, to increase exposure, may result
in patellar tendon avulsion.
of the components
of the components that are not loose may be a difficult problem.
It is essential to free all bone cement or bone-metal interfaces
prior to applying a significant distraction force to the implant.
Flexible osteotomes, which are much thinner than rigid osteotomes,
are essential. By applying excessive distraction force to the
implant, through a specialized extraction tool, the surgeon
runs a significant risk of removing excessive amounts of bone.
This is particularly true with components that were applied
in a cementless fashion.
Implants and Bone Grafting
attempting to reconstruct the knee joint, it is necessary to
consider several fundamental rules of primary knee replacement
and to supplement them with several other principles. In primary
total knee arthroplasty, the three fundamental principles are
the creation of accurate overall knee alignment, the attainment
of accurate bone cuts, and the achievement of correct ligamentous
balance. In revision knee arthroplasty, the additional fundamental
principle is the reconstitution of an anatomically accurate
joint line which is necessary to achieve the proper function
of the patient’s remaining ligaments and to avoid producing
either a patella alta or a patella baja.
some cases, this may require significant bone grafting of large
defects. In other situations, special prostheses with augmentation
may be necessary. Revision femoral implants are available that
have augmentations both distally and posteriorly (Fig. 15-33).
Augmented prostheses must be available in various sizes.
These implants can be used in conjunction with bone grafting
of smaller defects on the distal femur.
bone loss in the proximal tibia may require implants with medial
and/or lateral plateau build-up to restore tibial stock. If
a shell of bone remains on which the implant can be placed,
these special implants may be used in conjunction with various
bone grafts to fill smaller defects within the shaft of the
tibia itself. The use of massive tibial bone allografts on which
the tibial component is supported has not been shown to be a
anterior-posterior instability due to ligamentous inadequacy
may be present. This is particularly true when the posterior
cruciate ligament and the posterior capsular structures are
severely weakened. This situation may require the use of a nonhinged,
stabilized prosthesis (Fig. 15-34). Several types of knee revision
systems are available that incorporate these options. The selection
of the correct one for each patient should be part of the surgeon’s
Distally and posteriorly augmented femoral components
are available in either (a) one-piece units or
(b) modular units
15-34. - A tibial post articulates with the
femoral housing to provide anterior-posterior stability.
balance must be achieved in any successful knee arthroplasty.
Releasing the tight side is the traditional and preferred way
of achieving correct balance (Figs. 15-35 and 15-36). Rarely,
it may also be necessary to advance the loose side. With extreme
lateral instability, the lateral colateral ligament must be
exposed to the fibular head (Fig. 15-37). A section of fibular
neck may be resected and the fibular head reattached with a
screw to the fibular shaft. This has the effect of tightening
the fibular collateral ligament. When performing this maneuver,
the peroneal nerve must be carefully isolated and protected.
The need for lateral ligament advancement must be determined
after the medial side has been maximally released and trial
reduction with a plastic spacer has been performed.
medial ligament laxity, the lateral side is maximally released
and trial reduction is performed. If significant medial laxity
still remains, the medial capsular structures are transected
at the level of the pes anserinus. With the appropriate trial
implants in place, the medial structures are advanced distally
and fixed with staples or screws (Fig. 15-38).
is an important part of revision knee replacement. Because of
the uniqueness and complexity of each case, therapy must be
adjusted to accommodate individual variations. Patients who
have huge angular deformities and significant ligamentous modifications
may require postoperative bracing and may be poor candidates
for continuous passive motion. Similarly, patients with distal
tubercle osteotomies or patellar tendon turndowns may require
other restrictions. It is incumbent upon the surgeon to communicate
these specifics to the therapist.
summary, revision total knee replacement is a difficult problem
that requires careful preoperative planning to be certain that
the proper equipment is present at the time of surgery and to
minimize the actual surgical time. Great care must be taken
to choose the correct skin incision and create accurate overall
axial alignment. The use of specialized revision knee systems
as well as judicious use of bone grafts are essential to reconstitute
an accurate joint line and maximize the chance of the best possible
K., ADAMS J.D. - A new operative approach to the knee joint.
Surg. Gvneco!. Obstet., 77. 344-347. 1943.
D.S., KRACKOW K.A., KENNA RV - Total knee arthrop!asty:
A comprehensive approach. Williams and Wilkins, Baltimore,
J.N. - Surgery of the knee, 635-644. Churchill
Livingstone, Edinburgh, 1984.
M.A, HUNGERFORD D.S., KRACKOW K.A., LENNOX D.W. - Revision
of septic total knee replacement. Clin. Orthop. Rel. Res.,
236, 103-110, 1988.
RD, SILISKI J.M. - The use of a modified VT quadriceps-plasty
during total knee replacement to gain exposure and improve
flexion in the ankylosed knee. Orthopedics. 8, 45-48,
Distraction arthroplasty of the knee
aim of a distraction arthroplasty of the knee is to provide
motion to an ankylosed knee without implant interposition.
principles are the following: extensive arthrolysis, complete
freeing of the quadriceps, contoured bony resections, a distraction
apparatus that will temporarily stabilize the pseudarthrosis
while maintaining the bony surfaces apart and permit early mobilization.
operation is usually indicated for fibrous or bony ankylosis
following resistant infections in young patients or in patients
where the use of a prosthesis is not indicated.
of the patient
patient is supine on an ordinary table and a tourniquet is preferable.
arthrolysis and freeing of the quadriceps are achieved by medial
and lateral incisions.
extensive lateral approach will permit complete dissection of
the quadriceps from the anterolateral and anteromedial aspects
of the entire femur.
bony resection is usually performed via the medial incision
using osteotomes to free the patella from the distal femur (Fig.
15-39) in order to dislocate the extensor mechanism laterally.
Whenever possible, the level of the femoral and tibial resections
are at the original joint line; if the latter is completely
obliterated, the level of the patellar tendon insertion will
serve as a reference point.
tibial resection is usually performed first (Fig. 15-40). A
straight osteotome is used to expose cancellous
bone at both tibial plateaus which are contoured slightly concave
in all directions to provide some stability, preserving, whenever
possible, a central, sagittal ridge at the level of the former
resection is achieved with curved osteotomes and a Putti, curved
gouge for the posterior femoral condyles, attempting to achieve
an outline that resembles the original, distal femur (Fig. 15-41).
Bony ankylosis of the knee involving the femur, tibia and
patella. Patello-femoral osteotomy via a medial arthrotomy.
Tibio-femoral ostotomies. Insert: amount of bony resection
Modelling of the neoarticular surfaces.
to twelve millimeters of bone are usually resected to obtain
a satisfactory range of motion. While the remains of the collateral
ligamentous attachment to the tibia are spared, the cruciate
ligaments are almost always sacrificed.
is then usually preferable to release the tourniquet so as to
free the quadriceps (in particular the vastus lateralis from
the intertrochanteric line and the rectus femoris from the anterior,
inferior iliac spine).
passive knee mobilization must be obtained at the expense of
instability which will be subsequently
controlled by the distractor.
of the changing instant centre of rotation in the knee, the
apparatus has two centres of rotation (Fig.
surgical steps are the following (Fig. 15-43): - temporarily
identify the two centres of rotation by pins in the distal femur.
Two transverse pins are first inserted in the anterior and posterior
portions of the femoral condyles, corresponding to the site
of axes of rotation in flexion and extension;
15-42. Schematic axes of tibio-femoral rotation.
15-43. - Application of the
distractor is then constructed around these two axes;
the femoral component is fixed to the femur via two pins inserted
in the distal femoral metaphysis;
other pins are inserted in the tibial epiphysis, and side plates
of appropriate length are then selected;
the two pins corresponding to the future axes of rotation are
then removed and the entire distractor is interconnected. Final
adjustments (Fig. 15-44) in the length of the distractor plates
are then made as the knee is passively mobilized, ensuring that
there is always a 10 mm gap between the femur and the tibia
during the full range of motion.
Attachment of side plates to maintain distraction during
full, passive mobilization.
re-adjustments of the apparatus are usually necessary.
weight-bearing is permitted on the second week.
of the distractor after 75 days is followed by gradual weight-bearing.
is usually necessary for at least six months.
Arthrodesis of the knee
are numerous techniques to achieve a knee arthrodesis. The currently
available techniques differ principally in terms of fixation
and may be described as: 1) limited internal fixation and casting;
2) intramedullary rod fixation; 3) double bone plating; 4) external
fixation. Each of these approaches has its advantages and disadvantages
as delineated in table 15-I.
internal fixation and cast
Possibly smaller surgical exposure
from pin tract problems
- Poor stability and healing in failed total knee salvage
- Foreign body in case of possible infection
- Poor stability in obese leg
- Excellent varus-valgus and flexion-extension stability,
less rotational stability
- Freedom from pin tract problems
- Technically difficult
- Require special rod
- Potential spread of infection
- questionable rotational stability
- Freedom from external fixator and pin problems
- Questionable stability with poor bone stock
- Relative contraindication in infection
- Larger surgical exposure
- Potential stability even with poor bone stock
- No permanent implant
- Potential pin tract problems
- Bulky, cumbersome and expensive apparatus
plating and intramedullary techniques should not be used when
infection is present or suspected. In cases of primary fusion
with good bone stock, limited fixation plus casting, or external
fixation has been selected. In primary fusions with infection,
or in total knee arthroplasty salvage situations, with or without
infection, external fixation is preferable.
Infection. - Planning
is outlined in table 15-II. When treating a failed total knee
arthroplasty, infection should always be considered, and ruled
in or out, by aspiration, biopsy, and gallium scanning, so that
appropriate antibiotic therapy can be instituted. When infection
is present and fusion has been elected, it may be performed
as a single stage procedure, or as a two stage procedure.
15-II. - PREOPERATIVE PLANNING
aspiration, biopsy, Gallium 67 scanning
alignment: 5-7° valgus tibiofemoral angle
alignment: normal intermalleolar axis
flexion angle: 5-20°; consider shortening and ankle
grafts: allograft, local, iliac crest
total knee arthroplasty instrumentation for controlled
distal femoral and proximal tibial cut.
Instrumentation. — Adequate instrumentation must be available
for component removal in total knee arthroplasty salvage situations,
especially if metalbacked tibial trays have been used. Exact
knowledge of the inner surface geometry of the implant to be removed
is mandatory. It is helpful to have previously discarded,
representative, components present in the operating theater to
refer to. Total knee replacement instrumentation may also be used
to make well aligned, flat distal femoral and proximal tibial
Grafting. — Consideration must be given to bone grafting,
especially in the presence of large defects.
Alignment. — Position and alignment of the arthrodesis
can be described in terms of axial alignment, i.e. tibio-femoral
angle, rotational alignment, and flexion angle. While no recognized
clinical disadvantage is seen with minimal aberration in the
tibio-femoral angle, seek to preserve a normal
tibio-femoral angle of 5-7° valgus. Rotational alignment
must be achieved so that the foot points normally during gait.
recommendations exist regarding the proper flexion angle at
the arthrodesis site. Recommendations between 50 150
are common as minimal knee flexion may help when rising from
a seated position and facilitate hip extension in a more normal
fashion. Additionally, one must recognize that 1.5
to 2 cm of relative shortening at the operative side is
necessary for the foot to clear objects on the floor and to
facilitate swing of the fused leg. However, one must guard against
additional point to consider when planning flexion at the knee
fusion site is the impact of fixed knee flexion on the position
and kinematics of the ankle. For a patient to stand with a plantigrade
foot on an extremity with the knee fused requires that the ankle
dorsiflexe. Furthermore, as the patient steps forward on the
opposite foot, ankle dorsiflexion on the operative side must
Rotational alignment. — Prior to surgical exposure,
it is desirable to identify reference points for both femoral
and tibial rotational alignment.
- In cases of primary knee fusion without pre-existing femoral
malrotation, the axis formed by the posterior femoral condyles
can be used to define neutral rotation (Fig. 15-45).
femoral malrotation exists, this should be assessed preoperatively
whenever possible, so that appropriate compensation can be made.
A CT scan of both femurs can be used to establish malrotation
of the operative side in comparison to the normal rotation of
the contralateral extremity (Fig. 15-46).
Tibia. — The apparent rotation of the
tibia should be evaluated in terms of general appearance, the
orientation of the foot, and the position of the intramalleolar
axis (Fig. 15-47 a and b).
The axes of femoral and tibial rotation are identified before
the joint surfaces are excised, so that rotational alignment of
the entire lower extremity is correct (Figs. 15-46 and 15-47).
Exposure. - Preexisting incisions are used when possible.
If none are present, or if only a transverse one is present,
a midline, longitudinal exposure is used (Fig. 15-48).
capsular incision is made longitudinally in the quadriceps tendon,
then extended in a routine medial parapatellar fashion (Fig.
of the joint surfaces is not difficult unless massive intra-articular
adhesions are present. Mobilization of tissues anteromedially
and anterolaterally over the femur is necessary if flexion of
the knee is to be achieved.
one is dealing with an ankylosed knee in good position for fusion,
the distal femur and proximal tibial joint surfaces are excised
parallel to one another and the fixation is applied, holding
the knee in the desired position.
commonly, extensive exposure is necessary. The patellar tendon
is elevated from the tibial tuberosity if necessary, and dissection
is extended between the quadriceps mechanism and the anteromedial
as well as the anterolateral aspects of the femur to allow knee
flexion. Thickened, scarred tissue is removed to facilitate
eversion of the patella.
90° of flexion has been achieved, a 1/8” Steinmann pin is placed
transversely across the distal femur, oriented in neutral femoral
rotation (Fig. 15-50) and at 90° to the vertical axis (Fig.
15-51) or, if possible, at an angle, relative to the femoral
shaft that corresponds to the orientation (varus-valgus) of
the planned distal femoral cut (Fig. 15-51). Utilizing the Universal
Total Knee Instruments the distal femoral cut is
at a 9° valgus angle (81° complementary angle), when the tibial
cut is at an angle of 3° varus, for a final tibio-femoral angle
of 6° valgus (Fig. 15-52). With a perpendicular tibial
cut, a distal femoral cut of approximately 6° valgus (84° complementary
angle) will be necessary.
1/8” tibial rotation pin is placed in neutral rotation at an
angle corresponding to the angle of the tibial
cut (either 3° varus or perpendicular, according to whether
the femoral cut is to be 9° valgus or 6° valgus) (Fig. 15-53).
When a cemented tibial component blocks the placement of
this pin, the pin is inserted after component removal.
the indication for fusion is a failed total knee arthroplasty,
the femoral and tibial components are removed sequentially being
careful to preserve as much bone as possible. Total knee arthroplasty
instruments may be used to align and facilitate the performance
of accurate, flat distal femoral and proximal tibial bone cuts.
The femoral instrument is placed in neutral rotation according
to the femoral rotational pin and is adjusted to be neutral
or in the desired degree of flexion for the femoral cut. A flat,
well aligned distal resection is made with a reciprocating saw
a transverse proximal tibial cut is made with total knee replacement
instruments positioned in neutral rotation and with the desired
degree of anterior to posterior slope so that when the femoral
and tibial surfaces are approximated, the desired total amount
of flexion will be achieved (Fig. 15-54).
joint excision space is examined as the surfaces are temporarily
apposed to assess the accuracy of contact and fit (Fig. 15-55).
After total knee arthroplasty, especially after revision
total knee arthroplasty, it is frequently necessary to elevate
soft tissues from the posteromedial, posterolateral, and posterior
tibial cortex to allow the cut surfaces of the femur and tibia
to approximate (Fig. 15-56 a and b).
maneuver is necessary due to a blocking effect of the bulging
soft tissue sleeve. The peripheral displacement of this sleeve
is impeded by its attachment to the cortices at the resection
is next directed to the patella, which may either be: 1) excised
and discarded; 2) excised and morcelized as bone graft; 3) left
attached and incorporated into the fusion area. The patella
should not be left free as patellofemoral symptoms can develop.
It is possible to leave the patella attached to the lateral
soft tissues and to fix it to the fusion site as a vascularized
bone graft utilizing a lag screw (Fig. 15-57). However, this
technique requires pulling the patella distally and can make
wound closure more difficult.
Limited internal fixation plus cast. - In the case of
primary fusion with good bone stock and a very “castable” lower
extremity, the femoral and tibial surfaces are apposed, being
certain to align the femoral and tibial rotational pins parallel
to one another. The bones are internally fixed with lag screws.
Bone grafting is performed if desired; the patella is handled
according to the surgeon’s preference and the wound is closed.
A cylinder cast is carefully applied.
External fixation. - Before inserting the external fixator
pins, the femoral and tibial rotational pins are removed and
replaced transcutaneously so that wound edge approximation is
possible with these rotational pins in place. It is convenient
to substitute 7/64” Steinmann pins at this stage as they will
easily pass through the previously drilled pin tracks.
avoid tension at the skin puncture sites of the external fixator
pins, the wound edges are temporarily approximated with towel
clips, before repositioning the femoral and tibial rotation
transfixion pins are generally placed from medial to lateral
for maximal control on the side of the femoral artery. Tibial
pins are generally placed from lateral to medial similarly to
have maximum control with respect to the peroneal nerve. In
cases of severe bone loss, where conical bone ends exist at
the distal femur and/or proximal tibia, the transfixion pins
are situated farther away from the arthrodesis site to provide
greater stability. In extreme cases, safe positioning of proximal,
femoral pins may require exposure of the femoral artery.
to lateral transfixion pins provide excellent stability against
varus-valgus stress, but poor stability against flexion and
extension and anterior “half pins” may be used. At least two
femoral and two tibial half pins are placed through the anterior
and posterior cortices. A lateral intraoperative X-ray is taken
to be certain that these half pins do not protrude beyond the
external fixator frame is assembled taking care to keep the
femoral and tibial sets of transfixion pins parallel to one
another in the rotational axis, while the femoral and tibial
bone surfaces are approximated. The bone cuts themselves guide
the amount of flexion and the varus-valgus alignment. The parallel
transfixion pins assure proper rotation of the tibia with respect
to the femur and correct varus-valgus alignment.
for patellar cortico-cancellous bone, the author does not routinely
add a bone graft in noninfected cases. However, substantial
pieces of iliac crest can be used peripherally to establish
cortical continuity or improve mechanical stability. The use
of large autogenous bone grafts into vacuous tibial and/or femoral
spaces should be avoided. When central cancellous bone is largely
or totally absent, morsalized bone grafts are also placed peripherally
Peripheral bone grafting in the presence of central bony
1. Femur; 2. Defect; 3. Bone graft peripherally; 4.
patella is dealt with last, either removing it as bone graft
material, removing and discarding it, or fixing it to the distal
femur over the level of fusion.
have been successfully closed primarily in the presence of infection.
Closure is performed after thorough debridment with complete
removal of all components, cement, and old suture material.
Where radio-opaque cement has been implanted, an intraoperative
X-ray is taken to document that the cement has been completly
closure, except in cases of primary fusion, may be difficult.
This is due to the tissue bulging effect mentioned earlier.
Minimal, buried suture material is used only at the capsular
level. Absorbable chromic or polyglycolic acid materials are
employed. Meticulous skin closure with interrupted nylon is
performed, utilizing retention sutures since no subcutaneous
or subderrnal sutures are inserted.
routine, noninfected cases, prophylactic intravenous antibiotics,
i.e. penicillinase resistant penicillins or cephalosporins,
are continued for 48 hours. In cases which are presumably infected
after failed total knee arthroplasties, antibiotics are continued
longer until the peroperative cultures show no growth.
the operative culture reveals infection, or when dealing with
a known infection, parenteral antibiotics are continued for
three to six weeks according to the severity of infection, and
the “nature” of the infected organism. Oral antibiotics are
continued for another three months.
care is routine, with once or twice daily cleansing of pin sites,
utilizing hydrogen peroxide or saline, followed by the application
of bacitracin antibiotic ointment. Iodine containing solutions
or ointments should be avoided. Local pin tract infections are
usually successfully treated by short courses of oral antibiotics.
postoperative weight-bearing status depends upon the type of
fixation as well as the bone quality and stability at the fusion
site. Patients with limited internal fixation and casts are
not allowed to bear weight for one to three months, followed
by progressive weight-bearing for the next two to three months
with cast removal at 4-6 months once union is demonstrated.
conceptually, a simple and basic orthopaedic procedure, knee
arthrodesis may be quite difficult due to exposure problems,
implant removal, preparation of a satisfactory fusion site and
achievement of stable fixation in excellent position.