Fusion for Irretrievably Failed Total Knee Replacement
D. Wiedel, M.D.
the past 30 years, the increasing success of total knee arthroplasty
has gradually replaced arthrodesis as the procedure of choice
in most conditions causing severe joint destruction. Instead
of a primary procedure, arthrodesis is now considered a salvage
procedure relegated to cases where total knee replacement may
he contraindicated, e.g. sepsis, neuropathic joint, and youth,
or for an irretrievably failed total knee replacement (3,8,9).
all causes of total knee replacement failure, infection is the
most common indication for knee fusion (3,4,9). In a small number
of cases, the infected arthroplasty may he salvaged by debridement
and long-term antibiotics, either retaining the original prosthesis,
or removal, and later performing a second prosthetic arthroplasty.
The chances of succeeding with this technique may be very slim,
at best. The success reported for salvage of infected total
hip replacements has not been duplicated for the infected total
of total knee replacement on the basis of aseptic loosening,
instability, fractures, and prosthetic wear or breakage are
usually managed satisfactorily by a revision arthroplasty. The
purpose of this chapter is to discuss the indications and techniques
for arthrodesis after a failed total knee, including some of
the difficulties and pitfalls as well as alternatives to fusion.
this chapter addresses "irretrievably failed" total
knee replacements which by definition preclude further consideration
of total knee arthroplasty, when considering knee fusion in
the context of failed arthroplasty, it is appropriate first
to consider failed total knee replacements in general.
the orthopaedist faces a failed total knee replacement, the
most common considerations are first revision surgery and second
salvage fusion. In planning for such a situation, great consideration
must be given not only the upcoming operation, but also to that
procedure which would follow if the NEXT one failed also.
an eye toward fusion as the end stage operation, the basic requirements
for satisfactory fusion must be kept in mind. First, adequate
bone stock must be present in order for there to be satisfactory
likelihood of healing. Secondly, excessive shortening, as a
result of repeated resection of distal femur and proximal tibia,
should be avoided to the extent possible. While most modern
prostheses used for primary total knee replacement fulfill the
general conditions of minimal bone resection, many of these
prostheses used for revision surgery with bulky stems with or
without housings do not fulfill these requirements.
basic concern is that leading a patient down a path of multiple
unsuccessful arthroplasties may well leave him with an unsalvageable
limb and inevitable amputation when earlier more prudent acceptance
of knee fusion would have preserved lower limb function. The
success of obtaining a fusion after total knee replacement differs
significantly when comparing failed nonconstrained prostheses
(80%) with failed hinges (35%)(3). Success rates as low as 21%
have been reported for attempted fusion upon removal of hinged
factors have to be considered when choosing between revision
arthroplasty or arthrodesis: the patient's age, medical status,
activity level, the basic disease process and the condition
of other joints, particularly the hips and contralateral knee.
We are not particularly concerned about revision arthroplasty
that will still allow preservation of sufficient bone stock
for subsequent arthrodesis. However, revision arthroplasty that
would require the use of a bulky stemmed prosthesis which, if
failed, would not allow a salvage procedure short of probable
amputation, must be considered only under dire circumstances.
Furthermore, we are not, at this time, considering the failed,
infected total knee replacement.
this in mind, the younger and more active patient with a normal
life expectancy and with reasonably good neighboring joints
should be considered more strongly for an arthrodesis. On the
other band, if the patient is quite elderly and debilitated,
an arthrodesis may be impractical, making revision arthroplasty
the procedure of choice. Similarly, patients with rheumatoid
arthritis and multiple joint involvement tolerate knee fusions
patient with a contralateral knee fusion presents a particularly
difficult problem. If one were to fuse the ipsilateral knee,
a situation may be created whereby the patient completely loses
the ability to transfer from sitting to standing positions.
This situation most likely will exist in the patient with polyarthropathy
where the upper extremities are so severely involved that they
cannot be used to assist in transfer. If faced with this situation,
every effort should be made to avoid an arthrodesis.
arthroplasty should be considered as an alternative to knee
fusion which should be considered when faced with the patient
who is very inactive and severely disabled. Consideration of
this alternative may be especially appropriate if the patient
has multiple joint involvement.
arthroplasty can provide some flexion, allowing a patient to
sit in a more comfortable and convenient position as well as
providing extension for standing. Although the resection arthroplasty
alone may not be stable enough for weightbearing, external brace
support can be an acceptable method of controlling instability
for the purpose of walking.
the patient finds the resection arthroplasty unsatisfactory
because of instability or pain, an arthrodesis can still be
attempted. Furthermore, delaying an arthrodesis may be advantageous
if infection is present and not well controlled or if the patient
is not mentally prepared for a knee fusion.
the main indications for performing an arthrodesis after an
irretrievably failed total knee replacement is to provide a
stable, pain-free extremity particularly in the ambulatory patient.
have been many operative techniques described for arthrodesis
of the knee joint (2, 5, 6, 11-15, 17, 18). Methods that lend
themselves to usage after total knee replacement failure are
compression arthrodesis, either external or internal, and intramedullary
compression arthrodesis remains the most commonly used procedure
and has been reportedly more successful than other methods (3,
19). The success of arthrodesis depends mainly on two factors:
apposition of large congruent trabecular surfaces and rigid
fixation. The former, no doubt, is the most important, which
accounts for the success of primary arthrodesis when little,
if any, fixation is used. Unfortunately, this situation rarely
exists after a failed total knee replacement. Therefore, rigid
fixation becomes even more important.
(A) infected total knee arthroplasty. (B) Twelve weeks
after removal of prosthesis and application of external
compression device. (C) Fusion at 16 weeks.
(A) Infected stemmed prosthesis. (B) Failed fusion after
removal of prosthesis and attempted external compression
patterns of femoral and tibial surfaces remaining after preparation
for different types of prostheses varies significantly (10).
Resurfacing prostheses without large pegs or stems will leave
the greatest surface area, (Fig. 18.1, A-C), while the bulky
prostheses with large central stems or pegs substantially diminish
the remaining area (Fig. 18.2, A and B).
factors further reducing this area include osteoporosis and
subchondral cysts, anchoring holes drilled for cement fixation,
and further erosions of bone at the bone cement interface in
loosened prostheses. All of these circumstances clearly emphasize
the importance of choosing a primary or revision prosthesis
which requires minimal bone resection to optimize the chances
of performing a successful salvage procedure, whether it be
a revision prosthetic arthroplasty or arthrodesis.
situations may exist which require special attention and modification
of arthrodesis techniques: severe osteoporosis and bone loss.
Both of these situations create a particular problem in gaining
rigid fixation: osteoporosis, because of the difficulty in gaining
rigid bone purchase of the fixation device, and bone loss, because
of the residual small, irregular bony surfaces. Obtaining rigid
fixation in all planes is even more critical in these situations
than when the bone is of good quality and when large congruent
surfaces are present.
Standard quadralateral external fixation device.
and B) Two types of external fixation ion devices with
addition of anterior pin placement.
conventional compression device, using single pin above and
below the fusion site, does not provide adequate stability
in the AP plane for most cases of total knee replacement failure.
Even multiple pin placement, using the standard quadralateral
frames (Fig. 18.3) will not adequately control anteroposterior
(AP) motion when there has been significant bone loss. Further
pin placement anteriorly in the femur and tibia will help
stabilize this plane of motion (Fig. 18.4, A and B).
fixation devices do have their undesirable features, however.
They are large, cumbersome, and frequently heavy. The multiple
pin hole arrangements in osteoporotic bone may invite fracture.
Pin tract infections are fairly common, and these devices are
initially quite expensive. Despite this substantial list of
negative features properly applied external fixation provides
good stability at the fusion site and serious complications
among the list above are quite rare.
for knee arthrodesis.
compression arthrodesis, using double-plating techniques, is
an alternative method of securing rigid internal fixation (Fig.
18.5). This method maybe specifically indicated where external
skeletal compression fixators are undesirable. Osgood, in 1913,
and Lucas and Murray, in 1961, published their techniques of
double-plating for immobilization of the knee (15, 17). Scranton,
in 1980, further modified the technique by using compression
plating. He also reported on the use of this technique for the
failed total knee replacement (18).
fixation, using double-plating, does have the advantage of not
requiring external support devices and eliminating the problems
associated with percutaneous pins. The technique is, however,
technically very demanding. Accurate bending of the plates to
conform to the femoral and tibial contours is critical. Obtaining
the appropriate fusion also has to be accurate because, once
the plates are secured, there is no way of changing the position
short of replacing the plates. Here the use of external fixation
systems has an advantage in that position changes can be made
by adjusting the external fixation device.
nail fixation is another alternative to consider for immobilization
of the knee in an attempt to gain fusion of the knee after failed
total knee replacement. It may be most useful when severe osteoporosis
makes screw or pin fixation impractical. Intramedullary nail
fixation does have the disadvantage of not allowing a choice
of knee fusion position, and it may not provide rigid stabilization,
particularly with regard to rotation. The presence of an ipsilateral
hip arthroplasty would necessarily preclude the use of this
preparation of the bone ends for arthrodesis after a failed
total knee replacement deserves special attention. This aspect
of the procedure demands surgical experience and skills that
will allow the surgeon to modify conventional techniques and
improvise when necessary. Unexpected findings make such appropriate
modifications quite frequently necessary.
preparing the femur and tibia for arthrodesis, some basic principles
should be followed:
Bone Stock. Special care should be taken in removing
the prosthesis and cement so that bone is not inadvertently
removed. Remove only that bone which is necessary to obtain
good contact surfaces and proper alignment. If infection is
present, debride all granulation tissue and devitalized tissue,
but do not attempt to resect bone solely for the purpose of
eradicating the infection.
Congruent Trabecular Surfaces. Whenever possible, large
areas of trabecular bone should be fashioned for congruent fitting
with the opposing surface. This may be no more than a peripheral
rim or bridging surfaces.
Inherent Stability. Irregular and different sized surfaces
may have to be opposed. If this situation exists, an attempt
should be made to interlock the irregularities to gain stability
and increase the contact surfaces. When dealing with two surfaces
of unequal size, inserting one into the other like a press-fit
can provide a way of gaining stability and surface contact.
This technique is particularly useful when attempting a resectional
cases of significant bone loss preventing suitable opposing
surfaces, bone grafting maybe considered. The patella may be
available; however, the best bone graft for filling a void as
well as providing osteogenesis is probably iliac bone.
position of fusion must also be considered when preparing the
bone. The position must be determined preoperatively, based
upon the individual patient's needs. The AP alignment should
match that of the patient's other knee, if normal, and will
usually be in slight valgus. The Universal alignment instruments,
used for total knee replacement, make excellent guides for establishing
correct AP alignment.
position of flexion generally is best at 10-15°. This position
is particularly critical if there is bilateral involvement.
The patient with bilateral fusions functions best with the maximum
allowable practical flexion, probably up to 20°(16). If
the contralateral knee is less involved and the patient remains
ambulatory, the fusion should be in more extension so as to
provide a more functional position from the standpoint of walking
rather than sitting. Also, if shortening is a problem, full
extension maybe advantageous to maintain as much length as possible.
some shortening is advantageous for a knee fusion to allow for
an easier swing phase, in salvage fusions for failed total knee
replacement, unacceptable shortening may occur, particularly
from failed binge prostheses. The amount of acceptable shortening
must be determined with each patient. Obviously, any amount
of shortening can be corrected by shoe lifts or prostheses,
but this may be impractical or unacceptable because of shoe
size, weight, and appearance. The other aspect of too much softening
is the inability to obtain fusion. This is well documented in
reports by Arden (1), DeBurge (7), and Hagemann et at. (9).
grafting to make up for bone less, causing unacceptable shortening,
has marked limitations. The relative indications here would
be the situation where preservation of a stable, functional
limb was necessary because of young age and a demanding activity
level. The slow replacement of a graft bridging a large gap
would necessarily require prolonged immobilization and would
most certainly not be practical in an elderly or severely disabled
patient. In the face of marked bone loss or minimal trabecular
bone contact surfaces, electrically induced osteogenesis may
be of benefit with or without bone grafting.
of the knee for irretrievably failed total knee replacement
may very well become a more frequently performed procedure as
the number of patients with total knee replacements, the length
of follow-up, and the number of revisions increase.
type of prostheses for primary and revision arthroplasties must
be carefully selected, keeping in mind that the success of fusion
depends, to a large degree, on the type of prosthesis implanted.
The minimally constrained resurfacing types of prostheses without
large stems or pegs allow for apposition of large trabecular
surfaces and a fusion rate approaching that of a primary arthrodesis;
whereas, the large, bulky prostheses with long stems, causing
excessive methaphyseal bone loss, are associated with a significantly
lower fusion rate.
compression arthrodesis is the technique of choice in the majority
of cases. In the presence of infection, this method clearly
is preferred over internal fixation.
surgical technique of fusion following failed total knee replacement
is difficult and demanding. Careful removal of the prosthesis
and cement, preservation of bone stock and creation of large
contact surfaces, increase the chances of a successful fusion.
arthroplasty may be an acceptable alternative in selected cases.
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