Management of Fractures Around Total Knee Replacement
Jerome D. Wiedel, M.D.
Total Knee Arthroplasty: A Comprehensive Approach
Editors: Hungerford, David S., Krackow, Kenneth A. and Kenna,
about replacement components are becoming more widely recognized
as a complication following total knee arthroplasty. The incidence
seems to be increasing as the number of patients and the length
of follow-up increase. Several authors have reported on this complication
(1-4, 6-8, 10, 11) with two series recently describing some of
the causes and methods of treatment (5, 9).
around a total knee replacement may occur at three different
sites: distal femur, proximal tibia, and patella. In this chapter
fractures around total knee replacements are discussed under
each of these anatomic sites emphasizing etiologic factors,
mechanisms of injury, methods of treatment, and complications.
mechanism of injury causing the distal femur fracture invariably
involves minor trauma, usually tripping or slipping and falling
to the floor. Such minimal force as twisting the leg, in either
a standing or recumbent position, has caused this fracture.
reviewing reported series and our own cases, several factors
may account for the ability of such trivial trauma to cause
these fractures. Osteoporosis is probably the most consistent
finding. Furthermore, many of these patients preoperatively
were either nonambulatory or minimally so, and once an initially
successful total knee replacement has been performed they have
become active. However, because of unsteadiness and residual
weakness, they are more susceptible to injury.
reviewing the types of prostheses associated with fractures,
it was apparent that prostheses which required more bone resection,
particularly removal of the posterior femoral cortex, had a
greater risk for this complication.
type of distal femoral fractures following total knee replacement
are quite similar to the recognized standard classification:
1) distal shaft, 2) supracondylar, and 3) condylar. These will
be discussed separately since the management and complications
may differ significantly. It should be noted that this material
represents a review of the author's own series of cases, a number
of which have at sometime been treated by different attending
Femoral Shaft Fractures
distal femoral shaft fracture may occur clearly proximal to
the femoral component (Fig. 15.1), seemingly unrelated to the
prothesis or at the proximal extent of a long stemmed prosthesis
(Fig. 15.2). Fractures occurring about a stemmed prosthesis
are likely to be oblique, indicating a torsional stress-induced
fracture. A fixed-hinged prosthesis may further contribute to
the likelihood of this type of fracture. With no axial rotation
possible within the prosthesis, increased torsional stress is
undoubtedly generated within adjacent bone.
of these fractures was by closed means; initially, skeletal
traction and balanced suspension followed by external support
in the form of a brace or splint. All the fractures united in
satisfactory position. Three patients' postinjury status remained
unchanged from their preinjury status. One patient (St. Georg
prosthesis) remained in a wheelchair after fracture healing
with a limited range of motion (65-90°).
femoral shaft above a nonstemmed femoral component.
group of fractures represents the most common type following
total knee replacement. It is the most commonly reported type
and, in the author's series, accounted for 11 of the 17 fractures.
Most of these fractures are oblique with varying degrees of
comminution and occasionally with condylar involvement. The
fracture deformity, when present, was interestingly the opposite
of that typically described for a supracondylar fracture (Fig.
15.3). This finding may be the result of a different mechanism
of injury in that these patients usually fall onto their knees,
forcing the distal fragment with the prosthesis posteriorly.
Furthermore, the relative muscular weakness in these patients
results in minimal, if any, deforming force with which to produce
the typical deformity.
of the fractures were closed except for one which had a small
anterior laceration at the fraction level. This fracture initially
had an open debridement followed by traction. Eight other fractures
were also initially managed by closed means, either in traction
or plaster immobilization. The two remaining fractures in this
group were initially managed open. One had an open reduction
and blade plate fixation. The prosthesis present was a Marmor
bicompartmental replacement. The other case was a short oblique
fracture in a patient with a Spherocentric prosthesis which
was revised to a long stem Guepar prosthesis (Fig. 15.4, A and
prostheses present in this group of fractures included: Spherocentric,
5; UCI, 3; total condylar, 1; Marmor, 1; and Walldius, 1.
results of treatment included three delayed unions and one nonunion.
One delayed union occurred in the patient previously described
who had an open fracture above a total condylar prosthesis.
An open procedure with blade plate fixation was accomplished
8 weeks after the fracture, and the fracture ultimately healed.
other two cases of delayed union occurred in patients with Spherocentric
prostheses. One eventually healed after 6 months in plaster,
and the other one was revised to a long stem prosthesis after
4 months of closed management failed to gain union.
case of nonunion occurred in a short oblique fracture above
a Spherocentric prosthesis. After 4 months of closed management,
union was not evident (Fig. 15.5A); therefore, revision to a
long stem Spherocentric prosthesis was performed. Fifteen months
later nonunion persisted (Fig. 15.5B), at which time bone graft
and an osteostimulator were inserted (Fig. 15.5C). Thirty-two
months after fracture the patient died of causes unrelated to
the total knee replacement. The final status of union was never
determined. The patient was able to transfer and ambulate minimally,
using a walker.
15.2. Oblique distal
femoral shaft fracture at the level of a stemmed femoral component.
occurred in two cases, one with a Marmor prosthesis and one
with a Spherocentric. Of the remaining seven fractures, one
patient died before completion of healing, and six healed in
satisfactory position (Fig. 15.6, A and B).
Spherocentric unit was the single most common prosthesis involved
with fractures in this series (5), and all were of the supracondylar
type. In these 5 cases different circumstances led to different
solutions. One patient had a loosened tibial component prior
to the fracture. One patient underwent primary revision to a
long stem prosthesis, and one had a revision to a long stem
prosthesis after the fracture was considered a delayed union
4 months following closed management. A fourth case went on
to a malunion and loosening of the femoral component (Fig. 15.7)
and the fifth developed a nonunion (previously described).
review of the supracondylar fractures it is quite apparent that
significant complications can occur. There is not one form of
management that will give uniformly good results. Each case
has to be individually considered on the basis of the patient's
status (medical, ambulatory), the characteristics of the fracture
(degree of comminution, deformity), and the type of prosthesis
fracture amenable to internal fixation which would not interfere
with the prosthesis may be the ideal management to avoid prolonged
bed rest. However, many of these fractures are to comminuted
for internal fixation, and the prosthesis may be of the type
that would not allow use of conventional internal fixation devices.
An alternative in this case would be to revise the prosthesis,
using a longer stemmed device to stabilize the fracture.
supracondylar fractures occurring around long stemmed prostheses
have internal fixation already in place and may be amenable
to closed management with early ambulation, using minimal external
standard short stemmed Spherocentric prosthesis presents a particularly
difficult management problem. The type of treatment- whether
open, in which case it would probably have to be a revision
of the prosthesis, or closed-must be considered on an individual
basis. In situations where the surgeon has strong preference
for a Spherocentric unit, review of our experience suggests
that use of a longer stemmed unit, rather than the standard
short stemmed device, may lessen the chance of subsequent supracondylar
demonstrates typical deformity of a supracondylar femur fracture
and a radiograph demonstrates the opposite deformity in a
supracondylar femur fracture above a Spherocentric prosthesis.
15.4. (A) Displaced oblique supracondylar femur
fracture above a Spherocentric prosthesis. (B) Twelve months
after revision to a long stemmed femoral component.
fractures occur only in the presence of nonstemmed prostheses.
In the author's series, two cases were encountered; one in a
geometric and the other a total condylar prosthesis (Figs. 15.8
and 15.9). Both presented with posteriorly displaced and angulated
distal fragments and prostheses. In spite of traction and attempts
at closed manipulative reduction under anesthesia, satisfactory
reduction could not be obtained. Open reduction and internal
fixation were not felt feasible. Therefore, the deformity was
allowed to persist, managing both cases closed. These fractures
healed but in unsatisfactory positions (Fig. 15.10, A and B).
The geometric prosthesis shown in Figure 15.10A was later revised
to a Spherocentric unit. At surgery the femoral component was
noted to be stable; however, the tibial component was loose.
other case has an unsatisfactory range of motion (0-50°),
and this patient requires two crutches and a brace for walking.
15.5. (A) Nonunion of supracondylar femur fracture
above a Spherocentric prosthesis. (B) Fifteen months after
revision nonunion persisted. (C) After bone graft and osteostimulator
15.6. (A) Comminuted supracondylar femur
fracture above a UCI prosthesis. (B) Five years later, fracture
united, range of motion 0-100°.
Malunion of supracondylar femur fracture with loosened Spherocentric
15.8. Condylar fracture
above a geometric prosthesis.
15.9. Condylar fracture above a total condylar
15.10. (A) Malunion of condylar fracture shown
in Figure 15.8. (B) Malunion of condylar fracture shown in
following conclusions were suggested after review of distal
femur fractures around total knee replacement:
femoral shaft fractures are the most amenable to closed management
and have the lowest complication rate.
and condylar fractures have a significant complication rate.
type of prosthesis will influence the management of supracondylar
deformity in supracondylar and condylar fractures is frequently
the opposite of the typical deformity observed in similar
fractures without prostheses.
healing does not seem to be impaired by the presence of prothesis
treatment is recommended unless the reduction is unsatisfactory.
In this case either open reduction and internal fixation should
be done, providing the fracture is amenable to fixation, or
primary prosthesis revision to a long stemmed femoral component
may be performed.
tibial fractures following total knee replacement occurring
as a result of trauma are rare. In the author's review of over
800 cases which produced 17 cases of distal femur fractures,
no case of traumatically induced tibial fracture was encountered.
The type of proximal tibial fracture encountered following total
knee replacement is typically a stress fracture (Fig. 15.11).
These fractures are observed in cases where axial malalignment
has produced abnormally high, eccentric loads on either the
lateral or medial tibial plateau. Medial tibial plateau fractures
with associated varus malalignment are the most commonly observed
stress fractures (2, 9).
loosened tibial component has been observed in all reported
cases and has been present in all cases reviewed by the author.
The tibial plateau fractures associated with a loosened tibial
component and axial malalignment are best managed by revision
arthoplasty. It is critical to reestablish the normal physiologic
alignment of 5-10° valgus to prevent this complication.
nonoperative candidates, external bracing using a hinged brace
may provide some relief of patient's symptoms and aid in their
15.11. Fracture of medial tibal plateau. Tibial
component is loose and genu sarus deformitynoted.
fractures following total knee replacement are rare indeed and
have only become a concern since prosthetic patellar replacement
has become a routine part of total knee procedures. The cases
reviewed by the author have occurred as a result of a fall or
simply upon getting up from a sitting position.
factors are osteoporosis and a weakened patella as a result
of resection for patellar replacement. Technical errors in removing
too touch bone or malpositioning the prothesis may also contribute
to the causes of patellar fracture.
management of these fractures is essentially the same as for
patellar fractures without associated prosthetic arthoplasty.
If the fracture is minimally displaced or nondisplaced, conservative
treatment is recommended. Significantly displaced fractures
with disruption of the extensor mechanism should be operated
upon if possible. The actual procedure performed will depend
upon the condition of the bone.
the fracture is amenable to fixation and the prosthesis is not
loose, simply fixing the fracture should be considered. However,
if the prosthesis is loose, a decision must be made as to whether
the fracture can be fixed, followed by reinsertion of a prosthesis,
or whether patellectomy may not be the best solution (Fig. 15.12).
15.12. Displaced patella fracture treated with
about the knee following total knee replacement will undoubtedly
increase as the number of patients with total knee replacement
and the length of follow-up increases.
main emphasis should be on prevention. This can be accomplished,
at least in part, by proper selection of patients, proper selection
of the prosthesis, and performing technically accurate procedures.
the face of fracture, each case must be carefully evaluated
and the best method of treatment selected on an individual basis.
Factors to be considered in addition to the patient's medical
and ambulatory status are the type of fracture and the type
of prosthesis already in place.
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