In this study, all patients underwent the same staged procedure. After the
removal of implants, thorough soft-tissue débridement, and removal of
necrotic bone, antibiotic-loaded polymethylmethacrylate spacers were prepared
and inserted. Provided that there was no evidence of recurrent infection,
arthrodesis was carried out as the second stage of the procedure eight to
fourteen weeks later.
The procedure is carried out with the patient lying supine on a radiolucent
table. The entire limb is prepared and is draped free in order to allow access
from the gluteal region down to the ankle joint. Access to the knee is
obtained through one of the previously utilized anterior approaches. Ligament
and capsular attachments are released from the distal part of the femur and
the proximal part of the tibia in order to mobilize the bone ends. All foreign
materials such as cement or metal implants are removed. Thorough soft-tissue
débridement is then carried out, and necrotic, nonbleeding bone is
resected as well. Débridement of the medullary canal is also performed
and is of paramount importance in infected cases.
Provided that there is no clinical or laboratory evidence of infection at
that stage and that the bone ends are free of necrotic bone and soft-tissue
attachments, preparation of congruent viable contact surfaces between the
distal part of the femur and the proximal part of the tibia is carried out. A
pair of matched convex-to-concave reamers are used to prepare the tibial and
femoral surfaces. This technique creates a ball-and-socket configuration that
provides large contact areas of viable bleeding bone
(Figs. 1-A, 1-B, and 1-C),
improves stability, and maintains congruency after the insertion of a curved
nail (Figs. 2-A and 2-B). The
concave reamer is used to fashion the distal part of the femoral diaphysis
into a conical shape, and the convex reamer of the same size is employed to
prepare a matched cavity on the tibial plateau
(Figs. 3-A and 3-B). The reamer
size is chosen to preserve as much of the intact tibial cortex as possible.
Reaming has to be carried out until all necrotic bone is removed, but
excessive reaming must be avoided since it will increase the size discrepancy
between the osseous ends of the femur and tibia.
Reaming of the medullary canal of the tibia over a guidewire is then
performed through the knee to its maximal diameter. A 3 to 4-cm lateral
incision starting 1 to 2 cm proximal to the tip of the greater trochanter is
then made, and an awl is used to prepare the entrance hole through the
trochanteric fossa. Reaming of the femoral canal over a guidewire can be
carried out either antegrade through the lateral approach or in a retrograde
fashion through the knee. We prefer retrograde reaming in order to minimize
injury to the gluteus muscles. Reaming of the femur is carried out to the
diameter of the largest reamer that was used for the tibia, and an
intramedullary nail with a diameter of 1.0 to 1.5 mm less than the diameter of
the largest reamer that was used is chosen. The lower limb then is held in
extension with the knee reduced in the desired position, and a long guidewire
is inserted through the trochanteric fossa all of the way to the distal part
of the tibia in order to determine the appropriate length of the nail. A long
curved nail with an 18° radius in the sagittal plane is then inserted
under fluoroscopic control and is locked distally with two cross-locking
screws. Finally, to ensure maximal osseous apposition and compression, the
nail is hammered in a reverse direction from the top and then is statically
locked proximally (Fig.
3-C).
CRITICAL CONCEPTSINDICATIONS:Failure of total knee replacement in the presence of infection:
Although there are no clear-cut indications for arthrodesis following failure
of a knee arthroplasty due to infection, medically compromised patients with
comorbidities such as immunosuppression, diabetes mellitus, obesity,
alcoholism, and smoking are at increased risk for recurrence of infection
after two-stage total knee
revision2,15,16.
Rupture of the extensor mechanism in an infected environment might be treated
better with arthrodesis rather than a two-stage procedure combined with a
major attempt to reconstruct the extensor mechanism. A poor soft-tissue
envelope due to skin necrosis or extensive scarring due to multiple
operations, the presence of an infected allograft, and infection with
virulent, antibiotic-resistant bacteria are also factors that substantially
increase the risk of failure of revision arthroplasty following a deep
infection17.
Finally, arthrodesis of the knee should be considered after recurrence of an
infection, especially in an older patient with poor general health. Multiple
operations in the presence of infection not only are associated with the risk
of recurrence but also can lead to poor functional results and residual pain.
Although the decision to proceed with an arthrodesis is very difficult, the
surgeon must keep in mind that a successful arthrodesis can provide a painless
functional limb and decrease the risk of recurrent infection. A careful
evaluation of the patient's expectations and demands, his or her general
health, and the number of previous operations and their effect on the bone
stock and soft tissues around the knee should be considered and extensively
discussed with the patient when an arthrodesis is planned.Failed total knee arthroplasty with no sign of infection: Failure
of a total knee arthroplasty related to mechanical problems is generally
better managed with a revision total knee arthroplasty. Arthrodesis should be
considered only for medically compromised patients who have a high risk of
infection or have had multiple revisions and a very poor functional result.
Finally, rupture of the extensor mechanism in a knee that has been treated
with multiple operations may be an indication for arthrodesis in selected
patients.CONTRAINDICATIONS:Contralateral above-the-knee amputationContralateral knee or hip arthrodesisIpsilateral advanced degenerative changes of the hipIpsilateral total hip replacementIpsilateral ankle osteoarthritisExtensive bone loss affecting the tibial and/or femoral metaphysisFracture of the diaphysis of the tibia or femurPITFALLS:When a knee has undergone many previous operations, the surgical approach
might be difficult and associated with a risk of skin necrosis. In infected
cases, draining sinuses should be excised en bloc. Wound closure might be
difficult, and the surgeon should be prepared to use a local muscle flap if
needed.Preparation of the bone ends with the convex-to-concave reamers should be
carried out with great caution. Appropriately sized reamers should be selected
in order to preserve as much bone as possible. On the tibial side, preparation
of a deep cavity must be avoided since it will increase the leg length
discrepancy. We suggest that tibial reaming be stopped as soon as an extensive
bleeding surface of cancellous bone that articulates well with the femoral
side has been prepared.The diameter of the nail that is selected is based on the maximum diameter
that the tibia can accommodate and is usually inadequate to fill the femoral
medullary canal. This is a potential cause of micromovement and instability
and therefore we choose to statically lock the intramedullary nail.
CRITICAL CONCEPTS
INDICATIONS:
Failure of total knee replacement in the presence of infection:
Although there are no clear-cut indications for arthrodesis following failure
of a knee arthroplasty due to infection, medically compromised patients with
comorbidities such as immunosuppression, diabetes mellitus, obesity,
alcoholism, and smoking are at increased risk for recurrence of infection
after two-stage total knee
revision2,15,16.
Rupture of the extensor mechanism in an infected environment might be treated
better with arthrodesis rather than a two-stage procedure combined with a
major attempt to reconstruct the extensor mechanism. A poor soft-tissue
envelope due to skin necrosis or extensive scarring due to multiple
operations, the presence of an infected allograft, and infection with
virulent, antibiotic-resistant bacteria are also factors that substantially
increase the risk of failure of revision arthroplasty following a deep
infection17.
Finally, arthrodesis of the knee should be considered after recurrence of an
infection, especially in an older patient with poor general health. Multiple
operations in the presence of infection not only are associated with the risk
of recurrence but also can lead to poor functional results and residual pain.
Although the decision to proceed with an arthrodesis is very difficult, the
surgeon must keep in mind that a successful arthrodesis can provide a painless
functional limb and decrease the risk of recurrent infection. A careful
evaluation of the patient's expectations and demands, his or her general
health, and the number of previous operations and their effect on the bone
stock and soft tissues around the knee should be considered and extensively
discussed with the patient when an arthrodesis is planned.
Failed total knee arthroplasty with no sign of infection: Failure
of a total knee arthroplasty related to mechanical problems is generally
better managed with a revision total knee arthroplasty. Arthrodesis should be
considered only for medically compromised patients who have a high risk of
infection or have had multiple revisions and a very poor functional result.
Finally, rupture of the extensor mechanism in a knee that has been treated
with multiple operations may be an indication for arthrodesis in selected
patients.
CONTRAINDICATIONS:
Contralateral above-the-knee amputationContralateral knee or hip arthrodesisIpsilateral advanced degenerative changes of the hipIpsilateral total hip replacementIpsilateral ankle osteoarthritisExtensive bone loss affecting the tibial and/or femoral metaphysisFracture of the diaphysis of the tibia or femur
Contralateral above-the-knee amputation
Contralateral knee or hip arthrodesis
Ipsilateral advanced degenerative changes of the hip
Ipsilateral total hip replacement
Ipsilateral ankle osteoarthritis
Extensive bone loss affecting the tibial and/or femoral metaphysis
Fracture of the diaphysis of the tibia or femur
PITFALLS:
When a knee has undergone many previous operations, the surgical approach
might be difficult and associated with a risk of skin necrosis. In infected
cases, draining sinuses should be excised en bloc. Wound closure might be
difficult, and the surgeon should be prepared to use a local muscle flap if
needed.Preparation of the bone ends with the convex-to-concave reamers should be
carried out with great caution. Appropriately sized reamers should be selected
in order to preserve as much bone as possible. On the tibial side, preparation
of a deep cavity must be avoided since it will increase the leg length
discrepancy. We suggest that tibial reaming be stopped as soon as an extensive
bleeding surface of cancellous bone that articulates well with the femoral
side has been prepared.The diameter of the nail that is selected is based on the maximum diameter
that the tibia can accommodate and is usually inadequate to fill the femoral
medullary canal. This is a potential cause of micromovement and instability
and therefore we choose to statically lock the intramedullary nail.
When a knee has undergone many previous operations, the surgical approach
might be difficult and associated with a risk of skin necrosis. In infected
cases, draining sinuses should be excised en bloc. Wound closure might be
difficult, and the surgeon should be prepared to use a local muscle flap if
needed.
Preparation of the bone ends with the convex-to-concave reamers should be
carried out with great caution. Appropriately sized reamers should be selected
in order to preserve as much bone as possible. On the tibial side, preparation
of a deep cavity must be avoided since it will increase the leg length
discrepancy. We suggest that tibial reaming be stopped as soon as an extensive
bleeding surface of cancellous bone that articulates well with the femoral
side has been prepared.
The diameter of the nail that is selected is based on the maximum diameter
that the tibia can accommodate and is usually inadequate to fill the femoral
medullary canal. This is a potential cause of micromovement and instability
and therefore we choose to statically lock the intramedullary nail.
In the first five patients in our series, parallel tibial and femoral bone
cuts were used to achieve maximum contact of viable bleeding cancellous bone.
An effort was made to make the bone cuts parallel, with no or minimal gaps.
Because we used a curved nail with an 18° radius of curvature in the
sagittal plane, it was technically difficult to achieve full contact at the
arthrodesis site (Fig. 4). In
the following seven patients, convex-to-concave reaming as described above
improved congruency and simplified the preparation of the bone ends.
All of the arthrodeses in our series were performed in patients in whom a
total knee arthroplasty had failed because of infection. As mentioned, all
patients underwent the same staged procedure, with preparation and insertion
of antibiotic-loaded polymethyl-methacrylate spacers after the removal of
implants, thorough soft-tissue débridement, and removal of infected
necrotic bone. We used 6 g of tobramycin and 6 g of vancomycin per 40 g of
polymethylmethacrylate.
In three patients, débridement and exchange of spacers had to be
carried out twice because of recurrent infection. On the basis of the results
of cultures and sensitivity testing, appropriate intravenous antibiotics were
administered for four to six weeks. This was followed by an observation period
of four to eight weeks.
AUTHOR UPDATE:There have been no major changes in the surgical technique since
publication of the original article.
AUTHOR UPDATE:
There have been no major changes in the surgical technique since
publication of the original article.
Knee arthrodesis was not performed until clinical and laboratory data
indicated that the infection had been eradicated. These data included a normal
C-reactive protein level and a normal erythrocyte sedimentation rate after the
discontinuation of intravenous antibiotics as well as evidence that the wound
had healed and was quiescent.
At the time of the proposed arthrodesis, the spacers were removed.
Débridement of the soft tissue and the medullary canals was performed
and the bone-end cuts were freshened, followed by thorough irrigation with
pulsed lavage. Tissue samples were obtained from multiple sites (including the
medullary canal of both the tibia and the femur) for frozen-section analysis.
If the polymorphonuclear leukocyte count was less than ten per high-power
field14, knee
arthrodesis was carried out.
Two patients with excessive scarring due to multiple skin incisions or
previous sinus tracts had a local flap transfer for wound coverage at the time
of the arthrodesis. In the remaining ten patients, wound closure over a drain
was carried out in a routine fashion.
All patients were allowed to walk with an aid on the second postoperative
day, with partial weight-bearing as tolerated.