- Discussion:
- IM may be most reliable technique for achieving union;
- w/ TKR infection, IM fusion needs to be performed in a staged fasion with removal of components
and control of infection before fusion is attempted;
-
contra indications:
- active infection:
- presence of active infection because of risk of infection spreading into medullary
canals of the femur and tibia;
- deformity of the femoral or tibial shaft:
- clearly a nail will not pass around an angulatory deformity;
- PreOp Planning:
- x-rays include a full-length AP radiograph of lower extremity and lateral radiographs of
the femur and tibia;
- radiographic markers are used to define radiographic magnification;
- long intramedullary nail that extends from greater trochanter to distal part of the tibia
is used for a knee arthrodesis;
- diameter of nail depends on diameter of IM canal of tibia, which generally
has a smaller diameter than the femur;
- when a large difference exists between the diameter of the femur and
tibia, it will be difficult to achieve a tight interference fit;
- this may require application of cast postop;
- nails of several diameters should be available at the operation in case the preoperative
templating of the radiographs was incorrect;
- TKR Implant Removal:
- preparation of the osseous bed;
- preparation of the bone ends should expose vascular bone, provide bone apposition, correct
limb alignment, and preserve as much bone stock as possible;
- when bone cuts are being performed, extramedullary TKR cutting jigs can be used to achieve
alignment and bone apposition;
- bone resection should be limited to one to two mm of bone from the femur and tibia;
- proximal part of tibia is be cut 1st to provide cut that is 90 deg to coronal plane and
has the desired degree of posterior slope in the sagittal plane;
- bone ends should be vascular, stable, apposed, & in correct flexion and valgus;
- establish a tibiofemoral angle of 0 degrees to allow passage of intramedullary nail;
- Nail Selection and Insertion Strategy:
-
full length antegrade nails:
- refers to nails inserted antegrade from the piriformis fossa down across the knee and into the tibia;
- due to the disadvantages of this type of implant is less often used;
- advantages:
- these nails provide maximum stability;
- AP bow of the femur in the sagittal plane will allow three-point fixation of the nail in the femur;
- disadvantages:
- entery thru the piriformis fossa and IM femoral reaming down to the knee joint causes
significant bleeding which cannot be diminished by a tourniquet;
- implant removal is especially difficult if there is implant failure;
- reaming across localized infected tissue may cause extensive femoral and tibial osteomyelitis;
- tibial-femoral mismatch requires use of a smaller nail which decreases stability;
-
short nails inserted thru the knee joint:
- have become more popular due to ease of insertion and high union rate (over 90%);
- nail is driven retrograde into the femoral canal, and then is backed out down into the
tibial medullary canal;
- advantages:
- piriformis fossa remains intact and therefore blood loss can be minimized w/ a tourniquet;
- femoral - tibial mismatch is not a problem;
- implant failure is unlikely due to the smaller nail length;
- Technical Pearls:
- ream the tibia first to determine the maximal nail size (in most cases the femur will accomodate
a larger nail than the tibia);
- care must be taken to prevent distraction of the arthrodesis site during insertion of the
nail into the tibia;
- above knee cast is used for six weeks to provide rotational stability;
- progressive weight-bearing to patient tolerance is begun while cast is still in place;
- Bone Grafting:
- posterior bone graft is placed before IM nail is inserted;
- should be performed at time of arthrodesis for cases w/ extensive bone loss;
- in presence of bone loss, cancellous bone-grafting, by incr surface
available for bone apposition, can improve the chances of success;
- bone graft should be placed about periphery of the arthrodesis site to allow
revascularization from surrounding soft tissues;
- intramedullary circulation of the bone is usually compromised by prior implant and cement, the
- Complications:
- complications inherent in intramedullary nailing include nail breakage,
nail migration, and bone fracture.
- complications associated with intramedullary nailing for arthrodesis
have been reported in 40 to 55 per cent of cases;
Arthrodesis of the knee with an intramedullary nail.
Knee arthrodesis using combined intramedullary rod and plate fixation.
Intramedullary Arthrodesis of the Knee after Failed Total Knee Arthroplasty.
Intramedullary fixation for arthrodesis of the knee after infected total knee arthroplasty.
Knee arthrodesis using a short locked intramedullary nail.
A new technique.
SL Cheng and AE Gross.
Am J. Knee Surg. Vol 8. p 56-59. 1995.
Arthrodesis of the knee with a modular titanium intramedullary nail.
JS Arroyo et al.
JBJS. Vol 79-A. Jan 1997. p 26-35.
Arthrodesis with a short Huckstep nail as a salvage procedure for failed total knee arthroplasty.
K Lai MD et al.
JBJS Vol 80-A. No 3. March
1998. p 380.
