- all foreign material must be removed from the knee;
- retained frags of cement can act as nidus for residual infection;
- infected granulation tissue & scar tissue should be excised to provide healthy vascularized soft tissue surrounding the knee.
- number of debridements needed before wound closure depends on surgeon's ability to remove all infected material and on whether or not
bone-grafting is to be performed.
- at least two separate debridement procedures should be performed after implant removal, and there should be at least one negative culture,
before bone-grafting is done;
- removal of components & primary arthrodesis should be reserved for cases in which reimplantation is not considered possible & there
is minimal arthritic involvement of adjacent joints.
- IV ATB:
- intravenous antibiotics for 6 weeks after complete removal of an Infected Total Knee prosthesis;
- Knee Flexion:
- optimum position for knee arthrodesis is slight flexion;
- w/ minimum bone loss:
- 10-20 deg of flexion allows foot to clear ground during swing phase of gait w/o circumduction of hip;
- there should be slight valgus and 10 deg of external rotation;
- w/ marked bone loss:
- in instances of marked bone loss, position closer to full extension maintains as much length as possible.
- in no instance should knee be placed in > 20 degrees of flexion;
- Bone Apposition:
- most important factor for success of arthrodesis is bone apposition;
- there must be vascular cancellous bone apposition.
- resection of 1-2 mm of bone from distal aspect of femur & proximal aspect of tibia exposes vascular bone;
- whenever possible, the interdigitation of bone ends should be done to improve stability and bone apposition.
- large, hinged implants & implants w/ intramedullary stems necessitate sacrifice of more bone, and less bone is left for apposition than
is left with resurfacing designs;
- similarly, the knee with multiple revisions has less chance of a successful result than does a knee treated with primary operation.
- Bone Grafting:
- is 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 arthrodesis site to allow revascularization from surrounding soft tissues;
- intramedullary circulation of the bone is usually compromised by prior implant and cement