- Discusssion:
- remove 1-2mm of bone using the intramedullary guide.
- be aware of the preoperative flexion stability and ROM in choosing posterior slope;
- for example, if the knee was unstable in flexion preoperatively, 0 degrees posterior slope may help reduce some of the flexion gap;
- reaming for medullary stems:
- after reaming to 12 mm, continue to procede slowly by 1 mm increments;
- reaming should cease once firm resistance is encountered;
- it is not necessary to have direct cortical contact, inorder to avoid excessive bone loss;
- generally, stem diameter will be the same size as the reaming diameter;
- debridement of remaining membrane debris:
- all reactive membranes need to be removed;
- insertion of trial tibial component:
- place an appropriately sized tibial component and stem;
- keep this component in position during femoral preparation;
- typically it will be necessary to insert intra-medullary stems;
- it is essential that the intra-medullary stem be inserted centrally in the medullary canal, which may or may not conform to the
center of the cut tibial surface;
- if there is a descrepancy between central medullary rod position and an optimally positioned tibial joint surface, the difference is
made up w/ tibial wedges;
- the tibial surface may have to be recut to conform to the wedges;
- tibial rotational alignment
- unlike a primary TKR, the trial tibial component usually cannot "find its optimal alignment" in relation to the femoral
component because the tibial stem locks the component in fixed rotation;
- consider alignment based on the center of the femoral component trochlea and tibial tubercle
- remove 1-2mm of bone using the intramedullary guide.
- be aware of the preoperative flexion stability and ROM in choosing posterior slope;
- for example, if the knee was unstable in flexion preoperatively, 0 degrees posterior slope may help reduce some of the flexion gap;
- reaming for medullary stems:
- after reaming to 12 mm, continue to procede slowly by 1 mm increments;
- reaming should cease once firm resistance is encountered;
- it is not necessary to have direct cortical contact, inorder to avoid excessive bone loss;
- generally, stem diameter will be the same size as the reaming diameter;
- debridement of remaining membrane debris:
- all reactive membranes need to be removed;
- insertion of trial tibial component:
- place an appropriately sized tibial component and stem;
- keep this component in position during femoral preparation;
- typically it will be necessary to insert intra-medullary stems;
- it is essential that the intra-medullary stem be inserted centrally in the medullary canal, which may or may not conform to the
center of the cut tibial surface;
- if there is a descrepancy between central medullary rod position and an optimally positioned tibial joint surface, the difference is
made up w/ tibial wedges;
- the tibial surface may have to be recut to conform to the wedges;
- tibial rotational alignment
- unlike a primary TKR, the trial tibial component usually cannot "find its optimal alignment" in relation to the femoral
component because the tibial stem locks the component in fixed rotation;
- consider alignment based on the center of the femoral component trochlea and tibial tubercle
- References:
- Tibial Stems in Revision Total Knee Arthroplasty: Is There an Anatomic Conflict?