- Location of Entry Hole:
- use a rongeur to remove any residual osteophytes from the intercondylar notch;
- use intercondylar drill guide to drill hole into center of medullary canal of the femur;
- normally the entry hole is placed slightly anterior to the insertion of the PCL on to the femur;
- excessive posterior placement most often results from mis-judging the top of the intercondylar notch (due
to inadequate debridement of notch osteophytes);
- placement of the drill hole too posterior can lead to flexion of the femoral component, which will
complicate the subsequent femoral cuts, and will lead to incomplete knee extension;
- generally the drill hole should be made 1 cm above the roof of the intercondylar notch, which will
keep the guide rod in the center of the medullary canal;
- vent the intramedullary canal by widening the drill hole in an AP direction (using a ronguer);
- this will allow the fatty contents of the medullary can to exit thru the drill rather than
be embolized as the alignment rod is driven retrograde;
- to assure that the medullary canal is unobstructed, pass the medullary rod into the drill hole
and up the medullary canal of the femur;
- Meduallary Guides:
- if properly applied, IM femoral alignment systems are accurate to w/in 1-2 degs of varus or valgus, & are more accurate than extramedullary jigs;
- use of extrameduallary alignment systems may be indicated in the case of ipsilateral hip arthroplasty with a long femoral
component, mal-alignment following a femoral fracture, or in the case of excessive excessive anterior bowing;
- radiograph of the entire femur is needed, so that when the IM guide is used, allowances can be made for bowing or deformity;
Effect of rotation on the axial alignment of the femur. Pitfalls in the use a of femoral intramedullary guides in total knee arthroplasty.
Blood-gas and circulatory changes during total knee replacement. Role of the intramedullary alignment rod.
Extramedullary versus intramedullary alignment guides in total knee arthroplasty.
The effect of prosthetic patellar thickness and anterior femoral surface on limiting flexion in total knee arthroplasty.
J Holtgrew et al.
Trans. Orthop. Res. Socl. Vol 14. 1989. p 369.
