Knee Replacement has always been about alignment. A recent article by Pagnano et al shook the very foundations of knee replacement by claiming that alignment is a poor predictor of the durability of the implant. Ritter et al however think otherwise. They too studied a huge no of knees (6070) and concluded that alignment is after all important.
I am worried about alignment as I don’t have the luxury of navigation yet. I came across this interesting article. The authors claim that preoperative varus deformity predisposes to varus malposition of the implants. Furthermore, they say that more the varus, more is the risk of malposition. However this is not true for valgus knees in which malposition and malalignment were rare. (I find that difficult to digest)
They used an intramedullary guide for both the femur and the tibia. With varus bowing in the tibia, intramedullary guides can go wrong. This was studied by Teter et al. However they also concluded that extramedullary instrumentation is no better.
Dennis et al recommended that the extramedullary guides should be distally positioned over the center of the talus (3 mm medial to the midpoint of the ankle) to avoid varus tibial resection.
Coming back to the article in question, the authors could not specify the reasons for the varus postop alignment. It is obviously a technical issue. It is an error of the instrumentation or an error of the surgeon’s technique.
The take home message would be to be careful about alignment. Plan properly. Check and recheck during surgery. And be more careful whilst operating varus knees. Happy Replacing!!
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