Importance of Saw Blades In Knee Arthroplasty

By Ravindra Vartak

The success of knee arthroplasty depends on correct bone cuts. Precision of bone cuts can affect proper placement and orientation of implants. Instrumentation, cutting guides and TKR blades are surgeon’s assistants in ensuring quality cuts and in reducing efforts of the surgeon.

The sharpness, flatness, hardness and thickness of the blade play important role in cutting the bone as per the requirement.

1) Sharpness of TKR blade: Sharper the blade accurate will be the cut. If the teeth of the blade are blunt then it requires more oscillations of the saw to complete the cut resulting heat generation at the cutting points in bone. This is undesirable. Also the blunt blade requires the surgeon to apply more ‘push force’ during the cut resulting in the skiving of the blade which makes the blade to move in the different plane and the accuracy of the cut is totally lost. Sharp TKR blade means better cuts, faster cutting, shorter surgery times and effortless cutting. This is the reason many surgeons insist of fresh blades for every knee.

2) Flatness of the blade: The blade used for the sagittal saw should have a flatness in the limit of 0.05 mm to 0.1 mm., beyond that blade starts hitting on the saw capture of the cutting guide resulting in vibrations and skiving of the blade resulting in wrong cut.

3) Hardness of the blade: The saw blade should be optimally hard. Excessive hardness can make the blade brittle. This is extremely undesirable and dangerous. At the same time a soft blade would blunt out during surgery may cause adverse effects already described above.

4) Thickness of the blade: There are good number of TKR implant models available in the market and each model has its specific instrument sets which specifies the thickness of the blade to be used. It varies from 0.9mm to 1.27 mm. Surgeon should use appropriate thickness of the blade as specified in the surgical technique. If blade is thinner than recommended then cutting guide/block may not be able to guide it properly and can cause improper angular orientation of cuts. If the blade is thicker than recommended then it may cause increased friction with the saw capture of the cutting guide. This would not only cause increase wear of the saw capture but it would also cause surgeon to apply excessive force leading to the possibility of disturbing alignment of instrumentation and subsequent disorientation of cuts

During my hands on experience of many years, it is my observation that surgeons are occupied with many important issues during surgery and importance of quality of bone saw blades sometimes get overlooked. I would like to emphasize here that good quality and sharpness TKR Blades play a significant role in improving quality of knee arthroplasty

(About author: Ravindra Vartak is mechanical engineer with decades of experience in joint replacement, both knee and hip arthroplasty. He has designed number of innovative instrumentations to the appreciation of leading surgeons. He has Indian and US patents on his name)