Abstract
[Introduction]
As an essential concept in TKA, preparing equalized rectangular extension and flexion gaps is recognized as desirable to ensure proper knee kinematics.
However, in the ways that was recommended by an implant manufacturer, the adjustments are so difficult, and for inexperienced doctor, we don't have an ideal technique for an additional cutting up and ligament balancing.
Then, the New method (Precut method) was introduced in order to enable an ideal adjustments.
[Method]
Sixty eights patients with osteoarthritis of the knee received TKAs using Precut method. This method is the following. At first, proximal tibia was resected 10 mm by standard cutting device. And then, femoral posterior condyle was resected 4 mm lesser than cutting line by measured resection technique (Precut method). In the next, using the spacer block 1 mm unit and the Precut trial implant (8 mm; distal femur 4 mm; posterior condyle), we investigated the bone gap and the component gap (put the Precut trial on the distal femur). Finally, we calculated the amount of the final cutting value based on the component gap.
The survey item measured the bone gap at extension and flexion, the component gap at extension and flexion after putting the Precut trial on.
Then we compared the gap difference with and without the Precut trial.
[Result]
Our results showed that the extension gap with the Precut trial was smaller than the predicted value with the Precut trial (mean: 8.66 mm/8.18 mm), the flexion gap with the Precut trial was larger than the predicted value with the Precut trial (mean: 13.2 mm/14.1 mm).
The extension gap had reduced by 0.48 mm and the flexion gap enlarged by 0.3 mm.
[Discussion]
In TKA, it is difficult to make extension gap and flexion gap equal. Therefore, after putting the final implant, we experienced the case s such as could not stretch fully in extension, such as had instability in flexion.
However, in this method, we will earn the ideal stability in postoperative condition. It is because that after putting the Precut trial, we measured implant gap at extension and flexion, and then decided the final osteotomy value to eliminate the gap difference.
[Conclusion]
As we measured extension gap and flexion gap in condition which put the Precut trial on, before the final osteotomy, we can make an equal gap at extension and flexion.
We think a useful procedure for the stability after TKA.
