The flexion gap preparation does not disturb the modified gap technique in posterior stabilized total knee arthroplasty

Preparation of the flexion gap (resection of the posterior femoral condyle and removal of the osteophytes on the posterior aspect of the femur to re-establish the posterior capsular recess) during modified gap technique might change the soft-tissue balancing and disturb the preparation of equal and rectangular extension and flexion joint gaps. The purpose of this study was to measure the change in the extension and flexion gaps using tension device during posterior stabilized TKA with modified gap technique.

We examined changes in the extension gap and flexion gap during posterior stabilized TKA using modified gap technique in 100 consecutive varus osteoarthritis knees. The extension gap was first prepared and then the distance and angle of both extension and flexion gaps were measured before and after preparation of the flexion gap using a tension device.

Although both the extension and flexion gaps significantly increased during the operation, the amount of the increase was very small, and the difference between the increase in the extension gap (0.9 ± 0.1 mm [mean ± SE]) and that in the flexion gap (0.7 ± 0.1 mm) was not statistically significant. Mean angular changes in extension and flexion gaps during the operation were less than 1°.

The preparation of the flexion gap in posterior stabilized TKA did not disturb the modified gap technique in terms of equal and rectangular extension and flexion gaps.