Flexion Gap Preparation Opens Both the Extension and Flexion Gap during Total Knee Arthroplasty

+Minoda Y, Iwaki H, Ikebuchi M, Yoshida T, Iida T, Ikawa T, Yamasaki S, Nakamura H. + Osaka City University Graduate School of Medicine, Osaka, Japan, [email protected] INTRODUCTION: Soft-tissue balancing of the knee is fundamental to the success of total knee arthroplasty (TKA). Preparing equal and rectangular extension and flexion joint gaps is the most important goal in TKA because this facilitates functional restoration of the knee [1]. Recent fluoroscopic kinematic study showed that rotation of the femoral component using a gap balancing technique resulted in better coronal stability than using measured technique and suggested that a gap balancing technique will improve functional performance and reduce polyethylene wear [2]. The different methods for gap balancing technique include the following: 1) initial preparation of the flexion gap followed by matching of the extension gap to the width of the flexion gap [3]; 2) initial preparation of the extension gap followed by matching of the flexion gap to the width of the extension gap [4]. The latter procedure, so called “modified gap technique”, minimizes the risk of joint line elevation. However, the theoretical disadvantage of the latter procedure is that the 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) would change the tension of the posterior soft tissue structures and thus the width of the extension and flexion gap, and disturb the preparing equal and rectangular extension and flexion joint gaps. Previous reports showed that the preparation of the flexion gap opens the extension gap either in posterior stabilized (PS) TKA [4] or cruciate ligament-retaining (CR) TKA [5]. To date, there is a paucity of data whether the flexion gap changes before and after the preparation of the flexion gap or not. The purpose of this study was to quantify the change in the extension and flexion gap caused by preparation of the flexion gap in PS TKA.