Association of knee flexion angle after posterior-stabilized total knee arthroplasty with postoperative tibial external position relative to the femur and the extent of tibial internal rotation from knee extension to flexion.
BACKGROUND
This study evaluated the relationship between preoperative and postoperative knee kinematics, moreover, investigated tibial rotational position and the extent of tibial internal rotation from knee extension to flexion as factors to obtain significant knee flexion after total knee arthroplasty (TKA).


METHODS
Fifty-four patients (60 knees total; 15 males, 16 knees; 39 females, 44 knees) who underwent posterior-stabilized TKA using a navigation system were included. Intraoperative knee kinematics involving tibial rotational position relative to the femur and the extent of tibial internal rotation were examined at two time points: 1) after landmarks registration (pre-TKA) and 2) after skin closure (post-TKA). The relationship between the knee flexion angle at one year postoperatively and intraoperative tibial rotational position, or the extent of tibial rotation among several knee flexion angles calculated with a navigation system were investigated.


RESULTS
The postoperative knee flexion angle was positively associated with the preoperative flexion angle and intraoperative knee kinematics at post-TKA involving tibial external position relative to the femur at knee extension and the extent of tibial internal rotation from extension to 90° of flexion or to maximum flexion. There was a positive relationship between the extent of tibial internal rotation at pre-TKA and that at post-TKA.


CONCLUSIONS
The intraoperative kinematics of the extent of tibial internal rotation at post-TKA was influenced by that at pre-TKA. The greater external position of the tibia relative to the femur at knee extension and the greater extent of tibial internal rotation at post-TKA might lead to good knee flexion angle.
['Hanada|Mitsuru|M|', 'Hotta|Kensuke|K|', 'Furuhashi|Hiroki|H|', 'Koyama|Hiroshi|H|', 'Matsuyama|Yukihiro|Y|']
D000368:Aged D000369:Aged, 80 and over D019645:Arthroplasty, Replacement, Knee D001696:Biomechanical Phenomena D005260:Female D006801:Humans D007719:Knee Joint D008297:Male D008875:Middle Aged D020370:Osteoarthritis, Knee D016059:Range of Motion, Articular D012189:Retrospective Studies D012399:Rotation D025321:Surgery, Computer-Assisted
Knee flexion angle Total knee arthroplasty Tibial internal rotation Knee kinematics