Factors affecting range of motion after total knee arthroplasty in patients with more than 120 degrees of preoperative flexion angle.
OBJECTIVE
The postoperative flexion angle reportedly shows a positive correlation with the preoperative flexion angle, but in some cases, the postoperative flexion angle decreases in patients with a large preoperative flexion angle. The purpose of this study was to investigate factors affecting the range of motion after total knee arthroplasty (TKA) in patients with a large preoperative flexion angle.


METHODS
The study evaluated 120 knees with more than 120 degrees of preoperative flexion angle that underwent NexGen LPS-Flex mobile bearing. The groups with and without a reduction in the postoperative flexion angle were compared. Also, a logistic regression analysis was performed, where the presence or absence of a reduction in the postoperative flexion angle was the dependent variable and age, sex, body mass index (BMI), preoperative femorotibial angle (FTA), γ angle, δ angle, pre/postoperative change amount in posterior condylar offset (PCO), pre/postoperative change amount in joint line, and pre/postoperative change amount in patellar thickness were independent variables.


RESULTS
Those with preoperative FTA of 186° or larger did not have a reduction in the postoperative flexion angle, compared with the angle of 185° or smaller. Those with δ angle of 83° or smaller also did not have a reduction in the postoperative flexion angle, compared with the angle of 84° or larger.


CONCLUSIONS
Our results showed that preoperative FTA and δ angle had an impact on a reduction in the postoperative flexion angle. The installation angle of the tibial component in the sagittal plane is important.
Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan, sugikazuyasugi@yahoo.co.jp.
Kazuya
K
Sugitani
Yuji
Y
Arai
Hisatake
H
Takamiya
Ryu
R
Terauchi
Shuji
S
Nakagawa
Keiichiro
K
Ueshima
Toshikazu
T
Kubo
D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery; D011184:Postoperative Period; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D016896:Treatment Outcome