In vivo knee kinematics during high flexion after a posterior-substituting total knee arthroplasty.
The objective of this study was to investigate biomechanics of TKA patients during high flexion. Six patients (seven knees) with a posterior-substituting TKA and weight-bearing flexion >130 degrees were included in the study. The six degree-of-freedom kinematics, tibiofemoral contact, and cam-post contact were measured during a deep knee bend using dual-plane fluoroscopy. The patients achieved average weight-bearing flexion of 139.5 +/- 4.5 degrees. Posterior femoral translation and internal tibial rotation increased steadily beyond 90 degrees flexion, and a sharp increase in varus rotation was noted at maximum flexion. Initial cam-post engagement was observed at 100.3 +/- 6.7 degrees flexion. Five knees had cam-post disengagement before maximum flexion. Lateral femoral condylar lift-off was found in five out of seven knees at maximum flexion, and medial condylar lift-off was found in one knee. Future studies should investigate if the kinematic characteristics of posterior-substituting TKA knees noted in this study are causative factors of high knee flexion.
Moynihan
Angela L
AL
Department of Orthopaedic Surgery, Bioengineering Laboratory, Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, GRJ 1215, Boston, MA 02114, USA.
Varadarajan
Kartik M
KM
Hanson
George R
GR
Park
Sang-Eun
SE
Nha
Kyung Wook
KW
Suggs
Jeremy F
JF
Johnson
Todd
T
Li
Guoan
G
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008875:Middle Aged; D016059:Range of Motion, Articular; D013314:Stress, Mechanical; D016474:Weight-Bearing