Sagittal bowing of the distal femur in Chinese patients who require total knee arthroplasty.
OBJECTIVE
The importance of the femoral sagittal bowing on total knee arthroplasty is under-recognized. The bowing could lead to potential errors in positioning of the femoral component if it is ignored. We aimed to document the femoral sagittal bowing at different segments of the Chinese femur and to discuss the implications of this sagittal bowing on total knee arthroplasty.


METHODS
One hundred lateral radiographs of the entire lower limbs of 85 Chinese patients admitted for total knee arthroplasty were digitized. The radii of curvature of the intramedullary canal of the proximal, middle and distal one-third of the femora were measured.


RESULTS
The average age of the patients was 67.3 years. The radii of curvature of the proximal, middle and distal one-third of the femora were 1081.6, 926.2 and 715.1 mm, respectively. The distal one-third of the femora was significantly more bowed than the other parts of the femora (p<0.001). The distal femoral bowing was more profound in rheumatoid patients and in those with a short femur.


CONCLUSIONS
The lateral contour of the Chinese femur is like a hockey stick. This exaggerated sagittal bowing in the Chinese femur can affect the final sagittal position of the femoral component and has implications for the choice of implant design. In revision setting, a long and straight press-fit stem might either endanger the anterior cortex or deflect the femoral component to an abnormally extended position.
Tang
W M
WM
Division of Joint Replacement Surgery, Department of Orthopedic Surgery, The University of Hong Kong, c/o Queen Mary Hospital, 102 Pokfulam Road, Hong Kong SAR, People's Republic of China. wmtanga@hkucc.hku.hk
Chiu
K Y
KY
Kwan
M F Y
MF
Ng
T P
TP
Yau
W P
WP
D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008875:Middle Aged; D011859:Radiography