Reproducibility of joint space width and the intermargin distance measurements in patients with medial osteoarthritis of the knee in various degrees of flexion.
OBJECTIVE
This study tested the variability and reproducibility of measurements of the joint space width (JSW) and intermargin distance (IMD) of the medial tibial plateau in specific positions of knee flexion in osteoarthritic knees in order to evaluate the most useful knee angle for radiographic measurements.


METHODS
Radiographs from 56 knees with osteoarthritis from 46 patients were taken with the knees in conventional full extension and 15 degrees , 30 degrees , and 45 degrees of flexion with weight bearing. Three orthopedic surgeons independently measured the JSW and IMD at the narrowest point and the midpoint of medial tibial plateau using a computer-assisted method.


RESULTS
The JSW and IMD were smallest at 15 degrees flexion, both measured at the narrowest point and the midpoint of the medial compartment. Reproducibility of the IMD at the midpoint was better than at the narrowest point for all four flexion angles.


CONCLUSIONS
Measurements of the medial JSW and IMD are smallest at 15 degrees of knee flexion indicating that radiographs should be obtained at this angle in order to best demonstrate the extent of osteoarthritis.
Takahashi
Toshiaki
T
Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan. takahast@m.ehime-u.ac.jp
Yamanaka
Norio
N
Ikeuchi
Masahiko
M
Yamamoto
Haruyasu
H
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D013977:Tibia / Q000000981:diagnostic imaging
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