Three-dimensional measurements of the lower extremity in children and adolescents using a low-dose biplanar X-ray device.
OBJECTIVE
To evaluate three-dimensional (3D) measurements of the lower extremity using a biplanar low-dose X-ray device in children and adolescents.


METHODS
Firstly, 3D measurements of eight dried bones were analysed by a biplanar low-dose X-ray device (LDX) using stereoscopic software and compared with 3D computed tomography (CT). Secondly, 47 lower limbs of children and adolescents were studied using LDX two-dimensional (2D) and 3D measurements. Both parts were evaluated for femoral and tibial lengths and mechanical angles, frontal and lateral knee angulations, and the femoral neck-shaft angle.


RESULTS
The 3D specimen comparison between LDX and CT measurements showed no significant differences: femoral length (P = 0.069), tibial length (P = 0.059), femoral mechanical angle (P = 0.475), tibial mechanical angle (P = 0.067), frontal knee angulation (P = 0.198), lateral knee angulation (P = 0.646) and femoral neck-shaft angle (P = 0.068). The comparison between LDX 2D and 3D measurements showed significant differences in tibial length (P = 0.003), femoral mechanical angle (P < 0.001) and femoral neck-shaft angle (P = 0.001); other parameters were unremarkable.


CONCLUSIONS
The 3D LDX system presented reliable measurements compared with 3D CT. Differences between LDX 2D and 3D measurements were noted in the femoral mechanical angle, femoral neck-shaft angle and tibial length. Moderate to good interobserver agreement for the 3D LDX measurements were found.


CONCLUSIONS
Low radiation dose is essential when assessing potential lower extremity discrepancies. A new biplanar low-dose X-ray device can assess such discrepancies in children/adolescents. This LDX device provides equally reliable 3D measurements as prevalent practice LDX measurements carry good overall interobserver agreement.
Department of Musculoskeletal Radiology, Centre Hospitalier Régional Universitaire de Lille, Hôpital Roger Salengro, Lille, France. rgheno@yahoo.com
Ramon
R
Gheno
Eric
E
Nectoux
Bernard
B
Herbaux
Matteo
M
Baldisserotto
Luiz
L
Glock
Anne
A
Cotten
Nathalie
N
Boutry
D000293:Adolescent; D001822:Body Burden; D002648:Child; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D007870:Leg Length Inequality / Q000000981:diagnostic imaging*; D008297:Male; D011829:Radiation Dosage; D011859:Radiography / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013977:Tibia / Q000000981:diagnostic imaging*