[Development of a 3-dimensional method to determine the tibial slope with multislice-CT].
OBJECTIVE
The measurement or, respectively, the correction of the tibial slope is an important subject in the field of knee arthroplasty and in the procedure of cruciate ligament reconstruction. However, a valid value of the tibial slope cannot be obtained from the conventional plain X-rays in a reproducible way. The aim of this study was to evaluate the proximal tibial slope with a new CT measurement system and to compare the values with the X-ray method.


METHODS
Using 6 cadaver tibiae, the antero-posterior slope of the proximal tibia was measured at 0 degrees, 2.5 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 30 degrees internal rotation using the plain X-ray and spiral CT (3D-MPR reconstruction). Both methods were compared.


RESULTS
The variation of the measurement of the tibial slope with the X-ray method was > 5 degrees even if the optimal 0 degrees rotation in the lateral view was applied. Moreover, the measurement error increased to 14 degrees while increasing the rotation of the tibia. Using the new CT system, the error was less than 3 degrees in all measurements.


CONCLUSIONS
The measurement of the tibial slope in the conventional X-ray technique showed a high variation of the values depending on the rotation of the tibia in the lateral view. In contrast, the measurements with the new CT system represented a precise method with a small variation of the tibial slope values. For this reason detailed questions regarding the precise anatomy of the proximal tibia cannot be answered precisely with plain X-rays.
Kessler
M A
MA
Abteilung und Poliklinik für Sportorthopädie der Technischen Universität München, Munich. info@markus-kessler.de
Burkart
A
A
Martinek
V
V
Beer
A
A
Imhoff
A B
AB
D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000601:surgery*; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D017760:Bone Malalignment / Q000000981:diagnostic imaging* / Q000517:prevention & control; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007718:Knee Injuries / Q000000981:diagnostic imaging / Q000601:surgery*; D007719:Knee Joint / Q000000981:diagnostic imaging; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000517:prevention & control; D012016:Reference Values; D012399:Rotation; D013977:Tibia / Q000000981:diagnostic imaging*; D036542:Tomography, Spiral Computed / Q000379:methods*
Entwicklung eines 3-dimensionalen Messverfahrens zur Bestimmung des tibialen Gefälles im Spiral-CT.