OTA 2006 Posters
Scientific Poster #74 Basic Science
Ideal Tibial Intramedullary Nail Insertion Point Varies with Tibial Rotation
Richard Walker, MD (n); Michael D. McKee, MD (n);
James P. Waddell, MD (n); Emil H. Schemitsch, MD (n);
St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
Purpose: Intramedullary nailing of proximal tibial fractures remains
a challenge. The purpose of this study was to examine how the "ideal"
tibial nail insertion point varies with tibial rotation and to determine
what radiographic landmarks can be used to identify the most suitable rotational
view for insertion of a tibial intramedullary nail.
Methods: 12 cadaveric lower limb specimens with intact soft tissues
around the knee and ankle joints were used. A 2.0-mm Kirschner wire was
placed in the center of the anatomic safe zone and centered on the tibial
shaft. The leg was rotated and imaged using a fluoroscopic C-arm until the
K-wire was positioned just medial to the lateral tibial spine (defined as
the neutral anteroposterior radiograph). The leg was then fixed and radiographs
were taken in 5° increments by rotating the fluoroscope internally and
externally (in total, a 50° arc). Following this, a second K-wire was
placed in 5-mm increments both medially and laterally and the fluoroscope
rotated until this second K-wire was positioned just medial to the lateral
tibial spine. Radiographs were digitized for measurements.
Results: Given the presence of a 30° rotational arc through which
the radiograph appeared anteroposterior, it was possible to improperly translate
the start point up to 15 mm. Relative external rotation of the image used
for nail placement led to a medial insertion site when using the lateral
tibial spine as the landmark. A line drawn at the lateral edge of the tibial
plateau to bisect the fibula head correlated with an entry point that was
central or up to 5 mm lateral to the ideal entry point. The use of a fibula
head bisector line avoided a medial insertion point.
Conclusion: Rotation of the tibia may result in up to 15 mm of translation
of the start point that may be unrecognized. Relative external rotation
of the film used for nail placement leads to medial insertion sites when
using the lateral tibial spine as a landmark. The fibula head bisector line
can be used to avoid choosing external rotation views and thus avoid medial
insertion points.
If noted, the author indicates something of value received.
The codes are identified as a-research or institutional support; b-miscellaneous
funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts
disclosed, and *disclosure not available at time of printing.
·
The FDA has not cleared this drug and/or medical device for the use
described in this presentation (i.e., the drug or medical device is being
discussed for an "off label" use). · · FDA
information not available at time of printing.