Award-winning study details simple method to make anatomic ACL femoral tunnels
BALTIMORE — Research presented at the American Orthopaedic Society for Sports Medicine Annual Meeting 2012 yielded helpful guidelines for anatomic femoral tunnel placement in ACL reconstruction.
“We know that it is important to produce an anatomic femoral tunnel and an anatomic ACL, but there are two questions,” Alexander D. Davis, MD, said in his presentation of the work, for which he and his colleagues received the Aircast Award for Basic Science. “How do we find the anatomic femoral insertion and how do we create a tunnel at this location?”
Davis and colleagues removed the medial condyles from 12 fresh, frozen distal femurs. They dissected all the soft tissue except the ACL attachment and marked the centers of the ACL and its two bundles. The researchers than observed the femur in 90° flexion and marked the lowest point on the lateral wall of the notch. This point was then used as the starting point for a vertical line, against which Davis and colleagues measured the height of the ACL center and its composite bundles. They then measured the distance from those center points to the front and back of the notch.
The team placed metal beads at these three centers and took lateral radiographs using the quadrant method, according to Davis. They then seated a 7-mm femoral offset aimer at the vertical height of the ACL center, he said, and placed a pin through the aimer to mark a point on the lateral wall of the notch.
Results of the study illustrated that the femoral attachment of the ACL and its bundles can be identified through a method based on the height of these structures on the lateral wall of the notch, Davis said. Intra-operatively, a 7-mm femoral offset aimer seated at the height of the central ACL directs a pin about halfway between the ACL central and anteromedial bundle attachments. Then the shallow and deep ACL positions and their bundles can be referenced to a vertical line that starts at the low point of the notch’s lateral wall or cartilage borders, he explained.
“Whether you are using rigid reamers in a hyperflexed position or flexible reamers, once you have established your starting point you can then produce an anatomic femoral tunnel that is based upon a reproducible reference point that can be seen intra-operatively based upon the lowest point of articular cartilage,” Davis said.
Reference:
Davis AD, Brown C, Steiner ME. Simple guidelines for anatomic femoral tunnel placement in ACL reconstruction. Paper #17. Presented at the American Orthopaedic Society for Sports Medicine Annual Meeting 2012. July 12-15. Baltimore.
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