Abstract
Background:
The Lateral Intercondylar Ridge (LIR) gained notoriety with arthroscopic trans-tibial Anterior Cruciate Ligament (ACL) reconstruction where it was mistakenly used to position the ‘over the top’ guide resulting in graft malposition.
With anatomic ACL reconstruction some surgeons use the same ridge to define the anterior margin of the ACL femoral insertion in order to guide graft placement. However there is debate about whether this ridge is a consistent and reliable anatomical structure.
The aim of our study was to identify whether the LIR is a consistent anatomical structure and to define its relationship with the femoral ACL insertion.
Methods:
In the first part, we studied 23 dry bone specimens. Using a digital microscribe, we created a 3D model of the medial surface of the lateral femoral condyle to evaluate whether there was an identifiable bony ridge.
In the second part, we studied 7 cadaveric specimens with soft tissues intact. The soft tissues were dissected to identify the femoral ACL insertion. A 3D reconstruction of the femoral insertion and the surface allowed us to define the relationship between the LIR and the ACL insertion.
Results:
All specimens (23 dry bones; 7 intact soft tissues) had a defined ridge on the medial surface of the lateral femoral condyle. The ridge extends from the apex point of the lateral intercondylar notch, where the posterior condyle meets the femoral shaft, and extends obliquely to the articular margin. The mean distance from the midpoint of the posterior condylar articular margin was 10.1 mm. The ridge was consistently located just anterior to the femoral ACL insertion.
Conclusion:
This study shows that the LIR is a consistent anatomical structure that defines the anterior margin of the femoral ACL insertion. This supports its use as a landmark for femoral tunnel placement in ACL reconstruction surgery.
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