1️⃣ Evaluating Tibial Tunnel Placement: The Amis and Jakob Line
✅ The Amis and Jakob line is a commonly used reference to evaluate the anterior-posterior direction of the tibial tunnel.
It passes through the widest part of the posterior corner of the medial tibial plateau, parallel to the medial joint line from the anterior (0%) to the posterior (100%) border.
→ Normal values range from 27 to 60%.
✅ Relation to Blumensaat’s Line
In addition, the entire opening of the tibial tunnel must be posterior to the line drawn along Blumensaat’s line.
2️⃣ Implications of Tibial Tunnel Placement
✅ Risk of Graft Impingement
The tibial tunnel placed too anteriorly can cause a higher risk of graft impingement within the intercondylar notch, potentially resulting in an extension deficit or a Cyclops lesion.
✅ Impact on Knee Stability
Conversely, a tunnel placed too posteriorly may lead to a vertical graft orientation, compromising the knee's anteroposterior and rotatory stability.
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