## Introduction
In Total Knee Arthroplasty (TKA), the **Tibial Tray** is the foundation of the entire construct. If the tray does not adequately cover the top of the tibia, the physiological loads are not distributed evenly, leading to “subsidence” (the implant sinking into the bone) and eventual loosening.
## The Problem with Symmetric Trays
Older tibial trays were often perfectly symmetric. However, the human tibia is asymmetric鈥攖he medial side is larger than the lateral side.
* **Undersizing:** Leaving bare bone exposed increases the risk of tibial collapse.
* **Oversizing:** Overhang causes irritation to the pes anserinus or iliotibial band.
## The Anatomical Solution
Modern Ortholyx tibial trays are designed with an **Anatomical Contour** (Medial/Lateral specific).
1. **Maximum Cortical Support:** By matching the shape of the bone, the tray can sit on the dense “cortical rim” rather than just the soft cancellous center.
2. **Optimized Rotation:** Anatomic shapes naturally guide the surgeon to the correct rotational alignment.
3. **Low-Stress Interface:** Even load distribution significantly reduces the risk of “halos” or radiolucent lines on post-op X-rays.
## Material and Fixation
Ortholyx anatomical trays are available in **Ti6Al4V** for cementless biological fixation or **Cobalt-Chrome** for traditional cemented applications. Both feature a high-precision locking mechanism for the polyethylene insert.
## Conclusion
Foundation is everything. By choosing an anatomical tibial tray design, surgeons ensure that their knee replacements have the maximum support needed for decades of weight-bearing function.