Final answer:
The minimum amount of diaphyseal bone required to support a fully coated stem depends on the Paprosky classification and the type of stem. A long fully coated stem requires a significant amount of healthy diaphyseal bone, while a revision modular stem can compensate for bone loss.
Step-by-step explanation:
The minimum amount of diaphyseal bone required to support a fully coated stem depends on the Paprosky classification and whether it is a long fully coated stem or a revision modular stem. According to the Paprosky classification, a long fully coated stem requires a Paprosky type 2A or better bone quality in the diaphysis. This means that a significant amount of healthy diaphyseal bone is needed to support the stem securely.
In contrast, a revision modular stem may require less diaphyseal bone as it is designed to compensate for bone loss and can be adjusted to different sizes and lengths.
Therefore, the minimum amount of diaphyseal bone required to support a long fully coated stem is greater than that required for a revision modular stem.