All of the following factors facilitate nonunion except –
**Core Concept**
Nonunion in orthopedics refers to the failure of a fracture to heal, resulting in persistent bone instability and potentially leading to chronic pain, disability, and further complications. Various factors can contribute to nonunion, including inadequate blood supply, smoking, and certain medical conditions.
**Why the Correct Answer is Right**
Nonunion can be facilitated by factors that compromise the healing process, such as smoking, which reduces blood flow and impairs collagen synthesis. Additionally, diabetes mellitus can impair bone healing due to neuropathy and impaired wound healing. Smoking and diabetes mellitus are well-documented risk factors for nonunion.
**Why Each Wrong Option is Incorrect**
**Option A:** Smoking is a well-documented risk factor for nonunion, as it impairs blood flow and collagen synthesis, making it difficult for the fracture to heal.
**Option B:** Diabetes mellitus can impair bone healing due to neuropathy and impaired wound healing, making it a risk factor for nonunion.
**Option C:** Radiation therapy can impair bone healing by damaging the osteoblasts and impairing collagen synthesis, making it a risk factor for nonunion.
**Clinical Pearl / High-Yield Fact**
Smoking is a significant risk factor for nonunion, and quitting smoking can significantly improve the chances of successful fracture healing.
**Correct Answer: D.**