What are the two basic requirements for primary bone healing?

What are the two basic requirements for primary bone healing?

• A. Intact vascular supply and stable rigid fixation
• B. Movable fixation and robust blood supply
• C. Soft tissue coverage and callus formation
• D. Vitamin D deficiency

Answer: (A)

Primary bone healing occurs only when two conditions are met: an intact vascular supply and stable, rigid fixation. The blood supply delivers the osteogenic cells, nutrients, and signaling factors needed for bone remodeling across the fracture line. At the same time, rigid fixation minimizes interfragmentary motion, keeping the bone ends in close apposition so healing can proceed directly through osteons without forming a callus. If the blood supply is compromised, healing slows or fails; if fixation isn’t rigid, micro-motion promotes secondary healing with callus formation rather than direct bone remodeling. The other options describe factors not sufficient or not necessary for primary healing—movable fixation, or issues like vitamin D deficiency—while soft tissue coverage relates to overall healing but isn’t the specific pair required for primary bone healing.

Primary bone healing occurs only when two conditions are met: an intact vascular supply and stable, rigid fixation. The blood supply delivers the osteogenic cells, nutrients, and signaling factors needed for bone remodeling across the fracture line. At the same time, rigid fixation minimizes interfragmentary motion, keeping the bone ends in close apposition so healing can proceed directly through osteons without forming a callus. If the blood supply is compromised, healing slows or fails; if fixation isn’t rigid, micro-motion promotes secondary healing with callus formation rather than direct bone remodeling. The other options describe factors not sufficient or not necessary for primary healing—movable fixation, or issues like vitamin D deficiency—while soft tissue coverage relates to overall healing but isn’t the specific pair required for primary bone healing.