During bone healing, which structure is formed when the cartilaginous callus is replaced by bone?

During bone healing, which structure is formed when the cartilaginous callus is replaced by bone?

• A. Bony Callus
• B. Fibrocartilage
• C. Osteoid
• D. Periosteum

Answer: (A)

During fracture healing, the cartilaginous (soft) callus is gradually replaced by bone through endochondral ossification, forming a bony callus. This stage creates woven bone that bridges and stabilizes the fracture as minerals deposit in the previously cartilaginous scaffold. The bony callus is the structure that marks the transition from cartilage to solid bone. Fibrocartilage represents the soft callus tissue that precedes the bone formation, not the final structure after replacement. Osteoid is the unmineralized bone matrix produced before mineralization, a precursor to bone, not the mature callus itself. The periosteum is the outer bone covering that supplies cells for healing, but it isn’t the new structure formed to replace cartilage.

During fracture healing, the cartilaginous (soft) callus is gradually replaced by bone through endochondral ossification, forming a bony callus. This stage creates woven bone that bridges and stabilizes the fracture as minerals deposit in the previously cartilaginous scaffold. The bony callus is the structure that marks the transition from cartilage to solid bone.

Fibrocartilage represents the soft callus tissue that precedes the bone formation, not the final structure after replacement. Osteoid is the unmineralized bone matrix produced before mineralization, a precursor to bone, not the mature callus itself. The periosteum is the outer bone covering that supplies cells for healing, but it isn’t the new structure formed to replace cartilage.