Fracture Healing & Bone Remodeling & Healing Complications Flashcards
What are the three phases of fracture healing?
Inflammatory, reparative, and remodeling phases
What happens during the inflammatory phase of fracture healing?
A hematoma forms, and inflammation begins to clear necrotic tissue
What is the purpose of the hematoma in fracture healing?
It provides a temporary framework for new tissue formation
What cells are responsible for forming soft callus?
Chondrocytes from the endosteum and periosteal osteoblasts
How does soft callus become hard callus?
Osteoblasts replace fibrocartilage with woven bone
What happens during the remodeling phase of fracture healing?
Woven bone is replaced by lamellar bone for strength
What are the specialized cells in bone tissue?
Osteoblasts, osteoclasts, osteocytes, and osteogenic cells
What type of bone cell is responsible for bone remodeling?
Both osteoblasts and osteoclasts
What is the primary role of osteocytes?
Regulating bone metabolism and maintaining the bone matrix
What is the difference between cortical and trabecular bone?
Cortical bone is dense and strong; trabecular bone is porous and flexible
What is the main structural unit of cortical bone?
The osteon (Haversian system)
What is the function of the Haversian canal?
It contains blood vessels and nerves for bone nutrition
What are the two types of microscopic bone?
Woven bone and lamellar bone
Why is woven bone weaker than lamellar bone?
Its collagen fibers are randomly arranged, making it less organized
How is woven bone replaced by lamellar bone?
Through bone remodeling, where osteoclasts resorb woven bone and osteoblasts replace it
What type of fracture is common in osteoporotic patients?
Pathologic fractures
What causes stress fractures?
Repetitive mechanical loading that exceeds the bone’s ability to repair
How do bones heal in primary fracture healing?
Through direct remodeling without callus formation
How do bones heal in secondary fracture healing?
By forming a callus before remodeling
What are the two main types of bone ossification?
Intramembranous and endochondral ossification
What type of ossification is responsible for fracture healing?
Mostly endochondral ossification
What type of ossification occurs in flat bones of the skull?
Intramembranous ossification
What factors can delay bone healing?
Poor blood supply, inadequate immobilization, infection, and poor nutrition
Why does poor blood supply delay bone healing?
Bone cells rely on blood flow for oxygen and nutrients
What are the common causes of osteonecrosis?
Trauma, corticosteroid use, alcohol abuse, and vascular diseases
Why is osteonecrosis often progressive?
The affected bone loses blood supply, leading to tissue death and joint destruction
What is the histological appearance of osteonecrosis?
Empty lacunae with degenerating bone marrow
What are the clinical symptoms of osteonecrosis?
Initially asymptomatic, progressing to pain with movement, then pain at rest
Where does osteonecrosis commonly occur?
The femoral head, humeral head, knee, and talus
What is a common long-term consequence of osteonecrosis?
Joint collapse and osteoarthritis
What are the main complications of fracture healing?
Delayed union, non-union, malunion, infection, and osteonecrosis
