Bone Structure and Function Quiz

Bone Structure and Function

• Bone is a specialized connective tissue acting as the endoskeleton
• Mechanical Functions:
  • Enables longitudinal growth of the body and extremities
  • Supports body parts
  • Protects vital soft tissues
  • Forms levers for muscle action and movement
• Biochemical Functions:
  • Stores minerals
  • Maintains homeostasis of certain ions
• Blood Formation:
  • Site of erythropoiesis (red blood cell production) in the bone marrow

Types of Bones

• Cortical (Compact) Bone:
  • Dense bone, providing support where needed
  • Forms the outer layer of all bones
  • Forms the shaft of tubular bones
  • Found on articular surfaces of bone ends
• Cancellous (Spongy, Trabecular) Bone:
  • Forms the inner meshwork of all bones
  • Found at the ends of tubular bones
  • Found within the vertebral bodies

Fractures: Definition and Mechanisms

• A fracture is a break in the structural continuity of a bone.
• Mechanisms of Injury:
  • Direct force: A force applied directly to the bone
  • Indirect force: A force applied elsewhere on the body
  • Combined force: A combination of direct and indirect forces
• Types of Force:
  • Single strong force: Causes classical fractures
  • Repeated minor force: Causes stress fractures
  • Normal force of daily activities: May cause pathological fractures

Types of Fractures (Incomplete)

• Crack: A small break in the bone
• Buckle fracture: Bone bends and the cortex buckles
• Greenstick fracture: Partially broken bone, common in children
• Compression (impacted) fracture: Bone is compressed

Types of Fractures (Complete)

• 2-fragment fracture: Bone breaks into two pieces
• Transverse fracture: Break is at a right angle to the bone's long axis
• Oblique fracture: Break at an angle to the bone's long axis
• Spiral fracture: Break wraps around the bone's long axis
• 3 or more fragment fracture: Bone breaks into 3 or more pieces, including butterfly, segmental, and comminuted fractures

Fracture Displacement

• Causes:
  • Same injury mechanism
  • Gravity
  • Pulling of attached muscles
• Types:
  • Shift (translation)
  • Tilt (angulation)
  • Twist (rotation)
  • Length (shortening/lengthening)

Fracture Healing Stages

• Hematoma formation: Blood clot forms at the fracture site
• Inflammation and granulation tissue formation: The body prepares for healing
• Callus formation: Cartilage and bone form a bridge across the fracture
• Consolidation: The callus is replaced by bone.
• Remodeling: Bone is reshaped and strengthened over time

Clinical Features of Fractures

• History (symptoms): Pain, swelling, deformity, limitation of movement, loss of function, and bruising
• Examination (signs): Look for swelling, deformity, bruising, wounds. Feel for tenderness and crepitation. Move the limb appropriately. Check neurovascular status distally

Investigations

• X-ray: Visualizes fractures
• CT scan: Detailed view of fractures, and surrounding soft tissue

Fracture Treatment

• General Treatment: Analgesia, fluid replacement, antibiotics
• Local Treatment: Reduction (closed or open), hold reduction (e.g., splint, traction, internal fixations, external fixations), exercises, and elevation

Fracture Complications

• General Complications: Hypovolemia, shock, DVT, PE, bedsores, UTI, and disuse atrophy
• Early Complications: Vascular injury, nerve injury, visceral injury, compartment syndrome, hemarthrosis, infection, fracture blisters, pressure sores
• Late Complications: Delayed union, nonunion, malunion, avascular necrosis, joint stiffness, heterotopic ossification, growth disturbances, nerve entrapment, reflex sympathetic dystrophy, osteoarthritis

Common Fractures (Upper Limb)

• Clavicle Fracture: Direct or indirect trauma, pain and swelling, medial/lateral segment displacement. Treatment: sling.
• Humerus Shaft Fracture: Direct trauma, pain, swelling, deformity, potential radial nerve injury. Treatment: surgery.
• Supracondylar Fracture of Distal Humerus: Indirect trauma, possible brachial artery injury. Treatment: surgery.
• Colles' Fracture: Fall on the hand, pain, swelling, dinner fork deformity, potential median nerve injury. Treatment: manipulation and cast splint.
• Scaphoid Fracture: Fall on the hand, pain, swelling, anatomical snuff box tenderness, potential avascular necrosis.

Common Fractures (Lower Limb)

• Neck of Femur Fracture: Indirect trauma, pain, inability to ambulate, potential avascular necrosis. Treatment: surgery
• Shaft of Femur Fracture: Direct or indirect trauma, pain, swelling, loss of function, risk of bleeding. Treatment: surgery.
• Supracondylar Fracture of Distal Femur: Indirect trauma, risk of popliteal artery injury. Treatment: surgery
• Proximal Fibula Fracture: Risk of common peroneal nerve injury, possible foot drop.
• Shaft of Tibia Fracture: Risk of overlying skin break with contamination (compound fracture).
• Calcaneus Fracture: Fall from height, possible pelvic and spinal fractures, chronic heel pain due to joint distortion.