Fracture Healing Flashcards
What is a fracture?
Any structural break in continuity of bone
Fractures are accompanied by significant soft
tissue injury
Soft tissue injury determines severity of injury and speed of rehabilitation
Bone Biomechanics
Bone mineral (hydroxyapatite) strongest in compression - where the calcium is
Bone matrix (collagen) strongest in tension
Open and Closed Fractures
Open fracture:
Any break in the skin that extends down to
bone
Much higher infection risk
More soft tissue damage, takes longer to heal
Closed fracture:
Skin is intact
Less infection risk, less soft tissue damage
Description: Displacement
Undisplaced:
Buckle, hairline
Impacted
Displaced:
Lateral shift (percentage)
Angulation
Lengthening or shortening
Pediatric Fractures: Salter–Harris Classification
Type I: fracture through growth plate
Type II: fracture exits through metaphysis
Type III: fracture exits through epiphysis (intra- articular)
Type IV: transverse, across growth plate (intra-articular)
Fracture Healing Stages
Inflammation
Soft callus
Hard callus
Remodeling
Inflammatory Stage
Lasts 1–3 days
Clinically: pain swelling and heat
Fracture hematoma clots at fracture site
Inflammatory cells migrate into region
Soft Callus Stage
Early stage
Clinically stability is poor
Osteogenic “repair cells” from periosteum infiltrate hematoma
Chondroblasts form cartilage callus fracture site
becomes “sticky”
Osteogenic cells differentiate into osteoblasts
Cartilage callus is converted into woven type bone
Callus becomes evidenton X-ray at end of stage
Hard Callus Stage
Clinical union (about 6–12 weeks)
Clinically fracture site no longer moves
Cartilage is replaced by woven bone
Callus is well developed on X-ray
Remodeling Phase
Proceeds for years
Wolff’s law:
Bone responds to stress, becoming stronger
Osteoblasts lay down new bone along lines of stress
Osteoclasts resorb poorly located bone
Factors That Affect Healing: Age
Children heal much quicker
Adolescents to older adults heal similarly
Elderly only heal slower when malnourished or when they have medical conditions
Factors That Affect Healing: Site and Configuration
Metaphyseal bone heals faster than diaphyseal
(Better blood supply)
Comminuted fractures heal slower (> soft tissue injury, compromised blood supply to fragments)
Pediatric growth plate injuries heal in half the time (cellular machinery “geared up” for healing)
Factors That Affect Healing: Initial Displacement
More displaced heals slower
More soft tissue damage
More vascular disruption
Factors That Affect Healing: Blood Supply
Fractures need good blood supply to heal
Scaphoid in wrist has poor blood supply
Tibia is subcutaneous, not surrounded by muscle, and has a poorer blood supply
Vascular injuries or disease can affect
healing.
Closed Reduction
Displaced fractures need to be reduced (straightened)
If stable after reduction, then cast immobilization
If unstable after reduction, then percutaneous or external fixation
Open Reduction
Fractures that cannot be reduced closed need to be surgically opened
Bones can be directly manipulated and aligned
Internal fixation (plates and screws) is used to hold fracture
Common Fractures
Proximal humerus (surgical neck)
Distal radius (Colles)
Scaphoid (navicular)
Hip
Femur
Tibia
Ankle
Complications in fractures
Malunion
Nonunion
Infection
Compartment syndrome
Complex regional pain syndrome - Reflex sympathetic dystrophy (RSD)
Malunion
Fracture heals normally
Unacceptable alignment
Nonunion
Fracture does not show any sign of healing by three months
Need to stimulate bone to heal
Electrical stimulator
Bone grafting
Improved immobilization
Infection
Possible after any surgical procedure
More common with open fractures
More common with diabetes
Compartment Syndrome
Vascular compromise caused by extreme swelling
Tissue pressure becomes higher than venous pressure
Blood can get in, but can’t get out: circulation is blocked
Muscle compartment becomes ischemic and muscle dies
Complex Regional Pain Syndrome
Pain, swelling, and autonomic dysfunction are hallmarks
Early: constant burning, aching, pain out of proportion to injury; edema can rapidly lead to joint stiffness
Middle: cold, glossy skin with decreased ROM
Late: atrophy and contractures
Stage 1: 3-6 months
Stage 2: 3-6 months
Stage 3: may last years
