L20 - Introduction to soft tissue injury and fractures Flashcards
■Common injuries ■Why fractures happen ■Steps of tissue healing ■List basic treatment of fractures ■Relate biological tissue healing to function
List examples of soft tissue injuries?
SALAD PIC
Sprain injury (stretch joint/ soft tissue) Abrasions (grazes) Lacerations Avulsions Deglove injury
Puncture wound (i.e. dog bite)
Internal (closed) deglove injury
Contusion
What are the predominant causes of death due to injury?
~1/4: suicide (16%, top 20), homicide (10%)
~1/4: road traffic injuries
Other main causes: falls (14%, rising to 17th), drowning (7%), fire-related burns (5%), poisoning (4%)
What is the epidemiology of higher injury death rates?
higher injury death rates in:
Poorer countries (growing problem in some countries)
Men
Youth
What type of injuries do most young people have?
High energy, high mortality, Poly-trauma with multiple system involvement
What is the golden period of treatment for heart stop, respiration stop, Massive haemorrhage?
Heart stop: 50% death rate after 3 minutes
Respiration stop: 50% death rate after 10 minutes
Massive bleeding (haemorrhage): 50% death rate after 30 minutes
What type of injuries do most old people have?
Low energy, mostly slip and fall injuries
75% with head injury / fractures
What are the measures to prevent road traffic deaths?
speeding enforcements, drinking, helmets, seatbelts, child restraints, infrastructure upgrades, vehicle and equipment standards, graduated driver’s license
What causes contusion?
direct blow to tissue with blunt object, often resulting in ruptured capillaries and bruising
What causes abrasions?
caused by the skin rubbing against a rough surface
What causes lacerations?
tearing of the skin that results in an irregular wound (unlike a cut which preserves skin)
caused by injury with a sharp object or by impact injury from a blunt object or force
What causes avulsion?
forceful detachment of body part
a body structure is torn off by either trauma or surgery
What causes deglove injuries?
an extensive section of skin is completely torn off the underlying tissue, severing its blood supply
Incomplete avulsion with laceration on top
What causes internal deglove injury?
shearing force separates subcutaneous fat from deep fascia
> > simple / complex fluid collection (blood, serous, lymphatic, liquefied fat, and/or pus) in potential space
complication of puncture wounds?
bacteria in saliva > infection
List some types of fracture?
transverse, oblique, spiral (twisting), comminuated, avulsion (e.g. connected to ligament), impacted, fissure, greenstick
What are the 3 classification of fractures?
- Complete or incomplete
- Closed (overlying tissue is intact) or Compound (fracture extends into the overlying skin)
- Comminuted (bone is splintered) or Displaced (fractured bone is not aligned)
What is a pathologic fracture?
break occurs at the site of previous disease (e.g.,
a bone cyst, a malignant tumor…etc)
What is stress fracture?
develops slowly over time as a collection of microfractures associated with increased physical activity, especially with new repetitive mechanical loads on bone
What is the consequence and treatment of displaced intracapsular neck fracture?
- Avascular necrosis of femur head»_space; need to remove (cannot heal)
- Treatment: prosthesis replacement (hip-arthroplasty)
What types of injuries are common at fingers and wrists?
Lacerations, puncture, amputations (>50%)
Fractures (17%, less common)
What types of injuries are common at elbow to shoulder?
Fractures dislocations (~60%, more common)
Sprains, contusions (~30%)
What are the phases in skin wound healing?
1) Exudative phase
2) Resorptive phase
3) Proliferative phase
4) Repair phase
List what occurs in the exudative phase of wound healing?
Bleeding (haemorrhagic)
Clot: wound is filled with fibrin, coagulated blood (form clot)
List what occurs in the resorptive phase of wound healing?
Clearance + Granulation
Inflammation: scavenger cells (first polymorphonuclear neutrophils, then macrophages) remove dead cells, germs
Granulation: form fibrous tissue
List what occurs in the proliferative phase of wound healing?
Wound Contraction
Re-epithelization: new cells formed fill in the wound
Form fibrous scar
List what occurs in the repair phase of wound healing?
Epithelial remodeling
Skin creation and wound closure, scar formation
What are the 4 phases of tendon healing?
1) Bleeding
2) Inflammatory
3) Proliferative
4) Remodeling
List what occurs in the bleeding phase of tendon healing?
Open wound haemorrhage restricted by blood clot
Vasoconstriction to restrict local blood loss
List what occurs in the inflammatory phase of tendon healing?
(onset after hours,
maximum in 3 days)
Exudation + Clearance + Vasodilation
Leaky vessels for exudates, cause swelling, cells and growth factors for wound repair move in:
damaged cells, pathogens, and bacteria are removed from the wound area
Chemically amplified cytokine cascade for vasodilation
List what occurs in the proliferative phase of tendon healing?
2-3 weeks
**Scar + Re-epithelization + Wound contraction **
1) Fibrous scar formation: Recruit fibrocytes to deposit collagen
2) Re-epithelization: wound is rebuilt with disorganized collagen and extracellular matrix
3) Wound contraction: by myofibroblasts, agiogenesis to supply granulation tissue
List what occurs in the remodeling phase of tendon healing?
Months
Wound close + Resurface
epithelial cells resurface the injury
collagen is remodeled from type III to type I and the wound fully closes, collagen cross-linking and alignment, water re absorption
Cells for repair die
What are some pathological consequences of poorly regulated tissue healing?
Fibrosis, metaplasia and/or tumor growth
Infection, ischemia, poor perfusion
List some important growth factors for tendon and ligament healing?
Insulin-like growth factor (IGF-I)
Platelet-derived growth factor (PDGF)
Basic fibroblast growth factor (bFGF)
Transforming growth factor (TGFβ)
How does mechanical forces affect wound healing?
Mechanica loading stimulates protein synthesis:
Integrin proteins activate pathways for matrix remodeling
What are the 4 phases of bone healing?
1) Hematoma formation
2) Fibrocartilaginous callus formation
3) Bony callus formation
4) Bone remodeling
What occurs in the Hematoma formation phase of bone healing?
- Torn blood vessels hemorrhage, clot/ hematoma forms
- Inflammatory cells and fibroblasts infiltrate the bone
- Site becomes swollen, painful and inflamed
What occurs in the Fibrocartilaginous callus formation phase of bone healing?
- Phagocytic cells remove cellular debris, granulation tissue formation, vascular tissue ingrowth, mesenchymal cell migration
- Osteoblasts begin forming spongy bone within 1 week
- Fibroblasts secrete collagen fibers to connect fractured ends»_space; woven bone formation and endochondral ossification
- Mass of repair tissue = fibrocartilaginous callus (hold the ends of the fractured bone in apposition but is noncalcified )
What occurs in the Bony callus formation phase of bone healing?
Bone progenitors in the periosteum and medullary cavity deposit new foci of woven bone
Newly formed cartilage acts as nidues for endocondral ossification
Connects cortices and trabeculae in cortical bone and spongy bone
Final Ossification = bridge fractured ends with bony callus
What occurs in the Bone remodeling phase of bone healing?
In response to mechanical stress
Balance between bone formation (osteoblasts) and resorption (osteoclasts) to adjust the bone architecture
restores the original size, shape, and integrity of the bone.
What is the difference between primary and secondary bone healing?
Primary bone healing = involves a direct attempt by the cortex to re-establish itself after interruption without the formation of a fracture callus
Secondary bone healing = involves the classical stages of injury, hemorrhage inflammation, primary soft callus formation, callus mineralization, and callus remodeling.
What are the requirements for bone healing?
Stability
Blood supply
Bone contact and scaffold
Growth factors
Explain the cause of pseudoarthrosis in poor bone healing?
Inadequate immobilization and persistent movement
> > nonunion casuses central portion of callus to undergo cystic degeneration and create a FALSE JOINT
What are some hurdles to bone healing?
- Displaced and comminuted fractures result in deformity (loose bone fragments causes very long remodeling period)
- Inadequate immobilization cause pseudoarthrosis
- Infection
- Poor nutrition: Inadequate calcium or phosphorus, vitamin deficiencies
- Systemic diseases: systemic infection, diabetes, or vascular insufficiency
- Wound: Large gap, scar contracture
Why does secondary bone healing create longer healed bones?
Widening of healing zone = more mechanical stability
Conversion of fibrous soft callus to calcified hard callus = widening of bone
List some causes of iatrogenic necrosis of skin?
wounds too tight, excessive retraction, undermined skin flaps
Thermal necrosis from electrocautery, high-speed drilling
Which type of tissue can never heal properly in MSS?
Cartilage»_space; forms Fibrocartilage
Tendon, Muscle and bone heal better than cartilage
List the 2 classifications of nerve injury?
Seddon and Sunderland
Seddon = Neurapraxia, Axontmesis, Neurotmesis
Sunderland = Type 1 to 5
What are the pathophysiologic features of Neurapraxia?
Type 1 / Neurapraxia:
- Local myelin damage usually secondary to compression or pressure ischemia = conduction block
- Functional disruption with no anatomical discontinuity
- Nerve sheath intact
- No Wallerian degeneration
What are the pathophysiologic features of Axonotomesis?
Sunderland classification type 2-4 = Axontmesis
- Microscopic discontinuation of nerve axon and myelin sheath without discontinuity of nerve sheath
- With Wallerian regenration** loss of nerve conduction in distal segment, NO absence of distal sensory-motor response
- Partial or complete recovery → remaining uninjured mesenchymal latticework provides a path for subsequent sprouting axons for reinnervation
What are the pathophysiologic features of Neurotmesis?
Complete physiologic disruption of entire nerve trunk (axon and sheath disconnected)
Wallarian degeneration and no nerve conduction distal to site of injury
Describe the phases of Wallerian Degeneration?
axonal degeneration (axonal skeleton disintegration and breaking of axonal membrane)
→ degradation of myelin sheath and macrophage infiltration
→ clearance of debris from the degeneration
Schwann cells line up, axonal sprouts form
Schwann cells myelinate axon > recovery
What are the stages of Axonotomesis?
Type 2:
Loss of continuity of axons Sheath (endoneurium, perineurium, epineurium) intact
Type 3
Loss of continuity of axons, endoneurium
Perineurium, epineurium intact
Type 4
Loss of continuity of axons, endoneurium, perineurium
Epineurium intact
Compare the outcome between successful nerve regeneration and unsuccessful?
Successful = Muscle initially atrophy, then regenerate. Axonal sprouts finds its path to penetrate bands of Bungner
Unsuccessful = muscle atrophy, Disorganized axonal sprouts causing Neuroma (also caused by amputation)
How to treat neuroma?
Surgical treatment Desensitization Antiepileptics GABA receptor inhibitor Painkillers (opioids less effective)
List some chronic problems with non-healing tissue?
Ulcer with infection
Tissue gangrene
Explosed implant
The basics of treating a fracture?
Realign if deformed enough
Stabilize if unstable
Always rehab function
List some ways to help fractures heal?
1) External traction
2) Cast
3) External fixation
4) Internal fixation (Intramedullary nail)
5) Internal fixation (plating)
■Most likely to be high energy injury?
A. Oblique fracture of the neck of femur
B. Transverse fracture of tibia shaft
C. Oblique fracture of distal radius
D. Compression fracture of cervical spine
E. Spiral fracture of femur shaft
B. Transverse fracture of tibia shaft
