L20 - Introduction to soft tissue injury and fractures

Question 1

List examples of soft tissue injuries?

SALAD PIC

Answer 1

Sprain injury (stretch joint/ soft tissue) 
Abrasions (grazes) 
Lacerations 
Avulsions 
Deglove injury 

Puncture wound (i.e. dog bite)
Internal (closed) deglove injury
Contusion

Question 2

What are the predominant causes of death due to injury?

Answer 2

~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%)

Question 3

What is the epidemiology of higher injury death rates?

Answer 3

higher injury death rates in:
 Poorer countries (growing problem in some countries)

 Men

 Youth

Question 4

What type of injuries do most young people have?

Answer 4

High energy, high mortality, Poly-trauma with multiple system involvement

Question 5

What is the golden period of treatment for heart stop, respiration stop, Massive haemorrhage?

Answer 5

 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

Question 6

What type of injuries do most old people have?

Answer 6

Low energy, mostly slip and fall injuries

75% with head injury / fractures

Question 7

What are the measures to prevent road traffic deaths?

Answer 7

speeding enforcements, drinking, helmets, seatbelts, child restraints, infrastructure upgrades, vehicle and equipment standards, graduated driver’s license

Question 8

What causes contusion?

Answer 8

direct blow to tissue with blunt object, often resulting in ruptured capillaries and bruising

Question 9

What causes abrasions?

Answer 9

caused by the skin rubbing against a rough surface

Question 10

What causes lacerations?

Answer 10

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

Question 11

What causes avulsion?

Answer 11

forceful detachment of body part

a body structure is torn off by either trauma or surgery

Question 12

What causes deglove injuries?

Answer 12

an extensive section of skin is completely torn off the underlying tissue, severing its blood supply

Incomplete avulsion with laceration on top

Question 13

What causes internal deglove injury?

Answer 13

shearing force separates subcutaneous fat from deep fascia

> > simple / complex fluid collection (blood, serous, lymphatic, liquefied fat, and/or pus) in potential space

Question 14

complication of puncture wounds?

Answer 14

bacteria in saliva > infection

Question 15

List some types of fracture?

Answer 15

transverse, oblique, spiral (twisting), comminuated, avulsion (e.g. connected to ligament), impacted, fissure, greenstick

Question 16

What are the 3 classification of fractures?

Answer 16

• 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)

Question 17

What is a pathologic fracture?

Answer 17

break occurs at the site of previous disease (e.g.,

a bone cyst, a malignant tumor…etc)

Question 18

What is stress fracture?

Answer 18

develops slowly over time as a collection of microfractures associated with increased physical activity, especially with new repetitive mechanical loads on bone

Question 19

What is the consequence and treatment of displaced intracapsular neck fracture?

Answer 19

• Avascular necrosis of femur head&raquo_space; need to remove (cannot heal)
• Treatment: prosthesis replacement (hip-arthroplasty)

Question 20

What types of injuries are common at fingers and wrists?

Answer 20

 Lacerations, puncture, amputations (>50%)

 Fractures (17%, less common)

Question 21

What types of injuries are common at elbow to shoulder?

Answer 21

 Fractures dislocations (~60%, more common)

 Sprains, contusions (~30%)

Question 22

What are the phases in skin wound healing?

Answer 22

1) Exudative phase
2) Resorptive phase
3) Proliferative phase
4) Repair phase

Question 23

List what occurs in the exudative phase of wound healing?

Answer 23

 Bleeding (haemorrhagic)

 Clot: wound is filled with fibrin, coagulated blood (form clot)

Question 24

List what occurs in the resorptive phase of wound healing?

Answer 24

Clearance + Granulation

 Inflammation: scavenger cells (first polymorphonuclear neutrophils, then macrophages) remove dead cells, germs

 Granulation: form fibrous tissue

Question 25

List what occurs in the proliferative phase of wound healing?

Answer 25

 Wound Contraction  Re-epithelization: new cells formed fill in the wound  Form fibrous scar

Question 26

List what occurs in the repair phase of wound healing?

Answer 26

Epithelial remodeling Skin creation and wound closure, scar formation

Question 27

What are the 4 phases of tendon healing?

Answer 27

1) Bleeding 2) Inflammatory 3) Proliferative 4) Remodeling

Question 28

List what occurs in the bleeding phase of tendon healing?

Answer 28

Open wound haemorrhage restricted by blood clot Vasoconstriction to restrict local blood loss

Question 29

List what occurs in the inflammatory phase of tendon healing?

Answer 29

(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

Question 30

List what occurs in the proliferative phase of tendon healing?

Answer 30

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

Question 31

List what occurs in the remodeling phase of tendon healing?

Answer 31

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

Question 32

What are some pathological consequences of poorly regulated tissue healing?

Answer 32

Fibrosis, metaplasia and/or tumor growth Infection, ischemia, poor perfusion

Question 33

List some important growth factors for tendon and ligament healing?

Answer 33

Insulin-like growth factor (IGF-I) Platelet-derived growth factor (PDGF) Basic fibroblast growth factor (bFGF) Transforming growth factor (TGFβ)

Question 34

How does mechanical forces affect wound healing?

Answer 34

Mechanica loading stimulates protein synthesis: Integrin proteins activate pathways for matrix remodeling

Question 35

What are the 4 phases of bone healing?

Answer 35

1) Hematoma formation 2) Fibrocartilaginous callus formation 3) Bony callus formation 4) Bone remodeling

Question 36

What occurs in the Hematoma formation phase of bone healing?

Answer 36

- Torn blood vessels hemorrhage, clot/ hematoma forms - Inflammatory cells and fibroblasts infiltrate the bone - Site becomes swollen, painful and inflamed

Question 37

What occurs in the Fibrocartilaginous callus formation phase of bone healing?

Answer 37

- 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 >> woven bone formation and endochondral ossification - Mass of repair tissue = fibrocartilaginous callus (hold the ends of the fractured bone in apposition but is noncalcified )

Question 38

What occurs in the Bony callus formation phase of bone healing?

Answer 38

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

Question 39

What occurs in the Bone remodeling phase of bone healing?

Answer 39

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.

Question 40

What is the difference between primary and secondary bone healing?

Answer 40

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.

Question 41

What are the requirements for bone healing?

Answer 41

Stability Blood supply Bone contact and scaffold Growth factors

Question 42

Explain the cause of pseudoarthrosis in poor bone healing?

Answer 42

Inadequate immobilization and persistent movement >> nonunion casuses central portion of callus to undergo cystic degeneration and create a FALSE JOINT

Question 43

What are some hurdles to bone healing?

Answer 43

- 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

Question 44

Why does secondary bone healing create longer healed bones?

Answer 44

Widening of healing zone = more mechanical stability Conversion of fibrous soft callus to calcified hard callus = widening of bone

Question 45

List some causes of iatrogenic necrosis of skin?

Answer 45

wounds too tight, excessive retraction, undermined skin flaps Thermal necrosis from electrocautery, high-speed drilling

Question 46

Which type of tissue can never heal properly in MSS?

Answer 46

Cartilage >> forms Fibrocartilage Tendon, Muscle and bone heal better than cartilage

Question 47

List the 2 classifications of nerve injury?

Answer 47

Seddon and Sunderland Seddon = Neurapraxia, Axontmesis, Neurotmesis Sunderland = Type 1 to 5

Question 48

What are the pathophysiologic features of Neurapraxia?

Answer 48

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

Question 49

What are the pathophysiologic features of Axonotomesis?

Answer 49

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

Question 50

What are the pathophysiologic features of Neurotmesis?

Answer 50

Complete physiologic disruption of entire nerve trunk (axon and sheath disconnected) Wallarian degeneration and no nerve conduction distal to site of injury

Question 51

Describe the phases of Wallerian Degeneration?

Answer 51

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

Question 52

What are the stages of Axonotomesis?

Answer 52

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

Question 53

Compare the outcome between successful nerve regeneration and unsuccessful?

Answer 53

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)

Question 54

How to treat neuroma?

Answer 54

```  Surgical treatment  Desensitization  Antiepileptics  GABA receptor inhibitor  Painkillers (opioids less effective) ```

Question 55

List some chronic problems with non-healing tissue?

Answer 55

Ulcer with infection Tissue gangrene Explosed implant

Question 56

The basics of treating a fracture?

Answer 56

Realign if deformed enough Stabilize if unstable Always rehab function

Question 57

List some ways to help fractures heal?

Answer 57

1) External traction 2) Cast 3) External fixation 4) Internal fixation (Intramedullary nail) 5) Internal fixation (plating)

Question 58

■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

Answer 58

B. Transverse fracture of tibia shaft