Injury+Healing Flashcards
What are bones made of?(2)
Cells and matrix
What is the organic component of bone matrix made up out of?
What is the inorganic component of bone matrix made up out of?
Purpose of osteogenic cells?
Bone stem cell
Purpose of osteoblasts?
Producing bone
-Secretes osteoid
-Catalyses mineralisation of osteoid
Purpose of osteoclasts?
Destroying bone
-Dissolve+reabsorb bone via phagocytosis
-Derived from bone marrow
Purpose of osteocytes?
‘Mature’ bone cell
-Formed when an osteoblast becomes imbedded in its secretions
-Sense mechanical strain to direct osteoclast and osteoblast activity
What type of ossification produces long bones?
Endochondral
Mesenchymal>Cartilage>Bone
What type of ossification produces flat bones?
Intramembranous
Mesenchymal>bone
What is involved in endochondral ossification?
- Bone collar formation
- Cavitation
- Periosteal bud invasion
- Diaphysis elongation
- Epiphyseal elongation
What is involved in intramembranous ossification?
- Condensation of mesenchymal cells which differentiate into osteoblasts that secrete matrix (osteoid)
- Secreted osteoid traps osteoblasts which become osteocytes. A bunch of these together form an ossification center
- Multiple ossification centers form and fuse. Trabecular matrix and periosteum form
- Compact bone develops superficial to cancellous bone. Crowded blood vessels bring in mesenchymal cells and form red marrow
What are the primary and secondary ossification centers in endochondral ossification?
Primary-Diaphysis
Secondary-Epiphysis
What key feature in mature bone is not present in immature bone?
Lamellar (layer) structure – relatively strong
Which type of ossification is faster?
Intramembranous
Where are bone trabeculae found?
Cancellous bone
What are the differences in the 2 types of mature bone?
Cancellous bone-
‘Spongy’ – honeycomb structure
Not suitable for weight baring
Cortical bone-
‘Compact’ – dense
Suitable for weight baring
What is haversians canal?
A passageway containing blood vessels, nerves and lymphatics in the center of an osteon
What are the 2 layers in the periosteum?
Inner osteogenic layer
Outer fibrous layer
What are bone osteons?
Circular structures in cortical bone with repeating lamellae
What are volkmans canals?
Transverse perforating canals
What are bone lacunae
Small spaces containing osteocytes
Tiny Canaliculi radiate from lacunae filled with extracellular fluid.
What does the medullary cavity contain?
Yellow bone marrow
Where is articular cartilage found?
On surface of bone at joint only
Where do you find osteogenic cells?
Marrow + Deep layers of periosteum
Where do you find osteoblasts?
Growing portions of bone incl. periosteum and endosteum
Where do you find osteoclasts?
Bone surfaces and sites of old, injured or unneeded bone
Where do you find osteocytes?
Entrapped in matrix
What are the 2 different types of growth where bones increase in length and thickness
Interstitial-Length
Appositional-Thickness
How and where does interstitial growth occur?
Happens at the physis (physeal plate)
Zone of elongation in long bone
Contains hyaline cartilage
Epiphyseal side – hyaline cartilage active and dividing to form hyaline cartilage matrix
Diaphyseal side – Cartilage calcifies and dies and then replaced by bone
How and where does appositional growth occur?
- Ridges in periosteum create groove for periosteal blood vessel
- Periosteal ridges fuse, forming an endosteum-lined tunnel
- Osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel, forming a new osteon
- Bone grows outwards as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessel.
- Even without injury or exercise, about 5 to 10 percent of the skeleton is remodeled annually just by destroying old bone and renewing it with fresh bone
During appositional growth, osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum.
What occurs when calcium is above normal to regulate it?
What occurs when calcium is below normal to regulate it?
Where is calcitonin produced and what is its overall function?
Thyroid
To stimulate bone Ca2+ reabsorption
What is the pathway to a stress fracture?
What are the mechanisms of bone fracture/break?
What are the pathways to pathological/insufficiency bone fractures 6,4?
What are the 4 insufficiencies that lead to pathological fractures?
- Osteopenia/osteoporosis
- Vit D deficiency
- Congenital osteogenesis imperfecta
- Pagets disease
What causes osteopenia/osteoporosis and describe its epidemiology?
Osteoclast activity > Osteoblast activity
>Disrupted microarchitecture
Female > Male 4:1
Postmenopausal Osteoporosis – Women 50-70
Senile Osteoporosis - > 70
Secondary osteoporosis: Any age, 60% Male
Hypogonadism
Glucocorticoid excess
Alcoholism
Associated with ‘fragility fractures’ – hip, spine, wrist
Low energy trauma fracture
Describe the epidemiology of Vit D deficiency
Vitamin D facilitates calcium, magnesium and phosphate absorption
Dietary or synthesized from the sun
Inadequate Calcium or Phosphate Defect in osteoid matrix mineralization
Paeds – Rickets
Adults - Osteomalacia
What causes pagets disease and what are the 4 stages?
Genetic & Acquired factors
Excessive bone break down and disorganized remodeling deformity, pain, fracture or arthritis
May transform into a malignant disease
4 stages:
Osteoclastic Activity
Mixed osteoclastic-osteoblastic activity
Osteoblastic activity
Malignant degeneration
What causes congenital osteogenesis imperfecta?
‘Brittle Bone Disease’
Hereditary – autosomal dominant or recessive
Decreased Type I Collagen due to:
Decreased secretion
Production of abnormal collagen
Insufficient osteoid production
Effects:
Bones
Hearing
Heart
Sight
What are the 4 primary bone cancers?
What are the 4 major stages of bone healing and what subtances/cells are required for each?
What types of cancers are bone forming(blastic) and bone breaking(lytic)?
What does Wolff’s law dictate?
Wolff’s Law: Bone Grows and Remodels in response to the forces that are placed on it
What are the 3 stages of fracture healing?
What occurs in the inflammation stage in fracture healing?
Haematoma formation
Release of Cytokines
Granulation tissue and blood vessel formation
What occurs in the repair stage in fracture healing?
Soft Callus formation
(Type II Collagen - Cartilage)
Converted to hard callus
(Type I Collagen - Bone)
What occurs in the remodelling stage in fracture healing?
Callus responds to activity, external forces, functional demands and growth
Excess bone is removed
What occurs in secondary bone healing?
Endochondral healing
Involves responses in the periosteum and external soft tissues
Relative stability
Endochondral ossification: more callus
What occurs in primary bone healing?
Intramembranous healing
Absolute stability
Direct to woven bone
Which image is more likely primary and secondary bone healing?
Primary-Left
Secondary-Right
-Secondary bone healing produces more callus
How many days does it take for bone healing to be visible on an X-ray?
7-10 days
What do you require once taking a radiograph of a broken bone?
A second image from a perpendicular angle e.g AP and lateral or PA and lateral
What is the pathway for fracture management?
What are the methods of fixation and their groups?
What is the pathway for rehabilitating a broken bone?(4+2)
What are ligaments and tendons made up of?
Type 1 collagen
What is the purpose of ligaments and tendons?
Ligaments – connect bone to bone
Restricts joint motion
Stability and proprioception
Tendons – connect muscle to bone
Transmits forces
How do you grade tendon/ligament injury?
Grade I – Slight incomplete tear – no notable joint instability
Grade II – Moderate / Severe Incomplete Tear – Some joint instability. One ligament may be completely torn
Grade III – complete tearing of 1 or more ligaments – Obvious instability. Surgery may be required
What 3 signs are indicative of an ACL tear?
Lachmans
Anterior drawer
Pivot shift
What are the steps involved in tendon/ligament healing and how is it different to bone healing?
Bleeding
Inflammation
Proliferation
Re-modelling
A longer process
Maximum strength recovery at >6 months
May never fully recover full tensile strength
ACL role?
Stabilizes the knee joint by preventing excessive forward movements of the tibia or limiting rotational knee movements
ACL tear symptoms
A loud pop or a “popping” sensation in the knee.
Severe pain and inability to continue activity.
Rapid swelling.
Loss of range of motion.
A feeling of instability or “giving way” with weight bearing.
What is the short term management of an ACL tear?
Protect
Rest
Ice
Compress
Elevate
What are the 2 long term ACL rupture treatment pathways?
What do you need to consider in an ACL tear patient?
Functional Demands
Patient factors
Compliance
What are the risk factors for an achilles rupture?
30-50s M
Anabolic steroid use
Fluroquinolone
‘Weekend Warrior’
Symptoms of an achilles tear?
Difficulty walking / limp.
Unable to perform heel raises (stand on tip toes)
Thickening, tenderness and swelling on the affected side
When prone with feet off the end of couch the affected side is held in dorsiflexion
What test can be used to check for an achilles tear?
Simmonds calf squeeze test
What factors do you base the management of an achilles tear on?
Functional Demands
Patient Factors
Injury Factors
Based on USS/MRI
Acute/Chronic
Give some complications of operating on a achilles tendon injury
General (early or late):
DVT
Infection
Prolonged immobility (UTI, chest infections, sores)
Specific
Neurovascular injury
Sural nerve
Tendon re-rupture
Local infection
Ankle stiffness
Pressure sores from plaster or boot
Reduced Strength
