Osteology, Fractures and Fracture Healing Flashcards
How many bones are in the human skeleton?
206
Which is the largest and smallest bone in the human body?
Largest = femur Smallest = stapes
What are the different bone types in the human body?
Long Short Flat Irregular Sesamoid
Classify each of the following bones:
- Cuboid
- Humerus
- Patella
- Vertebrae
- Sternum
Cuboid = Short Humerus = Long Patella = Sesamoid Vertebrae = Irregular Sternum = Flat
What is the main function of flat bones?
Protecting organs in the body especially vulnerable ones such as the lungs
List some of the functions of bones:
Protection Locomotion and Support Through muscle attachment Storage of Mineral Salts Production of Red Blood Cells (RBC) Secretory endocrine organ
Bones are important in storage of mineral salts, specifically which of these are important in the bones?
Calcium and Phosphate
Certain bones are hemopoietic, what does this mean?
They contain stem cells which specialise into red blood cells
Explain the function of bone as a secretory endocrine organ
Osteocalcin which has a regulatory effect on insulin
What gives bones a smooth, white outer appearance?
The compact / cortical bone
What is the function of compact / cortical bone
Protection, support and movement
In which bones is cancellous / spongy bone found?
Short, Flat and Irregular bones (and the ends of long bones)
Describe the structure of compact / cortical bone:
Compact bone is densely structured and incredibly hard
Describe the structure of cancellous / spongy bone:
Open cell, porous network with trabeculae
likened to the structure of honeycomb
What are trabeculae?
Stress lines in cancellous / spongy bone which withstand force in certain directions
Describe the structure of a long bone:
The shaft is comprised entirely of compact / cortical bone to provide resistance to compression The epiphysis (ends) are comprised mainly of cancellous / spongy bone to provide multi-directional force resistance
Describe the structure of a flat bone:
Cancellous / spongy bone sandwiched between a thick layer of compact / cortical bone to provide protection whilst remaining light
Describe the structure of a short bone:
Cancellous / spongy bone surrounded by a very thin layer of compact / cortical bone, cancellous / spongy bone allows absorption of a variety of force directions
Describe the structure of an irregular bone:
Cancellous / spongy bone surrounded by a very thin layer of compact / cortical bone, cancellous / spongy bone allows absorption of a variety of force directions
What are the three main parts of a long bone?
Epiphysis – upon
Metaphysis – after
Diaphysis – through
What is the epiphysis?
The end of a long bone
Forms articulation with another bone at a joint
Receives pressure and bears weight
What is the metaphysis?
The neck of a long bone
Contains growth plates in U25s
What is the diaphysis?
The shaft of a long bone
Made of compact / cortical bone
Contains the bone marrow cavity
In which section of a long bone is the bone marrow cavity?
Diaphysis (shaft)
Where in a long bone are the growth plates found?
Metaphysis (neck)
What is the periosteum?
The most external structure of a long bone, formed of two layers: the outer fibrous layer and inner osteogenic layer
What is the most external layer of a long bone?
Periosteum (two layers - the outer layer is more external, this is called the outer fibrous layer)
What is the most internal layer of a long bone?
Haversian systems (osteons) and interstitial lamellae
What are the different transverse layers of a long bone?
Periosteum is the most external structure
Circumferential lamellae
Compact bone
What is the Volkmann’s canal?
A structure in the circumferential lamellae which allows the neurovascular bundle to pass through a bone
What separates the Haversian systems from the Endosteum and Marrow cavity?
Inner circumferential layers (onion layers)
What is Endosteum?
A single layer of connective tissue in long bones which contains Osteoprogenitor (stem) cells
What is the structure of woven bone?
A haphazard arrangement of collagen fibres
Where is woven bone found
Fetal bones and Calluses (fracture healing)
What are the 3 main components of bone?
Extracellular matrix (type I collagen, protein gel) Inorganic mineral salt (calcium, phosphate) Bone cells (osteoblasts, osteocytes, osteoclasts, osteogenic cells)
What are the different bone cells?
Osteocyte (maintains bone tissue)
Osteoblast (form bone matrix)
Osteogenic cell (stem cell)
Osteoclast (reabsorbs older bone)
Explain why bone is not an inert tissue:
When a bone is subject to stress, small electrical signals stimulate osteocytes for bone growth. Cells respond to strengthen the region along the line of stress
What is a fracture?
A loss of continuity within the substance of a bone
What can cause a fracture?
Trauma, pathology or prolonged exposure to high force (a rather all-encompassing definition)
What is the different between a bone fracture and a bone break?
There is no difference between a fracture and a break
What is a stress fracture?
Where a bone has a prolonged exposure to a high force
Through what means can fractures be classified?
Mechanism (traumatic / pathologic)
Open or closed
Joint involvement
Displacement (displaced / non-displaced)
Pattern (linear / spiral / oblique / wedge / avulsed / segmental)
Fragmentation (complete / incomplete / communited)
What is meant by a traumatic fracture?
A fracture arising from a high force, e.g. a car crash
What is meant by a pathologic fracture?
A fracture arising from a smaller force but the bone is weakened, e.g. the bone has a tumour present so content is less
What is meant by a closed fracture?
A fracture where the skin is still intact, the fracture occurred within the body
What is meant by an open fracture?
A fracture where the bone fragment has penetrated the skin
What is meant by a fracture with joint involvement?
A fracture located at the articulating part of a bone
What is meant by a fracture with no joint involvement?
A fracture located not at the articulating part of a bone
What is meant by a displaced fracture?
A fracture where bones can be translated, rotated, angulated or overlapping
What is meant by a non-displaced fracture?
A fracture where the bone remains in its relative anatomical position
What is meant by the pattern of a fracture?
A descriptive of a fracture from a radiograph, such as linear, spiral, oblique, wedge, avulsed or segmental
What is meant by a complete fracture?
A fracture where bones remain in contact, e.g. a hairline fracture
What is meant by an incomplete fracture?
A fracture where bones are separated
What is meant by a communited fracture?
A fracture where the bone has been fractured into multiple fragments (often specular on an x-ray
What type of fracture are amongst the hardest to resolve?
Open and Communited sue to the complexity of piecing bones back together and the risk of infection inevitably lead to surgery
Is fracture healing a repair or regeneration process?
Regeneration process
What is the difference between repair and regeneration?
Repair = tissue formed in healing is different to what was there before Regeneration = tissue formed in healing is same as what there was before
What are the two main types of fracture healing?
Primary and Secondary
What are the different stages of secondary fracture healing?
- Haematoma
- Cellular proliferation and cartilage model formation
- Callus formation
- Consolidation of callus
- Remodelling
Explain the formation of a haematoma:
Trauma to the structure of bone disrupts blood vessels causing a bleed
Undamaged periosteum will prevent blood regress
Clotting factors and platelets stimulate clotting of blood
Torn blood vessels lead to necrosis at bone ends
New blood vessels, stimulated by acidic conditions of cellular breakdown and VGF sprout from undamaged vessels and grow towards site
Cellular proliferation occurs as stem cells begin differentiation into osteoblasts and chondroblasts
Describe fracture healing in cancellous bone:
Same 5 stages as secondary healing
Outer layer healing lags behind cancellous healing and no callus formation occurs, overall the fracture heals quickly with few complications
What local factors may affect the rate of healing of a fracture?
Fracture characteristics
Infection
Blood supply
What systemic factors may affect the rate of healing of a fracture?
Age Obesity Anaemia Endocrine conditions Steroid use Malnutrition Smoking
Give a very rough guide to time taken for fracture healing:
Bones join in 8 weeks:
Double this for the lower limbs
Half this for children
