What is the difference between a complete and incomplete fracture?
A complete bone fracture is a condition in which there is a complete break in the continuity of a bone.
In an incomplete bone fracture only some of the bone trabeculae are completely sectioned, while others are twisted or remain intact.
Describe a Greenstick fracture
Greenstick fractures are incomplete fractures where there is only disruption to one side of the compact bone.
It tends to occur in children more frequently because their bone is still soft.
Results from an angulated longitudinal force applied down the bone (e.g. an indirect trauma following a fall on an outstretched arm), or after a force applied perpendicular to the bone (e.g. a direct blow).
Is the most common incomplete fracture
Describe a torus fracture
Torus fractures (also known as buckle fractures) are incomplete fractures of the shaft of a long bone that is characterised by bulging of the cortical bone.
They usually result from trabecular compression from an axial loading force such as falling on an outstretched arm
Common in children
They are less common than greenstick fractures
Characterise a displaced fracture
Characterise spiral fractures
Displaced fractures refer to the misalignment of distal bone in complete fractures
Spiral fractures, otherwise known and torsion fractures, occur during high force rotational movements -> results in a spiral shaped fracture. These fractures tend to heal better because there are larger amounts of bone surface for reunion to occur.
What is the difference between open/compound vs closed/simple fractures
In open/compound fractures, bone penetrates the skin and communicates with the external surface.
Closed/simple fractures remain contained within the body tissue surrounding it
What is a comminuted fracture?
How does this compare with a butterfly fracture?
Communited fractures involve the splintering and disociation of atleast two bone fragments as a result of the fracture.
Butterfly fractures are a type of comminuted fracture and refers to a particular pattern of splintering.
Characterise stress fractures
Stress fractures occur following repeated low force injuries to a bone.
They are often very difficult to pick up on an x-ray; require nuclear medicine to identify sites of active bone repair to identify
Describe pathological fractures
Occur due to weakness resulting from abnormal bone pathologies such as osteoporosis, metastases and etc.
Osteoporotic fracture of the vertebrae is reasonably common
Characterise the four stages of fracture healing
1. Inflammatory Stage
- Occurs for the first week following injury
- Haematoma formation
- fibrin mesh creates a framewok
- platelets and leukocytes release inflammatory cytokines
- bone cells activated to begin repair of bone
- Granulation tissue forms
2. Reparative Soft Callous Phase
- Days to several weeks
- Chondrocytes lay down cartilagenous soft callous
- Holds the fractured ends of the bone together but no structural rigidity
- Periosteum repairs itself over the outside of the soft callous
3. Reparative Hard Callous Phase
- Weeks to months
- Ostioid formation and ossification
- Woven bone
- Endochondral ossification similar to that of growth plates replaces cartilage with bone
- Thickened area of woven bone eventuates that is rigid - but not as strong as it was.
4. Remodelling
- Months to years
- Bone remodelling occurs
- Woven bone is converted to lamellar bone with Haversian systems along lines of stress
- End result is complete reconstitution that, eventually, is indistinguishable from other bone.
Does a soft callous always form in the process of fracture healing?
No
If the bone ends are closely apposed, a soft callous is not required.
Healing occurs much faster (but perhaps won’t be as strong in the early stage of repair)
This doesn’t often occur - only if the environment is right: strains of less than 5% and hydrostatic pressures less than 0.15 MPa
The process of bone formation is similar to intramembranous ossification
What are the goals of fracture clinical management?
The ultimate goal of management is to achieve union of the bone ends
- This allows bone healing to occur as fast possible and without complications
This achieved by:
- minimising the gap (or reduction of the fracture) between the bones
- minimise the strain or movement of the fracture (fixation)
- minimise factors that may slow healing
- poor blood supply, infection, smoking etc.
**This may involved using surgically implanted plates and braces **
List some factors that impede bone healing processes
- Old age (>40)
- Multiple medical morbidities (diabetes etc.)
- NSAIDS and Corticosteroids
- Smoking
- Poor nutrition
- Open fracture
- Poor blood supply
- Multiple traumatic injuries
- Local infection
What complications can result of improper fracture healing?
Non Union
A fracture which will not heal, no matter how long primary management is persisted with. Can lead to **pseudo-arthrosis **where a false joint forms. Intervention is required to fix non-union; including:
- further stabilations
- treating infections
- bone grafting
- stop smoking
Delayed Union
A fracture that is not healing as fast as expected. Similar risk factors that impede bone repair. May lead eventually to non-union.
Mal-union
Healing of a bone in an abnormal and unacceptable position. This can result in:
- disability
- post-traumatic osteoarthritis
- cosmetic deformities
_Infection _
Osteomyelitis is a severe and disasterous condition. The infection commonly results from Staph. aureus.
Can cause destruction of bone and/or sepsis
Open (compound) fractures are at greatest risk.
Osteonecrosis
Fractures can disrupt the blood supply and leave parts of the bone ischaemic. Most commonly occurs in:
- Neck of femur
- Proximal scaphoid (blood supply is via distal scaphoid
Characterise **osteoporosis **
Osteoporosis is the reduced mass of otherwise normal bone.
It occurs as a result of an imbalance favouring bone resorption > bone production from around the age of 30. This is due to changes in osteoblasts, menopause and drugs.
A persons peak bone mass aquired in young adulthood is important in whether osteoporosis is likely to have a clinically significant effect in elder patients. It is determined by:
- Physical activity
- Calcium/vit D nutrition
- Endocrine environment
- Genetics
It can occur pathologically in astronauts, paralysis and annorexia nervosa
What is Paget’s Disease?
Paget’s Disease, otherwise known as osteitis deformans, is a disorder of increased, but disordered and structurally unsound, bone mass.
This unique skeletal disease can be divided into three sequential phases:
(1) Osteolytic stage
- multitudes of giant osteoclasts breaking down and resorbing bone
(2) Mixed osteoclastic-osteoblastic stage,
- Significant bone resorption and formation at the same time
(3) Osteosclerotic stage
- Predominant osteoblast stage that leads to the formation of thickened but structurally unsound bone
The result of this process is bone that:
- has thick, soft cortical bone
- has coarse trabeculae
- is easily fractured
- can compress nerves and vessels
What is osteomalacia?
What is Rickets disease?
Osteomalacia and Rickets are terms for the same pathological process; differentiated by its occurance in adults and chilren respectively.
They are manifestations of vitamin D deficiency or its abnormal metabolism whereby an inability to effectively utilise dietary Ca2+is incurred.
Compensatory elevation in PTH mobilises calcium and phosphate (leading to hypophosphatemia) from bone.
This leads to an impairment of mineralization and a resultant accumulation of unmineralized matrix known as osteoid
This is a loss of structural rigidity
Describe the effects of hyperparathyroidism on bone
Hyperparathyroidism results in increased osteoclastic activity on bone as indirectly mediated by PTH.
Parathyroid hormone results in:
- Indirect osteoclast activation increasing bone resorption and calcium mobilization.
- PTH mediates the effect indirectly by increased RANKL expression on osteoblasts
- Increased resorption of calcium by the renal tubules
- Increased urinary excretion of phosphates
- Increased synthesis of active vitamin D, by the kidneys
- Enhances calcium absorption from the gut and mobilizes bone calcium by inducing RANKL on osteoblasts
Note: intermittant doses of PTH induce osteoblasts without inducing osteoclasts -> hyperparathyroidism leads to dominant osteoclast activity
Discuss metastises that develop in bone
Bony metastases (“bony mets”) are multiple, invasive and poorly demarcated lesions in bone.
The metastases cause bone damage by influencing RANK-L or PTH - do not act directly.
Bone mets can be either **osteolytic **(abnormally low density mineralisation) or osteosclerotic (abnormally high density mineralisation)
Primary bone tumours are extremely rare; but secondary metastases are reasonably common - originating from:
- breast
- bronchus
- thyroid
- kidney
- prostate
- bowel
Note: 66% of bony metastases are derived from breast or prostate cancers
Presenting symptoms tend to include: pathological fractures, hypercalcaemia, bone marrow failure and/or **bone pain **
