Bone Growth and Fractures Flashcards
When does growth in height end?
The end of puberty
Describe the cessation of bone growth
Sex steroids stimulate growth spurt but promote closure of epiphyseal plates
Growth in length ceases, cell proliferation slows and plate thins
Plate is invaded by blood vessels, epiphyseal and diaphyseal vessels unite
May leave a line visible on x rays
Where are the ossification centres in bones?
Depends:
Some have only one
• Carpals, tarsals, ear ossicles
Most bones have 2+
• Head of humerus has 3
Appearance in age varies • Allows est. of skeletal vs chronological age Rate of growth varies • From bone to bone • Within same bone
What are the zones of the epiphyseal plate?
Resting zone
Growth (proliferating) zone
Hypertrophic zone
Calcification zone
Ossification (osteogenic) zone
What is an example of a disease in the resting zone of the epiphyseal plates?
Diastrophic dwarfism
- Defective collagen synthesis/processing of proteoglycans
What is an example of a disease in the growth zone of the epiphyseal plates?
Achondroplasia Malnutrition
Irradiation injury
Gigantism
First 3 - Deficiency in cell proliferation and/or matrix synthesis
Gigantism - Increased cell proliferation
What is an example of a disease in the hypertrophic zone of the epiphyseal plates?
Rickets
Osteomalacia
Insufficiency of calcium or phosphate for normal calcification
What is an example of a disease in the metaphysis zone of the epiphyseal plates?
Osteomyelitis - Bacterial infection
Osteogenesis imperfecta - Abnormality of osteoblasts and collagen synthesis
Scurvy - Inadequate collagen turnover
What does normal development of bone require?
– Calcium
– Phosphorus
– Vitamins A, C and D
– Balance between growth hormone, thyroid and parathyroid hormones, oestrogen and androgens
What factors should be considered in describing mechanism of injury of a broken bone?
Direction of force
– Direct v angular
– Rotational
– Compression
Energy transfer
– Cause
– Site
What can imaging tell you about a damaged bone?
Site & bones involved Clues on soft tissue injury Clues on energy transfer: – Wide displacement – Comminuted – Multiple fracture sites Pathological bone Paediatric bone
What is the definition of a fracture?
A complete or incomplete break in a bone
How should you describe a fracture?
Site Open to surface Contaminated Associated soft tissue injury Joint involvement Number of pieces Alignment Degree of separation
Name some fracture patterns yo
Traverse
Linear
Oblique non-displaced
Oblique displaced
Spiral
Greenstick
Comminuted
What is an avulsion fracture?
– a fragment of bone is separated from the main mass
What is a buckled fracture?
– a.k.a. impacted fracture, torus fracture
– ends are driven into each other
– commonly seen in arm fractures in children
What is a compression or wedge fracture?
– usually involves the vertebrae
What is a pathologic fracture?
– caused by a disease that weakens the bones
What is a stress fracture?
– hairline crack
What are some limb threatening or non-union risks?
– Dislocation – Comminuted – Compound – Compartment syndrome – Vascular / nerve injury – Significant soft issue injury – Pathological bone
What are ‘bone remodelling units’?
– Consist of osteoclasts and osteoblasts
– Keep adult bone mass relatively constant in the face of developmental, physiological and physical demands
Discuss bone growth, remodelling and fracture repair
Depends on the activity of the cells of the periosteum
‘Bone Remodelling Units’
– Consist of osteoclasts and osteoblasts
– Keep adult bone mass relatively constant in the face of developmental, physiological and physical demands
Bone has a remarkable capacity to heal well (unlike articular cartilage).
Discuss bone healing following a fracture
Fracture healing depends on the activity of osteoblasts in the local periosteum
Takes 2 -20 weeks for healing, depending on:
– Severity and position of the fracture
– Age of the patient
What are the three major phases of fracture healing?
- Reactive Phase
- Reparative Phase
- Remodelling Phase
Discuss the reactive phase of fracture healing
- Fracture and inflammatory phase (haematoma)
* Fibroblasts in the periosteum proliferate to form granulation tissue around the fracture site
Discuss the reparative phase of fracture healing
- Callus formation-osteoblasts quickly form woven bone, to bridge the gap
- Woven bone is weak as the collagen fibres are arranged irregularly
- Lamellar bone laid down-collagen organised in regular sheets to give strength and resilience
Discuss the remodelling phase of fracture healing
• Remodelling by osteoclasts to restore original bone shape
What are the treatments available for fractures?
Conservative – Simple fracture with low risk of non-union – Dependent on natural healing process – +/- immobilisation – Rehabilitation
Intervention
– Fractures with limb threat or risk of non union
– Augment natural healing with replacement or strengthening
– +/- immobilisation
– Rehabilitation
What are the learning outcomes?
Recall the processes involved in endochondrial ossification
Recall the differences between a primary and secondary ossification centre
Recognise that disease and damage to the epiphyseal plate will affect bone growth
Classify different types of fracture patterns Describe the process of fracture healing
