Podcast
Questions and Answers
What is the main cause of a pathological fracture?
What is the main cause of a pathological fracture?
Which classification type describes fractures based on the direction of the fracture line?
Which classification type describes fractures based on the direction of the fracture line?
What distinguishes a greenstick fracture from other types of fractures?
What distinguishes a greenstick fracture from other types of fractures?
Which term refers to fractures classified according to the number of fracture lines?
Which term refers to fractures classified according to the number of fracture lines?
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What are the significant classifications for fractures based on location?
What are the significant classifications for fractures based on location?
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What are the main cells involved in bone composition?
What are the main cells involved in bone composition?
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Which type of bone is primarily composed of osteons?
Which type of bone is primarily composed of osteons?
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Which best describes the role of sesamoid bones?
Which best describes the role of sesamoid bones?
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What type of bone is primarily found at the ends of long bones?
What type of bone is primarily found at the ends of long bones?
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Which of the following correctly states the composition of bone?
Which of the following correctly states the composition of bone?
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What type of fracture resembles a folded cardboard tube?
What type of fracture resembles a folded cardboard tube?
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Which fracture type is characterized by the displacement of fragments under stress?
Which fracture type is characterized by the displacement of fragments under stress?
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What is the process by which woven bone matures to lamellar bone called?
What is the process by which woven bone matures to lamellar bone called?
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Which mechanism is involved in the formation of most flat bones?
Which mechanism is involved in the formation of most flat bones?
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What is a cominuted fracture?
What is a cominuted fracture?
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What classification refers to a fracture that remains stable after reduction?
What classification refers to a fracture that remains stable after reduction?
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Delayed unions, non unions, and malunions refer to complications seen in which process?
Delayed unions, non unions, and malunions refer to complications seen in which process?
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Which type of fracture is categorized by a large difference in energy and soft-tissue injury?
Which type of fracture is categorized by a large difference in energy and soft-tissue injury?
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An impacted fracture occurs when:
An impacted fracture occurs when:
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Which classification indicates fractures at multiple levels or involving multiple bones?
Which classification indicates fractures at multiple levels or involving multiple bones?
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What type of fracture is formed mainly through torsion forces?
What type of fracture is formed mainly through torsion forces?
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What does a score of grade 3C indicate regarding bone injury?
What does a score of grade 3C indicate regarding bone injury?
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In the inflammatory phase of indirect bone healing, which cells are primarily involved?
In the inflammatory phase of indirect bone healing, which cells are primarily involved?
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What is a characteristic of direct healing in bone repair?
What is a characteristic of direct healing in bone repair?
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What type of healing occurs when the fracture gap is less than 0.8mm?
What type of healing occurs when the fracture gap is less than 0.8mm?
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Which statement about the remodelling phase of bone healing is accurate?
Which statement about the remodelling phase of bone healing is accurate?
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Which of the following best describes primary bone union?
Which of the following best describes primary bone union?
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What is the difference between primary and secondary healing?
What is the difference between primary and secondary healing?
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During which phase of indirect healing is granulation tissue formed?
During which phase of indirect healing is granulation tissue formed?
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What is the primary means of growth for long bones?
What is the primary means of growth for long bones?
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Which zone of the growth plate contains normal hyaline cartilage?
Which zone of the growth plate contains normal hyaline cartilage?
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What happens after osteoblasts become encased in the extracellular matrix?
What happens after osteoblasts become encased in the extracellular matrix?
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What type of bone is initially formed during intramembranous ossification?
What type of bone is initially formed during intramembranous ossification?
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What is formed in the zone of hypertrophy and calcification?
What is formed in the zone of hypertrophy and calcification?
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What characterizes the secondary ossification centres?
What characterizes the secondary ossification centres?
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In endochondral ossification, what role do osteoclasts play?
In endochondral ossification, what role do osteoclasts play?
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During what process does the bone replace the removed cartilage?
During what process does the bone replace the removed cartilage?
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What does Wolff's law state about bone?
What does Wolff's law state about bone?
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Which imaging technique is NOT typically used for diagnosing fractures?
Which imaging technique is NOT typically used for diagnosing fractures?
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What type of fracture is typically caused by distraction or tension forces?
What type of fracture is typically caused by distraction or tension forces?
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Which statement accurately describes the effect of loading rate on fractures?
Which statement accurately describes the effect of loading rate on fractures?
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What phenomenon occurs when electric currents are induced in bone during stress?
What phenomenon occurs when electric currents are induced in bone during stress?
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Which of the following is a symptom indicative of a bone injury?
Which of the following is a symptom indicative of a bone injury?
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Which type of fracture typically results from torsion forces?
Which type of fracture typically results from torsion forces?
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What factor influences the toughness of a bone and its ability to absorb energy?
What factor influences the toughness of a bone and its ability to absorb energy?
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Study Notes
Approach to Fractures
- This presentation covers the approach to fractures, specifically bone structure, function, development, diagnosis, different forces, types, classification, healing, and repair methods.
Learning Objectives
- Students should be able to describe normal bone structure and development.
- Students should be able to classify fractures according to type, location, and nature.
- Students should be able to explain primary and secondary bone healing.
- Students should be able to discuss the principles of fracture repair.
- Students should be able to identify delayed unions, nonunions, and malunions.
Bone Structure
- Bone is composed of cells and organic/mineral matrix.
- Cells include osteoblasts (make bone), osteocytes (bone cells), and osteoclasts (resorb bone).
- Organic matrix (⅓ of bone mass) includes collagen fibers and proteoglycans.
- Mineral matrix (⅔ of bone mass) includes calcium phosphate as hydroxyapatite.
- Bone types include long bones (epiphysis, physis, metaphysis, diaphysis), short bones (carpus/tarsus), sesamoid bones (usually in or adjacent to tendons), flat bones (skull/scapula), irregular bones (vertebrae), and non-flat bones of the skull (zygomatic arch).
Bone Function
- Axial skeleton: Provides structure for the skull, hyoid apparatus, vertebral column, ribs, and sternum. Also protects organs in the cranial and thoracic cavities.
- Appendicular skeleton: Includes the thoracic and pelvic limbs.
- Heterotopic skeleton: Includes the os penis.
Bone Development
- Initially bone develops as woven bone (immature) and is then replaced by lamellar bone (mature).
- Lamellar bone has two types: compact cortical bone (made up of osteons) and spongy/cancellous bone (made up of trabeculae, found in ends of long bones and inner layers of long bones and vertebrae).
- Intramembranous ossification: Formation of bone directly from osteogenic mesenchymal cells (most flat bones). Periosteal cells increase the width of long bones.
- Endochondral ossification: Formation of bone from a cartilage precursor (vertebrae, ribs, sternebrae, pelvis, and the primary means of long bone growth). Prominences on the long bones may have separate centres of ossification.
Bone Development: Endochondral Ossification - Primary Centre
- Chondrocytes form columns characterized by resting/reserve zone (normal hyaline cartilage), proliferation zone (chondsrocytes multiply), hypertrophy and calcification zone (chondrocytes grow and matrix mineralises),
- cartilage erosion zone(chondroclasts remove matrix, and blood vessels invade), and endochondral ossification (bone replaces removed cartilage, bone elongation occurs).
Bone Development: Secondary Centres
- Separate ossification centres arise in epiphyseal areas.
- These centres enable localized joint and bone shaping.
- They contain their own blood supply which doesn't cross the growth plate.
Modelling
- Wolff's law states that bone responds to the loads placed upon it.
- Bone and cartilage need load to remain healthy.
- When bone is loaded, piezoelectric effects induce electric currents.
- Electropositivity on convex surfaces leads to osteoclastic activity.
- Electronegativity on concave surfaces leads to osteoblastic activity.
- Trabeculae/struts/plates form in line with applied forces.
Types of Fractures
- Various types include monotonic (supramaximal loading), pathological (weakened by disease), and stress fractures(accumulation of fatigue damage exceeding body's remodelling ability).
Classification of Fractures
- Based on location (general-articular, epiphyseal, metaphyseal, diaphyseal; special-condylar, trochanteric), displacement (greenstick, folded, fissure, depressed, compression, impacted, complete, incomplete), direction (transverse, oblique, spiral, comminuted), number of fracture lines (multiple, comminuted), stability (stable, unstable), and open vs. closed (Gustilo-Anderson classification).
Bone Healing: Phases
- Inflammatory/hematoma phase: Hemorrhage, neutrophils/macrophages, growth factors.
- Reparative/granulation/callus formation phase: Granulation tissue, vascularisation, collagen fibers, chondrogenesis, gradual mineralisation.
- Remodelling phase: Woven bone replaced by lamellar bone.
Bone Healing: Direct vs. Indirect Healing
- Direct Bone Healing: Primary bone union, occurs under rigid fixation, no callus formation.
- Gap healing: Bone ends less than 0.8 mm
- Contact healing: Bone ends less than 0.01 mm, Haversian remodelling begins immediately
- Indirect Bone Healing: Secondary bone union, callus formation.
Fracture Repair and Aims
- Aims to rehabilitate patient as quickly as possible, achieving sufficient reconstruction to meet functional requirements.
- Fixation needed for immobilisation until healing occurs, and mobilization of joints, with respect to stability/instability of each fracture type in different patients.
- Biomechanics of Repair: Prevent rotation, prevent bending, maintain length, and withstand distraction forces.
- Repair Methods: Conservative, closed reduction with external fixation, open reduction without rigid fixation, rigid external fixation, open reduction with internal fixation, and closed reduction with internal fixation.
Tools and Methods of Fixation
- Tools: Cast/splints, External fixators, Intramedullary pins, Screws, Plates, Wire.
Conservative Approach for Pelvic Fractures
- Pelvic fractures are inherently stable.
- Surgical fixation is considered if the integrity of the weight-bearing axis is lost, the pelvic canal is narrowed, or there is an acetabular fracture, bilateral sacroiliac separation, intractable pain, or multiple injuries.
- Medical considerations include iliac fractures with minimal displacement, ischial fractures, public fractures, and cost prohibitions to surgery.
Fracture Repair Methods: Casts and Splints
- Stable fractures (distal limbs, diaphyseal, single bone, paired bone, simple and uncomplicated fractures in young dogs).
- Considerations: Pressure sores, patient interference, change of cast affecting fracture site, joint stiffness, cost.
Fracture Repair Methods: Rigid External Fixation
- Linear and circular fractures; may be open or closed.
- Multiple configurations, biomechanically strong dynamic repair.
- Wound management is necessary, along with considerations for owner compliance, patient interference, drainage tracts, and soft tissue injury.
Fracture Repair Methods: Screws
- Types include self-tapping vs non-self-tapping, cortical vs cancellous.
- Techniques such as lag screws, plates, and locking plates are used to provide stabilisation and structural integrity.
Fracture Repair Methods: Plates
- Plates can be applied in various ways neutralisation, compression, buttress, and bridging to overcome forces at the fracture site and stabilize the fracture during healing.
- Neutralization overcomes bending, rotation, and shear forces.
- Compression, Buttress, and Bridging support under compressive forces and span bone gaps to ensure stability.
Fracture Repair Methods: Wire
- Cerclage wire: encircles bone, used for some mandibular/maxillary, and long oblique fractures to compress and provide stability.
- Tension band wire: used for neutralising avulsion forces (tendons, ligaments) by applying vector forces to coapt the fracture site.
Fracture Repair Methods: Pins
- Pins are generally inexpensive and simple to use.
- Are often used for diaphyseal fractures, as they easily neutralise bending forces.
- Cannot resist rotation, axial collapse, or distraction.
- May be supplemented with interlocking nails or external fixators to overcome these limitations.
Fracture Repair: Planning
- Evaluation of patient type, and characteristics of the fracture, location, direction, stability, complications, and species/breed, age, activity, expertise, and budget.
Treatment Considerations
- Carpenter vs. Gardener: Preservation of soft tissue envelope and temporary extraosseous blood supply is important.
- Challenges: Open fractures pose higher risks of infection and joint problems. Young animals may be difficult for owners to manage.
Fracture Complications
- Delayed union (fracture takes more time to heal).
- Non-union (fracture does not heal).
- Subtypes: Viable, non-viable.
- Different causes for different types.
Fracture Assessment Score
- Mechanical, Biological, Clinical factors are evaluated.
- Mechanical: Strength of fixation required.
- Biological: Healing rate.
- Clinical: Patient/client factors considered.
Problems with Healing
- Mechanical failure: Poor blood supply, soft tissue coverage, and systemic disease.
- Biological failure: Poor blood supply, soft tissue coverage, and systemic disease.
- Clinical failure: Poor owner compliance.
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Description
This quiz examines the comprehensive approach to fractures, including bone structure, development, diagnosis, and healing methods. Students will learn about different types of fractures, how to classify them, and key principles of fracture repair. Familiarity with normal bone structure, delayed unions, and nonunions will also be assessed.
