Fracture Management 101 Lecture Flashcards
What are the two types of bone
Cortical: hard bit that makes up the outer cortex of bones, in direct contact with the periosteum
Cancellous: spongy woven in the middle + metaphyseal areas
What is the microscopic structure of cortical bone
Have closely packed osteons which contain:
- Central canal called the haversion canal: contains blood vessels, nerves and lymphatic vessels
- These vessels and nerves branch off at right angles through a perforating canal/Volkmann’s canals to extend to the periosteum and endosteum
- Surrounded by concentric rings (lamellae) of matrix and collagen fibers
- Between the lamellae are osteocytes in spaces called lacunae
- Canaliculi connect with canaliculi of other lacunae and the central canal which allows nutrients to be transported to the osteocytes and wastes removed
What is the microscopic structure of cancellous bone
- Also contains osteocytes in lacunae but they aren’t arranged in concentric circles
- Instead they’re in a lattice network of matrix spikes called trabeculae
- Trabeculae are covered by the endosteum which can readily remodel them
- Trabeculae form along lines of stress to direct forces out to the more solid compact bone to provide more strength and balance
- The spaces in some cancellous bone contains the bone marrow
What is the macroscopic anatomy of long bones
Two main regions = diaphysis and epiphysis
- Each epiphysis meats the diaphysis at the metaphysis and during growth this area contains the epiphyseal plate where long bone growth occurs –> becomes the epiphyseal line in adults
- Lining the inside of the bone adjacent to the medullary cavity is the endosteum which contains osteogenic cells and osteoblasts
- On the outside of bones is the double layered periosteum adjacent to cortical bone and covered by an outer fibrous layer of dense irregular connective tissue
- The periosteum covers the whole outside of bones except where the epiphysis meets other bones –> covered with articular cartilage
What is inside the diaphysis?
The medullary cavity filled with yellow bone marrow in adults
What is the epiphysis filled with?
Cancellous bone
Some long bones have red bone marrow filling the spaces of the cancellous bone
What is the epiphyseal plate and what does it become in adulthood?
The epiphyseal plate occurs at the metaphysis where the diaphysis meets the epiphys
Where long bone elongation occurs during growth until 18/21
Becomes an epiphyseal line in adulthood
What is the endosteum?
The lining of the inside of bone adjacent to the medullary cavity
Made of osteogenic cells and osteoblasts to grow, repair and remodel bones. Also has osteoclasts
What is the periosteum?
The double layered structure on the outside of bones
- Outer layer is dense irregular fibrous tissue
- Inner cellular layer contains osteoclasts for bone resorption and osteoblasts
- Contains blood vessels, nerves and lymphatic vessels to nourish cortical/compact bone
- Tendons and ligaments attach to bone via the periosteum
What makes up the ends of bones?
Articular cartilage (hyaline cartilage)
What is an osteoblast?
Forms new bone
- Found in the endosteum and the cellular layer of the periosteum
- No mitotic activity (don’t divide)
- Synthesise and secrete collagen matrix –> matrix calcifies and traps the osteoblast –> becomes a mature osteocyte
What is an osteocyte?
The mature primary cell of bone
- Found in lacunae
- Maintain the mineral concentration of the matrix via the secretion of enzymes
- No mitotic activity
- Communicate with other osteocytes and receive nutrients via long cytoplasmic processes that extend through the canaliculu
What are osteogenic cells?
- The only bone cells that divide –> have a high level of mitotic activity
- They differentiate and develop into osteoblasts
What are osteoclasts?
The cells responsible for bone breakdown/bone resorption
- Multinucleated
- Originate from monocytes and macrophages
- Found in the endosteum and the cellular layer of the periosteum
What are the two types of bone healing?
Primary bone healing and secondary bone healing
What is primary bone healing
- Fracture is absolutely stable
- Ends of bones are opposed
- Bone heals directly
- Absence of callus
- Osteoclasts break down the bone and the howship’s lacuna drag osteoblasts behind them to form new bone
What is secondary bone healing?
- Where you have more than 10% of movement within the fracture site
- Inflammation: week 1
- Break, haematoma released outside periosteum, inflammatory cytokines released (IL-1, IL-6, TNFa), recruit pro-inflammatory cells, increase blood supply - Soft callus: weeks 2-3
- Cartilage framework between bones inside the periosteum
- You can see this on X-Ray - Hard callus: weeks 4-12
- Development of cancellous bone across bridge (osteoblastic action)
- Fracture relatively stable now, can come out of cast - Remodelling: months to years
- Becomes more linear osteons within in the cancellous bone
Describe this X-Ray
I have an AP and Lateral radiograph from a 65yo F who fell off a roof. The most obvious finding is a simple left radius fracture of the distal metaphysis. It is extra-articular and a closed fracture. Nil displacement but dorsal angulation.
First articular arthritis.
Osteoporosis or osteopenia.
There is swelling around the fracture site.
What are the principles of stability?
- Absolute stability: primary bone healing
- compression plating, lag screws, tension band wire - Relative stability: secondary bone healing
- Intramedullary nail, external fixation - Load sharing: weight bearing through construct and bone
- Load bearing: weight bearing through construct only
What is the Gustilo-Anderson Classification?
Applied to any open fractures/wounds
I. <1cm wound (puncture)
II. 1-10cm wound + minimal soft tissue damage
III: >10cm would + severe tissue damage
IIIC: need theatre urgently, have some sort of high contamination risk, neurovascular compromise etc
How do you classify paediatric fractures?
Salter Harris Classification: injuries involving the epiphyseal plate
II = most common
What are insufficiency fractures?
Osteoporotic bone + a non-traumatic event
- Usually spine + pelvis
- Need to treat the underlying condition
- Very rarely need surgery
