Fracture Healing Flashcards
Describe the features of cortical/compact bone [2]
- Slow turnover rate/metabolic activity
- High Young’s modulus:
- i.e. resistance to torsion and bending
Describe the features of cancellous/spongy/trabecular bone [3]
- Higher turnover rate and undergoes greater remodelling
- Low Young’s modulus
- more elastic
Describe the cellular components of bone [6]
- Osteoblasts
- produce new bone under the influence of parathyroid hormone (PTH)
- Osteocytes
- 90% of the cells in mature bone.
- maintains extracellular calcium levels
- Osteoclasts
- resorbs bone
What is the physis? [2]
What does it allow after a fracture? [1]
What happens if physeal blood supply is damaged? [1]
- Unique feature of children’s bone that is responsible for skeletal growth
- Allows remodelling of angular deformity after fracture
- If physeal blood supply damaged, will lead to growth arrest (either partial or complete)
What are the functions of bone? [5]
- Structural
- Support
- Protection
- Movement
- Mineral Storage
- Calcium
- Phosphate
Define indirect bone healing [2]
- Secondary bone healing, via callus formation
- Formation of bone via a process of differential tissue formation until skeletal continuity is restored
Name the 4 stages of indirect fracture healing [4]
- Fracture haematoma and inflammation
- Fibrocartilage (soft) callus
- Bony (hard) callus
- Bone remodelling
Describe the stages of indirect fracture healing under the following headings:
- fracture haematoma and inflammation [3]
- fibrocartilage (soft) callus formation [4]
- bony (hard) callus formation [2]
- bone remodelling [2]
-
Fracture haematoma and inflammation
- occurs 6-8hrs after injury
- blood from broken vessels forms a clot.
- swelling and inflammation to dead bone cells at fracture site
-
Fibrocartilage (SOFT) callus
- (lasts about 3 weeks)
- new capillaries organise fracture hematoma into granulation tissue forming the procallus
- fibroblasts and osteogenic cells invade procallus and make collagen fibres which connect ends together
- chondrocytes begin to produce fibrocartilage
-
Bony (HARD) callus
- (after 3 weeks and lasts about 3-4 months)
- osteoblasts make woven bone
-
Bone Remodeling
- osteoclasts remodel woven bone into compact bone and trabecular bone
- at this point, there is often no trace of fracture line on X-rays
Describe the features of direct bone healing [5]
- Unique ‘artificial’ surgical situation
- Direct formation of bone, without the process of callus formation, to restore skeletal continuity
- Fracture stable
- No movement under physiological load
- Relies upon compression of the bone ends and direct formation of bone via osteoclastic absorption and osteoblastic formation (cutting cones)
List the factors that can compromise blood supply to a bone and inhibit fracture healing [13]
- Surgical factors
-
Anatomical factors (some fractures are more prone to problems with fracture healing e.g.)
- proximal pole of scaphoid fractures
- talar neck fractures
- intracapsular hip fractures
- surgical neck of humerus fractures
-
Patient Factors
- increasing age
- diabetes
- anaemia
- malnutrition
- peripheral vascular disease
- hypothyroidism
- smoking
- alcohol
What 3 medications can inhibit bone healing? [3]
- NSAIDs
- Steroids
- Bisphosphonates
How do NSAIDs affect fracture healing? [2]
- Reduce local vascularity at fracture site
- Additional reduction in healing effect independent of blood flow
How do COX-2 inhibitors affect fracture healing? [2]
- COX-2 NSAIDS inhibit fracture healing more than non-specific NSAIDS
- Magnitude of effect is related to duration of treatment
How do bisphosphonates affect fracture healing? [2]
- Inhibit osteoclastic activity which delays fracture healing as a result
- Has a long half life
