Fracture healing Flashcards
What are principles of fracture fixation?
*Size limitation
*Post op care challenges
-equines need to stand
-farm species staying clean
-small animals staying still
What are the different forces of fracture?
*Bending
*Torsion
*Compression
*Tension
*Shearing
Why + how do fractures occur? - direct trauma
– The force is applied at or near to the point of fracture.
– The degree and direction of the force determine the fracture pattern
Why and how do fractures occur? - intrinsic fractures?
– Pathological fractures
* Local disease
–neoplasia
* Systemic disease
–osteopenia
–hyperparathyroidism
(renal/nutritional)
– Repetitive loading
* Stress fractures
What are the different fracture lines?
*Transverse
*Oblique
*Spiral
*Comminuted - fragments
*Segmental
What is the blood supply to fractured bone?
– + Extraosseous arteries
– From tissues around the fracture
– Can be disturbed by fixation
method
What are the conditions needed for primary bone healing?
*absolute stability
*Direct contact = gap <0.01mm
*Direct contact-ish (GAP) = gap <1mm
*Strain below <2%
Which primary bone healing will take longer? Contact / gap
Contact
What will not form with primary bone healing?
Callus
What are the conditions for secondary bone healing?
*Gap more than 1mm
*Strain more than >2%
*Callus will form
*Rapid bone healing
What is the pathogenesis of secondary bone healing?
1.Haematoma formation
2.Fibrocartilaginous callus formation - haematoma forms into matrix
3.Bony callus formation - matrix mineralises into spongy bone
4. Bone remodelling - fracture site wider due to callus formation
What are the risk factors of fracture?
*Old patient
*Poor health
*Poor soft tissue envelope
*Cortical bone (compared to cancellous bone)
*High velocity injury
*Extensive approach
What are the complications of fracture healing?
*If failure of fracture to heal in time / manner expected
-infection
-instability - unsuitable fixation
-implant failure
-Vascular compromise
When can external coaptation be used? (casts, splints + bandages)
*Small/ medium sized young dogs
*Diaphysis of long bones
*Simple closed fractures
*Distal limb
What are the advantages of intra-medullary pins?
– Good at resisting bending
– In neutral axis of bone
– Often relatively inexpensive
– May be used with other fixation devices
What are the disadvantages of intra-medullary pins?
– Poor at resisting rotation
– Poor at resisting shear
– Interferes with medullary blood supply
– Difficult in chondrodystrophic dogs
When is cerclage wire used? What are the potential problems of using it?
– Used in combination with IM pins for long oblique fractures
– Must be tight to provide compression
* 1* bone union
– Can slip along diaphysis
* Femur/humerus v tibia
* Causes vascular damage
What are different types of screws used?
*Cortical screw
*Cancellous screw
*Shaft screw
*Self-tapping Cortical screw
What are the uses of positional screws?
- To maintain relative position of two bone fragments
- To hold plate to bone
- To anchor wire or suture to bone
What type of screw is most efficient method of creating compression?
Lag screw
What are the advantages of using plates?
–Negate all the fracture forces
–Different varieties to fit different fractures
–Internal fixation
What are the disadvantages of using plates?
*Costly
*Expertise needed
What are the advantages of external skeletal fixation?
- Negates all the fracture forces
- Rigid fixation with minimal invasion of injured area
- Allows access to open wounds during fracture repair
- Can maintain limb length, if bone defects exist, while secondary bone healing occurs
- allows for gradually increasing loads to be applied to the healing bone
- Materials are inexpensive
What are the disadvantages of external skeletal fixation?
- High complication rate
- Iatrogenic interference
- Catches on clothing/furniture
- Pin tract infections
- Can weaken/loosen over time
What are the principles of articular fractures?
- Articular fractures are common
– E.g. single humeral condylar fractures - Require primary bone healing
– Accurate reduction
– Require rigid fixation - Early return to full function
– Physiotherapy
– Range of motion
– Avoid atrophy of joint tissues
