Fracture Objectives- Dr. Huck Flashcards
What appendicular bone cannot be repaired with an interlocking nail and why?
Radius. Because of the curvature of the radius. Interlocking nail would displace the fracture.
What are the primary benefits of external skeletal fixation compare to plating ?
- Can be placed with minimal disruption of the fracture fragments
- Useful for treatment of grade II and III open fractures
- Implants can be removed in stages to increase the loading on the bone- Wolff’s Law
- Low cost compared to internal fixation devices.
Basic guidelines for placement of trans- fixation pins.
Clamps connecting the pins and rods should be at least ______cm away from skin.
1 cm
What fractures are not amenable to external coaptation?
Never cast an OPEN FRACTURE or if it involves a JOINT.
What is the most common complication associated with open fractures?
Osteomyelitis.
What complications are associated with external skeletal fixation?
- Pin tract drainage
- Loosening or pins and wires
- Osteomyelitis
- Ring sequestrum
- Nerve or vascular damage
The following are describes of which type of internal fixation approach:
- Primary bone healing
- Perfect bone reconstruction
- Rigid fixation with compressions at bone ends
- REQUIRED FOR ARTICULAR FRACTURES: transverse, oblique, segmental fractures.
Open Anatomic Reduction/ Reconstruction
Difference between yield point and failure point on a stress-strain curve for any material.
Yield point: when the material begins to deform __________. Occurs between _________ and ____________ deformation. Permanently deformed.
Failure point: material cannot withstand anymore ______ and fails.
Yield point: when the material begins to deform PLASTICALLY. Strain exceeds the materials ability to recover, rendering it permanently deformed. Occurs between ELASTIC and PLASTIC deformation.
Failure point: material cannot withstand anymore STRAIN and fails.
Retrograde or Normograde?
Pin placed coming distally
Retrograde
Why is Wolff’s law important when considering fracture fixation?
Bone remodels based on the forces that are applied. When there are increased forces(weight bearing) the bone remodels and thickens. But if there are decreased forces(non-weight bearing) the bone resorbs and weakens.
In simpler terms: Weight bearing is important so bone will remodel and will not reabsorb over the line leading to osteopenia.
When is dynamization best applied with regards to the timing of fracture healing?
~ 6 weeks post repair
Callus must be present to achieve benefits of dynamization
What percentage of the intramedullary canal should be filled if this is the primary source of fixation.
With cerclage: 70% canal fill
With plate: 35-40% canal fill
Pros and cons of internal fixation vs. external coaptation.
The following are disadvantages for ________:
- requires frequent rechecks and bandage changes
- only for specific fractures
- risk of bandage morbidity preventing continued use
- immobilized joints
External coaptation
Difference between elastic and plastic deformation.
Elastic: ____________change in shape.
Plastic: ___________change in shape.
Elastic: REVERSIBLE
Plastic: PERMANENT
Difference between stress and strain.
Stress(cause or effect): external ________ applied to any cross sectional area.
Strain(cause or effect): _________ of a loaded material as compared to its original form. Measured in length.
Stress is the CAUSE: External FORCE applied to any cross sectional area.
Strain is the EFFECT: DEFORMATION of a loaded material as compared to its original form
How is a lag screw used in fracture repair?
Tightening the screw pulls the trans cortex closer to the cis cortex causing COMPRESSION across the fracture.
Difference in severity between the various open fracture grades.
Which type of fracture is seen commonly with bite wounds? There is mild soft tissue trauma without extensive soft tissue damage. This open wound is >1cm in size.
Type II
What lends the most strength to tension band fixation?
Figure 8 wire between hole and pin
What is unique about buttress plating compared to other plating modes?
Most or all screw hols should be filled.
No as stable because the main force of the one is going along the fracture like so when the animal bears wight the fracture wants to distract.
Which screw, lag or position, provides more stability?
LAG provides more stability than a position screw.
Normograde or Retrograde?
Pin placement beginning proximally
Normograde
What plate types can be used to achieve compression of a fracture?
Dynamic Compression Plates (DCP)
Limited Contact Dynamic Compression Plates (LC-DCP
Locking Compression Plates (LCP)
Why would someone choose to utilize a skewer pin in conjunction with a cerclage wire?
For use in SHORT oblique fractures. To aid in maintenance of reduction and promote compression across the fracture line.
How does the use of dynamization promote bone healing?
Allows increased axial loading of the fracture to enhance callus hypertrophy and remodeling of the fracture.
What are the 4 factors that should be considered when choosing implants for fracture fixation?
- Fracture type and location
- Bone affected
- Patient factors
- Surgeon preference and experience
Pros and cons of internal fixation vs. external coaptation.
The following are disadvantages of _______:
- expense to clinic and owner: lots of specialized equip and inventory required
- Requires training
- May require 2nd sx for explanation
Internal Fixation
When might it be necessary to remove implants?
Cold temperatures, infection, obvious pain from the patient.
What forces are neutralized with the application of an intramedullary pin?
Resist BENDING forces only
Basic rules/guidelines for plate fixation of fractures.
What type of plate(conventional or locking) needs minimal to no contouring?
Locking
Stable repair requires screws at least 4 cortices above and below fracture.
Principle for applying cerclage wire to a fracture.
How far apart from the fracture ends should the wire be placed?
Place 0.5cm from fracture ends, spaces ~ 0.5-1.0x bone diameter apart
Compresses the surfaces effectively while preserving some of the soft tissue attachments to the fragments.
Why must conventional plates(LC-DCP)be perfectly contoured to the bone on which they are applied?
Allows stress to be more evenly distributed across plate(less stress at screw hole)
Less contact with bone = less disruption of periosteal vascularity
Goals of fracture fixation.
Restore ______ and _______ to promote bone healing and limb function.
Restore LENGTH and ALIGNMENT to promote normal bone healing and limb function.
Name that salter harris fracture.
Articular fracture that runs though the epiphysis, across the physis, and through the metaphysis.
Type IV
Pros and cons of internal fixation vs. external coaptation.
The following lists advantages for internal or external?
- Variery of fixation options to promote stable repair.
- Can promote normal muscle/joint function during bone healing
- Fewer rechecks
Internal Fixation