MSK 3 ESF Fracture healing plates Flashcards
What are the four main types of Linear ESFs?
- Type 1a – half pins from 1 side of bone only – uniplanar
- Type 1b – 2 x Type 1a – biplanar unilateral
- Type 2 – full pins and connecting bars each side of the bone - uniplanar and bilateral
- Type 3 – combination of Type 2 and Type 1a, strongest and stiffest.
What factors influence the choice of ESF type on the tibia?
Soft tissue structures are mostly caudal and lateral on the bone, while the craniomedal aspect is superficial with little soft tissue coverage, making it ideal for pin placement.
Type 1a and 1b are commonly used in tibias.
List ways to maximize the pin/bone interface.
- Pin Type: threaded > smooth pins
- Pin size: threaded portion 20-30% of bone diameter
- Pin placement: central placement through widest part of the bone available
- Appropriate pre-drilling – drill hole 0.1mm smaller than pin
- Low speed insertion <300rpms
- Proper insertion force
How can stability be increased in pin configurations?
- Correct number of pins: 3-4 per fragment
- Decrease the pin working length; place clamp with bolt no more than 1cm from skin
- Pin configuration/frame stiffness – far-near-near-far pin placement
- Consider multiplanar frames
- Consider augmentation with articulations, diagonals, + IM pin or IN
Explain the concept of staged disassembly in EFS.
Staged disassembly is used in some fractures to avoid disturbing the hematoma necessary for bone formation while allowing for progressive destabilization to increase bending strength over time.
Timing and degree of destabilization depend on patient biology, fracture mechanics, and logistical factors.
What are the pros of ESF placed closed?
- Maintains biological envelope, preserving the hematoma
- Reduces damage to local blood supply
- Flexibility in pin placement
- Frame can be removed in a staged fashion
- Open wounds can be managed daily
- Always accessible and adjustable
- Frequent adjustments for limb deformities
- No long-term implant irritation
What are the cons of ESF placed closed?
- Increased risk of infection
- Large bending forces on fixation pins
- Not intended for long-term use
- Holes of pins may create areas of weakness
- Requires diligent management
- Can cause discomfort to the patient
What are the pros of closed plating with DCP in bridging fashion?
- Takes all load sharing across the fracture
- Reduced risk of healing complications
- More comfortable for the patient sooner
What are the cons of closed plating with DCP in bridging fashion?
- More damage to biology/blood supply
- Implant can act as a nidus for infection
- Risk of catastrophic fracture if improperly sized or positioned
What are the key steps in surgical approach to acetabular fracture for key exposure?
- Osteotomy of the greater trochanter
- Incise joint capsule + additional incision parallel to acetabular rim
- Use bone holding forceps for lateral distraction of the proximal femur
- Use Kern bone holding forceps to hold the ischial tuberosity
Define neutralization plating.
Plates that neutralize bending and rotational forces to protect lag screw fixation, often used after lag screws reduce an oblique diaphyseal fracture.
What is bridge plating?
Plates that bridge across multifragmentary long bone fractures, providing relative interfragmentary stability without disturbing the fracture site.
What is buttress plating?
Also known as anti-glide plates, used to supplement lag screw fixation of metaphyseal shear or split fractures.
How does a bone screw lock into a plate?
Locking screws engage with a thread on the plate, allowing for fixed angle stability without relying on bone/plate contact.
What is the mechanism of load transfer for locking plates compared to conventional non-locking plates?
Load is transferred through the entire construct in locking plates, while non-locking plates rely on frictional force between the bone and plate.
What are the indications for stabilizing pelvic fractures in cats?
- Not weight bearing
- Articular fractures
- Narrowing of the pelvic canal by 50% or more
- Bilateral fractures
- Pubic fracture repair with prepubic tendon avulsion
- Worsening displacement on sequential radiographs
What is the function of the lumbosacral trunk in pelvic injuries?
It becomes the sciatic nerve, and its function can be evaluated through the withdrawal reflex.
What are the principles of articular fracture repair?
- Accurate anatomical reduction
- Rigid fixation
- Early mobilization
What are the advantages of using an IM pin and plate?
- Minimally invasive technique
- Reduced cost of IM pin
- Increased stability
- Reduces plate strain
- Improves overall stiffness of construct
- Establishes bone length
What are the disadvantages of using an IM pin and plate?
- Disrupts fracture hematoma
- Migration risk of IM pins
- Potential sciatic nerve damage
- Difficult removal in case of infection
What is the difference between normograde and retrograde application of an IM pin?
Normograde: pin starts outside the bone; Retrograde: pin starts at the fracture site and advances out.
How much of the IM cavity can a pin take up when using both IM pin and plate?
35-40% if using a combined plate/rod.
What type of stress is created during axial loading or bending in a locking plate construct?
Shear stress is converted to compressive stress at the screw/bone interface
This conversion helps in load distribution across screws.
What is the weakest part of the plate/screw/bone construct?
The shear strength of the interface between bone and screw
This interface is critical for the stability of the construct.
List the advantages of locking plates
- Does not need to be perfectly contoured to the bone
- Easier to apply in a minimally invasive manner
- More difficult for locking screws to pull out
- Prevents overtightening of the bone to the plate
- Fail at higher loads compared to conventional plating
- Larger diameter screws increase resistance to bending
These advantages contribute to better outcomes in fracture healing.
What is a disadvantage of locking plates?
The screw/plate interface may be subject to fatigue at greater rates than the plate or screws alone
This can lead to potential failure if not managed properly.
What forces affect a butterfly fracture?
- Compression
- Bending
- Torsion
- Shear
- Tension
Understanding these forces is crucial for effective treatment.
What is interfragmentary strain?
The amount of movement within the fracture space: change in length / original length
This measurement is important for assessing fracture stability.
What does open anatomic reconstruction aim to achieve?
To completely remove the fracture gap or minimize it as much as possible
This is particularly important for minimally comminuted fractures.
What is the goal of biological osteosynthesis?
To stabilize the proximal and distal fragments in a bridging fashion
This allows granulation tissue to form and reduces strain.
What are three appropriate internal fixations for a femur fracture?
- Bridging plate
- Rod and locking bridge plate
- Interlocking nails
- Lag screw + neutralization
Each option serves different scenarios based on fracture type.
What are two general causes of delayed fracture healing?
- Instability
- Lack of blood supply
Both factors can significantly affect the healing process.
What is the function of a bridging plate?
Takes all the load until callus has healed, providing no load sharing for comminuted non-resectable fractures
This design is crucial for managing complex fractures.
How do neutralization plates work?
They neutralize the forces that the bone fragments are experiencing, providing load sharing
This is particularly useful for simple long oblique fractures.
What is an advantage of locking compression plates compared to dynamic compression plates?
LCPs do not rely on the bone/plate interface for stabilization and provide a stiffer construct
This results in less biological damage and increased rigidity.
What type of bone healing results from LCP placed in compression mode?
Direct or primary bone healing
What is the result of closed reduction and application of Linear ESF?
Indirect bone healing via a small fracture gap
In small dogs, what anatomical and physiological factors affect healing and fixation options for distal antebrachial fractures?
Susceptibility to fractures, reduced vascular density, small cross-sectional diameter
How does the vascular density in small and toy breed dogs compare to large breed dogs?
Reduced vascular density in the distal radial diaphyseal/metaphyseal junction
What is the consequence of reduced vascular density in small and toy breed dogs?
Delayed healing responses
What is a logistical challenge for surgeons when dealing with small and toy breed fractures?
Realigning the bones correctly due to small cross-sectional diameter
What precautions should be taken when drilling in small dog fractures?
Use low speeds to prevent heating due to limited soft tissue
What percentage of distal radial fractures treated with casts resulted in malunion or non-union?
83%
What is important for the healing of distal radial fractures?
Rigid stabilization and optimizing apposition while preserving blood supply
What are some adequate options for treating distal radial fractures?
- ESF with acrylic connecting bars
- Open reduction and bone plating
What is the chance of healing with open reduction and bone plating?
70-85%
What is the risk of complications with open reduction and bone plating?
50%
How long is extra bandaging or splinting used for additional support?
3-4 weeks
What imaging technique is used to monitor for developing osteopenia?
X-rays
What signs indicate the need for staged destabilization in fracture treatment?
Thinning cortices or reduced opacity of bone
What is the process for staged destabilization?
Remove screws closest to the fracture, working outwards, checking/repeating every 3-4 weeks
