SAS - Exam 3 M

proper nutrient artery supplies

• major cavity - 30%

• inner 2/3 of cortical bone -70%

if you have damage to the nutrient artery, what blood vessels hypertrophy

• Proximal / distal, metaphyseal arteries

True or false

epiphysis arteries only supply the epiphysis

• true they do not cross

When you have a fractured, long bone and majority circulation is initially disrupted where does blood supply come from?

• soft tissues in the area

• periosteal circulation (predominates)

• metaphyseal arteries - minor

What are the three stages to fracture healing

• inflammation, repair and remodeling

When a fracture occurs you basal active mediators that increase vascular permeability causing a hematoma formation. Fibrin and platelets bind to collagen that form a clot now known as a organized hematoma.

This clot is a early scaffold for

• migration of reparative cells

• Also see a removal of the vitalized osteocytes and proliferative of extra osseous blood vessels

True or false

During the repair phase on differentiated Makamo cells migrate to injured site where they form a callous, which is the main scaffold

• True

• starts as soft fibrous then hard

Fracture surfaces contact one another what type of healing

• Direct healing

Is a callous formation necessary for direct bone healing

• No

indirect bone healing occurs via

• Endochondral bone formation

Every 4-6 weeks obtain radiographs postoperatively to evaluate what four things

• apparatus

• activity

• alignment

• apposition

If there is evidence of the fracture healing, however not healed within the expected time 10-12 weeks that is known as a

• Delayed union

• to fix you can wait bone graft or stabilize

Explain a non-union fracture

• No radiographic evidence of progression toward healing for three consecutive months

Most common causes of a non-union

• Instability

• poor blood supply

• surgical intervention necessary

What’s the difference between vascular and avascular non-union

• vascular is still viable

What is the main thing that characterizes a vascular non-union

• adequate biologic environment, however, lack of stability

• you will see callus formation of vary degree and radiolucent line at fracture site

What characterized avascular non-union

• Inadequate biological environment

For both vascular and avascular treatment involves removing loose implants, functional alignment, treatment of infection and rigid stabilization

What are two other things you need to do for avascular

• Curettage of fibrous tissue

• cancellous bone grafting

Healed fracture, however anatomic bone alignment not achieved

• malunion

• results in functional problems

Apex of deformity is caudle and distal. limb is directed ____

What is this called?

• cranial

• recurvatum

Apex of deformity is cranial and distal. Limb is directed caudally

• Procurvatum

Wolf law

• Bone will remodel along the lines of stress

Bone graft with the donor and recipient are the same individual

• autograft best option

Bone graft with the donor and recipient are the same species

• allograft

Bone graft with the donor and recipient are different species

• Xenograft

What are the four functions of bone graft (the 4 O’s)

• Osteogenesis

• Osteo induction (promotes progenitor cell migration)

• Osteo conduction (act as a scaffold)

• Osteo promotion (enhances Osteo induction)

four compositions of bone graft

• cortical

• cancellous

• corticocancellous

• synthetic

What part of the bone do you get most of the cancellous bone

• Metaphysis

What composition is a vascular a cellular that provides structural support for large defects

• Cortical allograft

• Provides osteoconduction with minimal osteoinduction

When is cortical allograft contraindicated?

• infection present

Which composition is highly cellular, but mechanically weak

• cancellous autograft

• provides osteogenesis, osteoninduction and osteoconduction

What provides osteoconduction but no osteoinduction

• Cancellous allograft

What is higher cost, loss of living cells, potential decrease in BMPs and a possible compatibility reaction.

Cancellous autograft or cancellous allograft

• Allograft

Indications for a bone graft

• Enhance and promote healing

• bridge defects and establish continuity of bone

• replace cortical segment

• fill cavities

Donor sites for bone graft

• proximal humerus

• wing of ilium

• proximomedial tibia

• distal femur

• proximal lateral femur

True or false

you only harvest your bone graft when you are ready to transfer it

• True

Use separate instruments and gloves for harvesting bone graft and store it in ___

• Blood

True or false

bone graft complications include seeding, fracture, seroma, dehiscence, pain, and morbidity

• True

what fractures are considered urgent?

• open fracture

• fractures communicating with joints

• spinal fracture

thoracic trauma, fracture, head trauma. Rank how you prioritize

• Head trauma

• thoracic trauma (hemo abdomen / uro abdomen )

• fracture

What are the important dermatome you want to assess in your forelimb and hindlimb?

• Radial nerve

• femoral

• sciatic nerve (peroneal / tibial )

Open fracture that is inside out and less than 1cm

• Grade one

Open fracture with mild soft tissue trauma and greater than 1cm wound

• Grade 2

Open fracture with extensive soft tissue injury with bone significantly exposed

• grade 3

What type of dogs usually have a type 4 Salter-Harris fracture of the distal humerus

• Brachycephalic

• What location do you want your implants to be

• tension surface

What are the fracture forces?

• bending - transverse

• bending and axial compression - commuted

• axial compression - oblique

• torsion - spiral

Number one source of infection with sterile surgery

• patient skin

True or false

whenever placing implants in a body, you need to use antibiotics.

• True

• 30 minutes prior to incision then queue 90 minutes

• Cefazolin

Drug of choice for clean, closed fracture and open fracture

• clean closed = cefazolin

• open = broad spectrum (amoxicillin / sulbactam) - continue post operate

After you complete surgery what is important to do

• radiographs to assess alignment, apparatus activity and opposition

• get orthogonal views and compare to previous radiographs

For external co-optation, you use three layers of bandages list them in order

• Non-adherent dressing over a wound

• Cast padding or rolled cotton (bulkiest)

• Gauze then vet wrap

Bandage must incorporate the joint where

• the joint above and the joint below

Bandage must allow for visualization of

• third / fourth digits distally

This bandage provides immobilization compression and protects limb from vascular compromise.

Most common bandage used

• Robert jones

• Additionally, eliminate dead space postop

Robert Jones bandage can only be used on

• Distal, limb injuries

• below stifle below the elbow

What is the goal of the Robert Jones bandage?

• Bulk to give compression and limb immobilization

What type of bandage is used best as an adjunct to support the limb postoperatively.

this bandage gives temporary immobilization and allows for some compression

• Modified Robert Jones

What material do you use for a modified Robert Jones bandage

• Everything except rolled cotton in second layer. You use instead cast padding as your primary layer.

• Note: limb is at a standing angle, because bandage is gonna be there for a long time so more comfortable for the dog when it walks

What is the function of a splint bandage

• Provides temporary immobilization

• Note: does not provide compression

When do you not use a splint bandage

• If there is swelling

Two types of splints and when to use them

• Standard = distal limbs below elbow / step fold

• Spica = proximal limbs. this extends to the opposite hip/shoulder

What do you use if you want to provide a definitive stabilization of a fracture

• Cast (form of indirect bone healing)

What criteria should be met when you are going to consider a cast

• closed fracture

• distal to the elbow and stifle

• mechanically stable and for it to heal quickly

Cast resists bending and rotation forces, but does not counter

• axial forces

After you apply your cast you want to evaluate reduction with radiographs.

you want how much of a reduction of them fracture

• Greater than or equal to 50%

Common complication with casts

• Bandage sores

Purpose of Ehmer sling

• Reduction of a cranial dorsal hip luxation

• works by abducting and internally rotating the hip joint

• removed 10-14 days

Purpose of velpeau sling

• stabilizes shoulder with medial dislocation

• support scapular fracture

• works by prevents weight bearing

Intramedullary pin control what fracture force

• only bending

Intramedullary pens must be used with an adjunct device except for

• physeal fracture in a young dog

If you were using a intramedullary pin as a primary stabilizer it needs to be as big as how much of the medullary canal

• 60-70%

If you were using a intramedullary pin as an adjunct stabilizer, it needs to be as big as how much of the medullary canal

• 30-40%

What bones are appropriate for intermedullary pins?

• humerus, ulna, femur, tibia

• NOT the radius

two insertion methods for intermedullary pins

• Retrograde - inserted at fractured

• Normograde - inserted at proximal end of bone

what are the only bones you can use retrograde

• humerus, ulna, femur

what are the bones you should NOT try normograde

• Ulna

What insertion is recommended in the femur?

• Normal grade

• less risk to sciatic and feces

• inserted into trochanteric fossa

Tibia you can only insert normograde only why?

• Retrograde destroys cranial cruciate ligament or meniscus

• insert medial aspect of crest

Humerus insertion

• can go both normo or retrograde

• proximal lateral to distal medial insertion

ulna insertion

• retrograde

• because canal is very narrow distal

Indications for cross pins

• physeal fractures

• femur/tibia most common

True or false

Cerclarge wire is always used in conjunction with other devices

• true

Indication for cerclarge wire with what type of fracture

• long oblique that is greater than 2x the diameter of bone at fracture site

• Note: fracture must be anatomically reduced and a minimum of two wires used

You apply plates to the tension surface of the bone with how many cortices engaged on both sides of the fracture

• six or more

Three functions of bone plates

• compression - simple transverse fracture

• neutralization - plate protects adjunct fixation

• buttress - plate carries full load

True or false

intramedullary pin with locking bolts controls sheer and rotation and feels 80-90% of medullary canal

• True

You can only use intermedullary pin with locking bolts in what bones

• femur, tibia and humerus

Where do you use tension bands?

• fractures with distractive forces (convert distraction force to a compressive force)

• patella (quads)

• tibial crest (patellar ligament)

• olecranon (tricep)

• do figure 8 with wire

Additionally with long bone fractures what are four other applications you can use with external skeletal fixation

• Arthrodesis

• spinal cord stabilization

• mandibular fractures

• distraction osteogenesis

Component of the ESF system that engages the bone to provide stabilization of fracture repair like a screw would

• pins

Secures the pin to connecting bar

• clamps

connects the clamps to the pins

• connecting bar

What type of ESF is unilateral and uni planar

• type 1A

What is type 1B ESF

• Unilateral but biplanar

type two ESF

• bilateral, uniplanar

type three ESF

• Bilateral, biplanar

ESF system that includes small kishner wires connecting to rings and connecting bars

• circular

applications for a circular ESF

• Severely comminuted fractures

• angular limb deformities

For ESF you want to use threaded pins that use large largest or smallest size allowed by bone geometry

• Largest