SASx Exam I Material Flashcards
1
Q
What determines the bending strength of a screw?
A
Core diameter
2
Q
T/F: Animals with partial-thickness burns involving less than 15% TBSA require minimal supportive therapy, whereas those with burns involving more than 15% TBSA require emergency supportive care
A
True
3
Q
T/F: For the best lag screw function, partially-threaded cancellous screws should be used
A
False
cortical screws are best
4
Q
T/F: Surgical drains should never be placed directly under the suture line
A
True
This would increase risk of dehiscence
5
Q
In the case of quadriceps contracture, muscle fibers are replaced by __________
A
fibrous tissue
Muscle fibers are replaced by fibrous tissue; adhesions form between muscle and bone. Changes result in severe decrease in limb mobility. Periarticular fibrosis/joint ankylosis/DJD further inhibits limb function. This is often irreversible
6
Q
If a dog presents with burns covering both of his hind limbs and his tail, approximately what percentage of his total body surface area (TBSA) is burned?
A
~37%
- Each hind limb is ~18% TBSA. The tail is ~1%.*
- 18 + 18 + 1 = 37*
7
Q
What type of flap is pictured below?
A
Single Pedicle Advancement Flap
- Donor skin available on only one side
- Subdermal plexus flap
- Used when simple undermining and advancement would result in excessive tension or distortion of surrounding tissue
8
Q
What type of fixator is shown in the image?
A
Type I a
9
Q
What percentage of the intramedullary canal should be filled when an intramedullary (IM) pin is used with cerclage wire?
A
70%
10
Q
You see a dog on emergency with a laceration as a result of a dog fight. You debride and lavage the wound but are not sure it is appropriate for closure so you decide to leave it open for additional observation and lavage. Two days later you decide it is ready for closure. What type of closure is this?
A
Delayed primary closure
11
Q
T/F: Hybrid fixators are useful for treatment of metaphyseal fractures
A
True
12
Q
How far apart from the fracture ends should cerclage wires be placed?
A
0.5 cm
13
Q
T/F: Tightening a position screw pulls the trans cortex closer to the cis cortex causing compressions across the fracture
A
False
Tightening a _lag screw_ pulls the trans cortex closer to the cis cortex causing compressions across the fracture
_Position screws_ are placed across a fracture line to hold a fragments in place; No compression across the fracture is achieved
14
Q
T/F: Split-thickness graft is the most common type of skin grafting technique
A
No.
Full-thickness graft is the most common grafting technique
15
Q
What is the best method for intraoperatively detecting radiolucent foreign bodies?
A
Ultrasound
16
Q
The ratio of volume of open space to volume of total bone is termed:
A
Porosity
17
Q
When placing cerclage wires, they should be placed ~0.5 cm from the fracture ends. How far apart from each other should they be placed?
A
~0.5 - 1.0x bone diameter
18
Q
T/F: Drains should always exit through the primary incision to prevent excessive maceration to tissues
A
False
Drains should never exit thru the incision line! This may inhibit proper wound healing
19
Q
When a wound is closed within 1 to 3 days after injury, when they are free of infection but before granulation tissue has appeared, this is known as:
A
delayed primary wound closure
20
Q
T/F: When using external skeletal fixation, fractures will heal by primary bone healing
A
False.
When using external skeletal fixation, fractures will heal by secondary bone healing
21
Q
What are the risk factors associated with quadriceps contracture?
A
- Distal femoral fractures
- Young patients (< 6 months)
- Prolonged immobilization
- Extensive muscle/ST trauma
22
Q
What type of closure is shown here?
A
secondary closure
wound closure after granulation tissue covers the wound
23
Q
T/F: You should never use orthopedic wire as a sole method of fracture fixation, with the exception of some mandibular fractures
A
True
24
Q
With what bone plate application does the implant bear all of the weight load at the level of the fracture?
A
Bridging plate application
- No load sharing at level of fracture due to lack of anatomic reconstruction
- Screw holes left empty at level of fracture
- Micro-motion at fracture site promotes secondary bone healing
25
T/F: Intramedullary pins have good resistance to bending forces, but poor resistance to axial and rotational forces
**True**
26
When placing transfixation pins, pins should be placed ____ away from the fracture and each other
When placing transfixation pins, pins should be placed **_1/2 bone diameter_** away from the fracture and each other
27
What types of fractures are suited for repair/stabilization via **cross pinning**?
**simple, transverse fractures close to the joint**
* *Usually young animals, Salter Harris I and II*
* *Fragments must have good contact to provide load sharing*
28
What type of screw is best for use in metaphyseal and epiphyseal bone?
**Cancellous Screws**
* *Best for use in metaphyseal and epiphyseal bone (trabecular bone)*
* *Increased outer diameter to core diameter ratio*
* *Deeper thread*
* *Larger pitch*
29
Name the cerclage wiring technique used on short oblique fractures in conjunction with a K-wire:
**Skewer pin**
30
Screw diameter should not exceed \_\_\_\_% of bone diameter when used in diaphyseal bone
**40%**
*Screw diameter should not exceed 40% of bone diameter when used in diaphyseal bone*
31
Cortical bone has a porosity of ~\_\_\_\_\_\_%
**5-10%**
32
What is the term used for the dotted line in the image below?
**bridging incision**
## Footnote
*Incision (red arrow) that connects base of flap and recipient site – avoids having to tube flap over intact skin*
33
What is the most common complication associated with external skeletal fixation?
**Pin tract morbidity/drainage/infection**
34
Povidone iodine’s duration of activity in a wound is approximately:
**4-6 hours**
35
What are the general indications for **external coaptation**?
**fractures below the knee and the elbow**
* *Minimally displaced fractures and those amenable to reduction*
* *Transverse, simple, closed fractures*
* *Greenstick fractures*
* *Non-articular fractures*
36
What are the two types of **non-union** fracture healing complications?
**viable and non-viable**
* **Viable**: Biologically active fracture with cartilage and fibrous tissue between fracture ends
* **Nonviable**: Fracture ends are sclerotic with rounded bone edges and visible fracture gap
37
A wound is left open for 2-5 days and closed prior to visible formation of granulation tissue. How would you classify this wound closure?
**Delayed primary closure**
38
What are the "Four A’s" of radiographic evaluation when reviewing post-op or recheck radiographs of a fracture repair?
**Apposition, Alignment, Apparatus, Activity**
* *Apposition*
* *Are fracture fragments well apposed?*
* *Not important w/ biologic osteosynthesis*
* *Alignment*
* *Are the joints above and below the fracture aligned to promote normal limb use?*
* *Include joints in all x-rays*
* *Apparatus*
* *Is the fixator/implants appropriately positioned?*
* *Screw/pin length and positioning*
* *No penetration of joint surfaces*
* *Is there evidence of implant loosening or failure?*
* *Activity. Is there evidence of:*
* *Bone healing; infection; osteopenia; malunion*
39
What is the most common source of surgical wound contamination?
**patient's endogenous flora**
40
When placing a transfixation pin, the pin diameter should be no more than \_\_\_% of the bone diameter
**25%**
*When placing a transfixation pin, the pin diameter should be no more than **_25%_** of the bone diameter*
41
What are the **two approaches** to internal fixation?
1. **open anatomic reduction/reconstruction**
2. **biological osteosynthesis**
42
What type of bone plate would be appropriate for fractures of curved bones (mandible, ileum, etc.)?
**reconstruction plate**
43
What wound dressings would you use to promote granulation tissue formation?
**calcium alginate, honey, sugar, maltodextrin**
44
Name the forces that are overcome by **external coaptation**:
bending & rotation (to a degree)
45
When using conventional bone plates, stable repair requires screw purchase of at least ____ cortices above and below fracture
**Six**
*When using conventional bone plates, stable repair requires screw purchase of at least _6 cortices_ above and below fracture*
46
What does the acronym **MIPO** stand for?
**Minimally Invasive Plate Osteosynthesis**
47
How would you classify this open fracture?
**Type II**
* *Open wound \> 1 cm in size
*
* *Wound from external source*
* *Mild soft tissue trauma-Without extensive soft tissue damage*
* *No flaps or avulsions
*
48
Debridement that begins at the top layer and works toward the deepest describes:
**layered debridement**
49
How soon before surgery are **pre-sutures** usually placed?
**\<24 hours**
*Usually placed the day before surgery. Pre-suturing takes advantage of the properties of mechanical creep and stress relaxation*
50
Salter-Harris Type ____ fractures run through the physis and the epiphysis and are generally articular fractures
**_Salter-Harris Type III_** fractures run through the physis and the epiphysis and are generally articular fractures
51
\_\_\_\_\_\_\_\_\_\_ fractures have multiple fracture lines
**comminuted**
*Comminuted fractures have multiple fracture lines*
52
A __________ fracture, occurring in immature animals, is an incomplete fracture in which a portion of the cortex is intact, thus stabilizing the bone to some extent
**greenstick**
*A greenstick fracture, occurring in immature animals, is an incomplete fracture in which a portion of the cortex is intact, thus stabilizing the bone to some extent*
53
Identify the type of external skeletal fixator:
**Type Ia**
*unilateral-uniplanar*
54
What two types of Salter Harris fractures might go undiagnosed on initial radiographs?
**Type I and Type V**
55
Cancellous bone has a porosity of ~\_\_\_\_\_%
**75-95%**
56
What bone plate mode is used in biological osteosynthesis/MIPO?
**bridging mode**
* *Plate spans fractured area which cannot be anatomically reconstructed (comminuted area)*
* *Plate must “bridge” fracture gap*
* ***_Plate bears all load at level of fracture_***
* *No load sharing at level of fracture due to lack of anatomic reconstruction*
* *Screw holes left empty at level of fracture*
* *Micro-motion at fracture site promotes secondary bone healing*
* *Longer plate with fewer screws*
57
In biomechanics, what is the term for the point at which a material transitions from elastic to plastic deformation?
**Yield Point**
58
When a wound is closed immediately, this is known as:
**primary closure**
59
What **bone plate** type is illustrated below?
**dynamic compression plate (DCP)**
60
Wound closure after granulation tissue formation is considered what type of closure?
**Secondary closure**
61
What antibiotic is the best first choice for treatment of an open fracture?
**Cefazolin**
62
If a dog presents with burns covering his left front limb and his right hind limb, approximately what percentage of his total body surface area (TBSA) is burned?
**~27%**
* Front limb is ~9% TBSA. Back leg is ~18%*
* 9 + 18 = 27*
63
Which of the following three types of screws is the strongest under bending stress:
## Footnote
**cancellous, cortical, locking**
**locking screw**
*The locking screw is strongest under bending stress b/c it has the largest core diameter; it’s only placed perpendicularly to the plate hole*
64
What are the four primary bone tumors diagnosed in our small animal population?
**osteosarcoma, chondrosarcoma, fibrosarcoma, hemangiosarcoma**
65
Salter-Harris Type ____ fractures run through the physis and a portion of the metaphysis
**_Salter-Harris Type II_** fractures run through the physis and a portion of the metaphysis
66
To reduce a fracture, implants are placed through incisions distant to the fracture itself.
This describes *what approach* to fracture reduction?
**minimally invasive osteosynthesis**
* *Implants are placed through incisions distant to the fracture*
* *Fracture is not approached*
* *Closed reduction*
* *I**ntra-operative fluoroscopy is used to guide placement of implants and to confirm fracture reduction and alignment*
* *Steep learning curve*
*\*\*is thought to promote faster bone healing\*\**
67
T/F: Mechanically, a properly applied cast immobilizes the joints above and below the fractured bone, neutralizing bending, rotational, and axial forces on the fracture
**False**
* Mechanically, a properly applied cast immobilizes the joints above and below the fractured bone, _neutralizing bending and rotational forces_ on the fracture.*
* A cast _does not counteract axial forces_ applied to the fractured bone*
68
What technique is used to stabilize Salter Harris Type 1 fractures of the proximal humerus?
**Diverging Pin Technique**
69
How would you classify an open fracture with bone exposure and extensive soft tissue loss?
**Type III B**
70
\_\_\_\_\_\_\_\_\_\_ fractures occur when the insertion point of a tendon or ligament is fractured and distracted from the rest of the bone
**avulsion**
*Avulsion fractures occur when the insertion point of a tendon or ligament is fractured and distracted from the rest of the bone*
71
What type of screw has the **largest core diameter**?
**locking screws**
* *Screw type with largest core diameter*
* *3.5 mm locking screw = 2.9 mm core diameter*
* *3.5 mm cortical screw = 2.4mm core diameter*
* *Self-tapping*
* *Threaded head locks into threaded hole in locking plate*
* *Can only be placed perpendicular through hole*
* *Only for use with locking plates*
72
Briefly describe the "open but do not touch" approach to fracture reduction:
* Fracture is surgically approached and visualized
* _Fracture ends are NOT manipulated during placement of implants_
* Fracture reduced via traction or manipulation of bone away from fracture
* Minimal disturbance of fracture hematoma, periosteum, and blood supply
73
What type of bone plate is most often used for **minimally invasive plate osteosynthesis (MIPO)**?
**locking plate (LCP)**
74
What percentage of the intramedullary canal should be filled when an intramedullary (IM) pin is used along with plating?
**35-40%**
75
When using **locking bone plates**, stable repair requires screw purchase of at least ____ cortices above and below fracture
**Four**
When using **locking bone plates**, stable repair requires screw purchase of at least _4 cortices_ above and below fracture
76
What fracture configuration is ideal for the use of cerclage wire?
**Long Oblique**
*Fracture line should be greater than 2x the diameter of the bone*
77
**Dynamization** is typically recommended at ~\_\_\_\_\_ post-repair
Dynamization is typically recommended at **_~6 weeks post-repair_**
## Footnote
*Dynamization is the Incremental destabilization of the construct. This allows increased axial loading of the fracture to enhance callus hypertrophy and remodeling of the fracture*
78
Identify the type of external skeletal fixator:
**Type IIb**
*bilateral-uniplanar; use of full pins and half pins*
79
What is the difference between anatomic and physiologic degloving injuries?
* **Physiologic**: skin devitalized but still in place
* **Anatomic**: skin avulsed from underlying tissue
80
"bone remodels based on the forces that are applied" describes *what theory*?
**Wolff's Law**
81
What fixation methods (2) cannot be used in the radius?
**Interlocking nails and Intramedullary pins**
82
T/F: **Tension bands** are appropriate for many long oblique fractures
**No.**
*Tension bands are indicated for avulsion fractures and some osteotomies*
83
surgical immobilization of a joint by fusion of the adjacent bones is termed:
**arthrodesis**
84
T/F: **Punch grafts** are used to enhance epithelization
**True**
85
T/F: Lag screws should be positioned parallel to the fracture line
**False**
*Lag screws should be positioned PERPENDICULAR to the fracture line*
86
When is the **diverging pin technique** used?
**to stabilize Salter Harris 1 fractures of the proximal humerus and the femoral head**
87
**Elastic Plate Osteosynthesis** is only appropriate for what type of patient?
**skeletally immature animals**
*less than 5-6 months of age is ideal*
88
T/F: There is less risk of infection with active drains compared to passive drains
**True**
89
The most common bone plates are composed of stainless steel and are very stiff. How do these plates fail?
**bending forces**
90
Classify this open fracture
**Type I**
*A type I open fracture is caused by the bone penetrating through the skin and is characterized by a small puncture hole located in the skin in the proximity of the fracture. Depending upon the amount of soft-tissue coverage, the bone may or may not be visible in the wound.*
91
What type of fixation would be best for treatment of a Grade IIIA open fracture?
**External Skeletal Fixation**
92
What fractures must *always* be anatomically reconstructed?
**Articular fractures**
93
T/F: **Interlocking nails** are used to treat diaphyseal comminuted fractures
**TRUE**
94
This plate is being used in __________ mode
**buttress**
* *Used in a metaphyseal fractures to prevent collapse of the adjacent articular surface*
* *Will frequently incorporate lag screws*
* *Plate is subject to full loading*
* *Axial forces do not help with fracture compression and do not promote load sharing by the bone)*
* *Plate supports cortex and resists displacement*
* *Most or all screw holes should be filled*
95
Name the condition that can occur when a young animal’s comminuted femoral fracture is treated with rigid immobilization for an extended period of time
**Quadriceps contracture**
96
What types of fractures are best repaired by **tension band**?
**avulsion fractures** and **some osteotomies**
97
What is the general goal of **Minimally Invasive Plate Osteosynthesis (MIPO)**?
**To return limb alignment and length to normal without disruption of fracture**
98
What are some indications for **circular fixator** devices?
* Complicated fractures of the tibia and radius
* Distraction Osteogenesis
* Bone lengthening procedures
* Correction of angular limb deformities
99
\_\_\_\_\_\_\_\_\_\_ are small, parallel, staggered incisions made in skin adjacent to a wound to allow closure with reduced tension
**Multiple punctate relaxing incisions**
100
What is the most common organism associated with **bite wounds** in small animals?
***Pasteurella multocida***
101
Identify the fracture:
**lateral humeral condylar fracture**
102
What is the main difference between a **dynamic compression plate (DCP)** and a **limited contact DCP (LC-DCP)**?
**LC-DCP has a contoured underside**
## Footnote
* Allows stress to be more evenly distributed across plate (less stress at screw hole)*
* Less contact with bone = **less disruption of periosteal vascularity**, which reduces the porotic changes under the plate*
103
Which of the following materials is most likely to result in chronically draining non-healing wound?
* Glass shard from a Stag bottle on the strip
* Steel pellets found in a Stag bottle on the strip
* Grass awns found around a Stag bottle on the strip
* Lead bullet fragments
**grass awns**
104
Salter-Harris type ____ classification has been used to describe the partial physeal closures resulting from damage to a portion of the physis and causing asymmetric physeal closure
**_Salter-Harris type VI_** classification has been used to describe the partial physeal closures resulting from damage to a portion of the physis and causing asymmetric physeal closure
105
Because the screws are fixed within the hole of the plate, frictional forces between the plate and bone are unnecessary with *_what type of bone plate_*?
**locking compression plate (LCP)**
* Locking plates and screw systems provide fragment stability with the locking mechanism between the screw and the plate. In a locking plate, because the screws are fixed within the hole of the plate, frictional forces between the plate and bone are unnecessary.*
* The principal method of load transfer is directly through the plate and screw, and termed “screw-only” mode force transfer.*
* \*\*little to no contouring is required with LCP\*\**
106
What types of fractures are best repaired by **interfragmentary wire**?
**Simple fractures of flat, non-weight bearing bones that interdigitate well**
*Most commonly used for certain mandibular and maxillary fractures*
107
T/F: Bone plates should be applied to the tension side of bone
**True!**
108
What is the term used to describe a reversible change in shape in which material returns to its original shape when load is removed?
**Elastic deformation**
109
For what patient populations are acrylic frames best suited?
**toy breed dogs, cats, and exotics**
110
Salter-Harris type ____ fractures are crushing injuries of the physis that are not visible radiographically but that become evident several weeks later when physeal function ceases
**_Salter-Harris type V_** fractures are crushing injuries of the physis that are not visible radiographically but that become evident several weeks later when physeal function ceases
111
Name the forces that are overcome by **interlocking nails**:
**all forces**
*biatch!*
112
Plates that are used in addition to primarily placed lag or positional screws are in __________ mode
**neutralization**
*Plate acts to protect/neutralize against shearing, bending, and rotational forces which would otherwise damage the interfragmentary repair achieved by the screws*
113
T/F: When performing surgery on a clean wound, risk of infection generally doubles every 3 hours
**False**
*When performing surgery on a clean wound, risk of infection generally doubles _every hour_*
114
Identify the type of external skeletal fixator:
**Type Ib**
* *unilateral-biplanar*
* *Pins 60-90 degrees from each other*
* *Interconnecting bars increases rigidity (more stable than IA)*
* *Only types IA and IB can be used on humerus and femur*
115
What type of pinning is illustrated below?
**Retrograde pinning**
116
What bone tumor locations are amenable to treatment by limb sparing?
**Distal radial lesions have best outcome**
*High complication rates though*
117
Name the forces that are overcome by **plating**:
**loading, bending, torsion**
118
What type of screw is shown in the image below?
**self-tapping screw**
You can tell because of the fluted tip. This screw does not require tapping (pre-cutting the thread pattern into the bone following drilling)
119
What type of screw is best for use in dense, cortical bone?
**cortical screws**
* Best for use in dense, cortical bone
* Decreased outer diameter to core diameter
* More shallow thread
* Decreased pitch
120
When placing transfixation pins, you should place at least ___ pins in each bone segment
**Two**
*When placing transfixation pins, you should place at least _2 pins_ in each bone segment. _3 pins per segment_ is ideal for optimal stabilization*
121
An incomplete fracture in which a portion of the cortex is intact, thus stabilizing the bone to some extent, is termed:
**Incomplete (Greenstick) fracture**
122
What osteosarcoma treatment option is associated with the longest median survival time?
**Amputation + chemotherapy**
*Together mean survival time is ~9-12 months*
123
Dirty jokes aside, what is the main indication for "**tubing the flap**"?
"Tubing the flap" avoids making bridge incision but will require a second surgery to cut the flap free after it has healed in the wound bed – usually 14-21 days
124
What are some complications associated with **external skeletal fixation**?
* Pintract drainage: possible infection of soft tissues
* Loosening of pins/wires
* Pin bone interface sustains high stress loads, resulting in bone resoprtion
* Loose pins/wires must be removed
* Osteomyelitis
* Ring sequestrum
* Nerve or vascular damage
125
How would you classify an open fracture in which the wound is smaller than 1 cm, with mild to moderate soft tissue contusion?
**Type I**
126
Why are hybrid fixators particularly useful for treatment of fractures that are close to articular surfaces?
**thin wires or a circular fixator allow for multiple sites of bone purchase in a smaller bone fragment**
*hybrid fixators utilize components of linear and circular ESFs*
127
What tumor types are specific to the digits in the dog?
**SCC and melanoma**
128
inflammation within a joint is termed:
**arthritis**
129
What fixation technique would be ideal for treatment of an avulsion fracture?
**Tension band**
130
\_\_\_\_\_\_\_\_\_\_ is considered to be the single most important element for prevention/treatment of osteoarthritis
**weight management**
131
**Open anatomic reduction** is most appropriate for repair of *what type of fractures*:
**transverse, oblique, segmental, and minimally comminuted fractures**
*\*\*open anatomic reduction is required for articular fractures\*\**
132
Name the **primary implants** that were discussed in lecture:
**bone plates, interlocking nails, external skeletal fixators (ESFs)**
133
Of the four A’s that are evaluated in post-op fracture repair radiographs, which term relates to the positioning of the joints?
**Alignment**
134
T/F: **Axial pattern** flaps are considered transpositional flaps
**True**
135
When placing cerclage wires, how should they be positioned in reference to the long axis of the bone?
**Perpendicular**
136
T/F: Fractures classified as Salter I and II have an articular component
**False**
137
A fracture line perpendicular to the long axis of the bone is a __________ fracture
**transverse**
## Footnote
*A fracture line perpendicular to the long axis of the bone is a transverse fracture*
138
Other than obvious implant migration, what is a radiographic change that would be indicative of implant loosening?
**lucency around the pin**
139
What is the term used to describe a permanent change in shape in which material DOES NOT return to its original shape when load is removed
**Plastic deformation**
140
spontaneous fusion of joint; end stage of joint disease is termed:
**ankylosis**
141
T/F: **Osteochondrosis** is a defect in endochondral ossification
**True**
142
This posture is characteristic for:
**Infraspinatus Contracture**
* *Elbow adducted, antebrachium abducted*
* *Scapulohumeral joint can’t be internally rotated-scapula elevates when shoulder is rotated*
* *Limited range of motion*
* *Usually no pain on manipulation of joint*
143
Muscle shortening not caused by active contraction is termed:
**contracture**
144
What is the most common direction of traumatic shoulder luxation?
**medial**
145
What form of coaptation should be applied for medial shoulder luxation?
**Velpeau Sling**
146
What form of coaptation should be applied for lateral, cranial, and caudal shoulder luxation?
**Spica Splint**
147
This procedure uses heat to shrink and tighten the shoulder capsule:
**capsulorrhaphy**
148
A dog presents with acute onset of pain on palpation of the shoulder. You note malpositioning of greater tubercle. What is your diagnosis?
**traumatic shoulder luxation**
