2 MSK Fractures Flashcards
1
Q
What are the physical forces that must be overcome to allow bones to heal? (5)
A
- Tensile force
- Axial compression
- Shear forces
- Bending
- Twisting/Torsion
These forces must be addressed in the healing process to ensure proper bone union.
2
Q
What type of healing occurs in a DCP in compression mode for a closed mid diaphyseal transverse femoral fracture?
A
Direct bone healing
This involves anatomic reconstruction and may include gap healing occurring simultaneously.
3
Q
What mnemonic can be used to remember the Salter-Harris fracture types?
A
SALTR
Straight across
Above
lower
Through/two
cRush
Each letter corresponds to a different fracture type.
4
Q
What characterizes Salter-Harris Type I fractures? (5)
A
- Straight across
- 5-7%
- Fracture plane passes through the growth plate, not involving bone
- Cannot occur if the growth plate is fused
- Good prognosis
This type is the least severe and has a high chance of healing well.
5
Q
What characterizes Salter-Harris Type II fractures?
A
- Above
- ~75% (most common)
- Fracture passes across most of the growth plate and up through the metaphysis
- Good prognosis
This type is often seen in pediatric fractures.
6
Q
What characterizes Salter-Harris Type III fractures?
A
- Low/Below
- 7-10%
- Fracture plane passes along the growth plate and down through the epiphysis
- Poorer prognosis due to interruption of proliferative and reserve zones
This type can lead to long-term growth issues.
7
Q
What characterizes Salter-Harris Type IV fractures?
A
- Through or Together
- Intra-articular
- 10%
- Fracture plane passes through the metaphysis, growth plate, and down through the epiphysis
- Poor prognosis due to interruption of proliferative and reserve zones
These fractures are more complex and often require surgical intervention.
8
Q
What characterizes Salter-Harris Type V fractures?
A
- Ruined or Rammed, or cRushed
- Uncommon <1%
- Crushing type injury that does not displace the growth plate but damages it by direct compression
- Worst prognosis
These fractures can severely impact growth and development.
9
Q
What are prognostic indicators for Salter-Harris fractures? (5)
A
- Whether growth plate is damaged
- Which bone is involved (e.g., tibia vs ulna)
- Mechanism of injury
- Timing and accuracy of reduction/fixation
- Age at which fracture occurs- how much more growth potential there is
Understanding these indicators can help predict long-term outcomes.
10
Q
In which microanatomic zone does most fractures occur at the physis?
A
Hypertrophic zone
This zone is structurally the weakest part of the growth plate because it has very little matrix, decreased type 2 collagen, increased type X.
11
Q
What are the 4 microanatomic zones of the physis - from metaphysis to epiphysis
A
- provisional zone of calcification
- zone of maturation/hypertrophy
- Proliferative zone
- Reserve zone
12
Q
What are the cellular responses during distraction osteosynthesis? (4)
and what process does it mimic?
A
Bone becomes metabolically activated under traction, leading to:
1. Increased angiogenesis
2. Formation of a hematoma
3. Formation of a procallus
4. Production of new bone trabeculae without a cartilaginous step
This process mimics intramembranous ossification.
13
Q
What are two clinical examples where distraction osteosynthesis is used?
A
- Correcting congenital angular limb deformities
- Correcting limb length secondary to premature growth plate closure issues (after traumatic injury)
- limb sparing surgeries
These conditions often arise in breeds with specific conformation issues.
14
Q
What 2 main factors contribute to fracture non-union?
A
- Lack of adequate stability (mechanical)
- lack of blood supply (biological)
Understanding these factors is crucial for effective treatment.
15
Q
What are the types of viable fracture non-unions? (3)
A
- Hypertrophic (Elephant’s foot)
- Moderately Hypertrophic (Horse’s hoof)
- Oligotrophic
Each type has distinct characteristics visible on radiographs.
16
Q
Radiographic signs of a Fracture non union (3)
A
- Visible fracture gap
- clearly defined fracture ends
- (possibly) a callus that doesnt bridge the gap
17
Q
Biological factors that impact blood supply and bone healing (4)
A
- soft tissue envelope: location of fracture, breed/size
- degree of trauma to soft tissue envelope
- older vs. younger animals:
- Infection
older animals have impaired callous bridging and increased resorbtion through osteoclast activity, decreased osteoblast responses, delayed chondroblast differentiation.
Infection retards healing through inflammation, apoptosis of osteoblasts and increased osteoclast activity.
18
Q
What are the properties of bone grafts for treating non-union fracture repairs? (4)
A
- Osteoinduction
- Osteogenesis
- Osteoconduction
- Osteopromotion
These properties enhance the healing process and promote new bone formation.
19
Q
how does infection affect bone healing?
A
Infection retards healing through inflammation, apoptosis of osteoblasts and increased osteoclast activity.
20
Q
What are the three sites for harvesting autogenous cancellous bone grafts?
A
- Proximal humerus
- Dorsal wing of ilium
- Proximal tibia
These sites provide suitable graft material for bone repair.
21
Q
Mechanical factors that affect bone healing
A
- Choice of fixation: either not enough stability - too much strain
- Too much stability; osteoporosis and resorbtion of bone if implant is taking all the load
Bones remodel depending on the forces they are exposed to (Wolffs law)
22
Q
What characteristierdcs define direct bone healing? (4)
A
- Healing with fractured ends apposed in compression
- no gap, but may involve gap healing (<1mm)
- no strain
- no callus formation
This process involves Haversian remodeling and is efficient when conditions are optimal.
23
Q
What are characteristics of indirect bone healing? (4) and 5 main stages?
A
- small fracture gaps
- variable strain,
- Callus formation
- Endochondral bone healing
involving multiple overlapping stages
1. Inflammatory
2. Intramembranous ossification
3. Soft callus formation
4. Hard callus formation (endochondral ossification)
5. Remodeling
This type of healing is more common and complex.
24
Q
What is Haversian remodelling?
A
One way that bone adapts to its mechanical environment - a repair process in which existing bone is resorbed and replaced by new bone.
Cutting cones composed of osteoclasts and osteoblasts advancing across the fracture plane, cutting a channel into the bone and laying lamellar bone parallel to the long axis of the diaphysis. There is simultaneous resorption and deposition.
25
Tissues that can tolerate:
100% strain
10% strain
2-10% strain
<2% strain
100% strain- Granulation tissue
10% strain - Cartilage
2-10% strain - Woven bone
<2% strain - Lamellar bone
26
Define malunion in the context of fracture healing.
Fully healed fractures where anatomical alignment has not been correctly achieved
## Footnote
This can lead to limb deformities and functional issues.
27
Define delayed non-union in the context of fracture healing.
A fracture that may have formed a callus but is taking longer than expected to heal
## Footnote
This condition can lead to complications if not addressed.
28
What biomechanical factors may contribute to delayed fracture healing? (2)
1. Instability/poor fixation choice/too much strain
1. Large defects (excessive fracture gaps)
## Footnote
These mechanical issues can impede proper healing and require careful consideration during treatment.
If too much strain healing wont progress past cartilage formation.
29
What are the biological factors that may contribute to delayed fracture healing? (3)
1. Poor blood supply: damage, distal limb (poor soft tissue envelope)
1. infection,
1. intrinsic patient factors (older patients, comorbidities ie. diabetes/cushings)
## Footnote
Damage to area affects nutrient and oxygen supply necessary for osteosynthesis
30
What is the resting zone in the microanatomic zones of physis and types of cells it contains?
AKA Reserve zone, Closest to epiphysis, contains hyaline cartilage matrix and small oval chondrocytes
31
Describe the proliferative zone in the physis.
Resting chondrocytes transition to actively mitotic chondrocytes, characterized by stacked coin appearance and less matrix made of Type II collagen
32
What occurs in the hypertrophic zone of the physis?
Chondrocytes hypertrophy and undergo apoptosis. Reduction of Type II collagen, and and increased Type X collagen provides stiffness and prevents nutrient diffusion leading to hypoxia and thus stimulation of vascular angiogenesis.
## Footnote
Structurally the weakest section. Predisposed to Type 2 Salter Harris fractures in young animals.
33
What is the role of the mineralisation/calcification zone in the physis?
Chondrocytes undergo apoptosis and matrix mineralisation occurs, scavenging calcium and phosphorus from adjacent tissues
Further vascular invasion removes calcified cartilage and debris.
34
What happens in the zone of ossification?
Osteoblasts deposit woven bone, following vascular networks, and osteoclasts remodel into lamellar bone over time (Haversian remodelling)
35
What is a Type 1 Salter Harris injury?
Straight across the growth plate
36
What is a Type 2 Salter Harris injury?
Across and above the growth plate line through the metaphysis
37
Why is distal ulnar physeal trauma clinically significant?
The conical distal physis most commonly injured - Responsible for 85-100% of ulnar growth and attached to radius by a ligament in the middle, so damage to physis leads to significant angular limb deformities/elbow incongruity. The radius tends to bow around the ulna, increasing load on radial head and anconeal process.
most common growth plate injury in dogs (63%),
The conical shape is vulnerable to force from any direction, unable to shear regardless of type of force.
38
What is the most common growth plate injury in dogs?
Premature closure of the distal ulna physis due to Type 5 Salter Harris injuries
39
What is osteoinduction?
Transfer of undifferentiated mesenchymal cells into osteoblasts, initiated by TGF-b and Bone morphogenic protein
40
What does osteogenesis refer to?
Formation of new bone by supplying osteoblasts and osteoclasts
41
Define osteoconduction.
Provision of a 3D porous structure that allows adherence and proliferation of cells, and vascular ingrowth
42
What is osteopromotion?
Substances like platelet-rich plasma that enhance proliferation and differentiation of mesenchymal stem cells
43
Where can bone grafts be harvested from? (3)
which is easiest to access?
Proximal humerus, dorsal iliac wing, proximal tibia
## Footnote
Proximal tibia is often preferred for ease of access
44
What are causes of delayed non-unions?
1. Lack of good blood supply,
2. infection,
3. too large fracture gap,
4. lack of stability
## Footnote
Specific examples include damage to blood supply from trauma or fixation method
45
What is the treatment plan for a dystrophic or early atrophic non-union?
1. Remove implants,
2. Debride bone ends,
3. Flush,
4. Take bacterial culture,
5. Graft with autologous cancellous bone
## Footnote
This stimulates the bone healing process and promotes blood supply
46
What type of healing occurs with LCP in compression mode?
Direct healing, where bone ends are placed in compression to remove the fracture gap
47
What type of healing occurs with external skeletal fixation (ESF)?
Endochondral ossification, secondary bone healing process without disturbing the initial hematoma
48
What challenges do toy breeds face in distal antebrachium healing?
1. Poor tissue envelope,
2. decreased vascular density,
3. difficulty establishing bone apposition
4. Difficult to place appropriate sized plates
5. Easy to damage (thermal injury)
## Footnote
These factors complicate healing and increase risk of osteonecrosis
49
What are the risks associated with rigid stabilization in toy breeds?
Osteopenia due to stress reduction, necessitating sequential screw removal
50
what is this type of plate?
DCP
Dynamic Compression Plate
51
type of plate?
LCP plate
Locking compression plate
52
type ?
LC-DCP
Low contact, dynamic compression plate
53
Down side of Direct bone healing?
Slower healing
54
Define Atrophic Non Union
a fracture that has stopped healing and shows no new bone growth. It's a type of aseptic nonunion, which means it's not infected.
55
define Dystrophic non union
a type of nonviable fracture that occurs when blood supply to a bone fragment is impaired. This prevents the fragment from healing properly and can lead to obstruction.
56
Radiographic signs of a dystrophic nonunion: (3)
1) A persistent gap between the fracture ends
3) Rounded, sclerotic fracture ends
3) Lack of callus formation
57
Viable non unions vs. non-Viable non unions
A "viable nonunion" refers to a fractured bone that has not healed but still has a good blood supply and the biological potential to heal on its own, while a "non-viable nonunion" indicates a fracture site with poor blood flow, essentially lacking the ability to heal naturally due to a lack of viable tissue at the fracture site.
A viable nonunion is considered "active" with potential for healing with proper treatment, whereas a non-viable nonunion is "inactive" and requires more aggressive surgical intervention to restore blood supply and facilitate healing.
58
Viable vs. Non viable non- unions:
Blood supply:
Callus formation:
Treatment approach:
Viable nonunion has adequate blood supply, while non-viable nonunion has poor blood flow to the fracture site.
Viable nonunion may show significant callus formation on X-rays (new bone growth attempting to heal the fracture), while non-viable nonunion often lacks visible callus formation.
Viable nonunion may be treated with stabilization procedures to allow the body to heal naturally, while non-viable nonunion usually requires bone grafts or other procedures to reintroduce blood supply to the fracture site.
59
What is the difference between atrophic and oligotrophic nonunion?
Oligotrophic: The bone nonunion is vascularized but there is no callus formation seen on x-rays.
Atrophic: The bone with the nonunion does not have blood flow (avascular) and there is no evidence of callus formation in their x-rays.
60
Describe Hypertrophic non union
hypervascular, viable, vital
non-union is linked with inadequate immobilization and appears to have on adequate blood supply and healing response.
In radiographs, hypertrophic non-union shows increased callus formation with a horse-shoe or elephant-foot configuration, and visible fracture gap
61
how do you grade open fractures?
Type 1: <1cm skin wound, clean, simple fracture
Type 2: skin wound <1cm, no flaps/avulsions, simple fracture
Type 3: extensive soft tissue damage, mulitple fragments, severe crush injury, severe contamination, requires vascular repair.
62
Principles for surgical care of open fractures: they need (6) -
1. prompt diagnosis
2. IV Ab's
3. Meticulous debridement
4. Fracture stabilisation
5. Second debridement may be needed after. 48hrs
6. Early soft tissue bandaging
63
what is an appropriate IV AB for open fracture
Cefazolin q8hrs,
Penicillin
Metronidazole
64
how do you decide whether to remove a bony fragment or not?
If its attached to soft tissue ok to leave
65
Fixation methods for open fractures:
low grade =
high grade =
low grade= what you would use for similar closed injuries: interlocking nails,
Can also delay primary fixation, and use temporary external fixation
high grade/severe = external fixation preferrable
66
how much of intramedullary canal should IM Pins take up?
what if you only have smaller pins?
70-80%
you can use multiple pins at once
67
how often are radiographs taken to assess bone healing?
every 4-6 weeks
68
Benefits of locking plates
They are more tolerant of slight inaccuracies in plate contouring
69
how many screws are needed with bone plates,
3 screws proximal and 3 distal to fracture
70
Disadvantage of IM pinning humeral fracture
Nail migration is possible into supracondylar notch of distal radius- will interfere with extension of limb
71
4 A's of fracture Assessment
1. Alignment
2. Apposition
3. Apparatus
4. Activity
72
Apposition
looking for >50% contact of fractured surfaces
Does it change over time?
- instability?
- infection?
73
Alignment
Joint above and below
Varus/Valgus
Internal or external rotation
Procurvatum/Recurvatum
Translational malalignments
Requires consistent positioning to compare between radiographs
73
Apparatus
Appropriate Size, position, application
Structural integrity: loosening? deformity of bone plate, breakage, missing implant pieces,
74
Activity
looking for evidence of bone healing at the fracture site
primary vs. secondary
Can be a combination of both
Is there biological union? (obliteration of all fracture lines/gaps?)
Clinical union = bridging callus of fracture line of 3 of 4 cortices
75
Radiographic signs of healing complications fracture repairs: (5)
- quality of callus
- bone lysis/resorbtion/osteopenia
- Implant loosening/failure
- soft tissue swelling
- angular limb deformity in growing dogs
76
how do you use 4A's in clinical decision of fracture management
Combine assessment with history and physical exam findings
77
Possible complciations that can occur during fracture healing (5)
1. Malunion
2. Implant Failure
3. Delayed union
4. Non union
5. Osteomyelitis
78
how much does soft callus contribute to stability in a fracture
50%
79
The fracture gap appears larger in early stages of fracture healing, true or false?
True: bony resorption occurs after which the callus becomes more visible
80
81
What 5 things do you assess to assess biology of fractures?
1. Age
2. Blood supply
3. Fracture gap
4. Infection
5. Concurrent injuries/disease
82
how quickly would you expect fracture to heal with
1) good biology (young, large soft tissue envelope, low energy fracture)
2) Poor biology (old, poor soft tissue envelope, comminuted)
Good: 8wks
Poor: 16-24wks
83
Biomechanical factors in fracture assessment (3)
1. Number of limbs affected
2. Is it anatomically reconstructable/is load sharing possible?
3. Is there sufficient bone for implants to be attached
## Footnote
combining biological and mechanical factors helps make decision regarding type of fixation method
84
Can you use various types of screws in DCP plates?
Downside of DCPs?
1. no - only cortical screws
2. need good plate contouring to achieve direct contact and load sharing-> causes more soft tissue damage
85
Benefit of LC-DCP
Downsides
1. Scalloped plate- doesnt damage periosteum so much
2. Still need to contour to the bone, still can only use cortical screws
86
Pros/cons LCP's
1. you can use locking screws;
2. Dont need to contour plate
3. plate acts in a bridging fashion- can take all the load
4. can use cortical and locking screws
87
88
when placing screws on locking plate, which screws are placed first - cortical or locking?
cortical - pull the plate close
89
What is the initial step in the history taking process for a dog with lameness?
Determine if there was an initial incident prior to noticing signs or if it gradually increased over time.
90
Lameness: What questions should be asked regarding the dog's exercise in the history taking?
Was it worse with exercise or better?
91
What aspects of the dog's lameness should be clarified during history taking? (6)
How long has it lasted
Constant/intermittent,
getting worse or better,
any treatments provided,
any response.
Any previous injuries
92
What should be assessed during the physical examination of a dog with suspected lameness? (8)
Overall gait,
standing posture,
muscle development,
Muscle symmetry,
Any visible wounds or injuries.
Neurological symptoms
Joint pain with PROM or direct palpation
Directly palpate bones
93
What specific joint assessments should be performed during a physical examination? (4)
Manipulate joints,
assess range of motion,
palpate for pain,
check for effusion.
94
Fill in the blank: Any forelimb lameness in a young dog should always have ______ as soon as possible.
X-rays
95
What are some differential diagnoses for a young dog presenting with forelimb lameness? (7)
* Elbow dysplasia
* Elbow incongruity
* Panosteitis
* Hypertrophic osteodystrophy
* Retained cartilage cores
* Immune mediated arthritis
* Septic arthritis
96
What are the recommended X-ray views for assessing the elbow?
* Flexed lateral
* Standing lateral
* Craniomedial oblique 15 degrees
* CC
97
What are the findings associated with a fragmented medial coronoid process?
Bilateral subchondral bone sclerosis and a displaced fragment on the left.
98
What treatment is recommended following the diagnosis of elbow issues?
Bilateral arthroscopy and debridement as needed.
99
What postoperative recommendations should be given to the owners?
* Keep the dog lean
* Moderate/gentle exercise
* NSAIDs for pain
* Joint diet and supplements
100
What is the prognosis for a dog after surgery for elbow issues?
Arthritis will develop but will be much less with surgery.
101
What are the radiographic findings for a 16-week-old Labrador with a bunny-hopping gait?
Severe bilateral hip dysplasia with limited femoral head coverage.
102
What is a recommended intervention for young dogs with hip dysplasia?
Juvenile pubic symphysiodesis.
103
What should be checked during the physical examination of a dog with bilateral hindlimb lameness?
* Reduced muscle mass
* Prominent greater trochanters
* Swaying hindlimb gait
* Wide based stance
104
What are the radiographic findings for bilateral hip dysplasia?
Both femoral heads are flattened and not fully seated within the acetabular rim.
105
What is the significance of performing an Ortolani test under general anesthesia?
To confirm the diagnosis of hip dysplasia.
106
What are the management strategies for arthritis in dogs?
Manage arthritis by:
* Keeping lean
* Gentle low impact exercise
* Joint diet/supplements (keep on puppy food until grown)
* Cartrophen course
## Footnote
These strategies aim to alleviate symptoms and improve joint health.
107
What is the ideal surgical procedure for managing hip dysplasia in young dogs?
Ideal candidates for a double or triple pelvic osteotomy
## Footnote
This procedure helps manage arthritis but does not stop its development.
108
What are the considerations for performing a total hip replacement (THR)?
Consider THR now or wait until arthritis becomes a quality of life issue
## Footnote
The decision depends on the severity of arthritis and the dog's overall health.
109
What are the risks associated with high morbidity surgeries for hip dysplasia?
High morbidity surgeries have significant complications, including:
* Risk of cutting the sciatic nerve
## Footnote
Surgical decisions should weigh the risks and benefits carefully.
110
What are the radiographic findings in a dog with suspected hip dysplasia?
Radiographic findings may include:
* Bilateral coxofemoral partial luxation
* Thickened femoral necks
* Remodeling of the acetabular rim
* Osteophytic growth around the acetabulum
* CFHO and CCO on femoral heads
## Footnote
These findings indicate joint instability and potential arthritis.
111
What is the recommended management for a dog with hip dysplasia showing arthritic changes?
Advise stopping work and transitioning to a companion dog
* Use usual OA management tools
* Consider THR bilaterally
## Footnote
Early intervention can prevent further complications.
112
What are the key diagnoses for a seven-year-old Maltese with lameness?
Diagnoses include:
* Bilateral hip dysplasia
* Cruciate rupture of the cranial cruciate ligament in the right stifle
* Vertebral spondylosis between L7 and S1
## Footnote
These conditions collectively contribute to the dog's lameness.
113
What is the gold standard surgical procedure for a cruciate rupture?
TPLO (Tibial Plateau Leveling Osteotomy)
## Footnote
This procedure is preferred for stabilizing the stifle joint.
114
What is the post-operative care for a dog undergoing stifle surgery?
Post-operative instructions include:
* Good pain relief (MLK, NSAIDs)
* Strict rest for 2 weeks
* E-collar usage
* Rechecks at one week
* Consider starting Cartrophen after 1 week
* Graduated return to activity
## Footnote
Effective pain management and rest are crucial for recovery.
115
What diagnostic steps should be taken for a dog returning with increased lameness post-surgery?
Diagnostic steps include:
* X-rays to assess implant integrity
* Arthrotomy to check for meniscal tear
* Aseptic arthrocentesis to check for infection
## Footnote
Timely diagnosis is essential to address complications.
116
What findings would indicate infection in joint fluid analysis?
Presence of neutrophils with a ratio greater than 1-2 Neuts/PHF (non spun sample)
Neutrophil: Mononuclear cell > 11:1 = septic
## Footnote
High neutrophil counts suggest an inflammatory or infectious process.
117
What is the recommended treatment plan if joint fluid analysis indicates infection?
Treatment plan includes:
1. Culture joint fluid (blood culture best)
2. Start empirical antibiotics (amoxiclav or cephalexin), pending culture min 28days
3. Joint irrigation with copious amounts of sterile saline using a 3 way tap and egress needle set "flush until you get bored, twice'
4. Abs until joint fluid culture is normal x 2 separate occasions
## Footnote
Thorough flushing and appropriate antibiotics are critical for managing joint infections.
118
Fill in the blank: The ideal time for TPO/DPO surgeries is _______.
20 weeks to 7 months
## Footnote
This timeframe is optimal to prevent arthritis changes.
