Musculoskeletal Flashcards
An orthopaedic exam should always be __ & __
Consistent & Repeatable
List the scale for lameness in dogs and cats
1 - Normal
2 - Mild
3 - Moderate
4 - Severe
5 - Non weight bearing
A head nod to the __ indicates lameness on the forelimb
Good side
I.e., the lameness is opposite to the head nod
List the 3 joints in the carpus
- Antebrachiocarpal
- Middle carpal
- Carpometacarpal
What is the range of motion of the carpus?
Flexion, extension & valgus
Flexion, 150
Extension, 10-20
Valgus, 10-15
Define valgus
Stress applied away from the body
Define varus
Stress applied towards the body
What is the range of motion of the elbow?
Flexion and extension
Flexion, 20
Extension, 150
In which joints is effusion difficult to assess?
The elbow, shoulder
What is the range of motion of the shoulder?
Flexion, extension, abduction
Flexion, 60
Extension, 160
Abduction, 35
What is the range of motion of the hock?
Flexion and extension
Flexion, 20
Extension, 180
What is the range of motion of the stifle?
Flexion, extension and internal rotation
Flexion, 40
Extension, 160-170
Internal rotation, 5
Which tests can you perform to test the integrity of the cranial and caudal cruciate ligaments
The cranial draw test and tibial compression test
What is the range of motion of the hip?
Flexion, extension, and abduction
Flexion, 50
Extension, 160
Abduction, 40
Define arthrocentesis
Removal of fluid from a joint
Describe the method for arthrocentesis of the elbow
Neutral position, palpate the lateral epicondyle and olecranon, and insert the needle parallel to the ulna
Describe the method for arthrocentesis of the antebrachiocarpal joint
Flex maximally, insert needle dorsoventrally medial to the common digital extensor and cephalic vein
Describe the method for arthrocentesis of the stifle joint
Slight flexion, palpate the tibial tuberosity and patella, insert the needle at 45 degrees lateral to the parapatella joint pouch
List 5 properties of synovial fluid
- Clear or pale yellow
- Viscous
- Small volume
- Low cell count
- Mononuclear cytology (NO neutrophils)
List 6 clinical signs of a fracture
- Loss of function
- Swelling
- Change in limb length, alignment or orientation
- Abnormal range of motion
- Pain
- Crepitus
What causes displacement of the fracture ends after a break?
Continued load bearing and muscle contraction
List the 3 requirements for fracture healing
- Stability & reduction of the fracture site
- Absence of infection
- Time
List the 4 goals of fracture management
- Reduce discomfort
- Eliminate ongoing trauma
- Support healing
- Restore function
Describe the steps in callus formation
5 steps
- Haematoma formation
- Granulation tissue
- Vascular invasion & fibroblast differentiation
- Fibrocartilage formation
- Mineralisation
What are 2 general types of bone healing?
- Healing under limited motion
- Primary bone healing
What are the 2 types of primary bone healing?
- Contact healing
- Gap healing
Describe the process of healing under limited motion
When there is some movement at the fracture gap, callus formation causes a progressive increase in the stiffness of the fracture site
What is required for healing by primary bone union?
2 things
Complete stability and no/small fracture gap
Describe the process of contact healing
What will you see on a radiograph if this form of healing happens?
Direct apposition of the fracture ends with NO movement allows remodelling
Reduced radiographic density at the bone ends next to the fracture site
Describe the process of gap healing
Small gaps between the fracture ends with SOME movement allows lamellar bone to form between the fracture gap, and intracortical remodelling restores bone integrity
List
Neutralizing forces causing fractures
- Tension (lengthen)
- Compression (shorten)
- Bending (tension + compression)
- Torsion
- Shear (oblique)
Define a pathological fracture
A fracture secondary to an underlying pathological process that weakens the structure
List 6 categories in which you can classify/assess a fracture
- Aetiology
- Bones involved
- Position within the bone
- Direction of fracture lines
- Number of fracture lines
- Displacement of fracture lines
List 5 classes of fractures based on their position within the bone
- Diaphyseal (the shaft)
- Metaphyseal (end of the shaft)
- Physeal (growth plate)
- Epiphysis (end of the bone)
- Articular (the joint)
What condition will likely develop from an articular fracture
Osteoarthritis
What is an incomplete, greenstick, fracture secondary to in mature animals?
Skeletal demineralisation (nutritional hyperparathyroidism)
What is a fissure?
Cracks coming from the fracture site
List 5 classifications of fractures based on the direction of fracture lines
- Transverse
- Oblique
- Segmental
- Spiral
- Multifragmentary (comminuted)
The displacement of the fracture is always described as the displacement of the __ part
Distal
Define avulsion
When a bone fragement separates from the rest of the bone becasue of a muscle or ligament attachment
Where do avulsions occur in immature animals?
Along the physis
Where do avulsions occur in mature animals?
At the muscular or ligament insertions
Define an impacted fracture
When fracture ends are driven together
How can you recognize fracture healing clinically?
- Improved function
- Consistent weight bearing
- Minimal muscular atrophy
How can you recognize fracture healing radiographically?
- Briding cells
- Loss of fracture lines
Variable signs depending on type of fracture
What are the 3 goals of treating an open fracture?
- Stabilise and manage soft tissue injuries
- Prevent contamination
- Achieve rapid bone union and restore function
Which class of drug should you avoid when treating open fractures?
Corticosteroids
What are the 3 sections of the fracture patient assessment score?
- Clinical
- Mechanical
- Biological
List 3 mechanical factors to consider when scoring a fracture patient
- Type of fracture
- Number of injuries
- Size of the animal
List 5 biological factors to consider when scoring a fracture patient
- Age
- Overall health
- Soft tissue involvement
- Location
- Energy of the fracture
What clinical factor should you consider when scoring a fracture patient?
Patient and client compliance
List the 4 methods of fracture repair
- Conservative
- External
- Internal
- Salvage
Describe biological osteosynthesis as a method of fracture repair
Takes full advantage of biological healing potential to maximise healing, maintains limb length and orientation, and avoids creating further surgical trauma
What is the appropriate emergency method of fracture repair for upper limb fractures?
Cage rest
What is the appropriate emergency method of fracture repair for lower limb fractures?
Robert-Jones dressing & cage rest
For which type of fractures is conservative management (i.e., cage rest) appropriate?
Pelvic fractures & lower limb fractures
List 4
Advantages of external coaptation
- Preserves soft tissue & blood supply (biological)
- Quick
- Few materials
- Generally inexpensive
List 5
Disadvantages of external coaptation
- High maintenance
- Can cause soft tissue injury if done wrong
- Muscle atrophy & joint stiffness
- Osteopenia
- Can only be used below elbow & stifle
Where are splints best used?
The radius and ulna
List 2 materials that can be used to form casts
- Plaster of Paris
- Fibreglass/resin
List 3 advantages for plaster of paris cast material
Cheap, easy to apply and conforms well
List 3 advantages for fibreglass/resin cast material
Light and strong, conforms well, radiolucent
List 3 criteria important for maintaing reduction during cast application
- Immobilising the joint above the fracture
- Immobilising the joint in normal standing position
- Including the toe pads
If healing time is expected to be longer than __, you should avoid using a cast
6 weeks
List 4 biological complications of healing with casts
- Soft tissue injury (pressure sores or ischaemia)
- Fracture disease (muscle wasting or osteoporosis)
- Malunion
- Delayed union
Define external skeletal fixation
A series of percutaneous pins that pass into or directly through the bone
List 3 advantages of ESF
- Versatile
- Easy to apply
- Compatible with the principles of biological osteosynthesis
How is ESF compatiable with the principles of biological osteosynthesis?
It maintains alignment in the limb, minimally disturbs fracture fragments, neutralizes fracture forces and encourages early weight bearing
Define a unilateral ESF frame
Uses half pins
Define a bilateral ESF frame
Uses full pins
What is a type 1 ESF frame design?
Unilateral, uniplanar (straight line running down one side of the bone)
Simplest form
What is a type 2 ESF frame design?
Bilateral, uniplanar (two sides, one plane)
What is a type 3 ESF frame design?
Bilateral, biplanar (forms a triangle shape around the bone)
Most complex
List the 3 different types of fixation pins
- Smooth
- Negative profile thread
- Positive proflie thread
When using which type of fixation pin must you pre-drill a pilot hole?
Positive profile thread pin
How many fixation pins should you place above and below a fracture?
3 above and below
Why would you hang a limb when preparing for ESF frame placement?
It aids in fracture reduction and fatigues the muscles
How wide should your pins be compared to the bone for ESF?
20-25% of the cortical width (1/4)
List 2 complications of using ESF
Persistent pin tract drainage (inevitable in some cases) and loosing pins
What is an Illizarov ESF?
A ring fixator (cESF)
Intermedullary pins for fracture alignment resist bending, but what can still happen?
Rotation, shear, or axial shortening
How can you enhance the stability of an IM pin?
Combine with ESF or plate & screws
How would you select the diameter and length of an IM pin?
You want to fill the medullary canal at the narrowest point and have the pin sitting in the distal metaphysis
Define normograde IM pinning
Introducing the pin away from the fracture site
Define retrograde IM pinning
Introduce the pin at the fracture site
In which bone can you not use IM pinning?
The radius
For which bones can you not use retrograde IM pinning?
The tibia and radius
What is an interlocking nail stabilizer?
An IM pin fitted with bone screws
How is an interlocking nail better than an IM pin?
It neutralizes ALL forces (not just bending), including shortening, rotation and shear
What is an orthopaedic wire?
A monofilament wire 0.8-1.2mm in diameter
When would you use tension band wiring?
To repair fractures or osteotomies which are subjective to distractive forces
Define the features of a self tapping bone screw
They cut their own thread in the bone and have a cutting tip
Define the advantage of using a tapped bone screw
A thread must first be cut into the bone, but the thread on the bone conforms exactly to the screw proflie, so it maximises its holding power
List the steps of bone screw placement
- Drill pilot hole
- Measure depth of hole and add 2mm
- Countersink
- Tap
- Place screw and tigthen
Define a lag screw
When the screw crosses a fracture line that can be compressed
The screw provides compression
Define a position screw
When the screw crosses a fracture line that cannot be compressed
Which part of the bone do screw threads grip to
The far-cortex
So, overdrill in the near cortex to make a gliding hole
Define countersinking
A technique used to create a platform in the near cortex of bone, for when placing a bone screw
Where should you insert a lag screw?
- In the middle of the fragment
- Equidistant from fracture edges
- At 90 degrees to the fracture plane
What is the main advantage of lag screws?
The provide interfragmentary compression
When would you use a position screw?
When a lag screw fragment collapses or when a fragment is too small to make a gliding hole
What are the three ways in which you can apply a bone plate?
- Compression plate
- Neutralisation plate
- Buttress plate
With a compression plate, which side of the plate provides the compression and which side provides the tension
Compression, concave
Tension, convex
For which fractures is a compression plate best suited?
- Transverse fractures
- Short oblique fractures
- Corrective osteotomies
- Articular fractures
How would you place a compression plate?
Why would you do it this way?
In tension (convex to the bone), to apply compression across the fracture gap
When would you use a neutralization plate?
To protect a lag screw reconstruction (plate + screws work together, and the bone takes some weight)
Bc it cannot take significant loads without failure
When would you use a buttress plate?
When a fracture cannot be reconstructed (shattered) and the bone cannot take any weight
Define osteomyelitis
Inflammation/infection of the bone and associated bone marrow
When do we most commonly see osteomyelitis?
As a post surgical infection (70% occur after orthopaedic procedures)
Also after a penetrating injury, as local extension, or spread in blood
Why is osteomyelitis so common at sites where metallic implants are placed?
Because the glycocalys biofilm on the implant shields bacteria in the site from normal host defences
List 3 clinical signs of acute osteomyelitis
- Localised pain
- Swelling
- Pyrexia & anorexia
Usually presents 2-3 days post op
List 5 clinical signs of chronic osteomyelitis
- Lameness
- Bone pain
- Swelling
- Discharging sinus tracts (from Sx)
- Pyrexia & anorexia
What radiographic sign are we looking for to diagnose osteomyelitis?
Bone destruction
List 5 radiographic signs of osteomyleitis
- Bone destruction
- Periosteal new bone formation
- Soft tissue swelling
- Sequestrum formation (solo fragment of dead bone away from normal bone)
- Delayed or non-union
What is most important for a fracture to heal, even with osteomyelitis?
It needs to be stable
Fractures will heal in the presence of persistent infection
Can you treat osteomyelitis with antibacterials?
Yes - culture if possible, and 50-60% of infections involve staph so you can reasonably treat
Treat w prolonged course
What is the difference between delayed union and malunion
Delayed union isn’t a problem bc the bone will heal eventually (but maybe ask yourself why its so slow), but malunion is when the bone doesn’t heal normally because of inadequate fixation or inaccurate reduction
How would you correct a significant deformity from malunion?
An osteotomy and realignment
Define non-union, and the primary cause
When the bone does not heal at all
Usually your fault (poor management, inadequate stability, and excess motion putting high strains on the bone so that it does not progress to mineralisation)
Define a viable non-union, and the two types
A non-union that will heal following adequate stabilisation
There is hypertrophic and oligotrophic viable non-unions
What is the difference between hypertrophic and oligotrophic non-union?
In hypertrophic non-union there is a lot of callus formation (it is a highly vascular fracture site), and in oligotrophic there is not a lot
What are the 4 types of non-viable non-union?
- Dystrophic
- Necrotic
- Defect
- Atrophic
Define dystrophic non-viable non-union
Non-union where blood supply is insufficient
Define necrotic non-viable non-union
Non-union where there is necrotic tissue in the fracture site
Define defect non-viable non-union
Non-union where there is a bone defect at the fracture gap
Define atrophic non-viable non-union
Non-union where there is no evidence that its attempted to heal, and bone ends appear sclerotic and atrophied
What are 3 sequale to atrophic non-union?
- Medullary cavity seals over
- Fracture gap fills with fibrous tissue
- Pseudoarthrosis formation
How would you treat atrophic non-union?
Debride fracture ends until you get to viable bleeding bone, open the medullary cavity, and stabilise with plate and screws
