14 – Musculoskeletal Conditions

Question 1

MSK problems can be specific or generalized

Answer 1

• Specific
  o One site (ex. fracture)
  o Bilateral (ex. elbow dysplasia in dogs)
• Generalized
  o Muscular dystrophies
  o Infectious polyarthritis (Ex. Lyme disease)
  o Tendon weakness secondary to hyperadrenocorticism

Question 2

Exam

Answer 2

• General physical exam: rule out systemic conditions
• Orthopedic exam
  o Include the spine
  o Do a full exam even if you find one problem, there may be more than one
• Neurological exam
• Points of confusion:
  o Neurological disorders can result in weakness
  o Pain from pyelonephritis could appear like back pain

Question 3

Gait definition

Answer 3

• Commonly used patterns of locomotion consisting of a series of repeated strides

Question 4

Stride definition

Answer 4

• Cycle of movement where each limb goes through a step cycle

Question 5

What is the stance phase?

Answer 5

• Period in which foot is in contact with ground
  o First part: braking
  o Second part: propulsion

Question 6

What is the swing phase?

Answer 6

• Period in which foot is in the air

Question 7

Symmetric gaits

Answer 7

• Right and left sides of body move symmetrically
• Ex. walk, trot, pace
• *most commonly used for gait analysis

Question 8

Asymmetric gaits

Answer 8

• Right and left sides of body move differently
• Ex. canter, gallop
• *less commonly used for gait analysis
  o But some problems are only seen at these gaits
• **different horse breeds can have different gaits

Question 9

Walking gait

Answer 9

• 4 beat gait
• LH, LF, RH, RF

Question 10

What does tracking mean? (used in horses at both walk and trot)

Answer 10

• Hind foot lands in the same spot as the front foot
• *over tracking means the hind foot reaches PAST where the front foot landed
  o Some horse people want them to do that=getting long strides

Question 11

Trot gait

Answer 11

• 2 beat gait
• Legs move in diagonal pairs
• RF, LH move together, LF, RH move together
• *most common gait used for gait analysis

Question 12

Pace gait

Answer 12

• Not commonly used for gait analysis
• 2 beat gait symmetrical
• Some dogs pace naturally
• Pace may be seen in some dogs with fatigue or orthopedic problems
• RF, RH move together, LF, LH move together
• *horses: only in some standardbred race horses (harness racing)

Question 13

Canter/gallop gait

Answer 13

• Same pattern of movement but gallop has a suspension phase where there is NO contact with the ground
• Can be either on left lead or right lead
  o Refers to which forelimb comes farthest forward
• When on a turn, animal should lead with the inside forelimb (unless trained differently)
• *in horses: hindlimbs should be on same lead as the front limbs

Question 14

Disunited or cross canter (horses)

Answer 14

• If front and hind limbs are on opposite lead
• Can be seen intermittently in young horses or those starting training that lack balance
• *could indicate a problem if seen in a horse that previously cantered normally

Question 15

Dogs: canter/gallop

Answer 15

• Hindlimbs can be on same side as forelimbs (transverse gallop) OR on opposite lead (rotary gallop)
• *BOTH are normal in dogs

Question 16

How do you ID a lame leg?

Answer 16

• Observe stance
  o Look for decreased weight-bearing (observe digits in dogs, horse may rest a front leg, weight shifting)
• Observe walk
• Observe trot if not obvious at walk
• *if problem only seen at canter=observe canter or have owner bring videos if not possible to observe

Question 17

IDing a lame leg: walk and trot (VIDEOS)

Answer 17

• Front leg lameness: watch for head nod (“Down for sound=ouch”)
• Hind limb lameness: watch for hip hike (horses) (“down for sound”, higher on sore side)
• Both front and hind:
  o Watch for shorter stride length on lame leg
  o Watch for decreased stance time on lame leg

Question 18

What can you do if lameness is still not obvious?

Answer 18

• Try circling in both directions
• Try inclined or declined walking
• Dogs: may be able to take them up and down stairs (‘make them sore’)
• Cats: videos from home
• Consider tools for lameness diagnosis if available

Question 19

What are some tools for lameness detection?

Answer 19

• Stance analyzer: measures static weight distribution
• Pressure walk ways
• EMG
• Hoof system
• Instrumented treadmills (more research based)
• Accelerometer/gyroscope sensors attached to 1 forelimb and 1 hindlimb (can determine stance time and swing time)
• Equinosis lameness locator (3 sensors: head, lumbar spine, front foot)

Question 20

Pressure walkways

Answer 20

• Made up of many pressure sensors
• Larger size allows recording of multiple foot falls in a single trial
• Can record both sides of the body simultaneously
• Records changes in pressures

Question 21

EMG

Answer 21

• Used to detect activity of specific muscles during locomotion
• Indwelling EMG uses thin wires within specific muscles
• Surface EMG uses metal discs or bars attached to skin over large superficial muscles
• *common in people, more challenging in animals

Question 22

Hoof system

Answer 22

• Wireless pressure sensors used on bottom of the hoof

Question 23

What are some diagnostic tests for MSK conditions?

Answer 23

• Hoof testing
• Flexion tests
• Nerve blocks and joint blocks
• Various lab work
• Imaging modalities

Question 24

Hoof testing

Answer 24

• Can ID area of hoof pain
  o May want to check all hooves, not just lame leg
  o Start with non-lame foot first to gage how they respond

Question 25

Flexion tests

Answer 25

• For horses: may exacerbate a lameness
• Can help ID painful site
• Caution as can be positive with underlying conditions

Question 26

Nerve blocks and joint blocks

Answer 26

• Used to block pain at a specific site
• Helps localize the lameness
• Work distal to proximal
• Common in horses
• Joint blocks occasionally used in dogs (if ID problems in 2 joints, but want to ID the main issue)

Question 27

What are examples of lab work for MSK conditions?

Answer 27

• CBC: infectious/inflammatory
• Chem: electrolyte abnormalities , CK/AST for muscle damage
• Specific test: ex. Cushings, 4Dx for tick borne disease
• Joint tap
• Genetic tests
• Muscle biopsy
• Bone biopsy
• EMG: ex. myotonia

Question 28

Imaging modalities

Answer 28

• Radiographs: good for bone
• Ultrasound: good for soft tissue (ligament tears: 0=normal, 3=marked)
• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
• Nuclear scintigraphy
• Thermography
• Positron emission tomography (PET)-CT

Question 29

CT MSK uses

Answer 29

• *3D x-ray
• Joint conditions
• Complex fractures
• IVDD

Question 30

MRI MSK uses

Answer 30

• Soft tissue injuries
• Spinal cord
• Nerves
• Brain

Question 31

Nuclear scintigraphy

Answer 31

• Some types of bone or soft tissue injuries OR where pain location can not be IDed
• Radioisotope is injected, absorbed by exposed hydroxyapatite and detected with a gamma camera
• Can help determine location for further imaging

Question 32

Thermography

Answer 32

• Thermal camera used to detect areas that are abnormally warm or abnormally cool

Question 33

Positron emission tomography (PET) -CT

Answer 33

• After walking the patient for 15 mins, anesthesia is induced and CT scans are performed before and after injection of a radioisotope
• *it accumulates more in areas of increased glucose metabolism, which can include areas of inflammation