Joints and Lameness: Arthrocentesis, Septic arthritis, Lameness, OA Flashcards
What type of needle (gauge and length) is typically used for arthrocentesis?
20G 1”
Why is physical restraint preferred to chemical restraint for arthocentesis?
Drugs renduce inhibition so horse can react more rapidly and exagerated when needle goes in
Left forelimb: What structure(s) are indicated by #13? #14?
13: Extensor brnach of interosseus
14: Flexor tendons
What limb is this (fore or hind)? What is indicated by #1, #2, #3, and #6?
Forelimb (lateral view)
1: Large metacarpal bone (MC III)
2: Proximal sesamoid bones
3: Proximal phalanx
6: Navicular bone
What are the landmarks for performing a radiocarpal joint arthrocentesis?
Distal medial ridge of the radius
Proximal edge of the radiocarpal bone
With which joint does the carpometacarpal joint communicate?
Middle/Inter carpal joint
With which joint does the tibiotarsal joint communicate?
Proximal intertarsal joint
What landmark do you palpate for a tibiotarsal joint arthrocentesis?
Medial malleolus of tibia
You know the drill
Blue: Common digital extensor muscle
Pink: Superficial digital flexor tendon
Aqua: Deep digital flexor tendon
Green: Common digital extensor tendon
This bone is one landmark used to ID the radiocarpal joint. Identify the bone indicated.
a. Third carpal bone
b. Ulnar carpal bone
c. Metacarpal IV
d. Radial carpal bone
d. Radial carpal bone
What is the preferred approach to the metacarpophalangeal joint?
Collateral sesamoidean ligament approach
How many compartments does the stifle joint have? What are they? Which should you inject when treating the stifle?
3
Femoropatellar joint
Medial femorotibial joint
Lateral femorotibial joint
Inject all compartments
Which which compartment does the femoropatellar joint communicate with more often?
MFT
Describe the pathogenesis of septic arthritis.
Decreased HA synthesis
Loss of PG
Joint effusion
Pain
Compromise synovial blood flow
What are the types of septic arthritis is foals? What is involved in each type?
S, E, and P
S: Synvoial structures (membrane, fluid)
E: Epiphysis
P: Physis of long bones +/- joint
Which type of septic arthritis in a foal is highly effusive and typically affects multiple larger joints?
S-type
Which type of septic arthritis in foals occurs at a few weeks of age usually following another disease such as pneumonia or diarrhea? How does the lameness present?
E-Type
Mild lameness followed by acute exacerbation (“Lame on and off and then suddenly super lame”)
Which type of septic arthritis in foals presents with swelling but no effusion? How many sites are usually affected?
P-type
One site (e.g. distal physis of MCIII/MTIII, radius, tibia)
What should you evaluate and how in addition to the joints in a foal with septic arthritis?
Umbilicus
Ultrasound
Which bacterium is usually associated with iatrogenic septic arthritis in adult horses? Traumatic septic arthritis?
Staphylococcus
Enterobacteriaceae
T/F: An open joint is only considered infected if there is effusion.
False, an open joint is always an infected joint
What is involved in foal septic arthritis that is usually not involved in adults?
Bone
What is the gold standard for diagnosing sepsis?
Microbiology
What is the normal TP in synovial fluid?
<2.0 g/dL
>3.5 g/dL is abnormal
What are the 2 requirements for successful treatment of septic arthritis?
Rapid recognition of disease
Immediate aggressive treatment
What is the mainstay of treatment for septic arthritis?
Lavage
Early and often with large volumes (5-10L) and large G needle (16-18)
How should antibiotics be administered for septic arthritis?
Local is vital
How long should you leave the tourniquet when performing regional limb perfusion? What dosage is usually used?
30 min
1/3 of systemic dose
What is usually the cause of lameness?
Pain
How many steps are there for a classical lameness exam? What are they?
7
1: History
2: PE
3: Palpation (weight-bearing and non + Hoof testers)
4: Observation at exercise
5: Flexion tests
6: Diagnostic nerve blocks
7: Diagnostic imaging
What is the gait lameness is graded from?
Trot
If a horse is dropping his head every time the left forelimb hits the ground, where is he lame?
Right forelimb
At what grade of lameness may you see a head and neck nod with a hindlimb lameness?
3/5 or above
What parts of the hoof are tested with hoof testers?
Wall (all the way a ound)
Sole
Frog (across)
Heels
Coronary band
T/F: Stringhalt is a type of lameness caused by pain.
False, it is a gait abnormality
What grade of lameness is consistently observable at a trot under all circumstances?
Grade 3
You are evaluating a horse that only shows signs of lameness when trotting in a circle. What grade is this lameness?
Grade 2
What are the 5 pathognomic lameness’ diagnosed at the walk?
Peroneus tertius rupture
Locking patella
Stringhalt
Fibrotic myopathy
Sweeny
What muscles are usually affected by fibrotic myopathy?
Semimembranosus
Semitendinosus
What is possible in a horse with peronius tertius rupture that a healthy horse cannot do?
Full extension of the hock with flexion of the stifle (Paradoxical hindlimb movement)
What are 3 treatment options for locking patella?
Medial patellar desmotomy
Walking backwards
Strengthening quadriceps muscles (Climb hills)
What is stringhalt?
Hyperflexion of the hock
During a lamenss exam you notice a shortened cranial phase of the stride and a characteristic ‘slapping’ sound when one of the hindlimbs hits the ground. What is your top DDx? How could palpation aid in the diagnosis?
Fibrotic myopathy
There is a palpable firmness of the affected muscle
Damage to which nerve resulting in the atrophy of which muscle causes Sweeny?
Suprascapular nerve
Infraspinatus muscle
T/F: During a flexion test, the horse should be trotte din a straight line and circle to assess it’s gait.
False, straight line immediately after flexion
How long do you hold a flexion test for the proximal joints of the forelimb? Distal joints?
Proximal 30sec
Distal 60sec
Which joints are being flexed during this fore and hindlimb flexion test?
Fetlock
Pastern
Coffin
Distal limb
Which joints are being flexed during this forelimb flexion test?
Carpus
Cubital (elbow)
Glenohumeral
Distal limb
How long do you hold a flexion test for the proximal joints of the hindlimb? Distal joints?
Proximal 90 sec
Distal 30 sec
Which joints are being flexed during this flexion test?
Hock (tarsus)
Stifle
Coxofemoral
Proximal hindlimb
Why do you begin distally and work proximally when using local anesthesia to localize the lameness? In which direction do you direct the needle? Why?
AX numbs everything from the injection site down
Distally to minimize proximal diffusion
Which agent is prefered for local anesthesia? How long does it last?
2% Mepivacaine (Carbocaine)
30min- 2hrs
Preferred to lidocaine because lidocaine stings
Why is 0.5% bupivicaine not used for diagnostics?
It lasts too long (5-6 hours)
What is the most distal nerve block that can be done in the horse?
Palmar digital
Blocking palmar digital nerves
Which nerves are blocked with the abaxial/basisesamoid nerve block?
Palmar digital nerves
Which nerves are blocked by the 4-point block?
L/M Palmar metacarpal nerves Or Metatarsal if hindlimb
L/M Palmar nerves
Where are the needles placed for a 4-point nerve block?
Between Palmar MC III and MC II and MCIV - right at the button of the splint bones
Between the suspensory ligament and the DDFT - avoiding (by going proximal to it) DDF tendon sheath
When performing a low 4-point nerve block, what nerves are being blocked by the needle placed distally and more dorsally?
a. Palmar nerves
b. Palmar metacarpal nerves
c. Palmar digital nerves
d. Ulnar nerve
b. Palmar metacarpal nerves
At level of button of the split bone
The origin of which structure is blocked by the lateral palmar nerve block?
Suspensory ligament
Lameness that does not improve with PD or abaxial nerve blocks, but shows marked improvement with low 4-point block is likely localized to which area?
a. Cubital joint
b. Metacarpophalangeal joint
c. Proximal interphalangeal joint
d. Carpometacarpal joint
b. Metacarpophalangeal joint
* Fetlock*
When preforming IA anesthesia, how much volume of anesthetic should you infuse in relation to the volume of fluid injected?
a. Equal volume
b. Injected volume less than or equal to the volume collected
c. Injected volume more than or equal to the volume collected
d. 50cc
c. Injected volume more than or equal to the volume collected
Slightly distend joint
How many views are required for examing distal joints? Which views?
4 views
2 obliques
1 lateral
1 DP
What is the only modality that allows for real time evaluation of both soft tissues and to some extent, bone?
Ultrasound
What is the modality of choice for imaging bone?
CT
What component of the synovial membrane allows for phagocytosis? Which produce hyaluronic acid and collagen?
Type A -Macrophages
Type B -Fibroblasts
What portion of the joint absorbs shock?
a. Synovial membrane
b. Subchondral bone
c. Articular cartilage
b. Subchondral bone
Which condroprotective agent is a long unbranched non-sulfated GAG which originates from type B synoviocytes and chronocytes? The drug is chrondroprotective when administered IA, provides analegsia and reduces cartilage fibrillation, when used appropraitely.
Sodium Hyalurinate / Hyaluronan / Hyaluronic Acid / HA
What can you combine with HA in order to decrease inflammation?
Triamcinolone (IA)
T/F: Generic and brand name chrondroprotectants have very similar if not idential efficacy.
False, brand name is better (e.g. Adequan)
PSGAGS (e.g. Adequan) significantly potentiate subinfective doses of bacreria. What can you do counteract this?
a. Combine with Triamcinolone IA
b. Combine with NSAID IA
c. Combine with Amikacin IA
d. Only administer PSGAGS IV
c. Combine with Amikacin IA
125mg
T/F: Polyglycan can be administered IV or IA, but is less effective IV.
False, IV causes increase in disease progression
Which chondroprotective has a greater effect on articular cartilage fibrillation?
HA
Which chondroprotectant has a greater magnitude of postive effects on the synovial membrane?
PSGAG
Which corticosteroid has consistently shown to have deleterious effects on articular cartilage and so should not be used IA?
Methylprednisolone acetate
