Lecture 35 4/22/25 Flashcards by Danika Boltz

What are the characteristics of incomplete ossification?

-occurs in premature and dysmature foals
-related to delayed development and/or fescue-induced placentitis
-can coincide with neonatal maladjustment syndrome and failure of passive transfer
-cuboidal bones of carpus and tarsus are most at risk
-can cause angular limb deformities

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What is the presentation of incomplete ossification?

-dysmature or premature foal
-not usually painful/lame
-can be lame if joint sepsis is concurrent
-can be non-ambulatory

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What is the treatment for incomplete ossification?

-CONTROLLED exercise/rest
-prevent cartilage damage from overuse
-splints or casts if unstable
-time to ossify/heal

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What is the prognosis for incomplete ossification?

-depends on severity
-grade 4 is the least severe and has a good to excellent prognosis for athletic use
-grade 1 is the most severe and has a poor to guarded prognosis for athletic use

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What is the presentation of an angular limb deformity?

-typically normal foal
-sound +/- mechanical lameness
-deformity secondary to physitis or incomplete ossification

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What are the characteristics of angular limb deformity?

-deviation in limb conformation in the frontal/coronal plane
-named based on the directionality of the distal segment
-“valgus” if deviation is lateral
-“varus” if deviation is medial

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What are the treatment windows for angular limb deformity based on affected portion of the limb?

proximal P1: 0 to 2 months of age
distal third metacarpus/tarsus: 0 to 2 months of age
distal radius: 0 to 6 months of age
distal tibia: 0 to 4 months of age

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What is the conservative management for mild angular limb deformity?

corrective foot trim/extension (toe in trim in, toe out trim out)

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What are the characteristics of surgical management of angular limb deformity?

-done for moderate to severe cases
-need to refer early; need to treat before physis closure
-surgical implant is placed on LONG side to hold physis while short side grows to catch up
-must remove implants at desired conformation to prevent overcorrection

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What is the prognosis for angular limb deformity?

-depends on severity and age of foal
-mild to moderate cases have a good to excellent prognosis for sport
-prognosis decreases with increasing severity and age

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What are the characteristics of flexural limb deformity?

-occurs in the sagittal plane
-due to persistent hyper- or hypoflexion of a limb
-hyperflexion results from contraction
-hypoflexion/hyperextension results from laxity
-named according to the joint involved
-can be present at birth or develop with growth

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Which joints commonly experience contracture/hyperflexion?

-metacarpophalangeal joint (SDFT)
-distal interphalangeal joint (DDFT); aka Club Foot

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Which joints commonly experience laxity/hyperextension?

-metatarsophalangeal joint
-hind limb

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What are potential contributing factors to flexural deformities present at birth?

complex and multifactorial
-uterine positioning
-acquired disease of mare during pregnancy
-exposure of mare to certain forages
-genetic causes

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What are the characteristics of congenital hyperflexion?

-often causes dystocia
-most commonly involves distal interphalangeal joint and metacarpophalangeal joint

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What are the treatment steps for congenital hyperflexion?

-supportive bandage +/- splint or cast
-assistance when standing and nursing
-stretching
-pain control/NSAIDs
-possibly systemic oxytetracycline (promotes laxity but very toxic)

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When does acquired hyperflexion typically develop?

around 3 to 12 months of age, due to rapid growth in the foal

What are the treatment steps for acquired hyperflexion?

-therapeutic shoeing/trimming
-pain control/NSAIDs
-stretching and controlled exercise
-desmotomy
*distal/inferior check lig. for DDFT/DIP joint
*proximal/superior check lig. for SDFT/MCP joint

What are the characteristics of digital hyperextension?

-very common
-caused by flexor muscle flaccidity
-self corrective; treated with exercise and strengthening
-supportive care includes heel extensions and preventing skin damage

What are the characteristics of hindlimb laxity?

-leads to “windswept” foals
-controlled exercise allows for strengthening without damaging cartilage under abnormal load

What is the presentation of septic physitis/arthritis?

-lameness
-regional swelling or joint effusion
-possibly febrile
-possible history of failure of passive transfer

What is involved in a septic physitis/arthritis workup?

-complete physical
-CBC
-look for source of infection (hematogenous spread to joint)
-radiographs
-joint fluid analysis

What are the clin path signs of synovial sepsis?

WBC count greater than 100,000 WBC/uL
-greater than 90% neutrophils
-TP greater than 4 g/dL

What is the treatment for septic physitis/arthritis?

systemic antibiotics
-regional antibiotics
-daily lavage of synovial structures
-serial rads to assess for osteomyelitis

What is the prognosis for septic physitis/arthritis?

-depends on severity of concurrent bone change or angular limb deformity -good prognosis for athletics and excellent prognosis for life if caught early and treated aggressively -decreased prognosis with concurrent osteomyelitis -decreased prognosis with prolonged infection

What is OCD?

-inflammation of bone and cartilage due to presence of loose fragments -fragment present due to disruption of endochondral ossification

What are the theories for OCD formation?

1. vascular damage prevents ossification and thus a fragment is separated from parent bone 2. direct trauma to ossifying bone creates a small area of necrosis

What are the most common joints for OCD?

-tibiotarsal -femoropatellar -metacarpo(tarso)phalangeal *can be any diarthrodial joint*

What is a diarthrodial joint?

2 bones covered by articular cartilage, connected with joint capsule, that is lined by synovium

What is important regarding the assessment of OCD?

should always radiograph both sides to identify bilateral occurrence

Where does OCD most commonly occur within the metacarpo(tarso)phalangeal joint?

proximal sagittal ridge

Where does OCD most commonly occur within the tibiotarsal joint?

-distal intermediate ridge of tibia -lateral trochlear ridge -medial malleolus

Where does OCD most commonly occur within the femoropatellar joint?

-lateral trochlear ridge -medial trochlear ridge

What is the treatment for OCD?

-typically surgical removal -some heal with time -joint supplements/adequan -may be able to ignore if small, non-displaced, and not symptomatic

What is the prognosis for OCD?

-depends on size, location, and degree of concurrent joint damage -good for athletics -excellent for life

What is a subchondral bone cyst?

-fluid filled cavity within subchondral bone plate -damage to cartilage allows joint fluid into space -bone inflammation results in extravasation of fluid

What are the theories for subchondral bone cyst formation?

1. vascular damage prevents ossification and thus a fragment is separated from parent bone -direct trauma to ossifying bone creates a small area of osteonecrosis

What is the most common location for subchondral bone cyst formation?

medial femoral condyle

What are the treatment options for subchondral bone cysts?

-transcondylar screw to stabilize the "bridge" of bone and allow cyst to fill in -debride cyst and fill with polymer or matrix -inject cyst with stem cells -inject cyst with corticosteroids -inject joint with corticosteroids

What determines whether OCD or a subchondral bone cyst forms?

-SBC forms in/on weight-bearing surfaces -OCD can occur anywhere but typically does not occur in areas of weight-bearing