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Equine Final Year > Developmental Orthopaedic Disease 2 > Flashcards

Developmental Orthopaedic Disease 2 Flashcards

1
Q

What is an angular limb deformity?

A

Deviation in the long axis of the limb - really to do with angulation of bones primarily

Can be congenital or acquired

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2
Q

Where are the 3 main sites for an angular limb deformity in the foal?

A

MCP and MTP (fetlock) joints

Carpus

Tarsus

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3
Q

What is a VALGUS limb deformity?

A

Limb deviates laterally distal to the site of the deformity

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4
Q

What is a VARUS limb deformity?

A

Limb deviates medially distal to site of deformity

Orientated medially, towards the inside

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5
Q

Which type of deformity is this?

A

Carpal VALGUS

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6
Q

Which type of deformity is this?

A

Tarsal VALGUS

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7
Q

Is a valgus or varus limb deformity more common?

A

Valgus more common than varus

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8
Q

What is significant about angular limb deformities in very young foals?

A

In very young foals, when they have 0 muscles around shoulders when they are young, often they will have acceptable or WNL limb deformity –they will grow out of it –need to identify which will auto correct and which need assistance.

Accept valgus of carpus of up to 4-5 degrees – this is considered acceptable

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9
Q

What are some congential causes of angular limb deformities in foals?

A
  • Periarticular laxity –this can be a cause of ALD –soft tissue around these joints are loose and cannot hold limb as it should be held
  • Incomplete ossification of carpal/ tarsal bones
    • Premature/ dysmature/ twin foals
    • Untreated will lead to carpal valgus/ tarsal collapse/ tarsal valgus
    • Permanent conditions – do NOT want an incomplete ossification to progress to an ALD
  • Epiphyseal dysplasia
  • Abnormal intra-uterine positioning
    • ‘windswept’ foal –look at foal from side, it looks like entire foal is ‘wonky’, all legs loo
    • caused by abnormal positions. Can usually correct up a certain amount

Mild bilateral carpal valgus (2°-5°) and toed-out conformation at birth extremely common and usually resolves spontaneously

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10
Q

Which foals is incomplete ossification of carpal/tarsal bones common in?

A

Premature or dysmature or twin foals

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11
Q

What can untreated incomplete ossification of carpal/tarsal bones lead to?

A

Untreated will lead to carpral valgus/tarsal collapse/tarsal valgus

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12
Q

What is the pathogenesis of ACQUIRED angular limb deformities?

A
  • ‘Inverted –U’ relation ship between growth rate and load
  • Excessive compression on one aspect
    • Contralateral limb lameness
    • Poor conformation
    • Excessive bodyweight/ exercise
  • Physeal trauma/ fracture
  • Unbalanced nutrition
  • (Osteochondrosis)
  • Less compression than normal -> decreased growth rate •Increased compression (within physiological range) -> increased growth rate
  • Increased compression (pathological) -> decreased growth rate
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13
Q

How can you go about assessing an angular limb deformity?

A
  • Stand directly in front of affected joint
    • ‘Fetlock’ often easier with limb lifted
    • Really look if carpus is deviated laterally
  • Manipulate limb
    • If manual correction possible => periarticular laxity or incomplete ossification
    • If not => originates in osseous structures
    • Important to differentiate between periarticular laxity and proper ALD –if able to push the deviation back or correct it to a certain degree, most likely due to periarticular laxity –if you cannot change it, it is because it is due to ALD deformity.
  • In motion
    • Additional rotation may indicate compensatory problem
  • Radiography
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14
Q

How can you differentiate between periarticular deformity and an angular limb deformity?

A

If manual correction possible => periarticular laxity or incomplete ossification

If not => originates in osseous structures

Important to differentiate between periarticular laxity and proper ALD – if able to push the deviation back or correct it to a certain degree, most likely due to periarticular laxity –if you cannot change it, it is because it is due to ALD deformity.

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15
Q

How should you take a radiograph when looking for angular limb deformities?

A
  • Long, narrow cassettes –want to try and have as much bone proximal and as much bone distal as the deviation
  • True Dorsopalmar
  • When you go and see a foal for ALD, take a DP but also lateral and medial as then you can look for the persistence of an ulnar (which can cause a deviation –they get an ossified ulnar that sticks around when it shouldn’t)
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16
Q

When looking at a radiograph for an angular limb deformity - what should you evaulate?

A

Evaluate

  • Degree of ossification of cuboidal bones
  • Shape of all skeletal components
  • Angle of deviation
  • Pivot point (1 y site of deformation)
    • Pivotpoint–identify the location of the deformity, or where it came from. Get here by drawing lines –one straight in middle of proximal bone and one in middle of distal bone –where they meet, this is the origin of the ALD.
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17
Q

If on a radiograph of a foal with a suspect angular limb deformity - if the skeletal components are all normal, what can you assume?

A

Is skeletal components all normal - assume periarticular laxity

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18
Q

What is the angle of deviation and point of intersection on a radiograph on a foal with suspected angular limb deformity?

E.g. how do you do it and what does it show?

A
  • Use long cassette so we can ensure we have enough bone to trace the 2 lines.
  • Bisect long bones either side of deviation
  • Point of intersection defines origin of deformity
    • e.g. physis, cuboidal bones
  • Measure angle of deviation
    • Objective estimate of severity
    • Allows comparison with follow-up radiograph
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19
Q

Describe the following radiographs with regards to are they normal, is there incomplete ossificaiton etc?

A
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20
Q

What is the treatment for CONGENITAL angular limb deformities?

A
  • ‘Wait and see’ sometimes not an option
    • Radiograph carpus and tarsus if
      • <310 days gestations
      • Dysmature (silky coat, floppy ears, domes forehead)
      • Congenital ALD
  • Periarticular laxity & normal ossification. With this, would want to do the following:
    • Box rest and controlled exercise (10-20min/d)
      • Controlled exercise is important
    • Monitor closely –several times a week
    • Increase exercise gradually once angulation normalised and correcting in right direction
    • Good prognosis if managed well and early
  • for insufficient ossification –its not going to work to do controlled exercise, some sometimes can leave foal in stall and keep eye on it or some people will just euthanise them as they might often arise with other problems. Have seen cases with rounded bones where you wait and its fine, but if there’s no bones at all –prognosis isn’t great
  • External coaptation - splint or tube cast
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21
Q

If you have periartiuclar laxity and NORMAL ossification - how can you treat this?

A
  • Periarticular laxity & normal ossification. With this, would want to do the following:Box rest and controlled exercise (10-20min/d)
    • Controlled exercise is important
    • Monitor closely –several times a week
    • Increase exercise gradually once angulation normalised and correcting in right direction
    • Good prognosis if managed well and early
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22
Q

If you have insufficient ossification with an angular limb deformity, what are your treatment options?

A

for insufficient ossification –its not going to work to do controlled exercise, some sometimes can leave foal in stall and keep eye on it or some people will just euthanise them as they might often arise with other problems. Have seen cases with rounded bones where you wait and its fine, but if there’s no bones at all –prognosis isn’t great

  • Strict box rest
  • Maintain axial alignment
  • These horses are at risk of collapsing joint completely
    • need additional support such as Bandage, Tube cast or Splint
  • Monitor radiographically ~q2w –
  • Remove support once sufficient ossification
  • Good prognosis if managed well and early
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23
Q

How can you use external coaptation (splint/tube cast) to treat congenital angular limb deformities?

A
  • External coaptation(splint/ tube cast)
    • Generally contraindicated unless severe or incomplete ossification
      • soft tissue laxity
    • Tube cast: leave foot out –want limb to load a little bit
      • limits flexor laxity
    • Intermittent splinting (12h on 12h off) an option – trying to stop risk of laxity
    • Pressure necrosis major risk in foals
      • change bandage q3-4d, cast q10-14d
      • Needs to be changed really quickly, 3-4d in very young foals and every 10-14d in older foals
  • DO NOT PUT A CAST ON A FOAL THAT HAS PERIATICULAR LAXITY –if its kept immobilise for too long, will make it more lax –needs controlled exercise e.g. hand walking
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24
Q

What should you not do to a foal that has periarticular laxity?

A

Do NOT put a cast on these foals

Will make it become more lax!

Needs controlled exercise

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25
Q

When putting a cast or a tube splint on a foal that has an angular limb deformity - why should you leave the foot out?

A

Leave the foot out as you want the limb to load a little bit

26
Q

What is a massive risk in foals with splinting and casting?

How can you overcome this?

A

pressure necrosis

Change bandaage regularly - every 3-4d in very young foals and every 10-14d in older foals

27
Q

What is the surgical treatment for ACQUIRED angular limb deformity?

A
  • ‘Periosteal stripping’ => speeds growth –quite easy to do and quick
  • Transphysealbridging => slows growth –can be one 2 in 2 ways, can place screw from metaphysis through physis –make physsicollapse for a bit and decrease growth rate. Or can place 2 screws and attach with wire –implants are removed when needed.
  • (Osteotomy/ ostectomy)
28
Q

What is the conservative treatment for ACQUIRED angular limb deformity?

A
  • Correct inciting factors (lameness, diet etc)
  • restricted exercise
  • corrective trimming/shoeing
29
Q

When treating an ACQUIRED angular limb deformity, what does the choice of treatment depend on?

A

Choice of treatment: depends on degree of deformity and remaining growth potential in relevant physis (age of foal) as eventallygrowth palteswill close and if they close before you fix the ALD –the ALD will remain forever

30
Q

Does periosteal stripping (as a treatment for aquired ALD) speed up or slow down the growth of the bones?

A

Periosteal stripping SPEEDS THE GROWTH

31
Q

Does transphyseal bridging (as a treatment for aquired ALD) speed up or slow down the growth of the bones?

A

Transphyseal bridging - SLOWS GROWTH

32
Q

What is periosteal stripping also known as?

How does it work?

A
  • hemi-circumferential periosteal transection and elevation (HCPTE) – a.k. periosteal stripping
  • Speeds growth; effect may be mechanical or via upregulation of local feedback loop (Ihh, etc)
  • Valgus, operate on lateral side of physis; varus, medial
33
Q

Do you do HCPTE (periosteal stripping) or transphyseal bridging on the short side?

A

HCPTE - on the short side - increases growth

Transphyseal bridging - on the long side - slows growth

34
Q

What are the benefits and negatives of using periosteal stripping (HCPTE) to fix an angular limb deformity?

A
  • Simple
  • No implants
  • No 2nd surgery
  • Over-correction rare
  • ~80% success rate
  • Effect time-limited (~1-2m)
  • Limited ability to correct at later time points because you only rely on the inner capacity of the physis to grow again – timing is everything with ALD
35
Q

What are the benefits and negatives of using transphyseal bridging to fix an angular limb deformity?

A
  • More aggressive
  • Involves implants
  • Requires 2nd surgery as you cannot leave the implants in forever, will send the legs the other way!!
  • Risk of over-correction if the people don’t monitor horse close enough
  • Indicated at later time points
  • Need careful monitoring
36
Q

What is the prognosis of congenital and acquired angular limb deformities in foals?

A
  • Excellent if corrects fully
  • May be prone to lameness if residual ALD
  • Especially if there is a component of incomplete ossification
37
Q

What is the prevention for congenital and acquired angular limb deformities?

A
  • Immediate diagnosis and appropriate management
  • Aggressive treatment of any lameness
  • Balanced nutrition, maintenance of appropriate condition score
38
Q

Which joints are most commonly affected in foals with a CONGENITAL FLEXURAL limb deformity?

A
  • Congenital
    • Carpus and MCP most common
    • Tarsus, MTP, PIP & DIP joints less common
39
Q

Which joints are most commonly affected in foals with a ACQUIRED FLEXURAL limb deformity?

A
  • Acquired
    • DIP & MCP most common
    • MTP & PIP less common
    • Often the coffin and fetlock joint most affected
    • Sudden growth spurt where the bones grew but the soft tissue didn’t follow speed of growth – results in flexural limb deformity
40
Q

What is the pathogenesis for a congenital flexural limb deformity?

A
  • Usually unknown
  • Intrauterine malpositioning
  • Disparity in mare to foal size
  • Teratogens
41
Q

What is the pathogenesis for an acquired flexural limb deformity?

A
  • Pain in affected limb
  • Overnutrition & rapid growth
    • Disparity between bone and soft tissue growth
  • Genetic predisposition
42
Q

What are the clinical signs for a congenital flexural limb deformity?

A
  • Usually bilateral
  • May cause dystocia
  • If severe may be unable to stand, ambulate or suckle
  • ± Common digital extensor tendon (on dorsla aspect of forelimb and attaches onto P3) rupture – often quite frequent – sometimes its so tight due to contraction it will rupture
43
Q

What are the clinical signs for an acquired flexural limb deformity?

A
  • Uni- or bilateral
  • DIP joint
    • Mainly foals & weanlings
    • ‘Club’ foot
    • Concave dorsal wall
    • ± remodelling of P3
  • MCP joint
    • Mainly yearlings
    • Upright fetlocks
    • Hoof can look normal
44
Q

What is the assessment for a flexural limb deformity?

A
  • Observe stance and ambulation
  • Manipulate limb
    • Determine degree of correction possible
  • Palpate limb (weight-bearing & flexed)
    • Determine structures involved
  • Determine stage
    • Stage I: dorsal hoof wall not yet vertical
    • Stage II: dorsal hoof wall beyond vertical – horse almost walking on toe, fetlock will knuckle over with weight on foot, cannot put fetlock back into position
  • Diagnose any 1y or associated lameness
45
Q

What are the 2 stages for a flexural limb deformity?

A

–Stage I: dorsal hoof wall not yet vertical

–Stage II: dorsal hoof wall beyond vertical – horse almost walking on toe, fetlock will knuckle over with weight on foot, cannot put fetlock back into position

46
Q

What is the treatment for a congenital flexural limb deformity?

A
  • Mild (able to ambulate) usually resolve spontaneously
  • Interventions:

–Physiotherapy

–Controlled exercise

–Heavy bandage/ splint/ brace/ cast

  • Splints can be effective for short periods of time
  • Watch for pressure sores!!!

–i/v tetracycline daily or every other day 3-4x – people have been thinking that it helps with contraction due to circulation of calcium, but this is currently under debate and questionable

–Consider NSAIDs ± gastric protectants due to foal stomach and more prone to side effects of NSAIDs

–Farriery

47
Q

What is the theory for using IV tetracycline to treat a congenital flexural limb deformity?

A

i/v tetracycline daily or every other day 3-4x – people have been thinking that it helps with contraction due to circulation of calcium, but this is currently under debate and questionable

48
Q

What is the treatment for an acquired flexural limb deformity?

A
  • Treat any 1y lameness
  • Reduce and balance nutrition (early weaning)
  • Farriery

–Heel

–± toe extension

  • Moderate exercise
  • Analgesics ±gastric protectants
  • Cast incorporating foot => relaxes MTU
  • Oxytetracycline?
  • Surgery

DIP joint: rasp heel frequently

MCP joint: heel wedge to relax flexor tendon and change MCP joint angle

49
Q

What is the surgical treatment for a flexural limb deformity with the DIP joint?

A
  • Stage II or no improvement in 4-8 weeks
  • Accessory Ligament of DDFT desmotomy – will help predominantly dor DIP and maybe fetlock a bit
  • ± DDFT tenotomy
  • Combined with corrective farriery
  • Do surgery if no improvement in 4-8wks
  • Cut ligament or tendon
50
Q

What is the surgical treatment for a flexural limb deformity with the MCP joint?

A

•Transect structures involved – can be done standing under sedation

–Accessory Ligament of SDFT – will help the most

–Accessory ligament of DDFT

•Salvage

–SDFT tenotomy

–Suspensory ligament desmotomy

–Don’t do these a lot and try to discourage these salvage procedures often – they are not standard fashion

51
Q

What is the prognosis for a congenital flexural limb deformity?

A
  • Good is improvement within first 7-14 days, if not – prognosis decreases with time
  • Depends on extent of correction achieved
  • Transection of ligaments/ tendons likely to compromise future athletic potential
52
Q

What is the prognosis for an acquired flexural limb deformity?

A
  • Depends how far you need to go with surgical procedures you need to go to fix it
  • DIP

–Good if mild and responds to treatment

–ALDDFT desmotomy

•Reasonable for athletic potential

–DDFT tenotomy

  • Salvage procedure
  • MCP

–Worse than DIP

–Depends on response to tx and aggressiveness of surgical intervention

53
Q

What is digital hyperextension also known as?

A

Hyperlaxity

54
Q

What are the clinical sings of digital hyperextension?

A
  • Common in neonates (usually mild)
  • Toe off ground in first couple of days after both, causing:
  • Hyperextension of MCP/MTP joints
55
Q

What ais the pathogenesis of digital hyperextension?

A

Caused by flaccid/ weak flexor muscles – not used a lot yet

56
Q
A
57
Q

What is the treatment for digital hyperextension?

A
  • Usually self-corrects within a few days
  • If severe may cause trauma to palmar/plantar aspect of phalanges
    • Restrict exercise if trauma
    • Protect from trauma
      • NOT heavy bandaging
  • Heel extensions if not self-correcting or very severe – sedate foal. Vet or farrier can do this
58
Q

Patient

  • Species: Equine
  • Age: Neonate
  • Sex: Unknown
  • Body condition: Unable to determine

Imaging modality

  • Radiography

Image orientation

  • Dorsopalmar view of carpus, lateral to right
    1. Comment on the positioning, centering, collimation, exposure, labelling, artefacts, good enough quality?
A

•Positioning

–Good

•Centring

–Good

•Collimation

–Good

•Exposure

–Good; periphery is black, which suggests that exposure and development are adequate; bones have reasonable contrast; ossified and non-ossified skeletal components can be identified easily; soft tissues not visible but not required for diagnosis of condition suspected (note that this image has probably been manipulated in software)

•Labelling

–Absent

•Are images free of faults/artefacts?

–Yes

•Are the images of good enough quality to use for diagnosis?

– Yes

59
Q

Patient

  • Species: Equine
  • Age: Neonate
  • Sex: Unknown
  • Body condition: Unable to determine

Imaging modality

  • Radiography

Image orientation

  • Dorsopalmar view of carpus, lateral to right
    1. Comment on soft tissues, radius, lateral styloid procee, carpal bones, third metacarpal bone and presence or absence of limb deviation in frontal plane
A

•Soft tissues

–Not visible

•Radius

–Margins of distal epiphysis more rounded than in normal foal at term

•Lateral styloid process

–Rounded margins; has not fused with distal radial epiphysis (as is normal up to one year of age)

•Carpal bones

–Rounded contours; incomplete ossification (severe)

•Third metacarpal bone

–Proximal physis fused (as is normal at birth)

–Proximal margin more rounded than in normal foal at term

•Presence or absence of limb deviation in frontal plane

–Carpal valgus

60
Q

Patient

  • Species: Equine
  • Age: Neonate
  • Sex: Unknown
  • Body condition: Unable to determine

Imaging modality

  • Radiography

Image orientation

  • Dorsopalmar view of carpus, lateral to right
    1. Common on the conclusion (what does the radiograph show), the diagnosis and DD and anyt further investigations or recommendations
A

Conclusions

•This radiograph shows:

–Incomplete ossification of cuboidal bones of carpus

–Carpal valgus

Diagnosis/differential diagnosis:

  • Incomplete carpal ossification
  • Angular limb deformity (carpal valgus)

Further investigations/recommendations

  • Radiograph contralateral carpus (dorsopalmar view) on a long cassette
  • From radiographs, measure angle of deviation in frontal plane of both carpi; determine anatomical origin of deformity
  • Radiograph both tarsi (lateromedial views)

Equine Final Year (102 decks)

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