DOD 1 Flashcards
Why is prompt evaluation essential? (3)
–Deformation of cartilage
–Adaptation (modelling) of bone rapidly in response to (abnormal) biomechanical forces
–Failure to treat quickly may adversely affect adult conformation and athletic potential
Give 2 reasons lameness treatment is challenging in foals (3)
–Thin skin → rapid development of pressure sores under bandages/casts (irritation)
–Small hooves, thin wall → difficult to attach shoes
–Manipulation/physical therapy may be resented
Whats the problem here?
There is very little bone
Joint: carpus
Problem with the ossification
What is the development and re-modeeling of bone influenced by?
Mechanical forces
Name an effect of inappropriate mechanical forces? (2)
–Initiate pathology
–Reduce effectiveness of treatments
How can angular limb defority result from foal lameness?
Foal is uncomfortable weight bearing on one limb they may become dependant on the contra lateral limb = angular limb deformity
What are the 4 types of juvenile osteochondral conditions?
–Osteochondrosis/-itis /-dissecans
–Subchondral cystic lesions
–Physeal dysplasia
–Cuboidal bone collapse
Name 4 developmental orthopaedic diseases
- Juvenile osteochondral conditions
- Angular limb deformity
- Flexural limb deformity
- Cervical vertebral malformation (‘wobbler syndrome’)
What is the difference between angular limb deformities and flexural limb deormity?
ALD is a problem with the angle of the limb and how bone grows, a FLD is related to soft tissues and contractions of flexor tendons
What is the dissecans form of OCD?
Bone fragments detached
Name 3 things contributing to DOD (5)
–Rapid growth (e.g. soft tissue doesn’t grow as fast as the bone= flexural limb deformity)
–Overnutrition (maternal and foetal)
–Unbalanced nutrition
–Genetic predisposition (polygenic)
–Biomechanical forces – act on the normal joint but will also act on the abnormal joint e.g. angular limb deformity
With the failure of endochrondral ossification, what is the cartilage necrosis assocaited with?
Necrotic cartilage canal blood vessels
What does this show?
Osteochondrosis
Cartilage necrosis forms the OCD. Result of necrotic cartilage blood canals
What is this?
Osteochondritis
What is the realtionship between orthopaedic disease and exercise? (2)
Increased risk with:
- Box rest
- Irregular exercise
What is the relationship between diet and orthopaedic disease (4)
Increased risk with:
–Excessive digestible energy
–Excessive dietary phosphorus
–Copper deficiency or low Cu:Zn ratio (lysyl oxidase)
–Concentrate during gestation
What is seen radiographically with thickened cartilage?
Radiographically evident as defect in subchondral bone contour
What may happen with the fragment in Intra-articular cartilage fragments (OCD)?
Fragment may detached and May ossify after separation
What does subchondral bone cysts normally follow on from? (2)
Following on from ischaemic chondronecrosis lesion
Also secondary to trauma
Label
- Thickened cartilage
- Intra-articular cartilage fragments (OCD)
- Subchondral bone cysts
What are the 3 main predilection sites of orthopaedic disease in horses?
- Femoropatellar joint (stifle)
- Tarsocrural (tibiotarsal)
- ‘Fetlock’ joint
Femoropatellar joint (stifle):
A) What is the most common OCD place?
B) What are the 3 places it occurs?
C) Where is the most common site for the cystic form?
A) The lateral trochlear ridge
B) Lateral and medial femoral trochlear ridges, Lateral femoral condyle of the distal femur is the predilection site facet of patella
C) Medial
What are the 3 sites of OCD in the Tarsocrural (tibiotarsal) joint (tarsus)?
–Distal intermediate ridge of tibia
–Medial malleolus of tibia
–Lateral & medial trochlear ridges of talus
What are the 2 OCD sites in the fetlock joint?
–Midsagittal ridge of Mc/Mt III
–Condyles of Mc/Mt III
What are the clinical signs of Osteochondrosis/ -itis/ OCD? (3)
–Joint effusion
–Lameness (varying degrees)
–Onset may be associated with exercise/trauma
Where in the horse is OCD less likely to cause OCD?
Tarsus
What are the clinical signs of a subchondral bone cyst? (2)
–Lameness (often subtle)
–± Joint effusion
Which trochler ridge is bigger?
Medial
What are the radiographic signs of orthopaedic disease that can be seen? (5)
•Subchondral bone
–Flattening
–Irregular contour
–Lucencies
- Intra-articular fragments
- Subchondral bone cyst
What is the problem here?
Subchondral bone cyst
Common here in a young bone;
Fetlock
What is the problem here?
OCD
What can be see here?
This is normal:
Patella
Sits between the trochlear ridges
NAme 3 treatment influencing factors (4)
–Age of horse
–Site and severity of lesions
–Proposed career
–Financial constraints
When can hock lesions disappear?
Up to the age of 5 months
How long can it take for stifle OCD lesions to disappear alone?
8-9 months
What are the treatment options for OCD? (6)
Conservative
–Box/small paddock rest 60-90d
–Correct dietary imbalances
–Reduce dietary energy intake
Surgical
–Removal of fragments and debridement of abnormal tissue –
–Usually wait until they are 15-18 months before we do this
–Exception – so much effusion the capsule will stretch and if we leave it for months it would result in deformation
What are the treatment options for a cyst?(5)
Conservative
–Rest
–± NSAIDS or i.a. corticosteroids
- Intra-lesional corticosteroid injection
- Arthroscopic debridement – this should NOT be done!!! Increase the risk of meniscus injury
- Intra-lesional implantation with allogenic chondrocytes & IGF-1
What does the prognosis of orthopaedic disease depend on? (4)
–Age
–Site and severity
–Treatment option
–Intensity of athletic career
What is the prognosis of orthopaedic disease?
Excellent (able to fulfil full athletic potential) to poor (persistent lameness/ osteoarthritis)
Name 2 ways of preventing orthopaedic disease (3)
- Breeding
- Not from affected animals
- Not from animals whose progeny show a high incidence
- Balanced and adequate (not excessive) plane of nutrition in pregnant mares, foals and weanlings
- Keep foals on pasture (exercise) during growing period
What is physeal dysplasia?
Enlargement of physis ± metaphysis during growth period
Name 3 common sites of physeal dysplaia (4)
- Distal metacarpus/metatarsus (3–6 mo)
- Proximal first phalanx (3–6 mo)
- Distal radius (8–20 mo)
- Distal tibia (8–20 mo)
What is the pathogensis of physeal dysplasia?
Mis-match between metaphyseal bone and applied load
- Osteochondral collapse
1. Normal load on abnormal bone - Defective ossification/ maturation (infection, nutritional deficiency/ imbalance, rapid growth)
- Under-stimulation of bone-forming process (exercise restriction)
- Abnormal load on normal bone
* Trauma, poor conformation, abrupt increase in exercise
What are the clinical signs of physeal dysplasia? (4)
- Firm, warm painful enlargement of physeal region
- Usually bilateral/ quadrilateral
- ± Lameness/ stilted gait
- Frequently associated with rapid growth and high plane of nutrition
- Mare’s milk
- Grazing
What is this?
Physeal dysplasia
What are the radiographic sign of physeal dysplasia? (4)
Focal widening of growth cartilage
- Inflammation -> slowed ossification -> cartilage accumulation
Sclerosis of metaphysis/ loss of trabecular pattern
Callus/ woven bone production rather than trabecular bone
‘Flaring’ of physis
Periosteal new bone
How can we treat physeal dysplasia? (5)
- Mild, non-painful => monitor
- Restrict exercise
- NSAIDs if painful (CAVE: kidney function)
- Balance diet and reduce energy intake
- Manage any associated angular limb deformity
–Watch the contra lateral limb to prevent this occurring
What is the prognosis of physeal dysplasia?
Excellent, usually resolves with appropriate management
What may physeal dysplasia lead to? (2)
–ALD via bony bridging of physis on affected side
–Flexural deformity 2y to lameness and reduced weight bearing
How can you prevent physeal dysplasia? (4)
- Balanced diet
- Do not overfeed
- Do not allow sudden or inappropriate increase in exercise
- Treat any lameness or musculoskeletal deformity promptly to avoid 2y physeal dysplasia
Compelte a technical assessment
Positioning
–Good
Centring
–Proximal to femorotibial joint
–Adequate for visualisation of femoral trochlear ridges
Collimation
–Over-collimated; caudal aspects of femur and tibia, and proximal aspect of patella not included in radiograph (may be due to cropping in software)
Exposure
–Periphery is black but bones lack contrast; it is likely that this image has been manipulated in software, hence difficult to comment on original exposure factors
Labelling
–Absent (may be due to cropping)
Are images free of faults/artefacts?
–Yes
Are the images of good enough quality to use for diagnosis?
–Just about; image can be used for diagnosis of primary lesion identified, but cropping and manipulation limits evaluation of other areas of joint
Complete an image assessment
Soft tissues
–Distension of femoropatellar joint capsule
Patella
–Remodelling of apex
Femur
–Irregular contour of subchondral bone of lateral trochlear ridge, primarily affecting middle third of ridge
–Numerous radiopaque, rounded fragments adjacent to lateral trochlear ridge and within femoropatellar joint
Tibia
–No abnormalities detected
What are the conlusions of this radiograph?
–Femoropatellar effusion
–Multiple radiopaque, rounded fragments adjacent to lateral trochlear ridge of femur, and within femoropatellar joint
–Degenerative joint disease
What is the diagnosis? Or differentials?
- These radiographic findings are typical of osteochondrosis/osteochondritis dissecans (OCD)
- Remodelling of apex of patella is likely to be a secondary change, indicative of degenerative joint disease
What would further investigations/recommendations be?
- Obtain another radiograph (caudal 60° lateral-craniomedial oblique) which includes the caudal aspects of the tibia and femur, and the proximal aspect of the patella
- As this horse presumably has clinical signs relating lameness to this stifle joint, a caudocranial view is indicated
- Radiograph the contralateral stifle (osteochondrosis is frequently bilateral)
