Common Orthopedic Diseases Flashcards
Developmental Orthopedic Disease
Developmental Osteochondrosis
- Osteochondritis dissecans (“OCD”)
- Subchondral bone cysts
- Physeal dysplasia
<><>
- angular limb deformities
<><>
- flexural deformities
<><>
- cervical vertebral malformation
developmental osteochondrosis terminology:
- Osteochondrosis
- Osteochondritis dissecans (“OCD”)
- Osteochondral fragment
§ Osteochondrosis = a disorder of bone and cartilage
(developmental or traumatic/degenerative).
<><>
§ Osteochondritis dissecans (“OCD”) = a flap-like lesion of abnormal articular cartilage or cartilage + bone.
<><>
§ Osteochondral fragment = a detached fragment of articular cartilage and bone (traumatic or developmental).
Developmental Osteochondrosis
Pathophysiology:
A failure of normal endochondral ossification.
Ø Physeal or articular-epiphyseal complex.
Review – how does bone grow?:
- Primary Center of ossification = diaphysis
- Secondary center of ossification = epiphysis (each end)
- Inbetween = epiphyseal plate – continues to form cartilage that is replaced with bone
- Once bone from primary & secondary center meets, only physeal scar left
in normal bone formation, after ossification of diaphysis and epiphyses, where does hyaline cartilage remain?
only in the epiphyseal plates and articular cartilages
Developmental Osteochondrosis - pathogenesis
- Abnormal chondrocyte differentiation.
- Synthesis of defective extracellular matrix.
- Persistence of chondrocytes in mid-to-late hypertrophic zone.
- Failure of vascular in-growth and ossification.
- Thickening and retention of the hypertrophic zone of the growth cartilage.
what are the ‘zones’ of development, as bone replaces hyaline cartilage in normal development?
- Resting zone = normal hyaline cartilage
- Proliferative zone = chondrocytes > rapid proliferate = cell columns
- Zone of maturation/hypertrophy – big cells & secrete ALK Phos
- Zone of calcification/ossification – chondrocytes die & osteoblasts invade
Developmental Osteochondrosis
2 Basic Manifestations when articular-epiphyseal complex affected:
- Osteochondritis dissecans (more common?)
- Subchondral bone cysts
Osteochondritis dissecans - what is this
- Flaps or fragments of cartilage or cartilage & bone = OCD lesions.
- Shear forces may favor formation of OCD lesions.
- Gliding surfaces.
Subchondral bone cysts - what are these?
- In-folding of defective cartilage = formation of SBC’s.
- Compressive forces may favor SBC formation.
- Central weight-bearing regions.
Developmental Osteochondrosis
Etiology:
Complex, multifactorial and incompletely understood.
- Growth Rate - High energy diets and rapid growth are associated with OC in some species.
- Dietary Factors - High carbohydrate load. - Low Cu++ (or high Zn++).
- Genetics - High heritability of OC indicated in some studies. - Specific genetic defect not identified.
- Trauma - Not a primary factor, but plays a role in both the pathogenesis of some lesions, and in the precipitation of clinical signs.
OCD & Subchondral Bone Cysts
General Concepts:
- who gets them?
- clinical signs?
- Dx?
- significance?
- Younger horses → Foals, weanlings, yearlings, 2-year-olds.
- Clinical Signs → joint effusion and lameness.
> Joints are not hot and flexion is tolerated.
> Lameness ranges from subtle-to-moderate (rarely severe). - Diagnostic analgesia is rarely necessary.
- Radiographs are the primary diagnostic modality.
- Not all OCD & SBC lesions cause lameness or effusion.
> Often seen as an incidental finding in older horses.
Developmental OC of the Fetlock
Lesions
- OC fragments of proximal palmar/plantar P-1.
- OCD of distal, dorsal MC-3 & MT-3 (sagihal ridge).
- SBC’s of distal MC-3 & MT-3.
- OC fragments of proximal, dorsal P-1.
OC Fragments of Palmar/Plantar P-1
- 4 Types of Palmar/Plantar Fetlock Fragments:
1st Phalanx
- Type 1 - subchondral flattening or separate fragments abaxial to sagittal groove. (intra-articular)
- Type 2 - fragments on the abaxial aspect of the palmar/plantar process. (extra-articular)
<><>
Proximal Sesamoid
- Type 3 - fragments off the distal aspect of the sesamoid bones.
- Type 4 - fragments within the distal sesamoidean ligaments.
OC Fragments of Palmar/Plantar P-1
- Clinical Signs
- treatment
- prognosis
- Minimal joint effusion (vs. other “OCD” lesions)
- Lameness, if present, typically only affects the horse at high speed.
> rarely have clinical signs otherwise
<><><><>
Treatment: - arthoscopic debridement
> Either pre-sale or prior to training.
> When associated with lameness (otherwise dont go in, unless you know where the fragment is, perhaps…)
<><><><>
Prognosis - Good-to-excellent for most lesions.
OCD of Distal, Dorsal MC/MT-3
- Sagittal Ridge Lesions divided into 3 Types:
- Type 1 - subchondral flattening.
- Type 2 - flattening in addition to a bony fragment.
- Type 3 - loose osseous body within the dorsal joint.
OCD of Distal, Dorsal MC/MT-3
- clinical signs
- treatment, based on type
- prognosis
Clinical Signs
- Joint effusion is typically the initial clinical sign.
- Lameness tends to be mild.
<><>
Treatment
- Arthroscopic debridement for Types 2 & 3.
- Rest is appropriate treatment for Type 1 lesions.
<><>
Prognosis
- Generally very good (if minimal associated DJD).
Subchondral Cysts of MC/MT-3
- how common
- treatment
- prognosis
- Less common than the other lesions in the fetlock joints.
<><>
Treatment options: - Arthroscopic debridement.
- Intralesional corticosteroid injection.
- Intra-articular medication and rest.
<><>
-The prognosis for hard athletic use is guarded.
OCD of the Tarsus
- lesions – Tarsocrural Joint tibiotarsal joint).
- Cranial, distal, intermediate ridge of the tibia (DIRT).
- Medial malleolus of the tibia.
- Lateral trochlear ridge of the talus.
- Medial trochlear ridge of the talus.
OCD of the Tarsus
Clinical Signs
treatment
prognosis
Clinical Signs
- Joint effusion is #1.
- Lameness typically does not develop
until horses are in athletic training.
<><>
Treatment
- Arthroscopic debridement.
<><>
Prognosis
- Typically good, if not excellent.
- Prognosis decreases with more extensive disease.
- Also less favorable when degenerative changes have developed.
Osteochondrosis of the Stifle
Lesions
- OCD - lateral trochlear ridge of the femur.
- SBC - medial condyle of the femur > always has compressive forces on it
Osteochondrosis of the Stifle
Clinical Signs for OCD lesions:
for SBC lesions:
OCD (lateral trochlear ridge of the femur)
- Femoropatellar effusion is a consistent sign.
- Lameness is typically minimal-to-moderate.
<><><>
SBC (medial condyle of the femur)
- Effusion less common with SBC lesions.
- Lameness ranges from mild-to-severe.
Osteochondrosis of the Stifle
Treatment for OCD lesions:
for SBC lesions:
convelescence?
OCD lesions
- Arthroscopic debridement.
- (Selected cases will improve with long-term rest.)
<><>
SBC’s
- Arthroscopic debridement > only if cyst has wide opening
- Intralesional corticosteroid injection.
- Intra-articular medication and rest.
<><>
- 6 -12 months convalescence is often necessary.
Osteochondrosis of the Stifle
Prognosis
Depends on severity of lesions and clinical signs.
- Guarded-to-good for OCD lesions.
- Less favourable for SBC’s, in general.
Osteochondrosis of the Shoulder
Lesions
- 25% humeral head, 25% glenoid, 50% both sites.
- OCD lesions on the humeral head.
- SBC’s in the glenoid.
Osteochondrosis of the Shoulder
clinical signs
- Most horses first exhibit lameness as weanlings or yearlings.
- Lameness ranges from mild-to-severe.
Osteochondrosis of the Shoulder
Treatment, prognosis
- Arthroscopic debridement.
- Rest, ± IA medication.
<><>
Prognosis - Guarded at best (often poor for hard athletic use).
Physeal Dysplasia
a.k.a. “Physitis” or “Epiphysitis”
- pathogenesis, risk factors
Pathogenesis: some similarities with articular osteochondrosis.
- Failure of endochondral ossification → widening of the growth plate (physeal complex)
<><>
Similar risk factors:
- Nutritional/metabolic (mineral imbalances, feeds with high glycemic index).
- Genetic predisposition.
- High growth-rate.
- Trauma.
physeal dysplasia common locations
- Distal 3rd metacarpal/metatarsal physis.
- distal radial physis
- distal tibial physis
- usually bilateral (or quadrilateral in MC/MT-3)
