Podcast
Questions and Answers
Which type of tarsus is considered good for athletic performance?
Which type of tarsus is considered good for athletic performance?
Angular limb deformity can only occur in the carpus.
Angular limb deformity can only occur in the carpus.
False
What is the most common cause of angular limb deformity due to asynchronous growth?
What is the most common cause of angular limb deformity due to asynchronous growth?
Asynchronous metaphyseal growth
Medial deviation of a limb is referred to as __________.
Medial deviation of a limb is referred to as __________.
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Match the following clinical signs with their descriptions:
Match the following clinical signs with their descriptions:
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Which of the following is NOT a common developmental orthopaedic disease in horses?
Which of the following is NOT a common developmental orthopaedic disease in horses?
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Incomplete ossification of cuboidal bones can occur in foals due to being born prematurely.
Incomplete ossification of cuboidal bones can occur in foals due to being born prematurely.
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What are the primary clinical signs of cuboidal bone hypoplasia?
What are the primary clinical signs of cuboidal bone hypoplasia?
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Treatment for severe cases of cuboidal bone hypoplasia may involve using a _______ for 10-14 days.
Treatment for severe cases of cuboidal bone hypoplasia may involve using a _______ for 10-14 days.
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Match the type of cuboidal bone compression with its description:
Match the type of cuboidal bone compression with its description:
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What is the primary ingredient in Cosequin?
What is the primary ingredient in Cosequin?
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Cold application is not effective during the inflammatory phase of treatment.
Cold application is not effective during the inflammatory phase of treatment.
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Name one method of physical therapy that helps to prevent capsular fibrosis.
Name one method of physical therapy that helps to prevent capsular fibrosis.
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Acupuncture is considered a form of __________ therapy.
Acupuncture is considered a form of __________ therapy.
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Match the following physical therapies with their uses:
Match the following physical therapies with their uses:
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What is the most common area for osteochondritis dissecans (OCD) to occur?
What is the most common area for osteochondritis dissecans (OCD) to occur?
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Subchondral bone cysts (SBC) always disrupt the articular surface.
Subchondral bone cysts (SBC) always disrupt the articular surface.
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List one genetic factor that can predispose horses to osteochondritis dissecans (OCD).
List one genetic factor that can predispose horses to osteochondritis dissecans (OCD).
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In OCD, _____ is released during the inflammatory response, leading to pain.
In OCD, _____ is released during the inflammatory response, leading to pain.
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Match the clinical signs with the related conditions:
Match the clinical signs with the related conditions:
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Which of the following is NOT a proposed factor in the aetiopathogenesis of OCD/SBC?
Which of the following is NOT a proposed factor in the aetiopathogenesis of OCD/SBC?
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Osteochondrosis can be diagnosed with radiography alone.
Osteochondrosis can be diagnosed with radiography alone.
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What percentage of racehorses typically return to performance after early treatment for OCD?
What percentage of racehorses typically return to performance after early treatment for OCD?
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Subchondral bone cysts may communicate with the _____ space.
Subchondral bone cysts may communicate with the _____ space.
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Which imaging technique is deemed the treatment of choice for OCD?
Which imaging technique is deemed the treatment of choice for OCD?
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What percentage of draught horses typically has synovial effusion resolve over time?
What percentage of draught horses typically has synovial effusion resolve over time?
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All horses are equally prone to developing OCD, regardless of size or breed.
All horses are equally prone to developing OCD, regardless of size or breed.
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Femoropatellar OCD primarily affects older horses.
Femoropatellar OCD primarily affects older horses.
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Name one condition that can induce subchondral bone cysts.
Name one condition that can induce subchondral bone cysts.
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High phosphorus diets can be _____ times the National Research Council (NRC) recommendation.
High phosphorus diets can be _____ times the National Research Council (NRC) recommendation.
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What is the most common site for subchondral bone cysts in equines?
What is the most common site for subchondral bone cysts in equines?
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Match the following locations to their frequency of occurrence in OCD:
Match the following locations to their frequency of occurrence in OCD:
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The most consistent clinical sign of femoropatellar joint issues is ________.
The most consistent clinical sign of femoropatellar joint issues is ________.
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What is the prognosis for a lesion that is less than 2 cm long?
What is the prognosis for a lesion that is less than 2 cm long?
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Concurrent lesions in multiple areas of the joint predict a better prognosis.
Concurrent lesions in multiple areas of the joint predict a better prognosis.
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Which horse breeds are most commonly affected by femorotibial OCD?
Which horse breeds are most commonly affected by femorotibial OCD?
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If there are radiographic lesions, some intervention is recommended, such as injecting a ________ into the joint.
If there are radiographic lesions, some intervention is recommended, such as injecting a ________ into the joint.
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What is the age range often seen for horses with subchondral bone cysts?
What is the age range often seen for horses with subchondral bone cysts?
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Match the type of intervention with its appropriate indication:
Match the type of intervention with its appropriate indication:
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How many femorotibial joints and femoropatellar joints generally communicate with each other?
How many femorotibial joints and femoropatellar joints generally communicate with each other?
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The majority of horses presenting with SBC are typically older than 3 years.
The majority of horses presenting with SBC are typically older than 3 years.
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Which view is most rewarding for radiography in diagnosing SBC?
Which view is most rewarding for radiography in diagnosing SBC?
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The primary clinical complaint from owners of horses with SBC is ________.
The primary clinical complaint from owners of horses with SBC is ________.
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What percentage of foals diagnosed with femoropatellar OCD may show an absence of ossification of the lateral trochlear ridge?
What percentage of foals diagnosed with femoropatellar OCD may show an absence of ossification of the lateral trochlear ridge?
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What is the success rate of a transcortical screw technique?
What is the success rate of a transcortical screw technique?
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Osteoarthritis and traumatic joint disease are the most common equine health issues.
Osteoarthritis and traumatic joint disease are the most common equine health issues.
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Name one type of joint class based on anatomy.
Name one type of joint class based on anatomy.
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The fluid that nourishes and lubricates the joint is called __________.
The fluid that nourishes and lubricates the joint is called __________.
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Match the type of arthritis with its description:
Match the type of arthritis with its description:
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Which of the following is NOT a manifestation of joint trauma?
Which of the following is NOT a manifestation of joint trauma?
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Hyaluronan is a key component of articular cartilage, providing resistance to shear and tension.
Hyaluronan is a key component of articular cartilage, providing resistance to shear and tension.
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What is the typical cell count for normal synovial fluid?
What is the typical cell count for normal synovial fluid?
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Type A synovial cells are primarily __________.
Type A synovial cells are primarily __________.
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Match the following substances with their function related to joint health:
Match the following substances with their function related to joint health:
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What condition can develop after a trauma to a joint?
What condition can develop after a trauma to a joint?
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Meniscal tears are associated with traumatic arthritis.
Meniscal tears are associated with traumatic arthritis.
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What are two common clinical signs of joint injury?
What are two common clinical signs of joint injury?
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Chondroitin 4- & 6-sulfates are examples of __________ found in joint tissue.
Chondroitin 4- & 6-sulfates are examples of __________ found in joint tissue.
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What is a common result of chronic stress-related subchondral bone damage in the fetlock joint?
What is a common result of chronic stress-related subchondral bone damage in the fetlock joint?
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Osteoarthritis typically causes progressive deterioration of articular cartilage and leads to improved joint function over time.
Osteoarthritis typically causes progressive deterioration of articular cartilage and leads to improved joint function over time.
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List one type of IA fracture.
List one type of IA fracture.
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The most potent class of drugs used for osteoarthritis are __________.
The most potent class of drugs used for osteoarthritis are __________.
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Match the following treatments with their usage:
Match the following treatments with their usage:
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What is a primary clinical sign of osteoarthritis?
What is a primary clinical sign of osteoarthritis?
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Hyaline cartilage is easily regenerated after injury.
Hyaline cartilage is easily regenerated after injury.
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What imaging method is used to evaluate cartilage and soft tissue?
What imaging method is used to evaluate cartilage and soft tissue?
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Commonly affected bones in IA fractures include the radial carpal bone and the __________ carpal bone.
Commonly affected bones in IA fractures include the radial carpal bone and the __________ carpal bone.
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Which factor does NOT contribute to osteoarthritis?
Which factor does NOT contribute to osteoarthritis?
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Capsulitis and synovitis can initiate the early stages of osteoarthritis.
Capsulitis and synovitis can initiate the early stages of osteoarthritis.
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What is the goal of treatment for type III osteoarthritis?
What is the goal of treatment for type III osteoarthritis?
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Arthroscopy can be used to debride loose fragments and perform __________.
Arthroscopy can be used to debride loose fragments and perform __________.
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Match the following diagnostic methods with what they reveal:
Match the following diagnostic methods with what they reveal:
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What is the ideal age for performing surgery on distal MCIII/MTIII deviations?
What is the ideal age for performing surgery on distal MCIII/MTIII deviations?
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The prognosis for mild/moderate cases of angular limb deformity is generally poor.
The prognosis for mild/moderate cases of angular limb deformity is generally poor.
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What is epiphysitis?
What is epiphysitis?
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Surgical intervention is indicated for ___________ deviations.
Surgical intervention is indicated for ___________ deviations.
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Match the following surgical procedures with their descriptions:
Match the following surgical procedures with their descriptions:
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What dietary changes may help prevent epiphysitis in rapidly growing foals?
What dietary changes may help prevent epiphysitis in rapidly growing foals?
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Flexural deformities are exclusively congenital and cannot be acquired.
Flexural deformities are exclusively congenital and cannot be acquired.
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What is a primary clinical sign of epiphysitis?
What is a primary clinical sign of epiphysitis?
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NSAIDs are used for __________ pain management in cases of skeletal deformity.
NSAIDs are used for __________ pain management in cases of skeletal deformity.
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Match the following clinical signs with the appropriate conditions:
Match the following clinical signs with the appropriate conditions:
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What is a common treatment for mild flexural deformities?
What is a common treatment for mild flexural deformities?
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Increasing nutritional intake is recommended for young horses with epiphysitis.
Increasing nutritional intake is recommended for young horses with epiphysitis.
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What major risk is associated with severe angular limb deformities if not corrected early?
What major risk is associated with severe angular limb deformities if not corrected early?
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A common result of osteochondrosis is the retention of __________ in the growth plates.
A common result of osteochondrosis is the retention of __________ in the growth plates.
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Match the following joint conditions with their associated age range:
Match the following joint conditions with their associated age range:
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Study Notes
Developmental Orthopaedic Disease: Lameness in Young Horses
-
Common Developmental Orthopaedic Disease (DOD) in Horses:
- Cuboidal bone malformation
- Acquired angular limb deformity (ALD)
- Epiphysitis/physitis/physeal dysplasia
- Flexural limb deformities
- Osteochondrosis (OCD; SBC’s)
- Cervical vertebral malformation
- Juvenile arthritis
Cuboidal Bone Hypoplasia
- Incomplete ossification of the cuboidal bones of the carpus or tarsus (or both)
- Most cuboidal bone ossification occurs in the last 2-3 weeks of gestation, except in:
- Premature (< 320 days) or dysmature foals
- Congenital/developmental anomalies
- Affected foals may also have decreased muscle tone and flexor tendon laxity.
Clinical Signs of Cuboidal Bone Hypoplasia
- Angular deviation of limb (valgus, vertical?)
- Excessive laxity – especially carpi & tarsi
- Tarsal or carpal bone wedging and/or collapse (confirmed on radiographs)
Diagnosis of Cuboidal Bone Hypoplasia
- Signalment & Physical Examination
- Radiography (Wide joint spaces, small round cuboidal bones)
Grades of Cuboidal Bone Hypoplasia (Tarsus)
- Type I: < 30% compression
- Type II: > 30% compression; fragmentation
Treatment of Cuboidal Bone Hypoplasia
- Minimize compressive forces and further injuries
- Confinement (most important)
- Severe cases: tube splints or tube casts for 10-14 days (difficult to manage in fast-growing foals)
- Monitor ossification (re-radiograph at 2-weekly intervals)
Prognosis of Cuboidal Bone Hypoplasia
- Carpus:
- Better with increasing grade (i.e. ossification)
- Carpal bone collapse = Poor
- Tarsus:
- Type I: good for athletic performance
- Type II: poor for athletic performance
Angular Limb Deformity (ALD)
- Limb deviation from the long axis in the frontal plane
- Medial deviation = Varus
- Lateral deviation = Valgus
- May be accompanied by digital rotation
- Occurs most commonly in the carpus, fetlock, and tarsus (other joints rarely)
Aetiology of ALD
- Asynchronous metaphyseal growth is the most common cause
- Other differentials: Joint laxity, Cuboidal malformation, Physeal trauma, Poor foot trimming, In-utero mal-positioning
Clinical Signs of ALD
- Angular deviation (examine standing and at walk from different viewpoints)
- Differential diagnosis = Joint laxity (Cuboidal bone malformation; windswept foals, ligament flaccidity)
- Differential diagnosis = Joint swelling (Physeal trauma; fracture; sepsis)
Diagnosis of ALD
- Physical findings:
- Visual presentation
- Identify the center of rotation
- Measure angles to assess the degree of abnormality (goniometry)
- Palpation findings: laxity, pain, etc.
- Trim & balance feet; re-examine on flat surface
- Radiography:
- +/- Cuboidal bone abnormalities
- Identify center of rotation
- Goniometry on radiographs
Treatment of ALD
- Age:
- Distal radial/tibial physes < 6 months (surgery 6 weeks - 12 months)
- Distal MCIII/MTIII < 3 months (surgery as soon as noticed)
- Degree of deviation:
- Mild-moderate carpal deviation in foals < 4 months:
- Small paddock/stall confinement
- Trim feet (outside of feet for valgus)
- Dorsomedial/dorsolateral feet extensions
- Frequent reassessment vital (Weekly)
- Especially for fetlock (short window of growth) Surgery as soon as possible on fetlocks.
- Mild-moderate carpal deviation in foals < 4 months:
Surgical Procedures for ALD
- Transphyseal hemi-circumferential periosteal elevation (stripping):
- Stimulates growth on the side of the growth plate that was growing too slowly
- Always with foot trimming & confinement
- Carpus by 4-5 months (up to 12)
- Fetlock by 2 months
- Transphyseal bridging:
- For moderate to severe (> 15°) deviations
- Impairment of growth in the convex side of the limb
- Screws & wire or transphyseal screw (most common)
- 2-hole plate or staple
- Wedge or dome osteotomy for severe cases
- Resection of physis (older weanlings):
- Carpus only
- Carpus by 4-5 months
- Fetlock by 3 months
Complications of ALD Surgery
- Incision infection
- Implant breakage
- Excessive periosteal reaction
Prognosis of ALD
- Mild/moderate cases are good
- Fetlock varus more likely to result in fetlock/pastern OA
- Severe ALD more likely to lead to OA if not corrected early
- Generally perform at the same level as peers if treated
Epiphysitis/Physitis
- Abnormal thickening of the physis/epiphysis
- Multifactorial in origin (single/bilateral, multiple joints)
Aetiology of Epiphysitis/Physitis
- Physeal injury/excess compression during active growing phase
- Nutritional:
- Low dietary Cu & Zn
- Limb overloading may lead to contralateral limb physitis
Signalment of Epiphysitis/Physitis
- Foals +/- ALD
- Fetlock: 3-6+ months
- Rapidly growing wealing/yearlings – often large bodied for age:
- Distal radius: 8 months to 2 years
- Distal tibia: less commonly observed
- Overfed for rapid growth
Clinical Signs of Epiphysitis/Physitis
- Firm, warm, enlargement of physis (most common on the medial side)
- Usually occurs in the distal radius, tibia, MC/MT III
- Usually painful on deep palpation
- ALD/flexor tendon contracture
- Lameness (can range from stiffness to reluctance to stand)
- Distal radius or tibia; not usually both
- If distal MC/MT III; usually all 4 involved
- Concurrent ALD or flexor tendon contracture in severe or chronic cases
Diagnosis of Epiphysitis/Physitis
- Signalment & nutritional history
- Physical examination findings:
- Palpation of all long bone physes
- Gait evaluation
- Radiographs:
- Metaphyseal flaring
- Asymmetry:
- Metaphysis
- Cortical thickness
- Widening of the physis
- Wedging of the epiphysis
- Partial physeal closure/bridging
Treatment of Epiphysitis/Physitis
- Reduce growth rate and/or body mass (only works on young, still growing horses)
- Evaluate feed:
- Reduce energy intake
- Formulated diet
- Good quality grass hay; reduce/replace lucerne
- Reduce milk intake in nursing foals
- Early weaning
- NSAID—Phenylbutazone 2-3 weeks @ lower doses
- Stall confinement or minimize activity to prevent further physeal trauma (2 weeks to 2 months)
- Corrective hoof trimming
- Treat ALD or flexural deformities if present and young enough
Prognosis of Epiphysitis/Physitis
- Mild cases are often self-limiting; may resolve with skeletal maturity
- Good prognosis for athletic activity
- Poorer for athletic career if conformation permanently affected
- Greater risk of injury; Severe carpal varus; Bench knee
Flexural Limb Deformities
- Inability to extend limb fully due to difference between bone length vs soft tissues
- Congenital flexural limb deformities:
- Apparent at or shortly after birth
- Reduction of functional length of the musculoskeletal unit
- Contracture of the SDFT & DDFT Fetlock; carpus
- Contracture of the DDFT Coffin joint
- Multiple structures usually affected
- Extensor tendon rupture
Clinical Signs of Flexural Limb Deformities
- One or more limbs
- Carpus (most common) or fetlock
- Pastern, tarsus, coffin uncommon
- Fetlock:
- Knuckle over at the fetlock
- Severe cases walk on the dorsal fetlock
Diagnosis of Flexural Limb Deformities
- History: Problem at birth or during early growth
- Physical examination:
- Unable to straighten limbs manually
- May have concurrent digital extensor tendon rupture (swelling over dorsal lateral carpus)
Treatment of Flexural Limb Deformities
- Medical treatment (early or mild to moderately affected foals):
- Physical therapy: Extend limb for 10-15 minutes 4 to 6 times daily
- Oxytetracycline in the first 2 weeks: 2-4 g IV (44mg/kg)
- NSAIDs: Care with dose
- Coaptation (bandages, PVC splints, compression boots, glue on toe extensions)
- Surgery (usually last resort; superior check ligament desmotomy, inferior check ligament desmotomy, flexor tendon tenotomy)
Prognosis of Flexural Limb Deformities
- Best prognosis for foals that can stand, ambulate, and nurse
- Respond in the first 2 weeks for athletic performance
- Carpal contracture cases can take longer
- Poor if unable to stand or there is deformity of the joints
Equine Osteochondrosis (OCD)
- Failure of cellular differentiation in growing cartilage in metaphyseal growth plates and articular cartilage resulting in thickening or retention of cartilage
- i.e. failure of endochondral ossification
Osteochondritis Dissecans (OCD)
- Disruption of the articular surface
- Clinical signs due to inflammation:
- Degrading cartilage causes an inflammatory response releases cytokines Potentially causes nerve endings to sense pain joint pain
Subchondral Bone Cysts (SBC)
- Invagination of thickened plug of abnormal retained cartilage with various degrees of necrosis and inflammation
- +/- Disruption of the articular surface
Aetiopathogenesis of OCD/SBC
- Heredity/Genetic predisposition
- E.g. 25-35% of variation in occurrence in the hock in SB horses
- E.g. Quantitative Trait Loci (QTL) associated with OCD in TB and Hanoverian WB
- Nutrition:
- High energy diets – High soluble CHO content
- High phosphorus diets
- Copper deficiency
- Excessive zinc & cadmium
- Biochemical trauma:
- Exercise is critical for normal bone and tendon development
- Conformation & increased body size may cause abnormal stress on joints and physes
- SBC induced following trauma (e.g. stifle)
- Growth and Body size:
- Large, rapidly growing animals
- Most intense phase of growth occurs in the first 3 months
- Draught breeds – Prevalence is not higher [than other breeds]
- Not described in ponies
Clinical Presentation of OCD/SBC
-
Typical pattern:
- 1-2 lesions in characteristic locations (e.g. stifle, hock, fetlock)
- Often bilateral
-
Atypical pattern:
- Multiple articular + physeal lesions in characteristic and other random sites
- Guarded prognosis
Diagnosis of OCD/SBC
- Clinical signs & radiographic signs Pretty straightforward diagnosis if you have both
- Clinical signs & no radiographic signs Lesions seen only with arthroscopy or MRI/CT
- No clinical signs but positive radiographic findings (“occult lesions”)
- Often seen in pre-purchase exams – Problematic as they have no clinical signs
General Clinical Signs of OCD/SBC
- Young horse
- Effusion
- +/- Lameness:
- Inflammation due to synovitis
- Necrotic tissue debris
- Inflammatory cytokines
- Increased intra-osseous pressure
Osteochondrosis of Tarsocrural (Tibiotalar) Joint
-
Common areas of OCD:
- Distal intermediate ridge of the tibia (DIRT) - MOST COMMON
- Lateral trochlear ridge (LTR) of the talus
- Medial malleolus (MM)
- Medial trochlear ridge (MTR) of the talus
Signalment of Tarsocrural OCD
- Usually weanling or yearlings; Young horses in training
- Most common in Standardbreds
- Less common in TB, quarter horses, Arabians, Warmbloods and draught horses
Clinical Signs of Tarsocrural OCD
- Tarsocrural effusion (bog spavin)
- Lameness uncommon
- If present, is more common in horses > 2 years old
- “Occult” lesions may be seen on x-rays without clinical signs
Diagnosis of Tarsocrural OCD
- Young horse plus effusion without lameness = Suspect
- Radiography:
- Triangular osteochondral fragment off DIRT (most common)
- Irregularity of the lateral trochlear region +/- fragments
- Lesions frequently bilateral (~45-50% of Standardbred cases, ~70% of draught horse cases)
- X-rays may not accurately depict the amount of cartilage damage (ulceration)
- Lesions not observed on x-rays may be observed on arthroscopy
Treatment of Tarsocrural OCD
-
Arthroscopy:
- Treatment of choice
- Shorter convalescence
- Better function and a cosmetic result
- Mini arthrotomy for larger fragments
-
Arthrotomy:
- Less preferred treatment
- Longer convalescence
- Greater risk of complications
- Used for some very large DIRT fragments
Prognosis of Tarsocrural OCD
- Racehorses:
- Good if you get to them early (75-80% return to performance)
- Poorer prognosis if there is articular cartilage erosion or degeneration
- Marked defects/degeneration in the trochlear ridges = bad
- Non-racehorses:
- ~75% synovial effusion resolves
- May take 12-24 months for effusion to resolve
- Draught horses:
- ~60% synovial effusion resolves
- Tend to have more marked synovial effusion
Osteochondrosis of Stifle/Femorotibial Joints
- Femoropatellar joints:
- Lateral trochlear ridge of the femur (FLTR) - Most common femoropatellar OCD
- Medial trochlear ridge of the femur (FMTR)
- Patella: Usually concurrent with a trochlear lesion
- Femorotibial joints:
- ~70% of the femorotibial joints and femoropatellar joints communicate with each other
- Subchondral bone cysts (more common)
- Medial femoral condyle - Most common site of equine SBC’s
- Highest load bearing part of the stifle (more than the lateral condyle)
- Proximal tibia (sometimes)
- Medial femoral condyle - Most common site of equine SBC’s
Femorotibial OCD (Uncommon)
Signalment of Femorotibial OCD
- Most cases presented at < 2yo
- ~56% diagnosed in less than 1yo, ~80% < 2 y old
- Most common in TB, quarter horses, Arabians, warmbloods
- May be diagnosed as early as 6 months of age with careful observation
Clinical Signs of Femorotibial OCD
- Distension of the FEMOROPATELLAR JOINT (most consistent)
- Lameness (none to severe depends on the severity of the lesion)
- Reduced cranial phase and foot arc
- ~60% bilaterally affected
Diagnosis of Femorotibial OCD
- Signalment & clinical signs (young, effusion, no history of trauma)
- Lameness examination (gait)
- Radiography:
- Caudolateral to craniomedial view + Caudocranial oblique
- Irregular/flattened FLTR (lateral trochlear region)
- May be hard to see in foals
- Ultrasound:
- Disruption of cartilage in LTR (dip in continuity)
Treatment for Femorotibial OCD
- Conservative (mild cases):
- Restricted exercise & confinement
- Plus diet management
- Must be monitored – radiographs (may not be evident)
- Arthroscopy (recommended)
- All cases with loose bodies and/or large radiographic lesions
Prognosis of Femorotibial OCD
- Depends on lesion size, location:
- Lesion < 2 cm long: 78% success
- Lesion 2-4 cm long: 63% success
- Lesion > 4 cm long: 54% success
- Concurrent FLTR, FMTR and/or patella lesions have a poorer prognosis
- Multiple lesions in the joint = poor prognosis
Femorotibial SBC
Signalment of Femorotibial SBC
- Most often occurring on the medial femoral condyle
- Usually < 2yo on presentation; Most 1-3yo (range 6mo – 15yo)
- Most common in Quarter horses &Arabians; Tend to see in TB in NZ
- Owner’s usual complaint is lameness (most consistent initial finding)
Clinical Signs of Femorotibial SBC
- Lameness: usually < grade 3/5
- Usually unilaterally lame even if lesions are present in both
- Few may be bilaterally lame
- Exacerbated by exercise +/- Loss of muscle mass
- Swelling/effusion absent or minimal
- Asymptomatic SBCs frequently occur
Diagnosis of Femorotibial SBC
- Signalment & clinical signs
- Lameness exam
- Radiography:
- Flexed lateral view most rewarding
- X-ray both stifles – bilateral common
- Circumscribed area & sclerotic margin
Treatment of Femorotibial SBC
- Consider: lesion size, 2° changes, age, lameness, cost, intended use
- Conservative (not very rewarding in most horses)
- Rest & NSAIDS
- Medication of joint – Corticosteroids (e.g. betamethasone)
- Remodelling takes longer
- If no improvement after 3-4 months Operate
- Arthroscopy (recommended for large lesions and cases where the horse is lame)
- Debridement & lavage
- ± cancellous bone grafting for large cysts
- Screw compression
Prognosis of Femorotibial SBC
- Depends on the area of the joint surface affected, 2o changes, chronicity, etc.
Equine Joint Disease
- Most common equine health issue.
- Most common cause of lameness, impaired mobility, and loss of quality of life for humans, horses, and dogs.
- Trauma-induced joint injury can be mild to catastrophic, ranging from acute synovitis to chronic OA.
Joint Anatomy & Biochemistry
- Joints are classified into three anatomic classes: fibrous, cartilaginous, and synovial.
- Joints can be simple or composite in complexity.
- Joints can be high or low motion, including hinge and ball & socket types.
- Synovial joints consist of subchondral bone, articular cartilage, synovial fluid, and a joint capsule.
- Subchondral bone: Provides support for joint structures.
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Articular cartilage: Specialized tissue that covers joint surfaces, resisting compression and shear forces.
- Load-bearing cartilage: Found in weight-bearing areas.
- Non-load-bearing cartilage: Found in areas with less force.
- Synovial fluid: Lubricates the joint and provides nutrients to the articular cartilage.
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Joint capsule: Encloses the joint and contains the synovium.
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Synovium: Inner membrane responsible for producing synovial fluid and containing cells of mesenchymal origin.
- Type A cells: Macrophages which are phagocytic.
- Type B cells: Fibroblasts involved in secretion and synthesis of structural, anabolic, and catabolic molecules.
- Fibrous layer: External layer of the joint capsule, providing strength and support.
- Internal layer: Inner layer of the joint capsule, lining the joint cavity.
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Synovium: Inner membrane responsible for producing synovial fluid and containing cells of mesenchymal origin.
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Ligaments: Strong, fibrous bands that connect bones to bones and provide stability to the joint.
- Intra-articular ligaments: Located within the joint capsule.
- Peri-articular ligaments: Located outside the joint capsule.
- Muscles and tendons play a role in joint movement and stability.
- Articular cartilage is avascular (lacks blood supply) and aneural (lacks nerves), making it slow to heal and susceptible to degeneration.
- Resisting compression: Through its composition of polysulfated glycosaminoglycan (PSGAG) and hyaluronic acid (HA).
- Resisting shear and tension: Through its collagen type II structure.
- Doesn't regenerate: Making cartilage damage permanent and difficult to repair.
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Synovial fluid biochemistry:
- Contains plasma ultrafiltrate with elevated HA.
- Minimal nucleated cells (less than 1x109/L).
- Composed mainly of synoviocytes, lymphocytes, and monocytes (90%).
- Small portion composed of neutrophils (less than 10%).
- Plays a role in joint nutrition and lubrication, through its HA content and GAG-associated water in cartilage.
Joint Response to Injury
- Traumatic arthritis is OA that develops after trauma, either from a single event or repetitive episodes.
- Other initiators of OA:
- Unmanaged clinical osteochondrosis.
- Post-recovery septic arthritis.
- Cuboidal bone hypoplasia.
- Manifestations associated with joint trauma:
- Synovitis (inflammation of the synovial membrane and fluid).
- Capsulitis (inflammation of the fibrous joint capsule).
- Sprain (injury to joint ligaments).
- Subchondral bone microfracture and sclerosis.
- Intra-articular fractures (affecting articular cartilage and/or subchondral bone).
- Meniscal tears.
Classification of Traumatic Joint Injuries
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Type I: Traumatic synovitis/capsulitis WITHOUT cartilage or major supporting structure damage.
- Examples: Acute synovitis, most sprains.
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Type II: Trauma with damage to the articular cartilage or major supporting structures.
- Examples: Severe sprains, intra-articular fractures, meniscal tears.
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Type III: Post-traumatic OA.
- Progressive deterioration of cartilage, bone, and soft tissues.
Trauma-Induced Joint Disease: Clinical Signs and Diagnosis
- Clinical signs:
- Effusion (excessive synovial fluid).
- Swelling (soft tissue and bone).
- Pain (lameness and pain on flexion).
- Dysfunction (altered range and type of movement).
- Diagnosis:
- Physical examination and lameness assessment.
- Imaging (radiography, ultrasound, CT, MRI).
- Scintigraphy and thermography.
- Synovial fluid analysis.
- Arthroscopy.
Synovitis & Capsulitis (Type I)
- Etiology/pathogenesis:
- Acute vs. chronic.
- Preliminary event for OA development.
- Connective tissue degrading enzymes (e.g., metalloproteinases and proteinases).
- Cytokines and inflammatory mediators initiate and prolong cartilage damage.
- Clinical signs:
- Primary synovitis (effusion without radiographic signs of bony change).
- Mild to moderate lameness (quick improvement).
- Differentiation between primary (synovial membrane), secondary (cartilage/bone/ligament), and infectious (bacteria, fungal, mycoplasma) synovitis is crucial.
- Diagnosis:
- Synovial fluid analysis:
- Total protein: Normal: 18 +/- 3 g/L.
- Abnormal: > 25 g/L.
- Severe inflammation: > 40 g/L.
- Cell counts: Normal: 5-19 x 109/L.
- Grey zone: 10-30 x 109/L.
- Strong indication of infectious arthritis: > 30 x 109/L.
- Total protein: Normal: 18 +/- 3 g/L.
- Synovial fluid analysis:
Villonodular Synovitis (Type I+)
- Excessive synovial proliferative response.
- Commonly found in the dorsoproximal fetlock and other regions.
- Thickening palpable over the dorsal fetlock.
- Diagnosed through radiographs and ultrasound.
- Often unresponsive to intra-articular therapy.
- Arthroscopic debridement is indicated.
Sprains & Dislocations
- Injury of the supporting ligaments due to excessive forced movement.
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Mild sprains (Type I):
- Minimal ligament fibers disrupted with potential hemorrhage.
- Capsulitis or synovitis (intra-articular ligament).
- Management: Rest, ice, support bandage, and NSAIDs.
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Moderate sprains (Type I II):
- Portion of the ligament torn with functional impairment.
- Variable severity of tears.
- Some heal by fibrosis.
- Management: Rest, ice, support bandage, and NSAIDs.
- Arthroscopic debridement if intra-articular.
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Severe sprains (Type II):
- Partial/Complete disruption of the joint due to loss of ligament integrity.
- Damage to fibrous capsule, menisci, and tendons.
- Instability results in more severe pain.
- Management: Surgical reconstruction and splint/cast, arthrodesis (e.g., pastern joint).
Other Traumatic Injuries (Type II)
- Tearing of intra-articular ligaments and meniscal tears.
- Intra-articular fractures: Frequently accompanied by capsulitis/synovitis.
- Examples: Carpal "chip" fractures and slab fractures, proximodorsal P1 "chip" fractures, sesamoid fractures.
Intra-articular Fractures (Type II)
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Carpus:
- Acute onset: Lameness, effusion, pain on palpation/flexion, and potential crepitus.
- Result of chronic stress-related subchondral bone damage: Sclerosis and bone resorption.
- Types: Osteochondral fragment, slab fracture, comminuted fracture.
- Common locations:
- Radial carpal bone.
- 3rd carpal bone.
- Intermediate carpal bone.
- Distal radius.
- Fragments can be free or attached to the joint capsule/bone.
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Fetlock:
- Acute onset: Lameness, effusion, and potential crepitus.
- Result of chronic stress-related subchondral bone damage: Sclerosis and bone resorption.
- Types: Proximodorsal P1/P1, most common, distal MC3/MT4 less common, lateral & medial eminences of proximopalmar/proximoplantar P1.
Signalments, Diagnostics, Treatment, and Prognosis of Equine OA
Osteoarthritis (Type III)
- Progressive and permanent deterioration of articular cartilage and other articular tissue.
- End-stage result of:
- Severe trauma.
- Repetitive strain injury (wear and tear).
- Inadequately treated injuries/diseases (e.g., synovitis, sepsis, osteochondrosis).
- Clinical signs:
- Lameness (pain).
- Early stages initiated by capsulitis/synovitis.
- Progressive joint dysfunction over time.
- Chronic swelling, joint stiffness, reduced range of motion.
- Palpable bony incongruence and loss of normal joint symmetry.
- Diagnosis:
- Lameness examination: Localisation of the affected joint.
- Radiography:
- Loss of joint space.
- Osteophytes (articular bone spurs).
- Sclerosis.
- Enthesiophytes (mineralization of the joint capsule).
- MRI: Evaluation of cartilage and soft tissues.
- Arthroscopy: Anatomic evaluation and assessment of the severity of cartilage damage.
Treatment & Prevention of OA
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Type I (Synovitis/Capsulitis):
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Objectives:
- Alleviate immediate inflammation.
- Prevent permanent fibrosis.
- Treat and resolve the underlying cause if possible.
- Minimize the development of OA.
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Management:
- Early, timely, and appropriate pharmacologic intervention.
- Ancillary therapy (e.g., cold therapy, limb support).
- Minimizing instability.
- Rehabilitation and maintenance of joint health.
- Control inflammation: NSAIDs, hyaluronan, corticosteroids, cold therapy.
- Protect cartilage: PSGAG, pentosan polysulphate.
- Support limbs: Padded bandages.
- Maintain mobility: Physical therapy to prevent fibrosis.
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Objectives:
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Type II (Articular Cartilage Damage):
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Objectives:
- Repair/regenerate damaged cartilage.
- Prevent further cartilage degeneration.
- Minimize pain and improve function.
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Management:
- Arthroscopy: Debridement of loose fragments and flaps, lavage, and treatment of partial-thickness defects.
- Osteochondral grafts.
- Stem cell therapy.
- Post-operative care and rehabilitation.
- DMOADs (e.g., Cartrophen).
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Objectives:
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Type II (Intra-articular Fractures):
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Objectives:
- Stabilize the fractures.
- Reduce inflammation.
- Promote healing.
- Restore joint function.
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Management:
- Arthroscopy: Debridement of loose fragments/flaps, lavage, and reduction/fixation of larger fragments.
- Post-operative support bandage and NSAIDs.
- Stall rest (~2 weeks).
- Rehabilitation plan: Hand walking, passive mobilization, swimming, or turnout (~8 weeks).
- Slab fractures require ~6 months to heal.
- Post-operative medication plan: Hyaluronan, PSGAG, corticosteroids (IA, IM, IV).
- Prognosis: Determined by joint(s) injured, fracture configuration, injury severity, and cartilage loss.
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Objectives:
- **Type III (OA): **
- Objective: Maintain quality of life.
- Palliative relief: Minimize pain, discomfort, and dysfunction.
- Arthrodesis: Fusion of low-motion joints (e.g., pastern joint) to provide stability in infected or traumatized joints.
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Management:
- Alleviate inflammation.
- Prevent fibrosis.
- Treat the underlying cause.
- Early intervention.
- Rehabilitation and maintenance of joint health.
- Pharmacologic intervention: NSAIDs (e.g., phenylbutazone, flunixin meglumine, meloxicam, ketoprofen), hyaluronic acid (IA or IV), PSGAGs (e.g., Cartrophen), pentosan polysulphate, IA corticosteroids (e.g., triamcinolone acetonide, betamethasone, methylprednisolone acetate, dexamethasone phosphate, isofluprednisolone).
- Biologics: Autologous conditioned serum, bone-derived mesenchymal stem cell therapy, fat-derived mesenchymal stem cell therapy, IRAP, platelet-derived therapy.
- Oral supplements: GAGs/HA/glucosamine (e.g., Flex-free, Syno-Flex, Cosequin).
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Physical therapy:
- Cold application: Applied during the inflammatory phase (0-4°C for 30 minutes).
- Limb immobilization: Prevent further injury and support unstable joints.
- Limb mobilization: Prevent capsular fibrosis and maintain mobility.
- Other therapies: Acupuncture, therapeutic ultrasound, soft tissue lasers, shockwave therapy.
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Prognosis:
- High-motion joints: Poor long-term prognosis.
- Low-motion joints: May tolerate OA for many years with treatment.
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Test your knowledge on equine orthopedic disorders, including angular limb deformities and cuboidal bone hypoplasia. This quiz covers conditions affecting athletic performance and their clinical signs, offering insights into common developmental orthopedic issues in horses.
