Final Flashcards
What is the primary determinant of equine joint health?
Articular cartilage
What component of equine articular cartilage synthesizes, organizes, and regulates the composition of the extra-cellular membrane?
Chondrocytes
What type of collagen is present in equine articular cartilage?
Type 2
Which component of equine articular cartilage counteracts the tensile stresses at the joint surface?
Collagen
What type of stress does collagen counteract at the joint surface?
Tensile
Which component of the equine articular cartilage resists compressive forces?
Aggrecan (a proteoglyan)
What force does aggrecan resist?
Compressive
How does articular cartilage receive nutrition?
Motion!
Cartilage has no blood supply
Compression expels water and soluble waste
Relaxation brings in water and soluble waste
What molecule contributes to synovial fluid viscosity?
Hyaluronan
What is the function of the synovial fluid?
Lubricate gliding surface
Nutrition supply and waste removal from cartilage
What is the Matrix Metalloproteinase inhibitor?
Tissue Inhibitor of Metalloproteinases (TIMP)
What are aggrecanases?
A distintegrin and metalloproteinase thrombospondin motifs
ADAMTS
What are the inflammatory cytokines in articular cartilage and what do they do?
IL-1 and TNF-a
Increase production of MMPs, oxygen free radicals, and prostaglandins
Inhibit collagen and aggrecan synthesis
Upregulate each other
What is the function of prostaglandins in articular cartilage?
Proteoglycan degradation
Sensitizes nerves to mediators of pain
Production stimulated by IL-1
What types of repair does cartilage undergo?
- Intrinsic: chondrocyte synthetic activity
- Extrinsic: cells from marrow cavity, requires penetration of subchondral bone
- Matrix flow: cartilage melts into fill lesion
What are the major classes of equine joint disease?
- Developmental orthopedic disease
- Traumatic/degenerative arthritis
- Septic arthritis
- Immune-mediated polyarthritis
What are examples of equine developmental orthopedic diseases?
Osteochondrosis
Osteochondritis dessicans
Subchondral bone cysts
Delayed ossification
T/F: traumatic/degenerative osteoarthritis causes irreversible changes to the joint
True
What tissue changes are seen with equine osteoarthritis?
Synovitis
Capsulitis
Ligamentous or meniscal injury
Primary cartilage injury
What is the gold standard in diagnosing equine osteoarthritis?
Arthroscopy
What clinical signs are associated with equine osteoarthritis?
Pain
Synovial effusion
Decreased range of motion
Local inflammation
What would you expect to see on radiographs of a horse with osteoarthritis?
Enthesiophytes
Osteophytes
Joint space narrowing
Subchondral bone sclerosis and/or lysis
Osteochondral fragments
For horses with osteoarthritis, does the severity of radiographic changes correlate with the amount of pain?
NO
What are the main goals in treating equine osteoarthritis?
Remove inciting cause*
Slow the progression of degeneration
Alleviate clinical signs
Restore function
Improve quality of life
How do you treat equine osteoarthritis?
REST
Surgery: remove inciting cause, debridement, repair stimulating techniques, cartilage repair
Medical tx
What types or surgery exist for the treatment of osteoarthritis?
Graft procedures
Arthrodesis
Facilitated ankylosis
Joint stabilizing surgeries (TPLO, TTA, etc)
Joint replacement
What types of medical therapy is used to treat osteoarthritis?
NSAIDs
Corticosteroids
Hyaluronan
Polysulphated glycoaminoglycan
Pentosan polysulphate
What types of corticosteroids are used to treat equine osteoarthritis and what route of administration is most common?
Methylprednisolone acetate: low motion joints
Triamcinolone acetonide: high motion joints
Intra-articular administration
What is the main functions of hyaluronan in the medical treatment of equine osteoarthritis?
Lubrication and anti-inflammatory
What is the function of polysulphated glycosaminoglycan in the medical treatment of equine osteoarthritis?
Stimulates endogenous hyaluronan synthesis
Condroprotective effects
What is the function of pentosan polysulphate in the medical treatment of equine osteoarthritis?
Decreased fibrillation
For early OA only
What biologic therapies exist for the treatment of equine osteoarthritis?
IRAp or ACS
PRP
Stem cells
Gene therpy
What are neutraceuticals?
Supposedly help with osteoarthritis
Do not require FDA approval for safety and efficacy
Glucosamine, chondroitin sulfate, cosequin, herbs, antioxidants etc.
What are the 3 types of equine septic arthritis?
Traumatic
Iatrogenic
Hematogenous
T/F: septic arthritis in horses is always an emergency
True
What are the different types of equine hematogenous septic arthritis?
Affect foals!
S-type: synovial membrane and fluid
E-type: subchondral bone of epiphysis -> extends into joint
P-type: physis, may extend into joint
How do you diagnose equine septic arthritis?
Clinical signs
Rads
Synovial fluid (clin path and culture)
Does a lack of bacteria in synovial fluid analysis rule out septic arthritis?
No, you will rarely see bacteria
Mostly will see neutrophils
What organisms would you expect in a synovial fluid culture in a horse? Foal? Cow?
Horse: staph aureus
Foal: enterobacteriaceae, strep, rhodococcus, actinobacillus
Cattle: A. Pyogenes, strep, salmonella, e. coli, mycoplasma
How do you treat septic arthritis?
Broad-spectrum systemic antimicrobial
Synovial lavage
Intra-articular antimicrobials
Regional antibiotic perfusion
Bandage
Analgesia
Arthrotomy
What type of antibiotic administration results in the highest antimicrobial concentration in the synovium?
Intra-articular
When do you stop treatment for septic arthritis?
When there is a significant improvement in effusion and lameness
DO NOT rely on WBC count
What are the 3 criteria for diagnosing immune-mediated polyarthritis?
- Inflammatory process affecting synovium of two or more joints
- No identifiable infectious component
- Responsive to immunosuppressive therapy
What is infraspinatus contracture?
Hyperextension of the forelimb, adduction of the elbow, and abduction of the paw
Caused by acute, traumatic injury to the scapular muscle
Not painful
What is the treatment for infraspinatus contracture?
Tenotomy
Excellent prognosis, full return to function
What type of scapulohumeral luxations are common in small breed dogs? Large breed dogs?
Small breed: medial
Large breeds: lateral
Lateral scapulohumeral luxations are a result of the loss of integrity in what structures?
Infraspinatus muscle
Lateral glenohumeral ligament
Lateral joint capsule
In medial scapulohumeral luxations, what is the success of reduction dictated by?
Integrity/conformation of the glenoid cavity
What two surgical approaches exist to correct a medial scapulohumeral luxation?
- Medial transposition of biceps tendon
2. Arthrodesis
What is bicipital tenosynovitis and how do you treat it?
Chronic, often intermittent lameness caused by inflammation of the biceps tendon, resulting in osteophytosis and mineralization of the humerus
Tx: intra-articular steroid injection or bicipital tendon release
What is the most common type of displacement in traumatic elbow luxations?
Laterally displaced radius and ulna
NEED ORTHOGONAL VIEWS!
How do you treat traumatic elbow luxations?
Reduce ASAP!
Closed or open. Flex the elbow to relocate the anconeal process.
Coapt limb in extension
What types of dogs are prone to congenital elbow luxation?
Small breeds and bulldogs
What is required for normal function to be established in a limb of a dog with a congenital elbow luxation?
Early surgical intervention
What are causes of growth plate disturbances that result in angular limb deformities?
Trauma
Developmental disturbances
Inflammatory disease
What results from premature closure of the distal ulnar physis?
Curved radius
What types of dogs are affected by carpal hyperextension injuries?
Large breed dogs, particularly hunting dogs
What structures are damaged in carpal hyperextension injuries?
Palmar fibrocartilage and ventral carpal ligaments
What causes carpal hyperextension injuries?
Usually trauma, but can also be degenerative
What are the treatments for carpal hyperextension injuries and which is most effective?
Coaptation
Individual ligament repair
Partial carpal arthrodesis
Pancarpal arthrodesis: *most effective
What type of radiographic view do you need to identify the point of instability in a carpal hyperextension injury?
Stressed view
What is the definition of osteochondrosis?
A disturbance in the normal process of endochondral ossification
In small animals, how do you differentiate between osteochondrosis and osteochondritis dessicans?
With OC, animals will not be lame
With OCD, animals will be lame
What are common sites of osteochondrosis in small animals?
Humeral head Humeral condyle Coronoid process Anconeal process Femoral condyles Patella Trochlear ridges of the talus
In small animals, OCD of what bone will reliably cause lameness?
Humeral head
What is the prognosis for return to normal function in small animals that have arthrotomy/arthroscopy for OCD?
Excellent
What are the subcategories of elbow dysplasia?
Ununited anconeal process
OC/OCD of humeral condyle
Fragmented coronoid process
At what age do clinical signs of elbow dysplasia appear?
5-8 months
Mild intermittent lameness, supinated stance, and circumduction of affected limb during the swing phase of stirde are associated with which forelimb disease (small animals)?
Elbow dysplasia
What sex and breeds are predisposed to ununited anconeal process?
Male:female 2:1
German shepherd and Basset hounds
What radiographic view is best to diagnose ununited anconeal processes?
Flexed lateral
At what age can you deem the anconeal process ununited?
20 weeks
What is the treatment for an ununited anconeal process?
Excision of the anconeal process
Stabilization of the anconeal process (lag screw)
Proximal diaphyseal ulnar osteotomoy
What approach to the elbow do you take in treatment of ununited anconeal process?
Caudolateral approach
In small animals, OCD of the humeral condyle mostly affects what part of the condyle?
Trochlea (medial portion)
Which dog breed is most affected by OCD of humeral condyle?
Labrador Retrievers
What radiographic view is best for diagnosing OCD of the humeral condyle?
Craniolateral-caudomedial oblique projection
How can you diagnose fragmented coronoid process from histopathology?
Diffuse microcracks in the subchondral bone consistent with fatigue microdamage
Indicates abnormal biomechanics that lead to asymmetric loading of the elbow
What morphological change to the ulnar notch puts pressure on the medial coronoid process?
It’s more ovoid
How do you diagnose fragmented coronoid process?
Hard to visualize on radiographs
Generally look for secondary degenerative changes in the absence of a UAP or OCD
Usually not present before 7 months of age
What is the treatment for a fragmented coronoid process?
Optimal treatment has yet to be defined
Surgery does nothing for development of DJD
Better outcomes with arthroscopy/Arthrotomy
What is the prognosis for elbow dysplasia?
Degenerative changes are likely to progress regardless of surgical excision
Most dogs are functional pets but questionable athletes or working dogs
What is panosteitis and how does it present?
Intramembranous ossification that spreads linearly along the central medullary artery and vein +/- endosteal/periosteal reaction
Presents as reoccurring shifting lameness, lethargy, anorexia, fever
Idiopathic, self-resolving
What is the treatment for panosteitis?
Analgesics and anti-inflammatories
Will re-occur every 2-4 weeks
What is the definition of hip dysplasia?
Abnormal development of the CF joint resulting in subluxation/luxation and/or degenerative joint disease (DJD)
Usually large breed dogs
What are the consequences of joint laxity in dogs with hip dysplasia?
Capsular thickening
Cartilage fibrillation
Cartilage erosion
Abnormal joint development
What is the clinical presentation of hip dysplasia?
Young animals: < 12 mo old, pain, laxity, minimal radiographic degeneration
Mature animals: DJD, bony remodeling
What key points in the history may suggest a dog has hip dysplasia?
Reluctance to exercise
Difficulty rising
Bunny hopping
Clicking
Chronic symmetric hind limb lameness
What exam findings will be suggestive of hip dysplasia in a young patient?
Lameness
Painful palpation (extension and abduction of hips)
Muscle atrophy
Joint laxity (+ ortolani sign)
What exam findings will be suggestive of hip dysplasia in a mature patient?
Lameness
Painful palpation (extension and abduction of hips)
Crepitus
Decreased range of motion
What is the Ortolani test?
Assess joint laxity associated with hip dysplasia
Anesthesia required
Lateral recumbency, stifle flexed 90 degrees, limb perpendicular to spine
Apply axial pressure, abduct limb, feel and listen for a “click” or “thunk” (reduction)
Continue axial pressure, adduct limb, feel for subluxation
What are possibilities with a negative Ortolani test?
Animal is normal
Capsular fibrosis has eliminated laxity
Irreducible luxation of the femoral head
Acetabular infilling with bone
Insufficient force to subluxate the femoral head
Inadequate muscle relaxation
How will radiographs be different for young vs mature dogs with hip dysplasia?
Young: coxofemoral subluxation, minimal DJD
Mature: coxofemoral malformation, moderate DJD
What is normal % acetabular coverage over the femoral head?
> 60%
What is OFA?
Orthopedic Foundation for Animals
Subjective grading of hip dysplasia by radiologist
Grading scale 1-7
Animals must be 2 years old
What is PennHip?
Objective measurement of hip laxity
Greater predictive value than OFA
Valid in animals >16 weeks of age
What is the Dorsolateral Subluxation Test?
Radiographic study to assess hip subluxation
What are non-surgical treatment options for hip dysplasia?
Weight loss
Anti-inflammatory
Chrondroprotection
Controlled exercise
What are the surgical treatment options for juvenile hip dysplasia?
Triple pelvic osteotomy (TPO)
Pubic Symphysiodesis
What is a Triple Pelvic Osteotomy?
Surgical treatment of hip dysplasia
Osteotomy of the ilium, ischium, and pubis
Acetabulum is rotated dorsally and laterally to increase coverage
For animals with little or no DJD and < 10 months of age
What is Pubic Symphysiodesis?
Cauterization of pubic symphyseal growth plate causing premature closure
Unopposed dorsal growth causes rotation outward acetabular rotation
For dogs < 20 weeks of age
What are surgical treatment options for hip dysplasia in a mature patient?
Femoral head and neck ostectomy (FHO)
Total hip replacement
What is the main difference between the results of FHO and total hip replacement?
Total hip replacement results in normal or near normal gait, muscle mass, and range of motion
What are the three major stabilizers of the coxofemoral joint?
Round ligament
Joint capsule
Dorsal acetabular rim
What are the ancillary stabilizers for the coxofemoral joint?
Acetabular labrum
Pelvic muscles
What is the most common type of hip luxation in dogs and cats?
Cranio-drosal
What are the goals of hip luxation reduction?
Stable, concentric reduction
Preservation of articular cartilage
Long-term normal function
When is appropriate to do a closed reduction of a hip luxation?
Non-dysplastic hip
Short duration of luxation
No complicating factors
What are indications for an open reduction of a luxated hip?
Femoral or acetabular fractures
Irreducibility
Instability
Complicating factors
What patient factors must you take into account when doing an open reduction of a luxated hip?
Body weight
Luxation type
Activity level
Integrity of joint capsule
What are indications for a toggle pin in the treatment of hip luxation?
Multiple limb injuries
Early use of theleg
What are indications for capsulorrhaphy in treatment for hip luxation?
Intact joint capsule
Associated to other techniques
(Has highest success rate)
What are indications for extra-capsular prothesis in treatment for hip luxation?
Non-repairable capsule tears
Persistent instability
What are complications associated with De-Vita pins in treatment for hip luxation?
Sciatic nerve injury
Pin migration
Pin-tract drainage
Injury to the femoral head
Septic arthritis
What are the indications for transarticular pins in treatment of hip luxation and what are the complications associated with them?
Indications: recurrent and chronic luxations
Complications: rectal perforation, pin migration, pin breakage
What are the primary and secondary restraints of the stifle in small animals?
Primary: cranial and caudal cruciate ligaments
Secondary: menisci, collateral ligaments, joint capsule
What are the primary functions of the CCL?
Primary restraint against:
- Cranial tibial translation
- Stifle hyperextension
Contributes to control of:
- Internal tibial rotation (with caudal cruciate ligament)
What are the three CCL rupture syndromes?
- Acute traumatic CCL rupture
- Early degenerative CCL rupture
- Chronic degenerative CCL rupture
What is early degenerative CCL rupture?
Characterized by progressive, mild lameness, effusion, and mild osteoarthritis
No instability
Often bilateral
More common in mature dogs
Progresses to complete rupture
What is chronic degenerative CCL rupture?
Characterized by intermittent lameness, periarticular fibrosis (medial > lateral)
Instability present
Moderate OA
Often bilateral
What is the mechanism behind Chronic degenerative CCL rupture?
Degeneration begins within the central core and results in loss of fibroblasts and condroid metaplasia
Unsuccessful remodeling in response to cyclic loading
Progressive transformation in fibrocartilage
No reparatory response
What is the incidence of concurrent meniscal injury with CCL rupture?
50-90%
What structures firmly attach the medial meniscus to the tibia?
Cranial menisco-tibial lig
Caudal menisco-tibial lig
Joint capsule
Medial collateral lig
What structures loosely attach the lateral meniscus to the tibia and femur?
Cranial menisco-tibial lig
Menisco-femoral lig
What is the mechanism of meniscal tear?
Meniscus is a secondary restraint
CCL rupture
Meniscus becomes primary restraint
Caudal pole is trapped between the femoral and tibial condyles
What is responsible for meniscal injury?
Wedge phenomenon of the caudal pole of the meniscus
What two test can confirm CCL rupture?
Tibial drawer and thrust
What is the most important exam finding for dogs with CCL injuries?
PAIN
Especially on extension of the stifle
Will all dogs with CCL injury have a positive tibial drawer or thrust?
No, can have a partial tear
What radiographic finding is indicative of CCL injury?
Joint effusion displacing joint fat pad
How do you decide if a patient needs surgical or medical treatment of CCL injury?
Small dogs and cats respond well to cage rest and NSAIDs
Large dogs need surgical stabilization
What is the goal for standard surgical treatments of CCL injury and what are the different types?
Mimic CCL function!
Extra-articular
Intra-articular
Autogenous lig
Prosthetic lig
What is the function of tibial osteotomies?
Neutralize the cranial tibial thrust
DOES NOT replace the ligament
What is a TPLO?
Tibial Plateau Leveling Osteotomy
Corrective osteotomy for CCL injury
Circular cut causal to tibial crest
Reduced caudal angulation of plateau
What is patellar luxation?
Permanent or intermittent displacement of the patella to either side of the stifle
MEDIAL luxation is most common
More common small breed dogs
What is the most common type of patellar luxation?
Medial
What is the etiology for patella luxation?
Disruption of normal extensor mechanism alignment causes the patella to be pulled medially or laterally
What is the grading system for patellar luxation?
Grade 1 (IN/IN): Can be manually luxated but will return to normal position, frequently a nonclinical incidental finding
Grade 2 (IN/OUT): Usually in normal position, but can be luxated and will remain luxated but will spontaneously reduce
Grade 3 (OUT/IN): Luxated most of the time but can be manually reduced. Spontaneously luxates and remains luxated.
Grade IV (OUT/OUT): Luxated and cannot be reduced. Usually associated with conformation abnormalities.
What are the clinical signs associated with patellar luxation?
Frequently an intermittent non-weight-bearing lameness
Lameness tends to increase with grade
Grade IV luxations may have severe conformational defects
What are the two categories of treatment for patella luxation?
Reconstructive procedures: alter the anatomic abnormalities
Stabilizing procedures: attempt to maintain the patella in the normal position
What reconstructive procedures exist for treatment of patellar luxation?
Deepening of the femoral trochlea
Tibial tuberosity transposition
Corrective femoral and tibial osteotomies
What stabilizing procedures exist for treatment of patellar luxation?
Retinacular/capsular imbrication
Capsulectomy
Fabellar to patella suture
Fabellar tibial anti-rotational suture
What is the prognosis for medial patellar luxation?
Most improve with surgical treatment
Reoccurrence is usually a lower grade -> reoperate
What is osteochondritis dessicans?
Defect in endochondral ossification that results in cartilage flap
Seen in immature large breed dogs
Causes synovitis and subsequent osteoarthritis
What are the most common sites of osteochondritis dessicans in the hindlimb?
(More common in the forelimb)
Stifle: lateral aspect of femoral condyle
Hock: medial trochlear ridge (prognosis of this site is worst!)
What is the definition of lameness?
An asymmetry of gait due to disorder of appendicular or axial musculoskeletal system
Which limb in horses is most commonly affected by lameness?
Forelimb (bears 60+% of weight!)
What are the most common causes of lameness in horses?
Osteoarthritis
Soft tissue injuries
How is active lameness in horses graded?
AAEP Lameness Score
0/5: Lameness not perceptible under any circumstances
1/5: Lameness is difficult to observe and is not consistently apparent, regardless of circumstances
2/5: Lameness is difficult to observe at a walk or when trotting in a straight line but consistently apparent under circumstances
3/5: Lameness is consistently observable at a trot under all circumstances
4/5: Lameness is obvious at a walk
5/5: Lameness produces minimal weight bearing in motion and/or a complete inability to move
What is palmar foot pain?
Lameness originating from the podotrochlear apparatus of the forelimb
Caused by abnormal, non-physiological biomechanical loading of structures
**QH 7-10 YO
AKA “Navicular Syndrome”
What are the clinical signs of palmar foot pain?
Often bilateral lameness, worse on hard ground or when circling
Choppy gait
Tripping
DDFT thickening, DIPJ effusion
Sensitivity to foot testers
“Blocks” to low palmar digital nerve block, DIPJ, or navicular bursa
How do you diagnose palmar foot pain and how is it treated?
Dx: MRI
Tx: Rest and controlled exercise, Therapeutic shoeing, NSAIDs, IA therapies, Shock wave, Surgical
What is the surgical treatment of choice for palmar foot pain?
Navicular bursoscopy /- digital flexor tenoscopy
Includes debridement of abnormal cartilage and DDFT tears
Reduction of adhesions (DDFT to NSLand bursa)
Observation of flexor surface of navicular bone
What are the surgical treatment options for palmar foot pain?
Navicular bursoscopy +/- digital flexor tenoscopy best
Palmar digital neurectomy (salvage)
What are the 7 types of third phalanx fractures?
1: Wing fracture
2: Articular wing fracture
3: Axial fracture
4: Extensor process fracture
5: Comminuted fracture
6: Solar margin fracture
7: Solar margin fracture in a foal
What breed and limb are second phalanx fracture most commonly seen in?
Western performance AQH
Hindlimbs
What type of surgical fixation exists to treat second phalanx fractures?
Plantar/palmar eminence fractures and comminuted fractures: plating/screw repair with PIPJ arthrodesis
Axial (sagittal) fractures: cortical screw in lag fashion
Osteochondral fragments: arthroscopic removal
What is the treatment for dorsal osteochondral fragments (“chips”) of the first phalanx?
Arthroscopic removal, 6 weeks rest, intra-articular therapies
What causes diaphyseal fractures of the first phalanx?
Torsional and axial forces
“Screwdriver fractures”
What are the treatment options for diaphyseal fractures of the first phalanx?
Box stall rest ~90 days Internal fixation (cortical bone screw place in lag fashion) Arthrodesis Transfixation pin Euthanasia
What is palmar/plantar osteochondral disease “POD”?
Due to repetitive stress injury and results in maladaptive bone remodeling, commonly MC/MT III condylar disease
Predisposes to MC/MT III fractures
What horses are prone to POD and how do you diagnose it?
TB/SB race horses
Diagnose by bone scan, MRI, or CT
What is the treatment for POD?
REST (90+ days)
Continued training worsens and may lead to catastrophic failure!
What parts of the bone are MC/MT III fractures seen in and how are they treated?
MC III - lateral condyle
MT III- Medial condyle
Internal fixation: cortical screw in lag fashion +/- plate
What condition is known as “bucked shins”, what horses are prone to this, and what does this condition predispose them to?
Maladaptive remodeling of the dorsal cortex of mCIII
TB racehorses
Dorsal cortical fractures (commonly incomplete)
What is a “saucer” fracture?
A complete fracture of the dorsal cortex of mc III
What is the treatment for fractures of the dorsal cortex of MC III?
Rest (90+ days)
Osteostixis surgery: Place and remove unicortical screw to allow ingrowth of vessels and bone to heal before returning to training
T/F: traumatic splint bone fractures are often open
True
Usually from a kick from another horse
What disease often accompanies exercise-related splint bone fractures?
Suspensory desmitis
What is the treatment for splint bone fractures?
Closed:
Rest
Removal and rehabilitation of SL
Internal fixation
Open:
Partial splint ostectomy
Internal fixation
What are the three joint compartments of the equine carpus?
Radiocarpal
Middle carpal
Carpometacarpal
What are most equine carpal injuries a result of?
Repetitive axial loading/maladaptive bone remodeling
What is osteochondral fragmentation of the equine carpus and how is it treated?
Fragmentation more common along the medial aspect of the carpus, caused by repetitive stress and hyperextension
Causes lameness and synovitis
Should be removed arthroscopically
What is biarticular “slab” fractures of the third carpal bone, where is the most common site of fracture, and how is it treated?
Fracture of the carpal bone caused by repetitive axial loading and maladaptive bone remodeling
Radial > intermediate facet
Tx: arthroscopic removal or internal fixation
What are the 4 joint compartments of the equine tarsus?
Tibiotarsal
Proximal intertarsal
Distal intertarsal
tarsometatarsal
What is the most common disorder of the tarsus?
Osteoarthritis
What is “bone spavin” and what is the treatment?
Osteoarthritis of the distal intertarsal and tarsometatarsal joints of the tarsus
Tx:
Medical: IA therapies, NSAIDs, chondroprotective agents, corrective shoeing– usually very successful with routine management
Surgical: facilitated ankylosis, cunean tenectomy
What is the largest and most complex joint in the horse?
Stifle
3 bones, 2 menisci, 14 ligaments
What are the three joints of the equine stifle?
Femoropatellar
Medial femorotibial
Lateral femorotibial
What is upward fixation of the patella?
Complication of the stay apparatus in horses
Commonly intermittent
What types of horses are prone to upward fixation of the patella?
Miniature horses: permanent fixation
Young horses (in growth spurts)
Mature horses that are rested for other resons
What are the treatment options for upward fixation of the patella?
Nonsurgical:
Treat primary lameness
Corrective shoeing
Treat secondary joint pain
Pelvic limb and quadriceps strengthening
Medial patellar ligament injections
Surgical:
Medial patellar desmoplasty
Medial patellar desmotomy
Anesthesia of which nerve can help you localize a proximal suspensory desmitis of the hind limb?
Deep branch of the lateral plantar n.
What is the treatment (nonsurgical and surgical) for proximal suspensory desmitis?
Non-surgical: rest and ice
Surgical: fasciotomy (retinaculum)
What are the degenerative orthopedic diseases seen in horses?
Osteochondrosis (OCD and subchondral cystic lesions)
Angular limb deformities (juvenile arthirits)
Flexural limb deformities
Physitis
Cervical Stenotic myelopathy
What is the most common clinical sign of osteochondrosis in horses?
Joint effusion
What are the most common sites of osteochondrosis in horses?
Tarsus: Distal Intermediate Ridge of Tibia (DIRT OCD)
Stifle: Lateral Trochlear Ridge of Femur (LTFR OCD) and Medial Femoral Condyle (MFC subchondral cyst-like lesion)
Metacarpo/metatarsophalangeal joint: Dorsal aspect of the sagittal ridge
What are the most common horse breeds that have osteochondrosis?
Thoroughbred
Quarterhorse
Standard bred
Warmbloods
What is the treatment of osteochondrosis in horses?
Arthroscopy
Rest
Controlled exercise
Drugs (anti-inflammatories, disease modifying agents, regenerative therapies)
What is the most common site of a subchondral bone cyst in horses?
Medial femoral condyle
What radiographic finding is indicative of a subchondral bone cyst?
Lucent subchondral bone surrounded by sclerosis
What are angular limb deformities in horses? What’s the difference between valgus and varus?
Deviation of the limb in the frontal plane
Valgus: lateral deviation of the limb distal to the location of the deformity (away from the center)
Varus: medial deviation of the limb distal to the location of the deformity (towards the center)
What perinatal factors contribute to angular limb deformities in horses?
- Incomplete ossification
2. Periarticular laxity
What developmental factors contribute to angular limb deformities in horses?
- Unbalanced nutrition
2. Excessive exercise or trauma
T/F: slight external rotation and milld valgus of the forelimbs is normal in young foals (< 2-3 months)
True
What treatment options exist for angular limb deformities in horses?
Stall rest
Hoof manipulation (trim on same side, hoof extensions on opposite side as deformity points)
Periosteal elevation
Growth retardation with implant
In which equine joint deformity is it especially important to identify and treat early?
Fetlock (distal MC/MT III)
What is juvenile arthritis and in which location is it most common?
Sequela to incomplete ossification of cuboidal bones
Most common in tarsus
What is the treatment for juvenile arthritis?
No treatment, only prevention
Can give intra-articular steroid, fusion
Poor prognosis
What is a flexural deformity and which location is it most common in?
Deviation of the limb in the sagittal plane
Includes hyperflexion or hyperextension
Carpus/fetlock most common
How do you treat congenital contracture deformities in horses?
NSAIDs
Oxytetracycline (will inc. tendon laxity)
Bandage + splint + stall rest
What is the treatment for hyperextension deformities?
Controlled exercise
Heel extensions
Bandaging
Splints/casts
What causes acquired flexural deformities and which joints are most commonly affected?
Long bone growth»_space; flexor tendon growth
Genetics, nutrition
DIPJ and MCPJ most common
What is “club foot”?
DIPJ deformity caused by relative shortening of the DDFT
Created upright and boxy hoof
Most common in forelimb
Good prognosis if < 90 degrees
What is the treatment (surgical and nonsurgical) for DIPJ deformity?
Non-surgical: reduction in calories, NSAIDs, controlled exercise, toe extension, trim heels, dynasplint
Surgical:
Type 1- inferior check lig desmotomy (ICLD)
Type 2- (>90 degrees) - may require ICLD and DDF tenotomy
What is MCP/TP joint deformity and what are the treatments?
Upright angle or knuckling of fetlock
May be due to relative shortness of SDFT +/- suspensory lig
Worse prognosis than DIPJ
Non-surgical treatment: Same as club foot
Surgical treatment: Superior chec lig desmotomy +/- ICLD, SDF tenotomy
What is equine physitis, how do you diagnose it, and what is the treatment?
Enlargement of one or more physes causing disruption of normal endochondral ossification
Radiographs: increased paraphyseal bone, physeal lysis/sclerosis
Tx: rest, NSAIDs, diet reduction