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Radiology Of Joint Disease

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sihirlifil's version from 2017-09-05 18:38

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Question Answer
Technique for radiographing joints: setting?High mAs, low kVp (high contrast)
Want adequate penetration of bones but also assess soft tissue
Technique for radiographing joints: Receptor system?Fine detail films, screens
Technique for radiographing joints: Grid?When structure >10cm in analog, e.g. hips, shoulders large breed dogs
Digital plate
Scatter correction algorithm in direct digital radiography (minimize scatter)
Technique for radiographing joints: How do you position the patient?Standard (ML and CdCr/CrCd), special projections when needed e.g. flexed, skyline
Center on joint to reduce distortion (flex/extend to localize)
The visible lucent line is composed of (3)Articular cartilage
Synovial fluid
Synovial lining
Components of a joint (10)Articular cartilage
Synovial fluid
Synovial lining
2 or more bones
Joint capsule
Collateral ligaments
Tendons
Sesamoid bones
Periarticular tissue
+/- Fat pads
Joint effusion=Abnormal filling of the joint, increased amount of synovial fluid (leads to soft tissue swelling), hemarthrosis, septic arthritis
Proliferation of synovial lining
Fat pads may become compressed
Fascial planes may displace caudally
Which view is really important for seeing joint effusion in the canine stifle?Mediolateral to help see the fat pad
How to analyze joint effusion?Ultrasound, synoviocentesis, fluid analysis; confirmation by contrast study or ultrasound
Periarticular swelling =Thickening of joint capsule, sollageral ligaments
Swelling of periarticular soft tissue (edema, cellulitis, abscess, hematoma)
How to assess periarticular swelling?Ultrasound
Increased articular opacity:Intraarticular osteochondral fragments (joint mice)
Foci of mineralizaion (menisci (old cats), synovium)
Decreased articular opacity:Gas in joint w/o puncture (vacuum phenomenon)
Iatrogenic gas (synoviocentesis)
Trauma (joint penetration)
Gas-producing bacteria
Joint congruency: normal joint space?Visible, even width
Joint congruency: normal subchondral bone?Smooth, homogenous opacity, well-defined, contrasts with trabecular bone
Joint congruency: bony proliferation?Not present (no osteophytes) (no sharp edges)
Joint congruency means?Articular surfaces of the 2 bones that form a joint should be in contact, separated only by the linear ST opacity created by the articular cartilage, synovium, & synovial fluid
Subluxation =2 bones are in contact, but the contact area is reduced (step formation)
Luxation =2 bones are no longer in contact (often associated with avulsion fractures)
Fracture-luxation = ? Example?Fracture is associated with luxation
Monteggia fracture: ulna frax, radius luxated cranially
Coxofemoral joint most often luxates:Cranially and dorsally
Osteophytes: what are they? Form where?Initially cartilaginous, bony outgrowths at the periphery of articular cartilage on joint margin
For where articular cartilage is worn, fibrillated and lost due to abnormal loading
Presence of osteophytes is a defining feature of osteoarthritis
Entheseophytes: what are they? Form where?Bony outgrowths
Form at attachments of tendons, ligaments, and joint capsules 2ry to inflammation/trauma
Osteoarthritis/osteoarthrosis/DJD = ?Slowly progressive disease of synovial joints
How are synovium & cartilage affected by DJD?Synovial effusion & cartilage degeneration
Etiology of DJDMay be 1ry aging change or 2ry to developmental disease, trauma, joint instability, epiphyseal aseptic necrosis, recurrent hemarthrosis, acquired abnormalities (e.g. after fracture or repair)
Most common locations for DJD in dogsCoxofemoral joints
Shoulder
Stifle
Radiographic signs of DJD(Initially normal)
Joint effusion
Osteophyte formation
Subchondral sclerosis
Cyst formation (advanced cases)
Intra-articular mineralization
Decreased ROM --> increased loading on weightbearing surface -->remodeling of subchondral bone
T/F Incidence of septic arthritis is higher than immune-mediated polyarthropathyFalse
Polyarticular septic arthritis usually 2ry to?Endocarditis
Omphalophlebitis
Discospondylitis
Complication of systemic illness e.g. Mycoplasma, Leishmaniasis, feline calicivirus
(Bacteriemia associated with isolated focus of infection)
Radiographic changes of septic arthritisJoint effusion & periarticular swelling --> joint cartilage destruction, subchondral and perichondral bone destruction if left untreated
Joint collapse
Osteomyelitis may ensue
Periarticular mineralized bodies can result from?Fractures, or result of infection/inflammation e.g. tendonitis
Differentials for periarticular mineralized bodiesChip fractures
Osteochondral fragments
Accessory centers of ossification
Mineralized cartilage, tendons, or synovia
(Don’t confuse sesamoid bones!)
Contributors to elbow dysplasia (3)Ununited anconeal process
Fragmented medal coronoid process
Osteochondrosis of medial humeral condyle
Contributors to hip dysplasia (2)Aseptic necrosis of femoral head (Legg-Calve-Perthes dz)
Patella luxation
What should you consider doing when radiographing patients with lameness/pain?Examination of contralateral limb/bone/joint
Dysplasia =Malformation. Inherited developmental disease (polygenetic trait), NOT CONGENITAL (joints are normal at birth!)
What factors play a role in dysplasia?Growth rate, nutrition, breed, etc.
Initial sign of dysplasia?Joint subluxation and instability
Dysplasia: subluxation leads to?Abnormal biomechanical stimuli, abnormal shape (e.g. shallow acetabulum)
Dysplasia: joint instability leads to?2ry DJD/osteoarthritis, remodeling of articular components (e.g. femoral head & neck, acetabulum, ulnar notch)
Early diagnosis of hip dysplasia is searching for what?Joint laxity (Dogs >6m.o.)
Hip dysplasia: What do you find on orthopedic examination? What do radiographs look like?Ortolani sign on palpation<rbr>Radiographs: VD extended limb projection with & without stress (distraction studies)
Hip dysplasia: early radiographic changes?Incongruent joint space
Center of femoral head isn’t within acetabulum (50% coverage)
Associated with joint laxity & minimal subluxation
Hip dysplasia: later radiographic changes?Chronic joint instability --> 2ry osteoarthritis/DJD
How does positioning of the pelvis affect assessment of coxofemoral laxity/sublux?Subluxation artificially increased if pelvis tilted closer to cassette, decreased if tilted away from cassette
Norberg angle is formed by?Line from the center of rotation of femoral heads to the cranial part of the acetabular ring
What is the Norberg angle in dogs? Cats?>105 dog, >95 cat
With increasing subluxation, the Norberg angle gets bigger/smaller?Smaller
Which cats are more commonly affected by hip dysplasia?Pure breed more than DSH
How does feline hip dysplasia differ from dogs?Degenerative changes appear later
Osteophytes mainly involve cranial acetabular limb
Acetabulum is more shallow (Norberg angle smaller)
Medial compartment disease = (3)(Syndrome)
Medial coronoid disease
Osteochondrosis of medial humeral condyle
Joint incongruity w/ articular cartilage disease
Breeds w/ high frequency of elbow dysplasia (6)Rottweiler
Bernese mountain dog
Saint Bernard
Golden retriever
German Shepherd
Labrador retriever
What projection do you add if suspecting fragmented medial coronoid process (medial FCP)?CrLCdMO (= CrCd with 15 degrees pronation)
Highlights cranio-medial aspect of elbow joint
Medial coronoid disease: radiographic changesTrochlear notch incongruous
MCP fails to develop, ossify (either stays united or fragments; cartilaginous), or does ossify with fissure/fragmented/malformed
2ry new bone formation
Which modality is better for medial coronoid disease?CT! Can visualize fragments, fissures, defects
Elbow dysplasia: what does ununited anconeal process (UAP) look like?Radiolucent zone in anconeal process
Modeling of anconeal process
Joint laxity- trochlear notch doesn’t form normally
New periarticular/perichondral bone production --> DJD
When should the anconeal process normally fuse?20-22 weeks
Recommended projection to show abnormalities of anconeal process? Why?Flexed mediolateral b/c avoids superimposition of humeral epicondyle on anconeal process
Luxated patella looks like?Abnormal position of patella
Superimposition with femoral condyles
(Projection for patellar luxation)Cranioproximal craniodistal skyline of stifles (bilateral medial luxation)
Inflammatory (poly)arthropathies: (8)Leishmaniasis
Rocky Mountain spotted fever
Rickettsia rickettsia
Lyme disease (Borrelia burgdorferi)
Mycoplasma
Chinese Shar-Pei fever syndrome
Feline calicivirus & coronavirus
Greyhound polyarthritis
Immune-mediated arthropathy in dogs =Rheumatoid arthritis (erosive)
What bones does rheumatoid arthritis usually affect?Distal extremities, sometimes stifle & elbow
Radiographic signs of rheumatoid arthritisInitially synovial effusion
Progressive subchondral bone destruction, cyst formation (weeks)
Joint space narrowing
Destruction of subchondral & perichondral bone --> collapse of epiphyses
Joint (sub)luxation
Feline immune-mediated polyarthropathy: who mostly affected?Males 1-5 years old
Types of immune-mediated polyarthritis in cats: (4)Feline periosteal proliferative arthritis (productive)
Erosive feline noninfectious polyarthritis (Rheumatoid-like)
Feline systemic lupus (non-erosive)
Feline idiopathic polyarthritis (non-erosive)
Feline rheumatoid-like arthritis: seen in who?Older cats
Feline rheumatoid-like arthritis: Radiographic changes?Severe subchondral bone erosion, cyst formation
Perichondral bone erosion
Bone destruction at points of ligament insertion
Subluxation of small joints of extremities
Feline rheumatoid-like arthritis: how to diagnose?Positive rheumatoid factor test and synovial biopsy (characteristic histological changes)
Feline periosteal proliferative arthritis: CS?Fever, malaise, stiffness --> periarticular soft tissue swelling, regional lymphadenopathy
Feline periosteal proliferative arthritis: radiographic changes?Periosteal new bone production at joint capsule attachments, entheseophyte formations, subchondral bone erosion, cyst formation
Perichondral erosion
Osteopenia of bone adjacent to affected joints
Narrowed joint spaces
(Other polyarthropathies of cats and dogs)((Hemarthrosis
Hypervitaminosis A
DJD
Disseminated idiopathic skeletal hyperostosis syndrome
Familial/genetic skeletal dysplasias
Drug-/vax-induced
Feline osteochondromatosis
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