8. Arthritis Flashcards
Although there are over 90 different rheumatic diseases recognized by the American College of Rheumatology, only a few tend to show up on multiple choice tests (and at the view box).
You can broadly categorize arthritis into 3 categories:
- Degenerative (OA, Neuropathic)
- Inflammatory (RA and Variants)
- Metabolic (Gout, CPPD)
Degenerative Arthritis
Osteoarthritis
Neuropathic Joint
Osteoarthritis
MOST common cause of Degenerative Arthritis
mechanical breakdown (hard work) which leads to cartilage degeneration (fissures, micro-fractures) and fragmentation of subchondral bone (sclerosis and subchondral cysts).
Osteoarthritis
You get all the classic stuff, joint space narrowing (NOT svmmetric). subchondral cysts, endplate changes, vacuum phenomenon, etc…
The poster boy is the osteophyte.
Charcot Foot
“rocker-bottom deformity”
deformity, with debris, and dislocation, having dense subchondral bone, and destruction o f the articular cortex
Erosive Osteoarthritis (Inflammatory Osteoarthritis)
The buzzword is “gull wing”, which describes the central erosions. It is seen in postmenopausal women and favors the DIP joints.
Rheumatoid Arthritis
osteoporosis, soft tissue swelling, marginal erosions and uniform joint space narrowing
It’s often bilateral and symmetric. Classically spares the DIP joints (opposite of erosive OA).
The 5th Metatarsal head is the first spot in the foot
Expect the PIP joints to be involved AFTER the MCP joints.
RA > 10 years + Splenomegaly + Neutropenia
Felty Syndrome
RA + Pneumoconiosis
Caplan Syndrome
The distribution of RA vs OA in the hip is a classic teaching point:
Rheumatoid Variants:
Psoriatic Arthritis
Reiter’s syndrome (Reactive arthritis)
Ankylosing Spondylitis
Inflammatory Bowel Disease
Psoriatic Arthritis:
This is seen in 30% ofpatients with psoriasis. In almost all cases (90%) the skin findings come first, then you get the arthritis.
“erosive change with bone proliferation (IP joints > MCP joints)”
The erosions start in the margins of the joint and progress to involve the central portions (can lead to a “pencil sharpening” effect).
Psoriatic Arthritis Buzzwords
When I say Ankylosis in the Hand, You Say =
You Say (1) Erosive OA or (2) Psoriasis
RA vs Psoriasis
Mutilans
Reiter’s (Reactive Arthritis)
a very similar situation to Psoriatic arthritis - both have bone proliferation, erosions, and asymmetric SI joint involvement.
The difference is that Reiter’s is RARE in the hands (tends to affect the feet more).
ust remember Reiter’s favors things below the waist (like the penis = urethritis, and the foot).
Reiter’s Triad
Urethritis
Conjunctivitis
Arthritis
(Can’t See or Climb a Tree to Pee on a Nazi named Reiter).
Psoriatic and Reactive arthritis are both associated
HLA-B27
Ankylosing Spondylitis
This disease favors the spine and SI joints
“bamboo spine”
SI joint involvement is usually the first site (symmetric)
Ankylosing Spondylitis:
“bamboo spine”
syndesmophytes flowing from adjacent vertebral bodies.
Any significant Ank Spon / DISH + Even Minor Trauma =
Whole Spine CT
When the peripheral skeleton is involved in patient’s with Ank Spond =
think about the shoulders and hips (hips more common). Hip involvement can be very disabling.
If they show you normal SI joints then show you anything in the spine =
it’s not Ankylosisng spondylitis
It has to hit the SI joints first (especially on multiple choice).
inflammatory Bowel Disease (Enteropathic)
Allegedly 20% of patient’s with Crohns & UC have a chronic inflammatory arthritis. The imaging findings occurs in two distinct flavors.
(A): Axial Arthritis (favors SI joints and spine) - often unrelated to bowel disease
(B): Peripheral Arthritis - this one varies depending on the severity of the bowel disease.
SI Joint Involvement Patterns (Rheumatoid Variants)
Metabolic arthtritis =
Gout
CPPD
Hemochromatosis
Hyperparathyroidism
Gouty Arthritis
Earliest Sign = Joint Effusion
Spares the Joint Space (until late in the disease); Juxta- articular Erosions - away from the joint.
“Punched out lytic lesions”
“Overhanging Edges”
Soft tissue tophi
Gout Mimickers:
There are 5 entities that can give a similar appearance to a gouty arthritis, although they are much less common. This is the mnemonic I was taught in training:
“American Roentgen Ray Society Hooray”
Amyloid
RA (cystic)
Reticular Histocytosis (the most rare)
Sarcoid
Hyperlipidemia
CPPD
Calcium Pyrophosphate Dihydrate Disease
is super common in old people
It often causes chondocalcinosis (although there are other causes)
CPPD loves the triangular fibrocartilage of the wrist, the peri-odontoid tissue, and intervertebral disks.
“degenerative change in an uncommon joint”
Hooked MCP Osteophytes with chondrocalcinosis in the TFCC is a classic look (although hemochromatosis can also look that way).
Synovitis + CPPD =
Pseudogout
pyrophosphate arthropathy is most common at the?
knee
Ifyou see isolateddisease in thepatellofemoral, radiocarpal, or talonavicularjoint, think
CPPD
OA vs CPPD ?
There are many overlapping features including joint space narrowing, subchondral sclerosis, subchondral cyst, and osteophyte formation
CPPD has some unique features such as =
“atypical joint distribution”
favoring compartments like the patellofemoral or radiocarpal. Subchondral cyst formation can be bigger than expected.
Hemochromatosis
iron overload disease also is known for calcium pyrophosphate deposition and resulting chondrocalcinosis.
It has a similar distribution to CPPD (MCP joints). Both CPPD and Hemochromatosis will have “hooked osteophytes” at the MCP joint.
CPPD vs Hemochromatosis:
Hemochromatosis has uniform joint space loss at ALL the MCP joints.
CPPD favors the index and middle finger MCPs.
As a point of trivia, therapy for the systemic disease does NOT affect the arthritis.
‘‘Milwaukee Shoulder”
This is an apocalyptic destruction of the shoulder (almost looks neuropathic) secondary to the demon mineral hydroxyapatite.
Classic History: Old women with a history of trauma to that joint.
Hyperparathyroidism
this can be primary or secondary, and its effects on calcium metabolism typically manifest in the bones.
“Subperiosteal bone resorption”
Hyperparathyroidism
Hyperparathyroidism
The classic ways this can be shown:
Superior and inferior rib notching - bone resorption
Resorption along the radial aspect o f thefingers with brown tumors
Tuft Resorption
Rugger Jersey Spine
Pelvis with Narrowing or “Constricting”ofthefemoral necks, and wide SI joints.
Fuckery: They can show you any of these classic pictures and then want you to say “Phosphate Retention” is the cause (Hyper PTH causes phosphate retention)
