1 Flashcards
Rheumatoid Arthritis – chronic multisystem disease of unknown origin
RA is the Gold Standard of inflammatory arthritis
Polyarthritis – involves more than one joint
o Foot is almost always involved
Inflammation in the synovium – causing a synovial pannus
Epidemiology of RA
Worldwide
Occurs in 1% of US adults
3:1 female:male
Peak age = 35-45 yrs (incidence increases w/ age
Pathogenesis of RA
1) mutation predisposes someone to
o 90% have HLA-DR4 gene
o A response to a synovial autoantigen
Pathogenesis of RA
2) cytokines perpetuate synovial inflammation causing T-cells to respond
o CD4 T-cells – play primary role in RA inflammation TH1 CD4 – implicate chronic inflammation
o Examples of cytokines
TNFα – key player in synovial inflammation; controls production of collage proteinases
Pathogenesis of RA
3) autoantibodies, specific for the Fc Fragment of IgG of synovium, can be found and used as diagnosis
o RF – seen in 85% of RA; major lab hallmark of RA
associated w/ severe disease
o Anti-CCP – autoantibodies to cyclic citrullinated peptides; have high specificity in identifying pts prone to irreversible damage, but a negative result does not rule out disease
Appear early in disease – pre-clinical stage of joint destruction
Levels skyrocket before RA diagnosis
o +RF plus +CCP = RA w/ 30-40% sensitivity and 98-100% specificity
Pathogenesis of RA
4) inflammation continues to form an invasive, hyperplastic synovial membrane (pannus)
o Synovial Pannus – mass of chronic inflammatory granulation tissue that destroys joints by
eroding and attack soft tissue
Morphology of RA
1) Synovial Phase – buildup of synovial fluid
o Joint space widening
o Joint is swollen and cool
2) Periarticular Phase – soft tissue swelling and beginning of pannus formation
o Pannus covers joint surfaces
3) Erosion – erosion into bone begins at intra-articular bare areas
4) Chondrolysis – cartilage loss begins causing joint space narrowing
5) Erosions continue into subchondral cortex
6) End Stage – fibrous ankylosis (fusion of joint)
Systemic Manifestations of RA – RA is systemic
Skin – RA nodules in 50%
Ocular – keratoconjunctivitis sicca
Cardiac – pericardial effusions
Pulmonary – interstitial fibrosis and nodules
Hematologic – hypochromic/microcytic anemia and vasculitis
Neurologic – tarsal tunnel syndrome, Cervical spine instability
Systemic Manifestations of RA – RA is systemic
Associated ds
o Fatigue
o Morningstiffness o Nodules
o Vasculitis, Scleritis
o Sjogren’s Syndrome o Lymphadenopathy
o Peripheral neuropathy o Pleuritis
o Interstitial lung fibrosis, Pericarditis
o Amyloidosis, Splenomegaly, Felty’s Syndrome
Diagnostic Criteria for RA – need 4 for diagnosis
Morning stiffness > 1hr
Arthritis in > 3 joints – simultaneous w/ fluid
Arthritic hand joints – at least one joint
Symmetric Arthritis – bilateral
Rheumatoid Nodules – non-calcified subQ nodules over bony prominences, extensor surfaces, etc.
Serum RF – seen in 85%
Radiographic findings in AP hand and wrist
Pedal Involvement of RA
1:10 have onset of RA w/ pedal joint attack preceding hands
Clinical Syndromes:
o Severe Hallux Valgus (w/ or w/o bunion)
o Flatfoot & hyperpronation
Decreased calcaneal inclination
Vertical talus
o Depression of met heads w/ or w/o atrophy of plantar fat pad
Anterior migration of fat pad w/ increased pressure on met heads (metatarsalga)
o Retrocalcaneal bursitits
o Tarsal Tunnel syndrome – plantar “burning” paresthesia
Pedal Involvement of RA
90% of RA has pedal involvement
Foot is initial presentation of RA in 1:10 (preceding hands; 10-20%)
Pedal Locations of RA o MPJ’s and IPJ
Most common – 5th MPJ
2nd most common – medial 1st IPJ (over 50% of cases)
Not common in PIP’s and DIP’s
o Chopart’s joint (TN) – seen in 40% o Lisfranc’s Joint – seen in 36%
o Posterior Facet of STJ – seen in 29% o Cuneiform Joints – seen in 28%
o CC Joint – seen in 25%
o STJ and Ankle joint – not as common
Early RA Radiographs
Soft Tissue Swelling – usually lateral 5th MPJ
Periarticular Osteopenia/Osteoporosis
o Gray tone parity – the tons on the inside of the bone are the same as those outside the bone of the soft tissues
Early RA Radiographs
Concentric Joint Space Narrowing – due to irreversible cartilage loss o Chondrolysis – a response to pannus extension across a joint
Concentric cartilage loss
Early RA finding – can happen in wks/months
Occurs before bone erosions – allows an earlier diagnosis *note – in Robust RA, you’re less likely to have joint space
narrowing (spares the joint space)
Early RA Radiographs
Small Marginal “Bare Area” Erosions
o Pannus attacks osseous margins w/in joint that aren’t protected by cartilage (bare areas)
o Seen as cookie-cutter notches out of met heads
*remember, met heads are usually convex w/ a lateral fovea concavity (don’t confuse normal fovea w/ concavity). If it’s seen on the medial side, it’s definitely an erosion
Early RA Radiographs
Small Marginal “Bare Area” Erosions
o Characteristics of RA Erosions
(on the mets not phalanges) Phalangeal involvement means late RA
“En Face” erosions are common – ones that face eachother o Target sites
Small,
Early RA Radiographs
Small Marginal “Bare Area” Erosions
o Target sites
Medial and Lateral 5th met head
Medial lesser met heads
Medial 1st IP joint
Sesamoids
Early RA Radiographs
Subchondral Cyst Formation
o Subchondral Cyst – transtentorial extension of superficial pannus and direct
extension of subchondral pannus into bone
Advanced RA Radiographs – positional deformities indicate advanced disease
Synovial-lined Bursa – causes erosive bursitis
o Bywater’s Lesions – erosive changes around the retrocalcaneal bursa
show a gun barrel sign
Chronic Tenosynovitis – atrophy, entrapment, weakening, contracture, rupture of tendons
o Tendon rupture – can lead to Post. Tib. Tendon Disorder & flatfoot
o Can cause inflammation & scarring in the tarsal tunnel, causing tarsal tunnel syndrome
Advanced RA Radiographs – positional deformities indicate advanced disease
Ligamentous Atrophy – causes joint laxity
Intrinsic Muscle Atrophy – leads to severe digital subluxations
o Leads to…
Fibular drift – lateral deviation/subluxation of the phalanges on the mets Hammertoes/contracted digits
Plantar met head prominence (mentioned before)
Splayfoot – totally subluxation of all phalanges
HAV (rarely hallux varus)
Progressive Radiographic Features of RA
Osseous Islands – involving the 5th met (sometimes 1st)
o Pannus that covers bone on met head erodes bone and forms an island
o Starts out as just pannus formation and progresses to formation of island
Progressive Radiographic Features of RA
Severe Generalized Osteoporosis – significant gray tone parity
Arthritis Mutilans – severe derangement of joints
Ankylosis - RA’s endpoint is fibrous ankylosis
o Mortar and Pestle Deformity – the proximal phalange completely surrounds the met head
o Fibrous ankylosis seen only in forefoot (not midfoot or rearfoot)
Insufficiency/Spontaneous Functions – due to osteoporosis
Midfoot/Rearfoot/LE Radiographs of RA
Concentric Chondrolysis w/ secondary OA – seen in TN, STJ, and lateral column
Symmetric subchondral cysts
Midfoot/Rearfoot/LE Radiographs of RA
Heel Lesions
o Locations
Site 1&2 – retrocalcaneal bursa/recess
Site 3 – Achilles tendon insertion
Site 4 – plantar fascia attachment 6
Site 5 – long plantar ligament attachment
Site 6 – short plantar ligament attachment
Midfoot/Rearfoot/LE Radiographs of RA
Types
Retrocalcaneal Bursitis (Bywater’s lesions) – small well-defined osseous changes 1&2 Achilles Tendon Inflammation – at site 3
Small enthesophytes – at sites 3 or 4
Subcutaneous peritendinous nodules
Midfoot/Rearfoot/LE Radiographs of RA
Distal Fibular Notch – site of notching or scalloping o seen in 43% of RA ankles
o Occurs at the distal tibfib syndesmosis
75% occur at the syndesmotic folding 25% occur below talar dome
o Can be 7-23mm large
o Associated w/ coexistent joint narrowing and marginal erosions
Midfoot/Rearfoot/LE Radiographs of RA
Things uncommonly seen in Rearfoot RA:
o Marginal erosions are uncommon in rearfoot – so no little knicks out of the bone o Boney ankylosis isn’t common
Boney ankylosis usually happens distal to Lisfranc’s Joint (metatarsals and phalanges)
Complications of RA
Secondary OA – due to walking on malformed joints after RA changes (wear and tear OA)
Stress Fractures – due to osteopenic insufficiency
o Usually seen in mets and calcaneus
Common Arthopathies:
Rheumatoid Arthritis
Seronegative Arthritis
Osteoarthritis
Gouty Arthritis
Neuroarthropathy
CPPD/HAD
DISH
