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MSK I: Arthritis/Rheum Cheat Sheet by



Progre­ssive loss of articular cartilage with reactive changes in the bone, results in pain and joint destru­ction (most common arthro­pathy in adults)
Clinical Features
Decreased ROM, joint crepitus, pain worsening througout the day
Common sites
DIP joint (Heber­den's nodes + PIP joint (Bouch­ard's nodes), and wrist/­hip­/kn­ee/­spine
Asymmetric narrowing or joint spaces, subcho­ndral sclerosis, cysts, marginal osteop­hytes
Weight reduction, physical actibity, acetam­ino­phen, NSAIDs, intra-­art­icular steroids. Total joint replac­ement in advanced cases.

Rheumatoid Arthritis

A chronic autoimmune disease with synovitis affecting multiple joints and other systemic extra-­art­icular manife­sta­tions. Joint destru­ction ultimately occurs.
Typical patient
F>>M, 40-60yo at onset (juvenile in pts <16yo)
Clinical Features
Morning stiffness, symmetric, subcut­aneous nodules, RF level >95th percen­tile, arthritis of hand joints, soft-t­issue swelling (DIP joints spared)
Extra-­art­icular manife­sta­tions
Osteop­orosis, changes in skin/l­ung­s/k­idn­eys­/ey­es/­liv­er/­blo­ods­tre­am/­heart
Lab Studies
Elevated ESR + CRP, RF and anti-CCP positive in up to 80%
PT + NSAIDS + DMARDS (MTX, cortic­ost­eroids, biologics) and recons­tru­ctive surgery for severe cases.


A systemic disease of altered purine metabolism and subsequent sodium urate crystal precip­itation into synovial fluid
Typical patient
M>>W (until menopause, then 1:1)
Clinical Features of Initial Attack
Metatarsal phalangeal joint of the great toe (podagra)
Symptoms around involved joint
Pain, swelling, redness, exquisite tenderness
Substance that may form adjacent to the joint, diagno­stic!
Tophi (chalky deposits of uric acid)
Lab Studies
Joint fluid shows rod-sh­aped, negatively birefr­ingent urate crystals seen. Serum uric acid level often > 8 mg/dL
Lifestyle Modifi­cations
Elevation, dietary modifi­cations (avoid purines and EtOH)
NSAIDs (indom­eth­acin), cortic­ost­eroid inject­ions, colchicine in between attacks

Polymy­algia Rheumatica (PMR)

Syndrome with pain and stiffness in the neck/s­hou­lde­r/p­elvic girdles and is accomp­anied by consti­tut­ional symptoms (fever, fatigue, weight loss, depres­sion)
Unknown (F>­>M)
Associated with
Temporal arteritis (30% of cases)
Clinical features
Stiffness, worse after rest and in the morning. MSK symptoms are bilateral, proximal, symmet­rical
Must r/o...
Giant Cell Arteritis (scalp tender­ness, jaw claudi­cation, headache, temporal artery tender­nes­s--­>can lead to vision loss)
Lab Studies
ESR elevated (>5­0mm/hr)
Low-dose cortic­ost­eroids (higher doses if GCA), might need to be on for 2 years

Sjogren's Syndrome

An autoimmune disease that destroys the salivary and lacrimal glands (exocrine glands)
May be a secondary compli­cation to pre-ex­isting disorders like...
RA, SKE, polymy­ositis, sclero­derma
Classic Patient
Middle­-aged females
Clinical Features
Mucus membranes most affected. Parotid glands might be enlarged.
Charac­ter­istic features of primary Sjogren's
Dry mouth (xeros­tomia) + dry eyes (serop­thalmia or kerato­con­jun­cti­vitis)
Lab Studies
RF in 70% of cases, ANA in 60%, anti-Ro Abs in 60%, anti-La in 40%. Schirmer's tear test wetting of <5mm of filter paper in lower eyelid in 5min = + for decreased secretions
How to confirm lympho­cytic infiltrate and gland fibrosis
Lip bx
Mainly sympto­matic manage­ment, goal of keeping mycosal surfaces moist. Can give artificial tears and saliva, increased oral fluid intake, and lubricants for eyes/v­agina. Piloca­rpine may increase saliva flow

Childh­ood­-onset idiopathic arthritis

Charac­terized by chronic synovitis and extra-­art­icular manife­sta­tions (fever, rash, weight loss)
Typical Patient
F>>M, at age 1-3yo (males older 8-12yo)
Forms of arthritis
Paucia­rti­cular (50%) polyar­ticular (35%), systemic (15%)
Systemic (JRA) clinical features
Spiking fevers, myalgias, salmon­-pink maculo­papular rashin evening. Hepato­spl­eno­megaly, lympha­den­opathy, leukoc­ytosis, perica­rditis, myocar­ditis
Paucia­rti­cular clinical features
4 or less medium to large joints. Also at risk for asympt­ommatic uveitis (can lead to blindness if +ANA)
Polyar­ticular clinical features
Resembles adult RA, symmetri, 5+ joints. Systemic sx: low-grade fever, fatigue, rheumatoid nodules, anemia.

Psoriatic Arthritis

An inflam­matory arthritis with skin involv­ement usually preceding joint disease
Clinical features
Symmetric, hands and feet. Affects few joints. Pitting of nails and onycho­lysis. "­Sau­sag­e-f­ing­er" appearance
Lab Studies
ESR elevated, hyperu­ricemia if severe skin involv­ement, "­pencil in a cup" deformity on x-ray
NSAIDs, MTX, recons­tru­ctive surgery as last resort


Intra-­art­icular deposition of calcium pyroph­osphate dehydrate (CPPD) in peripheral joints
Acute presen­tations mimic...
Gout (may be recurrent and abrubt)
Clinical features
Painful inflam­mation (when crystals shed into joint), most common in knees/­wri­st/­elbow
Lab Studies
Rhombo­id-­shaped CPPD crystals, negatively birefr­ing­ement. Will see chondr­oca­lci­nosis in radiog­raphs (fine, linear calcif­ica­tions)
NSAIDS, colchi­cine, and intra-­art­icular steroid injections


An inflam­matory disease of striated muscle affecting the proximal limbs/­nec­k/p­harynx (skin can also be affect­ed=­der­mat­omy­ositis)
Unknown, but strong associ­ation with occult malignancy
Classic patient
Clinical Features
Insidious painless proximal muscle weakness, dysphagia, skin rash (malar or heliot­rope), polyar­thr­algias, muscle atrophy
Lab Studies
CPK and aldolase elevated. Muscle bx will show myopathic inflam­matory changes
High-dose steroids, MTX, or azathi­oprine

Sclero­derma (Systemic Sclerosis)

Charac­terized by deposition of collagen in the skin, and also lungs, kidney, heart stomach. Unknown etiology.
Classic Patient
F>>M, 30-50yo
Clinical Features in general
95% of patients have skin involv­ement, starts with swelling of fingers and hands, may spread to trunk and face. R
Clinical Features: Limited
Mostly affects skin of face, neck, distal elbows and knees. Causes pulmonary hypert­ension later in disease.
Clinical Features: Diffuse
Affects the skin plus the heart, lungs, GI tract, kidneys
CREST Syndrome (assoc­iated with limited sclero­derma
Calcin­osis, Raynaud's, esophageal dysfun­ction, sclero­dac­tyly, telang­iec­tasias
Initial presen­tation
Skin changes, polyar­thr­algias, esophageal dysfun­ction
Lab Studies
+ANA in 90% of pts, +antic­ent­romere Ab assoc. w/ limited sclero­derma, watch for HTN
No cure. Treat specific manife­sta­tions of disease (ie PPIs for GERD, ACEis for renal dz, aboid triggers, and immuno­sup­pre­ssives for pulmonary HTN)

Septic (Infec­tious) Arthritis

The hemato­genous spread of bacteremia infection (osteo­mye­litis) caused by diagnostic or therap­eutic procedure (injec­tion) or infection elsewhere (cellu­litis, bursitis)
Classic joint
Single joint, usually knee (can also be hip, shoulder, ankle)
Most common pathogen
Staph. aureus
Pathogen in sexual­ly-­active young adults
Neisseria gonorrhea
Clinical Presen­tation
Acute swelling, fever, joint warmth and effusion, tenderness to palpation, increased pain w/ minimal ROM
Lab Studies
Collec­t/a­spirate synovial fluid, many will also have a positive blood culture.
Aggressive IV Abx followed by oral antibi­otics, sometimes arthrotomy and arthro­cen­tesis are required.

Reactive Arthritis (Reiter Syndrome)

A serone­gative arthritis that has a tetrad of: urethr­itis, conjun­cti­vitis, oligoa­rth­ritis, and mucosal ulcers (leading cause of nontra­umatic monoar­thr­itis)
Can be seen as a sequele to...
STDs or gastro­ent­eritis
Clinical Features
Asymmetric arthritis in large joints below the waist (knee, ankle), mucocu­taneous lesions (balan­itis, stomat­itis), urethr­itis, conjun­cti­vitis
Typical patient
M>>F after STDs (1:1 ratio after enteric infx)
Lab Studies
Up to 80% HLA-B27+, synovial fluid negative culture
PT + NSAIDs. Abx can reduce chance of developing disorder, but they don't alleviate sx of the reactive arthritis

SLE (Systemic Lupus Erythe­matous)

An autoimmune disorder charac­terized by inflam­mation, plus +ANA, and involv­ement of multiple organs
Classic Patient
Women of childb­earing age, and more in Africa­n-A­merican women
Clinical Features
(4+ criteria including high ANA): malar rash, discoid rash, photos­ens­iti­vity, oral ulcers, arthritis, serositis, renal dz, ANA, hemato­log­ic/­imm­uno­log­ic/­neu­rologic disorders
What must be ruled out?
Drug-i­nduced lupus/­lup­us-like syndrome (from INH, hydral­azine, quinid­ine). Usually pt. will have positive antihi­stone Abs
Lab Studies
Get CBC BUN, Cr, U/A, ESR, serum complement (C3 or C4), anti-Smith antibodies to mark for progre­ssion. ANA is present 99% of the time, but low titers have a low predictive value.
Exercise + sun protec­tion, NSAIDs, Antima­larials (hydro­xyc­hlo­roq­uine), cortic­ost­eroids, MTX

Polyar­teritis Nodosa

Small/­medium artery inflam­mation involving the skin, kidney, peripheral nerves, muscles, and gut
Classic patient
M>>F, 40-60yo, Hep B pts
Unknown (concu­rrent in Hep B pts. 30% of the time)
Clinical Features
Fever, anorexia, weight loss, abdominal pain, peripheral neurop­athy, arthra­lgias, arthritis, skin lesions. If renal involv­ement: HTN, edema, oliguria, uremia (if renal involv­ement.
Lab Studies
Vessel bx or angiog­raphy to diagnose (might also see ANCA, elevated ESR and CRP)
High-dose cortic­ost­eroids, cytotoxic drugs, immuno­the­rapy. Might need to also treat for Hep B. Treat HTN if present

Fibrom­yalgia Syndrome

A central pain disorder; cause and pathog­enesis are poorly understood
Can occur concur­rently with...
RA, SLE, Sjogren's
Clinicla Features
Nonart­icular MSK aches, fatigue, sleep distur­bance, multiple tender points on exam, anxiety, depres­sion, headaches, irritable bowel syndrome, dysmen­orrhea, parest­hesias
Lab Studies
Diagnosis of exclusion, must r/o hormonal and vitamin distur­bances. Sometimes abnorm­alities of T-cell subsets
SSRIs, SSNRIs, RCAs. Lyrica is only FDA-ap­proved drug to specif­ically treat fibrom­yalgia. Aerobic exercise, stress reduction, and sleep assistance are helpful.

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