Musculoskeletal & CT Disorders (Week 5) Flashcards Preview

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Family of disorders that affect primarily the joints of the axial skeleton. Highly associated with HLA-B27. Low back pain is the most common presenting symptom. They include Ankylosing spondylitis, Psoriatic arthritis, Reactive arthritis, and Enteropathic arthritis.


Ankylosing Spondylitis etiology + epidemiology

Most common spondylarthropathy. Ankylosis = abN stiffening and immobility of a joint from bone fusion. Associated w/HLA-B27, and m/b w/GI tract inflammation & elevated IgA to Klebsiella. More common in whites, onset teens-40 (rare after 50), Males 3:1


Anklosing Spondylitis SSx

Key on hx: insidious low back pain, sx before 40 yo, lasting >3mo, worse in AM & with inactivity, improvement with exercise.
General sx: fatigue, fever, wt loss
Muskuloskeletal: back pain unilateral, intermittent, begins at SI jt, becoming more severe, constant, and moving up the spine as dz worsens toward spinal fusion. AM stiffness at least 30 min. Erosion & ossification at ligament/tendon insertions (Achiles, plantar fascia, tibial tuberosity)
Other systems: eye pain, aortic valve insufficiency, restrictive lung dz from limited chest expansion, nerve root compression can cause radiculopathy or cauda equina syndrome.


Ankylosing Spondylitis PE

Joints TTP (especially SI), decreased active & passive ROM (esp. lumbar), red eyes with photophobia.


Ankylosing Spondylitis Labs

No labs are diagnostic. M/b anemia on CBC, HLA-B27 positive, RF + ANA negative.


Ankylosing Spondylitis Imaging

*Must have SI involvement for dx. Plain radiograph shows bony erosions + sclerosis of SI joint. Spine x-ray has ossification leading to "bamboo spine." Peripheral joints may show joint space narrowing & ankylosis. MRI & CT not used, expensive.


Ankylosing Spondylitis Progrnosis

Progressive, spinal fusion, thoracic kyphosis, erosive dz. Most pts remain fully functional.


Psoriatic Arthritis etiology & epidemiology

Occurs in ~1/3 pts with Psoriasis, especially with nail involvement. Has significant involvement of peripheral joints. ~40% have a first degree relative with it, s/t HLA-B27. Etiology unknown. Mostly whites 35-55yo.


Psoriatic Arthritis SSx

Onset insidious. Often preceded by psoriasis, especially w/nail lesions. S/t stiffness & pain. Arthritis can be asymmetrical oligoarthritis or symmetric polyarthritis. Affected joints tender, warm, restricted ROM. Hands - "sausage digits" DIP involvement, atrhritis mutilans (destruction of joints, telescoping digits). Any joint can be involved, m/b back pain, enthesitis (inflammation of tendon-bone connection) at Achilles or plantar fascia. M/b eye involvement.


Psoriatic Arthritis Labs

ESR, CRP, and serum IgA often elevated. Uric acid may be high from cell turnover in psoriasis. Synovial fluid is inflammatory, w/high WBC


Psoriatic Arthritis Radiography

Erosion & bone growth. "Pencil in cup" deformity, bony bridges through spine.


*Psoriatic Arthritis Diagnostic Criteria*

Inflammatory articular dx with at least 3 pts of:
-Current psoriasis (2)
-Hx of psoriasis in absence of current psoriasis (1)
-Family hx of psoriasis in absence of personal hx (1)
-Dactylitis/sausage fingers (1)
-Juxta-articular new-bone formation (1)
-RF negativity (1)
-Nail dystrophy (1)


Psoriatic Arthritis Prognosis

~40% develop deforming arthritis. M/b increased risk of HTN, obesity, hyperlipidemia, DM, cardiovascular dz.


Reactive Arthritis etiology + epidemiology

Arises after an infection of GU, GI, or Chlamydia. Classic triad (only seen in 1/3 of pts): urethritis, arthritis, conjunctivitis ("can't see, can't pee, can't climb a tree!") Genetic link to HLA-B27. Common in context of HIV infection. Most common in young men, peak onset in 20's (especially more common in men if following a venereal infection instead of the other ones). White ppl.


Reactive Arthritis SSx

Acute, devel. 2-4 wks after infection. General: malaise, fatigue, fever. Skin: hyperkeratotic skin starting as clear vesicles, macules, papules, and then nodules. Oral erythema, erosion, bleeding. Eyes: inflammation, any "itis". MS: asymmetrical oligoarthritis w/pain & stiffness, mostly LOWER EXTREMITies. Low back pain & SI involvement (decreased lumbar flexion), Heel pain w/achilles enthesitis & plantar fasciitis. GI: prolonged bloody diarrhea. GU: Urethritis, frequency, dysuria, urgency, urethral discharge, prostatitis, volvovaginitis, circinate balanitis (shallow painless ulcers). M/b aortic regurge.


Reactive Arthritis Labs

M/b anemia on CBC, elevated ESR/CRP, RF & ANA negative. M/b infection of cervix/urethra. M/b HLA-B27 positive. WBC, RBC, and protein in urine. Synovial fluid has high WBC, negative gram stain & culture.


Reactive Arthritis Imaging

Radiograph of the pelvis looks like Ankylosing Spondylitis. Otherwise early dz shows no abnormalities, while more advanced disease may show proliferation at tendon insertions & erosion/proliferation in hands & feet.


Reactive Arthritis Prognosis

Self limited, usu resolving in 3-12 months. HLA-B27 may predict longer course + more severe dz. ~50% develop long-term arthritis, enthesitis, or spondylitis.


Enteropathic Spondylarthritis

Asymmetric, non-erosive peripheral arthritis in pts with IBD, that corresponds with IBD activity. More common in Crohn's that UC. 10-30% of IBD pts, may precede GI sxs. Dactylitis + enthesitis m/b present. (Note, in advanced cases it may look symmetric purely by virtue of the number of joints involved.)


Crystal-Induced Arthritis

Intra-articular deposition of crystals causing inflammatory arthritis. Gout & Pseudogout are most common. Diagnosis requires synovial fluid analysis by polarized light microscopy.



Metabolic disorder allowing uric acid to accumulate in blood & tissues. Recurrent episodes of pain, can lead to joint destruction & renal damage. Flares often triggered by acute changes in urate.


Gout Etiology + Epidemiology

Primary - genetic, high incidence of comorbidity with HTN, DM, renal insufficiency, hypercholesterolemia, obesity, and anemia.
Secondary - Over production of uric acid from dz with high cell turnover. E.g. psoriasis, hemolytic anemias, myeloproliferative + lymphoproliferative disorders. More common in males 3:1, male onset is 30-60, female onset 60-80 (after menopause).


Gout SSx

Sodden onset intense monoarticular pain. 50% start in MP joint of big toe (AKA podagra), also common in instep, ankle, wrist, fingers, knee. Joints red, hot, tender. Most attacks resolve in 2 weeks. Can become more polyarticular and longer lasting, even developing chronic arthritis that resembles RA. Tophi may develop (urate crystals in soft tissue). Increased risk of renal stones.


Gout Dx

Serum uric acid high in 95%, WBC elevated, ESR elevated during attack. Synovial fluid tested to r/o infectious arthritis & confirm gout (can co-exist), needle-shaped monosodium urate crystals intra+extracellularly, WBC count usu. high (10,000-100,000). Radiographs may show characteristic punched-out erosions or lytic areas w/overhanging edges. Haziness suggests tophi, they may calcify, joing space usu maintained.


Pseudogout (Calcium pyrophosphate deposition disease/CPPD)

Gout but with calcium pyrophosphate crystals. Affects large joints (knee, wrist, ankle, elbow), onset rapid or insidious. Often idiopathic, but m/b associated w/anything that leads to osteoarthritis. Risk Factors: genetics, advanced age, loop diuretics, proton pump inhibitors. Calcium phosphate crystals on joint aspiration. Imaging shows degeneration, m/b soft tissue calcification. Work up includes chemistry screen, serum magnesium, calcium, iron, + thyroid function tests.


Infectious Arthritis

Can be infected by anything, most commonly bacteria. Infection directly, spreading from adjacent tissue, or through bloodstream. Previously damaged joints are most susceptible *keep in mind for patients with pre-existing joint dz (gout, RA, etc.)


Arthritis due to Bacterial Infection

Damage to articular cartilage can occur w/in days of infection. S. aureus is most common pathogen, N. gonorrhoea peaks in young sexually active adults.


Arthritis due to Bacterial Infection - Risk Factors

Previous joint dz, prosthetic joints/joint surgery, IV drug use, alcoholism, immunosuppression/deficiency, diabetes, old age, unprotected sex


Arthritis due to Bacterial Infection - SSx

Onset over a few days (prosthetic joints progress more slowly w/gradual increase in pain.) General: low grade fever. Joints: pain, redness, swelling, reduced ROM. Mono or polyarticular. Knee is most common joint, then hip, shoulder, ankle, and wrist. If gonococcal in origin, multiple skin lesions start papular, then pustular or vesicular then necrotic.


Arthritis due to Bacterial Infection - Diagnosis

Joint fluid m/b yellow/green, WBCs high (mostly PMNs), culture is THE DEFINITIVE METHOD for diagnosing. If gonococcal infection suspected then culture relevant areas (cervix, urethra, pharynx, etc.)