Musculoskeletal & CT Disorders (Week 5)

Question 1

Spondylarthropathies

Answer 1

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.

Question 2

Ankylosing Spondylitis etiology + epidemiology

Answer 2

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

Question 3

Anklosing Spondylitis SSx

Answer 3

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.

Question 4

Ankylosing Spondylitis PE

Answer 4

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

Question 5

Ankylosing Spondylitis Labs

Answer 5

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

Question 6

Ankylosing Spondylitis Imaging

Answer 6

*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.

Question 7

Ankylosing Spondylitis Progrnosis

Answer 7

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

Question 8

Psoriatic Arthritis etiology & epidemiology

Answer 8

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.

Question 9

Psoriatic Arthritis SSx

Answer 9

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.

Question 10

Psoriatic Arthritis Labs

Answer 10

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

Question 11

Psoriatic Arthritis Radiography

Answer 11

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

Question 12

Psoriatic Arthritis Diagnostic Criteria

Answer 12

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)

Question 13

Psoriatic Arthritis Prognosis

Answer 13

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

Question 14

Reactive Arthritis etiology + epidemiology

Answer 14

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.

Question 15

Reactive Arthritis SSx

Answer 15

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.

Question 16

Reactive Arthritis Labs

Answer 16

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.

Question 17

Reactive Arthritis Imaging

Answer 17

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.

Question 18

Reactive Arthritis Prognosis

Answer 18

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.

Question 19

Enteropathic Spondylarthritis

Answer 19

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.)

Question 20

Crystal-Induced Arthritis

Answer 20

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

Question 21

Gout

Answer 21

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.

Question 22

Gout Etiology + Epidemiology

Answer 22

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).

Question 23

Gout SSx

Answer 23

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.

Question 24

Gout Dx

Answer 24

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.

Question 25

Pseudogout (Calcium pyrophosphate deposition disease/CPPD)

Answer 25

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.

Question 26

Infectious Arthritis

Answer 26

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.)

Question 27

Arthritis due to Bacterial Infection

Answer 27

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.

Question 28

Arthritis due to Bacterial Infection - Risk Factors

Answer 28

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

Question 29

Arthritis due to Bacterial Infection - SSx

Answer 29

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.

Question 30

Arthritis due to Bacterial Infection - Diagnosis

Answer 30

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.)

Question 31

Arthritis due to Bacterial Infection - Prognosis

Answer 31

Primary morbidity is dysfunction of the joint (should be avoidable if treated promptly. Poor outcome more likely if >60yo, infection of hip or shoulder, underlying RA, positive synovial fluid culture. Mortality rate depends on organism; low with N. gonorrhoeae, up to 50% with S. aureus.

Question 32

Lyme Disease

Answer 32

Most common vector-borne illness in US, spirochete Borrelia burgdorferi. Geographic distribution expanding; currently NE, mid-Atlantic, upper Midwest. On West Coast N. CA & S. OR, w/most infections between May & November.

Question 33

Lyme Disease - Prognosis

Answer 33

Excellent if treated early & appropriately! If treatment is late chronic arthritis, fatigue, and memory/concentration challenges may develop. 10-20% with appropriate tx experience lingering symptoms (chronic lyme or post-treatment lyme). Rarely fatal.

Question 34

Lyme Disease - SSx Stage 1

Answer 34

Stage 1: Localized, 1-30 days from tick bite. Erythema migrans after 1 week enlarging by a few cm/day. Can have multiple lesions from hematogenous spread. 50% get flu-like sx (high fever suggests coinfection). M/b regional LA, conjunctivitis & photophobia.

Question 35

Lyme Disease - SSx Stage 2

Answer 35

Stage 2: Early disseminated, 3-10 wks after infxn, oval erythematous macules on skin, fever, malaise, intermittent migratory polyarticular arthritis (knee, ankle, wrist) w/red, tender swolen joint. (Neurological are important) HA, cranial neuropahies (Bell’s palsy), meningitis, encephalopathy (cofusion, disturbed memory/mood/sleep/concentration/depression/irritability), optic nerve dz (blurred vision). Cardiac arrhythmias, heart block, myopericarditis.

Question 36

Lyme Disease - SSx Stage 3

Answer 36

Stage 3: Late/chronic Lyme, months/years after infxn. Hallmark is lyme arthritis, knee invovled in 90%, erythema, swelling, tenderness, rarely erosion. M/b sx of fibromyalgia. *Neuropathies, encephalopathy, radicular pain, seizures/ataxia/hemiparesis/cognitive impairment, bladder dysfunction, hearing loss. Keratitis, retinal detachment & other eye things.

Question 37

Lyme Disease - Dx

Answer 37

ELISA IgG & IgM is a bad screen! 32% false negative in early dz. If it does show positive, confirm with Western blot.
CBC m/b elevated WBC. Leukopenia/thrombocytopenia suggests co-infection. Liver enzymes are often elevated on CMP. PCR gives direct evidence of Lyme DNA but gives many false negatives. Difficult to culture. CD57 depression has been suggested to confirm or rule-out Lyme. Joint aspiration may show WBC 25,000-125,000. ECG shows fluctuating levels of AV block.

Basically - it’s hard to dx!

Question 38

Viral Arthritis

Answer 38

Usu. self-limiting. Many viruses possible (parvovirus, HBV, HCV, rubella, mumps, HIV). More likely polyarticular than bacterial arthritis, jt pain & swelling less severe.

Question 39

Bursitis definition & causes

Answer 39

Inflammation of bursa.
Acute: pain & bursal effusion.
Chronic: thickened bursal wall with proliferative synovial lining. Bursal adhesions, villus formation, tags, and chalky deposits can develop.
Causes: Injury, chronic overuse, inflammatory arthritis (gout, RA), acute or chronic infection. Most commonly idiopathic or traumatic.

Question 40

Bursitis SSx

Answer 40

Acute: joint pain, esp. during movement, joint swelling. Most commonly olecranon & prepatellar bursae.
Chronic: May recur frequently, bouts last days-weeks. If inflammation persists range of motion may be limited. Common bursae: subacromial (esp w/rotator cuff tendonitis), olecranon, prepatellar, suprapatellar, ischial, treater trochanteric, pes anserine, first metatarsal head bursa (bunion)

Question 41

Bursitis Dx

Answer 41

Clinical. U/S + MRI useful for deep bursae. If swelling is very painful, red, or warm, infection & crystal-induced dz should be excluded by bursal aspiration.

Question 42

Tendonitis & Tenosynovitis definitions + cause

Answer 42

Tendonitis: inflammation of tendon, usu frpm repeated small tears or degenerative changes over years.
Tenosynovitis: tendonitis with inflammation of tendon sheath lining.

Cause: repetitive microtrauma, risk increased with quinolone antibiotics, RA, scleroderma, gout ReA, DM

Question 43

Tendonitis & Tenosynovitis SSx + Dx

Answer 43

SSx: Pain on movement, welling tendon sheath (more with infxn, RA, or gout), TTP along the tendon, m/b friction rub with movement in systemic sclerosis.
Dx: Clinical, MRI + U/S

Question 44

Myalgias

Answer 44

Muscle pain caused by a variety of infections (usu viral), autoimmune conditions, muscle injury/overuse, metabolic disorders, and drugs (statins).

Question 45

Fibromyalgia definiton + etiology

Answer 45

Disorder of unknown cause characterized by MS pain, stiffnes, fatigue, cognitive difficulties, + poor sleep. Often concomitant with IBS, anxiety, or depression. Thought to be a disorder of pain sensitivity. Occurs most in young women 7:1. Sleep disruption may contribute to devleopment, m/b precipitated by systemic infection, stress, or emotional trauma.

Question 46

Fibromyalgia SSx

Answer 46

Gradual onset, achy quality to pain + stiffness, worse with use. Sx widespread, BL, above & below the waist. Many patients feel pain with pressure anywhere, not just “tender-points.” Significant fatigue, poor sleep, HA common, IBS sxs common (abdominal pain, gas, bloating). Sxs can be exacerbated by stress, poor sleep, trauma, and cold or damp.

Question 47

Fibromyalgia Dx

Answer 47

Labs & imaging normal, used to r/o other conditions (CBC, CMP, ESR/CRP, TSH, CK, vit D, Hep panel). Antipolymer antibody assay positive in 50%. Self-report forms can be used to assess sx severity & tx progress (fibromyalgia impact questionaire, PHQ-9, Beck Anxiety, Mood Disorder Questionaire)

Question 48

Polymyalgia Rheumatica

Answer 48

Chronic inflammatory condition characterized by proximal myalgia of hip & shoulder girdles. Inflammation starts w/synovium or bursae, non-erosive synovitis & tendonitis cause sxs. No evidence of dz on m. biopsy & m. strength normal. Possible cell-mediated injury to blood vessels in affected muscle groups. Often associated w/giant cell arteritis.

Question 49

Polymyalgia Rheumatica etiology

Answer 49

Genetic assoc. w/HLA-DR4, risk increases w/age, most around 72 yo. Whites most often, African Americans rarely, 2x as common in females.

Question 50

Polymyalgia Rheumatica SSx

Answer 50

Abrupt onset. Pain/stiffness can start unilaterally but becomes symmetric w/in weeks. Usu starts in shoulder girdle, but can start in hip or neck. General (fever, wt loss, malaise, fatigue) may precede MS sx by 6 mos. MS ssx: severe morning stiffness >1hr, and after rest (difficulty completing ADLs). TTP w/decreased active ROM in proximal hip/shoulder girdle. Synovitis of those jts & periarticular structures, peripheral arthritis in 25%, carpal tunnel in 15%. Muscle weakness is not a feature, BUT atrophy can occur b/c of disuse from pain.

Question 51

Polymyalgia Rheumatica Dx

Answer 51

Labs: elevated ESR (>40-100), normo-normo anemia, platelets elevated, CRP elevated, creatinine kinase normal (distinguishes it from myopathic disorders), IL-6 elevated + mirrors activity of dz.
Imaging: MRI + U/S show bursitis/synovitis.
Temporal artery biopsy if signs of vasculitis develop. Corticosteroids relieve sxs (part of dx).

Diagnostic criteria = more than 4 of:
Morning stiffness >45min (2pts)
Hip pain/limited ROM (1pt)
Absence of RF +/or anti-CCP (2pts)
Absence of peripheral jt pain (1pt)