Musculoskeletal Flashcards
Mixed connective tissue disease
Overlapping features of SLE, polymyositis, and systemic sclerosis
Presentation: Raynaud phenomenon Swollen fingers Arthritis Inflammatory myopathy Pleuritis Pulmonary fibrosis
Dx: Anti-U1-RNP Ab
Gout
Deposition of monosodium urate crystals
Risk:
Hyperuricemia
Underexcretion of uric acid - loop diuretics, thiazides
Overproduction of uric acid
Consumption of purine-rich foods (meat, seafood, alcohol)
Obesity
Male sex
Features: Acute attack of severe monoarticular arthritis -podagra -kne, ankle, hip, or wrist -Red, warm, swollen, exquisitely painful
Chronic tophaceous gout - subcutaneous urate deposits on joints, tendons, bursar, ears - non painful
Dx: serum uric acid level - normal or increased
Aspiration: needle shaped, negatively birefringent crystals (yellow when parallel) and WBCs
Tx: Acute: NSAIDs - naproxen, indomethacin, celecoxib Glucocorticoids Colchicine
Longterm:
Lifestyle modification
Probenecid - inhibits uric acid resorption
Allopurinol or febuxostat - inhibits uric acid production - inhibits xanthine oxidase
Colchicine
Pseudogout
Calcium pyrophosphate dihydrate crystals
Features:
Acute attacks- knee
Wrist, elbow, shoulder, ankles, feet
Dx:
Aspiration: rhomboid-shaped, positively birefringent crystals (blue)
XR: chonedrocalcinosis (calcification of articular cartilage)
Tx:
Intra-articular steroid injection for mono- or oligoarthritis
NSAIDs or colchicine for polyarthritis
Septic arthritis
Usually hematogenously spread
MC: S. aureus
Strep spp.
N. gonorrhoeae - asymmetric polyarthritis - knees, wrists, ankles; pustules/papules on hands and feet
Risk: Prosthetic joints Skin infection IV drug use Alcoholism Preexisting inflammatory arthritis - RA DM Recent joint surgery
Features:
Monoarticular arthritis -> pain/tenderness, redness, warmth, restricted ROM
Usually knee, may affect wrist, hips, ankles
Dx: Elevated ESR and CRP Leukocytosis 50% positive blood cx Aspiration >50,000 WBC, neutrophil predominance
Tx: Drainage and irrigation of joint Empiric IV abx guided by gram stain -Gram positive - Vancomycin -Gram negatives - 3rd gen cephalosporin (Ceftriaxone) -Negative gram stain - Vancomycin
Cause of lyme disease
Borrelia burgdorferi
Vector - Ixodes scapularis tic
Lyme disease
Early localized: 7-14 days after tick bite
-erythema chronicum migrant - target rash with central clearing that expands over days to weeks
-fatigue, HA, myalgia, arthralgia
Tx: Doxycycline 100 mg BID x 14 d (avoid in pregnancy)
-Amoxicillin or cefuroxime x 3 weeks
Early disseminated: weeks to months after bite
-Lymphocytic meningitis
-U/l or B/L CN palsies - esp bilateral bells palsy
-Peripheral neuropathy
-Radiculopathy
-Carditis (Av block, myopericarditis)
-Ocular - conjunctivitis, keratitis, uveitis
Dx: positive IgM and IgG; ELISA and Western Blot
Tx: Isolated bell’s palsy - PO doxycycline, amoxicillin, or cefuroxime
-Meningitis or other manifestations - IV ceftriaxone, cefotaxime, or pcn G x 28 days
Late: months to years Arthritis - esp knee Mild encephalopathy - mild cognitive disturbance Dx: No IgM, positive IgG Tx: Doxycycline or amoxicillin x 1 mo
Osteoporosis
Reduced osteoblast activity -> decreased bone mass
Risk: Decreased estrogen Decreased testosterone Asian and Caucasian race Sedentary lifestyle Low body wt Smoking etOH use Inadequate calcium intake Hyperparathyroidism Hyperthyroidism Glucocorticoid use
Presentation: asx or fractures - wrist, femoral neck, vertebrae
Dx: Labs normal XR: decreased bony opacity - osteopenia DEXA - T score -Normal: -1 or greater -Osteopenia: -1 to -2.5 -Osteoporosis: greater than -2.5
Tx:
Lifestyle changes: smoking cessation, reduce etOH, wt bearing exercise, Ca-VitD supplements
Bisphosphonates - alendronate, risedronate, ibandronate
-inhibit osteoclasts
Raloxifene - selective estrogen receptor modulator - increased risk of VTE and PE
Teriparatide - PTH analogue stimulates osteoblasts - daily SC injection
Denosumab - RANK-L inhibitor - inhibits osteoclasts
Osteopetrosis
Genetic impairment of osteoclast activity -> abnormally dense bone
Presentation:
Increased risk of fractures
Hearing loss - narrowing auditory foramen, acoustic n. compression
Vision loss - compression of optic n.
Pancytopenia - obliteration of marrow space -> infection
Thickening of bones in skull -> increased skull circumference - hats don’t fit
Dx:
labs normal
Pancytopenia possible
XR long bones: flared ends - erlenmeyer flask
Tx: bone marrow transplant - healthy monocytes become healthy osteoclasts
Osteomyelitis
Contiguous spread, direct inoculation, hematogenous spread
Often polymicrobial:
- S. aureus
- Coagulase-negative Staph spp (S. epidermidis)
- Gram negative - bacilli (E. coli, Klebsiella, Salmonella)
- Sickle cell - consider salmonella
- IV drug user - consider pseudomonas
- DM foot ulcer - consider pseudomonas
Presentation:
Dull bone pain - gradual over several days
fever and inflammation of overlying skin
Dx:
Leukocytosis, elevated ESR and CRP, +/- positive blood cultures
XR: erosion of bone cortex and periosteal reaction
MRI more sensitive
Nuclear medicine helpful
Surgical bone bx and culture
Tx: Surgical debridement IV abx x 6 weeks - vancomycin + cefepime Infected hardware removed may require amputation if significant destruction of bone
Primary cancers that frequently metastasize to bone
“permanently relocated tumors like bones”
Prostate - blastic Renal cell Testes and Thyroid Lung - lytic Breast - lytic or blastic
Presentation:
Bone pain
Pathologic fx
Hypercalcemia with lytic bone lesions
Osteosarcoma
MC malignant bone tumor
Teen boys or adults over 65 (arise from Paget dz of bone)
Rb gene mutation
Prior chemo/radiation
Distal femur/proximal tibia
XR: Codman’s triangle, sunburst pattern
Tx: surgery and chemo
Ewing sarcoma
Boys under 15
t(11;22)
Grows on surfaces of long bones and pelvis
XR: Onion skin appearance
Tx: chemo and surgery
Giant cell tumor
Multinucleate giant cells - osteoclastoma
Young adults 20s-30s
Distal femur/proximal tibia
benign but locally invasive
XR: soap bubble appearance
Tx: surgery or radiation
Osteochondroma
MC benign bone tumor
Males less than 25
Painless bone mass, often palpable
XR: Large “chunk” of bone with a cartilage cap
Tx: surgical excision only for soft tissue irritation or bone deformity
Carpal tunnel syndrome
Median N compression at wrist
Risk: obesity, female, pregnancy, DM, RA, hypothyroidism, connective tissue dz, overuse
Presentation:
numbness of thumb, index finger, middle finger, radial half of 3rd finger
Tinel test
Phalen test
Nerve conduction study
EMG
Tx: wrist splints, activity modification
NSAIDs
glucocorticoid inj
surgical release of transverse carpal ligament
Ulnar claw
ulnar n. innervates 3rd and 4th lumbricals, interosseous, adductor pollicis
Injury causes:
hyperextension at MCP of 4th and 5th digits
Flexed at IP joints of 4th and 5th digits
Apparent when asked to extend fingers
