Osteogenesis Imperfecta: Auto dom, defect in synthesis type I collagen Blue Sclera: reflection of underlying choroidal veins—ie in osteogenesis
imperfect
Achondroplasia
o Auto dom, mutation in fibroblast growth factor receptor gene o Normal head/axial skeleton, short arms/legs
Osteopetrosis
o Deficiency of osteoCLASTS—too much bone o Pathologic frx, visual/hearing loss
Osteomyelitis
o usually hematogenous spread to bone, metaphysis—most common site
o S. aureus—most common pathogen o Salmonella—sickle cell pts
o TB—Pott’s dz = vertebral column involvement o Pseudomonas—puncture through rubber soled shoe
Sequestra: devitalized bone
Involucrum: reactive bone formation in periosteum Draining Sinuses: danger of squamous cancer Osteoporosis
o Most common metabolic abnormality of bone
o Loss of mineralized bone + organic bone matrix (osteoid) o Women > men
o 2° Causes: ↑cortisol, heparin, hypogonadism, malnutrition, space travel
o Dx: dual photon absorptiometry
o Prevention: weight-bearing exercises, Ca, Vit D, stop smoking o Rx: bisphosphonates 1st
line drug
Estrogen: inhibits production of osteoclasts, enhance osteoblast ↓Estrogen: ↑ osteoclastic activity, ↓osteoblastic activity Postmenopausal Osteoporosis: compression vertebral frx—most
common
Aseptic Necrosis
o disruption of microcirculation causes bone infarctions o femoral head most common site
o subcapsular frx disrupts blood supply
o Scaphoid Bone: most common wrist bone frx, susceptible to aseptic necrosis
o Localized pain
o MRI most sensitive early tests
Osteochondrosis: aseptic necrosis of ossification centers
Legg-Calve-Perthes Dz: aseptic necrosis of femoral head ossification
47 Osteochondritis Dissecans
o variant of osteochondrosis limited to articular epiphysis o trauma 1° insult, ischemia 2° injury
o distal femur—most common site o osteoarthritis late complication
Osgood-Schlatter Dz
o Painful swelling tibial tuberosity in boys o Permanent knobby-appearing knees
Paget’s Dz
o Primarily in men >50yo, ? viral etiology
o Osteoclastic phase followed by an osteoblastic phase o ↑alkaline phosphatase in osteoblastic phase
o Weak, thick, vascular bone
o Complications: frx, osteogenic sarcoma, high-output heart failure
Fibrous Dysplasia
o Defect in osteoblastic differentiation & maturation
o Medullary bone replaced by fibrous tissue w/ cyst formation o Ribs—most common site
o Complications: pathologic frx, osteogenic sarcoma, fibrosarcoma
Albrights Syndrome: polyostotic bone involvement, café au lait spots,
precocious puberty
Metastasis: most common bone malignancy Osteochondroma: most common benign tumor Giant Cell Tumor: epiphysis distal femur, proximal tibia Joint Disorders
Monosodium Urate Crystals (MSU): negative birefringence—yellow
when parallel to slow ray
Calcium Pyrophosphate: positive birefringence—blue when parallel to
slow ray
Group 1: noninflammatory osteoarthritis, neuropathic joint Group II: inflammatory, RA, gout
Group III: septic, Lyme Dz, Disseminated gonococcemi Group IV: hemorrhage, trauma, hemophilia
Morning Stiffness: RA, SLE, polymyalgia rheumatic Joint Effusion: blood, exudate
Hot Joint: acute inflammation, septic arthritis Joint Crepitus: crackling feeling, osteoarthritis
Osteoarthritis: most common disabling joint dz
Alkaptonuria: homogentisic acid deposits in intervertebral disks, black
color
Osteoarthritis
o femoral head, knee, cervical/lumbar vertebrae, hands o wearing down of articular cartilage, bone rubs on bone o osteophytes at joint margins
o clefts, subchondral cysts o no fusion of joint
o pain—most common complaint o joint stiffens after inactivity
Ochronosis: auto rec, deficiency homogentisic acid, osteoarthritis Articular Cartilage: proteoglycans, type II collagen
OA Fingers
o Heberdens’ Nodes—DIP joint enlargement/pain o Bouchard’s Nodes—PIP joint enlargement/pain
OA Vertebral Column: cervical/lumbar, degen disk dz, compression
neuropathies
Neuropathic Joint
o loss of proprioception, deep sensation leading ot recurrent trauma
o Causes: diabetes, syringomyelia, tabes dorsalis
RA
o B cells produce rheumatoid factor (RF), an IgM antibody w/ specificity against Fc portion of IgG
o FR combines w/ IgG to produce immunocomplexes that activate complement
o Hand: involves MCP & PIP joints, bilateral ulnar deviation o Lung: interstitial fibrosis, effusions
o Blood: ACD, AIHA, Felty’s Syndrome—autoimmune neutropenia, splenomegaly
o Cervical Spine: subluxation atlantoaxial joint, cord/vertebral artery compression
o Caplan Syndrome: rheumatoid nodules in lung + pneumoconiosis
o Cardiovascular: pericarditis, aortitis, vasculitis o Labs: +serum RF, ANA
Pannus: granulation tissue, releases cytokines that destroy articular
48 Repair by fibrosis causes fusion of joint—ankylosis
Baker’s Cyst: outpouching of posterior joint space in knee Sjorgren’s Syndrome
o destruction minor salivary glands & lacrimal glands o dry eyes, dry mouth
o Lab: + serum ANA, RF, anti-SS-A/anti-SS-B, lip biopsy confirms
Juvenile Rheumatoid Arthritis
o RF is usually negative
o Still’s Dz: fever, rash, polyarthritis
o Polyarticular: limited arthritis, uveitis & potential for blindness o Pauciarticular: limited arthritis, uveitis, & potential for blindness
Gout
o Male dominant dz
o Most cases dt underexcretion of uric acid
o Associations: urate nephropathy, renal stones, HTN, artery dz, Pb poisoning
Acute Gout
o 1st metatarsophalangeal joint—most often involved o Free uric acid crystals responsible for initiating the attack o Must confirm w/ joint aspiration
o Non-Pharm Rx: eliminate high purine diet, moderation in alcohol intake
o Pharm Rx: NSAIDs or colchicine
o Pharm Prevention: uricosuric agents for underexcretros, allopurinol for overproducers
Tophus: MSU deposits in soft tissue around the joint Calcium Pyrophostate Dihydrate Depositition (CPPD)
o deposition of Ca pyrophosphate in tissues o ↑w/ hemochromatosis, hemosiderosis, 1° HPTH
o OA Variant: knee—most common joint, chondrocalcinosis present
Chondrocalcinosis: linear deposits of Ca pyrophosphate in articular
cartilage
Seronegative Spondyloarthropathies
o RF negative arthritis
o Key Points: - RF, +HLA-B27, male, sacroiliitis, spondylitis
Ankylosing Spondylitis
o Over time develop fusion of vertebrae—bamboo spine o Aortitis, uveitis w/ potential for blindness
Reiter’s Syndrome
o C. trachomatis urethritis, arthritis, conjunctivitis o Achilles tendon periostitis is diagnostic sign
Psoriatic Arthritis: sausage-shaped DIP joints, “pencil-in-cup” deformity N. gonorrhoeae: most common cause of septic arthritis in urban
populations
Disseminated Gonococcemia: septic arthritis, tenosynovitis, dermatitis B. burgdorferi: gram – spirochete, cause of Lyme Dz
Lyme Dz
o vector Ixodes tick, reservoir white-tailed deer
o Erythema Chronicum Migrans: pathognomonic of Lyme Dz o Disabling arthritis, Bell’s Palsy, Myocarditis
Babesiosis: tick-transmitted hemolytic anemia
Pasteurella multocida: septic arthritis/tendinitis dt cat/dog bite Muscle Disorders
Type I: slow-twitch (red), rich in mitochondria, oxidative enzymes, poor
in ATPase enzymes
Type II: fast-twitch (white), poor in mitochondria, oxidative enzymes, rich
in ATPas enzymes
Muscle Weakness: motor neuron, neuromuscular synapse, muscle
dysfxn
Neurogenic Atrophy: motor neuron of axon degenerates Trichinosis
o Trichnella spiralis (nematode), from eating encysted larvae in pig muscle
o Calcified larvae visible on Xray
o Muscle pain, periorbital edema, splinter hemorrhages o Pronounced eosinophilia
Invasive Group A Strep
o Necrotizing fasciitis, myositis, Strep Toxic Shock Syndrome o Exotoxin A (superantigen), exotoxin B (protease)
Duchenne’s Muscular Dystrophy (DMD)
o X-linked rec, absence of dystrophin o Pseudohypertrophy of calf muscles
o Waddling gait dt weakness of pelvic muscles o ↑ serum CK at birth, ↓as muscles degenerate
Myotonic Dystrophy
49
o CTG trinucleotide repeat
o Sagging face, frontal balding, cataracts, testicular atrophy, cardiac involvement
o Autoantibodies against Ach receptors, synthesized in thymus o Ptosis, diplopia common finding
o Oropharyngeal dysphagia for solids/liquids
Myotonia: inability to relax muscles Tensilon: inhibits AChase
Soft Tissue Disorders
Dupuytren’s Contracture: fibromatosis palmar fascia Liposarcoma: most common adult sarcoma
Unhappy Triad: damage to medial meniscus, MCL & ACL Soft Tissue Tumors
o Lipoma: trunk, neck, prox extremities, most common BENIGN soft tissue tumor, from subQ tissue
o Liposarcoma: thigh, retroperitoneum, most common adult sarcoma, lipoblasts IDed w/ fat stains
o Fibrosarcoma: thigh, upper limb, after irradiation
o Dermotafibroma: LE, benign, spindle cells prolif in dermins, umbilicated red nodule
o Malignant Fibrous Histiocytoma: retroperitoneal, thigh, radiation therapy & scarring
o Rhabdomyoma: heart, tongue, vagina, benign, associated w/ tuberous sclerosis
o Embryonal Rhabdomyosarcoma: penis & vagina, most common sarcoma in kids, grape-like necrotic mass
o Leiomyoma: uterus—most often, stomach o Leiomyosarcoma: GI tract & uterus
o Neurofibrosarcoma: major nerve trunks, associated w/ neurofibromatosis
o Synovial Sarcoma: around joints, does NOT arise from synovial cells—mesenchymal cells, biphasic patterns—epithelial cells forming glands + intervening spindle cells
Orthopedic Disorders
Colle’s Fx: FOOSH, distal radius fx w/ or w/out ulnar styloid fx Rotator Cuff Tear: supraspinatus, infraspinatous, teres minor,
subscapularis, pain/weakness w/ ABduction
Tennis Elbow: extensor tendon pain, lateral epicondyle Golfers Elbow: flexor tendon pain, medial epicondyle
DeQuervain’s Tenosynovitis: chronic stenosing tenosynovitis of 1st dorsal wrist compartment—ABductor pollicis longus & extensor pollicis brevis, excessive friction thickens tendon sheath, Finkelstein’s Test—ulnar deviat.
Ganglion (Synovial) Cyst: bulge on wrist dorsum when flexed, F>M Compartment Syndrome: ↑pressure in fascial compart., ischemia, 5Ps—
pain, paresthesias, pallor, paralysis, pulselessness, Volkmann’s Ischemic
Contracture—displaced supracondylar fx of distal humerous causing
compression of brachial artery & median nerve
Carpal Tunnel Syndrome: median nerve entrapment, causes—RA,
pregnancy, obesity, excessive use, acromegaly, ape hand, Dx—Phalens & Tinels
Intervertebral Disk Dz: degen of fibrocartilage/nucleus pulposus,
ruptured disk may herniated posteriorly & compress nerve root/cord o Radicular Pain: leg pain aggravated by straight leg raising o L3-L4 Hern: loss of knee jerk—femoral n. L2-L4
o L4-L5 Hern: NO loss of reflexes
o L5-S1 Hern: loss of ankle reflex—tibial n. L4-S3
Knee Joint Injuries
o Valgus: away from midline via lateral force o Varus: toward midline via medial force o McMurray Test: meniscus injuries
o Anterior/Posterior Drawer Tests: ACL & PCL injuries o Unhappy Triad: medial meniscus, ACL, MCL
Scoliosis: idiopathic—teen girls , usually right thoracic curve