Transcript Bones, Joints, and Soft

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* Bone modeling, remodeling, and peak bone mass
* Osteoprogenitor cells
* Osteoblasts and lining cells
* Osteocytes - mechanotransduction
* Osteoclasts
* Proteins of bone matrix – Table 26-1
* Lamellar bone gradually replaces woven bone
during growth and is deposited much more slowly
and is stronger than woven bone
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* Bone Growth and Development
* Homeobox genes
* Primary center of ossification
* Secondary center of ossification
* Growth plate (physis)
* Intramembranous formation
* Appositional growth
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* Developmental Abnormalities in Bone Cells, Matrix, and Structure
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Malformations and disease caused by defects in nuclear proteins and
transcription factors
Diseases caused by defects in hormones and signal transduction
mechanisms
Diseases associated with defects in extracellular structural proteins
Diseases associated with defects in folding and degradation of
macromolecules
Diseases associated with defects in metabolic pathways ((enzymes, Ion
channels, and transporters)
Diseases associated with decreased bone mass
Diseases caused by osteoclast dysfunction
Diseases associated with abnormal mineral homeostasis
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* Osteogenesis Imperfecta
* Brittle bone disease
* Deficiency in the synthesis of type 1 collagen
* Childhood fractures, blue sclera, hearing loss,
dental abnormalities
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* Mucopolysaccharidoses
* Abnormalities in hyaline cartilage
* Short stature, chest wall abnormalities,
malformed bones
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* Osteopetrosis
* Marble bone disease ( Albers-Schonberg disease)
* Reduced bone resorption and diffuse symmetric
skeletal sclerosis
* Impaired formation or function of osterclasts
* Fractures, anemia, hydrocephaly
* Cranial nerve defects
* Infections
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* Osteoporosis
* Porous bones and reduced bone mass
* Categories of generalized osteoporosis
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Table 26-4
* Pathophysiology of postmenopausal and senile osteoporosis –
Figure 26-9
* Pathogenesis
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Age-related changes
Reduced physical activity
Genetic factors
Calcium nutritional status
Hormonal influences
Clinical – vertebral fractures, bone density tests
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* Paget disease (osteitis deformans)
* Three phases
* Initial osteolytic stage
* Mixed osteoclastic-osteoblastic stage
* Burnt-out quiescent osteosclerotic stage
* Pathogenesis
* Mosaic pattern of lamellar bone
* Uncertain cause
* Clinical
* Elderly, often incidental finding, axial or proximal femur –
80%, pain heavy cranium, severe secondary osteoarthritis.
tumors, fractures
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* Rickets in children = osteomalacia in adults
* Hyperparathyroidism
* Osteitis fibrosa cystica = severe
* Increased bone cell activity, peritrabecular
fibrosis, cystic brown tumors
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* Renal Osteodystrophy
* Increased osteoclastic bone resorption
* Delayed matrix mineralization
* Osteosclerosis
* Growth retardation
* Osteoporosis
* Pathogenesis
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CRF -> phosphate retention -> secondary hyperparathyroidism
Hypocalcemia develops because of decreased levels of 1,25
dihydroxy D3
Increased osteoclast activity
Metabolic acidosis
Amyloid in bone from dialysis
* Fractures
* Complete or incomplete
* Closed (simple)
* Compound
* Comminuted
* Displaced
* Pathologic
* Stress
* Repair
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Hematoma surrounds fracture-> creates framework-> soft-tissue
callus -> bony callus -> reduced in size and shape until original
outline is reestablished and medullary cavity is restored
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* Osteonecrosis ( Avascular necrosis)
* Conditions associated with osteonecrosis
* Table 26-5
* Trauma and corticosteroid use most common
* Creeping substitution
* Chronic pain, secondary arthritis
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* Infections – osteomyelitis
* Pyogenic
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Hematogeneous spread
Extension from a contiguous site
Direct implantaiton
Organisms
* S.aureus 80-90%
* Gram negatives
* H.flu and GroupB strep in neonates
* Salmonella in sickle cell anemia
* TB – Pott disease – TB of the spine
* Skeletal syphilis – nose, palate, skull, and extremities, “saber
skin”
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* Bone tumor and tumor-like Lesions
* Bone-forming tumors
* Cartilage-forming tumors
* Fibrous and fibro-osseous tumors
* http://www.pediatricsconsultant360.com/BoneTumors-Childhood
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* Classification of Major Primary Tumors involving
bones – Table 26-6
* Bone forming
* Osteoma - sessile tumors, Gardner syndrome
* Osteoid osteoma - < 2cm, nocturnal pain relieved
by aspirin, teens and 20’s
* Osteoblastoma - > 2 cm, pain not responsive to
aspirin
* Osteosarcoma – Malignant mesenchymal tumor,
cancerous cells produce bone matrix, RB and p53,
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* Osteosarcoma
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Most common primary malignant tumor of bone, exclusive of myeloma
and lymphoma
Bimodal age distribution – 75% < 20 years of age, rest elderly with
Paget, bone infarcts, proior irradiation
Figure 26-21 Major sites of origin
Subtypes
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Site of origin
Degree of differentiation
Multicentricity
Primary or secondary
Histologic features
Clinical – Codman triangle, Painful, enlarging mass or pathologic
fracture
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* Cartilage-forming tumors
* Osteochondroma – exostosis, most common benign bone
tumor, multiple hereditary exostosis syndrome, bones of
endochondral origin, metaphysis near growth plate
* Chondromas – endrochondromas, subperiosteal or
juxtacortical, Ollier disease, Maffuci syndrome, most are
incidental findings
* Chondroblastoma – epiphysis or apophyses, painful, joint
findings
* Chondromyoxoid fibroma
* Chondrosarcoma – intramedullary or juxtacortical
(surface), conventional,clear cell, dedifferentiated,
mesenchymal, central portion of the skeleton
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* Fibrous and fibro-osseous tumors
* Fibrous cortical defect and non-ossifying fibroma
* Fibrous dysplasia – monostotic or polyostotic
without endocrine dysfuntion, poyostotic with
café-au-lait spots and endocrinopathies (
McCune-Albright syndrome)
* Fibrosarcoma variants
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* Miscellaneous Tumors
* Ewing sarcoma/primitive neuroectodermal tumor
– (11;22) (q24;q12) translocation, Homer-Wright
rosettes
* Giant-cell tumor – osteoclastoma
* Aneurysmal bone cyst – multiloculated bloodfilled cystic spaces
* Metastatic disease – most common form of
skeletal malignancy
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* Arthritis
* Osteoarthritis
* Rheumatoid arthritis
* Juvenile idiopathic arthritis
* Seronegative spondyloarthropathies
* Infectious arthritis
* Crystal-induced arthritis
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* Osteoarthritis
* Degenerative joint disease
* Progressive erosion of articular cartilage
* Primary or secondary
* Chondroytes, joint mice, bone eburnation
* Deep,achy pain that worsens with use, morning
stiffness, crepitus, limitation of ROM, hips,
knees, lowerlumbar, cervical vertebrae, PIP And
DIPs first carbometacarpal and first
tarsometatarsal, Heberden nodes at DIP
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* Rheumatoid Arthritis
* Chronic systemic inflammatory disorder that may affect
many tissues and organs, - skin, blood vessels, heart,
lungs, and muscle – but principally the joints, producing a
nonsuppurative proliferative and inflammatory synovitis
that often progresses to destruction of the articular
cartilage and ankylosis of the joints
* Pannus, fibrous ankylosis, rheumatoid nodules
* HLA-DRB1
* Immunopathogenesis – Figure 26-44
* Symmetrical , small joints before large, warm,painful,
stiff, joint effusions, juxtaarticular osteopenia, erosions
and narrowing of joint space on x-ray, RF
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Juvenile idiopathic arthritis
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Classification
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Systemic arthritis – fevers, fleeting ras, hepatosplenomegaly, serositis
Oligoarthritis – ANA+, iridoylitis
RF-positive polyarthritis
RF-negative polyarthritis
Enthesitis-assocaited arthritis – HLA-B27
Psoriatic arthritis
Undifferentiated arthritis
Differs from adult RA
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Oligoarthritis is more common
Systemic is more frequent
Large joints> small joints
RF and nodules absent
ANA+
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* Seronegative spondyloarthropathies
* Ankylosing spondyloarthritis – HLA-B27
* Reiter syndrome – with nongonococcal urethritis
or cervitis and conjunctivits, HLA-B27, HIV
* Enteritis-associated arthritis – GI infections
* Psoriatic arthritis – HLA-B27 and HLA-Cw6
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* Infectious Arthritis
* Bacterial
* TB
* Lyme
* Viral
* Crystal-Induced Arthritis
* Gout and Gouty arthritis
* Classification – Table 26-7
* Precipitation of monosodium urate crystals in the
joints
* Acute arthritis, chronic tophaceous arthritis, gouty
nephropathy
* Calcium pyrophosphate crystal deposition disease
(pseudo-gout)
* Tumors and Tumor-like lesions
* Ganglion and synovial cyst
* Tenosynovial Giant-cell tumor (localized and
diffuse)
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* Pathogenesis and general features – Table 26-8
* Fatty tumors
* Fibrous tumors and tumor0like lesions
* Fibrohistiocytic tumors
* Tumors of skeletal muscle
* Tumors of smooth muscle
* Synovial sarcoma
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