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41 Cards in this Set

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Describe a Fracture after 2 days
1. Blood Clot is formed
- good b/c blood has lots of Growth Factors to enhance repair & healing

2. At periphery & Endosteum, there is marked proliferation of Osteoblasts

3. There is no overt Callus formation (Callus = new bone)
Describe a Fracture after 1 week
1. Primary Callus forms at broken ends of bone

2. Outside is Cartilage & is a sign that repair is due to Endochondral formation = indirect bone formation from a "cartilage model"
3. Endosteum is usually linked by Callus, bone
Describe Fractures month-years post fracture
1. Osteoclasts dissolve the temporary bone & Osteoblasts lay new bone

2. The action of Osteoblasts maximally resist fracture at the same location; if you bend the bone it will rarely fracture in the same place
Autosomal Dominant mutation in Fibroblast Growth Factor Receptor 3 (FGFR3) that causes impaired proliferation of Cartilage at the Growth Plate
Achondroplasia
Achondroplasia = bone is short but broad at the Epiphysis
-narrow Epiphyseal Plates & Bony sealing off of the area between the Epiphyseal Plate & Metaphysis
What is this picture showing?
Achondroplasia
-Growth Plate is disordered, cells are not in a regular array
-Activation of FGF#3 inhibits Cartilage synthesis at the Epiphyseal Growth Plate, resulting in decreased Endochondral Bone formation & premature ossification of Growth Plates
What is seen here?
Achondroplasia = mutation in FGFR3
-short & thick Long bones
-Cranial & vertebral bones are spared = relatively large head & trunk
What is the cause?
Autosomal dominant disease resulting in defective synthesis of Collagen type I & insufficient Bone Matrix synthesis
Osteogenesis Imperfecta
Pathogenesis: A reduction in Bone Matrix, which alouth fully calcified, results in fragile bones that are more prone to fracture
Osteogenesis Imperfecta
Osteogenesis Imperfecta = abnormal synthesis of Collagen I
What is the cause of this?
What are the clinical features of Osteogenesis Imperfecta?
1. Generalized Osteopenia (brittle bones) = recurrent fractures & skeletal deformity
2. Blue Sclera
3. Early tooth loss
4. Joint Hypermobility
5. Deafness = due to involvement of teh bones of Inner & Middle ear
Osteogenesis Imperfecta
-bones are calcified but hypodense b/c they are thin
-bent tibia shows fracture
What is the cause of this?
Osteogenesis Imperfecta
-Cortex is very thin
-Bone Trabeculae are thin, widely spaced, & fragile looking
What is seen here?
Osteogenesis Imperfecta
-Osteocytes are very close together = indicates insufficient Matrix synthesis
-Osteoblasts can't secrete enough Collagen I
-Blue staining shows that it is fully Calcified = not due to improper calcification
What is seen here?
Osteogenesis Imperfecta
-there is no impairment of Endochondral bone formation
-if you see a fracture site, you see excessive Cartilage formation since Collagen II is not impaired
What is seen here?
Osteogenesis Imperfecta post-fracture
-Cortex is thin
-can be mistaken for Osteosarcoma
What is seen here?
Hereditary disease with decreased Osteoclast function leading to decreased resorption & thick sclerotic bones
Osteopetrosis
What is the pathogenesis of Osteopetrosis?
Impaired Osteoclastic resorption of bone leads to excessive bone formation
Osteopetrosis
-Anemia, Thrombocytopenia = due to Trabeculae crowding out Bone Marrow
Diagnosis?
Osteopetrosis = dysfuction of Osteoclast activity
-"Erlenmyer Flask"-shaped deformity
What is the cause of this?
Osteopetrosis
-projections of dense bone down into the Metaphysis
What is the cause of this pathology?
Osteopetrosis
-persistence of lots of Cartilage in the matrix of Medullary Bone
-lack of Trabeculae or Hematopoietic marrow
What is seen here?
Osteopetrosis
-marked thickening of Trabeculae -> crowds out Bone Marrow
-Manifested by Anemia, Thrombocytopenia
What is this?
What is the Etiology of Fibrodysplasia Ossificans Progressiva (FOP)? Pathogenesis?
Etiology: mutated genes for Bone Morphogenetic Proteins (BMP's)

Pathogenesis: in childhood, Osteoprogenitor cells of muscle begin progressive Endochondral Bone formation, in one muscle group after another
Fibrodysplasia Ossificans Progressiva (FOP)

Overexpression of Bone Morphogenetic Proteins in muscle
-Osteoprogenitor cells of muscle, which normally wait for a fracture to occur so they can make a callus, go haywire & make bone in muscles
This girl has a piece of bone in her Sternocleidomastoid muscle...what is the name of the disease? What is the cause?
Fibrodysplasia Ossificans Progressiva
What disease is this?
Fibrodysplasia Ossificans Progressiva
-cannot surgically resect b/c it would cause more reactive bone formation
This is seen in muscle. What disease?
Fibrodysplasia Ossificans Progressiva
What end-stage disease is this?
What are the most common causes of Hypertrophic Osteoarthropathy?
1. Bronchogenic Carcinoma = paraneoplastic syndrome
2. Chronic lung diseases
3. Cyanotic congenital heart disease
4. Inflammatory Bowel Disease
Avascular Necrosis = ischemic necrosis of bone & bone marrow
What pathology is seen here?
What are the most common causes of Avascular Necrosis?
1. Steroid use
2. Sickle Cell anemia
3. Caisson disease = decompression syndrome
Advanced Avascular Necrosis
-pitted surface & cartilage disappears in places
-painful lesion
What is seen here?
Joint Mouse in Avascular Necrosis
-cartilage that was covering it regenerates & grows all around the outside -> causes difficulty in Articulation -> joints make a squeaky sound when bended
What is seen here?
Osteomyelitis
-Staphylococcus Aureus = MCC
-E. coli, Klebsiella, Salmonella
What is seen here? What are the most common causes?
Osteomyelitis
-Marrow space fills up with PMN's
-PMN's enzymatically destroy the bone
What is seen here?
Sequestrum in Osteomyelitis = necrotic bone due to compression of vasculature by Pyogenic Exudate
What is seen here?
Involucrum surrounding the Sequestrum
-Involucrum = Reactive Bone Formation in the periosteum = has Lamellar appearance
What is seen here?
Osteomyelitis
-Gelatinous inflammatory infiltrate in the medullary space = Sequestrum
-along the outside is new bone formation = Involucrum
What is seen here?
Osteomyelitis of the Phalanx
-infection has broken thru the bone, into the joint & has moved onto the next joint
-if infection hits the Growth Plate, it'll stop the growth of long bones = important in children
What is happening here?
Osteomyelitis that has drained to the outside
-predisposes to Squamous Cell CA of the skin
What is this picture showing?
Brodie's Abscess = surrounding wall of granulation tissue of inactive inflammation
-post-osteomyelitis
What is seen here?