Periosteum consists of dense irregular connective tissue. Periosteum is divided into an outer "fibrouslayer" and inner "cambium layer" (or "osteogeniclayer"). The fibrous layer contains________, while the cambium layer contains progenitor cells that develop into osteoblasts.
(A progenitor cell is a biological cell that, like a stem cell, has a tendency to differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its "target"cell.)
Periosteal response with a smooth, even shape and well-defined margin. New bone production appears multilaryered and suggestive of ____ growing disease.
Irregular-shaped periosteal response with well-defined margins, no cortical destruction, and abssence of soft tissue swelling is indicative of?
Incactive, nonaggressive disease process.
Irregular-shaped periosteal response with ill-defined margins, cortical destruction, and soft tissue swelling indicates?
active and aggressive disease process.
What do you call a well-defined wedge-shaped area of new bone at the perihery of an active, aggressive lesion. Underlying cortex is lytic but visible.
What is the definition of Osteopetrosis?
Congenital metabolic bone dz in which endochondral ossification continues, but bone absorption is decreased due to abnormal osteoclastic activity.
What is the difference b/t Osteopetrosis vs. Osteoporosis?
Osteopetrosis is a rare congenital and familial developmental abnormality of skeletal growth of man and animals. The formation and production of the growth plate cartilage cells and matrix and the primary trabeculae are normal. Bone length and shape are relatively normal. There is, however, marked retardation of the remainder of the enchondral ossification cycle which includes bone maturation, resorption of immature bone, bone remodeling and cortex formation beyond the primary trabecular stage. The accumulation and persistence of cores of calcified cartilage, osteoid and primitive bone in the medullary cavities results in abnormally dense bone and has led to the radiographic diagnosis of this disease by such synonyms as osteosclerosis fragilis, marble bones and chalk bones
Osteoporosis is a nonspecific term referring to a condition that is characterized by quantitative loss of bone, that is, atrophy of bone. The bone that is present is entirely normal, since the organic and inorganic phases diminish in equal proportion. The reduced amount of bone is manifested by thinning of the cortex or reduced number and caliber of cancerous trabeculae, or more commonly both. Thus, affected bones are thin, porous, and brittle. The volume of bone remains constant, however.
What is OSTEOSCLEROSIS?
What is the difference b/t osteoSCLEROSIS vs. osteoPETROSIS?
Abnormal hardening or increased density of bone (eburnation)
scleosis=mostly locaised bone deposition, may be generalised too=pathological
petrosis=stony hard bone still easily fragile=generalised bone overdeposition =hereditary/genetic condition
What are the 3 patterns of osteolysis?
What is Osteomyelitis and how does ot occur?
Osteomyelitis is an infection in a bone. Infections can reach a bone by traveling through the bloodstream or spreading from nearby tissue. Infections can also begin in the bone itself if an injury exposes the bone to germs. Infections mainly affects, marrow, Haverisian canals and periosteal spaces.
What is osteomylitis?
or OM) is infection and inflammation of the bone and bone marrow. It can be usefully subclassified on the basis of the causative organism (pyogenic bacteria or mycobacteria) and the route, duration and anatomic location of the infection. Osteomyelitis usually begins as an acute infection, but it may evolve into a chronic condition
With chronic otits, external auditory canal may be narrowed or obscured due to presence of what?
fluid, exudate, debris in lumen or thickening of ear canal lining
Enchondroma is a benign cartilaginous tumor that develops from displaced growth ______? It is a wxpansile, well-defined area of decreased opacity in the medullary cavity of a long bone.
Abnormal differentiation of physeal cartilage leads to development of a bony mass near the physis (mass can develop away from physis if fragment of physeal cartilage breaks off and remains in place as bone grows and physis moves is called?
A nodular proliferation of synovial membrane- ossible from fragments of articular cartilage. Proliferating synovium can extend into surrounding soft tissue. More common in cats than dogs. What is it?
What does a premature closing of the distal unlar physis look like?
What do you call a joint space between the humerous and ulna which is widened and wedged shape?
What do you call a sclerotic fragment of bone sequestrum which is surrounded by a less opaque zone (invulcrum) within a bone?
What can cause a shortened radius and a humeroulnar joint subluxation?
Premature closure of the distal radial physis?
Primary bone tumors (osteosarcomas) are COMMON in dogs and cats. About ____%.
What is the "Zone of Transition"
The appearance of the zone of transition between a lesion and the host bone is probably the single best indicator of a lesion’s aggressiveness. An abrupt transition from normal to abnormal is a feature of benignancy. A wide transition is a feature of malignancy. The zone of transition is a direct reflection of the lesion’s aggressiveness and the response of the host bone to the lesion infiltration
FIG 13-4 Periosteal reaction of bone. A, Thin lamellar. B, Thick lamellar. C, Cortical buttressing (arrows). D, Codman triangles (arrows). E, Aggressive lamellar. F, Hair-on-end spiculated.G, Sunburst. Patterns A through C are associated with benign lesions of bone. Patterns D through G are associated with aggressive lesions of bone (e.g., Ewing sarcoma and osteosarcoma). From Juhl JH, Crummy AB: Paul and Juhl’s essentials of radiologic imaging, ed 6, Philadelphia, 1993, JB Lippincott.
What does a sunburst periosteal reaction indicate?
Skull lesion with a sunburst aggressive periosteal reaction (arrows). Courtesy Steven P. Brownstein, MD, Springfield, NJ.
Why is margination and zone of transition linked?
Margination describes the presence and thickness of the rim around the lesion. Malignant tumors typically are nonmarginated, a feature of their wide zone of transition (Figs. 13-8 and 13-9). Conversely, a lesion is most likely benign if surrounded by a sclerotic rim of varying thicknesses producing a narrow zone of transition. The presence of a thick margin is always accompanied by a short zone of transition and represents an attempt of the host bone to surround and limit a lesion’s growth. However, a short zone of transition is not always accompanied by a thick margin (e.g., giant cell tumor). The zone of transition should not be used as the sole criteria for determining the aggressiveness of the lesion. Even a well-marginated lesion can prove to be malignant in selected clinical circumstances.
For example, a painful lesion presenting with a narrow zone of transition in a 60-year-old patient who has a previous history of a primary tumor should be considered bone metastasis until proved otherwise.FIG 13-8 Margination of bone lesions. A, Thick. B, Thin. C, Absent. A to C demonstrate a short zone of transition between normal bone and the lesion. D, Ill-defined. Demonstrates a long zone of transition between normal bone and the lesion. A long zone of transition is most often associated with an aggressive lesion. From Juhl JH, Crummy AB: Paul and Juhl’s essentials of radiologic imaging, ed 6, Philadelphia, 1993, JB Lippincott.
What is the second most common primary bone tumor in cats after osteosarcoma?
periosteal osterosarcoma (a.k.a. juxtacortical osteosarcoma)
Growth arrest lines are caused by?
change in rate of growth in immature animals, may be dietary changes or systemic illness. They are well defined, horizontal lines of increased opacity in a long bone diaphysis. Most commonly in the femur and bilateral.
Hypertorphic Osteodystrophy (HOD) is caused by what?
What happens to the bone?
How long does it last?
Systemic dz of unknown origin (distemper, nutrition issues, etc.)
It is usually self limiting
Panosteitis (eosinophilic panostitis) is self liminting myelosclerotic dz which means what?
what are the breed and sex and age predilections?
obliteration of the marrow cavity of long bones
GSD and Bassetts
usually 4-12 m (can be 2m-7 yrs)
What is joint effusion?
increase in intrA-cellular fluid
Skyline view of the patella demonstrating a large joint effusion as marked by the arrow.
What radiographic sign can you look for with joint effusion?
A schematic drawing showing thesail sign which represents an effusion
What is eburnation?
A rim of compact bone normally present near joint surface and should not be confused with osterosclerosis due to disease. Bone looks like ivory mass
What is endrochondral ossification?
Endochondral ossification is the other majory embryonic process of bone formation. This is a process that uses hyaline cartilage as the model for long bone formation. A good way to remember the difference between endochondral and intramembranous ossification is to pay attention to their names. Remember the Greek word root for cartilage is chondr/o.
Here are the events that occur during this process in short; you can get a more detailed explanation in the video below:
1) Collar formation: periosteum forms around a piece of hyaline cartilage. Then the osteogenic cells (stem cells) differentiate (specialize) into osteoblasts. The osteoblasts then secrete their organic fibers (proteins) on the outside of the cartilage. Remember that these condensed fibers are called the osteoid. The end result of this is the formation of a bony collar on the outside of the cartilage.
2) Cavity formation: while step #1 occurs the cartilage in the center of the model begins to ossify (form into bone). This centered cartilage is called the primary ossification center. The calcification/hardening of the center makes the inner cartilage impermeable to the diffusion of nutrients. As a result the inner cartilage starts to deteriorate and cavities begin to form.
3) Vascular invasion: eventually the vessels that are within the periosteum will pass through the lamellar (compact bone) bony collar and invade the inner cavity of the cartilage model. The hole that the vessels poke through are called the nutrient foramen. Many other components enter through the nutrient foramen such as nerves, lymphatics, osteoclasts, osteoblasts, nutrients etc. The remaining cartilage is broken down by osteoclasts and the osteoblasts secrete their osteoid forming trabaculae (spongy bone).
4) Elongation: as blood vessels, osteoclasts, and osteocytes continue to invade the bone the shaft (diaphysis) will start to elongate. As a result the medullary cavity (hollow inner cavity) is formed and the diaphysis will slowly continue to lengthen during embryonic development. Also, vessels bud into the hyaline cartilage at the ends (epiphysis) of the long bones forming what are called secondary ossification centers.
5) Epiphyseal ossification: the events here are almost identical to #3 except instead of forming compact bone spongy bone is formed. Also, hyaline cartilage is left on the ends of the bones (called articular cartilage) and the epiphyseal plates (growth plates) are also formed. The articular cartilage and epiphyseal plates are the only remains of the original hyaline cartilage model.
(Light micrograph of epiphyseal plate showing endochondral ossification: healthy chondrocytes (top) become degenerating ones (bottom), characteristically displaying a calcified extracellular matrix).
What symptoms are associated with Chinese Shar-Pei fever syndrome? Why is it something to look for in musculoskeletal disorders?
Fever and recurring episodes of swelling of the tarsi. It is associated with renal amylodsis. Affects joints as an "arthritis".
Degenerative Joint Dz for the shoulder- can be idiopathic or secondary to a previous trauma, OCD, infection, immune-mediated dz. Lesons are best seen with a _____ radio graph.
The chronic irritation of synovium leads to nodular cartilaginous metaplasia in the scapulohumeral joint or biciptial tendon bursa. Nodules may remain and adhear to synovium or break off and become free fragments. What is this process due to?
Tendon damage may result from acute or repetitive trauma, inflammation (tenosynovitis), or entrapment of free fragment in joints is called?
Ununited anconeal process develops from what?
a separate ossification center in most medium and large breed dogs and normally fuses with proximal ulna b/f 20 weeks (22 in GSD)
What is the most common disorder with ebow dysplasia?
Fragmented medial coronoid process.