Bones Joints And Soft Tissue Flashcards
(40 cards)
What is the incorrect naming associated with bone inflammation, and why is it considered incorrect?
The term “osteitis” is often incorrectly used to describe bone inflammation. True osteitis refers to an inflammatory condition affecting the bone, but many conditions labeled as osteitis actually involve bone destruction or infection rather than true inflammation.
What is the cause and structural appearance of bone with haphazard trabecular formation?
The cause of haphazard trabecular formation is often unknown, but it can be seen in conditions such as Paget’s disease or fibrous dysplasia. The bone appears structurally weak, with disorganized and irregular trabecular patterns.
How does the periosteum respond to various bone pathologies, and what are the implications?
The periosteum responds by forming new bone, a process known as periosteal reaction. This can indicate infection, trauma, or neoplastic conditions. Radiographically, this new bone may present as Codman’s triangle or onion skin appearance.
Describe the stages of bone formation in pathological conditions.
Bone formation begins with a cartilage mold (endochondral ossification) or directly on a fibrous scaffold (intramembranous ossification). In pathologies like osteomyelitis, abnormal bone formation may be seen as involucrum, sequestrum, or cloaca.
What histological features indicate dead bone, and how can it be differentiated from viable bone?
Dead bone, or sequestrum, appears as necrotic, acellular, and paler tissue under the microscope. There is a loss of osteocytes in lacunae and often a surrounding zone of granulation tissue or pus in cases of infection.
What are the defining clinical and radiographic features of acute biogenic bone infection?
Acute biogenic bone infection presents clinically with pain, swelling, and erythema. Radiographically, it may show well-defined lytic lesions with periosteal elevation. The infection is typically pyogenic, caused by bacteria like Staphylococcus aureus.
Why are immunosuppressed patients at higher risk for chronic bone infections, and what pathogens are common in these cases?
Immunosuppressed patients have a reduced ability to mount an effective immune response, leading to persistent infections. Common pathogens include Pseudomonas aeruginosa, Mycobacterium tuberculosis, and fungal organisms such as Aspergillus.
What is the characteristic radiographic appearance of chronic osteomyelitis?
Chronic osteomyelitis may show mixed radiolucent and radiopaque areas with poorly defined edges. Sequestrum (dead bone) may be present as a dense, radiopaque segment, while involucrum appears as new bone formation surrounding the sequestrum.
What are the histological findings associated with chronic bone infections, and how do they differ from acute infections?
Chronic infections show necrotic bone, chronic inflammatory infiltrates (lymphocytes, plasma cells), and fibrous tissue. In contrast, acute infections have more neutrophilic infiltration and less organized fibrous tissue.
What is involucrum, and how does it form in response to bone infection?
Involucrum is new bone that forms around an area of sequestrum to wall off the infection. It develops as a periosteal reaction to contain and isolate the infected or necrotic bone segment.
How can the histological appearance of osteomyelitis aid in determining the stage of infection?
Acute osteomyelitis presents with abundant neutrophils and purulent exudate, while chronic osteomyelitis shows necrotic bone, fibrous tissue, and lymphocytic infiltrates. Granulation tissue and involucrum formation indicate a chronic stage.
Why is identifying the etiologic agent crucial in bone infections, and what diagnostic methods are used?
Identifying the etiologic agent allows for targeted antimicrobial therapy. Diagnostic methods include bone biopsy, culture, PCR testing, and histopathological examination.
What are the key clinical signs of osteomyelitis in pediatric versus adult patients?
In children, osteomyelitis typically affects long bones and presents with fever, pain, and swelling. In adults, it more commonly affects the vertebrae and is often associated with underlying conditions such as diabetes or vascular insufficiency.
How does trabecular structure differ in conditions like osteoporosis versus osteomyelitis?
In osteoporosis, trabecular bone appears thinned and porous, increasing fracture risk. In osteomyelitis, trabeculae may be disrupted by necrotic areas and reactive bone formation.
What is a periosteal reaction, and what are the common radiographic patterns observed?
A periosteal reaction is new bone formation in response to irritation of the periosteum. Common patterns include lamellated (onion skin), solid, sunburst, and Codman’s triangle, depending on the severity and duration of the pathology.
What is the difference between sequestrum and involucrum in bone infections?
Sequestrum is necrotic, devitalized bone that becomes isolated from healthy tissue. Involucrum is the reactive new bone that forms around the sequestrum in an attempt to wall off the infection.
What complications can arise from untreated chronic osteomyelitis?
Complications include sinus tract formation, pathological fractures, septicemia, amyloidosis, and squamous cell carcinoma arising in chronic draining sinuses.
How does fibrous dysplasia differ radiographically from Paget’s disease?
Fibrous dysplasia shows a “ground-glass” appearance with poorly defined borders, while Paget’s disease presents with mixed lytic and sclerotic areas, cortical thickening, and bone expansion.
Why is biopsy important in differentiating infectious versus neoplastic bone lesions?
Biopsy provides definitive histological evidence, distinguishing between infection (inflammatory cells, necrosis) and neoplasia (atypical cells, malignancy markers).
What are the typical treatment strategies for chronic osteomyelitis?
Treatment includes long-term antibiotic therapy, surgical debridement, and, in severe cases, resection of necrotic bone and reconstruction.
What are the primary differential diagnoses for bone lesions with a mixed radiolucent and radiopaque appearance?
Differentials include chronic osteomyelitis, fibrous dysplasia, Paget’s disease, and ossifying fibroma.
What are the hallmark clinical signs of acute osteomyelitis in pediatric patients?
Fever, localized pain, swelling, erythema, and refusal to bear weight or use the affected limb.
What is the preferred imaging modality for diagnosing chronic osteomyelitis and why?
MRI is preferred for chronic osteomyelitis as it provides detailed soft tissue and bone marrow evaluation, identifying sequestrum and involucrum more effectively than X-ray.
Describe the clinical presentation of Paget’s disease of bone.
Paget’s disease presents with bone pain, deformities, increased head size, bowing of the legs, and hearing loss due to skull involvement.
