Module 6: BOne: Osteomyelitis, Pott's, Osteoarthritis, RA Flashcards
First topic to discuss is Osteomyelitis, what is this?
Inflammation of Bone or bone marrow
- -implies infection
- -stages acute to chronic
What is the etiology for osteomyelitis?
Seen in young and elderly (M:F = 2:1)
- -most common organism is S. Aureus
- –GU infection, IVDA: E. coli, Klebsiella, and Pseudomonas
- -Direct Inoculation = mixed bacterial
- –Neonates = H. influenza, Group B Strep
- -Sickle Cell Anemia = Salmonella
What is the most common location for osteomyelitis?
Long tubular bones (femur, tibia, humerus) Vertebral bodies (most commonly lumbar)
What is the pathogenesis for osteomyelitis?
Begins in metaphysis b.c nutrient arteries terminate in venous sinusoids (ideal for bacterial seeding) and decreased O2 tension inhibits phagocytosis — formation of abscess within medulla and under periosteum and bone necrosis
- -bone necrosis = 48 hours
- -progressive ischemia leads to segmental bone necrosis = sequestrum
- surrounded by viable new bone (involucrum) formation
Why is acute osteomyelitis worse in young children or infants?
Abscess gets out in the periosteum aka extending into the joint space — extensive articular damage —permanent disability
How does acute osteomyelitis present?
Fever Tenderness Swelling Purulent discharge Neutrophilia Leukocytes
What do you find on x-ray for osteomyelitis?
Radiolucency with sclerotic bone rim (irritated periosteum lays down new bone)
5-25% of acute osteomyelitis do not resolve and progress into chronic osteomyelitis, what is the pathology?
Chronic inflammation
Resorption of dead bone
Deposition of woven bone (immature bone)
Brodie abscess: Intracortical abscess
Sclerosing OM of Garre: Jaw: Extensive new bone obscuring the underlying bone
Next moving on to Pott’s Disease also called TB osteomyelitis, what is the etiology?
From hematoegnous spread of tuberculosis to chronic bacterial infection
–less commonly spread through direct contact
What is the pathogenesis for Pott’s Disease?
Destroys the intervertebral discs first — then damages the vertebral bodies
–spreads through medullary cavity causing extensive necrosis
What vertebrae are favored in kids vs adults who have Pott’s Disease?
Kids: Thoracic Vertebrae
Adults: Lumbar vertebrae
What kind of patients is Pott’s disease seen in?
Seen in miliary TB usually
but still can be seen in immunocompetent ppl
What is the presentation of Pott’s Disease?
Low back pain, parasthesias and paralysis
Kyphosis and scoliosis
Spinal cord compression – cauda equine compression = paralysis
What do you see on biopsy for patients with Pott’s Disease?
Immunocompromised = acid fast bacilli Immunocompetent = caseating granuloma
What are the complications of Pott’s?
Immunocompetent: granuloma can take over bone marrow — myelophisic anemia (Normocitic Normochromic Anemia)
Spinal Cord Compression
Psoas Abscess: cold abscess due to minimal inflammatory response (no spiking fevers seen in normal abscess)
Amyloid deposition (Eosinophilic glassy material) in the kidney
The next topic is Osteoarthritis, what are pre-disposing factors?
Most common joint pathology
most important risk factor = age
other risk factors = recurrent trauma and obesity
What joints are affected in Osteoarthritis?
Hip, Knee and Spine (cervical and lumbar)
Weight bearing joints
Can also affect DIP and PIP (typing alot)
What is the pathogenesis for osteoarthritis?
Degenerative Joint Disease: no inflammatory response
–enzymatic breakdown of articular cartilage (due to wear and tear)(fibrillations) — cracks – bone on bone eburnation — deeper cracks that dislodge as joint mice (have a central core of necrotic bone) — leakage of synovial fluid — subchondral cysts