lecture 1 Flashcards
(26 cards)
What is osteonecrosis?
Death of bone due to loss of blood supply
Often affects hips, knees, shoulders and ankles; seen in people over 40 but can occur at any age.
What are common causes of osteonecrosis?
- Trauma (e.g., femoral neck fractures)
- Non-traumatic causes (e.g., steroids, alcohol, radiation, chemotherapy, sickle cell, SLE, HIV, pregnancy, organ transplants)
Trauma often affects the medial femoral circumflex artery.
What are the phases of AVN?
- Cell necrosis (6-48 hours)
- Healing response
Cell necrosis includes death of marrow cells and osteocytes; healing involves osteoclasts and creeping substitution.
What occurs during the healing response in AVN?
- Osteoclasts remove necrotic bone
- Creeping substitution - new bone laid down on dead trabeculae
This new bone is weak and prone to collapse, leading to flattening of the femoral head and secondary osteoarthritis.
What are symptoms of subchondral infarcts in AVN?
Pain on activity, later again at rest
Collapse of bone leads to arthritis.
What are medullary infarcts in AVN?
Often silent, but can transform to osteosarcoma, fibrosarcoma, or angiosarcoma
May function as Sequestra, predisposing patients to osteomyelitis and soft-tissue infections.
What is radiculopathy?
A conduction block in the axons of a spinal nerve or its roots
Can cause neurological loss, motor or sensory, and may or may not be associated with radicular pain.
What causes radiculopathy?
- IVD prolapse
- Degenerative diseases of the spine
- Fracture
- Malignancy
- Infection
These factors lead to nerve root compression.
What is radicular pain?
Pain from dorsal root ganglion irritation
Characterized by shooting or burning pain.
What does plexopathy affect?
Nerve plexuses
Includes branchial and lumbosacral plexuses.
What is neuropathy?
Localized peripheral nerve trunk pathology
An example is carpal tunnel syndrome.
What are the components of intervertebral disk structure?
- Nucleus pulposus - gelatinous core made of proteoglycans and water
- Annulus fibrosus - concentric rings of collagen
- End plates - interface with vertebral body
Type 1 collagen is on the outside, Type 2 on the inside of the annulus fibrosus.
What causes disc herniation?
Tears in the annulus, especially posterior
This leads to nucleus pulposus herniation, causing nerve root compression and an inflammatory response.
What are the types of disc herniation?
- Protrusion - contained
- Extrusion - through the annulus
- Sequestration - free fragment
These types differ by the extent of annulus involvement.
What are common sites for disc herniation?
- L4-L5
- L5-S1
Postero-lateral herniation compresses the ipsilateral nerve root, e.g., L5 root at L4-L5.
What is the blood supply to the intervertebral disk?
- Small vessels supplying the central disk until 8 years old
- In adults, blood supply is limited to outer ligamentous structures
The central disc obtains sustenance from diffusion across the end plates as it ages.
What can happen during the initiation and progression of herniation?
Initial fall can damage the disc; the tear waits for a weight-bearing flexion event to progress to frank herniation
Herniation can often remain unnoticed.
What are degenerative changes in the spine?
- Ligamentum flavum hypertrophy
- Disc narrowing
- Facet joint osteoarthritis - lumbar osteophytes
These changes contribute to spinal stenosis.
What is spinal stenosis?
Abnormal narrowing of spinal canal or foramen, compressing spinal cord or roots
Symptoms include neurogenic claudication, numbness, weakness, and urinary issues.
What are common characteristics of osteoporosis and compression fractures?
- Kyphosis
- Back pain
Bone spurs or osteophytes are hallmarks of spondylosis.
What are common types of tumors in the spine?
Most commonly metastatic from breast, lung, prostate
Lytic lesions are also seen in multiple myeloma.
What are common infections affecting the spine?
- Osteomyelitis
- Epidural abscess
- TB - Pott’s disease
- Herpes zoster
These infections can lead to caseous necrosis, joint fusion, and sequestra.
What is cauda equina syndrome?
Compression of nerves in cauda equina L2-S5
Most commonly due to large disc herniation, tumors, abscess, trauma, or stenosis.
