Disc Lecture Flashcards
How much bigger should the IVF be in comparison to the nerve root that traverses it?
5-6x larger
What are the first trabeculae to go away when you lose vertebral bone density?
Horizontal trabeculae
What do the discs rely on for nutrition?
Diffusion
What is the distribution of blood supply to the disc?
50% from vessels of annulus
50% from vertebral endplates
What ensures that an even distribution of compressive stress acts on the vertebral bodies generating a tensile “Hoop Stress” in the surrounding annulus?
Nucleus Pulposus
What grade of the nucleus pulpous is a young, non-degenerated nucleus. There is a large “functional nucleus” in which the horizontal and vertical stresses are equal?
Grade 1
What grade of the nucleus pulpous is a mature disc indicative of 35-70 year olds in which the hydrostatic region shrinks?
Grade 2
What grade of nucleus pulposus is moderately degenerated with irregular stress profile indicating variable resistance to compression with a small or absent central hydrostatic region?
Grade 3
What grade of nucleus pulpous has a highly irregular and variable stress profiles and by an overall reduction in compressive stress and may have osteophytes?
Grade 4
What is the composition of the Nucleus Pulposus?
70-85% water, 20% collagen, 50% proteoglycan
What is the composition of the Outer Anulus?
50% water, 70% collagen, 10% proteoglycan
What type of collagen is typical of tensile structures like ligaments and is HIGHEST in the outer anulus?
Type I collagen
What type of collagen is typical of compressed tissues like articular cartilage and is HIGHEST in nucleus and ABSENT in outer anulus?
Type II collagen
How much fluid does the disc lose in the first hour of the morning?
90%
T/F: With normal aging, fibrous tissue replaces nuclear mucoid matrix, but the disc height is preserved and the disc margins remain regular
True
What is found in 100% of skeletons with individuals over 40?
Anterior and lateral margin vertebral body osteophytes
What are knobby excresences of the vertebral bodies indicative of?
Degenerative osteoarthritis
Who is most at risk for osteoporosis?
Post-menopausal women
T/F: Genetics may play a role in 60% of “back pain”
True
What are the 3 entities that describe primary disc pain?
Discitis
Torsion Injuries
Internal disc disruption (IDD)
What is a disc that is infected by bacteria introduced by needles used for discography?
Discitis
Axial rotation movements of the lumbar spine is limited to how many degrees?
1 degree
No evidence of torsional damage to the disc can be detected in how many degrees?
1-9 degrees
What actually tears during a torsional injury?
Circumferential tears of the anulus
What does 50Nm of extension, lateral flexion, and rotation do to lumbar compression?
extension = 800Nm of compression
Lat. Flexion = 1400Nm of compression
Rotation = 3000 Nm of compression
What is the cardinal pathological basis for discogenic pain?
Internal Disc Disruption
What percent of patients with LBP are suffering from Internal Disc Disruption?
40%
What is the definition of Internal Disc Disruption?
Degradation of the nucleus and the development of radial fissures that extend into the anulus
What is the weak link of the lumbar spine during compression?
Vertebral endplate
What are the criteria for diagnosing IDD?
Saline must reproduce pain
Grade 3 annular fissure on a CT
What are the Radial Fissure Grades?
Grade 0: no fissure
Grade 1: Fissure penetrates into inner 1/3 of annulus
Grad 2: Fissure penetrates into the middle of the annulus
Grade 3: Fissure penetrates into the outer 1/3 of the annulus
Grade 4: a Grade 3 fissure that spreads circumferentially around the annulus
What are a family of degradative enzymes in the nuclear matrix that chew up collagen?
Metalloproteinases
What induces the activity of metalloproteinases?
Vertebral Endplate fractures
What type of herniation involves less than 25% of disc circumference?
Focal Herniation
What type of herniation involves between 25% and 50% of disc circumference?
Broad-Based Herniation
T/F: The lower the pH, the more inflammation and fibrosis, and the greater the degree of pain
True
What is an inflammatory condition of the nerve root due to rupture of the annulus fibrosus and dissemination of disk fluid along the nerve root sheath
Chemical radiculitis
