C3-HC16 Flashcards
Number of disks in your intervertebral disk:
Number of disks in your intervertebral disk:
5 cervical disks
11 thoracic disks
4 lumbar disks
What is the function of your intervertebral disk?
It allows as to bear load and be flexibility.
How many degrees of freesdom does your intervertebral disk have? And large/small ROM?
It has 6 degrees of freedom (3 translational & 3 rotational), large range of motion (ROM) when all the functional spine units are taking in account.
The intervertebral disk consist of 3 parts:
nucleus pulposus (NP); gel, center of the disk lamellar annulus fibrosus (AF); outside of the disk, outer collagen fiber cartilage endplates (EPs); overlying NP and IAF
What is the Donan-Gibbs osmotic equilibrium?
Donan-Gibbs osmotic equilibrium: The nucleus has proteoglycans with lots of negative charges. They will attract all the cations (Na+) inside your body. So where you have lots of proteoglycans, you have a higher concentration of sodium than else where in your body. This will create a osmotic pressure and attracts water into the tissue. The tissue will swell till 90% water.
What is the Collagen lamellae?
They are inside the AF. If you go from the outside to the inside, there are many layers. Within each layer, you have collagen fibers aligned. These fibers alternate. The first layer is rotated 30 degrees to the left compared to the endplate, the second layer is rotated 30 degrees to the right, etc. Why is this ideal for the disk? In order to rotate: depending on which way you rotate to, the fibers gets stretched.
Low back pain:
? % point prevalence
? % chronic pain
- 12-30% point prevalence (30% of the people will experience low back pain somewhere in their life)
- Only 4% have chronic pain (is pain longer than 6 months)
- Socioeconomic burden. Why? It occurs in people who are working. This costs millions of euros per year.
Current treatments of IVD degeneration (IVDD):
Current treatments of IVD degeneration (IVDD):
○ Total disk replacement (TDR): take out the disk and replace it with an prosthesis.
○ Fusion: take out an disk and allow the bone to grow from vertebra to vertebra. Problem: now the 2 vertebras can’t move relative to each other. But you have 26 others in your body that can move, so fusing one is not such a big problem.
These treatments are for the very end-stage of the disease, when there is nothing else you can do; DDD score 8-15.
6 properties of the IVD:
- Harsher environment: It is the largest avascular (no blood vessels) organ > only on the very outside there are some vessels (see red in the picture). Therefore, it is difficult to get nutrients and oxygen.
- Diffusion > 7 mm
- 2% O2, low [glucose]; so hardly any energy for the cell to survive
- pH ±6.8-7.0; most cells will die in this low pH
- Hydraulic pressure (1-2 Mpa)
- High deformational strand (10-50%); the cells must be able to reduce their size
In the NP: high/low ...? metabolites acid nutrients oxygen glucose. In the vertebral: ?
In the NP: high metabolites & acid, low nutrients & oxygen & glucose.
In the vertebral: the other way around.
Notochordal cells:
Notochordal cells:
• Developing from embryo, these cells disappear everywhere except in the intervertebral disks (especially in the NP). When we become older, these cells do disappear a little, but there are still cells which have notochordal markers. Later on, also these cells disappear. This is the case for: humans, sheep, goat, cows, and horses.
• For pigs, cats, rabbits, rats, and mice this is not the case. They keep these cells when they get older and only lose them at the very end. These cells are really big.
• There are two types of dogs: the ones with short legs relative to their body, and with long legs. The dogs with small legs lose their notochordal cells (like us), the other dogs keep these cells (you can tell because their nucleus is more translucent and jelly). Dogs with short legs often have back pain.
