Can anyone in medicine give me a definition of these two found in RA diagnosis?

Question

1 Subchondral cyst and cortical margin erosion's

2 Progressive erosive disease with joint destruction

3 In the neck it is important to look for instability that identifies danger to the spinal cord - especially, atlanto-axial and subaxial subluxation, and basilar settling

Thanks I am writing the research up and if I can't understand it then the person it is for won't.

Answer 1

Subchondral Cyst* ~

Benign unilocular lytic areas in the proximal end of a long bone with well defined and narrow endosteal margins. The cysts contain fluid and the cyst walls may contain some giant cells. Bone cysts usually occur in males between the ages 3-15 years.

Definition of Atlantoaxial

Atlantoaxial: Pertaining to the first and second cervical vertebrae which meet at a joint called the atlantoaxial joint.

The uppermost cervical vertebra (the atlas) rotates about the odontoid process of the second cervical vertebra (the axis). The joint between the axis and atlas is a pivot type of joint that allows the head turn.

Definition of Subluxation

Subluxation: Partial dislocation of a joint. A complete dislocation is a luxation.

Answer 2

1) Subchondral cyst formation is characteristic of osteoarthritis it is a fluid-filled sac that extrudes from the joint, consisting of thickened joint material (mostly hyaluronic acid, a substance found in normal joint fluid that serves to lubricate the joint).

2)speaks for itself

3)This is saying that it's important to look out for misaligned or partially dislocated vertebrae eg. cervical 1 & cervical 2 atlas and axis and below the axis

C1 is the Atlas supporting the skull and C2 is the Axis which it rotates on so the head can turn from side to side.

Presumably meaning that it would be easy in that case for the spinal cord to get severed

Atlantoaxial subluxation is the most common cause for pain in the upper neck, occiput, and forehead in patients with rheumatoid arthritis. Symptoms are aggravated by motion.

I would hope that the person in question is a medical person or they still wont understand it!