General rheumatology Flashcards
What are the three types of joint?
Fibrous
Fibrocartilaginous
Synovial
What is a primary cartilaginous joint? Where are these found in the body?
A joint at which the bones are united by a plate of hyaline cartilage so that the joint is immovable and strong. These joints are temporary in nature because after a certain age the cartilaginous plate is replaced by the bone. Examples of this type of joint are between the epiphyses and diaphysis of a growing long bone, the costochondral joint and the first chondrosternal joint
What is a secondary cartilaginous joint? Where are these found in the body?
Known as “symphyses”. Fibrocartilaginous and hyaline joints, usually occurring in the midline.
Examples in human anatomy are the manubriosternal joint intervertebral discs, and the pubic symphysis
What is synovium?
Synovium is the lining of the joint capsule. It is a few cells thick and is vascular. Its surface is smooth and non-adnerent and is permeable to proteins and crystalloids. As there are no macroscopic gaps, it is able to retain normal joint fluid even under pressure. Tendon sheaths and bursae are also lined by synovium
What cells make up the synovium?
Macrophages and fibroblast-like synoviocytes
How is cell-to-cell interaction in the synovial layer mediated?
Cadherin-II (a transmembrane protein)
What is the tole of synoviocytes in the synovial layer?
They release hyaluronan fluid into the joint space which helps to retain fluid in the joint
What is synovial fluid?
A highly viscous fluid secreted by the synovial cells which has a similar consistency to plasma.
What is the part of a bone which directly contributes to the joint called?
the epiphyseal bone
What is the shaft of a bone called?
the metaphysis
Describe the structure of epiphyseal bone. What is the clinical significance of this?
Epiphyseal bone is highly vascular and comprises a light framework of mineralized collagen enclosed in a thin coating of tougher, cortical bone.
This is clinically important as the ability of this structre to sithstand pressure is low and it collapses and fractures when the normal intra-articular covering of hyaline cartilage is worn away as in osteoarthritis. Loss of hyaline cartilage also leads to the abnormalities of bone growth and remodelling typical of OA.
What is hyaline cartilage? Describe it’s structure
Hyaline cartilage forms the articular surface of joints. It is avascular and relies on diffusion from synovial fluid for its nutrition. It is rich in type II collagen that forms a meshwork enclosing giant macromolecular aggregates of proteoglycan.
What is the role of a ligament?
To stabilise a joint. They are variably elastic and this contributes to the stiffness or laxity of joints
What is the role of tendons?
Tendons are inelastic. They transmit muscle power to bones.
What is an enthesis?
The point where a tendon or ligament joints a bone. May be the site of inflammation
Describe the structure of collagen
Collagens consist of three polypeptide (alpha) chains wound into a triple helix. Every third polypeptide is glycine.
What is elastin?
An insoluble protein polymer, secreted as tropoelastin, which is the main component of elastic fibres
What is the function of proteoglycans?
They bind extracellular matrix together, retain solube molecules in the matrix and assist with cell binding
What is the difference between arthralgia and arthritis?
Arthralgia describes joint pain when the join appears normal on examination
Arthritis is the term used when there is objective evidence of oin inflammation (swelling, deformity or an effusion)
What are the likely causes of joint pain in young men?
Reactive arthritis
Ankylosing spondylitis
What are the likely causes of joint pain in young women?
Systemic lupus erythematosus
Rheumatoid arthritis
Sjogren’s syndrome
What are the likely causes of joint pain in young adults regardless sex?
Psoriatic arthropathy
Enteropathic Arthropathy
What are the likely causes of joint pain in middle-aged men?
Gout
What are the likely causes of joint pain in middle-aged women?
Rheumatoid arthritis