Cartilage biology Flashcards
Healthy cartillage is made up of what components?
Proteoglycans, type II collagen and water.
How do proteoglycans support healthy cartillage?
Exerts swelling, resists compression.
How does type II collagen support healthy cartillage?
Provides structural support due to high tensile strength.
Chondrocyte function
Producer and degrader of cartilage matrix.
Chondrocyte properties
Metabolically active, adapted to low oxygen environment and no cell division after adolescence.
What is aggrecan?
Proteoglycan.
What glycosaminoglycan chains are present in aggrecan?
Hyaluronan, keratin sulfate and chondroitin sulfate.
Function of glycosaminoglycan chains in aggrecan?
Highly negative charge. Attracts sodium and causes water to move in which results in swelling pressure that resists compression.
What breaks down aggrecan?
Matrix metalloproteinases and aggrecanases.
What is articular cartilage?
Hyaline cartilage found in joints.
Intrinsic anabolic and anti-catabolic factors for articular cartilage in joints?
Tissue inhibitor of metalloproteinases. Growth factors.
Extrinsic anabolic and anti-catabolic factors for articular cartilage in joints?
Hormones and drugs
What maintains cartilage thickness?
Mechanical load.
What does a loss of cartilage in the joints result in?
Osteoarthritis.
What is the largest factor that affects load on joint?
Bodyweight.
What are the molecular changes present during osteoarthritis?
Proteoglycan fragmented by aggrecanases. Collagen broken down by collagenases (MMP).
What early changes in cartilage would be present in early osteoarthritis?
Loss of proteoglycan in superficial zone leads to fibrilation.
What late changes in cartilage would be present in late osteoarthritis?
Fissuring deep into cartilage matrix, loss of cartilage thickness, formation of osteophytes and bone cysts. Synovial inflammation.
What are osteophytes?
Bony lumps.
What are bone cysts?
Fluid filled holes in bone.
What is synovial inflammation?
Inflammation of synovial membrane.
OA risk factors?
Age, obesity, joint injury, stickler syndrome.
How would you diagnose OA?
Joint pain, joint stiffness and X ray for staging and treatment planning.
Where does hand osteoarthritis occur?
Distal interphalangeal joint, proximal interphalangeal joint and trapeziometacarpal joint (base of thumb OA).
How to manage OA?
Exercise, weight management, non steroidal anti inflammatory drug.
OA treatment?
Total joint replacement. Trapeziectomy
