Osteoporosis and Osteoarthritis
(Etiology, Pathogenesis, Clinical Manifestations)
Definition
Osteoporosis is a systemic skeletal disease characterized by decreased bone mass and deterioration of bone microarchitecture, leading to increased fragility and risk of fractures.
Pathogenesis
- Imbalance between bone resorption and formation:
- Osteoclast activity > Osteoblast activity.
- Estrogen deficiency (postmenopausal):
- ↑ osteoclast activity → bone resorption.
- Age-related changes:
- ↓ osteoblast function, ↓ calcium absorption, ↑ PTH.
- Net result:
- Loss of trabecular and cortical bone → weakened bone structure and ↑ risk of fractures (esp. hip, spine, wrist).
Clinical Manifestations
- Often asymptomatic until fracture occurs.
- Common fractures:
- Vertebral compression fractures → back pain, height loss, kyphosis.
- Hip fractures (femoral neck).
- Distal radius fracture (Colles’ fracture).
- Stooped posture, reduced mobility.
Definition
Osteoarthritis is a chronic, degenerative joint disease characterized by progressive loss of articular cartilage, subchondral bone remodeling, and formation of osteophytes, leading to joint pain and stiffness.
Pathogenesis
- Mechanical stress or aging → microtrauma to cartilage.
- Chondrocyte injury → imbalance in cartilage matrix synthesis and breakdown.
- Progressive cartilage loss → exposed subchondral bone.
- Subchondral bone sclerosis, osteophyte formation, and synovial inflammation.
- Leads to pain, stiffness, and reduced joint mobility.