Overview Osteoarthritis (OA) was previously thought to be a normal consequence of aging, leading to the term “degenerative joint disease.” However, it is now realized that osteoarthritis results from the interplay of multiple factors, including joint integrity, genetics, local inflammation, mechanical forces, and cellular and biochemical processes. Pathological changes include joint space narrowing, damage of articular cartilage, subchondral sclerosis and bone spurs/cysts.
Arthritis: Inflammation of a/multiple joints
Arthropathy: Joint pathology, any disease of the joint
Arthrosis: a term for a degenerative disease of the joint where the cartilage lining the joint erodes over time. Usually used for osteoarthritis.
Osteoarthritis: is a degenerative condition that mostly affects the hands, spine and joints such as hips, knees and ankles, and usually gets worse over time.
Rheumatoid arthritis: a chronic progressive disease causing inflammation in the joints and resulting in painful deformity and immobility, especially in the fingers, wrists, feet, and ankles. It is
The knee joint is a synovial joint, in that it is encapsulated by the synovial membrane which produced synovial fluid. As the knee is a modified hinge joint it is structured to perform two principal actions, flexion (bending) and extension (straightening). The muscles which act at the knee are predominantly the quadriceps (extension) and the hamstrings (flexion). The knee can also do a bit of internal and external rotation.
The knee joint is made up of three main bones:
Cartilage The ends of the bones are covered by articular cartilage. Between these bone articulation there is also the meniscus, another type of cartilage. The menisci are C-shaped fibrocartilaginous disks in the knee (lateral more O-shaped)
Most commonly presents in patients over 40 years of age
|Remember Septic arthritis is not really a differential of osteoarthritis, but should be ruled out with any monoarthritic presentation|
Advanced Investigations to rule out differentials
|Synovial fluid analysis|
|Aetiology||Colour and Clarity||WBC (mm³)|
|Normal||Normal||Clear and transparent||<200|
|Non-Inflammatory||Osteoarthritis||Yellow and transparent||0 to 2000|
|Inflammatory||Gout||Yellow and traslucent-opaque||2000-100,000|
|Septic||Bacteria||Yellow/green and opaque||>25,000 - >100,000|
|Haemorrhage||Trauma||Red and Bloody||200-2000|
|Remember The psychosocial evaluation should include an assessment of coping mechanisms, such as activity avoidance and denial, and of symptoms of depression|
|Remember Gastroprotection with PPI if on long term NSAIDs|
|Pharmacology NSAIDs inhibit COX1/COX2, enzymes responsible for converting arachidonic acid to Prostagladins, ThromoxaneA2. Prostaglandins promote inflammation, fever and pain. Thromboxane A2 causes platelet aggregation (blood clotting). Side effects: Increased BP, Dyspepsia, Peptic ulcer, duodenal ulcer, liver damage (rare and long-term), acute kidney injury, tinnitus (high-dose) and allergy. Contraindications: Pre-existing renal dysfunction, cardiac failure, severe hepatic dysfunction, history of GI bleeding, allergy, elderly >65|
|Indications for Knee Replacement|
|Conservative treatment has failed|
Complications with Joint Replacement Surgery
Prognosis Knee replacement is inevitable with patients with painful osteoarthritis. Knee replacements can last from 5-20 years depending on the activity level of the patient.