Knee Osteoarthritis

Knee osteoarthritis (OA) is a whole-joint disease that causes activity-related knee pain, stiffness and loss of function, and it is a leading cause of chronic knee pain and disability in adults.

The medial tibiofemoral compartment is affected most often, followed by the patellofemoral and lateral compartments. Current NICE osteoarthritis guidance makes it a clinical diagnosis in people aged 45 or over with activity-related joint pain and either no morning stiffness or stiffness lasting no longer than 30 minutes.

The knee has 3 compartments: medial tibiofemoral, lateral tibiofemoral and patellofemoral. Hyaline cartilage covers the joint surfaces, the menisci spread load, and the cruciate and collateral ligaments, capsule and surrounding muscles give stability.

OA affects the whole joint, not just the cartilage:

• •Cartilage loss with subchondral sclerosis and osteophytes
• •Low-grade synovitis, which drives flare pain
• •Meniscal degeneration, capsular thickening and ligament laxity
• •Weakness of the muscles around the joint, particularly the quadriceps

The medial compartment carries the most load and is affected most often, typically with varus alignment.

Risk factors:

• •Obesity, a major modifiable risk factor
• •Previous meniscectomy, ACL rupture or intra-articular fracture
• •Malalignment
• •Inflammatory arthritis