Why did my knee and lateral condyle swell for several days after I kneel on that knee?

Swelling in the knee and lateral condyle after kneeling could be due to inflammation caused by trauma or pressure on the joint, leading to irritation of the surrounding tissues, such as the bursae or synovial membrane. This can result in an accumulation of fluid (effusion) as the body responds to the injury. Additionally, if there was any underlying condition, such as Arthritis or a previous injury, this could exacerbate the swelling. It's advisable to rest, ice the area, and consult a healthcare professional if the swelling persists or worsens.