Psoriasis: The most common skin disorder that also affects the joints, including the knees, is psoriasis. Although certainly not all patients with psoriasis will develop joint problems, psoriatic arthritis may cause knee pain and swelling. ...Read more.
Definition of accident. 1  1a : an unforeseen and unplanned event or circumstance Their meeting was an accident.b : lack of intention or necessity : chance They met by accident rather than by design.
A collision or crash is an event in which two or more bodies exert forces on each other for a relatively short time. Although the most common colloquial use of the word collision refers to incidents in which two or more objects collide, the scientific use of the word collision implies nothing about the magnitude of the force.