No! While more common with increasing age, arthritis and other rheumatic diagnoses can occur in in infants and children of any age!
Not always. Most all of us will develop wear and tear osteoarthritis as we age. Trauma to joint often accelerate the development of arthritis as does poor mechanical alignment. In other cases, even in very young age, arthritis can occur as an autoimmune disease, which means the body's immune system mistakenly attacks healthy tissue. This can begin even in childhood.