Which of the following is NOT a risk factor for osteoarthritis of the knee?

The choice of age 18 as a factor that is NOT associated with osteoarthritis of the knee reflects an understanding of the demographic that typically experiences this condition. Osteoarthritis is primarily observed in older adults, as the condition is associated with the wear and tear of joints accumulated over time. When individuals are younger, particularly at the age of 18, their joints have not yet undergone the significant stress or degeneration that can lead to osteoarthritis.

In contrast, factors such as heredity, gender, and joint overuse are all known to contribute to an increased risk of developing osteoarthritis. Heredity plays a role as genetic predisposition can influence cartilage durability. Gender is significant since statistics reveal that women are more likely to develop osteoarthritis, particularly after menopause, due to hormonal changes affecting joint health. Additionally, joint overuse, which can occur through repetitive activities or heavy physical labor, directly contributes to increased wear on the knee joints, elevating the likelihood of osteoarthritis as a person ages.

Thus, identifying age 18 as a non-risk factor highlights the importance of recognizing typical onset demographics for osteoarthritis while reinforcing the relevance of other established risk factors.