Final answer:
The absence of the patella would lead to a decreased moment arm for the knee extensors, reducing their ability to generate force and making knee extension less efficient.
Step-by-step explanation:
The patella, or kneecap, plays a critical role in the biomechanics of the knee joint, particularly in enhancing the leverage of the knee extensors by increasing the angle at which the patellar tendon acts. The extensors, which include the quadriceps muscle group, are responsible for straightening the knee. Without the patella, the moment arm of the knee extensors is reduced, leading to a decrease in their ability to generate force effectively.
Therefore, if someone lacks a patella, they are likely to experience decreased efficiency in knee extension due to a decreased moment arm of the knee extensors. This can make activities like climbing stairs or standing from a seated position more difficult.