Apex of patella

The patella resembles a small triangle with the apex of patella pointing downward. The apex, located at the bottom, is the opposite side of the base, which forms the top border of the patella. The majority of the patella's posterior surface articulates with the lower femur, except for the non-articular back of the apex. Below, the apex of patella connects with the ligamentum patellae (or the patellar ligament).

Directly behind and below the apex, there is a substantial fat pad called the infrapatellar fat pad, also known as Hoffa's fat pad. It is snugly positioned between the apex and the neighboring bones—the lower femur and the upper tibia.

The infrapatellar fat pad is attached to the apex of patella and the ligamentum patellae at the front, as well as various knee ligaments and the periosteum of the proximal tibia at the back. Acting as a protective cushion, the fat pad separates the kneecap from the underlying shin and thigh bones. However, in some cases, the infrapatellar fat pad may become impinged, leading to pain and swelling, commonly referred to as infrapatellar fat pad syndrome.