1. The patella develops as a part of the quadriceps apparatus.
2. In the adult, it retains a close association with the muscle and with certain of the muscle fibers. Tendon fibers are directly attached to it.
3. It has to be separated from the muscle by sharp dissection which divides the muscular and tendinous insertions.
4. Removal of the patella in the rabbit is followed by degenerative changes in the articular cartilage of the patellar surface of the femur, but not by any apparent change in gait or in joint efficiency.
5. This suggests that the principal function of the patella is protective.
6. Removal of the patella is also followed by attempts at regeneration, which sometimes culminate in the development of a bony structure of appreciable size. In other cases, a fibrocartilaginous change takes place in the quadriceps tendon at the former site of the patella.
7. It is suggested that further investigation is necessary in the human subject, to determine the extent of the degenerative changes, before the operation is practised widely for conditions other than fracture or serious organic diseases of the bone itself.