Patella is the largest seed bone in human body. The quadriceps femoris covered in front and extended downward to form patellar ligament, ending in embryonic tubercle. On both sides is the key membrane next to the skeleton. The articular cartilage surface is at the back, forming a bony joint with the femoral skin surface. Patella, together with its surrounding ligaments and aponeurosis, constitutes the middle knee device, which is a very important structure in lower limb activities.

Patella has an important biomechanical function in knee joint activities. If the bone is removed, the patellar ligament is closer to the activity center of the knee, shortening the lever arm that extends the knee. In this way, the quadriceps femoris needs 30% more muscle strength than normal to stretch the knee, which is unbearable for most patients, especially the elderly. Therefore, after bone fracture, it is necessary to restore its integrity as much as possible.

What are the causes of patella fracture?

Violence directly acts on the patella, such as kneeling when falling, and the patella directly hits the ground, resulting in fracture. Due to the strong traction of muscles, for example, in order to prevent falling to the ground, the quadriceps femoris contracts violently to maintain the stability of the body and tear the patella. Direct violence often leads to fractures; Muscle-driven violence often leads to patella transverse fracture. According to the posture and muscle tension at the time of injury, fractures can occur in the upper pole, middle pole and lower pole of patella.

Patella fractures mostly occur in young people. After the injury, the front of the knee was swollen and bruised, and the knee joint could not move. Examination can find tenderness in front of the patella, depression caused by fracture separation can be found in the early stage of injury, and the pain of squeezing the patella is aggravated. Due to blood in the joint, the floating patella test may be positive. Ortholateral X-ray film of knee joint can determine the location, type and degree of displacement of fracture, which is an important basis for choosing treatment methods.