The patellar ligament, alternately known as the patellar tendon, is a band of connective tissue that links the kneecap, or patella, to the tibia bone in the lower leg. Located just under the knee, it is roughly four inches long and about an inch wide (10.16 cm long and 2.54 cm wide)and is flat and fibrous. This ligament is necessarily both strong and flexible, as it helps to maintain the structural bond that connects the lower leg to the knee joint while also withstanding a great deal of force on the knee from the simplest of movements.
Technically a continuation of the quadriceps femoris tendon, which connects the four muscles of the quadriceps on the front of the thigh with the knee joint, the patellar ligament arises from the two sections of that tendon that run vertically along either side of the patella and converge just beneath it to form the ligament. It originates on the underside of the patella and attaches several inches below to the tuberosity of the tibia bone. This is the bony protrusion, one which can be felt just below the knee joint, on the top front surface of the tibia, the largest bone of the shin. The patellar ligament also shares some common fibers with the quadriceps femoris tendon that runs vertically across the anterior surface of the kneecap.
Injuries to this tissue are common and range from repetitive stress injury (RSI) like tendinitis to acute injuries like tears, which are typically the result of impact. Patellar tendinitis is common among distance runners, cyclists, and athletes whose sport requires a lot of jumping, as repeated stress on the ligament can over time develop into painful inflammation and even ruptures. Recommended treatment for patellar tendinitis, which is felt as pain just below the kneecap, is the RICER formula: rest, ice, compression, elevation, and referral to a doctor for medical treatment. Rest means avoiding any activities that stress the area further, and as with icing, recommendations vary for the duration and frequency of treatment, depending on the degree of injury. As such, it is recommended to consult a doctor for specific instructions.
Certain high-impact movements, like landing from a jump, can also result in acute injury to the patellar ligament, such as a strain or full-blown tear. When the quadriceps are contracted forcefully to extend the knee, as in standing up too quickly from a squat position, or to decelerate the landing of a jump, the ligaments at the knee joint, which do not stretch as muscle tissue does, may not be able to withstand the excessive force. The result may be a strain, or overstretching of the tissue, a partial tear, or a full tear. Depending on the severity of the injury, recovery can take several weeks or several months. As with tendinitis, RICER is recommended as soon as possible following the injury.