Updated December 16, 2014.
The quadriceps tendon is the large tendon just above the kneecap. The quad tendon is part of the extensor mechanism of the knee that includes the quadriceps muscle, the quad tendon, the kneecap (patella) and the patellar tendon. It is the extensor mechanism that allows us to straighten our knee or perform a kicking motion. When the quadriceps muscle (thigh muscle) contracts, force is transmitted through the quadriceps tendon, across the patella (kneecap), through the patellar tendon, and the knee is straightened.
The quadriceps tendon is a thick, strong tendon that can withstand tremendous force. A tendon is a structure that attaches a muscle to bone. The force of muscle contraction is transmitted through the tendon to move the bone.
People who injure the extensor mechanism may tear the patellar tendon, fracture the kneecap, or tear the quad tendon. All of these injuries have similar treatments and rehabilitation plans.
Quad Tendon Rupture
Partial quad tendon injuries can occur in association with athletic activities or active lifestyles. These symptoms may cause gradually increasing pain over the kneecap and may be misdiagnosed as a kneecap problem.
Complete quadriceps tendon tears are unusual injuries. They most often occur in people over the age of 40, and often in people who have systemic medical conditions that can cause weakening of the tendon.
If the tendon is completely ruptured, the patient will be unable to straighten the knee without help and he or she will be unable to perform a straight leg raise.
Most patients will have swelling of the knee and your doctor will be able to feel the torn tendon just above the kneecap. X-rays can help your doctor determine if the kneecap was damaged. While an MRI is usually not necessary, your doctor may order the test to evaluate for other damage within the knee joint.
Treatment of a Quadriceps Tendon Rupture
Partial tears of the quadriceps tendon can usually be managed with non-surgical treatments. These treatments may include the use of a knee brace or immobilizer, ice application, anti-inflammatory medications, physical therapy, and rest from athletic activities.
Complete tears of the quadriceps tendon require surgical intervention to regain strength in the extremity. Surgery is usually done within a few weeks of the injury, as some reports have shown that delayed treatment may lead to less successful results. Surgery is performed to suture the torn tendon back to its attachment on the patella (kneecap). In order to accomplish this, your surgeon will use a drill to make holes (tunnels) in the patella, and then loop sutures through these tunnels to pull the tendon to the bone.
Following surgery, most surgeons use a brace to protect the repair. Patients may use crutches, although weight can be placed on the leg as long as the knee is kept straight. Many surgeons allow early range of motion exercises, but this should be done under the supervision of a physical therapist. The brace can usually be discontinued after 3 months, and sports resumed in 4-6 months.
Sources:
Ilan DI, et al. "Quadriceps Tendon Rupture" J Am Acad Orthop Surg May/June 2003 vol. 11 no. 3 192-200.