Tendons are strong cords of fibrous tissue that attach muscles to bones. The patellar tendon attaches the bottom of the kneecap (patella) to the top of the shinbone (tibia) and helps straighten your leg. Small tears of the tendon can make walking and using stairs difficult. A large tear is a disabling injury that usually requires surgery.
How common: This injury is rare (a very strong force is required to tear the tendon).
Average patient: 30-year-old recreational basketball player landing from a jump.
Cause: Direct impact to the front of the knee from a fall or other blow is a common cause of tears. Cuts are often associated with this type of injury. The patellar tendon usually tears when the knee is bent and the foot planted, like when landing from a jump or jumping up. A weakened patellar tendon is more likely to tear. Several things can lead to tendon weakness including inflammation (called patellar tendinitis), local corticosteroid injections used to treat patellar tendinitis, chronic renal failure, Rheumatoid arthritis, Diabetes mellitus and systemic stroid use.
Symptoms: When a patellar tendon tears there is often a tearing or popping sensation. Pain and swelling typically follow, and you may not be able to straighten your knee. Additional symptoms include indentation at the bottom of your kneecap (where the tendon tore) and difficulty walking due to knee buckling or giving way.
Severity of injury: Partial tears do not completely disrupt the soft tissue (similar to a rope stretched such that some fibers are frayed, but the rope is still in one piece). A complete tear will split the soft tissue into two pieces. When the patellar tendon is completely torn, the knee cannot be straightened actively. The patellar tendon often tears at the place where it attaches to the kneecap, and a piece of bone can break off along with the tendon. If the tear is caused by a medical condition (like tendinitis), it usually occurs in the middle of the tendon instead.
Treatment options: Very small, partial tears respond well to bracing-immobilization and physical therapy. Complete tears typically need a surgical repair that reattaches the torn tendon to the kneecap. Earlier done, the better! For severe tears with significant damage or those more than a month old, a hamstring tendon reconstruction graft to reconstitute the tendon may be necessary.
Expected result:Most athletes get back to about 85-90 % of their normal strength. The most common issues after surgery include weakness and loss of motion.
Return-to-activity timeline: Patellar tendon repairs can be fragile. Therefore, patients need to be on crutches for 6-8 weeks. A complete return to normal activities is usually anticipated between 5-8 months postoperatively.