Patellar tendon rupture: symptoms, surgery and recovery

Tendons are strong cords of fibrous tissue that attach muscle to bone. The patellar tendon runs from the bottom of the kneecap to the top of the shinbone. The AAOS explains that the quadriceps muscles, the quadriceps tendon and the patellar tendon work together to enable you to straighten the knee. Because a structure that joins bone to bone is technically a ligament, the patellar tendon is sometimes called the patellar ligament.

Tears can be partial or complete. In a partial tear some fibres are frayed but the tendon is still in one piece. In a complete tear the tendon is separated from the kneecap and, without this attachment, you cannot straighten your knee. It often tears at the point where it attaches to the kneecap, and a piece of bone can break off with it.

This guide uses a UK physiotherapy provider’s information and the American Academy of Orthopaedic Surgeons because no NHS patient page on this specific injury was found when this guide was prepared. Rehabilitation schedules differ between UK surgeons and hospitals, so treat the timings as examples and follow your own team’s plan.

The AAOS says it takes a very strong force to tear a healthy patellar tendon. Common causes include a fall or direct blow to the front of the knee, deep lacerations, and landing awkwardly from a jump with the knee bent and foot planted. Physio.co.uk similarly says both partial tears and ruptures can occur when a violent force is exerted by the contracting quadriceps, for example when landing from a jump.

A weakened tendon is more likely to tear. The AAOS lists patellar tendinitis, corticosteroid injections around the tendon, oral corticosteroid or anabolic steroid use, chronic disease that disrupts blood supply (such as chronic kidney failure, inflammatory diseases and diabetes), infection, and previous surgery around the tendon such as total knee replacement or anterior cruciate ligament reconstruction.

When a patellar tendon tears you often experience a tearing or popping sensation, according to the AAOS. Pain and swelling typically follow and you may not be able to straighten your knee. The AAOS lists the additional signs below.

• An indentation at the bottom of the kneecap where the tendon tore.

• Bruising and tenderness, and sometimes cramping.

• The kneecap moving up into the thigh because it is no longer anchored to the shinbone.

• Difficulty walking because the knee buckles or gives way.

A suspected complete rupture, particularly if you cannot straighten the knee or lift the leg, needs prompt assessment by an urgent care service or A&E, because surgery is best done soon after the injury. Physio.co.uk says surgical repair should be done as soon as possible after the injury, though it can in some cases be delayed for up to a week to allow swelling to reduce, during which the knee is immobilised.

If you are unable to put any weight on the leg, cannot straighten the knee or have severe pain and swelling after an injury, you can contact NHS 111 or go to an urgent treatment centre or A&E. Call 999 if there is serious injury, severe bleeding or other life-threatening symptoms. This is general injury advice rather than guidance specific to the sources used here.

The AAOS says doctors discuss your history and symptoms and examine the knee, testing how well you can extend or straighten it. This part of the examination can be painful, but it helps determine whether you have a patellar tendon tear or a different injury. To confirm the diagnosis, they may order imaging.

On an X-ray the kneecap moves out of place when the patellar tendon tears, which is often very obvious on a side view, and complete tears can often be identified with X-rays alone. An MRI scan shows soft tissues, such as the tendon, and can show the amount of tendon torn and the location of the tear, or rule out other injuries with similar symptoms.

The AAOS says treatment depends on the type and size of the tear, your activity level and your age. Very small partial tears respond well to non-surgical treatment, while complete tears are almost always treated with surgery.

The AAOS says that after surgery the repair is most likely protected with a knee immobiliser or, rarely, a long leg cast, with crutches or a walker and the leg in a straight position. Skin sutures or staples are removed about 2 weeks after surgery. By 2 to 4 weeks the leg can usually bear about half of body weight and after 4 to 6 weeks it should be able to handle full body weight, though it depends on the tear, the repair and the surgeon’s recommendations.

Over time the brace is unlocked to allow more movement and strengthening exercises are added. Physio.co.uk says that after repair you will experience pain, stiffness, swelling and limited range of movement, that the knee is immobilised in a brace with elbow crutches so you can partially weight bear as tolerated, and that you will be unable to drive for up to 6 weeks. The AAOS lists weakness, loss of motion, re-tears, the repaired tendon detaching from the kneecap and a different kneecap position among possible complications, alongside the usual risks of infection, wound breakdown, blood clots and anaesthetic complications.

A complete rupture is normally managed by an NHS orthopaedic or trauma team, because early surgery is recommended. Rehabilitation is usually through NHS physiotherapy, which can involve waits.

Some people use private orthopaedic surgeons or physiotherapists, mainly for quicker access to rehabilitation or follow-up. The surgery itself is broadly the same, and the plan, brace settings and exercise progression should come from your surgeon. Ask who will oversee your rehabilitation, what the weight-bearing and brace schedule is, and what signs of problems to look out for.