A quadriceps tendon rupture is a rare but serious knee injury.
Quads tendon tears are caused by sudden overloading of the quads tendon, which connects the quadriceps muscles to the kneecap.
There may be a partial or full thickness tear of the quads tendon, which can affect knee extension and activities such as walking and climbing stairs.
With a complete quadriceps tendon rupture, surgery is advised within the first 4 days to prevent further complications.
Here we look at the common causes, symptoms, diagnosis and treatment options for partial quads tears and complete quadriceps tendon ruptures.
The four quadriceps muscles, rectus femoris, vastus medialis, vastus intermedius and vastus lateralis, run down the front of the thigh and join together to form the quadriceps tendon.
The quads tendon is a thick, tough band of fibrous connective tissue that surrounds the kneecap and attaches the quads muscles to the patella.
Below this, the patellar tendon connects the patella to the front of the tibia, shin bone.
The quads muscles, quadriceps tendon, patella and patellar tendon make up what is known as the “extensor mechanism” of the knee.
When the quads contract, they pull on the quadriceps tendon, which in turn pulls on the kneecap and patellar tendon. This allows us to extend, or straighten, the knee and perform actions such as kicking.
Tendons are strong structures but they are not particularly flexible so if they are suddenly overstretch or overloaded, they can tear.
There are two types of quadriceps tendon tears:
Partial Quadriceps Tear: When some of the fibres are torn but the tendon remains intact – think of it like a fraying rope
Ruptured Quadriceps Tendon: when the tendon tears completely so it is no longer anchored to the patella
If the quadriceps tendon ruptures, it disrupts the extensor mechanism making it impossible for the knee to straighten independently.
A quadriceps tendon rupture is a rare knee injury typically caused by:
Quadriceps tendon ruptures most commonly affect:
Typical symptoms of a torn quadriceps tendon are:
Doctors can often diagnose quadriceps tendon tears from your history and a physical examination. They will ask questions about how your injury occurred and what symptoms you are experiencing. They will also want to know if you had any symptoms prior to the injury to evaluate the likelihood of an underlying quads tendinopathy.
They will then look at the strength and movement in your leg including whether you can straighten your knee against resistance, perform a straight leg raise (SLR) without the knee sagging/bending and perform a squat.
They will also palpate the knee and surrounding area to see if they can feel a gap in the tendon.
You doctor may send you for x-rays, ultrasound or an MRI scan if there is any uncertainty about the injury, or to confirm whether there is a partial or full quadriceps tendon rupture.
Non-surgical treatment is indicated if there is a partial quad tendon tear, or for patients who would not tolerate surgery. Treatment typically involves:
People usually make a good recovery from a small, partial quads tear without needing surgery and your doctor or physical therapist will be able to advise you on when you can return to sports/activities.
With a complete quadriceps tendon rupture, knee surgery is almost always necessary, particularly when there is loss of the extensor mechanism. Surgery may also be advised for large partial quads tendon tears, or if there is underlying degeneration from quadriceps tendinosis.
The most common surgical technique is to drill holes into the kneecap. Sutures, aka stitches, are placed through the tendon and then looped through the drill holes.
The surgeon pulls the sutures to the correct tension to reattach the quads tendon to the patella and ensure that the kneecap is in the correct position.
More recently, a new type of surgery has become popular where rather than drilling holes into the kneecap, suture anchors (small metal implants) are used instead.
There is so far insufficient research to say which method works best, but it is thought that using suture anchors decreases gap formation and increases tendon strength.
The sooner knee surgery is carried out following a ruptured quads tendon, the better the outcome. This is because the damaged tendon will quickly tighten and develop scar tissue leading to shortening of the tendon.
Ideally, surgery should be performed within 48-72 hours of the quadriceps tendon rupture. Ruptures more than 2 weeks old can retract by around 5cm, making surgery more challenging, and potentially limiting functional recovery.
If knee surgery has been delayed and the quads tendon has significantly shortened, then a graft is inserted to bridge the gap and lengthen the tendon.
Following surgery for a quadriceps tendon rupture, the knee is normally immobilized in full knee extension using a brace or knee immobiliser splint and crutches for 4-6 weeks. This allows the tendon to heal in the correct position and reduces the risk of re-injury. The surgeon may also limit how much weight you can put through your leg initially.
Physical Therapy will be necessary to work on the correct blend of progressive strengthening and flexibility exercises. Initially, you will concentrate on isometric strengthening exercise to strengthen the knee without moving it.
As things progress, your doctor or physical therapist will start to unlock your knee brace to allow a small, controlled amount of movement in the knee when weight-bearing without overstressing the quads tendon. After around 4-6 weeks, you should be able to stop wearing the brace altogether and can instead focus on knee exercises to regain mobility and flexibility.
Some surgeons advocate the use of early joint mobilization in an attempt to reduce knee stiffness and muscle wasting. There is conflicting evidence over which method is best but there is definite agreement that the sooner surgery is carried out for a quadriceps tendon rupture, the better the recovery.
It usually takes around 4-6 months to recover from surgery for a quadriceps tendon rupture, and in some cases it can take up to one year to return to your usual activities.
Before returning to sports or strenuous activities you should:
If you has a partial quads tear rather than a complete rupture, it usually takes 6-12 weeks to regain full function.
The most common complications following a quads tendon rupture are:
Outcomes have been shown to be more favourable with early surgical intervention after a torn quads tendon with most people returning to full function with a year.
Page Last Updated: September 9, 2020
Next Review Due: September 9, 2022