Quadriceps tendinitis, also known as quadriceps tendinopathy or tendinosis, is an overload, tearing, and inflammation of the tendon at the top of your knee cap. This tendon links the quadriceps muscles to your knee cap to straighten your knee. Your quadriceps tendon pain can be in one of 3 stages of tendon damage. Each stage is an escalation of the continuing destruction of the loadbearing capacity of the tendon. If you’re feeling tendon pain over the front of your knee or lower thigh you need an expert eye to have a look at it before it gets worse.

Onset of your quadriceps tendon pain can be sudden or it can develop gradually over time. The cause of quadriceps tendinitis is a repetitive movement like climbing up and down many flights of stairs or doing a lot of squats or lunges. Repetition under large amounts of force combined with speed and power creates the ideal circumstances for quadriceps tendinitis to develop.

The muscle on the front of your thigh is called the quadriceps femoris and is a group of four muscles: Rectus Femoris, Vastus Lateralis, Vastus Medialis, and Vastus Intermedius. Just above your knee, the bottom part of these muscles form the quadriceps tendon which attaches to the top of the patella (knee cap).

A tendon is made up of parallel collagen fibers that connect muscle to bone. Collagen is a strong type of connective tissue that can withstand a lot of tension. Tendons need less energy and oxygen to function, so they can withstand load and tension for longer periods than muscles.

Tension in the quadriceps tendon keeps you from falling when going downstairs and allows you to sit down slowly instead of just dropping into a chair. The tendon maintains this tension to hold or control the movement of your knee. This means that bending or straightening your knee isn’t just all or nothing – you can bend your knee slightly and hold that position.

The quadriceps tendon acts like a pulley connecting the muscles on the front of your thigh to your kneecap. When the muscles contract it creates tension in the quadriceps tendon which causes the knee to straighten. This happens every time you walk up a step or get up from a chair.

In everyday activities like standing the quadriceps tendon keeps our knee straight and straightens the knee with every step we take. During downhill running the tendon controls the amount that the knee bends to keep you from stumbling. Tendons absorb kinetic energy to transfer it into the muscle or Tibia.

The quadriceps tendon handles significant loads during sporting activities. For example, to jump into the air a large amount of force is transferred through the quadriceps tendon to get you off the ground. When landing the quadriceps tendon works hard to keep your knee from bending all the way, so it also acts like a shock absorber to soften the landing.

Healthy tendons are made up of densely packed, parallel collagen (connective tissue) fibers. This specific structure of tendons is what makes them so strong and resilient. The blood vessels that supply tendons also run parallel to these fibers, but the inner part of the tendon has a relatively poor blood supply.

Reactive tendinopathy

With overuse or overloading, there will be thickening of the tendon to reduce stress on the tendon. There isn’t any inflammation during this phase and, if the load is reduced in time, there isn’t any permanent damage to the tendon. However, the thickening can cause some loss of flexibility. This process is called reactive tendinopathy. A normal tendon responds to load and tension by stiffening, so the thickening is your body’s way of compensating for a lack of stiffness, trying to heal the tendon. Therefore your tendon works like a worn-out spring that struggles to recoil & expand.

This is usually caused by a sudden increase in activity, for example, someone who doesn’t normally run doing a trail run.

Tendon disrepair

If reactive tendinopathy is not managed properly – by decreasing the load on the tendon – your body will carry on this “healing” process. Unfortunately, this phase is different, because there is an increase in destructive cells in the tendon (not just collagen). These cells cause separation and disorganization of the normal collagen in the tendon and small blood vessels develop in the inner part of the tendon, disrupting the tendon’s fibers from absorbing load. This is when the quadriceps tendinitis becomes painful.

We normally see this when people carry on training through the pain for weeks or months. The tendon doesn’t have time to adapt in between the activities that cause the quadriceps tendinitis, like downhill running.

Trauma

Repeated tissue trauma to the front of your kneecap, like kneeling on your knee, triggers the same destructive mechanisms that set off a tendinitis to evolve.

Degenerative tendinopathy

This phase is normally seen in older patients or athletes who keep on overloading the tendon for months or years. If you reach this phase, your condition cannot be reversed, because there are areas of “dead” tendon that cannot heal. These areas have lots of small blood vessels and very little collagen.

It’s not all bad news though, because there are areas of the quadriceps tendon that can still heal and this is what we as physiotherapists will focus on during treatment.

Quadriceps tendon pain develops quickly or you could gradually develop pain over a while.

Sudden onset

A single incident, like after a sudden acceleration (a sprinter’s push-off out of the blocks), jumping off a wall, or falling directly on your knee causes small tears in the tendon. This leads to quadriceps tendinitis because the tendon is loaded beyond its normal limits. Like a cable that snaps.

When you exercise – especially in activities like downhill running, box jumps, and kicking – the tendon must absorb the forces placed on it. However, tendons do not respond well to changes in activity. If you make big changes to your training, the load on the quadriceps tendon will be higher than it’s used to. This causes inflammation and swelling of the quadriceps tendon which you will experience as pain at the front of your knee.

Gradual onset

The main cause of quadriceps tendinitis is overuse and repetitive overload. Tendons need time to recover after training, so insufficient recovery (“healing”) time causes quadriceps tendinitis. This is why it’s important not to go back to training before your pain has settled. A tendon takes up to 48 hours to respond to load.

People who lead sedentary lives (if you sit for 6 hours a day, behind a desk or in traffic) have an increased risk of developing quadriceps tendinitis. The knee is in one position throughout the day, leading to tightness of the quadriceps muscles. When you do other activities, like climbing stairs or getting into your car, you need the full range of movement of the knee, but the tightness adds extra tension and load to the quadriceps tendon. Think of a big industrial cable under tension that cannot stand the loads placed on it – over time it starts to fray.

Running downhill your quadriceps muscle controls the deceleration of your body, working as your “brakes”. Repetitive downhill running puts excessive force on the patella tendon and this is also referred to as runner’s knee.

Symptoms are the words your patient will use – in a subjective assessment.

Try to resonate the exact words used by your patients to describe it to you. Then Read your symptoms again and imagine a patient reading it to you… (Does it fit into the Title Diagnosis) can you describe it even better (signs they haven’t even noticed yet)

Self- test your … at home with these modified tests and see if you might have a ….

Use your key phrases abundantly here, if you need a few more.

Load progression in your tests.
Do not use “try to..” – keep to clear instructions. It’s an ‘must do’ instruction.

Try to describe at least:

• Weight bearing
• Loaded
• Unloaded
• Stretch/ End of Range

In the early stage of quadriceps tendinitis, you will have pain above or below the patella after training or activity.  The pain goes away with rest but returns after your next training session. This phase is known as reactive tendinopathy. If the tendon is overloaded there will be some thickening of the tendon to reduce stress on the quadriceps tendon. Normally tendons respond to loading by an increase their stiffness.

Without treatment, you will find that you have pain at the beginning of your training, but it disappears after your warm-up.  The pain returns after training and settles again with rest. Taking longer and longer to ‘recover’. This stage is known as tendon disrepair.  Your body tries to heal the small tears in the tendon when you rest, but you resume training before the tendon heals completely resulting in degeneration of the tendon.

If you do not get treatment in the previous stages of quadriceps tendinitis and continue overloading the tendon, your condition progresses to degenerative tendinopathy.  There will be areas of cell death in this phase which can not heal. During this phase, you will have pain and stiffness during and after activity.  The pain does not settle with rest and you will hesitate even to exercise at all.

The quadriceps tendon is very thick and combines the forces of the four quadriceps muscles – like four motors attached to one cable. If the force of the motors (muscles) is unevenly distributed to the cable, the cable starts shearing away from the motor. There are four points where the tendon tears.

• Above the knee cap, where the muscle attaches to the tendon, about two fingers above the knee cap (patella).
• Where the supra-patella tendon attaches to the top part of the patella (superior border).
• Below the patella (inferior border).
• At the attachment of the infra-patella tendon onto the tibia (shin bone), about four fingers below the knee cap.

A Physiotherapist can diagnose quadriceps tendinitis by doing specific tests to load the tendon.  We assess the quadriceps muscle strength and tightness to find all the factors contributing to your pain. During our evaluation, we also do passive joint tests and put pressure on other parts of the knee to pinpoint the exact problem. We screen your whole leg to identify weakness, tightness, or stiffness at your hip and ankle/foot which may contribute to your condition.

If we suspect damage to some of the other structures in the front of your knee we can refer you for further investigations. For example, if we suspect the tendinitis has deteriorated to such an extent that there may be ligament damage or quadriceps muscle tears. In our experience, these are the patients who disregard the pain and just run through it for weeks or even months.

X-rays only show bone, not tendons and ligaments. It may be used to rule out avulsion fractures where a piece of bone breaks away with a tendon rupture. With a normal quadriceps tendinitis a X-ray will be of little value.

Diagnostic ultrasound shows the soft tissue and will be more useful than X-rays for quadriceps tendinitis. Any swelling, tendon thickening, involvement of the bursa or possible tears in the tendons will be visible.

MRI can only be ordered by a surgeon. If your knee injury was traumatic (accident, tackle, or landing awkwardly) an MRI visualizes the structures within your knee joint to rule out any other injuries to the menisci (Knee Meniscus Tear) and ligaments (Anterior Cruciate Ligament injury (ACL injury).

When the tendon is overloaded with forces from the pull of the quadriceps muscles, inflammation causes your body to send cells to repair the micro tears in the tendon fibers. Almost like a cable that starts to fray, snapping small strands one at a time. If you keep on running through it, you will continue to tear away the cells that are trying to heal and close the tears. The more you run, jump, squat, or lunge through the pain, the more damage you cause and the longer it will take to heal.

Your pain and tightness will be worse AFTER the activity rather than during. The reason for this is the inflammatory cells attempting to heal the tissue when you rest, causing an increase in pressure in and around the tendon. Tendons have poor blood supply compared to muscles and, therefore, take longer to heal and recover.

A big problem that we see with quadriceps tendinitis is that patients delay treatment. In the early phases of the quadriceps tendinitis/tendinopathy, the pain settles down with rest, but the tendon degeneration and muscle tightness do not go away with rest. If you take a few days off until the pain in your knee is gone (usually 5 days) and then start running again, the pain will return. The cells that have started to heal will tear and the whole process needs to start from the beginning again. 

Too late

By the time patients make an appointment to see a physiotherapist, they have had to stop training due to their quadriceps tendon pain. This means that their tendinitis has progressed to the stage of tendinopathy where there is degeneration of the tendon. As soon as there is degeneration we need to drastically change your activity to limit further damage to the tendon. This means that you will have to take time off from whatever is causing your pain. If you make an appointment with us before you reach this stage, it might only be necessary to decrease the load of your activity without stopping completely.

No time to accommodate

Another problem we see is that patients do not want to rest or change their activity. Tendinitis is an overuse injury, so the tendon needs active rest to heal, so you must modify your activity. If you carry on with your normal activities and training – which caused the problem in the first place – the tendon will not heal and the condition will just get worse until you’re forced to stop.

The most important part of physiotherapy treatment for quadriceps tendinitis is modifying your activities and training.  The first thing to do with an overuse injury is to change what is causing the problem in other words manage the load on the tendon.

When you still have a lot of pain we will see you twice a week for treatment. This treatment will focus on pain management through electrotherapy, strapping, and isometric exercises. Muscle tightness and trigger points will be addressed by acupuncture or dry needling, massage, and stretches. Ultrasound, laser, strapping, and taping will be used during the course of treatment to support the healing process.

As soon as your pain is under control we start to load the tendon with exercises specific to the phase of healing you are in. We will gradually progress your rehabilitation exercises to increase the tendon’s ability to handle these loads. Tendons take longer to heal than muscles, so rehabilitation can take 3 to 6 months.

1. You will start with open-chain exercises, in other words, exercises where you don’t put weight on your foot. These exercises put very little strain on the tendon and are different variations of knee extension (straightening). Starting with exercises where there is very little to no movement (isometrics) and gradually increasing the range of movement of the exercise.
2. Next, you will start with partial weight-bearing exercises like wall squats progressing to normal squats. The other leg takes some of the weight during these exercises, so all of the load isn’t on your injured knee.
3. After partial weight-bearing, we start conditioning your tendon to tolerate full weight-bearing like lunges progressing to single leg squats and pistol squats. These exercises are only performed with body weight until your tendon can do these movements without pain.
4. Now you’ll progress to loaded exercises like knee extensions against elastic resistance and weighted squats. Initially with easy resistance, but before we move on from loaded exercises you will do heavy, slow resistance exercises. This is important to change the tendon’s capacity to withstand loading which leads to long-term improvement in your quadriceps tendon pain.
5. The next part of rehabilitation involves the stretch-shortening cycle of the tendon. This is when the tendon acts like a spring for jumping activities, going from a lengthened position (stretch) to a shortened position (contraction) in a short time. A tendon should be able to withstand this kind of load without flare-ups or pain. Exercises will include skipping, box jumps and single leg hops.
6. Running drills will be some of the last exercises before you finish rehabilitation. These drills will include acceleration and deceleration, rapid direction changes, and a combination of running and jumping.

Your Quadriceps tendon has a poor blood supply compared to muscles, hence their white appearance on anatomy charts. Depending on the stage of your tendinitis, healing time could be from 6 weeks to 3 months. Initially, physiotherapy treatments will be once to twice a week (depending on your pain), but as your quadriceps tendon pain improves we will see you once a week and later once every second week to progress your rehabilitation progressive loading program.

• Medication – Your GP may prescribe analgesics or anti-inflammatories to decrease pain.
• Cortisone injections – A cortisone injection will clear all inflammation in the area, which decreases your quadriceps tendon pain considerably. However, it causes changes in the integrity of the tendon which can lead to tears or ruptures in the future.
• Brace – A knee ranger can be used to limit movement while your quadriceps tendon heals.

If your quadriceps tendon pain does not respond to 3 months of non-surgical treatment, surgery may be an option. Another reason for surgery would be if there is a complete rupture of the tendon off its anchor sites.

Surgery is performed via arthroscopy (keyhole surgery) to remove the damaged tissue and/or repair the quadriceps tendon. After surgery, rehabilitation is crucial to restore the tendon’s normal function and to strengthen all the muscles around your knee. Without rehabilitation, there is a very high risk of re-injury to the quadriceps tendon.

• Patella dislocation – The pain is more on the outer side of the patella. Swelling is the main difference. A quadriceps tendinitis rarely swells.
• Patellar bursitis – Pain is worse during activity and specifically when kneeling on the ground. Pressure on the area makes your pain worse.
• Quadriceps muscle strain (tear) – Your pain is over the front of your thigh rather than your knee.
• Knee Joint Osteoarthritis – The pain is deeper and you have more knee stiffness in the mornings or after sitting still for a while.

• Quadriceps tendonitis
• Runner’s knee
• Quadriceps tendinopathy
• Pain over the knee cap
• Quadriceps tendonosis