Patellar tendonitis - Causes, symptoms, and treatment

Patellar tendonitis treatment can involve various options. In this article, we explain why we recommend the approach of relative rest and a graded strength training programme for treating patellar tendonitis to most of our patients. We also discuss what other treatment options could be used in addition to this, as well as the causes and symptoms of patellar tendonitis. Remember, if you need more help with an injury, you're welcome to consult one of our physios online via video call.

In this article:

1. What’s the difference between patellar tendonitis and tendinopathy?

2. What is patellar tendonitis?

3. What causes patellar tendonitis?

4. What happens to the tendon when you have patellar tendonitis?

5. Patellar tendonitis symptoms - what does it feel like?

6. Patellar tendonitis recovery time

7. Patellar tendonitis treatment

8. How we can help

I've also made a video about the causes and treatment of patellar tendonitis/tendinopathy:

What’s the difference between patellar tendonitis and tendinopathy?

For all practical purposes, it means the same thing. But in 2019, a bunch of the world leading experts on tendons decided that the best terminology for this sort of problem would be tendinopathy, rather than than tendonitis.

This is because '-itis' in the 'tendonitis' refers to inflammation, and researchers no longer think that inflammation is a key feature of this problem. In this article, we use the terms interchangeably.

What is patellar tendonitis?

Patellar tendonitis is an overuse injury that affects the patellar tendon. The patellar tendon is a thick tendon that runs over the front of your knee, from the lower edge of your kneecap (patella) to the front of the shin bone (tibia). It attaches your quadriceps muscles (front thigh muscles) to the shin bone.

Any activity that activates or uses the quadriceps muscles also loads the patellar tendon. Patellar tendonitis is most commonly found in people who do sports and activities that require a lot of fast, repetitive, high-force contractions of the quadriceps muscles, e.g. football/soccer, volleyball, tennis, long jump, fell running, and CrossFit.

What causes patellar tendonitis?

Overuse

Overuse injuries like patellar tendonitis develop when you either:

1. Do an activity that is a lot more intense or harder than what you’re used to, e.g. playing in a tournament that results in six hours of high-intensity play when you’re used to two hours;

2. Or you don’t allow your body enough recovery time between high-intensity training sessions. Whenever we train, our bodies (tendons included) sustain microdamage. If you allow enough recovery time, your body repairs this microdamage and as a result you grow stronger. But if you do another high intensity session before your body has fully repaired, the microdamage can accumulate and cause an overuse injury.

Trauma

The vast majority of cases of patellar tendonitis are caused by overuse, but sometimes a direct blow to the patellar tendon (e.g. someone kicks you or you bang your knee against something) can also cause the tendon to develop patellar tendonitis or tendinopathy.

What happens to the tendon when you have patellar tendonitis?

Healthy tendons are extremely strong structures. They are made up of mostly lots and lots of collagen fibres that are packed in parallel. They also have a few cells and some (not a lot) white, fluid-like substance between the fibres.

The collagen fibres in healthy tendons are packed close together, in parallel.

It’s the parallel structure of the collagen fibres that makes a tendon so strong. Remember that old experiment from school with the pieces of string? If you take one piece of string, it’s easy to snap. But as soon as you have ten pieces of string put together, it becomes impossible to snap them with your bare hands.

When you develop a tendonitis or tendinopathy, it only affects a small portion of the tendon. For the patellar tendon, it most often affects the area where the tendon attaches to the lower edge of the kneecap. When you look at that injured part under a microscope, you’ll notice:

• In newly injured tendons - That the collagen fibres have started to move away from each other, there’s more of the fluid-like substance between them, and the cells have also changed.
  

Microscopic image of a recently injured tendon (reactive tendonitis).

• If your patellar tendonitis has been dragging on for a month or two, you may notice that the collagen fibres in that area have totally lost their parallel structure, and there’s much more fluid-like substance. An ultrasound scan may also show new blood vessels growing into that area. Healthy tendons usually don’t have blood vessels growing into them.
  

Microscopic image of an ongoing tendonitis/tendinopathy. The injured potion of the tendon has lost its parallel structure.

Patellar tendonitis symptoms - what does it feel like?

Where you feel patellar tendonitis pain

The pain is felt over the front of the knee and most often in the area where the patellar tendon attaches to the lower edge of the kneecap. But it is possible to get it in other parts of the tendon.

Most commonly the pain from patellar tendonitis is felt at the lower edge of the kneecap.

Other conditions that can cause similar pain and are often mistaken for patellar tendonitis include quadriceps tendinopathy, infrapatellar bursitis, fat pad irritation, patellofemoral pain syndrome, meniscus tears, Osgood Schlatter’s (in children) and Sinding-Larsen-Johansson syndrome (in children).

When does it hurt?

It hurts whenever you do an activity that uses the quadriceps muscles (front thigh muscles). If your tendon is very irritated, even light activities like walking up and down stairs may hurt. If it’s not that irritated, then you may only feel pain when you do high-intensity activities like heavy squats, jumping, or running.

You may find that your knee actually feels pretty good when you start with your activity, but then the pain slowly starts to build as you continue. Or you may have some pain when you start training, but then it actually goes away as you warm up, only to return much more intensely later on. If you’ve neglected your patellar tendonitis for a while and continued to train through the pain, you may find that it’s too painful to do sport.

It is quite common to experience a delayed increase in pain, i.e. it is only 24 hours after doing an activity or training session that you suddenly experience an increase in pain. This is what makes tendon rehab so tricky - it usually doesn’t let you know at the moment when you’re overdoing things. That is why we teach our patients to monitor and interpret their 24-hour pain response rather than just focus on what they experience while they're doing their sport or activity.

Patellar tendonitis can sometimes cause pain when you sit with your knee bent for a long period. This is because the injured patellar tendon is under a bit of stretch and compression when your knee is bent, and that can cause it to become irritated if the position is sustained for too long. However, this is also a common occurrence when you have patellofemoral pain syndrome and why it’s best to consult a physio who can help you figure out your correct diagnosis.

Patellar tendonitis recovery time

Patellar tendonitis, like all tendon injuries, can take a very long time to heal. Most people will recover and return to full sport within six months. But researchers have found that up to a third of athletes will take longer than six months to recover and often more than a year. This is why it’s important to seek help early on to ensure that you’re applying the most appropriate treatment plan for your specific case.

Patellar tendonitis treatment

The successful treatment of patellar tendonitis usually involves a combination of different activities and treatment modalities. We've included the most widely used and best researched ones in the sections below.

1. Relative rest

Relative rest is different from complete rest in that you don’t have to stop all your activities. You can remain active as long as you reduce your activity intensity and volume to a level that doesn’t increase your pain.

The aim is to allow your tendon to settle down, so that you can progress with your rehab and build the strength you need to go back to full sport. By how much you have to adapt your training will depend on how irritated your tendon is.

For some athletes, this may mean that they have to stop all jumping and sprinting and just do low-load activities like walking or slow jogging. For others, it may mean that they just have to limit the volume, intensity, or frequency of their jumping and sprinting activities.

We always aim to keep our patients as active as possible, as that helps to maintain their current tendon strength. But this is not an exact science and requires careful monitoring to get it right.

Remember that relative rest should also take account of your normal day-to-day activities, and there are some everyday movements and positions that may aggravate your patellar tendon pain.

Current recommendation

You have to reduce the intensity of your activities to allow your tendon to calm down. Relative rest is superior to complete rest, as it not only allows the pain to settle but also retains more strength in the tendon.

2. Rehab for patellar tendonitis

Strength training exercises

There is very strong evidence that the best treatment for patellar tendonitis or tendinopathy is a structured strength training plan, consisting of exercises that specifically load the patellar tendon.

This should not come as a surprise because, as we discussed earlier, when you injure your tendon it changes structure and loses some of its strength. The only way to trigger the body to produce new tendon fibres and restore its strength to the level you need is strength training exercises.

What exercises you should do for patellar tendonitis is determined by your stage of healing, the sensitivity of your tendon, your sport, and your current strength.

Recent research has shown that there’s a wide variety of strength exercises and programmes that could work for treating patellar tendonitis - we discuss them in detail in this article. In our experience, not everyone reacts equally well to the same exercises. Every case of patellar tendonitis differs in severity and irritability and people also have different end goals. So it’s important that the exercise programme is tailored to the individual and adapted as your tendon heals.

Kinetic chain

When we move, our bodies function as a kinetic chain which means that if something happens in one area, it also affects areas that are further away. A lack of flexibility or strength in one area may for instance cause another area to overwork or overstrain.

Some areas in the kinetic chain that may affect your patellar tendon.

There is evidence that lack of hamstring and quadriceps flexibility, restricted ankle dorsiflexion range (how well your foot bends up towards your shin), as well as reduced calf and glute function may increase your risk of developing patellar tendonitis. This is why we do a comprehensive assessment of our patients and don’t just focus on their painful knees.

Biomechanics

Biomechanics refers to the movement patterns we use when we do different activities. For patellar tendonitis, the landing mechanics from a jump has been shown to be of importance.

Box jumps help to develop explosive strength and teach good landing mechanics.

This is perhaps not something that needs to be addressed during the early stages of rehabilitation, as your biomechanics may be different when you are still in pain and these exercises can easily irritate the tendon. But it is definitely something that should be assessed during the later stages, once you’ve built some strength and your pain has settled.

We’ll discuss the different exercise programmes and what an ideal exercise-based treatment plan for patellar tendinopathy should look like in a future blog post.

Current recommendation

Exercise remains the most effective treatment for patellar tendonitis, and several literature reviews have now confirmed this, but the exercise programme should be tailored to the individual needs of the patient and be adapted as their injury recovers. A one-size-fits-all approach is likely to aggravate the symptoms.

3. Shockwave

Shockwave can be a useful tool to help reduce pain. However, a recent meta-analysis of the current research found that adding shockwave to an exercise-based treatment programme for patellar tendonitis added no extra benefit.

Current recommendation

If pain is preventing you from doing any exercises or from making progress with your rehab, it may be useful to try shockwave, as it may reduce your pain sufficiently to allow you to progress with your rehab. However, if you’re already able to tolerate your rehab exercises, you're not likely to gain any extra benefit from adding shockwave to your treatment regime.

4. Massage

Massage may be useful to help reduce pain in the short term, but it doesn’t actually strengthen the tendon. Exercise has been shown to provide better short and long term results for pain reduction than cross-friction massage specifically.

Current recommendation

Don’t rely on massage alone for your recovery. You have to also follow a structured exercise-based rehab programme.

5. Anti-inflammatory medication

Anti-inflammatory medications (NSAIDs) like ibuprofen or Naproxen are sometimes prescribed to help decrease your pain when you have patellar tendonitis. However, the research has shown that inflammation isn’t actually what causes the pain in ongoing tendonitis or tendinopathy.

More importantly, research has also shown that anti-inflammatory medication may slow down the rate at which your body creates new collagen fibres in response to exercise. The whole point of doing the strength training exercises is to stimulate your body to produce new collagen fibres and to strengthen your injured tendon!

Current recommendation

Don’t use anti-inflammatory medication to treat patellar tendonitis. Discuss other options for pain management with your doctor. Paracetamol might be a better choice.

Anti-inflammatory medication may reduce the benefits your patellar tendon is meant to gain from doing rehab exercises.

6. Topical glyceryl trinitrate

There is some evidence that using topical (applied to the skin) glyceryl trinitrate in combination with an exercise plan may work better for reducing pain than exercise on it’s own. However, it does come with some side effects that may include skin irritation and headaches.

Current recommendation

Topical glyceryl trinitrate may be an useful adjunct to treatment if you’ve not seen any progress with your exercise programme after 12 weeks.

7. Platelet rich plasma (PRP) injections

There is some evidence that PRP injections may be useful as part of the treatment for patellar tendonitis, but only when it is combined with an exercise plan. We are not yet sure what technique is superior or how many injections work best. They also don’t work for everyone.

Current recommendation

PRP injections on their own are not useful. They have to be combined with a graded strength training plan. It’s a treatment to consider if you’ve failed to make significant progress after 12 weeks of following a tailored exercise programme.

PRP injections may be useful for treating patellar tendonitis, but corticosteroid injections should be avoided.

8. Steroid injections

In the past, a steroid (corticosteroid or cortisone) injection was a standard treatment for any tendon injury, because it is pretty good at reducing the pain. However, now that a lot more research has been done, it has become clear that it might not be a good idea to inject a tendon with cortisone.

Cortisone has been shown to slow healing and may predispose you to a tendon rupture. Steph discusses the use of steroid injections in more detail in this video.

Current recommendation

Do not use cortisone or steroid injections to treat patellar tendonitis/tendinopathy.

9. Patellar tendonitis strap or taping

Some people find that using a patellar strap that applies pressure over the patellar tendon can reduce their pain while playing sport. Others find that tape can also provide some relief. There currently isn't much high-quality research available to back this up. A recent randomized controlled trial did show that both patellar tendon straps and tape can help to reduce pain, but they failed to show a significant difference between using a patellar tendon strap, applying a specific taping technique, and placebo tape (tape just stuck on in any way).

Current recommendation

A patellar strap may reduce your pain while playing sport, but this would likely be due to a placebo effect. Don't use this as a standalone treatment for patellar tendonitis. Make sure that you combine it with a comprehensive rehab plan.

Patellar straps and tape may reduce your pain.

10. Surgery

Surgery should only be considered if you’ve followed a structured and progressive strength training programme for at least 12 months and not seen any progress. About 10% of patients with patellar tendinopathy seem to undergo surgery. There is currently no consensus on what type of surgery is best.

Current recommendation

Only consider surgery if you’ve failed to get results from a well-designed (tailored to you) exercise-based treatment plan for at least 12 months.

How we can help

Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.

We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Sports Injury Physio we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.

About the Author

Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.

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