Overview

What is patellar tendonitis, and what else may it be known as?

Patellar tendonitis, also referred to as patellar tendinopathy, or ‘jumper’s knee’, is a common occurrence in athletes who participate in jumping sports, for example, volleyball and basketball.¹

It is to be noted that patellar tendonitis does not only occur in athletes who participate in jumping sports.

Patellar tendonitis is a common soft tissue injury, which is characterised by pain felt in the front (anterior) of your knee.¹ This pain is due to there being repeated stress on your patellar tendon.

What is the patellar tendon?

The patellar tendon joins the quadriceps (muscles in your thighs) to your shin bone via the knee cap (patellar bone). Without the patellar tendon, you would be unable to straighten your knee and would be unable to participate in everyday activities such as running and walking.

What happens to the patellar tendon in patellar tendonitis?

Patellar tendonitis occurs when the patellar tendon has repeated stress applied to it and is overused. This results in too much pressure being applied to the patellar tendon, which results in small tears in the patellar tendon, known as micro injuries. These micro injuries change the structure of the patellar tendon.

How common is patellar tendonitis?

Patellar tendonitis is an injury that can affect anyone, however, it is more prevalent in the following groups of individuals:

• Those aged 15-30
• Those who take part in jumping sports, and sports involving running and hopping, such as tennis, basketball, football, and volleyball
• Older sporting individuals

Causes of patellar tendonitis

Overuse and repetitive stress

Activities involving frequent jumping and running

Repeated stress on your patellar tendon can result in patellar tendonitis. This has been demonstrated to be a common cause of patellar tendonitis in recreational and professional athletes, occurring typically in those who participate in the following:

• Football
• Volleyball
• Long-distance running
• Ice-hockey
• Basketball

Strain from sports

Strain from sports is a cause of patellar tendonitis in athletes. One study, looking at volleyball and basketball players, found that there was a greater risk of developing patellar tendonitis in athletes who played at a higher level (national compared to regional level). This is because playing at a higher level results in a heavier load being placed on the kneecap more often due to the athletes having stronger, more powerful muscles and being able to jump higher as a result.²

Heavier load in jumping sports

Studies have found that having a heavier load in jumping sports is a risk factor for patellar tendonitis.²

Physical factors

Muscle imbalances

If you have an imbalance of strength in the muscles in your legs, including the quadriceps and hamstrings. The stronger muscles can pull harder on your patellar tendon. This uneven pull can result in patellar tendonitis.³

Tight leg muscles

Having tight quadriceps and hamstrings can result in more strain being exerted on your patellar tendon, resulting in patellar tendonitis.

Structural issues

If you have one of the following, you have a higher risk of developing patellar tendonitis:

• Knock knees
• Flat feet
• Wide hip

This is because more stress will be exerted on your patellar tendon whilst you are exercising.

Gender

It has been reported that those assigned male at birth are more likely to develop patellar tendonitis than those assigned female at birth. One survey reported that the occurrence of patellar tendonitis was significantly higher in individuals assigned male at birth than in individuals assigned female at birth. The survey reported that 25.3% of those assigned male at birth had patellar tendonitis, whilst only 13.1% of those assigned female at birth had patellar tendonitis. You may ask why gender is a risk factor for patellar tendonitis. Well, one explanation for this is that for those assigned female at birth, their patellar tendon is exposed to lower forces, due to them having less quadriceps strength than those assigned male at birth.²

Weight

Being overweight is a risk factor for patellar tendonitis.

Strength in your stomach muscles

If you have poor strength in your stomach muscles around your pelvis, waist and lower limbs, force generation down your lower limb can result in an overload in the stress applied to your patellar tendon. Unfortunately, this can result in patellar tendonitis.

Sudden increase in activity

Abrupt changes in training intensity or frequency

If you start to overuse your patellar tendon and place additional stress on the tendon, due to you starting to train more, and at a higher intensity, the overloading of stress on the patellar tendon can sadly result in patellar tendonitis.

Training errors

You may make some training errors, if you are an athlete, which may result in patellar tendonitis. These errors include the following:

• You increase the intensity too soon, such as increasing running distances too soon
• You are doing too much weight training, for example, weighted squats
• You are doing too many plyometric exercises (exercises involving jumping)
• You are doing too much hill running
• Your training regime is not varied enough

Equipment and playing surface

Inadequate footwear

If your footwear lacks the proper cushioning either due to age or being poor quality, when you are participating in sports and activities, impact forces in your lower limb, from jumping for example, can result in more force being exerted on your patellar tendon. This results in patellar tendonitis.

Playing surface

For athletes, the type of playing surface is a risk factor for patellar tendonitis. One study found that 38% of those who played on concrete had patellar tendonitis, whereas athletes who played on other surfaces had a lower prevalence of patellar tendonitis, at 20%.²

Symptoms of patellar tendonitis

Pain

Pain is typically the first symptom of patellar tendonitis.

Where is the pain located, and does it go away?

The pain from patellar tendonitis is localised at the front of the knee, where the patellar tendon is. In the early stages of this condition, many experience pain at the beginning of exercise; however, this pain begins to disappear as the exercise continues. As this condition progresses to a more advanced stage, the pain in the front of your knee may be there throughout exercise, which may result in you finishing the activity prematurely. Patients with patellar tendonitis also report pain during sitting for a prolonged period of time, and when ascending and descending flights of stairs.⁴

You may experience pain when you are participating in physical activities, such as walking, running and jumping.

What is the nature of the pain?

The pain experienced is a dull aching pain at the front of the knee, rather than a sharp aching pain.

Swelling and tenderness

Where is the swelling and tenderness located?

If you have patellar tendonitis, you may experience mild swelling around the knee joint, in addition to tenderness located at the front of the knee. Whilst the tenderness is present throughout the patellar tendon, you may experience this more at the inferior pole of the tendon, where it is attached to your tibia bone via the tibial tubercle.⁴

Is the knee sensitive to touch?

When you touch your knee it may be sensitive to touch; this sensitivity is more prevalent when you extend your knee and touch your knee joint.

Stiffness

When is stiffness experienced?

Typically, stiffness is experienced in the knee joint in the morning. However, this stiffness eases after a few minutes of walking. This stiffness may be experienced at other points during the day too. For example, stiffness in the tendon may be experienced after exercise.

Weakness

Where is the weakness experienced?

Weakness may be felt around your knee joint and/or the thigh muscles -your quadriceps.

Summary

• Patellar tendonitis is a soft tissue injury which occurs when your patellar tendon (in your knee) is overloaded and put under too much stress, resulting in micro tears and injuries in the tendon
• Patellar tendonitis is also referred to as ‘Jumper’s Knee’ due to the high occurrence of this condition in athletes who participate in jumping sports, such as volleyball and basketball
• Patellar tendonitis has several risk factors and causes, especially if you are an athlete in sports such as basketball and volleyball, where inadequate footwear, training errors and training too intensely can result in patellar tendonitis
• Patellar tendonitis may be caused by being overweight, having tight quadriceps and hamstrings, having a muscle imbalance and other physical factors
• Patellar tendonitis has a range of symptoms, including pain in the front of the knee, which is the first symptom to be experienced
• Other symptoms of patellar tendonitis include weakness in the knees, stiffness in the morning when you wake up, tenderness around the tendon, and swelling around the knee joint