Overview

Patellar tendonitis, also known as jumper’s knee, runner’s knee or patellofemoral pain syndrome (PFPS) refers to the inflammation of the patellar tendon. The patellar tendon is a connective tissue which connects the patella (commonly known as the kneecap) to the tibia (or the shin bone). Patellar tendonitis is most commonly seen in athletes who practice sports involving jumping and hard surfaces, such as basketball, volleyball and badminton. 

Patellar tendinopathies (including patellar tendonitis, patellar tendinosis, and patellar tendon rupture) are relatively uncommon among the general population, having a prevalence of only 0.1%compared to 18.3% in sportspersons who use the tendon for repeated energy storage and release during physical activity.¹ For the people it does affect, patellar tendonitis can make daily activities such as walking difficult, and affect an individual’s physical as well as mental well-being.

So, how to identify patellar tendonitis? What are its causes? How can it be managed at home? And when to consult a clinician? These are some of the questions this article aims to answer.

Biomechanics of the knee

The knee is a complex and dynamic joint primarily involved in lower leg movement, posture and stabilisation, shock absorption, and supporting the body when standing or moving. It comprises ligaments, tendons, cartilages and three bones – the femur (thigh bone), the tibia (shin bone), and the patella (kneecap). 

Ligaments are bands of tissue which connect bone to bone. There are of two main types of ligaments in the knee joint: collateral ligaments (the medial and lateral collateral ligaments) and cruciate ligaments (the anterior and posterior cruciate ligaments). Collateral ligaments run down the sides of the knee and prevent the sideward displacement of the knee. Cruciate ligaments form an “x” down the centre of the knee and are primarily concerned with controlling the front and back movement of the knee.²

Cartilage includes hyaline and fibrocartilage. These allow the smooth movement of bones, reduce damage due to friction, and enable shock absorption.

Tendons are tough bands of connective tissue, similar to ligaments, but with the function of connecting muscles to bones. The patellar tendon is the biggest tendon of the knee joint. Interestingly, it is actually a misnomer. The patellar tendon connects two bones (patella and tibia), thus acting like a ligament.³ It is believed that the patellar tendon is a continuation of the quadriceps (thigh muscle) tendon directly above it, hence its misleading name.

Causes of patellar tendonitis

Common risk factors for patellar tendonitis include:^3,7

• Overusing your knees due to repetitive movements such as jumping or running
• A sudden increased load on the knee joint caused, for instance, by abruptly starting high-intensity sports without proper conditioning
• Activity on hard surfaces (higher impact)
• Weakening of the knee joint due to age, especially after 40 years old
• Weak, or tight thigh muscles. A constant state of tightness makes the tendon more susceptible to inflammation
• A sudden increase in body weight. This places more strain than usual on the muscles and knee joints, leading to eventual inflammation
• Certain conditions that may cause tendon weakness (and thereby increase susceptibility to inflammation), such as rheumatoid arthritis, metabolic disease, infections, diabetes or high cholesterol
• Medications like corticosteroids, which have been linked to tendon weakness 
• A history of surgery around the knees (e.g. knee replacement), which renders these structures more vulnerable to inflammation

Symptoms of patellar tendonitis

Pain is usually progressive. It starts as a dull ache on top of the shin, under the kneecap. Over time, under continuous load, pain may become sharp and severe.

Some key symptoms of patellar tendonitis to keep in mind include:

• Pain at the site of the tendon, which may worsen when loading the tendon due to standing from a seated position or moving
• Cracking/popping sounds or sensations arising from the knee joint
• Stiffness while moving the knee joint

It is also important to be aware of possible causes of patellar tendonitis: sudden pain after changing playing surfaces, footwear or increasing exercise intensity may indicate patellar tendon inflammation.

How is it diagnosed?

Like most orthopaedic conditions, patellar tendonitis is diagnosed via clinical and radiological techniques:³

• Medical history - The clinician will usually start by collecting a detailed medical history, particularly about physical activity and conditioning. It is important to be accurate when giving your history to help the clinician reach an accurate diagnosis
• Palpation - The clinician may then press around the area under the knee to elicit pain. This is done to confirm the location of inflammation and check for any swelling and visible redness
• Imaging - Finally, the clinician may recommend getting an X-ray to rule out any other potential causes and confirm the diagnosis. If severe damage is suspected, magnetic resonance imaging (MRI) can also be recommended to assess the damage caused to the patellar tendon

Home remedies

Note: Remedies in this section should not be considered medical advice. Kindly consult your physician for a professional opinion.

The first step while seeking to remedy a condition is to identify its potential cause and eliminate it. Whether the remedy involves a change of playing surface, a change of footwear, or a change in the training regimen, try switching back to the old equipment/regimen after the pain subsides. If there has been a change in medication, consult your physician immediately. Other steps for home management of patellar tendonitis include:

RICE – The RICE method is a common management strategy for soft tissue injury. It consists of the following steps:

• Rest – Avoid using the injured part. Intense physical activity, sports and using new equipment should be avoided until the pain subsides
• Ice – Apply ice over the area to reduce inflammation
• Compression – Compress the area using a compression bandage to reduce excess blood flow and inflammation. Care should be taken not to wrap the bandage too tightly and cut off blood supply altogether
• Elevation – Elevate the knee using a pillow or towel to reduce discomfort

Over-the-counter anti-inflammatory medication (oral or topical) – This can be used to reduce pain and discomfort. However, this provides only temporary relief and is not a permanent solution – the risk factor should be identified and eliminated to cure the condition.³

Prevention

Some measures that can be taken to prevent injury include:

• Taking it slow: When increasing the intensity of physical activity, make sure proper conditioning has been done before to avoid patellar tendonitis and other relevant injuries
• Always warm up prior to exercise
• Ensuring that all equipment, especially footwear is proper. Try changing equipment as soon as symptoms are felt

Treatment options

Along with home remedies and rest, clinicians may recommend some of the following treatment modalities:

• Anti-inflammatory medication
• A knee brace to support the knee
• Physical therapy to improve the strength and flexibility of the tendon
• Surgery If the tendonitis progresses to a tendon rupture/tear, reconstruction surgery may be required

FAQs

I am not an athlete. Could I suffer from patellar tendonitis?

Yes, although more common in athletes, patellar tendonitis can affect regular people. Possible causes include a sudden increase in weight, change in footwear or weak/tight tendons.

Can patellar tendonitis be treated at home?

Yes, conservative home remedies can have a high success rate, especially during the early stages of the condition.⁸ This makes prompt detection and action essential.

When should I reach out to my physician?

Consider reaching out to a physician when home remedies have stopped improving the condition. It is important not to expect instant results (unless taking medications), as this is a chronic condition which requires time to heal.

What are the complications of patellar tendonitis?

If left unmanaged whilst continuing with rigorous physical activity, microdamage may eventually progress from tendonitis to a tendon tear/rupture.

I think I have patellar tendonitis. Do I need to get surgery for the condition?

Unless the condition is extremely severe (tendon rupture), the likelihood of getting surgery is rare. However, it is important to consult a trained specialist who can confirm the diagnosis and suggest a treatment plan tailored to your individual case.