What is jumper’s knee?

Jumper’s knee, also known as patellar tendinitis, is an overuse patellar tendon injury causing pain below the kneecap. This tendon connects the kneecap (patella) with the lower leg. The kneecap, quadriceps tendon, and quadriceps muscles allow you to straighten the knee. Usually, patellar tendonitis occurs when the tendon becomes inflamed from repetitive sprinting or jumping. Generally, we see this condition in sports such as basketball, volleyball, running, and football.

Ususally, tendonitis occurs close to the attachment of the patellar tendon to the knee cap, as the tendon is exposed to the highest forces here.

patellar tendonitis

Causes of patellar tendonitis  

In general, most cases of patellar tendinitis result from too much sport. An excess increase in volume or intensity of sport frequently causes the tendon to swell. This swelling leads to tendon pain and reduced performance.

Unlike Achilles or hamstring tendonitis, we think that patellar tendon changes start as a teenager and set sportspeople up for pain as an adult.

Symptoms of Jumper’s knee 

Commonly, patellar tendinitis causes pain at the site of tendon swelling right below the knee. Usually, tendon pain worsens with high-intensity running or jumping. After sport, pain right under the knee usually settles after 1-2 days. Also, pain can occur with sitting or driving. The tendon is usually swollen and tender to the touch.

Usually, a simple ultrasound confirms tendon thickening right below the knee. In addition, blood vessels often grow in the tendon. We think these blood vessels are a source of pain. Often, MRI is useful to rule out other causes of knee pain, such as kneecap arthritis,  fat pad impingement, or kneecap arthritis. 

jumpers knee on ultrasound

Patellofemoral pain vs patellar tendinitis   

Often, it can be challenging to know whether the pain is related to the patellar tendon or the kneecap (or patellofemoral) joint.

Generally, patellofemoral or kneecap pain is often not just below the knee as patellar tendonitis pain. Also, the pain usually occurs with walking, cycling, and sitting – unlike patellar tendonitis. Sometimes, taping the kneecap can improve pain and point to the patellofemoral joint as the cause of knee pain.

Patellar stress fracture vs patellar tendonitis 

We need to be cautious about diagnosing patellar tendonitis in jumping athletes. A rare cause of anterior knee pain in jumping athletes is a stress fracture at the inferior pole of the patella. Sometimes, it isn’t easy to differentiate between the two conditions. However, a stress fracture of the patella presents with pain that worsens as activity continues (rather than warms up with exercise). Therefore, treatment is rest from activity rather than loading, like in patellar tendonitis.

Jumper’s knee treatment 

In general, patellar tendinitis is a complex condition to manage. Usually, we tell sports patients that the road to recovery is long and arduous.

Overall, we use simple treatments first, including:

Avoid kneeling on the front of the knee

Limit your knee bending to 90 degrees or less in general life or exercise 

Patellar tendon taping: Some people find that wearing a band around the knee just lower than the swollen tendon reduces knee pain.

Modify activity: Often, a period of rest from sport is needed. Cross-training helps maintain fitness.

Anti-inflammatory tablets: A short course of anti-inflammatory pills such as ibuprofen will help reduce pain.

Exercise therapy:

We all agree that exercise is essential. However, you will need to perform a strengthening program with supervision. Recent studies reveal that quadriceps muscle and tendon strengthening improves pain and function.

Generally, we recommend a heavy-loading program consisting of three or four exercises targeting the various muscle groups in the leg. For example, single-leg knee extension, single-leg incline press, and reverse lunges are some exercises we recommend to build strength and reduce pain in the patellar tendon. Also, it would be best to build strength above and below the knee, including the calf and hamstring. Exercises targeting these muscles include seated and standing calf raises and hamstring curls/hip thrusters. Once you achieve good strength, you should add ‘plyometrics’ such as skipping, hopping, and running every 2-3 days.

Should you aim for strength goals in patellar tendonitis? 

Yes, we think so.

Generally, we suggest aiming for the following strength goals:

  • squat your body weight
  • 40-60kg with a single-leg knee extension
  • 1-1.5x body weight with a single-leg incline press
patellar tendonitis

What are your options for jumper’s knee when rehabbing stalls? 

In complex cases of patellar tendinitis that fail to improve with simple treatments, we try other options:

GTN patches

Recent studies suggest that applying GTN patches to painful tendons reduces pain. These patches contain nitric oxide, an essential catalyst for tendon healing. Generally, we use patches during rehab and training so that they won’t disrupt your sport.

Shockwave therapy

A shockwave machine produces soundwaves that can heal tendons. Shockwave helps tendon recovery by reducing pain and remodelling the tendon.

Collagen supplements for tendonitis 

Hydrolysed collagen supplements taken 30 minutes before Achilles tendon loading exercises show a more significant improvement in tendon pain compared to exercises alone. We recommend taking collagen supplements to enhance the effect of exercise therapy. 

Tendon Injections

Generally, tendon injections are an option in complex cases. Firstly, cortisone injections cause worsening pain and should be avoided for patellar tendonitis. Secondly, some doctors are using platelet-rich plasma injections with mixed success. A paper written by Dr Masci shows little effect of PRP in patellar tendonitis in high-level athletes. Overall, injections are not particularly effective for patellar tendinopathy.

However, a new technique called percutaneous tendon scrap shows promise. The diseased tendon’s upper and lower surfaces are scraped using ultrasound, reducing pain and allowing an early return to sport.

Is a cortisone shot for patellar tendonitis a good option?

We don’t think so. Cortisone shots for patellar tendonitis can be done with or without ultrasound. A cortisone shot for patellar tendonitis aims to reduce pain and improve knee function.

A study compared a cortisone shot to exercise and shockwave therapy. They found that patients who had a cortisone shot for patellar tendonitis did worse at 3-6 months than those who had other treatments. So, we suggest you avoid a cortisone shot for patellar tendonitis.

Is surgery an option for jumper’s knee?

Traditional surgery, where the diseased tendon is cut out, is not a good option. Studies show that the success rate of tendon excision is only 50%. However, a new procedure involving tendon scraping by keyhole surgery shows more promise, with over 80% improvement combined with rehab.

Final word from Sportdoctorlondon about patellar tendinitis 

Overall, patellar tendonitis is a complex condition to treat. First, we start with simple treatments. Then, we move on to therapies such as patches or shockwave. Injections for patellar tendonitis are unpredictable and should be avoided. However, a tendon scraping procedure shows more promise using a special blade or keyhole. Finally, traditional surgery should be avoided, but keyhole tendon scraping shows promising results. 

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Dr. Masci is a specialist sport doctor in London. 

He specialises in muscle, tendon and joint injuries.