Jumper's Knee

Introduction

Patellar tendonitis, or jumper’s knee, is an inflammation of the patella tendon in the knee, also known as Sinding-Larsen-Johansson syndrome.  The patellar tendon connects the patella to the tibia (or the kneecap to the shin) and it is a common injury, especially amongst adolescent athletes.  It is caused by an increase in tension and pressure during contraction of the quadriceps muscles pulling against the lower pole of the patella and is most common in those participating in high impact sports such as running, jumping and hurdling [1].

Who is most affected?

Signs and symptoms

Despite patellar tendonitis being caused from high impact activities, it primarily affects adolescents between ages 10-14 (predominantly males) undergoing rapid growth.  It is characterised by pain and tenderness below the kneecap, most often accompanied by swelling, particularly after load has been placed through the knee.

If left untreated it can cause cartilage damage, resulting in pain and permanent damage to the pole of the patellar.  However, continuous low-level pain and tenderness below the kneecap is the most common symptom and can be easily treated if caught early.

If left acute pain can develop along with swelling, particularly after load has been put through the knee joint, after sports such as basketball, running and other athletic events.

Causes and risk factors

The most common cause of patellar tendonitis comes through participation in sports, especially those sports involving frequent load placed through the knee; such as from frequent jumping leading to overuse of the knee joint - in sports such as volleyball, cricket and athletics.  In a 2 year study of over 2,000 runners [3], patellofemoral pain syndrome was the most common injury, however, it occurred mostly in males under the age of 34.  It is also fair to point-out that it is usually an injury borne from overuse, where athletes increase a variable such as speed or distance too quickly - the latter is most common.

Between 2008-2018 marathon participation increased by 50% worldwide, this has meant a great many first time runners, with many intent on achieving the sub-3hr marathon (as depicted in many internet blog posts).  This, in turn, leads to poor running practice and bad form and, sadly, the number of endurance athletes joining the one(race)-and-done crowd.

Injury is often easily solved, sometimes without the need for professional intervention, curtailment of activity or long recovery.  However, it is useful to get the opinion of a coach or qualified practitioner regarding assessment of posture or running gait, as simply replacing footwear or modifying a particular movement, like a deadlift or squat or how a bowler or high jumper plants their foot at the end of their run-up, can help remedy the situation quicker.

Weight-lifting often causes injury and, as well as tight quadriceps and hamstrings causing knee pain, poor technique and trying to lift too heavy a weight are often contributory factors to patellar tendinitis.

Jumper’s Knee is not just a problem for athletes or those involved in sport as patellofemoral pain can be common in teenagers undergoing rapid growth.  

This most often occurs between the ages of 9-14 or during puberty when body development can rapidly accelerate.  This increased speed of development can irritate the growth plate of the knee (the layer of cartilage towards the end of a bone where bone growth occurs) and usually persists for about 12 months or so until growth subsides and can cause considerable pain.  This form of patellar tendonitis is known as Osgood-Schlatter’s disease.

Further, during a rapid growth spurt, a ‘bump’ will often occur at the top of the shin bone - where the patellar tendon attaches to the tibia - and is far more common in males than females.  The bump may remain into adulthood and is not any cause for worry as long as the pain recedes.  If the patellar tendon is left to rest the pain should subside and, in some cases, is all that is needed for recovery.  However, should it reappear once activity is restarted, treatment should be sought.

Diagnosis

If you regularly particulate in power sports or activities that put high stress on the knee joint and patellar tendon, diagnosis should be fairly straight-forward.  However, there are a few different reasons, beyond this, that could cause patellar tendinopathy.

It is important to get the correct diagnosis as patellar tendonitis can often be mistaken for Osgood-Schlatter’s, patellofemoral syndrome, quadriceps injury, knee bursitis and other injury [4].

Jumper’s knee was not actually termed until 1973 and was characterised into 4 stages[5]:

  1. Pain after sports or physical activity
  2. Pain prior to participation but easing after warm-up
  3. Pain at rest as well as during activity
  4. Rupture of patellar tendon

Treatment

Don’t push through pain.  Your body is telling you there is a problem and blind continuation of the sport or activity that is causing it will eventually end in chronic pain, if ignored.

Rest, ice, compress and elevate is usually always the first thing to do with any injury and, if caught early, may be all you need to recover.  However, if the pain is too acute, non-steroidal anti-inflammatories, like ibuprofen, can be used to manage the pain.  Please be aware that pain management is only addressing the symptoms and does nothing to help solve the overall cause.

If an intervention, such as physical therapy, is required the hiatus in activity need not be too long.  Studies have shown rest and therapy can resolve the knee pain forever in just 3 months [2].

Further steps

Can I run with Jumper’s Knee?

After patellar tendonitis has been diagnosed, treatment needs to be taken seriously.  Whether you are able to continue running and to what degree, depends upon the severity of the injury.  Many runners may still be able to continue at a reduced workload or onto more forgiving surfaces than road tarmac.  For those who are able to do this it is important to be honest with yourself and make sure the pain is manageable and does not increase during the workout and, further, recedes within an hour of and no running, jumping or other activity that is likely to place impact through the kneecap should be undertaken.  Ignoring patellar pain can result in chronic knee pain and increases the likelihood that the patellar tendon will tear.  As stated above, rest in the first instance followed by strengthening exercise is likely to mean you only have to undergo a few weeks of relative recovery before being able to start rebuilding strength and fitness in your chosen sporting discipline.

References:

  1. Valentino, M. et. al. Sinding-Larsen-Johanssen syndrome: a case report; Journal of Ultrasound.  2012;15(2):127-129 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3558086/#bib1 
  2. Hagner, W. et. al. [A case of Sinding-Larsen-Johansson and Osgood-Schlatter’s disease in both knees]; Chir Narzadow Ruchu. 1993;58(1) https://pubmed.ncbi.nlm.nih.gov/7671663/
  3. Taunton, J. E. et al. A retrospective case-control analysis of 2002 running injuries; British Journal of Sports Medicine. 2002;36:95-101 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1724490/pdf/v036p00095.pdf 
  4. Javier, A. et al. Jumper’s Knee; StatPearls Publishing, Treasure Island. 2022 https://www.ncbi.nlm.nih.gov/books/NBK532969/
  5. Blazina, M. E. et al. Jumper’s Knee; Orthop Clin North Am. 1973;4(3):665-678 https://pubmed.ncbi.nlm.nih.gov/4783891/ 

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