Patellar tendinitis – also known as "jumper's knee" – causes pain at the bottom of the kneecap (patella). Sufferers notice this pain during running and other sporting activities.
The knee joint is the joint in the human body that is subject to the greatest stresses. The kneecap, known in medical terms as the patella, forms the so-called bony joint body together with the thigh bone and the tibia. The patellar tendon connects the tibia to the lower end of the kneecap. The main function of this patellar tendon is to transfer power from the lower to the upper leg. Especially during sporting activities, it is thus exposed to constant stress. It regulates the distribution of pressure in the knee joint. Should the load during walking be incorrect or too strong, this will lead to severe pain for those affected.
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According to a medical definition from 1978, patellar tendinitis is divided into four different degrees of severity:
- In grade I, sufferers have pain in the patellar tendon immediately after running.
- At grade II, they already run with pain. The pain gradually subsides during the walk, but then returns with the previous intensity.
- In grade III, sufferers have permanent pain that manifests itself both when sitting and when walking or running.
- In grade IV, the patellar tendon is completely torn, so that it is no longer possible for the affected person to extend the knee joint without assistance.
During heavy loading on the knee joint, such as running a marathon or jumping, pressure pain can occur below the kneecap. Depending on the respective degree of severity, the discomfort is only noticeable during warm-up and disappears temporarily with increasing exertion until it is felt again after the training session.
In cases of pronounced severity, the complaints become noticeable throughout the stressful situations. In particularly severe cases, the pain in the patellar tendon can be permanent (chronic). In patellar tendinitis, stretching the knee joint against resistance then often causes pain.
Patellar tendinopathy is caused by an overload of the patellar tendon due to unaccustomed, repetitive or severe tensile stresses. There are both internal and external factors that can trigger the so-called "jumper's knee".
External influencing factors
This includes the respective – mostly sporting – activities that often trigger the symptoms. The patellar tendon is subjected to maximum tensile stress especially in jumping sports, which is why sports such as basketball, long jump, high jump and volleyball are particularly likely to trigger patellar tendon syndrome. For this reason, this syndrome is also known by its colloquial name “jumper's knee”.
In patellar tendinitis, it is important how heavy or unaccustomed the load has been on the knee. Thus, patellar tendinitis can also occur in
- Playing tennis,
- Cycling or
- Jogging on hard surfaces.
Inner influencing factors
A raised patella also promotes the occurrence of patellar tendinitis, as does a congenital ligament weakness or reduced stretchability of the leg muscles.
The doctor, usually an Orthopaedist or Sports traumatologist will first ask about the patient's sporting habits. For example, jumping sports, bodybuilding or jogging on hard surfaces suggest that the corresponding complaints are due to patellar tendinitis.
The subsequent physical examination often shows a pressure pain above the tip of the patella. Another characteristic is when the extension movement of the lower leg against a resistance leads to pain in the patient. Rather rare signs of patellar tendinitis are visible swelling or redness. Some sufferers also report pain after prolonged sitting, such as after long car journeys.
In some cases, however, the knee joint may be completely inconspicuous. In this case, a tentative diagnosis can only be made through the patient's medical history.
Imaging methods for diagnosis
Sonography (ultrasound) is a simple and painless procedure for diagnosing jumper's knee. To ensure that possible changes can be correctly assessed, the doctor will always examine the (supposedly) healthy leg as well. Typical changes in jumper's knee that can be seen on ultrasound are, for example:
- inconsistent tendon structures,
- thickening of the tendons and
- irregularly confined tendon ligaments.
X-rays do not help with jumper's knee and only serve the purpose of ruling out other diseases of the knee.
With the help of magnetic resonance imaging (MRI), the doctor can localise the degenerated region very precisely. In addition, MRI is helpful for differential diagnosis. With the help of an MRI, for example, it is often possible to rule out whether the complaints are caused by knee arthrosis triggered by knee arthritis.
If the patient feels pain while running, it is advisable to interrupt or stop the exercise session and seek medical treatment. The following procedures are available to doctors and patients for the treatment of "jumper's knee":
Regular stretching of the thigh muscles can reduce the tension on the kneecap. Using a hot roller or cold applications also improves circulation in the tendon attachment area, which improves nourishment of the tendon over the kneecap.
Physiotherapeutic treatment is still possible, especially during the early stages. In this case, therapy with shock waves and ultrasound as well as electrotherapy or manual therapy is useful. The physiotherapist will first enquire about the patient's symptoms and select the appropriate treatment options according to the degree of severity of the disease and, based on this, draw up an individual treatment plan.
Aquajogging classes are a good option for those who already have pronounced pain symptoms. In the water, the heaviness of the limbs is reduced and often even jumps can be performed without pain.
To relieve pain during an acute episode, commercially available painkillers can help. However, a doctor should definitely be consulted first, if only to diagnose the exact reason for the occurrence of the pain. Furthermore, painkillers are not recommended for long-term treatment.
Surgical interventions as a treatment option
Surgical interventions in patellar tendinitis should only ever be used as a last resort to enable the patient to lead a pain-free life or to restore his/her athletic performance. In such a surgical procedure, the inflamed layer of fat around the patellar tendon is first removed. The corresponding areas of the tendon are cut out and abnormal blood vessels are sclerosed. The procedure can be performed either open or minimally invasive and under local or general anaesthesia.
The best way to prevent patellar tendinitis is to stretch the muscles regularly after running. This reduces the muscle tension in the thigh. In addition, a thorough warm-up before running and a moderate increase in training intensity over the course of the training are of fundamental importance. Likewise, it is of great importance to allow the body sufficient time to regenerate between the different training sessions - regardless of the sport.
Overweight people should also consider weight reduction. The strain on the patella tendon and the knee joints is reduced due to a lower body weight, so that complaints occur less frequently - or at least less severely.