Jumpers knee

The jumper knee often affects jump athletes, is caused by overstressing the kneecap tendon and leads to stress pain in the front of the knee. You can find out more about causes, diagnosis and therapy here

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The jumper knee is one of the most common knee problems in jump athletes

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Jumper's knee - in short

A jumper's knee is an overload of the kneecap tendon (patellar tendon). It can occur especially in sports with jumping loads or rapid changes of direction. The main symptom of the jumper's knee is pain, which initially occurs after a sporting activity. In the course of time, however, the pain can persist during sport or during everyday movements. Eventually, the kneecap tendon can even tear. A jumper's knee is diagnosed through the medical history and the orthopedic examination, imaging methods are only used for special questions or for surgical planning. A jumper's knee is treated primarily through consistent relief (sports break). Physical therapy methods, anti-inflammatory drugs, knee wraps and tapes and special exercise treatments (eccentric strength training) are also used (so-called conservative therapy). If there is no improvement within six months or if symptoms recur after doing sports, surgical treatment by means of arthoscopy may be an option.

What is a jumper knee?

Overloading the kneecap tendon (patellar tendon) causes the smallest injuries and fraying of the tendon at its origin at the lower edge of the kneecap. New connective tissue forms nearby, and nerves and blood vessels sprout. Doctors also speak of degenerative changes. The general technical term is tendinopathy (= tendon disease). Overloading of the patellar tendon occurs primarily through sporting activity, especially in so-called high-speed sports with rapid changes of direction, abrupt braking ("stop and go") and heavy loads when jumping and landing such as volleyball or handball. Hence the term jumpers knee. One or both knees can be affected. Usually the tendon at the lower pole of the kneecap is affected (insertion tendinosis).

Tendinopathies, i.e. pain in the tendons, can occur in different places. The jumpers knee is an inflammation at the insertion of the tendon (insertion tendinosis) at the lower pole of the kneecap. This occurs especially in sporty adults. If the symptoms already occur in the adolescent, it is usually Sinding-Larson-Johansen's disease. Here, too, overstressing causes inflammation at the origin of the patellar tendon, but part of the kneecap can die with it (osteonecrosis).

Background information - The knee joint

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TO THE PICTURE GALLERY

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The knee: More than a joint

The knee joint connects the thigh and lower leg. It is the largest and probably the most complex joint in humans. The knee joint can be bent and stretched, and also rotated slightly when in a bent position. It is exposed to great stress and at the same time has to offer sufficient mobility. The knee joint is made up of the thighbone (femur), the shinbone (tibia) and the kneecap (patella). The thigh bone and the shin are covered with cartilage tissue, the joint gap is only a few millimeters. The knee joint is stabilized by the surrounding capsule, several ligaments (lateral collateral ligaments, anterior and posterior cruciate ligament), two menisci (sickle-shaped cartilage discs in the knee joint gap) and numerous muscles. In this way, the knee can withstand the enormous pressure loads that act on it: when jumping, for example, up to twenty times the body weight.

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Part 1 of the knee: the kneecap joint

The kneecap (patella) sits like a cap at the front of the knee, easy to feel and see. It is an almost triangular, pointy bone that is about two to three centimeters thick, about twice as wide and just under four centimeters high. Its back is embedded in a groove in the thigh bone and thus forms the kneecap joint (femoropatellar joint).

At the front it is interwoven with the tendon of the thigh extensor muscle. With the help of its cartilage coating on the back, the kneecap moves several centimeters up and down when the knee is bent and extended. It is a kind of spacer and increases the leverage of the thigh. It also guides the kneecap tendon like a "rider" and makes it easier for it to slide over the bone.

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Part 2 of the knee: the popliteal joint or femorotibial joint

The second partial joint of the knee, the popliteal joint (femorotibial joint), is located between the thigh bone and the head of the tibia. Due to its mechanics, it also supports rotating movements in the bent position.

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Kneecap ligament

The patella ligament is about two centimeters wide and very strong. The tendon acts as a ligament in the sense of connecting two bones. As part of the knee joint capsule and to a certain extent a continuation of the tendon of the thigh extensor, it runs from the lower edge of the kneecap to the shin bone. It connects the thigh extensor muscle to the shinbone via the kneecap and transmits muscle power.

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Teamwork for the knee

In addition, an important auxiliary apparatus stabilizes and guides the knee joint: the two cruciate ligaments and two collateral ligaments, the joint capsule made of connective tissue, the joint cartilage, the joint bodies (menisci, see above) and no fewer than 13 thigh muscles, including the already mentioned powerful thigh extensor muscles (knee extensors or Quadriceps muscles) in the front and the knee flexors in the back.

The two menisci of each knee - the inner and outer meniscus - consist of connective tissue and elastic cartilage. They compensate for differences in shape on the joint surfaces between the thigh rollers and the tibia plateau, act as shock absorbers and protect the joint cartilage. In this way, they stabilize these important parts of the knee joint. They also increase the area over which pressure can be transferred.

Thanks to several bursa, which are not present in the same number on the knee in all people, muscles and tendons can slide more easily on the bony surface. The buffers are close to the joints under the skin, over protruding bones, including over the kneecap, under tendons, ligaments and muscles.

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Causes: How does a jumper knee come about?

The jumper's knee is one of the orthopedic overload syndromes. Syndrome stands for a clinical picture with several, more or less typical symptoms. Both the intensity and the type of load play a decisive role in the knee problem. Heavy loads caused by too intensive, too frequent or unfamiliar training in sport and movement sequences with rapid changes of direction, jumps and abrupt braking (stop and go) lead to the smallest damage and fraying of the kneecap tendon. Doctors also speak of degeneration here. Initially, there is a disruption of the blood circulation in the tissue, and an accompanying inflammatory reaction can also occur. Not only abrupt tensile loads when jumping, but also when landing after the jump are unfavorable. The sliding tissue around the tendon can also enter the process of wear and tear. If the strain is sustained, the micro-injuries can also result in a tendon tear.

A jumper's knee is particularly common in these sports:

  • basketball
  • volleyball
  • Handball
  • high jump
  • Long jump

Occasionally, a jumper's knee also occurs in competitive athletes in the following disciplines:

  • Soccer
  • Weightlifting
  • squash
  • Jogging on hard surfaces
  • Bodybuilding
  • tennis
  • To go biking

In addition to jumping sports, by far the most important causes of the jumper's knee, certain other risk factors on the knee itself can promote tendon damage, such as shortening of the thigh muscles, connective tissue and ligament weakness, a hereditary elevation of the kneecap, misalignments such as knock-knees and bow-legs, and differences in leg length . Overweight or obesity (obesity) also puts a strain on the knees. Drugs such as statins and quinolone-type antibiotics can cause tendon damage, including the kneecap tendon. If an overload injury is ruled out, one does not speak of a jumper's knee, but rather of a tendinopathy (tendon disease).

Symptoms: What symptoms does a jumper's knee cause?

The smallest degenerative damage to the tendon can initially go unnoticed; they would only be recognizable as tissue.When symptoms occur, i.e. tendinopathy, they can develop very differently. Doctors differentiate between four degrees of severity (see separate box below). In the beginning, the jumper's knee is only noticeable after a sporting activity. Stinging pain occurs on the lower edge of the kneecap, sometimes behind the kneecap or on the upper edge (upper pole) of the kneecap, which increases when the patient is exerted. After sitting for a long time, the feeling of stiffness can also set in. The tendon is also painful when touching the lower edge of the kneecap. It can swell. With continued stress and damage, the symptoms become more persistent. They occur during exercise and persist for a longer period of time. Sports activities can be arduous or even impossible in the long run. Everyday movements, such as climbing stairs, often cause problems. Eventually, the kneecap tendon can tear.

Depending on the duration and extent of the damage, four degrees of severity are distinguished in the jumper's knee:

  • Grade 1: knee pain only occurs after exercise; this is possible to the full extent.
  • Grade 2: the pain occurs during and after exercise; but the athletic performance is still good to satisfactory.
  • Grade 3: Increasingly, the pain complicates the sporting activities, as it persists not only during, but also for a long time afterwards. They may also hinder everyday movements.
  • Grade 4: A tendon rupture (generally painless) has occurred. Then the kneecap moves upwards and the knee cannot be straightened against resistance. If the knee is not too swollen either, you can feel that the ligament is missing. The knee usually has to be operated on.

Diagnosis: How is a jumper's knee diagnosed?

The doctor primarily diagnoses a jumper's knee clinically. In doing so, he first assesses the symptoms and their development, as the patient describes them, as well as his information about sporting activities and any previous knee problems or injuries (so-called medical history or anamnesis). This is followed by an orthopedic examination of the knee joint. It is checked whether the kneecap tendon is tender at its origin or whether a swelling can even be felt here. In addition, the doctor checks the position and mobility of the kneecap in its plain bearing and its condition. He also tests the stability of the ligaments on the knee and the muscle strength and tension on the thigh. The spine, hip joints and feet are also examined, as they statically influence the knees. Last but not least, the doctor checks the muscle reflexes and scans the arterial pulses.

If the patient feels pain when he actively extends the knee against resistance, this also indicates a jumper's knee. This fits when the pressure pain subsides in the flexion position.

No routine imaging is required. With an ultrasound examination, a degeneratively changed kneecap tendon can be shown, but less the extent of the damage, for example a partial tear.

However, this works very well with magnetic resonance imaging (MRI). It is primarily indicated to coordinate diagnosis and therapy as effectively as possible, for example in competitive sports, and also before an operation to precisely determine the damaged area.

Other imaging methods such as x-rays, computed tomography (CT) or scintigraphy are only used for special questions.

Therapy: what does the treatment look like?

The choice of therapy depends on the one hand on the severity of the jumper's knee (see separate box above) and on the individual athletic requirement profile. A distinction is made between conservative (i.e. without surgery) and surgical care.

  • Conservative therapy

The most important cornerstones of conservative therapy are a break in sports or at least a switch to gentler movements, physiotherapy (exercise treatment, massages, electrotherapy and cooling) supplemented by special training therapy (eccentric strength training, see separate box). If necessary, pain relievers and anti-inflammatory drugs can also be used.

  • Sports break

The need for a shorter sports break is often difficult to convey to competitive athletes in this phase 1 of the tendon disease and even with a severity level 2. However, it is strongly recommended and should precede exercise therapy. In this phase (1 and 2), the kneecap tendon should not be overburdened by sport. In other words: You should definitely refrain from movements that aggravate the discomfort. From severity level 3, a sport break is unavoidable. However, absolute immobilization of the knee should be avoided, as it would otherwise become more immobile or even stiffen.

If necessary, the therapists develop programs for competitive athletes that enable immediate exercise training while protecting the kneecap tendon.

  • physical therapy

In addition to "classic" physiotherapy, massages, cold applications and electrotherapy are also used. In addition, special tapes or bandages can help to immobilize the tendon and relieve the power transmission.

Treatment with shock waves (so-called extracorporeal, externally applied shock wave therapy (ESWT) with bundled sound pressure waves) is rather unsuccessful in the jumper's knee.

  • Medical therapy

A temporary intake of pain reliever and anti-inflammatory medication such as ibuprofen or paracetamol can be useful and is determined with the doctor. Injecting cortisone into the damaged tendon should be avoided at all costs, as this can cause the tendon to tear.

More recently, patches that contain nitroglycerin (paired with training therapy) have also been used.

  • Operative therapy

If the pain does not subside despite intensive treatment, doctors advise those affected, especially competitive athletes, to have an operation. It can be minimally invasive arthroscopically, i.e. by means of a joint mirror.

The kneecap tendon can be loosened or notched lengthways at the tip of the kneecap (patellar tip), and newly formed connective, vascular and nerve tissue, which plays a role in the development of pain, can be removed (electrothermal denervation of the area around the tendon). The measures only affect individual fibers around the pain point and pain receptors (nociceptors) to calm them down or switch them off. Unlike a tendon tear, there is no suturing of the tendons.

At the same time, any damage to other structures, such as the articular cartilage, can be repaired in all compartments in the joint.

After the operation, the knee is functionally guided with special bandages for three to four weeks. This is followed by several weeks of physiotherapy. The aim is to optimally rebuild the muscles leading to the knee and to stabilize it in order to create the conditions for resuming sporting activity. The success rates reach up to 85 percent.

Exercise Therapy: What Is Eccentric Weight Training?

This form of training plays an important role in the jumper's knee. This is understood to mean exercises in which muscle fibers - here: the thigh extensor - lengthen and build up a high level of tension. The muscle contraction set in motion counteracts this. Eccentric loads are part of every strength training, for example when a weight is lowered again. The muscle's capacity to generate strength in this way is not always specially trained.

Appropriate training also increases the muscle strength and resilience of the knee. The tendons and muscles strengthened in this way are better able to withstand stretching and tensile stress. This is important for many braking movements.

Caution: The knee pain may get worse at first. It is important to bring this to the attention of the therapist so that they can verify what is causing the pain and properly manage the training.

Prognosis: What are the chances of recovery?

The prognosis of a jumper's knee is favorable, provided sufficient rest, suitable therapies and risk-conscious behavior when returning to sport. Patience is required as the healing process takes several months. Even after successful rehabilitation following an operation, it is often possible to return to the previous sport.

Prevention: How can you prevent a jumper's knee?

The possibilities range from changing to a sport that is less stressful for the knee, targeted muscle building, proprioception training (trains the nerve receptors in muscles and joints), conditioning training, improving jumping technique during sport and warm-up exercises before sporting activities, to optimizing sport shoes.

These measures can reduce the risk of injury in general and the risk of a jumper's knee developing or deteriorating.

Prof. Andreas Imhoff

© Klinikum rechts der Isar of the Technical University of Munich / Burkhard Schulz

Our advisory expert:

Univ.-Prof. Dr. med. Andreas B. Imhoff is a specialist in orthopedics and trauma surgery, special orthopedic surgery and sports medicine. He is head of the department for sports orthopedics at the Technical University of Munich (TUM), Klinikum Rechts der Isar. His specialties include the diagnosis and treatment of diseases and injuries of the shoulder, knee, elbow and ankle, mainly with arthroscopic procedures (joint endoscopy).

Closely linked to this is his scientific work in the field of cartilage cell and tendon transplantation. Professor Imhoff has long been a board member of the German Society for Orthopedics and Orthopedic Surgery (DGOOC), board member of the German knee society DKG, honorary member of the German-speaking working group for arthroscopy (AGA; Congress President 1999 and 2017, President 2000 to 2004, Board member 1999 to 2013) as well as honorary member and Corresponding member of several orthopedic-surgical specialist societies in Europe, USA, Asia and South America. He has received various research grants in England, Canada, and the USA, as well as scientific prizes. His publications include numerous specialist articles in national and international societies.

Swell:

  • Scott A., Overview of the management of overuse (persistent) tendinopathy, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com (accessed April 19, 2019)
  • Scott A., Overview of overuse (persistent) tendinopathy, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com (accessed April 19, 2019)
  • Timothy J Von Fange, MD, Quadriceps muscle and tendon injuries, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com (accessed April 19, 2019)

Important: This article contains general information only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor. Unfortunately, our experts cannot answer individual questions.

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