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Knee Pain: Causes, Treatment, Investigations

by Josephine Andrews
Published: Last Updated on 240 views

Knee pain can have very different characteristics. Sometimes they arise suddenly and in a recognizable connection with a strain, a fall or an accident. Then there are often other symptoms such as swelling and bruising. Knee pain can also be caused by chronic joint wear and tear or various diseases. Read here what can be behind the pain in the knee and how it can be relieved.

quick overview

Knee Pain: Symptoms & Localization

Knee problems can occur suddenly (e.g. due to injuries) or gradually increase. The latter is the case, for example, with progressive wear and tear of the knee joint (knee osteoarthritis = gonarthrosis). Sometimes the knee pain is so severe that it is almost impossible to walk, stand or even sit for long periods of time. Depending on the cause, knee pain is just a temporary (treatable) health problem or a daily companion that you have to learn to live with.

When the pain occurs is also very variable and can indicate the possible cause:

  • Start-up pain (break-in pain): This is what knee pain is called, which is noticeable at the beginning of a movement in the joint and decreases with further movement. The cause is often wear and tear ( arthrosis ) of the knee joint (gonarthrosis).
  • Movement pain: If the knee pains more or less persistently during movements, this is often due to a recent injury (of tendons, ligaments, bursae, menisci, etc.).
  • Stress pain: If the knee pain only occurs when the joint is under stress, this can indicate a meniscus injury, for example. Sometimes the knees hurt, especially when they are loaded when climbing stairs. A possible cause is a certain form of bursitis (pes anserina bursitis).
  • Pain at rest: If the knee pain (also) occurs at rest, the reason could be rheumatoid arthritis.

Depending on the cause, the localization of knee pain can also be very different:

  • Knee pain on the inside of the joint, for example, can be caused by damage to the medial meniscus. Pes anserina bursitis also causes pain on the inside (or slightly below) of the knee.
  • External knee pain can be caused by damage to the lateral meniscus. But there are also other possible causes. For example, a so-called “runner’s knee” can be present: This is a painful irritation of the fiber cord that runs from the outside of the thigh to the shinbone. Passionate runners are particularly affected.
  • Anterior knee pain is often grouped under the terms Patellofemoral Pain Syndrome or Femoropatellar Pain Syndrome. The triggers can be very different (incorrect and excessive strain, injury or malformation of the kneecap, injury or inflammation of the bursa in the front knee area, etc.).
  • A Baker’s cyst can be one of the factors responsible for pain in the hollow of the knee . This is a fluid-filled cavity in the back of your knee.

Depending on the cause, knee pain is often accompanied by other symptoms ( accompanying symptoms ). For example, inflammation-related pain in the knee can be accompanied by swelling, redness and overheating in the joint area. If the knee pain is associated with increasingly limited mobility of the knee joint, the cause is usually progressive joint wear and tear (knee arthrosis). The symptoms often intensify in cold and wet weather (“weather sensitivity”).

Knee Pain: Most Common Causes

Knee pain can have many different causes. In addition to injuries, this also includes overuse and incorrect strain on the joint. However, pain can also arise if a knee joint is not used enough and the associated muscles are untrained. In addition, knee pain can be caused by wear and tear, metabolic disorders, autoimmune diseases and infections.

Injuries as a cause of knee pain

An injury to the cartilage, ligaments or menisci is often the reason for knee pain. Such injuries do not only occur in sports or during hard physical work. You can also injure your knee in everyday life. Above all, the combination of bending and twisting as well as sudden stopping movements with increased shearing forces are risky for the knee joint. Here is an overview of the most important injuries:

  • Bruises are a common cause of knee pain. A bruise usually occurs outside of the joint capsule as a result of an impact, blow or fall. The skin in the affected area turns bluish-red.
  • Strains are overstretching of muscles, ligaments, the capsule or the tendons around the joint. They become noticeable through bruising and pain. In addition, the affected knee feels less stable for the patient for a time.
  • Muscle and tendon tears in the knee joint usually only occur in otherwise healthy people when the force is applied – and therefore particularly often in athletes. Collateral ligament, tendon attachment or patellar tendon tears are usually accompanied by bruising and severe functional limitations as well as loss of stability.
  • Meniscus tears are often caused by the combination of flexion and rotation in the knee joint. The meniscus can partially or completely tear off the shin roof. The patients develop the typical “meniscus pain” and an often bloody joint effusion. If part of the meniscus is displaced into the joint space as a result of an injury, the knee joint no longer functions properly. It can even be completely blocked. Tear injuries particularly often affect the meniscus on the inside of the joint (internal meniscus).
  • Severe shear forces in the knee joint can cause a cruciate ligament rupture . Stopping movements, changes of direction or external violence (as in football) are particularly dangerous. If these movements and forces cannot be absorbed by the surrounding muscles because they are too sudden or too strong, a cruciate ligament can tear. The anterior cruciate ligament is most commonly affected.
  • One speaks of a kneecap dislocation ( patella luxation ) when the kneecap jumps out of its guide. This can result in severe knee pain, bruising, tears in the kneecap ligaments and damage to the cartilage.
  • Broken bones can also be the cause of knee pain. The injury can affect the head of the shinbone, the condyles of the thighbone, or the kneecap. A bone injury can also occur with a cruciate ligament tear if a piece of the bony anchorage tears out.
  • Open wounds such as abrasions or cuts are common and mostly harmless knee injuries. If the injuries are deeper, there is an increased risk of infection. If the doctor suspects an injury to the joint capsule in a patient and thus an opening of the joint interior, an operation must be carried out immediately.

Inflammation as a cause of knee pain

Sometimes knee pain is caused by a non-bacterial inflammatory disease of the joint. These include rheumatic diseases and certain metabolic disorders that attack the inside of the knee joint:

  • In chronic rheumatoid arthritis (chronic polyarthritis), which usually occurs in phases, immune cells attack the synovial membrane. This becomes inflamed and produces inflammatory substances that destroy the connective tissue and articular cartilage.
  • Bechterew’s disease (ankylosing spondylitis) also belongs to the group of rheumatoid diseases. Here, in addition to inflammation, there is increasing curvature of the spine . Patients usually try to compensate for this curvature by bending their hips and knees. Knee pain is one of the possible consequences.
  • Osteoarthritis refers to the wear and tear of the joints. The cartilage covering the joints gradually wears away until finally the bones rub against each other without protection.
  • In gout , the uric acid level in the blood is greatly increased. The excess uric acid then deposits in salt crystals in the joints (like the knee joint), irritating and damaging the synovium and cartilage. Gout in the knee often manifests itself in spurts with very painful swelling and overheating.
  • In pseudogout (chondrocalcinosis), calcium salt crystals form and are deposited in the cartilage. This often has consequences similar to the accumulation of uric acid crystals in gout.
  • Reactive arthritis (formerly: Morbus Reiter or Reiter ‘s syndrome) is another representative of the rheumatoid group. It is an inflammation that can occur after certain bacterial infections of the gut, urinary tract or genitals. It can cause knee pain, among other symptoms.
  • Rheumatic fever is caused by certain bacteria , a type of streptococci. It can affect the knees and other joints, as well as the heart , kidneys, and nervous system.
  • Systemic lupus erythematosus is an autoimmune disease, i.e. a disease in which the immune system attacks the body’s own cells . So-called immune complexes are formed from antibodies and the attacked cell structures. Among other things, they can be deposited in the knee, which can lead to painful inflammation of the synovial membrane.
  • Psoriatic arthritis also belongs to the rheumatoid group. It is a chronic joint inflammation that occurs in connection with psoriasis (psoriasis) . If the knee joint is affected, the resulting knee pain gets progressively worse. But there are also longer symptom-free phases.

Other causes of knee pain

  • The so-called parapatellar pain syndrome (chondropathia patellae) is quite common. Those affected feel pain in the kneecap area. The reasons for this are often unclear. Sometimes there is a misalignment of the kneecap or an inflammation of the tendons or bursa.
  • Tendon and bursitis can be triggered by injuries, infections or overuse.
  • Runner ‘s knee (ilio-tibial band syndrome or tractus syndrome) is often the reason for stress-related knee pain on the outside of the joint, especially in runners. The symptoms are caused by irritation of the wide, taut fiber cord that runs on the outside of the thigh and attaches to the shinbone (iliotibial band). The irritation is due to repeated misuse or overuse of the knee.
  • A fold of mucous membrane on the back of the kneecap (plica mediopatellaris) slides constantly over the articular cartilage during joint movements. Over time, this can cause cartilage damage and thus pain in the knee.
  • Likewise, softening of the cartilage behind the kneecap (chondromalacia patellae) as an early form of cartilage wear can cause knee problems.
  • Osteochondrosis is a disorder of bone formation in children. They occur during the growth phase and are noticeable, among other things, through knee pain.
  • Osteonecrosis refers to the death of a section of bone . It can be caused by a septic (caused by bacteria) or aseptic feeding disorder of the bone. Examples of aseptic osteonecrosis are Osgood-Schlatter disease and Ahlbaeck disease. Injuries can also lead to osteonecrosis if bone nutrition is disrupted.
  • The term Baker’s cyst refers to protuberances of the posterior joint capsule that passes between the muscles of the popliteal fossa. A Baker’s cyst usually manifests itself as a soft swelling in the back of the knee and pain in the back of the knee.
  • Functional disorders in the hip joint can lead to pain in the knee. Either the pain actually originates in the hip and only radiates to the knee. Or the disturbance of the hip function impairs the movement chain and causes incorrect loading of the knee. This can cause knee pain over time.
  • Haemophilia is a hereditary disease in which blood does not clot properly. This can lead to sudden joint bleeding, among other things.
  • Malignant, but also benign tumors can also be the cause of knee pain. They can occur in bones, fat or connective tissue, in blood vessels or in the synovial membrane.
  • Occasionally there is a psychosomatic cause behind chronic knee pain .

Risky sports

Knee pain is often caused by sports injuries. Sports with abrupt stop movements and changes of direction are particularly risky, as are those in which the knee is bent and rotated under high loads. These include, for example, football, handball, hockey and alpine skiing. But strength sports often lead to painful bruises, ligament strains and damage to the meniscus or cruciate ligament.

Swimming can also cause knee pain. This is how the so-called swimmer’s knee develops, for example when swimming the breaststroke, through repeated rotary movements in the knee joint. Fins increase the stress on knee and ankle joints. Turning in the pool (roll turn) in competitive swimmers also puts a strain on the knees and can cause knee pain.

Knee pain: when do you need to see a doctor?

As a patient, you can usually treat obvious reasons for knee pain such as superficial abrasions, minor bruises or strains of the knee joint yourself and without medical help. For deeper wounds , however, a doctor’s visit is urgently needed. This is especially true if the joint capsule may have been injured. Then there is the danger that germs have unhindered access to the interior of the joint. If such infections and serious joint injuries are not treated, the joint function can be partially or completely lost – the joint can become stiff.

You should also see a doctor if you have damaged menisci, ligaments, or cartilage in the knee .

Knee pain should also be checked out by a doctor in the following cases:

  • The knee pain is very strong .
  • The cause of the pain is unclear .
  • The knee pain lasts for several days (despite rest, heat or cold treatment, painkillers, home remedies, etc.) or progresses in phases .
  • Knee pain is accompanied by other symptoms such as redness, swelling and overheating of the joint, bruising, restricted mobility of the joint or fever.

Knee pain: investigations

If a doctor wants to get to the bottom of the cause of knee pain, he will first collect important information from the patient. In this conversation to collect the medical history (anamnesis), the doctor asks, among other things, how long the pain has existed and whether there is a probable trigger (such as an accident, physical exertion). The exact location of the knee pain (inside, outside, etc.), its course and any underlying diseases (such as rheumatic diseases or metabolic disorders) are also important for the diagnosis.

The doctor will also inquire whether the patient has already tried any therapy (bandages, cooling, pain ointments, etc.) and how well they worked.

Physical examination

During the physical examination, the doctor tests how far the affected person can flex the knee joint under their own power (active flexion) and how far it can be flexed without pain with help (passive flexion). He feels the tendons and ligaments in the knee area for any abnormalities (palpable injuries, tenderness, etc.). An important function test for the cruciate ligaments is the drawer test: If the head of the tibia can be pulled forward in relation to the femur, the anterior cruciate ligament is unstable (torn). If you can push the tibial plateau backwards in relation to the thigh, the posterior cruciate ligament is damaged.

The doctor may also ask the patient to walk up and down a few steps to assess gait. For example, movement restrictions and protective postures become visible.

Imaging studies

Imaging examinations are often necessary to clarify knee pain:

  • An ultrasound examination can, for example, detect major damage to tendons and ligaments or a knee joint effusion.
  • Using an X-ray examination , the doctor can detect broken bones or deviations in the position of the joints and assess the thickness of the articular cartilage. Certain bone deformations typical of arthrosis or inflammatory joint diseases are also visible on the X-ray image.
  • Computed tomography (CT) uses an X-ray beam orbiting the patient to create detailed tomographic images of the knee joint. Many changes inside the joint can be recognized in this way.
  • Another tomography method, magnetic resonance imaging (magnetic resonance imaging or MRI), is particularly well suited to detecting hidden damage to ligaments, tendons or menisci inside the knee joint. No X-rays are used in the examination, but rather strong magnetic fields.
  • scintigraphy is a nuclear medicine examination. The metabolic activity of various tissues is made visible with the help of radioactively labeled substances. As a result, inflammations, but also dead bone tissue, can often be seen.

Further investigations

The doctor may order further tests:

  • Sometimes an arthroscopy is necessary in order to be able to precisely assess damage to the knee joint The doctor inserts a flexible instrument equipped with a small camera (endoscope) into the joint through a small skin incision. Small knives or forceps can be advanced at the same time via parallel working channels, with which damaged cartilage or an injured meniscus can be smoothed, sewn, glued or removed. Even larger operations on the knee joint can already be carried out using an endoscope.
  • An angiography is an X-ray examination of the blood vessels . The patient is injected with a contrast medium that makes the vessels clearly visible on the X-ray image. Circulatory disorders or dead bone parts (osteonecrosis) can be proven to be the cause of knee pain .
  • blood test can indicate infections, autoimmune or rheumatic diseases. Metabolic diseases such as gout can also be detected using blood values.
  • Urine or stool tests are carried out in particular to detect germs (such as bacteria), since some pathogens can lead to an inflammatory reaction within the joint.
  • In some cases, an examination of the synovial fluid is useful. It is checked whether the liquid has a pathologically altered composition or whether it contains bacteria or antibodies.
  • If rheumatic fever is suspected, a throat swab is taken and analyzed in the laboratory.
  • Examinations of the skin provide indications of possible psoriatic arthritis.
  • If a benign or malignant tumor is suspected, tissue removal ( biopsy ) may be required.

Knee pain: you can do it yourself

In the case of acute injuries to the knee joint, the first thing to do is to relieve the joint, relieve the pain and counteract swelling. Orient yourself to the so-called LUCKY rule: rest, ice, compression, elevation . The cold causes the blood vessels to constrict and a bruise stops growing. Elevation also reduces blood flow to the injured area. You can also stabilize the knee with a tight bandage (compression).

If the knee pain is due to irritation or inflammation of the tissue or a bruise, sports ointments and taking enzyme tablets can have a supportive effect. An enzyme from the pineapple fruit, for example, has an anti-inflammatory and decongestant effect. Curd envelopes have also often proven to be anti-inflammatory and pain-relieving (because they cool) . However, if the knee pain is associated with a rheumatic disease, warmth can be felt to be more pleasant than cold.

If necessary, you can also use painkillers for knee pain . In the pharmacy you can get over-the-counter preparations from the group of non-steroidal anti-inflammatory drugs (NSAIDs) such as acetylsalicylic acid (ASA), ibuprofen , naproxen or diclofenac . They have a pain-relieving and anti-inflammatory effect. Ask a doctor or pharmacist for advice on the choice of painkiller, dosage and use.

Knee protection for prevention

Suitable footwear, special knee pads and possibly knee bandages (the latter are advisable for sensitive people who, for example, have had knee problems before), offer a certain degree of protection against knee injuries. However, you should only use these if they are absolutely necessary – for example during training, games or competitions.

Regular and balanced training of the entire musculature around the knee joint is more important for the prevention of knee injuries. Strong muscles stabilize the knee joint and can often prevent knee pain.

Knee pain: treatment by the doctor

Effective pain management is very important in the treatment of knee pain. The doctor will recommend or prescribe a suitable painkiller for the patient. In doing so, he takes into account any contraindications (contraindications) – i.e. circumstances that speak against the use of a specific drug. For example, people with a stomach ulcer should not take painkillers from the NSAID group (such as ASA or ibuprofen).

Further treatment of knee pain depends on the cause. For example, if the pain is related to an open injury , this is surgically cleaned and, if necessary, closed. Due to the high risk of infection for the knee joint, special care is important.

A puncture can provide relief in the event of blood or irritation in the knee . The accumulated liquid is drawn off with a hollow needle.

With some injuries, the pain in the knee can be relieved with bandages or special splints . At the same time, the range of motion of the joint is restricted. This allows the damaged structures to heal in peace.

Depending on the cause, the doctor can also prescribe physical and physiotherapeutic treatments for knee pain. These include, among other things, ultrasound or electrical stimulation therapy, medicinal baths, manual therapeutic grips and physiotherapy exercises.

If other diseases are the cause of knee pain (rheumatism, psoriatic arthritis, etc.), these must be treated separately.

Knee pain: how it occurs

Basically, pain in the knee is a warning sign that should be taken seriously: the pain often signals that the knee should not be put under strain. In the case of knee pain caused by wear and tear, however, the opposite often applies: Too much protection of the painful joint can even damage the knee.

Incidentally, not all damage to the knee manifests itself as classic joint pain . For example, pain in the hollow of the knee can also be an indication of damage to the knee joint or its connective tissue capsule.

Sometimes pain radiating from the knee is felt elsewhere (such as the surrounding muscles). Conversely, supposed knee pain can have its cause elsewhere: For example, damage and injuries in the hip joint or in the spine can radiate downwards and express themselves as knee pain.

It is therefore very important to understand the basic structure and function of the knee and to find out the cause even if knee pain is unclear.

This is how the knee is constructed

Along with the hip and shoulder joints, the knee is one of the most complex and largest joints in the body. It works mechanically like a cantilever hinge. However, due to its sophisticated internal structure, it also offers a certain amount of leeway for slight twisting around the longitudinal axis.

Strictly speaking, the knee consists of two individual joints :

  • the large, load-bearing joint between the thigh bone ( femur ) and shinbone ( tibia )
  • the joint between the kneecap ( patella ) and the thigh bone that is decisive for the transfer of force.

Ligaments and tendons give the knee joint support and guidance. The so-called cruciate ligaments (one at the front and one at the back) and lateral ligaments on the outside and inside tightly connect the upper and lower leg bones.

The joint is sealed off from the outside by a covering of connective tissue ( connective tissue capsule ). Doctors therefore differentiate between damage or injuries inside (intra-articular) and outside of the joint (extra-articular).

Muscles and ligaments provide stability

Muscle power acts on the joint at the front via the strong patellar tendon and the kneecap. Smaller tendons from the hamstring muscles attach to the shinbone behind the knee. Smaller muscles work in the opposite direction: they pull from the rear tibia to the femur. All muscles and ligaments together serve both the movement and the stability of the knee joint.

menisci and bursa

Inside the knee, on top of the tibia bone, are two crescent-shaped cartilage disks called menisci . As a buffer, they absorb shock and pressure loads in the knee and distribute them evenly in the joint. In addition, they ensure that nutrient-rich joint fluid (synovial fluid) is evenly distributed over the articular cartilage.

There are also bursae in the knee. These fluid-filled connective tissue cushions sit in places where there is particularly high pressure and friction.

Both menisci and bursae are common causes of knee pain when there is inflammation or injury .

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