Knee Injuries

What is the Definition of Knee Injuries?

Medical Words

Knee injuries and knee joint trauma occur when mechanical forces overwhelm the physiological performance of the knee . The injuries can affect the ligament structures, the menisci and articular cartilage. They are caused by external violence, but can also be caused by peculiarities of the physique.

What are knee injuries?

Both in the case of damage to the ligaments and in the case of meniscus ruptures, X-rays or magnetic resonance imaging are taken for diagnostic clarification, so that damage to the bones can be ruled out. See AbbreviationFinder for abbreviations related to Knee Injuries.

Movement causes mechanical stress on the knee joint. The range of motion is determined by the physique. External forces or influences from within the body can force the joint to exceed its biomechanical limits during movement.

If knee joint trauma occurs as a result of external forces, direct or indirect forces play a role. A direct force acts on the joint in the event of an impact or blow, an indirect force in the event of bending, compression or shearing. Incorrect or excessive strain can also be traced back to the nature of the physique and physiological processes.

If force acts against the plane of movement of the joint, cruciate ligaments, collateral ligaments or menisci can tear (rupture). A combined knee joint injury occurs when several of the anatomical components of the knee are affected by a rupture (“unhappy triad”).


One cause of knee injuries is the action of external forces against the joint’s plane of motion. In addition, degenerative processes and anatomical malpositions can lead to trauma to the knee. External force from a blow or impact causes bruising.

Twisting or shearing of the knee joint leads to sprains. The trauma can occur as a result of accidents in everyday life or as a result of sports injuries. Leaps, twists, and sudden stops in movement, such as when skiing or playing soccer, can damage the meniscus or tear the anterior cruciate ligament. Kneecap dislocation is uncommon in patients under the age of 20.

Rupture of the posterior cruciate ligament is possible as a result of a violent impact on the lower leg or knee. If forces act perpendicular to the natural direction of movement, tears in the collateral ligaments are possible. Degenerative signs of wear and tear on the menisci occur as a result of the natural aging process, obesity, one-sided strain with predominantly kneeling work or genetic predisposition.

Damage to the ligaments can be caused by biomechanical dysfunctions in axial misalignments (knock knees, bowlegs). Damage to the articular cartilage (arthrosis) is the result of trauma to the meniscus and ligaments or is itself due to degenerative wear and tear.

Symptoms, Ailments & Signs

In many cases, symptoms of knee injuries allow conclusions to be drawn about certain types of injury. Clear signs of a fracture of the kneecap (patella) are an axial misalignment, unnaturally high mobility and recognizable bone fragments. Signs of a dislocated kneecap (kneecap dislocation) are pain in the front of the knee and excessive outward movement of the kneecap.

A meniscus tear causes severe knee pain and swelling. A noise may be heard. The affected knee joint can only be moved to a limited extent and can no longer be fully loaded. The main problem is stretching the knee. The feeling of instability in the knee joint when walking or running is typical.

Ligaments in the knee can be pulled and tear in whole or in part. Symptoms include pain in the area of ​​the affected ligament and significant swelling. The ability of the knee to move and bear weight is restricted. If there is pain in the non-load bearing knee joint, there may be cartilage damage. Typical symptoms indicate a cruciate ligament tear.

It causes significant pain and is audible as a cracking noise. There is severe swelling and a feeling that the lower leg is shifting against the thigh. The knee is unstable and prevents safe gait. The joint can suddenly buckle. Swelling, warmth and reddening of the skin are clear signs of a bruised knee. In many cases, bruising is also visible.

Diagnosis & History

Tears in the meniscus cause pain in the joint space, which continues into the back of the knee. They are particularly strong under pressure and stress. Rotational movements of the knee are also painful. If the meniscus is pinched, the joint can become blocked. A joint effusion may be palpable.

Arthroscopy is usually performed to confirm the diagnosis. Ruptures of the cruciate ligaments cause acute pain and effusion into the joint. It bleeds immediately after the injury and causes the knee to swell considerably. Various tests are used to check whether the ligaments still offer sufficient support when the lower leg moves against the thigh.

Both in the case of damage to the ligaments and in the case of meniscus ruptures, X-rays or magnetic resonance imaging are taken for diagnostic clarification, so that damage to the bones can be ruled out.


Knee injuries can be very diverse, so the complications associated with them can also be very different. Most knee injuries result from overstretching the ligaments. If individual ligaments within the knee are overstretched, they can tear. If such a clinical picture remains untreated, various complications can be expected.

The torn ligaments can no longer heal themselves without surgery, so the pain persists. Under certain circumstances, the knee joint can become inflamed, causing an abscess to form. An abscess is a collection of pus fluid that can even cause blood poisoning in particularly bad cases. In such a case, there is an acute danger to life. In such a case, treatment by a specialist is unavoidable, otherwise the above-mentioned complications will become considerably worse.

Of course, one of the possible knee injuries is a fracture. Surgery may even be necessary, otherwise a fracture cannot heal properly or grow together. Since knee injuries can cause a wide variety of complications, it is advisable to see a doctor early on so that the symptoms do not worsen. The above-mentioned complications can only be avoided with professional treatment.

When should you go to the doctor?

The most important criterion for seeing a doctor is the extent of the injury. If there is an obvious fracture of bone substance or instability that indicates a ligament or tendon injury, the doctor is the right person to contact. The same applies to severe pain that does not go away even with cooling and immobilization. Here, too, a doctor’s visit is necessary to rule out a meniscus injury, for example. Heavy bleeding that is difficult to stop is also a reason. This applies in particular to heavily contaminated wounds and the possible need for a tetanus injection.

In many cases, a knee injury can be cured by self-treatment without a visit to the doctor. Especially in the case of children with abrasions, cleaning, covering and, if necessary, resting is often completely sufficient. It looks different when a wound has become infected. This is often easy to recognize from the classic signs of inflammation, even for the layperson. Redness, overheating, swelling and a throbbing pain are also possible signs of an infection, as is the discharge of a yellowish wound discharge. Going to the doctor is also important if there are foreign objects in the wound that the patient cannot remove himself. Contact with caustic substances or fire is also a reason to have the skin of the knee examined closely.

Treatment & Therapy

The treatment of knee joint trauma depends on the anatomical structures involved, biological age, general health and the level of activity of the patient. Tears in the menisci are treated with arthroscopy.

If patients are younger than 40 years, a suture is promising. Otherwise, the damaged tissue is removed as gently as possible. The more extensive the meniscus resection, the higher the risk of wear and tear of the articular cartilage. Cruciate ligament tears are treated both conservatively and surgically. Conservative treatment is often sufficient. The knee is supported by an orthosis and is sufficiently stable again after 6 weeks.

The bone can be punctured in the area of ​​the cruciate ligament so that stem cells can help to heal the injury. In younger, athletic patients, the cruciate ligament tear is treated surgically. The type of injury determines whether the ligament is stitched or replaced with a cruciate ligament repair. The body’s own replacement tissue or synthetic prostheses are used for cruciate ligament plastic surgery. A torn cruciate ligament on the bone is fixed with a screw or wire suture.

After a surgical procedure, the leg is stabilized with an orthosis. The ability to exercise comes gradually and is fully reached after 10-12 months. The treatment of a cruciate ligament rupture is always accompanied by physiotherapy. The focus is on strengthening the muscles and coordination training.

Outlook & Forecast

In the case of knee injuries, the prospect of healing must be assessed according to the individual circumstances. In most cases, with fast and comprehensive medical care, you will be free of symptoms after a few weeks or months. The sooner treatment takes place and the knee is sufficiently protected, the better the course of the disease.

Normally, conservative therapy is sufficient. In the case of serious injuries, an operation is necessary. This is associated with risks and side effects. If no further complications occur, a favorable prognosis can be expected.

Without treatment, the affected person often suffers from severe and increasing pain. In some patients there is a possibility of healing without further medical measures. However, this is the exception. Rather, there is a risk of permanent disturbances in joint activity, irreparable damage to bones and cartilage, and a decrease in physical resilience.

Knee injuries can lead to lifelong instability of the knee. Despite all efforts, chronic secondary diseases can occur. These trigger an unfavorable prognosis, since an increase in impairments is to be expected over the lifespan. There is also the risk of no longer being able to carry out sporting or professional activities as usual. This leads to emotional distress and increases the likelihood of mental illness.


Gentle movement sequences are learned to prevent knee injuries. The knee is protected when the angle and axis of flexion are consciously controlled during exertion. Coordination and muscle training are essential for the functionality and stability of the knee.

A holistic training of the joint is possible when cycling. Weight and eating habits are also important for knee health. Elastic bandages have a stabilizing effect after injuries.


Knee injuries require consistent aftercare with a view to optimal regeneration. This is ensured by several groups of people. On the one hand, it is the doctor treating you, such as a sports medicine doctor or orthopedist, who coordinates the aftercare and may order another imaging procedure to be carried out by a radiologist.

On the other hand, it is the physiotherapist who reactivates the functionality of the joint and surrounding structures through his treatment. Thirdly, however, the cooperation of the patient is also required, who, for example, regularly carries out physiotherapy exercises at home or in the fitness studio and can thus ensure the success of the treatment.

Conservation is very important with regard to optimal regeneration. The length of time is decided by the physiotherapist and doctor, but it is the patient who must follow these instructions. Athletes in particular often have the tendency to want to get back into training and competitions too early. In order to avoid a relapse or a delayed regeneration, the prescribed physiotherapy exercises should be carried out.

These serve to strengthen the muscles surrounding the joint and also restore mobility in the knee joint as best as possible. If the knee joint injury is accompanied by a suture, protection is particularly important. Stability is an important factor when it comes to the knee joint. Appropriate splints must therefore be worn consistently as part of aftercare.

You can do that yourself

The relief of knee injuries can be accompanied by medical treatment in a number of ways. However, in order not to suffer permanent damage, it is essential to be examined and medically treated by a doctor.

During treatment, the knee should not be subjected to any or only minimal stress. If the state of health allows it, movement can be done carefully and slowly. Daily physical therapy exercises, performed in consultation with a therapist, aid in recovery. Wearing healthy shoes is mandatory. The use of shoes with high heels or in the wrong size should be avoided as a matter of principle. In order not to subject the knee or leg to unnecessary strain, closed, comfortable and breathable shoes are recommended.

In the case of a knee injury, compensating movements are often made, which lead to a bad posture of the body. The affected person should make sure in good time that the healthy body regions are not exposed to excessive or one-sided stress. Compensatory movements are necessary that aim to prevent muscle or bone damage. Everyday commitments must be restructured after a knee injury so that relief can take place. The help of people from the immediate vicinity should be resorted to. It is also important for those affected to pay attention to their emotional well-being.

Knee Injuries