Pain after knee surgery

Definition

Operations on the knee joint are very common. In Germany, approximately 175,000 new knee joints are inserted each year. However, even if no knee prosthesis is fitted, the knee is a joint that is frequently operated on, as injuries to the menisci or surrounding ligaments are easy to cause, especially in sports such as skiing or soccer.

The procedures performed are generally very safe procedures that are performed frequently. Nevertheless, it can never be ruled out that a complication may occur during an operation that leads to pain. This can include post-operative bleeding, infection or injury to nerves. More information on this topic under: Postoperative complications

Causes

In general, knee pain in the phase immediately following knee surgery is nothing unusual or worrying. Pain is part of every wound healing and is based on the fact that body structures are inevitably injured during every operation. However, if the pain is unusually severe or prolonged, accompanied by fever and excessive swelling or other symptoms, an unplanned complication has probably occurred.

This may be post-bleeding, which can develop into a strong, painful bruise in the knee. In addition, there may also be an infection with inflammation of the joint. Furthermore, there may also be wound healing disorders or nerves may have been injured or irritated.

Wound pain refers to pain that occurs in the area of a wound. The pain does not only exist directly after the injury, but also during the healing process and in rare cases it remains even after healing. An operation on the knee joint can also be a trigger for wound pain.

In general, the pain increases with the size of the wound. Therefore, wound pain is generally less after minimally invasive measures than after open surgery with a lot of tissue injury. To relieve wound pain, infection of the wound should be prevented at all costs.

In addition, anti-inflammatory painkillers and cooling procedures help to relieve pain. The acute wound pain after knee surgery should already decrease within a few days. If the knee is painfully swollen after surgery and is also reddened and overheated, these are signs of infection.

This means that either germs have entered the knee joint during the operation or that the body has become susceptible to already existing germs due to the slight weakening of the immune system after the operation. The colonization of the knee joint with germs triggers an inflammatory reaction and can cause lasting damage to the joint. In advanced stages of the infection, fever can also occur.

Once a bacterial infection has been diagnosed, treatment with antibiotics should be initiated as soon as possible. Depending on the source, the rate of infection after insertion of a knee prosthesis is between 0.3% and 5%. More information on this topic under: Surgery of a knee prosthesisA nerve can be damaged during an operation either by a complete or partial severing of the nerve or by sustained pressure or tension.

In addition, nerve damage can still occur after the operation, for example, if a severe bruise develops that pinches the nerve. The nerve damage can be manifested either by lost sensation in the area of the knee or lower leg or by muscle weakness below the knee and a reduced Achilles tendon reflex. Further information on this topic at: Nerve damageA small amount of blood is lost during every knee operation.

However, if there is still bleeding after the operation and after removal of the drains, the blood collects in the cavity of the knee joint. Since the tissue there can only expand to a limited extent, a painful swelling occurs. Such a bloody joint effusion is also called haemarthros.

In addition, the joint may be restricted in its mobility due to the bruise. Small amounts of blood can easily be broken down by the body within several days. However, if the effusion is too large, it can be relieved by the orthopedic surgeon by means of a thin hollow needle in the course of a joint puncture.

Blood vessels can also be damaged during an operation. If these are large vessels, the damage is repaired directly during the operation and the vessel is repaired. Minor vascular injuries do not usually lead to permanent circulatory disorders, as several small blood vessels can usually supply a region of the body with blood and compensate for the failure of a vessel.However, in rare cases during surgery, small fat droplets may be transferred from the fatty tissue of the surrounding tissue into the blood system.

These can occlude blood vessels and thus lead to arterial thrombosis with subsequent reduced supply to the affected body part. Thrombosis is one of the most dreaded complications after operations in general, especially after operations on the legs and feet. It is a blood clot (= thrombus) that forms in a vein (a vessel that transports blood to the heart).

Especially in the leg veins, movement plays an important role in blood transport. By activating the muscles, for example in the calf, the blood is also pumped upwards towards the heart. If this activity is missing, for example because someone is not allowed to perform after knee surgery, the blood moves more slowly and disorderly through the vein.

This greatly increases the risk of thrombus formation. If a thrombosis occurs, the affected leg swells below the blood clot, often overheating, the skin tightens and the leg may hurt. The greatest risk is that the thrombus comes loose and reaches the lungs through larger veins. There it can clog such large vessels that life-threatening breathing difficulties can result.