Osteoarthritis of the knee: What do injections bring to the knee?

Osteoarthritis is the most common joint disease. In osteoarthritis, the cartilage layer of a joint is destroyed.

Pain, inflammation and restricted movement occur. If the knees are affected by osteoarthritis, doctors speak of gonarthrosis. In order to delay an operation, many sufferers hope for injections. But what good are injections in the knee?

In knee arthrosis (gonarthrosis), the protective cartilage in the knee joint breaks down. The protective sliding layer of the cartilage is damaged and the supply of nutrients to the joint is disrupted. Bone damage also occurs as the disease progresses. The knee loses mobility, loses its cushioning properties and has less support. Those affected notice the joint damage through pain, swelling and restricted movement. Unfortunately, joint wear cannot be reversed. But the pain can be relieved.

Cortisone injections to relieve pain in knee osteoarthritis

To relieve pain in knee osteoarthritis, those affected sometimes get cortisone injected into the knee joint. Cortisone is supposed to let the inflammatory processes subside and thus relieve the pain. Several international groups of scientists from Switzerland, Finland, the USA and Canada have evaluated existing studies on cortisone injections for knee osteoarthritis.

The result: cortisone injections were able to relieve the symptoms in 10 to 20 out of 100 people for up to eight weeks. However, cortisone injections carry the risk of infections and can weaken the articular cartilage if given repeatedly.

Cortisone shots: effective, but not harmless

“Cortisone is a potent painkiller, but should be used with great caution,” says Professor Philipp Lobenhoffer, specialist in surgery, special trauma surgery and specialist in orthopedics and trauma surgery at go:h joint surgery orthopedics in Hanover and member of the German Arthrosis Aid e.V.

“The risk of infection is increased with cortisone injections – not only during the injection itself, but also during subsequent, prompt surgical interventions. This is partly due to the fact that cortisone weakens the immune system in the joint and inhibits cartilage metabolism.”

Regular cortisone injections in the knee can even reduce cartilage mass. The expert therefore advises using cortisone injections in individual cases and not for long-term therapy. The German Society for Orthopedics and Orthopedic Surgery also advises using cortisone injections for the short-term treatment of acute knee pain – if other treatments are not sufficient. Some experts also recommend taking a break of at least twelve weeks between the individual injections.

How effective are hyaluron injections for knee osteoarthritis?

Only cortisone injections have been proven to temporarily alleviate osteoarthritis of the knee. The situation is different with hyaluron injections, which can also be injected into the knee. Although hyaluronic acid is the main component of natural synovial fluid, there is no scientific evidence that hyaluronic acid can rebuild the cartilage in the knee. Studies also failed to demonstrate a clear benefit over placebo injections.

The medical service of the central association Bund der

Krankenkassen e.V. (MDS) evaluates hyaluronic acid injections in knee arthrosis as “tends to be negative”. The weighing of benefits and harms is complex: Compared to placebo injections (injections of a dummy drug) and no injections, it has been shown that pain can be reduced somewhat with hyaluronic acid and the function of the joint improves slightly.

At the same time, reactions at the injection site would occur more frequently after a hyaluronic acid injection. In addition, there were “serious adverse events” that occurred statistically more frequently than in the control groups. This can temporarily lead to pain, redness and swelling in the joint.

Autologous blood therapy and stem cell therapy for knee arthrosis

Conclusive studies are also lacking for newer procedures such as autologous blood treatment or the injection of stem cells into the knee. So far, it has not been possible to prove that these osteoarthritis therapies have any benefit.

The German Society for Orthopedics and Orthopedic Surgery does not currently recommend injections with autologous blood. Other professional societies even advise against it. Injections with the body’s own stem cells are also not recommended by the specialist societies.

Movement therapy shows better effects

As the studies by the researchers from Switzerland, Finland, the USA and Canada show, exercise therapy is a possible alternative to injections. The evaluation of various study results showed that cortisone injections are of no benefit if exercise therapy is carried out at the same time and that physiotherapy with guided exercises for the home helps better in the long term.

With this, the scientists are showing what doctors have repeatedly emphasized: Strengthening and movement exercises are among the most important measures that those affected by knee osteoarthritis can take for their knees.

Movement stimulates blood flow and metabolism in the joint, thereby supplying the joint with important nutrients. The best way for those affected to discuss what type of movement and what intensity is most suitable for the respective stage of osteoarthritis is with their treating orthopaedist or orthopaedist.