What is a steroid/cortisone injection?
Corticosteroid (cortisone) is a well-established anti-inflammatory medicine routinely used to manage osteoarthritis (wear and tear changes to the joint), including the knee. Corticosteroid is the most common injection given for knee arthritis. It has a strong anti-inflammatory effect and is usually very effective in reducing the pain, swelling and inflammation associated with osteoarthritis. This type of injection is referred to as "an intra-articular steroid injection". They are also used to treat other inflammatory conditions like bursitis (inflammation of sac-like fluid collections present in different parts of the body) and tendonitis (tendon inflammation). Steroid injections do not just mask or hide the pain. Instead, they act by reducing the inflammation in the targeted area, thus providing a strong and local anti-inflammatory effect to help control the symptoms and allow the patient to manage the condition, usually by undergoing a physiotherapy rehabilitation program.
Triamcinolone (Kenalog) and methylprednisolone (Depo-medrone) are commonly used steroid injections for musculoskeletal conditions. These preparations are long-acting steroid injections which can take a few days to start working. Current evidence suggests that cortisone can improve pain and function for up to 3 months, but in some cases, it can last longer. The injections usually also contain a local anaesthetic that provides immediate pain relief lasting a few hours.
What is the benefit of having an ultrasound-guided injection vs a non-guided one?
Ultrasound is beneficial to assess the joints, tendons and ligaments for any suspected injury or inflammation. In addition, it allows for direct visualisation of the needle to ensure the steroid medication is injected into the same targeted site. There is significant evidence that ultrasound-guided injections provide better pain relief and more prolonged effects than injections without imaging guidance. This is because ultrasound guidance allows for accurate placement of the needle and, thus, delivery of the medicine to the exact site of pathology. In addition, injecting under ultrasound guidance helps visualise the adjacent structures and reduces the risk of tissue injury at the injection site.
What are the possible side effects of a steroid injection?
Most people have intra articular steroid injections without any significant side effects. However, possible side effects from an intra articular steroid injection include:
Pain and discomfort for a few days, often referred to as a "steroid flare". Simple painkillers like paracetamol can help with this.
Temporary bruising due to small blood collection under the skin at the injection site.
"Infection" is rare but essential for our patients to be aware of. Studies suggest this occurs in less than 1 in 10000 cases. The symptoms of infection are pain, swelling and redness at the injection site. Sometimes patients may develop a fever. Get medical advice as soon as possible if you have these symptoms.
Injury to structures close to the injection site. This is rare with ultrasound guidance.
Local thinning of the fat at the injection site. Although this is uncommon, it can happen when injecting structures very close to the skin. It can cause dimples in the skin and can be permanent.
Local change in colour (usually lightening) of the skin at the injection site. Discolouration is harmless but can be permanent.
If you have diabetes, your blood sugar level may temporarily increase.
If you regularly suffer high blood pressure, your blood pressure may temporarily increase.
Temporary facial flushing.
Other side effects like mood changes, increased appetite, difficulty in sleeping and menstrual disturbance are very rare with intra articular injections and more associated when the steroids are consumed as tablets, injected into the muscle (intra-muscular) or the blood (intravenous).
What are the knee conditions that a cortisone injection can manage?
An ultrasound-guided knee joint steroid injection can be helpful for the management of a good number of knee problems. These include:
What to expect during an ultrasound-guided injection appointment?
A specialist doctor (musculoskeletal radiologist) will ask you questions and perform the ultrasound examination. Then the doctor will explain the procedure to you. The injection site must be exposed so we can sterilise the area (cleaned). Wearing comfortable clothing that allows the injected body part to be exposed easily will be helpful. Then the doctor will use the ultrasound machine to guide the needle into the exact preferred site and inject a mixture of steroid and local anaesthetic (numbing medication). A small plaster is applied to the injection site when the injection is complete. You can remove this later during the same day. You can eat and drink before and after a steroid injection. You can shower as usual but avoid very hot showers/steam rooms. You can use painkillers like paracetamol if you experience pain at the injection site. It's advised not to drive immediately after the injection as it usually contains a small amount of local anaesthetic (numbing medication). It is also advisable to avoid extraneous exercises for 48 hours after the injection. Instead, rest the area for 48 hours after the injection.
How many steroid injections can I have?
Discussing this with your doctor during the consultation would be best, as repeated steroid injections can increase the risk of side effects. There is also concern that repeated intra articular steroid injections might cause damage to the cartilage (in case of intra articular steroid injections). Therefore, steroid injections are usually performed at most 3-4 times a year into the same body part.
What are other alternative injections for knee pain?
Mainly, three injection options are available to help manage knee osteoarthritis.
Can I have both cortisone and hyaluronic acid injections for knee pain?
The answer is Yes, and there is some evidence supporting having both injections. You can have both injections at the same appointment or separate them by a few weeks (we refer to this as staged injections). We recommend the second option. Having the cortisone injection first will produce an immediate anti-inflammatory effect. Then you can have the Hyaluronic acid injection approx. four weeks later to provide a longer-lasting result. Having both injections together will make it difficult to assess the response to an individual injection. In addition, some studies suggested that adding cortisone to hyaluronic acid can reduce the effect of the hyaluronic acid component. You can find out more about hyaluronic acid injections here.