INJECTION TECHNIQUES AND INDICATIONS
Injecting different parts of the body is common practice in orthopaedics, rheumatology, general practice and sports medicine. A good knowledge of this field is important. Its application not only helps confirm diagnoses but also treat certain conditions. This following discusses the most common reasons for injecting and will hopefully make you more confident in this field.
Local anaesthetic is useful to make certain diagnoses. It can be used alone or mixed with corticosteroid. Short acting agents include Lignocaine, whilst longer acting agents include Naropin and Marcaine. There are certain toxic doses but these are unlikely to be exceeded in general practice. If in doubt consult the product information sheet.
You can use adrenaline but always avoid its use on extremities (ie. digits) as it can cause vasoconstriction and gangrene.
It is important to remember if you stick a needle into something you think might be infected, send a specimen away.
Corticosteroid injections are used to relieve symptoms of arthritis in certain joints and are also used to reduce soft tissue inflammation. The appropriate use and knowledge of where and when to inject is extremely important. Inappropriate use can cause severe damage.
INDICATIONS FOR LOCAL ANAESTHETIC ALONE
- Suturing a wound
- Diagnosis of pain coming from a certain part of the body (e.g.an injection of the talonavicular joint in the foot or in the hip joint, to differentiate from back pain)
WHAT ARE CORTISTEROIDS?
Corticosteroids are an anti-inflammatory medication which can be injected into a joint or around tendons. Corticosteroid is usually mixed with local anaesthetic to reduce pain which is usually only quite mild.
WHEN IS IT USED?
There are multiple indications. We will discuss the most common ones. In general, it is used to relieve inflammation of tendons or joint inflammation. Intra-articular corticosteroids are primarily used for pain secondary to osteoarthritis but they can also be used in inflammatory conditions such as rheumatoid arthritis. They do not slow down or change the progression of arthritis.
They are generally used in patients with arthritic symptoms who are not symptomatic enough to warrant a total joint replacement. It is also used when trying to delay an inevitable joint replacement.
They are useful in patients who are not medically fit for surgery
HOW LONG DOES IT LAST?
The effects usually take 24 – 48 hours to work. For the first day or two, there can actually be a slight increase in pain as the corticosteroid starts to work. The effects can last anywhere from a week to 6 months but it is only temporary. You can repeat the injections if required (up to three a year).
WHERE IS IT DONE?
Corticosteroids can be injected into the joint in the office under aseptic conditions.
- Suspected infection in the joint
- Allergy to local anaesthetic or steroids
- Joint replacement
- Risk of infection (this is very low, about 1 in 5000)
- Skin discoloration
- Flare up of symptoms for a day or two
- Rise in sugar levels in diabetics
- Need to monitor levels carefully for two days
It is important to note that all side effects are low.
Corticosteroids can be injected into the knee in the office under aseptic conditions.
The choice of steroid varies. Dr Walker use 2 ampoules of Celestone mixed with 3 mls of local anaesthetic in a 5ml syringe. Mix using an aseptic technique and use a blue or green (21G, 23G) needle. The choice of injection portal is either superolateral under the patella with the knee extended or through the inferomedial or inferolateral soft part of the knee with the knee flexed to 90 degrees. Always use an aseptic technique.
The hip can be injected for a number of reasons. This needs to be done by a radiologist under image intensifier control. The most common reason is to help differentiate hip pain from back pain, as this can be confusing at times and patients can also have dual pathology. If the local anaesthetic helps significantly then it can be assumed that most pain is from the hip joint. Corticosteroid is usually injected at the same time for more prolonged symptomatic relief.
The other reason for injecting around the hip is trochanteric bursitis. This condition is relatively common and is quite a simple diagnosis to make. This region can be easily injected. The patient has symptoms located around the greater trochanter which are often worse after exercise and when lying on the affected side. It is often intermittent in nature. Clinically, the patient has localised tenderness around the greater trochanter. There can be some confusion if the patient has arthritis as well, but local tenderness to palpation is the giveaway sign.
Inject 2 ampoules of Celestone mixed with Lignocaine to make a total of 10 mls. The reason to Lignocaine is because it works within minutes, so before the patient leaves the office, they can tell you if it has worked and you have confirmed your diagnosis. Inject over the point of maximal tenderness and move the needle about a few times without withdrawing fully. Remember you want to get below the fascia lata but not as far as the bone, so depth depends on the size of the patient. This can be repeated 3 times if needed. The other therapeutic recommendations are anti-inflammatory medication and physiotherapy. Rarely is surgery required. Tests include an X-Ray, bone scan or MRI. Nothing beats an injection for diagnosis of this condition.
- Inject a joint replacement of any type
- Inject a tendon inserting directly onto a bone because it can cause rupture (e.g. achilles tendon, patella tendon)
- Inject through erythema or something which can cause a deep infection
- Keep injecting something without a clear diagnosis