Intracapsular Hip Block
What is an Intracapsular Hip Block?
The hip joint lies deep in the groin, considerably closer to the midline than many people imagine (it lies almost directly behind the pulse that you may be able to feel in your groin). This makes it difficult and unreliable to inject by touch, but using an X Ray machine an injection into the joint is normally straightforward, or the injection can also sometimes be guided by ultrasound. The hip joint is surrounded by a capsule which contains the joint ("synovial") fluid and the injection is placed into this fluid.
We often do an intracapsular hip block either to try to relieve joint pain (particularly in people who are too unwell for hip surgery or in whom the surgery is inappropriate) or as a diagnostic procedure to assess whether pain is coming from the hip joint.
Where is the injection carried out?
You will be asked to attend the Day Surgery Unit for half a day (morning or afternoon) On the day you will be greeted by a nurse who will look after you until you go home. You may be asked to change into a gown and will be taken to one of the operating theatres for the procedure.
How is the injection done?
You will be asked to lie on your back on a special table that allows us to use an X Ray machine to guide the injections. The dose of XRays used is tiny: the machine intensifies a very small XRay dose in a similar way to army night vision goggles. X-ray pictures are taken throughout to ensure the needle is in the correct area.
The skin overlying the joint marked and then sterilised with a cold solution and a small amount of local anaesthetic is injected with a tiny needle to numb the skin. Following this a fine needle is placed either into the joint. Once the needle is in the correct position a small amount of X Ray dye ("contrast") is injected to outline the joint and confirm the position.
A small volume of local anaesthetic and steroid is then injected into the joint.
The steroid acts only around the area it is injected into and does not have the same effects as taking long-term steroids.
Does it hurt?
You do not need a general anaesthetic for this procedure. Sometimes, on contacting the joint, there can be some temporary discomfort - because the most painful part of the joint is ofen the interior of the capsule it is not possible to fully numb this befoe passing the needle into the joint. However, this is normally very minor and the doctor will ensure pain is kept to a minimum by using local anaesthetic. Once the procedure is over you may have some tenderness over the injection site but no worse than after any other type of injection.
How long will it all take?
Although the procedure itself usually only takes 10-15 minutes you will be asked to stay for up to an hour or so after the injection in the Day Surgery Unit before going home, and we will need to ensure that you have no weakness of the thigh afterwards. In the very rare case of this happening we will need to ask you to stay until it wears off, for your safety.
You may move around freely at home unless you have been advised to the contrary by a member of staff. Indeed, the patients who do best after this procedure are normally those who make use of the pain relief from the procedure to increase the amount of activity and exercise they do. You do not need to do any specific back exercises unless you have been instructed to do so.
- You may have mild discomfort at the site of the injection; this should last no longer than 48 hours. In a number of patients it can make your symptoms worse for about a week.
- Extremely rarely you may get a numb leg which lasts for a few hours. This is because the femoral nerve, which supplies the thigh, is situated just in front of the hip joint and local anaesthetic could spread to this. There is an extremely tiny risk of some damage to the nerve from the needle.
- As for any procedure, we have to warn you that there are very small chances of rare complications such as infection.
- If you have diabetes your blood sugar level can temporarily become less well controlled.
- Very rarely people can be allergic to the injection, which results in redness and itching. This is not serious, but we need to know for future treatments. Very occasionally you may feel some flushing sensations for the first day or two after the injection, as a normal side effect of the steroid.
- Serious complications with this procedure are extremely rare, but if problems arise please consult the Pain Clinic Office, or your own doctor who will contact the Pain Clinic if necessary.
(Please see general comments on the Procedures page)
You can download our Pain Service's information sheet on Intracapsular Hip Block from this link.
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Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 22/6/2016