Getting a knee injection is not very different from getting any other injection (e.g. a vaccination)
A dog’s bark being worse than his bite, and all that- you’ll probably feel worse in your surgeon’s waiting room than while the needle is actually in your knee.
The special thing about a knee injection is that everything needs to be sterile (super clean) because your surgeon will introduce a (small) needle directly into the joint. Our bodies naturally keep our joints germ free, and the needle opens a (microscopic) tunnel through which bacteria can invade and have a party inside your knee.
No matter how much you may like parties, this is not a good thing, so every care will be taken to ensure the injection process is cleanly carried out.
Most knee injections for osteoarthritis are done in the surgeon’s clinic, and you can go home almost immediately after the injection. In some cases, your surgeon may advise you to have it done in the operating room.
This allows the surgeon to check your knee under an x-ray during the injection or perform a manipulation (some therapeutic movements) of your knee at the same time.
A. Before:
In all cases, you will be asked to fill out a consent form where you indicate that you understand why you need to have the injection, its benefits and possible risks. This is a legal document used in nearly all medical procedures and you should always ask your surgeon any questions you need to about the injection before you sign your name on the page.
Next -if the injection is going to be done in your surgeon’s clinic – you will be seated back comfortably on an examination table while the surgeon prepares your knee for the injection.
If you choose to wear long pants/trousers that day, they should be loose enough for you to roll the pant legs up to the middle of your thigh or higher.
Surgeons use various different antiseptics to clean the knee before injecting, which can depend on your allergies and sensitivities.
Your surgeon will determine the best one for you, but I usually advise my patients to wear black or dark coloured pants (or a black or dark skirt or dress), just in case any of the disinfectant chemicals I use to clean their knee causes a stain on the fabric.
B. During:
Once your knee is cleaned and ready, your surgeon will use a small needle to prick through your skin and enter your knee joint. Once the needle is within the knee joint, you may see a small amount of yellowish sticky fluid flow out through the needle.
Sometimes this may be mixed with a little bit of blood – this is normal, so don’t worry. If you think seeing this might make you uncomfortable, you might want to lie back, relax and close your eyes. I find it helpful to ask my patients to imagine they are somewhere they enjoyed going on holiday (while the injection is being given).
The knee is a closed space – something like a room with soft stretchable walls – so whether your surgeon gives the injection from the outer (lateral), inner (medial), or perhaps another part of your knee, the injected liquid (perhaps Hyaluronic Acid, PRP or Growth Factors/PRGF) will flow around inside the joint and touch nearly all its parts.
Your surgeon will decide which side to inject from depending on the type of injection you are getting, the part of your knee that is the most damaged.
If you have a skin condition that affects the skin around your knee, it may be best to treat this first before having an knee injection. Either way, being honest with your surgeon about your medical history will help ensure treatment is effective and safe.
At this point you might be wondering… “Where’s the Local Anaesthetic?!”
That’s a type of medicine that helps numb the pain during the injection. Most of my patients are very concerned about it – and I don’t blame them. I don’t enjoy getting poked with a needle myself.
Many surgeons inject a small amount of local anesthetic medicine into the skin just before giving the injection, and others (myself included) use a ‘numbing’ spray to temporarily reduce the pain of the injection.
But really, even if no local anesthetic is given, the pain of a knee injection is not that much more than the pain you feel when you have blood taken for a blood test. Your surgeon may prescribe some medicine for a few days after to reduce pain and swelling.
C. After
Once the injection is over, the surgeon will clean the injection site, and – if necessary, apply a small plaster to protect the wound. You can usually stand up and walk a few minutes after the injection. Your surgeon will tell you when you can safely remove the plaster, and if there are any precautions you should take (e.g. not to wet your knee while bathing). In most cases, you can take a shower and wet your knee the day after the injection.
As we saw earlier, one dangerous possible complication is a knee infection (septic arthritis). It is very rare, but it’s important to remember that you should see your surgeon immediately if you have a unbearable knee pain, knee swelling or fever in the week after your knee injection.
Depending on the kind of injection you have, it may be a few days after the injection before you start to feel the beneficial effects. In some cases, your surgeon might advise you to wear a knee brace after the injection to reduce the stress on your knees.
But in all cases, the whole idea of getting a knee injection is to get you moving and improve your quality of life.
So go out into the world and live your life.
Originally written on 15 August 2020 in Quill Orthopaedic Specialist Centre, TTDI, Kuala Lumpur.
