Knee replacement is a standard operation for knee arthritis. Around 80% of people report good results, but 15–20% have ongoing pain afterwards. We use cortisone injections to treat pain and inflammation from arthritis — so can you have one after a knee replacement, and what are the risks?
What is cortisone?
Cortisone is a powerful anti-inflammatory. Injected into a joint, it reduces inflammation and eases pain, which makes it useful for arthritis, bursitis, and tendonitis. But it also suppresses the immune system — and that matters a great deal around a joint replacement.
Steroid injections after knee replacement: the infection risk
Cortisone doesn’t only reduce inflammation. It also suppresses the immune system and impairs tissue healing — and we think both effects make an artificial joint more vulnerable to infection.
Injecting cortisone into a knee replacement can also introduce bacteria directly into the joint. Combined with cortisone’s effect on the immune system, that raises the risk of a prosthetic joint infection — a serious complication that often needs prolonged antibiotics and further surgery.
A review of all the evidence on cortisone injection into a knee replacement found that:
- It’s a high-risk procedure
- The risk of infection increases by over 50%
- We don’t actually know how effective the injection is
For these reasons, we strongly advise against injecting cortisone into a knee replacement.
Can you inject cortisone around a joint replacement?
Yes — and this is an important distinction. Sometimes pain after a knee replacement comes from the prosthesis irritating soft tissue outside the joint: fat pad impingement, iliotibial band inflammation, or a trapped nerve.
In these cases, a targeted cortisone injection into the soft tissue — not the joint — can help. It must be done under ultrasound guidance, both to place it accurately and to avoid accidentally entering the joint itself. This is precisely where accurate, ultrasound-guided placement matters most.
If you have pain after a knee replacement, see your surgeon first, to rule out causes such as loosening, malpositioning, infection, a fracture, or a metal allergy.
What are the other options for pain after a knee replacement?
Physiotherapy to improve knee strength and mobility settles most cases of soft-tissue impingement. Other options include medications for chronic pain, such as amitriptyline or duloxetine.
Frequently asked questions about cortisone after a knee replacement
Can I have a cortisone injection somewhere else while I have a knee replacement?
Yes. A cortisone injection elsewhere — for example in the shoulder — is fine, as long as it isn’t into the replaced knee joint itself. The concern is specifically about injecting into or around the prosthesis, not about having cortisone elsewhere in the body.
Does a cortisone shot before a knee replacement increase the risk of infection?
Yes. A systematic review of over 300,000 knee replacements — nearly half of whom had a cortisone injection beforehand — found that a cortisone injection before the operation raises the risk of infection afterwards. The risk is highest within six weeks of surgery, and remains raised within three months. For the full picture on timing, see how soon after a cortisone shot you can have surgery.
Can you inject cortisone around a hip replacement?
As with a knee, we avoid injecting into a hip replacement. But persistent hip pain can come from the hip flexor tendon catching against the prosthesis cup — and a targeted cortisone injection around the hip flexor tendon can help in that situation.
My surgeon gave me a steroid injection after a knee replacement, and it helped — is that wrong?
Not necessarily. A surgeon may use a carefully considered injection around the soft tissues in specific circumstances, weighing the risks for that individual. The strong general advice against injecting is about the joint itself. Always follow the advice of the surgeon who knows your case.
What should I do if I have pain after a knee replacement?
See your surgeon first. Pain after a replacement needs assessment to exclude serious causes — infection, loosening, malpositioning, fracture, or metal allergy — before considering treatments such as physiotherapy, pain medication, or a targeted soft-tissue injection.
Final word from Sport Doctor London about steroid injection after knee replacement
A cortisone injection into a knee replacement is a high-risk procedure and should be avoided, because of the risk of infecting the prosthesis. A targeted injection around the joint, for soft-tissue impingement, is sometimes appropriate under ultrasound. If you have pain after a knee replacement, see your surgeon first to exclude a serious cause such as infection or loosening.
If you have soft-tissue pain around a joint replacement and would like an assessment, Dr Masci can see you in London, including ultrasound in clinic. Contact the team here or call +44 (0) 203 488 0350.
4 weeks after knee replacement
.Can I have a cortisone injection in my shoulder?
yes cortisone injection is allowed as long as you don’t have it in the knee joint.
LM
I recently (9/9/25) had a second full knee replacement, I had a great team on my recovery from day 1. From procedure to physical therepy. My results on range and pain levels were very good about week 9 everything went wrong from reduced range to moderate pain. Made it difficult getting around and very difficult getting sleep. I received a low dose cortisone from my surgeon and it increased my pain temporarily 3hrs max to reducing my pain at least by 60% with in 6hrs. By morning my pain was maybe a level 2 and I was able to get a better sleep on the first night. Doctor ordered an inflammation for 6 days. I go back in 6 weeks for follow up. To me just in the short time it has been 100% improvement on my continuing recovery.