Knee Joint Injections

What is a knee joint?
Knee joints are formed by the connection between the femur and tibia bones. Pain from these joints can be caused by injury or inflammation. If these joints are blocked or anesthetized (i.e. numbed), they will not be able to transfer the painful sensation to the brain. Knee injections are performed with diagnostic and therapeutic intent, meaning that it helps to diagnose whether the knee joint is the source of pain and to also treat the pain.

How is the procedure performed?
The patient lies on his/her back or sits upright at the edge of the exam table. The skin of the knee is cleansed with antiseptic solution and a sterile field is created. Under X-ray (fluoroscopy), ultrasound, or landmark guidance, a small needle is advanced into the targeted knee joint. A small amount of contrast dye may be injected to ensure accurate needle placement. Typically, a combination of local anesthetic and steroid is injected. However, at times other therapeutic agents such as platelet-rich plasma (PRP) is used instead. The injection takes about 5 minutes to complete.

How long does the effect last?
Pain relief in the first couple of hours after the injection is the most important as this tells us if our diagnosis of pain coming from the knee joint is correct. Pain relief from the local anesthetic typically only lasts a few hours. Pain relief from the steroid takes around 3-10 days to take effect and may last weeks to months.

What is the next step after the injection?
Following the injection, you will be free to get re-dressed and check out at the front desk. You will have a follow-up appointment in about 6 weeks.

What are the risks and side effects?
Serious side effects and complications are rare. The most common problem after the injection is having slightly increased pain in the area of the injection for up to a few days. The other potential complications are infection, bleeding, and nerve injury. These complications are minimized by using sterile technique and imaging guidance. Some individuals may temporarily develop headaches, facial flushing, higher than normal blood pressure, and high blood sugar from the steroid, all of which typically resolve within a few days.