A joint injection is a procedure where medication is delivered directly into a joint space using a needle, either to relieve pain or to help diagnose the source of that pain. The most common targets are the knees, shoulders, hips, elbows, ankles, and wrists. Because the medication goes straight to the problem area rather than traveling through your entire bloodstream, joint injections can provide faster, more concentrated relief than oral painkillers.
Therapeutic vs. Diagnostic Injections
Most joint injections fall into one of two categories. Therapeutic injections deliver medication meant to reduce pain and inflammation. Diagnostic injections use a numbing agent to confirm where your pain is actually coming from.
In a diagnostic injection, a local anesthetic is placed into a specific joint under imaging guidance. You’re asked to rate your pain beforehand, then perform the movements that normally trigger it. If the numbing agent eliminates at least 75% of your pain, that joint is likely the source. Doctors sometimes repeat this test with a different anesthetic to confirm the result, a process called a double block. This approach is especially useful for joints like the sacroiliac joint in the lower back, where pain patterns overlap with other conditions and physical exams alone can’t always pinpoint the cause.
Types of Therapeutic Injections
Corticosteroid Injections
Cortisone shots are the most widely used joint injection and typically the first option offered. They work by reducing inflammation directly inside the joint, which in turn lowers pain. A meta-analysis of randomized controlled trials found that corticosteroid injections provide mild to moderate pain relief for up to three months in knee osteoarthritis, with the benefit fading around the four-month mark. That’s longer than many people expect, though relief varies from person to person. Some people get months of meaningful improvement; others notice the effect wearing off sooner.
Hyaluronic Acid (Gel) Injections
Your joints naturally contain a thick, slippery fluid called synovial fluid that cushions cartilage and reduces friction during movement. In osteoarthritis, this fluid thins out and loses its shock-absorbing properties. Hyaluronic acid injections, sometimes called gel injections or viscosupplementation, aim to restore that cushioning. The injected gel mimics the structure of healthy joint fluid and acts as both a lubricant and a shock absorber. These are used most often in the knee when corticosteroid shots haven’t provided enough relief or when someone wants to avoid repeated steroid use.
PRP and Cell-Based Injections
Platelet-rich plasma (PRP) is the most studied option in a newer category called orthobiologics. The process involves drawing your blood, spinning it in a centrifuge to concentrate the platelets to three to five times their normal level, and injecting that concentrated solution into the joint. Platelets release growth factors that promote tissue repair, which is why PRP is thought to support healing rather than just masking symptoms.
A more advanced option is bone marrow aspirate concentrate, which contains stem cells capable of developing into cartilage, bone, or muscle tissue. However, these stem cells make up a tiny fraction of the sample, roughly 1 cell per 10,000. Bone marrow aspirate also contains higher levels of certain anti-inflammatory compounds than PRP does. While both approaches have shown promising results, PRP has a much longer track record in clinical research, and bone marrow-based injections are still relatively new in comparison.
What Happens During the Procedure
Before the injection, your doctor will review your medical history, checking for allergies, infections, and conditions like diabetes that could affect how your body responds. You’ll be positioned to expose the joint being treated. The skin over the injection site is thoroughly disinfected, and the area may be numbed with a local anesthetic spray or small injection.
Many providers use ultrasound to guide the needle in real time. This allows them to watch the needle’s path on a screen and place it precisely within the joint space. Ultrasound guidance is harmless, repeatable, and doesn’t involve radiation, making it practical for use in a standard office visit. For deeper or harder-to-reach joints, fluoroscopy (a type of live X-ray) or CT guidance may be used instead. The injection itself typically takes only a few minutes. The needle passes through the skin, underlying tissue, and sometimes ligaments before reaching the joint cavity, where the medication is released.
Recovery and Activity After an Injection
The first 24 hours after a joint injection should consist of relative rest. This allows the medication to absorb properly and gives your provider a window to catch any adverse reactions. For injections in the hip, knee, ankle, or other weight-bearing joints, you can begin light activity like stationary cycling or bodyweight exercises 24 to 48 hours after the procedure, gradually increasing intensity.
The general recommendation is one to two days of rest for the affected area, followed by a progressive return to normal activity. This timeline applies whether you’re an athlete or someone returning to daily routines. Resting the joint briefly may also help maximize the injection’s benefit and reduce the chance of systemic side effects from the medication spreading beyond the joint.
Risks and Contraindications
Joint injections are low-risk procedures overall. The most serious potential complication is a joint infection, called septic arthritis. A large retrospective study found the absolute risk to be about 18 cases per 10,000 injections within 21 days of a corticosteroid injection into a large joint. That translates to roughly a 0.18% chance. Some people experience a temporary flare of pain in the first day or two after a steroid injection, which typically resolves on its own.
Certain situations rule out a corticosteroid injection entirely. If there’s an active skin infection at the injection site, an existing joint infection, a fracture in the area, or a prosthetic joint, the procedure should not be performed. People taking certain antiviral medications need special coordination between their doctors before receiving a steroid injection, because drug interactions can amplify the steroid’s effects throughout the body.
How Long Results Last
Duration of relief depends heavily on the type of injection and the severity of your condition. Corticosteroid injections in the knee typically provide meaningful pain reduction for up to three months, with diminishing returns after that. Hyaluronic acid injections may last longer for some people, particularly those with mild to moderate osteoarthritis, though individual responses vary widely. PRP injections are thought to work more gradually since they promote tissue repair rather than simply reducing inflammation, so the timeline for noticing improvement can stretch over several weeks.
Repeat injections are common, but there are practical limits. Repeated corticosteroid injections into the same joint can weaken cartilage and surrounding tissues over time, so most providers space them out and limit the total number per year. Hyaluronic acid and PRP injections don’t carry the same tissue-weakening concern, which is one reason they’re sometimes preferred for longer-term management.