Knee injection is a treatment method used to address issues such as pain, inflammation, or restricted movement in the knee joint. This therapy involves injecting medications or biological substances directly into the joint and is typically preferred as a non-surgical solution. Today, intra-articular knee injections include innovative treatments such as hyaluronic acid, corticosteroids, PRP (platelet-rich plasma), stem cells, and exosomes. In this article, we will focus particularly on intra-articular stem cell and exosome applications, providing a comprehensive guide on knee injections.
What is Knee Injection?
Knee injection is the process of administering various substances into the knee joint via a needle. The goal is to reduce inflammation, manage pain, and improve joint function. Intra-articular fluid injections are commonly used for conditions like osteoarthritis (joint calcification), rheumatoid arthritis, or sports injuries. While traditional methods primarily involve corticosteroids and hyaluronic acid, intra-articular stem cell and exosome applications have gained popularity in recent years as regenerative (restorative) treatments.
When is Knee Injection Preferred?
Knee injections may be preferred in the following cases:
- Chronic knee pain (especially due to osteoarthritis),
- Reduced joint fluid or cartilage wear,
- Inflammatory joint diseases (e.g., rheumatoid arthritis),
- Insufficient results from physical therapy or oral medications,
- Support for recovery after meniscus tears or ligament injuries.
Intra-articular joint injections are an effective alternative, particularly for patients who wish to avoid surgery or are not suitable candidates for it. However, innovative methods like stem cell and exosome therapies not only alleviate pain but also target tissue repair.
How is Knee Injection Performed?
Knee injection is performed in a sterile environment, typically under local anesthesia. The procedure includes the following steps:
- The knee area is cleaned with an antiseptic solution.
- Local anesthesia is applied to ensure patient comfort.
- The medication or biological substance is injected into the joint, guided by ultrasound or direct needle placement.
- The injection site is bandaged, and the patient is discharged after a brief rest period.
For intra-articular stem cell applications, stem cells are harvested from the patient’s bone marrow or adipose tissue, processed, and injected into the knee joint. Exosome applications involve injecting laboratory-prepared exosomes (nano-sized vesicles secreted by cells) into the joint. Both procedures take approximately 10-20 minutes.
How Many Times Can Knee Injections Be Performed?
The frequency of injections depends on the substance used and the patient’s condition. Corticosteroids can be administered every 3-6 months, while hyaluronic acid is typically given in a series of 3-5 sessions. Intra-articular stem cell applications are usually performed in a single session but may be repeated after 1-2 years based on effectiveness. Exosome applications are planned as 1-3 sessions, depending on the case.
Who is Eligible for Knee Injections?
Knee injections are suitable for:
- Individuals with chronic knee pain (especially those over 40),
- Patients with cartilage damage or joint fluid loss,
- Those recovering from sports injuries,
- Individuals seeking to avoid surgery.
However, patients with active infections, bleeding disorders, or pregnancy should avoid this treatment. Intra-articular stem cell applications are ideal for early-to-moderate osteoarthritis, while exosome applications are preferred in a broader range of cases requiring tissue regeneration.
Why Are Knee Injections Performed?
Knee injections are performed to reduce pain, control inflammation, and improve joint mobility. Knee fluid injections restore joint lubrication, while stem cell and exosome therapies offer regenerative effects.
Pain Management and Joint Function Support
Pain management and joint function support are primary goals of knee injections. Hyaluronic acid enhances joint lubrication, while corticosteroids suppress inflammation. Intra-articular stem cell applications promote the repair of damaged cartilage and tissues. Stem cells, sourced from the patient’s body (typically adipose tissue or bone marrow), support joint regeneration. Exosome applications contain bioactive molecules secreted by stem cells, reducing inflammation and accelerating tissue repair.
What Should Be Considered After Knee Injection?
After knee injection, patients should:
- Avoid overstraining the knee for the first 48 hours (e.g., running, heavy lifting).
- Contact a doctor if redness or swelling is noticed at the injection site.
- Drink plenty of water and rest to support recovery.
- Seek immediate medical attention for severe pain or fever post-injection.
For stem cell and exosome applications, recovery may take weeks, requiring patience.
Are There Possible Side Effects of Knee Injections?
Knee injection side effects are generally mild and temporary, but risks vary by method.
Most Common Knee Injection Side Effects
- Pain, swelling, or bruising at the injection site,
- Temporary restricted movement,
- Rare infection risk,
- Elevated blood sugar with corticosteroids,
- Minimal allergic reactions with stem cell or exosome applications.
Intra-articular stem cell and exosome applications, derived from the patient’s tissues, are generally safe, but infection risk increases if sterile conditions are not maintained.
What Are the Differences Between Knee Injection and Physical Therapy?
Knee injections and physical therapy are distinct approaches to treating knee pain. Knee injections provide rapid relief by directly targeting the joint. For example, intra-articular stem cell applications focus on tissue repair, while exosome applications reduce inflammation and support regeneration. Physical therapy, however, offers long-term improvement by strengthening muscles and enhancing joint stability. Typically, injections control acute pain, followed by physical therapy to reinforce treatment.
Details About Intra-Articular Stem Cell Applications
Intra-articular stem cell applications are a groundbreaking method in regenerative medicine. This treatment involves harvesting stem cells from the patient’s bone marrow (usually from the pelvic bone) or adipose tissue (e.g., abdominal area), concentrating them through specialized processing, and injecting them into the knee joint. Stem cells have the potential to repair damaged cartilage, meniscus, or ligaments. In early-to-moderate osteoarthritis, they promote cartilage regeneration, potentially delaying the need for prosthetic surgery.
The application process is as follows:
- Stem cells are collected under local anesthesia and processed in a centrifuge.
- The prepared solution is injected into the knee joint, guided by ultrasound.
- Improvement becomes noticeable over weeks to months.
The advantage is low side effect risk since the patient’s own cells are used. However, efficacy may be limited in advanced cartilage loss.
Details About Exosome Applications
Exosome applications are considered an extension of stem cell therapy. Exosomes are nano-sized vesicles secreted by cells, containing growth factors, proteins, and genetic material. When used in the knee joint, they reduce inflammation, promote cell regeneration, and accelerate tissue repair. Intra-articular exosome applications are typically performed with autologous (from the patient) or allogeneic (donor-derived) exosomes.
The application process is as follows:
- Exosomes are prepared in a laboratory (e.g., from the patient’s blood or donor stem cells).
- They are injected into the knee joint under sterile conditions.
- Effects begin within days, reducing inflammation, and continue with tissue healing over weeks.
Exosomes offer the advantage of requiring less invasive preparation than stem cells and provide rapid effects. Their low immunogenicity makes them suitable for a wide patient group.