Knee arthritis and cartilage wear has traditionally been considered an uncurable condition. In fact, the only consistently successful treatment whas a total knee replacement. Although knee replacements are a good option for severe arthritis, they require a large surgery, a prolonged recorvery course, and are usually associated with temporary, but significant, postoperative pain. Fortunately, advances in medical knowledge and technology have produced some very promising non-surgical treatments for knee arthritis. While there may not be a cure for arthritis yet, many of these treatments have shown potential to delay the need for knee replacement surgery.
- PRP (Platelet Rich Plasma)
- Amniotic/Umbilical Cord Tissue
- Autologous Stem Cells (harvested from fat tissue or bone marrow)
Viscosupplementation (Visco Shots) for Knee Arthritis
Viscosupplementation is the term used to describe knee injections using a compound call hyaluronan (HA). Hyaluronan is a natrually occuring substance in the articular carilage of the knee. This substance has been shown to increase the strength of the cartilage, increase the viscosity of the joint fluid (lubricates the knee), and decrease the oxidative stress within the joint that is associated with osteoarthritis of the knee (OA). Several different companies make similar injections with HA, and the more common ones are Synvisc, Euflexxa, Supartz, Orthovisc, and Gelsyn. These injections used to be made from a rooster’s comb, but are more commonly made in the lab through other processes now. They have a very low rate of complications, and have been shown to delay the need for knee replacement for years. A single series of injections has been shown to last for 6 months to 1 year. Approximately 70-80% of people with mild to moderate arthritis have significant improvements in pain and function, and only 2-4% have negative side effects, almost all of which are temporary. In general, HA injections are most effective as a series of 3-5 weekley injections for patients with mild, chronic arthritis, and low levels of inflammation. Pain relief and functional improvement may be noted within the first week, but it usually takes 6-8 weeks for the full effect to be felt. If significant inflammation or moderate to severe arthritis is present, combined or alternative injections are recommended (PRP and HA, corticosteroids, etc).
PRP (Platelet Rich Plasma) for Knee Arthritis
PRP, or platelet rich plasma, is derived from the patient’s own blood. This can be collected through a routine blood draw in the orthopaedic surgeon’s clinic. The blood is then centrifuged and further manipulated to concentrate it down to the desired level. This derived mixture of the blood, which includes a high concentration of platelets, include multiple growth factors that possess regenerative and anti-inflammatory effects. PRP has been shown to block substances in the knee that breakdown cartilage and to enhance substances in the knee that cause cartilage to grow. Clinical and lab studies have shown that PRP is more effective in protection cartilage than HA (visco). Similar to HA, PRP injections in the knee may delay the progression of arthritis and the need for knee replacement. Pain relief has been shown to be greater with PRP than with HA, and this pain relief has been shown to last up to 12 months. In general, it is recommended to use leukocyte-poor mixture of PRP, and to perform a series of 3 weekly injections every 6-12 months for the treatment of knee osteoarthritis (with or without the addition of HA/visco).
Amniotic and Umbilical Cord Tissue for Knee Arthritis
Recent research has focused on the potential uses for placental tissue, such as amniotic and ubmilical cord tissues, for treatment of various musculoskeletal conditions. The amniotic membrane is the inner layer of the amniotic sac that holds the developing fetus and separates it from the maternal tissues. The umbilical cord is the structure that serves as a super-highway between the mother and fetus, delivering vital nutrients and oxygen. Several FDA-approved products are now available in the U.S. that consist of tissue collected from one or both of these structures. Due to FDA regulations, they are considered “allografts” and while these tissues do normally contain mesenchymal stem cells, the harvested tissue is not considered true stem cell material, and processing likely leaves few living stem cells in the mixture. Much of their effect is thought to be due to the high concentration of growth factors and placental extracellular matrix that is present in the tissue.
The tissue collected for these injections is provided by consenting donors after delivery, and the child and mother are not harmed. These are considered “non-controversial” sources of placental tissue, and it is important to note that this is not the same thing as embryonic tissue. After tissue collection, they are prepared in a way that is amenable to injection using standard techniques. Although there are relatively fewer studies on these tissues than on PRP and Visco/HA, the results are promising. Animal studies have shown that placental extract injections blocked enzymes that are responsible for breaking down cartilage. Similarly, other animal studies have shown that treatment of cartilage injury with placental tissues improves the degree of cartilage healing. Human studies invovling knee arthritis have demonstrated improvement with injections of placental tissue allografts, but no large high quality studies are available yet. The theoretical benefit of using these tissues over one’s own stem cells is that the tissues are younger and may have greater growth potential.
Autologous Stem Cells – Bone Marrow & Fat Derived Cells
Autologous stem cells means stem cells that are derived from one’s own body. The most common sources of these stem cells are those derived from the bone marrow in the pelvis and from adipose (fat) cells within the abdomen. This is usually done as a small procedure in the operating room although it can be done in clinic in some instances. Stem cells have received such prominent placement in popular media because of their potential to differentiate into multiple different types of cells. Their potential to regenerate cartilage and the bone underneath cartilage defects is what makes them so exciting.
Recent studies that have involved the use of bone marrow aspirate concentrate (BMAC), which is obtained from the patient’s bone marrow (usually in the pelvis region), have shown that BMAC injections in knee arthritis patients resulted in significantly improved function and pain. It seems that much of this improvement comes from the increased ability to rebuild the cartilage and fight off inflammatory and degradative cells and enzymes. Similar results were shown for adipose/fat derived stem cells.
Corticosteroid Injections for Knee Arthritis
Corticosteroid injections for the treatment of knee arthritis have been around for over 50 years. It is one of the least expensive and most consistently reliable symptomatic treatments for knee arthritis. However, it’s widespread use has been questioned recently due to suspected detrimental effects to the articular cartilage over time. Corticosteroids inhibit B- and T-cell immune function and thus inhibit the inflammatory effects caused by these cells in the knee. They also may temporarily increase the viscosity of the joint fluid and concentration of HA in the joint. Triamcinolone and Methylprednisolone are the most commonly used of the corticosteroids for knee injections.
The benefits of corticosteroid injections are early and consistent relief of pain and inflammation relatively early after injection. Unlike HA/visco injections which may take 6-8 weeks to fully develop, corticosteroid injections usually provide symptom relief within days. The downsides of corticosteroid injections are that 2-25% of people will develop a post-injection flare (increased swelling and pain), although this does not alter or diminish the therapeutic effect. Other downsides to corticosteroid injections include skin depigmentation, cutaneous atrophy, and fat necrosis around the injection site. There is also increasing scientific evidence that repeated injections may result in cartilage loss. Corticosteroid injections are typically considered as a first line treatment for knee arthritis resistant to other treatments such as NSAIDs, low impact activity modification, weight loss, physical therapy, etc. It is especially recommended in cases of synovitis or other more inflammatory type arthritis. Patients should have no more than 3-4 injections in a year and should consider moving on to visco/HA, PRP, or stem cell injections if they experience a lack of relief from corticosteroid injections.
References for Knee Arthritis Injections
- Musahl V., Murphy C.I., Pfeiffer T.P., Burnham J.M., Gasbarro G.V. (2017) Current State for Clinical Use of Stem Cells and Platelet-Rich Plasma. In: Gobbi A., Espregueira-Mendes J., Lane J., Karahan M. (eds) Bio-orthopaedics. Springer, Berlin, Heidelberg
- The Placenta: Applications in Orthopaedic Sports Medicine; James Alexander McIntyre, BA, Ian A. Jones, BA, Alla Danilkovich, PhD, and C. Thomas Vangsness, Jr, MD; Am J Sports Medicine Vol 46, Issue 1, pp. 234 – 247
- Levy DM, Petersen KA, Scalley Vaught M, Christian DR, Cole BJ. Injections for Knee Osteoarthritis: Corticosteroids, Viscosupplementation, Platelet-Rich Plasma, and Autologous Stem Cells. Arthroscopy. 2018 May;34(5):1730-1743. doi: 10.1016/j.arthro.2018.02.022. Epub 2018 Apr 12. PubMed PMID: 29656808.