The meniscus is a c-shaped piece of cartilage in the knee that functions as an important shock absorber. It is sandwiched between the thigh and shin bone. There are two menisci per knee. One on the inside portion of the knee (medial) one on the outside aspect (lateral).
The knee meniscus is susceptible to injury. The most common injury is a tear in the meniscus. Not all meniscus tears however cause pain. When symptomatic a meniscus tear can cause pain, swelling, and restriction in range of motion.
Causes of Knee Meniscus Tears
Tears in the knee meniscus can arise from trauma or degeneration. There are many different types of meniscus tears based upon locations. They are categorized based on the shape of the tear. Examples include radial, horizontal, and bucket handle tears. To learn more about the 6 different types of Meniscus tears please click here.
Meniscus tears typically do not occur in isolation. Rather they occur with other injuries such as ACL, PCL, and MCL tears and sprains.
Over 30 years old, your meniscus can weaken. It is common for people with tears in their meniscus to have damage from squatting or stepping movements. However, when an older person experiences a meniscus tear, it is more likely due to the deterioration of their cartilage. This can cause the knee to be weaker and easier to tear. If you have osteoarthritis, you are more likely to injure your knee or tear your meniscus. However, according to Boston Children’s Hospital, meniscus tears are becoming more common in children. This is because children are participating in organized sports at an earlier age.
Diagnosing Meniscus Tears
A torn meniscus often can be identified during a physical exam. Your doctor might move your knee and leg into different positions, watch you walk or squat to help pinpoint the cause of symptoms. In addition, MRI and X-rays are effective for determining if you have a meniscus tear or not. In-office ultrasound is an effective, low-cost option to evaluate the knee meniscus. Ultrasound is a great option as it can identify the presence and severity of knee meniscus tears.
What are the Symptoms of Meniscus Tears?
Back of Knee Swollen
Back of knee swollen? Swelling in the back of the knee is not something that is talked about too often. It can be uncomfortable or sometimes painful with the movement of the knee or, even with rest. It often stems from an orthopedic-related issue or, perhaps some other medical condition. Let’s dive in…What’s Causes Swelling in the Back of Your Knee?
The back of the knee contains a variety of anatomical structures that can be affected and result in pain, swelling, numbness, tingling, etc. Muscles and tendons behind the knee that could be the source of pain or pathology could be one or more of the following: Gastrocnemius, Soleus…
Stiffness in the back of the knee can be a sign that there is damage or inflammation in the joint, arthritis, or a baker cyst. This might be due to an injury, overuse, or medical condition. If you are experiencing stiffness in your back knee, it is important to see a doctor determine the cause and get treatment. Common causes of stiffness in the back of the knee include: tight muscles, tendons, and ligaments, Injury to the joint or surrounding tissue, overuse such as from running or biking for long periods. Stiffness at night can potentially indicate damage to the joint…
There are many possible causes of burning pain on the outside of the knee while kneeling. One possibility is that you may have patellofemoral syndrome, which is a condition that results in pain around the kneecap. This pain can be aggravated by activities such as kneeling or squatting. Other potential causes of this type of pain include iliotibial band syndrome, runners knee, and meniscal tears.
If you are experiencing burning pain on the outside of your knee while kneeling, it is important to see a doctor for evaluation. Some of these conditions can be treated with conservative measures such as rest, ice, and physical therapy…
Your knee is capable of moving in a number of directions. The most common are flexion and extension. Flexion is when you bend your knee and the shin bone moves towards the buttock. Knee extension is when you straighten out your knee. The extension is the opposite of flexion. PT, trainers, and physicians alike measure the degree of knee flexion and extension. When lying flat on an examination table or hard surface your knee should be able to extend so that there is no angle between the thigh and shin bone. The inability to straighten the knee is also known as an extension lag and is a reason for concern.
Knees can buckle, causing a sensation of one or both knees giving out that affects nearly 17% of adults. The knees are regarded to be one of the most essential (and biggest) joints in the human body because they play significant roles in basic activities such as walking and sitting. When our knees begin to feel unstable, weak, or begin giving out, it is easy to become stressed since we rely so heavily on them for movement.
The knee can become stable from numerous types of injuries. The knee is kept stable by the following structures: Tendons attach the leg muscles…
Your knees bend countless times throughout the day. Running up the stairs, down the hall after kids, and getting into the car. You straighten the knee as you walk, descend stairs or get into and out of the car. Bending and straightening the knee are necessary for daily activities. Knee pain with bending or straightening may be a mild, transient irritation or may indicate a more significant problem. Learn more below and avoid further injury and dysfunction.
Knee pain can vary significantly depending upon many factors including the actual source of the pain, the severity of the injury, general health, and level of activity…
Knees have the ability to bend forward and back, as well as rotate slightly. When a knee is unable to execute these actions, it impairs mobility and the capacity to complete daily chores such as sitting, standing, squatting, or kneeling. A locked knee occurs when a knee cannot be bent or straightened so it gets stuck or feels locked in a certain position for an extended period of time.
There are two forms of locked knees: one that is due to inability to move because of an actually physical or mechanical restriction and there is one that feels locked due to the pain involved in moving it. When a person has their knee joint effectively frozen into place and cannot move, this is known as a true locked knee….
Knee pain can be caused by many factors. Overuse injuries, direct trauma to the knee and arthritis are the most common causes of knee pain. Damage to the knee structures may cause swelling, scar tissue formation (fibrosis), and loss of function of the joint. Pain is often accompanied by difficulty walking, weakness, and instability.
When the knee is overused, the thigh and shin bones (femur and tibia), cartilage, or tendons may experience stress. This leads to pain and discomfort as well as stiffness in the knee. Overuse injuries are common among athletes who participate in sports that involve running, jumping…
Knee popping can be a sensation that something is moving around in the knee. There may also be an audible sound associated with the popping, which in medical terms is called crepitus. This can also cause what we call mechanical catching or locking, which may make the knee feel like it is stuck in an extended or flexed position, and you have to move it in certain ways to get out of that. This knee popping sensation or sound or could be a very simple issue or it could be a sign that more serious damage is going on in the knee, so determining what is causing it is very important. So, the knees may pop and get in a certain position….
Swelling of the knee, also known as water on the knee, is a condition in which fluid collects around the knee joint. Swelling can occur for a variety of reasons and affect patients of any age. Some swelling can be treated with over-the-counter medicines, but persistent and continuous swelling might result in tissue damage, bone softening, and cartilage deterioration. Over-the-counter medicines will assist relieve pain for individuals with a history of osteoarthritis and swelling following physical activity, such as exercise or running. During and after activity, the patient may apply compression sleeves to reduce the inflammation. Ice is another method…
What causes outside knee pain? How do you treat it? Let us go over all of this and also review how one patient avoided a huge surgery. What is On the Outside of the Knee? You have a couple of key structures here (1). They include the: Lateral meniscus, Lateral joint compartment, Popliteus tendon, Iliotibial band, Lateral collateral ligament , and anterolateral ligament, and Fibula. The meniscus is a figure-8 shaped fibrous structure (shown here from above) that is a shock absorber for the knee joint. It has an outside part (lateral meniscus) that cushions the joint. The meniscus can become torn or degenerated. If you are young…
First off, this is where the hamstrings and calf muscles attach. They have tendons here that are inserted into the bone. So if there’s a problem in the muscle or the tendon, you’re going to feel it right here. This is also where deep muscles like the popliteus and plantaris live. So, if these have issues, you’re going to feel it in the back of the knee. In addition, the tibial nerve is back here. So if there’s an issue with a nerve in your back or a nerve locally, behind the knee, you’re going to feel it here. And the meniscus or the joint spacer lives back here. And the meniscus or the joint spacer lives back here. So a tear in the meniscus could cause pain…
A knee can feel stiff if there is some swelling in or around the joint or muscle tightness can caused restricted motion This can occur from a problem in the knee joint, such as inflammation, arthritis, or infection, or an injury.
The distance and direction that a joint may move are referred to as its range of motion. Various joints in the human body have specific normal ranges set by doctors and therpists.
One study, for example, found that a normal knee should be able to bend to between 133 and 153 degrees. A typical knee should also be able to extend fully straight.
Limitation of motion occurs when a person range of motion in any limb is reduced below the normal range….
What could tightness in your knee mean? When fluid builds up inside the knee as a result of an injury, overuse, or medical problem, the knees become swollen and tight. Swelling might be mild, so you may not always notice it unless it is serious damage. You may feel this as stiffness in the knee since swelling may not be visible.
Swelling restricts movement since there is less room in the knee. Fluid buildup can be caused by irritation, internal bleeding, and injuries to the knee. Arthritis, gout, tumors, and baker cysts are all causes of swelling. Pain and swelling are the responses of your body to damage. Together they can lead to stiffness in your knee…
Weakness in the knee can be a symptom of many different knee conditions. Some of the most common causes of weakness in the knee include ligament tears, meniscus tears, and arthritis. Another important but often overlooked cause of knee weakness is irritation or injury of the nerves in the low back. If you are experiencing any type of weakness in your knee for long durations of time (3 weeks), it is important to see a doctor to determine the cause.
Some of the most common symptoms of knee weakness include difficulty standing up from a seated position, difficulty walking, climbing or descending stairs…
6 Types of Meniscus Tears and Their Treatment Options
1. Horizontal tear (Longitudinal)
This is an up and down or front to back tear in the meniscus. Many times these tears are in a portion of the meniscus that does get blood supply (red zone) so could potentially heal on their own. Physical therapy is a first-line treatment that often works. If they do not heal naturally or with physical therapy, then the arthroscopic surgical repair can sometimes be tried to help. A surgical meniscectomy should NOT be done for these types of tears as they can make the knee worse. PRP (platelet-rich plasma) or bone marrow concentrate (BMAC) containing stem cells can heal these tears as an alternative to surgery. These are more natural, safer, and have easier recovery than surgery so these should be done prior to considering surgery in most cases. They can also be used in conjunction with surgery to improve surgical results.
2. Radial tear (transverse)
This is a left-to-right tear across the meniscus. These are the most common types of tears. Most commonly they are in what we call the white zone of the meniscus where it does not get much blood supply. Thus, they are hard to heal naturally. PT should still be the first line treatment but these may benefit more from PRP or bone marrow concentrate (BMAC). If you see a surgeon, they will likely try to cut this part out (meniscectomy) despite the evidence saying that a meniscectomy does not work and can make the knee worse, so this rarely should be done for these types of tears.
3. Intrasubstance tear (incomplete)
Usually, these are degenerative tears in the midportion of the meniscus. After age 30, these are very common findings of a meniscal tear on MRI, which is of little consequence. Physical therapy is the first-line treatment. Typically, if you have pain, it will be from other knee issues such as arthritis. For mild to moderate arthritis, PRP has excellent evidence it can help. If the arthritis is more moderate to severe then BMAC will be a better treatment option. Most surgeons will not even try to operate on these as surgery doesn’t help and meniscectomy can make the knee worse.
4. Bucket-handle tear
This is a tear where the meniscus is torn and flipped over like a bucket handle. These sometimes can cause some catching or alter the motion of the knee. If that is the case then those would be the rare type of tear that actually would need surgery if that is the case. Typically, a meniscectomy is done as these may not respond to repair. If this type of tear doesn’t have the mechanical symptoms or knee catching/locking, then it possibly can be helped with physical therapy, PRP, or BMAC.
5. Flap tear
This is where a small piece of the meniscus can be torn and flipped over. Sometimes this can cause some catching of the knee, sometimes it does not hurt. If there is no catching in the knee, then it would not warrant any surgery to remove that part of the meniscus. Physical therapy would be a first-line treatment, with PRP or BMAC being an option. If it is causing some catching or altering motion of the knee that might be another rare case where surgery is indicated for partial meniscectomy as these are difficult to repair.
6. Complex tear
The last of the types of meniscus tears is the complex tear, where you have a combination of different tears where it can be torn in multiple areas of the knee. Oftentimes when the surgeon sees these, they would attempt a meniscectomy again because most of the time these are difficult for them to try to repair.
On MRI and or to some degree with ultrasound, you can determine where the meniscus is torn. This is important to know for treatment and to determine if the tear matches with a patient’s pain.
Anterior horn: front part of the meniscus
Body: mid portion of the meniscus
Posterior horn: back part of the meniscus
Root: front or back deeper part wear the meniscus attaches to the tibia
Risk Factors for a Torn Meniscus
The meniscus can be torn with sports, high-intensity exercise, trauma. Risks would be being overweight, low physical activity levels, or doing too high of intense exercise without being in proper shape, or having incorrect form/biomechanics. Typically, movements like knee twisting, deep knee bending, rotating the knee can predispose to injury.
Natural Remedies For a Torn Meniscus
If you have knee pain and have been told you have a suspected meniscal tear either from an exam or from MRI, much of the time, this can heal on its own with 4-6 weeks of rest, doing some physical therapy that would focus on some range of motion and strengthening exercises and correcting maybe any biomechanical problems that may stem from the core, back, hips or the ankles. Nutritional support such as just working on a healthy diet, reducing inflammation in the body, taking some turmeric, fish oil, glucosamine, and chondroitin, can help knee pain and inflammation as well.
Revolutionary Treatments For A Meniscal Tear Without Surgery
If you go to most pain practices if you fail physical therapy and surgery is not yet recommended, they may recommend a steroid injection, which can help temporarily reduce inflammation in and around the knee and meniscus, but this is not advised as steroids as we know can cause damage to the joint cartilage, inhibit healing, and has a host of other negative side effects.
An injection of something called hyaluronic acid, which is a part of some of the lubricating fluid of the knee joint could be used for temporary pain relief. It does not help repair the area but may provide a few months of symptomatic benefit if there is not severe arthritis in the knee.
Meniscal surgery actually doesn’t have any evidence that it help meniscal tears and does have clear evidence that it can progress arthritis faster (1-7).
If you actually want to try and get the body heal that meniscus on its own where rest and physical therapy did not do the job, PRP has excellent evidence that helps with meniscal injuries as well as mild to moderate arthritis that can be associated with these. PRP when used in the right hands, should be injected precisely with ultrasound guidance into the torn parts of the meniscus, into any ligaments or tendons that may be injured or loose and into the knee joint itself for optimal results. Many practitioners just inject into the knee, which still can help quite a bit but not as much than if a more thorough approach is taken. There are more than 25 high level studies showing PRP helps with knee pain (Orthopedic Bone Marrow Stem Cell Historical Timeline (netdna-ssl.com)).
Bone marrow concentrate that contains stem cells within it can also be used for more severe meniscal tears or if there are meniscal tears with more moderate to severe arthritis. There are a few randomized control trials that show that this can be helpful for that as well (8-10). Again, you want to have a thorough skilled approach to make sure that image guidance is used, and all of the damage parts of the meniscus and associated areas of the knee such as tendons, ligaments, and joints are injected as well.
The other day I was evaluating a patient and reviewing the treatment options for their spine condition. After discussing prior treatments, we got to the topic of medications taken for pain relief. She explained that she mainly utilized anti-inflammatory (NSAID) medications and then she told me to hold much she takes and has been for many years…..she takes close to 2 grams (2000 milligrams) on a daily basis which equated to about 9-10 capsules of medication per day. I was shocked, considering she was pre-diabetic and with high blood pressure plus the kicker of it is that her PCP (primary care physician) is ok with this…
PRP stands for Platelet-Rich Plasma. Platelets are blood cells that prevent bleeding. They contain important growth factors that aid in healing. Plasma is the light yellow liquid portion of our blood. So PRP is simply a concentration of a patient’s own platelets that are suspended in plasma and are used to accelerate healing. PRP is NOT stem cell therapy. Regrettably, blood contains few circulating stem cells. Rich sources of stem cells are bone marrow and fat. PRP is rich in growth factors. There are many different types of growth factors with different properties. VEGF is a very important one as it can increase the blood flow to an area.
Doctors Who Assist with Meniscus Tears at Centeno-Schultz Clinic
Christopher J. Centeno, MD
Christopher J. Centeno, M.D. is an international expert and specialist in Interventional Orthopedics and the clinical use of bone marrow concentrate in orthopedics. He is board-certified in physical medicine and rehabilitation with a subspecialty of pain medicine through The American Board of Physical Medicine and Rehabilitation. Dr. Centeno is one of the few physicians in the world with extensive experience in the culture expansion of and clinical use of adult bone marrow concentrate to treat orthopedic injuries. His clinic incorporates a variety of revolutionary pain management techniques to bring its broad patient base relief and results. Dr. Centeno treats patients from all over the US who…
My passion and specialization are in the evaluation and treatment of cervical disc, facet, ligament and nerve pain, including the non-surgical treatment of Craniocervical instability (CCI). I quit a successful career in anesthesia and traditional pain management to pursue and advance the use of PRP and bone marrow concentrate for common orthopedic conditions. I have been a patient with severe pain and know firsthand the limitations of traditional orthopedic surgery. I am a co-founder of the Centeno-Schultz Clinic which was established in 2005. Being active is a central part of my life as I enjoy time skiing, biking, hiking, sailing with my family and 9 grandchildren.
Dr. Pitts is originally from Chicago, IL but is a medical graduate of Vanderbilt School of Medicine in Nashville, TN. After Vanderbilt, he completed a residency in Physical Medicine and Rehabilitation (PM&R) at Emory University in Atlanta, GA. The focus of PM&R is the restoration of function and quality of life. In residency, he gained much experience in musculoskeletal medicine, rehabilitation, spine, and sports medicine along with some regenerative medicine. He also gained significant experience in fluoroscopically guided spinal procedures and peripheral injections. However, Dr. Pitts wanted to broaden his skills and treatment options beyond the current typical standards of care.
Post-residency, Dr. Markle was selected to the Interventional Orthopedic Fellowship program at the Centeno-Schultz Clinic. During his fellowship, he gained significant experience in the new field of Interventional Orthopedics and regenerative medicine, honing his skills in advanced injection techniques into the spine and joints treating patients with autologous, bone marrow concentrate and platelet solutions. Dr. Markle then accepted a full-time attending physician position at the Centeno-Schultz Clinic, where he both treats patients and trains Interventional Orthopedics fellows. Dr. Markle is an active member of the Interventional Orthopedic Foundation and serves as a course instructor, where he trains physicians from around the world.
Doctor Hyzy is Board Certified in Physical Medicine and Rehabilitation (Physiatry) and fellowship-trained in Interventional Orthopedics and Spine. Dr. Hyzy is also clinical faculty at the University of Colorado School of Medicine in the Department of Physical Medicine and Rehabilitation; In addition, Dr. Hyzy is an Adjunct Clinical Assistant Professor at The Rocky Vista University College of Osteopathic Medicine. Dr. Hyzy also maintains an active hospital-based practice at Swedish Medical Center and Sky Ridge Medical Center. He is also recognized and qualified as an expert physician witness for medical-legal cases and Life Care Planning. He is published in the use of autologous solutions including…
Dr. Money is an Indiana native who now proudly calls Colorado home. He attended medical school at Kansas City University and then returned to Indiana to complete a Physical Medicine and Rehabilitation residency program at Indiana University, where he was trained on non-surgical methods to improve health and function as well as rehabilitative care following trauma, stroke, spinal cord injury, brain injury, etc. Dr. Money has been following the ideology behind Centeno-Schultz Clinic and Regenexx since he was in medical school, as he believed there had to be a better way to care for patients than the status quo. The human body has incredible healing capabilities…
Dr. Mairin Jerome is a physiatrist with subspecialty fellowship training in Interventional Orthopedics and Regenerative Medicine. This subspecialty serves to fill the gap for patients who are interested in therapeutic options that lie between conservative treatment and surgery. Dr. Jerome uses regenerative medicine techniques, including prolotherapy and orthobiologics, via X-ray or ultrasound guidance to precisely deliver injections to areas of musculoskeletal injury or degeneration. Orthobiologics refers to tissue harvested typically from a person’s own body, such as platelets (platelet-rich plasma, PRP) or bone marrow, for use in treating painful musculoskeletal conditions. The goal is to stimulate the body’s healing mechanisms to improve pain, function, and decrease inflammation.
This e-book by Dr. Chris Centeno examines the knee and its role in the human musculoskeletal system and the body as a whole. The Knee Owner’s Manual provides a series of tests and clearly defined exercises that you can perform on your own to assess and monitor your own knee health. It will allow you to look for trouble spots where your own body may be having difficulty with stability, articulation, symmetry, and neuromuscular function. You’ll be able to see how these deficits in other regions of the body relate to the knee.
The Knee Owner’s Manual also discusses how Regenexx is pioneering the development of interventional orthopedics, a new branch of medicine that employs regenerative biologic therapies such as adult bone marrow concentrate and platelet-rich plasma to help repair and strengthen damaged tissues in other areas of the body.
This is contrasted with invasive knee surgeries, which often remove important tissues or replace the entire knee itself when it becomes damaged. With hyperlinks to more detailed information, related studies, and commentary, this book condenses a vast amount of data, images, and resources into an enjoyable and informative read. This is the first edition of The Knee Owner’s Manual, a companion book to Orthopedics 2.0.
Even a small meniscus tear can make walking difficult for you. If you are experiencing any of these symptoms, you may want to seek medical help as soon as possible, depending on the type of tear you have. Needless to say, a lot depends on understanding the meniscus tear types there are and what each … Continued
If you have, or suspect you have a torn meniscus, and you’re wondering how to heal a torn meniscus naturally, you’ve landed on the right post. You may be wondering: Do I need surgery? Can you heal a torn meniscus naturally? The short answer is: It depends. What Is a Meniscus? The meniscus is a … Continued
Your knee pain initially was intermittent and mild. Unfortunately, It is now constant and debilitating. Your doctor recommends knee replacement surgery. What is the knee composed of? What are the most common knee injuries? What is knee replacement surgery? What are the different types of knee replacements? What is knee replacement surgery success? What are … Continued
Dr. Chris Centeno discusses how to read a knee MRI for meniscal tears and what you need to know about such tears. Transcript Hi, this is Dr. Centeno. And I’d like to go over today How to Read Your Knee MRI: Focus on the Meniscus. I have a whole series of these and reading a … Continued
Walking became impossible. Each step was associated with severe pain. Knee replacement seemed like a good solution. Unfortunately, months after the surgery problems exist. Your doctor thinks you have a loose knee replacement. What is a knee replacement? What causes a knee replacement to become loose? What are the 7 most common symptoms of a … Continued
Transcript for “How to Read Knee MRI” Hi, this is Dr. Centeno and I’d like to go over how to read knee MRI. I got the idea for this when a friend had a knee injury, got an MRI, was sent home with the CD, and just jumped on the internet to try to figure … Continued
Katz JN, Brophy RH, Chaisson CE, et al. Surgery versus physical therapy for a meniscal tear and osteoarthritis [published correction appears in N Engl J Med. 2013 Aug 15;369(7):683]. N Engl J Med. 2013;368(18):1675–1684. doi:10.1056/NEJMoa1301408
Sihvonen R, Paavola M, Malmivaara A, Itälä A, Joukainen A, Nurmi H, Kalske J, Järvinen TL; Finnish Degenerative Meniscal Lesion Study (FIDELITY) Group. Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. N Engl J Med. 2013 Dec 26;369(26):2515-24. doi: 10.1056/NEJMoa1305189.
Sihvonen R, Englund M, Turkiewicz A, Järvinen TL; Finnish Degenerative Meniscal Lesion Study Group. Mechanical Symptoms and Arthroscopic Partial Meniscectomy in Patients With Degenerative Meniscus Tear: A Secondary Analysis of a Randomized Trial. Ann Intern Med. 2016 Apr 5;164(7):449-55. doi: 10.7326/M15-0899.
Netravali NA, Giori NJ, Andriacchi TP. Partial medial meniscectomy and rotational differences at the knee during walking. J Biomech. 2010 Nov 16;43(15):2948-53. doi: 10.1016/j.jbiomech.2010.07.013.
Cohen SB, Short CP, O’Hagan T, Wu HT, Morrison WB, Zoga AC. The effect of meniscal tears on cartilage loss of the knee: findings on serial MRIs. Phys Sportsmed. 2012 Sep;40(3):66-76. doi: 10.3810/psm.2012.09.1983.
Longo UG, Ciuffreda M, Candela V, Rizzello G, D’Andrea V, Mannering N, Berton A, Salvatore G, Denaro V. Knee Osteoarthritis after Arthroscopic Partial Meniscectomy: Prevalence and Progression of Radiographic Changes after 5 to 12 Years Compared with Contralateral Knee. J Knee Surg. 2019 May;32(5):407-413. doi: 10.1055/s-0038-1646926.
Katz JN, Shrestha S, Losina E, Jones MH, Marx RG, Mandl LA, Levy BA, MacFarlane LA, Spindler KP, Silva GS; MeTeOR Investigators, Collins JE. Five-year outcome of operative and non-operative management of meniscal tear in persons greater than 45 years old. Arthritis Rheumatol. 2019 Aug 20. doi: 10.1002/art.41082.