Last updated date: 11-Mar-2024

Medically Reviewed By

Interview with

Dr. Sang Soo Eun

Medically reviewed by

Dr. Lavrinenko Oleg

Originally Written in English

Knee Arthrosis Facts - Viewpoints from Expert Doctors

    The knee is the human body's biggest synovial joint, consisting of osseous components (distal femur, proximal tibia, and patella), cartilage (meniscus and hyaline cartilage), ligaments, and a synovial membrane. The latter is in charge of producing synovial fluid, which lubricates and nourishes the avascular cartilage. Unfortunately, because to the heavy usage and stress placed on this joint, it is a common site for painful diseases such as Knee osteoarthritis OA.


    Knee Arthritis Definition

    Knee osteoarthritis (OA), commonly known as degenerative joint disease, is caused by wear and strain and the gradual loss of articular cartilage. It is especially prevalent in the elderly. There are two kinds of knee osteoarthritis: primary and secondary.

    Primary osteoarthritis is defined as articular deterioration with no obvious underlying cause. Secondary osteoarthritis is caused by either an improper distribution of force across the joint, as in post-traumatic reasons or aberrant articular cartilage, as in rheumatoid arthritis (RA).

    Osteoarthritis is a degenerative illness that might eventually cause disability. The severity of clinical symptoms varies from person to person. However, they generally worsen, grow more frequently, and become more debilitating over time.

    Gonarthrosis, commonly known as knee arthrosis, is a condition in which the cartilage in the knee joint gradually wears away. The degradation of cartilage material caused by arthrosis decreases knee stability and can cause significant pain and limited movement.



    Depending on the etiology, knee osteoarthritis is classed as either primary or secondary. Primary knee osteoarthritis is caused by articular cartilage degeneration for no apparent reason. This is commonly thought of as age-related deterioration as well as wear and tear. Secondary knee osteoarthritis is caused by articular cartilage degradation caused by a recognized cause.

    Possible Causes of Secondary Knee OA

    • Posttraumatic
    • Postsurgical
    • Congenital or malformation of the limb
    • Malposition 
    • Scoliosis
    • Rickets
    • Hemochromatosis
    • Chondrocalcinosis
    • Wilson disease
    • Gout
    • Pseudogout
    • Acromegaly
    • Avascular necrosis
    • Rheumatoid arthritis
    • Infectious arthritis
    • Psoriatic arthritis
    • Hemophilia
    • Paget disease
    • Sickle cell disease


    Risk Factors for Knee OA



    • Articular trauma
    • Occupation: prolonged standing and repetitive knee bending
    • Muscle weakness or imbalance
    • Weight
    • Metabolic syndrome



    • Gender: females more common than males
    • Age
    • Genetics
    • Race



    The function of inflammation is not well understood, and there is an ongoing dispute over whether the inflammatory response causes the OA changes or if the inflammation is subsequent to the OA changes. In contrast to inflammatory arthritis, inflammation in OA is persistent and low-grade, involving mostly innate immune systems.

    Synovitis (infiltration of inflammatory cells into the synovium) is a common finding in OA. It can occur in the early stages of the illness but is more common in the later stages and is associated with severity.

    White blood cells are also implicated, and extracellular matrix breakdown produces specific chemicals (damage-associated molecular patterns) that are identified by innate immune cells (macrophages and mast cells), typically as a protective mechanism.

    This prolonged and dysregulated level of inflammation, on the other hand, might result in tissue damage. Macrophages have been reported to be involved in the formation of osteophytes, a pathological characteristic of OA, in animal studies.


    What are Arthrosis and Arthritis?

    Arthritis and arthrosis have similar sounds. Both have an impact on your bones, ligaments, and joints. They also share similar symptoms, such as joint stiffness and discomfort. The distinction between the two, though, is significant.

    Arthritis is a broad word. It refers to a number of diseases that induce joint inflammation. Inflammation can also damage your skin, muscles, and organs in some circumstances. Osteoarthritis (OA), rheumatoid arthritis (RA), and gout are a few examples.

    Arthrosis is another term for osteoarthritis (OA), a form of arthritis. It is the most prevalent form of arthritis. Normal wear and strain on your joints and cartilage cause it. Cartilage is a slick tissue that covers the ends of your bones and allows your joints to move. Your cartilage may degenerate or perhaps vanish altogether over time. This causes bone-to-bone contact in your joints, resulting in discomfort, stiffness, and, in some cases, edema.



    The most prevalent kind of arthritis identified is knee osteoarthritis, and its prevalence will continue to climb as life expectancy and obesity increase. Depending on the source, around 13% of women and 10% of men aged 60 and up have symptomatic knee osteoarthritis. The incidence jumps to as high as 40% among people over the age of 70.

    Males have a lower frequency of knee osteoarthritis than females. Surprisingly, not everyone with radiographic evidence of knee osteoarthritis will be symptomatic.

    According to one research, only 15% of individuals with radiographic indications of knee OA were symptomatic. Without taking age into account, the incidence of symptomatic knee osteoarthritis is around 240 instances per 100,000 persons each year.


    Pathophysiology of Knee Arthritis

    Articular cartilage is largely made up of type II collagen, proteoglycans, chondrocytes, and water. Healthy articular cartilage continually maintains a balance between each of its components, ensuring that any cartilage breakdown is compensated by synthesis. Thus, healthy articular cartilage is preserved. In the course of osteoarthritis, matrix metalloproteases (MMPs), or degradative enzymes, become overexpressed, upsetting the equilibrium and resulting in a loss of collagen and proteoglycans.

    In the early stages of osteoarthritis, chondrocytes produce tissue inhibitors of MMPs (TIMPs) and try to boost proteoglycan production to match the degradative process. This reparative procedure, however, is insufficient.

    The breakdown of equilibrium leads to a decrease in the number of proteoglycans despite increasing synthesis, an increase in water content, a disordered collagen pattern, and, eventually, a loss of articular cartilage flexibility. These alterations cause cracking and fissuring of the cartilage, as well as degradation of the articular surface, at the macroscopic level.

    Although knee osteoarthritis is strongly associated with age, it is crucial to highlight that knee osteoarthritis is not merely a result of aging but is also a disease in its own right. The changes in cartilage found with osteoarthritis and aging corroborate this. Furthermore, the enzymes responsible for cartilage breakdown are expressed at greater levels in knee osteoarthritis compared to normal aging cartilage. 


    Knee Arthritis signs

    Patients usually present to their doctor with the primary complaint of knee discomfort. As a result, it is critical to get a thorough history of their symptoms. Pay close attention to the history since knee discomfort might refer to the lumbar spine or the hip joint.


    Clinical Symptoms of Knee OA

    Knee arthritis pain 

    • Gradual onset 
    • Worse with prolonged activity
    • Worse with repetitive bending or stairs
    • Worse with inactivity
    • Worsening over time
    • Better with rest
    • Better with ice or anti-inflammatory medication
    • Knee stiffness
    • Knee swelling
    • Decreased ambulatory capacity

    A visual assessment of the knee should precede any physical examination. Look for periarticular erythema and edema, quadriceps muscle atrophy, and varus or valgus deformities while the patient is standing.

    Examine your gait for symptoms of discomfort or irregular knee motion, which might suggest ligamentous instability. Next, examine the surrounding skin for the existence and location of any scars from prior surgical operations, overlaying trauma evidence, or soft tissue lesions.

    The range of motion (ROM) test is an important part of the knee assessment. Active and passive ROM in flexion and extension should be measured and recorded.

    Any knee exam must include palpation along the bone and soft tissue structures. The palpatory exam of the knee can be divided into three sections: medial, midline, and lateral structures.


    Diagnosis of Knee Arthrosis 

    A comprehensive history and physical examination, as well as radiographic imaging, are necessary. Standing anteroposterior (AP), standing lateral in extension, and a skyline view of the patella are all recommended views. A standing 45-degree posteroanterior (PA) image of the knee can be acquired, allowing for a more accurate evaluation of the weight-bearing surface of the knee.

    Long leg standing films are occasionally acquired to assess the degree of deformity and general alignment of the lower extremity. It's critical to remember that radiographs of the knee must be taken when the patient is standing. This accurately represents the joint space narrowing that is present.


    Knee Arthritis X-ray

    Imaging techniques can also be utilized to assess the status of the knee joint, namely the cartilage. X-rays may plainly reveal significant wear deterioration. The size of the joint space is given special consideration. The more advanced the gonarthrosis, the smaller it is. X-rays can also identify articular surface deformations (osteophytes).


    Management of Knee Osteoarthritis

    OA is a progressive and degenerative disease with little chance of reversal or repair of damaged components. Thus, current therapy methods are aimed at symptom control until the severity of the condition necessitates surgical intervention with joint replacement.

    There are two types of treatment for knee osteoarthritis: non-surgical and surgery. Non-surgical modalities are used first, then surgical therapy is used once the non-surgical techniques are no longer effective. For the treatment of knee osteoarthritis, a variety of non-surgical options are available. These treatments do not change the underlying illness process, but they can significantly reduce pain and impairment.


    Non-Surgical Treatment Options 

    The goal of OA treatment is to control the painful signals generated by these joints, but more importantly, to enhance functioning and quality of life. As the initial line of treatment for knee OA, non-pharmacological treatments should always be tried.

    • Patient education
    • Activity modification
    • Physical therapy
    • Weight loss
    • Knee bracing
    • Acetaminophen
    • Nonsteroidal anti-inflammatory drugs (NSAIDs)
    • COX-2 inhibitors
    • Glucosamine and chondroitin sulfate
    • Corticosteroid injections
    • Hyaluronic acid (HA)

    Patient education and physical therapy are the first-line treatments for all individuals with symptomatic knee osteoarthritis. The best effects have been seen with a mix of guided workouts and a home fitness regimen. If the workouts are abandoned after 6 months, the advantages are gone. This therapy is recommended by the American Academy of Orthopedic Surgeons.

    Exercise routines should be adjusted to each patient's specific needs/tolerance and preferences, high-impact exercises should be avoided, and long-term adherence should be maximized to enhance results.

    Losing weight is beneficial at all stages of knee osteoarthritis. It is prescribed for individuals with symptomatic arthritis who have a BMI of more than 25. Diet management and low-impact aerobic activity are the best recommendations for weight loss.

    Weight control is crucial in symptom management, and it has been shown that the effect of exercise is amplified by weight loss. Obesity can predispose people to knee OA and has negative molecular and mechanical consequences.

    Unloader-type braces that transfer the weight away from the affected knee compartment are used in osteoarthritic knee bracing. This may be beneficial in cases when the lateral or medial compartment of the knee is affected, such as a valgus or varus deformity.

    For individuals with symptomatic osteoarthritis, drug therapy is also the first-line treatment. There are several NSAIDs available, and the selection should be determined on medical preference, patient acceptance, and cost. The length of NSAID medication should be determined by efficacy, side effects, and prior medical history. According to the AAOS recommendations, there is good evidence supporting NSAID usage.

    Acetaminophen has been proven to be inferior to NSAIDs and not superior to placebo in terms of pain control, prompting some guidelines to avoid recommending it as an effective medical care option for moderate-to-severe OA.

    Topical NSAIDs have been found to be safer than systemic NSAIDs, with equivalent or slightly lower effectiveness. Short-term trials have indicated that they are superior to placebo in reducing pain during the first week of therapy but fail to show effect after 2 weeks.

    The FDA has authorized duloxetine, serotonin, and norepinephrine reuptake inhibitor, for the treatment of diabetic peripheral neuropathy and fibromyalgia. Recent research has shown that when taken for more than 10 weeks, this drug is more effective than a placebo in reducing pain and increasing function in individuals with OA.

    Dietary supplements containing glucosamine and chondroitin sulfate are available. They are structural components of articular cartilage, and it is believed that a supplement will improve articular cartilage health. There is no evidence that these supplements help with knee OA.

    According to the AAOS standards, there is significant evidence opposing its usage. There are no significant drawbacks to using the supplement. It is a reasonably safe choice if the patient knows the research behind these supplements and is prepared to try the supplement. Any improvement from supplements is most likely due to the placebo effect.


    Knee Arthritis Injections 

    Intra-articular corticosteroid injections may be beneficial in the treatment of symptomatic knee osteoarthritis, particularly when there is a significant inflammatory component. The administration of corticosteroids directly into the knee may decrease local inflammation associated with osteoarthritis while minimizing the steroid's systemic effects.

    Another injectable treatment for knee osteoarthritis is intra-articular hyaluronic acid (HA) injections. HA is a glycosaminoglycan that is present throughout the human body and is a key component of synovial fluid and articular cartilage. HA degrades throughout the osteoarthritic process, contributing to the loss of articular cartilage as well as stiffness and discomfort.

    Local distribution of HA into the joint works as a lubricant and may aid in increasing the joint's natural production of HA. Depending on the brand, HA can be generated in the laboratory from avian cells or bacterial cells, and so should be taken with caution in people who are allergic to avian cells. 


    Knee Arthritis Surgery

    • Osteotomy
    • Knee arthroplasty 
    • Total knee arthroplasty 

    For knee osteoarthritis accompanied with malalignment, a high tibial osteotomy (HTO) may be recommended. An HTO is often performed for varus deformities in which the medial compartment of the knee is worn and arthritic. A youthful, active patient who would fail arthroplasty owing to severe component wear would be a good candidate for an HTO. An HTO maintains the real knee joint, including the cruciate ligaments, and permits the patient to resume high-impact activities after healing.

    It does need a longer healing time than an arthroplasty, is more prone to problems, is dependent on bone and fracture healing, is less dependable for pain management, and ultimately does not replace or repair any residual cartilage. An osteotomy can delay the need for arthroplasty for up to ten years.


    Indications for HTO

    • Young (less than 50 years old)
    • Healthy and active patient
    • Non-obese patients
    • Pain and disability interfering with daily life
    • Only one knee compartment is affected
    • A compliant patient who will be able to follow postoperative protocol


    Contraindications for HTO

    • Inflammatory arthritis
    • Obese patients
    • Knee flexion contracture greater than 15 degrees
    • Knee flexion less than 90 degrees
    • If the procedure will need greater than 20 degrees of deformity correction
    • Patellofemoral arthritis
    • Ligamentous instability


    Differential Diagnosis

    In the differential diagnosis of knee osteoarthritis, any probable source of local or widespread knee pain should be explored.

    • Hip arthritis
    • Low back pain
    • Spinal stenosis
    • Patellofemoral syndrome
    • Meniscal tear
    • Pes anserine bursitis
    • Infections arthritis
    • Gout
    • Pseudogout
    • Iliotibial band syndrome
    • Collateral or cruciate ligament injury



    Age, ethnicity, BMI, the number of co-morbidities, MRI-detected infrapatellar synovitis, joint effusion, and both radiographic and baseline OA severity are all predictive of clinical development of knee osteoarthritis. The most severe patients will necessitate complete knee arthroplasty.



    Complications from non-surgical therapy are primarily linked to NSAID usage.


    Common Adverse Effects of NSAID Use

    • Stomach pain and heartburn
    • Stomach ulcers
    • A tendency to bleed, especially while using aspirin
    • Kidney problems


    Common Adverse Effects of Intra-Articular Corticosteroid Injection

    • Skin discoloration at the site of injection
    • Pain and swelling 
    • Infection
    • Elevated blood sugar
    • Allergic reaction


    Common Adverse Effects of Intra-Articular HA Injection

    • Muscle pain
    • Fever
    • Chills
    • Injection site pain
    • Trouble walking
    • Headache


    Rehabilitation for patients with Knee Arthrosis 

    Rehabilitation is an important part of the therapy process for known arthrosis. It is critical for regaining knee function and alleviating discomfort. Extensive physiotherapy is required not just in the conservative treatment of known arthrosis, but also following surgery. Through appropriate workouts, the weaker knee must be gradually repaired. Additional electrotherapy may hasten the healing process substantially.


    To ensure that you get a comprehensive picture and understand everything regarding Knee Arthrosis, we invited Doctor Eun who is a leading doctor at Wooridul Hospital Gangnam to address any questions you may have from an experienced point of view.



    Dr. Sang Soo Eun Interview


    1. Can you please explain a bit about knee arthrosis?

    There are two bones in the knee like this. The femur, then the tibia, and the meniscus between them. As we age, the meniscus begins to tear due to degeneration, and as the bones come into contact with each other, degenerative arthritis occurs. 


    2. The knee joint is arched right? How do you diagnose that?

    The easiest way is to take an X-ray, but in the case of elderly patients who are over 60, when they visit the hospital, their cartilage is already worn out, so we can see the deformation on the X-ray. But now people younger than that have a catching sense of the knee, that is, when they bend and straighten their knee, the inside of the knee hurts or the knee swells. This is a symptom of a meniscus tear. When it comes to such symptoms, X-rays and MRIs are taken to check for cartilage damage inside.


    3. After the diagnosis, if it’s confirmed that it’s a knee arthrosis, what kind of treatment can be done?

    When we say that we have degenerative arthritis, we divide it into stages, first meniscus tear, then early arthritis, and then middle and late stage arthritis. The meniscus tear is also divided and can be repaired with endoscopic treatment by drilling a hole with an arthroscopic menisectomy, which cuts slightly. And it might be in the stage of meniscal repair that needs to be sutured when the cartilage is torn. However, when it is said that the arthritis progresses and becomes worse, if it is the last stage, the final stage of arthritis, artificial joint surgery is performed. Total knee arthroplasty is an operation that removes the bad joint and inserts an artificial joint so that the patient can walk comfortably, and there is a gray zone between them. At this point, there are various treatments. It can be stem cell transplantation, and then, for a patient with varus deformity in which the leg is bent into an O-leg, then HTO or high tibial osteotomy, can be performed to straighten the leg like this. And of course, between the two, you should first try to control the pain by taking medicine and injecting, and in a way, to lose weight and to improve the patient’s symptoms through thigh strength training.


    4. In the case of arthrosis, is there also a way to prevent it? Like a certain posture you should follow, or for example, sports you can do that could help?

    To start with something that can prevent knee arthritis, it is better not to do movements that impact the knee, such as going up and down stairs, and then running a lot constantly like a marathon - these cannot be good exercises for the knee. The knee joint is a weight-bearing joint. Therefore, it is important in our everyday lives to lose weight because the weight is constantly being put on, making it stressed and damaged. Then, it is not the meniscus that absorbs this shock, but the thigh muscles. So doing squats or leg extension exercises to strengthen these thigh muscles can help.


    5. You talked about how you should also reduce your weight in case you’re overweight. So can we say that diet also can affect arthrosis?

    Diet is very important. Losing weight not only reduces knee arthritis, it can also reduce pain.


    6. Is very frequently asked by people. Who is more likely to get arthrosis - women or men?

    Women. Women are more likely to develop osteoporosis after the age of 55-60 due to hormonal problems.

    In men, the legs are often straight like this. But there are many cases of virus deformity in women where their legs are not straight and is bent in an O-shape like this. So, when varus deformity occurs, the medial joint in the knee becomes very narrow, the cartilage is torn, and degenerative arthritis occurs a lot, so there are a lot of degenerative arthritis among women.



    Knee osteoarthritis (OA), commonly known as degenerative joint disease, is caused by wear and strain and the gradual loss of articular cartilage. It is especially prevalent in the elderly. There are two kinds of knee osteoarthritis: primary and secondary.

    Primary osteoarthritis is defined as articular deterioration with no obvious underlying cause. Secondary osteoarthritis is caused by either an improper distribution of force across the joint, as in post-traumatic reasons or aberrant articular cartilage, as in rheumatoid arthritis (RA).

    Osteoarthritis is a degenerative illness that might eventually cause disability. The severity of clinical symptoms varies from person to person. However, they generally worsen, grow more frequently, and become more debilitating over time. Each person's rate of growth is likewise unique. Knee pain that is slow in the start and increases with activity, knee stiffness and swelling, discomfort after extended sitting or sleeping, and pain that worsens with time are all common clinical signs.

    Osteoarthritis (OA) is a prevalent condition that affects the elderly population and is one of the main causes of disability. The prevalence of knee OA is growing as the general population's average age rises. Age, weight, and joint damage from repetitive motions, particularly squatting and kneeling, are all significant risk factors for knee OA. Knee OA is caused by a number of causes, including cytokines, leptin, and mechanical stresses.

    Despite being one of the most studied and common disorders in our society, knee osteoarthritis lacks a defined etiology or a single most effective strategy to treat the symptoms and deterioration associated with it.

    Exercises in the early phases are a beneficial therapy for these individuals, and all medical societies suggest them. Other non-surgical therapies have varied efficacy, and their success is dependent on various aspects (provider, equipment, patient), therefore their usage must be chosen carefully based on the clinical circumstances.

    Conservative therapy for knee osteoarthritis is followed by surgical treatment alternatives if conservative treatment fails. While medicines can help delay the course of RA and other inflammatory diseases, there are presently no approved disease-modifying therapies for the treatment of knee osteoarthritis.