Knee Osteoarthritis: Symptoms and Treatment of Knee Joint Osteoarthritis

All joints in the body can be affected by osteoarthritis, which is the breakdown or wear and tear of the cartilaginous joint surfaces.

The knee is subjected to particularly high loads. This is why it is frequently affected by osteoarthritis. Knee osteoarthritis is also called gonarthrosis.

Friction within the joint causes the cartilage to become increasingly rough and gradually break down. In severe cases, fragments may break off from the bone or cartilage. The video explains how knee osteoarthritis develops as a result of cartilage damage:

As a result of this degradation process, the joint space narrows. This leads to knee pain, inflammation, and swelling in the knee joint. Consequently, the joint’s range of motion is reduced.

Depending on the section of the joint affected, the following forms of knee osteoarthritis are distinguished:

• Retropatellar osteoarthritis: Degeneration in the patellofemoral joint (the joint between the femur and the patella).
• Medial knee osteoarthritis: Damage to the inner (medial) femorotibial joint (the joint between the thighbone and the shinbone). If accompanied by bowlegs, it is referred to as varus knee osteoarthritis.
• Lateral knee osteoarthritis: Damage to the outer or lateral region of the femorotibial joint. When accompanied by a bowleg deformity, it is called valgus knee osteoarthritis.

In knee osteoarthritis, the articular cartilage is worn down © Henrie / Fotolia

As people age, signs of wear and tear develop in the knee joint (primary osteoarthritis). However, age is not the only risk factor for the development of knee osteoarthritis; other factors include

• genetic factors
• Obesity
• Excessive or one-sided physical or athletic strain
• Misalignments
• Injuries
• Inflammation 

Secondary knee osteoarthritis is diagnosed when the condition results

• an injury,
• disease, or
• excessive strain

.

The typical symptoms of knee osteoarthritis are knee pain that occurs during weight-bearing activities. In advanced stages, the mobility of the knee joint becomes increasingly limited. Swelling develops in the knee, the patient limps, and adopts a protective posture.

Depending on the clinical presentation, knee osteoarthritis can be classified into three stages:

• Stage 1: No symptoms. The osteoarthritis is usually detected only through changes visible on an X-ray.
• Stage 2: Initial pain that worsens with increased movement and improves at rest.
• Stage 3: Persistent pain, even at rest. Significant limitations in movement also occur.

The diagnosis is made based on 

• a detailed medical history (patient interview regarding symptoms and triggers),
• a physical examination (assessment of gait, range of motion, leg alignment, and leg length), as well as
• functional tests (e.g., ligament stability),
• pain tests, and
• X-rays of the knee joint.

In some cases, specialized tests such as

• MRI,
• CT, or
• scintigraphy

may be used. Knee arthroscopy is an important tool for diagnosing and simultaneously treating the damage. The video shows the procedure for knee arthroscopy:

Depending on the stage of the disease, treatment is either conservative or surgical.

Conservative treatment of knee osteoarthritis consists of several steps:

1. Lifestyle adjustments (for example, reducing body weight if necessary and avoiding improper weight-bearing)
2. Physical therapies (e.g., heat or cold therapy)
3. Physical therapy
4. Orthopedic devices
5. Medications for pain relief
6. Acupuncture, if necessary

Surgical options include knee surgery to preserve the joint, stiffen the joint, or replace the joint.

In some cases, arthroscopy may be sufficient for smoothing the cartilage and partially removing accompanying meniscus damage. This requires the presence of localized cartilage lesions. This procedure can ensure years of pain-free living for the patient.

Alignment corrections in the early stages of osteoarthritis can lead to more even pressure distribution within the knee joint.

In cases of advanced knee osteoarthritis, a prosthetic replacement is often the only effective treatment. The patient then receives an artificial knee joint (knee prosthesis).

Specialists in knee osteoarthritis are typically orthopedic surgeons, sports medicine specialists, or rheumatologists.

Further imaging tests (MRI, CT) are performed by specialists in radiology or nuclear medicine.

Clinics for knee osteoarthritis are clinics specializing in

• orthopedics,
• sports medicine,
• joint replacement, and
• knee surgery.

What is the main symptom of knee osteoarthritis?

The classic main symptom of knee osteoarthritis is what’s known as “start-up pain.” Affected individuals experience pain in the knee joint when they stand up after sitting or lying down for a long time and take their first few steps. After walking a short distance, the pain often subsides, but returns with prolonged activity. If the condition is advanced, patients may also experience pain at rest and nighttime knee pain.

How is knee osteoarthritis diagnosed?

The diagnosis of knee osteoarthritis is usually made by a specialist in orthopedics and trauma surgery. The first step is a clinical physical examination to assess range of motion, swelling, and ligament integrity. To confirm the diagnosis of knee osteoarthritis, imaging tests such as standing X-rays are necessary. These typically reveal a narrowing of the joint space and bony growths, known as osteophytes. An MRI can also reveal damage to the meniscus or the cartilage layer.

What causes and risk factors contribute to knee osteoarthritis?

In addition to the natural aging process, being overweight is a key risk factor, as every extra kilogram increases the pressure on the cartilage. Misalignments such as bowlegs (which increase the risk of lateral knee osteoarthritis) or knock-knees (which increase the risk of medial knee osteoarthritis) also lead to uneven stress on the joint. Previous injuries to the meniscus or cruciate ligaments can secondarily trigger knee osteoarthritis years later. Additionally, genetic predisposition plays a role in the development of this degenerative disease.

What does conservative treatment for knee osteoarthritis involve?

Before resorting to surgery, doctors exhaust all options for conservative treatment. These include physical therapy to strengthen the muscles that stabilize the knee joint, as well as weight loss for patients who are overweight. Orthoses or braces can relieve pressure on the joint. Medications such as anti-inflammatory drugs or injections of hyaluronic acid or cortisone directly into the knee joint may be considered to improve the lubricating properties of the synovial fluid and inhibit acute inflammation of the joint capsule.

When is surgery necessary for knee osteoarthritis?

Surgical treatment is usually recommended when knee osteoarthritis is advanced, the cartilage has almost completely worn away (bone-on-bone), and the distress caused by pain and limited mobility significantly reduces quality of life. When conservative measures no longer provide sufficient relief, the implantation of a partial prosthesis or an artificial knee joint (total knee replacement) is often the final step to restore mobility.

What sports are suitable for knee osteoarthritis?

Exercise is important for knee osteoarthritis to nourish the cartilage, but the sport should be gentle on the joints. Recommended activities include cycling, swimming (front crawl), or Nordic walking on soft forest trails. Sports involving sudden stops, jumps, or twists—such as soccer, tennis, or squash—increase the strain on the damaged tissue and can trigger an acute flare-up of knee osteoarthritis, causing swelling and pain.

What is acute knee osteoarthritis?

Activated knee osteoarthritis is an acute flare-up of inflammation within the chronic degenerative process. In this condition, the synovial membrane reacts to cartilage wear by becoming inflamed. The knee becomes warm, red, and swollen, and excess synovial fluid accumulates (joint effusion). At this stage of knee osteoarthritis, the primary focus is on pain relief and reducing inflammation, for example through cooling and rest.

What do professional societies recommend for treatment?

The German Society for Orthopedics and Trauma Surgery, as well as international guidelines, recommend a stepwise approach. The foundation is always patient education, weight loss, and exercise therapy (addressing the causes and treatment). Only if these measures prove ineffective should medication and injections be considered. Joint replacement surgery is considered a last resort once all other conservative and joint-preserving surgical procedures have been exhausted.