Knee arthrosis

Definition

What is knee osteoarthritis?

Osteoarthritis of the knee joint (gonarthrosis) is a degenerative disease of the knee joint. The knee joint connects the thigh and shin bones and the kneecap. Wherever the knee joint bones meet, those contact surfaces are covered with a layer of cartilage. Healthy cartilage has a very smooth gliding surface that enables low-friction movement in the joint. In knee osteoarthritis, the cartilage is partially damaged. Cartilage damage is divided into four stages:

• Stage/Grade I: Soft cartilage
• Stage/Grade II: Rough surface with fissures
• Stage/Grade III: Deep fissures in the cartilage that reach the bone
• Stage/Grade IV: Complete wear of the cartilage with exposed bone. This is also called a “bone bald spot.”

Where do the pains in knee osteoarthritis come from

Pain intensity and frequency vary greatly from person to person with knee osteoarthritis (gonarthrosis). Often, even for the same person, pain intensity and frequency are very variable. Many people mistakenly assume that only the worn cartilage causes the pain in knee osteoarthritis. The variability of osteoarthritis pain in the knee shows that the pain is not caused solely by the degraded cartilage or cartilage damage. If that were the case, the pain would be relatively constant over time and noticeable with every movement of the knee joint. People suffering from knee joint osteoarthritis often report going from complete pain freedom within a short time to severe pain around the knee joint. This pain variability demonstrates that cartilage health and thickness alone should not be the sole basis for further measures. X-rays and other imaging methods should therefore have no decisive influence on the assessment of the severity of knee osteoarthritis and its treatment. As with all structures in the body, cartilage undergoes continuous breakdown and rebuilding processes. The daily goal must be that the breakdown processes do not outweigh the rebuilding processes. These processes are discussed in more detail later on this page. The variability of pain intensity and frequency is partly related to the fact that areas of knee osteoarthritis can differ. The following regions are distinguished:

• on the inside of the knee joint (medial)
• on the outside of the knee joint (lateral)
• under the kneecap (patellofemoral)

On the other hand, the causes of pain in knee osteoarthritis are also varied because different internal bodily processes occur in knee osteoarthritis. Below are the most common processes explained:

• Cartilage breakdown

  Joint cartilage acts as a shock absorber between the bones of the knee joint. If the cartilage gradually wears away, additional pressure can be placed on the periosteum (the membrane around the bone). The periosteum contains blood vessels and many nerves, which respond to pressure with pain. Unlike bone, the periosteum is very sensitive to pain.

• Joint inflammation (synovitis)

  Cartilage wear can trigger inflammatory processes in the joint lining (synovia). This inflammation leads to increased production of joint fluid and can cause swelling, warmth, and pain.

• Joint effusions

  Increased production of joint fluid (effusion) in response to cartilage loss exerts extra pressure on the joint, which can provoke pain and a feeling of tension.

• Irritation of surrounding tissues

  Changes in the joint also irritate surrounding structures such as ligaments, tendons, muscles, and fascia. This irritation can also cause pain and increased joint stiffness, especially after prolonged rest or at the start of movement.

• Bone changes (osteophytes)

  With progressive knee osteoarthritis, bony growths called osteophytes form at the edges of the joint. These bone spurs are not painful in themselves but can press on nerves or soft tissues, leading to additional pain and movement limitations.

• Microcracks in the bone (subchondral changes)

  As cartilage loss increases, the underlying bone (subchondral bone) is more heavily loaded. This can lead to small cracks, bone hardening, or so-called “geode cysts,” which can also cause pain.

• Myofascial tension

  The musculoskeletal system senses the mis- and overloading of the knee joint and tries to protect the joint and cartilage by tensing muscles and fascia so the knee is no longer moved to its maximum possible extent. This tension of the myofascial structures can cause pain during movement because movement works against this tension.

Cause of knee osteoarthritis

The causes for cartilage breakdown and the associated osteoarthritis pain in the knee are closely linked to modern lifestyles and changed environmental conditions. In earlier times, our ancestors had to move more holistically and much more to obtain food. Hunting, berry gathering, or agriculture are just a few examples. For long distances, this movement was often done barefoot on natural ground. The type of ground and the extent of movement contributed, among other things, to strong foot and leg muscles that were naturally loaded. The lifestyle has changed dramatically over millennia. Modern civilization is often characterized by lack of movement and a sedentary lifestyle. When we do move today, it is due to changed environmental conditions on hard, flat surfaces like concrete or asphalt and in inflexible, supportive shoes. Consequently, the changed quantity and quality of movement leads to bodily adaptations. The following describes how these changes affect the development of knee joint osteoarthritis (gonarthrosis).

Lack of movement and sedentary lifestyle

Modern lifestyles characterized by lack of movement and a sedentary lifestyle lead to maladaptation of the musculoskeletal system. Lack of movement and prolonged sitting cause physical changes that can lead to the breakdown of knee joint cartilage. The following changes play a significant role in the development of knee joint osteoarthritis:

• Weakened musculature

  Lack of movement and a sedentary lifestyle cause essential muscles to atrophy. Foot and leg muscles play a crucial role in the cartilage health of the knee joint. A functional foot musculature supports the longitudinal arch of the foot, which is the first line of defense that reduces force transmission to the knee and thus to its cartilage while standing and walking. Moreover, foot and leg muscles ensure a natural roll-off of the foot and thereby protect against uncontrolled collapse of the foot after heel strike. Uncontrolled collapse of the foot causes the knee to be struck with every step rather than being guided physiologically. This mis- and overloading leads to overuse of the cartilage in the knee joint. The lower and upper leg muscles stabilize the knee joint and keep it in the correct position. Active and tensed muscles around the knee joint further protect the cartilage from impact forces during each movement. Therefore, functioning foot and leg muscles are essential for joint cartilage health.

• Foot malpositions

  Weakened musculature can also lead to foot malpositions. The responsible muscles are no longer able to support the longitudinal arch, resulting in a fallen arch or flatfoot. When the arch collapses, the foot loses its shock-absorbing function while walking and standing. The acting force is transmitted directly through the feet to the knees and their cartilage with each step. The increased load can damage the cartilage over time and lead to knee osteoarthritis and knee pain.
  Furthermore, conditions such as pes valgus (inward collapse), pronation, or supination can shift the knee axis inward or outward, leading to increased loading of the cartilage on the respective side. Persistent one-sided loading can result in cartilage loss in the knee joint.

• Reduced nourishment of the cartilage

  Knee cartilage is not supplied directly by blood vessels but receives nutrients through synovial fluid, which is pumped into the joint through movement. Lack of movement disrupts this process, leading to insufficient supply of nutrients and oxygen to the cartilage. This reduces the cartilage’s elasticity and resilience, increases friction and wear, and can lead to knee osteoarthritis in the long term.

• Fascial dysfunction

  Fascia can change their original structure and become brittle when loaded irregularly and unphysiologically. As a result, the fascial network loses its elastic function and increases tension around the knee joint. Increased tension presses the thigh and shin bones closer together and brings the kneecap closer to the knee joint. This additional pressure from the approximating bones causes excessive cartilage wear. Furthermore, altered fascial structure can impair joint mobility, leading to joint stiffening. More on this in the following section.

• Joint stiffness

  Due to lack of movement and sedentary habits, joints are not moved through their maximal possible range. A natural stiffening of the joints follows. Immobile joints, especially in and around the foot, prevent natural roll-off and therefore increase force transmission to the knee joint. Additionally, the knee joint itself can stiffen, further increasing pressure in and around the knee. The cartilage is thus mis- and overused and can develop osteoarthritis in the knee joint.

Hard, flat floors and inflexible, supportive shoes

Hard, flat floors and inflexible, supportive shoes have a significant impact on the knee joints and can cause or exacerbate knee osteoarthritis. The following factors play a major role in the development of knee joint osteoarthritis.

• Reduced shock absorption and increased force impact

  When walking on hard, flat floors and in inflexible, supportive shoes, higher forces act on the musculoskeletal system, especially at heel strike. Due to the rigidity of industrial floors and the stiffness of conventional shoe soles, the forces cannot be absorbed, leading to increased load on the body. This increased force first impacts the feet and is then transmitted to the knees. The less the feet can absorb forces, the more the knee—the next higher joint—will be loaded. Thus, the cartilage in the knee joint is increasingly affected with each step.
  
  Moreover, due to the increased and earlier force impact, the possible reaction time of the responsible muscles shortens. If the muscles cannot contract in time, the respective joint is inadequately stabilized, which also leads to mis- and overloading. Insufficient muscular tension in the feet results in an uncontrolled collapse of the midfoot after heel strike. The so-called collapsing foot (“Klappfuss”) arises and causes an additional impact on the knee joint, further damaging the cartilage. The stabilizing lower and upper leg muscles also cannot react quickly enough due to the early and increased force impact. Reduced muscular tension leads to an unstable knee joint, increasing cartilage load and eventually causing osteoarthritis in the knee joint.

• Restricted foot function and muscle weakening

  The human knee joint is part of a complex system that coordinates movement from the foot through the leg to the hip. Flexible, natural movement patterns are essential for distributing load evenly and minimizing pressure on the knee. Inflexible, supportive shoes can significantly impair this natural movement. Such shoes artificially stabilize the foot and restrict the mobility of the foot joints. As a result, important muscles and tendons that contribute to leg stabilization are less activated. This can cause increased loading of the knee joints. Long-term overuse accelerates cartilage degeneration and leads to knee joint osteoarthritis.
  
  Studies show that inflexible, supportive shoes are often associated with reduced muscle activity in the calf and thigh muscles. These muscles play a key role in unloading the knee joint. Weakening of these muscle groups increases the risk of malalignment of the knee, which accelerates cartilage wear.

• Unnatural movement sequence

  Natural movement patterns are designed to dynamically respond to varying surfaces. Hard, flat floors and inflexible, supportive shoes make physiological movement sequences much more difficult. On one hand, reduced muscle activation at heel strike causes the foot to collapse uncontrolled. The collapsing foot and its consequences for the knee joint were described in the previous section. On the other hand, the hardness and lack of give of industrial floors and the stiffness of conventional shoe soles prevent natural foot roll-off. Without roll-off, the knee joint is not moved through its full range but is repeatedly loaded in the same zone with each step. This causes some structures to be overused and others underused. In joint cartilage, overly stressed areas undergo excessive breakdown and thus accelerate knee osteoarthritis. Cartilage areas that are not loaded may become brittle and lose their elasticity and damping function. Inflexible, supportive shoes also reduce sensory feedback from the foot, decreasing information exchange and adaptive capacity. This results in monotonous loading that is particularly harmful to the knee joint. The lack of variation and constant pressure on certain parts of the knee can cause microtrauma in the joint that, over time, can develop into knee osteoarthritis.

Symptoms of knee osteoarthritis

It is important to note that the following lists are the most common symptoms of knee osteoarthritis (gonarthrosis). The list of knee osteoarthritis symptoms is not exhaustive. Atypical symptoms are also possible and are not listed here. Symptoms of knee osteoarthritis often depend on factors such as pain perception, cause of injury, degree of damage, physical constitution, etc. To obtain a definitive diagnosis, a physician should be consulted.

• Pain in the knee joint, initially activity-related (e.g., walking, climbing stairs) and later also at rest or at night.
• Joint stiffness, especially pronounced after longer periods of rest (e.g., in the morning, known as “start-up pain”).
• Reduced mobility with difficulty bending or straightening the knee. Limitations in everyday movements, e.g., squatting or kneeling.
• Swelling and inflammation in the knee joint. Inflammation may be accompanied by localized warmth in the knee.
• With severe cartilage loss, bone-on-bone contact can cause grinding or cracking noises.
• Sensation of instability in the knee
• Lack of stability under load.
• Muscle weakness in the surrounding thigh muscles that stabilize the knee.
• Knee misalignments with development of knock-knees (valgus) or bow-legs (varus) due to uneven loading.
• Weather-dependent knee complaints with osteoarthritis. Pain and stiffness can worsen in damp or cold weather.
• Variable pain perception: in the same person, pain can vary within a day from no pain to extreme pain. This is a strong indication that myofascial structures, not just degenerated cartilage, are the cause of pain. Reason: cartilage damage is constant, whereas tension and blockages are not.

Conventional therapy - What helps with knee osteoarthritis

There are several approaches to treat knee osteoarthritis pain. Below are some knee osteoarthritis therapies. This list is not exhaustive. Various measures can also be combined to treat knee osteoarthritis. Medical consultation is recommended to determine the appropriate therapy for osteoarthritis of the knee joint.

• Physiotherapy: With specific knee osteoarthritis exercises and therapy forms, the aim is to improve mobility, strengthen muscles, and relieve the joint.
• Exercise therapy: Gentle training (e.g., swimming, cycling, or yoga) promotes mobility and muscle strength without overloading. It also improves circulation, which is beneficial for knee osteoarthritis treatment.
• Weight reduction: Relief of the knee joints by reducing body weight, thereby decreasing joint pressure, reducing pain, and slowing cartilage breakdown.
• Orthopedic aids: Braces or orthoses to support and stabilize the knee joint. Insoles to correct malpositions and relieve certain joint areas.
• Dietary changes: Anti-inflammatory nutrition to reduce systemic inflammation around the knee joint as an appropriate knee osteoarthritis treatment.
• Acupuncture: Pain relief through stimulation of specific points.
• Heat or cold applications: Heat to relax tense structures, cold to relieve inflammation. The suitable temperature must be tested in knee osteoarthritis treatment.
• Magnetic field or electrotherapy: Promotes blood circulation and relieves pain.
• Medication therapy: Painkillers and anti-inflammatory drugs. Cartilage-building medications for cartilage damage.
• Intra-articular injections: Hyaluronic acid to improve joint lubrication and relieve pain. Cortisone to reduce inflammation during acute flares and relieve pain in knee osteoarthritis.
• Autologous blood therapy: This method uses the healing properties of the patient’s own blood to help regenerate joint cartilage and relieve knee osteoarthritis pain.
• Knee joint osteoarthritis surgery: Arthroscopy with minimally invasive cleaning of the joint, e.g., removal of cartilage debris. Osteotomy to correct malalignment through bone cuts. Knee replacement (partial or total) replacing the knee joint in advanced osteoarthritis.

kybun mechanism of action - What helps with knee osteoarthritis

kybun products aim to eliminate the health-damaging consequences of hard, flat floors and inflexible, supportive shoes, as well as actively address lack of movement and a sedentary lifestyle. Due to the elastic-springy properties of kybun products, the musculoskeletal system is both relieved and activated. The relief ensures that, in an initial step, the load on the knee joint cartilage is reduced. Activation is intended to address the causes of knee osteoarthritis so that knee complaints associated with osteoarthritis become a thing of the past in the long term. Thus, kybun shoes are well suited for knee osteoarthritis, as they help in knee joint osteoarthritis treatment through the following modes of action:

• Muscle activation and stabilization of the knee joint

  When walking in kybun shoes, the heels can sink deeply into the elastic-springy sole thanks to the compressibility of the soles. The sinking builds load slowly and in a controlled way, giving the body more time to activate the relevant muscles. With tensed leg muscles, the knee joint can be stabilized and its cartilage used physiologically. When walking on hard, flat floors in inflexible, supportive shoes, the load strikes the feet without damping. Because of the associated increased force impact and reduced reaction time, the responsible muscles cannot tense quickly enough. Lack of muscle tension results in insufficient stabilization of the knee joint and thus mis- and overloading of the cartilage.

• Reduction of force impact from hard, flat floors through damping effect

  At heel strike in kybun shoes, the elastic-springy material is compressed. Because the kybun sole is compressible, the rearfoot can sink deeply into the elastic-springy material at heel strike. This slow and controlled sinking reduces the forces and thereby the load on the knee joint and its cartilage. Similar to an airbag in a car, the kybun sole helps minimize force impact through its damping effect.

Furthermore, because the heel sinks slowly into the elastic-springy material, the body has more time to tense the relevant muscle groups. Improved baseline muscle tension allows the individual joints to be stabilized and thus reduces force impact on the spine and surrounding structures.

• Activation and strengthening of muscles thanks to elastic-springy properties

  When walking and standing on the elastic-springy kybun surface, the body must constantly make small compensatory movements to maintain balance. The controlled instability of kybun products challenges the balance system and selectively activates the stabilizing deep muscles responsible for stability and posture. This leads to better stabilization and protection of the knee joint by the surrounding musculature. At the same time, coordination skills are trained because the interaction between the nervous system and the muscles is improved. This results in improved body awareness and precision of each movement.

Balance and EMG

Balance ability was measured using a force plate by tracking the center of mass movement from front to back (ant-post) and side to side (med-lat) while standing. In parallel, electromyography (EMG) recorded muscular activity.

By activating and strengthening the foot muscles, foot malpositions such as splayfoot, collapsed (fallen) arch, or pes valgus/varus, which often arise from muscular deficits, can be counteracted. An intact longitudinal arch at heel strike reduces the forces generated, thereby unloading the vertebrae and soft tissues. Preventing inward or outward collapse of the foot keeps the leg axis in its physiological position and protects the back and adjacent structures from additional mis- and overloading. The slow and controlled sinking of the heel into the elastic-springy material creates myofascial pre-tension in the involved muscles. Due to this pre-tension and improved muscle activity, the spine can be stabilized and guided early, which also reduces force impact on the back and surrounding soft tissues.

• Natural foot roll and increased range of motion thanks to rebound effect

Thanks to the elastic-springy kybun shoes with the rebound effect and the associated muscular pre-tension as well as reduced acceleration, the foot can be placed in a controlled manner at heel strike. This prevents the cartilage-damaging collapsing foot that strikes the knee joint with every step. Additionally, active roll-off on the elastic-springy kybun material uses the full range of motion of the foot. The movement sequence begins with heel contact and ends with toe-off. By using the full range of motion in the feet, more movement is automatically generated in the knee joints. Thus, the knee joint is not always moved in the same limited range that promotes cartilage breakdown but is used across its entire range of motion. This results in a reduction of peak point loads. Several studies have also shown that cartilage can rebuild under natural and physiological loading. Using the full range of motion keeps the knee joint mobile and protected from tension and blockages. This additional natural and physiological gait can activate and strengthen muscles and improve circulation, which also has a positive effect on knee joint osteoarthritis.

• Promotion of blood circulation through increased movement activity

  The knee joint also requires numerous nutrients for nourishment, maintenance, and regeneration of cartilage. These nutrients are transported by blood and synovial fluid to the respective tissues. In addition, anti-inflammatory substances are transported to the knee via the blood while harmful and pro-inflammatory signaling molecules are removed. This constant fluid exchange thus supplies the cartilage and keeps it elastic and resilient. The elastic-springy kybun materials promote movement and thereby activate the muscles around the knee joint. In this way, blood circulation is increased, which in turn supports the advantages mentioned above.
  

• Promotion of movement and reduction of sedentary behavior

  The elastic-springy kybun products encourage enjoyment of movement because walking and standing on the unique material relieve the knee joints. Movement activates and strengthens the musculature and promotes circulation. The benefits of these two processes have already been described in previous sections. Since using kybun products can also reduce the duration of sedentary behavior, harmful shortenings and blockages of the myofascial structures can be avoided. More walking and standing stretch and lengthen often-shortened hip flexors and the posterior chain of calf and thigh muscles, which positively affects knee joint angles and pressure on knee joint cartilage.
  

• Care and protection of the fascia

  Fascia stabilize the knee joint and distribute load evenly with every step, thus protecting against cartilage wear. Healthy and functional fascia are elastic and free of adhesions and tensions. Elastic fascia promote knee joint mobility and support good circulation, which is important for nutrient supply and cartilage regeneration. kybun shoes enable a natural movement sequence that keeps the fascia elastic.
  

• Optimized pressure distribution

  When walking and standing in kybun shoes, the entire sole of the foot is surrounded by the elastic-springy material. This leads to optimized pressure distribution in the feet. As a result, point pressure on the knee joints and their cartilage can be reduced. In addition, the constant slight motion on kybun/Joya products increases the load-bearing area, which can also reduce focal pressure points. This helps protect cartilage from injury and wear.

Usage tips for knee osteoarthritis

Before wearing kybun shoes for the first time, you should consider some usage tips. Correct application can help relieve knee osteoarthritis pain. In addition to wearing kybun shoes, treat knee joint osteoarthritis with a targeted therapy program, which is explained in the next section.

• Wear kybun shoes initially only for as long as your body tolerates. Introduce wearing breaks if knee complaints increase or fatigue of the musculoskeletal system occurs. Treating knee joint osteoarthritis takes time. Because kybun products activate muscles, early reactions may occur especially at the beginning.
  
• Press your heel slowly and controlled into the elastic-springy material so that the knee joint is unloaded. Try to find a load point where knee pain is reduced or does not occur. At the start, avoid rolling too far over the heels.
  
• Begin with small and controlled steps, reducing forefoot roll-off to generate less movement in the knee joint. Gradually increase the range of motion of the feet as tolerated.
  
• Try the following exercises to enhance the effectiveness of kybun shoes and increase the likelihood of recovery.

What to do with knee osteoarthritis? Helpful exercises

To enhance the effectiveness of kybun shoes and increase the likelihood of recovery from knee pain, we recommend performing the following exercises for knee joint osteoarthritis. The selection of exercises is not exhaustive and can be supplemented with additional exercises. In general, none of the exercises should increase knee joint pain. If any exercise worsens osteoarthritis pain in the knee, it must be stopped. Pleasant and relieving sensations outside the pain point in the knee joint (e.g., in the thigh) are desirable.

The exercises are divided into the following areas: “Correct walking in kybun shoes,” “Muscle length training,” “Fascia rolling,” and “Strengthening.” Ideally, these areas are used complementarily as therapy for knee osteoarthritis.

Correct walking in kybun shoes

The quality of each step is crucial in the treatment of knee joint osteoarthritis to reduce knee complaints and eliminate mis- and overloading. kybun shoes therefore offer an ideal therapy for osteoarthritis of the knee joint.

Controlled heel strike

• Gently and controlled press the heel into the elastic-springy material to determine load intensity and point without causing knee pain.
• Maintain controlled foot position so the foot does not tip inward or outward. This keeps the knee joint aligned.
• Place the mid- and forefoot slowly and controlled so the knee joint is not struck.
• Slow exercises help rebuild the stabilizing muscles around the knee joint.

Controlled roll-off

• Slight roll-off through the forefoot, without actively pushing off strongly with the big toes at first. The stronger the roll-off, the greater the range of motion in the knee joint. For a tense and blocked knee joint, increasing the range of motion can lead to increased pain. In this case, tensions and blockages must first be resolved.
• Test the possible range of motion of the feet without pain. Increase the range of motion if possible.

Muscle length training
Muscle length training is crucial in treating knee joint osteoarthritis because knee complaints often arise from shortenings, tensions, and blockages of myofascial structures. Targeted stretching exercises can actively address these shortenings, tensions, and blockages and are therefore an ideal therapy for knee osteoarthritis.

Front thigh muscles (quadriceps)

• From standing, grab the dorsum of the left foot with the left hand. For balance, you can hold a stable object with the right hand.
• Left thigh parallel to the standing leg.
• Keep the back straight.
• Tilt the pelvis slightly forward to intensify the thigh stretch.
• Pull the heel of the foot toward the buttock so the knee points downward. The closer the heel is pulled to the buttock, the stronger the stretch.
• Perform 1–2 × daily.
• Hold the exercise 3 x 30 seconds.

Calf and posterior thigh muscles

• Start position in a quadruped (hands-and-knees) position.
• Stretch the buttocks up toward the sky.
• If possible, press the heels toward the floor to increase the stretch.
• Hold 3 x 30 seconds.
• Perform 1–2 × daily.

Fascia roller
Fascial training with the foam roller is important in treating knee joint osteoarthritis because these often result from shortenings, tensions, and blockages of myofascial structures. Regular rolling of shortened and tense myofascial chains makes the foam roller a suitable active therapy for knee joint osteoarthritis.

Front thigh muscles (quadriceps)

• Start position prone (lying on your stomach).
• Place a large roller under the thigh of the extended leg. Place the other leg bent for movement control.
• Roll the front thigh actively from the hip down to just above the knee joint.
• Perform exercises slowly and controlled. Adjust pressure to personal tolerance, but approach a tolerable pain threshold.
• Roll focal adhesions more intensely or hold the position at that point.
• 3 minutes per side.
• Perform 1–2 × daily.

Lateral thigh muscles

• Start in side-lying position.
• Place a large roller between the outer thigh area and the floor.
• Place the upper leg at a right angle to stabilize and guide the movement.
• Roll the lateral thigh actively from the hip to just above the knee joint.
• Perform exercises slowly and controlled.
• Adjust pressure to personal tolerance, but go to a tolerable pain threshold.
• Roll focal adhesions more intensely or hold the position at that point.
• Straightening the upper leg can intensify the exercise.
• 3 minutes per side.
• Perform 1–2 × daily.

Strengthening

Targeted strength training helps strengthen the leg muscles and thus relieve the knee joints and their cartilage. Strengthened muscles can better absorb the forces acting on the knees during movement. Muscles also stabilize the knee joints and protect them from mis- and overloading. Strengthening exercises are an effective therapy for knee joint osteoarthritis and help to reduce knee osteoarthritis pain in the long term.

Squats

• Start position: standing, feet slightly wider than hip-width and slightly externally rotated.
• Slowly and controlled descend into a deep squat. Push the hips back and shift weight to the heels.
• Ensure the force comes from the glutes. Stabilize the knees so they do not collapse inward or outward.
• Slowly and controlled return to standing. If balance is an issue, hold on to a stable object with your hands.
• 3 sets of 8–12 repetitions.
• Perform 2–3 × weekly.

Side-lying leg raises

• Start position: side-lying.
• Feet, knees, hips, and head are in a straight line. A prop can be placed under the head for support.
• Lift the top leg actively and then lower it again in a controlled braking motion.
• At the lowest point, do not fully rest the leg but immediately move it upward again so the muscle remains active. If this is not possible, the leg may be briefly rested.
• Maintain a stable trunk and perform movements slowly and controlled. The upper body should not move.
• To make the exercise harder, place a resistance band just above the knees. The band should sit just above the knee joint.
• 3 sets of 8–12 repetitions.
• Perform 2–3 × weekly.