Artificial knee joint

Definition

What is an artificial knee joint?

An artificial knee joint – also called a knee prosthesis or knee endoprosthesis – is a medical knee replacement that replaces the diseased or damaged knee joint partially or completely. During this type of knee surgery, the worn joint surfaces of the femur, tibia and often the kneecap are removed and replaced with artificial joint components made of metal, ceramic or plastic. A knee replacement restores the sliding and movement function of the knee when conservative treatments no longer provide sufficient relief.

An artificial knee mimics the natural movement sequence of the knee joint: the prosthetic surfaces are shaped to guide the joint stably while allowing as little friction as possible. Depending on the degree of damage, different types of prostheses are used – from partial knee prostheses to complete knee endoprostheses.

Fundamentally, two main groups are distinguished:

• ◉ Total knee endoprosthesis (knee TEP): The standard prosthesis that completely covers the joint surfaces of the femur and tibia in the knee joint.
• ◉ Partial prostheses: When only one compartment of the knee is affected.

Regardless of the model, every artificial knee operation aims to reduce pain, restore stability and improve the knee joint’s mobility in the long term. For an artificial knee to function optimally, the implant selection, positioning and individual anatomy must be precisely coordinated. Modern artificial knees are durable, yet their actual longevity depends on the material, the load and the execution of the knee surgery.

Causes of an artificial knee joint

The need for an artificial knee joint often results from years of poor and excessive loading of the knee joint and the natural wear of the cartilage layer. Modern lifestyles with lack of movement and sedentary work significantly contribute to early degeneration of the knee joint. In the past, our joints were optimally loaded through natural, varied movement on soft surfaces such as meadows and forest floors. Today, however, knees are predominantly loaded on hard, flat floors like asphalt or concrete and are restricted in their natural mobility by stiff, supportive shoes. These conditions weaken the muscles of the feet, lower legs and thighs, and the stabilization of the knee joint becomes increasingly insufficient. The reduced muscle strength directly increases the stress on the cartilage and can lead to premature wear. Moreover, hard, flat floors and stiff, supportive shoes transmit the forces of every single step unfiltered to the knee joints, which overloads the cartilage and accelerates the breakdown process.

In addition, foot misalignments such as flat feet or knock knees can distribute the load on the knee joint unevenly and thus accelerate the mis- and overload that may later necessitate surgery and an artificial knee joint. The cartilage in the knee joint has no direct blood supply and is nourished through movement – meaning the constant alternation of pressure and relief. A restricted supply of nutrients to the cartilage due to insufficient movement additionally reduces its elasticity and resilience. The fascia around the legs and knee joint can also become brittle due to irregular loading and increase the pressure on the knee. The joints themselves lose their full mobility through lack of movement, which further intensifies the burden. Together with the constant load from hard floors and immobile shoes, the risk increases that the knee joint degenerates heavily and eventually requires a knee joint prosthesis.

Consequences and risks of an artificial knee joint

A knee replacement can significantly improve the quality of life but also entails risks and possible consequences. After an artificial knee joint operation, some patients experience pain, especially in the first weeks or months after the surgery. These pains after a knee prosthesis often arise from tissue healing, the adjustment of the muscles to the artificial knee and the strain on the surrounding structures. Some affected people report pain after a knee prosthesis that becomes more intense when climbing stairs or standing for longer periods.

Another possible consequence is limited knee mobility. Artificial knees are restricted in their range of motion compared to a natural knee. This leads to a reduced range, particularly in flexion. The decreased mobility of the knee joint can lead to an altered gait pattern, causing neighboring structures to be mis- and overloaded. Despite state-of-the-art implants, artificial knees can only withstand limited stress, and activities with high impact should be avoided. The durability of artificial knees is also not unlimited. Studies show that a lifespan of about 15 to 20 years is realistic, depending on the patient’s age, activity level and weight. After this period, replacement may become necessary.

Complications such as infections, thromboses or loosening of the knee endoprosthesis are also among the risks. A prosthesis loosening can present itself through pain, instability or swelling and may require another knee surgery. Rarely, misalignments may occur during implantation, which restrict the function of the artificial knee joint and lead to additional complaints.

Conventional therapy - What helps an artificial knee joint

After an artificial knee joint operation or when preparing for a knee prosthesis, there are numerous measures to relieve pain, improve the function of the artificial knee and support healing.

• ◉ Physiotherapy: Special exercises for knee prostheses promote mobility, strengthen the muscles and relieve artificial knees.
• ◉ Movement therapy: Gentle activities such as swimming, cycling or yoga strengthen the muscles and promote circulation without overloading the artificial knee.
• ◉ Weight reduction: Reduces the load on the knee prosthesis and decreases pain after knee prosthesis.
• ◉ Muscle building: Special strengthening exercises for the thigh and gluteal muscles stabilize the artificial knee and support the healing process of the knee prosthesis.
• ◉ Orthopedic aids: Bandages, orthoses or special shoe insoles stabilize artificial knees and relieve them specifically.
• ◉ Dietary change: Anti-inflammatory nutrition supports the healing process and the function of the artificial knee.
• ◉ Acupuncture: Can promote pain reduction after artificial knee joint surgery.
• ◉ Heat or cold applications: Heat relaxes tense structures, cold reduces swelling and pain after knee prosthesis.
• ◉ Electrotherapy: Promotes blood circulation and supports the regeneration of the artificial knee joint.
• ◉ Medication therapy: Painkillers and anti-inflammatory medications can shorten the healing time for an artificial knee joint and alleviate complaints.
• ◉ Gentle daily routine: Avoid stairs, prolonged standing or heavy lifting to relieve the artificial knee joint.
• ◉ Check-ups: Regular follow-up care after knee prosthesis surgery detects loosening or misalignment of the knee endoprosthesis early.

kybun mode of action - What helps an artificial knee joint

The kybun products offer patients after an artificial knee joint operation or with an existing knee prosthesis an effective opportunity to improve the function of the artificial knee while reducing pain. The elastic-springy soles significantly reduce the load on artificial knees as they activate and stabilize the musculature. This supports both the healing process after the artificial knee operation and the long-term protection of the implant.

• ◉ Muscle activation and stabilization of the knee joint

  When walking in kybun shoes, the heels can sink deep into the elastic-springy material thanks to the compressible sole. This slowly and controllably builds the load, giving the body more time to activate the surrounding muscles around the artificial knee joint. A well-tensioned leg musculature stabilizes the implant and allows the most natural load possible on the surrounding structures.
  On hard, flat floors or in stiff, highly supportive shoes, the load acts directly and without damping on the feet. Due to the higher force impact and short reaction time, the muscles around the artificial knee cannot tense quickly enough. The lack of muscular stabilization can lead to an unfavorable force distribution on the implant and the surrounding tissue, thus promoting mis- or overloading.

• ◉ Reduction of force impact on the artificial knee joint

  When the heel strikes in kybun shoes, the elastic-springy material of the sole compresses. Thanks to its high compressibility, the rearfoot can sink deep into the soft sole when stepping down. This slow, controlled sinking reduces the force peaks acting on the artificial knee joint and the surrounding structures. Similar to an airbag in a car, the damping kybun sole helps minimize the force impact and relieve the knee prosthesis with every step, protecting it from over- and misloading.

• ◉ Activation and strengthening of the deep musculature through the elastic-springy property

  Through the slight instability of the elastic-springy surface, the deep musculature is continuously activated and thereby strengthened. These deep muscles play a decisive role in stabilizing the artificial knee joint, posture and balance. At the same time, coordination between the nervous system and the muscles improves, making the movements of the artificial knee more controlled and physiological.

Balance and EMG

The balance ability was measured with a force plate by tracking the movement of the body’s center of gravity from front to back (ant-post) and sideways (med-lat) while standing. At the same time, electromyography (EMG) recorded the muscular activity.

Weak foot muscles or misalignments such as splayed, flat or knock feet can increase the load on the artificial knee joint. By activating the foot musculature in kybun shoes, the longitudinal arch is stabilized, the foot is prevented from rolling inward or outward and the leg axis is held physiologically. This relieves the artificial knee, protects the knee prosthesis from uneven load and reduces the risk of secondary damage to the hip or spine.

• ◉ Natural foot roll thanks to muscle activation and roll-off function

Thanks to the elastic-springy kybun shoes with rebound effect as well as the resulting muscular pre-tensioning and reduced acceleration, the foot can be placed on the heel in a controlled manner. This prevents an abrupt, undamped landing that would unnecessarily stress an artificial knee with every step.
By actively rolling on the elastic-springy material, the entire range of motion of the foot is used: the movement begins with the heel contacting the ground and ends with the toes pushing off. This natural roll-off guides the artificial knee joint through a variable and physiological range of motion instead of always operating in the same limited angle. This reduces localized force peaks and distributes the forces more evenly on the implant and the surrounding structures.
Using the full range of motion helps keep the prosthetic knee mobile and protects it from tension or functional blocks. The more natural gait simultaneously activates the musculature, strengthens it and promotes circulation – factors that can improve the healing process and the pain after a knee prosthesis. Furthermore, the durability of the knee replacement is increased.

• ◉ Improved circulation through increased movement activity

  Even with an artificial knee joint, the surrounding musculature and tissue depend on good circulation to support stability, mobility and healing processes. The elastic-springy kybun materials promote natural movement when walking and activate the muscles around the knee joint.

• ◉ By activating the musculature, the tissue circulation improves, which supports nutrient supply and metabolism in the area of the knee joint. At the same time, this helps to distribute anti-inflammatory substances better and to transport away harmful breakdown products. This keeps the tissue around an artificial knee elastic, resilient and functionally active, which supports wearing comfort and implant stability.
  
• ◉ Reduction of lack of movement and sedentary behavior

  Walking and standing in kybun shoes motivates more movement in everyday life. Tight hip flexors and tense calf and thigh muscles are stretched, the angle position of the artificial knee joint improves and the load on the knee prostheses decreases. This supports the function of the artificial knee in the long term and promotes healing.
  

• ◉ Care of the fascia

  Healthy fascia are elastic, distribute the load evenly and protect the artificial knee joint from excessive strain. The natural movement sequence in kybun shoes keeps the fascia elastic, reduces tension and improves the mobility of the artificial knee.
  

• ◉ Optimized pressure distribution

  When walking and standing in kybun shoes, the entire sole of the foot is encased by the elastic-springy material. This ensures an even pressure distribution in the foot and thus reduces localized loads acting on the artificial knee joints.

Application tips for an artificial knee joint

The use of kybun shoes after an artificial knee joint operation or with existing knee prostheses should be careful and gradual. The goal is to activate the musculature around the artificial knee joint, reduce pain after a knee prosthesis and support the healing process of the knee prosthesis in the long term.

• ◉ Wear the kybun shoes initially only for as long as your body tolerates. Introduce targeted breaks if pain in the artificial knee increases or if the leg musculature becomes fatigued. Due to the activating effect of the kybun soles, so-called initial reactions may occur, which are normal and decrease with continued training.
  
• ◉ Press the heel slowly and controllably into the elastic-springy material. This relieves the artificial knee joint and reduces the impact on the knee prosthesis. Find a load point where the pain in the artificial knee joint is minimal. After the heel makes contact, try to place the foot down slowly and controllably to reduce the load on the knee prosthesis.
  
• ◉ Start with small, controlled steps. Initially reduce the roll-off over the forefoot to limit the movement in the artificial knee. As you become more accustomed, the range of motion of the feet can be gradually increased, which also improves the mobility of the artificial knee.
  
• ◉ Pay attention to signs of overload such as pain, swelling or unusual fatigue in the artificial knee. In this case, reduce the wearing time or adjust the step length. Regular observation helps to keep the application safe and support the healing process of a knee prosthesis.
  
• ◉ Supplement walking in kybun shoes with subsequent exercises to strengthen the stability and musculature around the artificial knee joint as well as to release tension and blockages.

Helpful exercises for an artificial knee joint

To support the effect of the kybun shoes and to promote the functionality of the knee joint with a prosthesis, we recommend performing the following exercises. The selection of exercises is not exhaustive and can be supplemented with other individually suitable exercises.
Important: Each exercise should always be discussed with the treating physician or a medical professional, especially in the case of knee prostheses. In general, the load should not excessively strain the knee joint. If stronger pain occurs in or around the knee, the exercise must be stopped immediately. Light, pleasant tensions or releasing sensations outside the pain area are desirable.

The exercises are divided into the following areas: “Correct walking in kybun shoes”, “Muscle length training”, “Fascial rolling” and “Strengthening”.

Correct walking in kybun shoes

The quality of each step influences the load on the artificial knee joint. When walking, the heels should sink in a controlled manner into the elastic-springy material to reduce the impact forces on the artificial knee. The roll-off across the midfoot and forefoot should initially be slow so that the artificial knee joint is not overloaded. As you become more accustomed, the range of motion of the feet can be increased to comprehensively train the musculature and improve joint mobility.

Controlled heel strike

• ◉ Press the heel carefully and controllably into the elastic-springy material to determine load intensity and point without causing pain in the artificial knee joint.
• ◉ Maintain a controlled foot posture so that the foot does not tip inward or outward and the leg axis stays physiological.
• ◉ Place the midfoot and forefoot slowly and controllably to avoid overloading the artificial knee joint.
• ◉ Slow, deliberate steps strengthen the stabilizing musculature around an artificial knee.

Controlled roll-off

• ◉ Light roll-off on 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 artificial knee joint. If tension and blockages are already present, increasing the range of motion can lead to increased pain. In this case, the tensions and blockages must be released first.
• ◉ Test the possible range of motion while observing pain limits.

Muscle length training
Targeted stretching is crucial, as artificial knee joint pain often arises from shortening, tension or blockages of the myofascial structures. The training improves mobility, reduces pressure on the knee endoprosthesis and supports healing:

Front thigh musculature

• ◉ From standing, grab the top of the foot with the left hand. For balance, hold onto a stable object with the right hand.
• ◉ Left thigh is parallel to the supporting leg.
• ◉ Keep the back straight.
• ◉ Tilt the pelvis slightly forward to intensify the stretch in the thigh.
• ◉ Pull the heel of the foot toward the buttocks so that the knee points downward. The closer the heel is pulled to the buttocks, the stronger the stretch. Explore the range of motion according to the possible mobility of the artificial knee joint.
• ◉ Perform 1 – 2 times daily per side.
• ◉ Hold the exercise for 3 x 30 seconds.

Calf and rear thigh musculature

• ◉ Start position in all-fours.
• ◉ Stretch the pelvis up toward the ceiling.
• ◉ Press the heels toward the floor if possible to intensify the stretch.
• ◉ Hold the exercise for 3 x 30 seconds.
• ◉ Perform 1 – 2 times daily.

Fascial rolling
Training with the fascial roller improves the elasticity of muscles and fascia, relieves the artificial knee joint and reduces artificial knee joint pain:

Front thigh musculature

• ◉ Start position lying face down.
• ◉ Place the large roller under the thigh of the extended leg. Position the other leg bent for movement control.
• ◉ Roll the front thigh actively from the hip down to above the knee joint.
• ◉ Perform the exercises slowly and controlled. Adjust the pressure according to personal sensation but go up to a tolerable pain threshold.
• ◉ Roll intensively over local adhesions or hold the position at that point.
• ◉ 3 minutes per side.
• ◉ Perform 1 – 2 times daily.

Lateral thigh musculature

• ◉ Start position lying on the side.
• ◉ Place the large roller between the outer thigh area and the floor.
• ◉ Position the upper leg at a right angle to stabilize and guide the movement.
• ◉ Roll the lateral thigh actively from the hip down to above the knee joint.
• ◉ Perform the exercises slowly and controlled.
• ◉ Adjust the pressure according to personal sensation, but go up to a tolerable pain threshold.
• ◉ Roll intensively over local adhesions or hold the position at that point.
• ◉ Straightening the upper leg can intensify the exercise.
• ◉ 3 minutes per side.
• ◉ Perform 1 – 2 times daily.

Strengthening

Strong muscles protect the artificial knee joint, absorb forces, stabilize the joint and reduce mis- and overloading:

Squats

• ◉ Start position: standing with feet slightly wider than hip width and slightly externally rotated.
• ◉ Slowly and controllably move into a deep squat. Push the pelvis backward and shift the weight onto the heels.
• ◉ Ensure that the force comes from the glutes. Stabilize the knees so that they do not collapse inward or outward.
• ◉ Slowly and controllably rise again.
• ◉ If there are balance problems, hold onto a stable object with the hands.
• ◉ 3 sets of 8 – 12 repetitions.
• ◉ Perform 2 – 3 times weekly.

Leg lifts in side-lying

• ◉ Start position: lying on the side.
• ◉ Feet, knees, hips and head remain in one straight line. A prop can be placed under the head for support.
• ◉ Actively raise the upper leg and then lower it again in a controlled braking movement.
• ◉ At the lowest point, do not fully rest the leg but move it upward again so that the musculature remains active. If this is not possible, the leg can be briefly rested.
• ◉ During the exercise, maintain a stable torso and perform the movements slowly and controlled. The upper body should not move.
• ◉ To increase the challenge, place a resistance band (fitness band) around the knees. The band should sit just above the knee joint.
• ◉ 3 sets of 8 – 12 repetitions.
• ◉ Perform 2 – 3 times weekly.