Ankle Fusion

Author: K. Zbinden

Definition 

What is ankle fusion?

The ankle, also called the foot joint, forms the connection between the lower leg and the foot and is one of the most heavily loaded joints in the human body. Anatomically, the ankle is divided into two main areas:

• ◉ Upper ankle joint (OSG): It consists of the tibia, fibula and talus. The upper ankle joint mainly enables flexion and extension of the foot.
• ◉ Lower ankle joint (USG): The lower ankle joint is further divided into an anterior and posterior lower ankle joint. It lies between the talus, calcaneus and navicular bone and is responsible, among other things, for rotational and tilting movements.

1. Tibia
2. Fibula
3. Upper ankle joint
4. Talus
5. Posterior lower ankle joint
6. Navicular bone (Os naviculare)
7. Anterior lower ankle joint
8. Calcaneus

An ankle fusion is a surgical procedure in which a painfully damaged joint is permanently immobilized. The medical term for joint fusion is arthrodesis. The aim of an arthrodesis is to eliminate painful movements in the affected joint and thereby improve everyday load-bearing capacity. In the foot and ankle area, different arthrodeses may be considered depending on the findings. In some cases, only the upper ankle joint (OSG arthrodesis) or only the lower ankle joint (USG arthrodesis) is fused. Fusion of both joints is also possible if joint function in the USG and OSG is limited. The goal should always be maximum pain reduction while preserving as much residual joint function as possible.

During ankle fusion, the joint surfaces involved are prepared and then fixed so that they heal together in a functionally favorable position. Screws or other implants are often used for this purpose. Over time, this creates a bony connection between the bones involved. The affected joint remains limited in mobility afterwards, but at the same time pain often decreases significantly. Joint fusion in the foot is therefore considered primarily when conservative measures are no longer sufficient and the symptoms severely impair quality of life.

Schematic representation of an OSG arthrodesis

Ankle fusion is generally not chosen as the first treatment. It is usually considered in advanced joint damage, such as severe osteoarthritis or after complex injuries. Ankle fusion is discussed particularly often when the joint cartilage has been severely worn down and every movement in the joint causes pain. In certain situations, an artificial ankle joint may also be considered as an alternative. Which solution is more suitable depends on several factors, such as age, everyday load, bone quality and whether the upper or lower ankle joint is affected.

Cause of ankle fusion 

The cause of ankle fusion is usually an underlying, very advanced joint damage. Fusion of the ankle is generally considered when the affected joint is permanently painful, unstable or severely restricted in function and conservative measures no longer provide sufficient improvement. The aim of ankle fusion is to eliminate painful movement in the joint and thereby improve everyday load-bearing capacity. The most common causes that can lead to ankle fusion are described below.

• ◉ Osteoarthritis and advanced cartilage wear

  The most common cause of ankle fusion is advanced osteoarthritis. In this degenerative joint disease, the protective cartilage in the ankle is gradually broken down. As a result, the joint surfaces increasingly rub directly against each other. This leads to pain, inflammatory reactions, restricted movement and often increasing malalignment. If the osteoarthritis is severe and every load causes symptoms, an orthopedist may recommend ankle fusion.

• ◉ Previous injuries and consequences of accidents

  Injuries are among the primary reasons why ankle fusion is performed. These include complex fractures in the area of the upper or lower ankle joint, severe ligament injuries, cartilage damage or chronic instability after ankle sprains. Even if such injuries are initially treated, they can permanently alter the joint surfaces, the joint axis or the distribution of load. These changes increase the risk of early cartilage wear, chronic pain and progressive joint degeneration. If joint function is permanently impaired and other therapies are no longer sufficient, joint fusion in the foot or ankle may become an option.

• ◉ Misalignment and uneven load distribution

  Misalignments in the foot and ankle area can lead to uneven pressure distribution in the joint over many years. Certain areas are overloaded while others are used too little. This increases mechanical stress on the cartilage and adjacent structures. Such misalignments can be congenital or develop after injuries, ligament instability or muscular imbalances. Changes in the leg axis or hindfoot can also unfavorably alter the load on the ankle.

• ◉ Inflammatory and rheumatic diseases

  Not only wear and tear, but also inflammatory diseases can be a cause of later ankle fusion. In rheumatic diseases or chronic joint inflammation, long-lasting irritation of the synovial membrane, cartilage damage and structural changes can occur. The joint gradually loses mobility and stability as a result. If inflammatory processes persist over a long period and severely destroy the joint, ankle fusion may be a possible option to reduce pain and achieve stable load-bearing capacity.

Lack of exercise and a sedentary lifestyle as contributing factors

Modern lifestyles are not the direct cause of arthrodeses, but they can promote the development of complaints and degenerative changes that may ultimately lead to fusion. The ankle depends on regular, varied movement in order to remain mobile, resilient and musculoskeletally stabilized. If it is used too little over a long period, several unfavorable adaptations occur.

• ◉ Declining muscular stabilization

  The ankle is guided significantly by muscles, tendons and ligaments. With lack of exercise, active stabilization decreases. As a result, the joint is controlled less precisely, which can increase the load on individual joint surfaces.

• ◉ Reduction in joint mobility

  If the ankle is not used regularly through its full range of motion, it loses mobility. Over time, this can lead to a functional stiffening of the joint. If osteoarthritis or previous joint damage is also present, the situation can worsen further.

• ◉ Increased tension in the joint area

  A sedentary lifestyle promotes shortening and increased tension in the muscle and fascial chains of the legs. These directly influence the position and mobility of the ankle and can intensify malalignment.

• ◉ Worsened joint function in everyday life

  When strength, mobility and coordination decrease, the ankle is subjected to more unphysiological loads in everyday life. In the long term, this can accelerate existing damage and shorten the path to later arthrodesis.

Hard, flat floors and rigid, supportive shoes

Current environmental conditions can also contribute to an unfavorable development in the ankle area. Hard, flat floors and rigid, supportive shoes alter the natural biomechanics of walking and can therefore increase the load on the joint.

• ◉ Increased impact load on the ankle

  On hard, flat surfaces, impact forces are only limitedly cushioned. These forces act directly on the ankle and can increase the stress on the joint surfaces.

• ◉ Restricted natural movement sequence

  Rigid and highly supportive shoes reduce the natural rolling motion of the foot. The inflexibility of floors intensifies this problem, as the foot cannot sink in during heel strike. This often leads to a flat foot placement instead of active rolling. The ankle is then often loaded in similar movement angles while other movement components are hardly used. In the long term, this can contribute to overload and loss of mobility.

• ◉ Reduced active work of the stabilizing muscles

  When modern shoes take over part of the stabilization work, the surrounding muscles are often less challenged. Rigid and flat floors exacerbate this issue because the feet hardly need to adapt to the ground, which reduces muscular activity. As a result, active guidance of the ankle can decrease, which favors malalignment.

Symptoms of ankle fusion 

It is important to mention that the following lists describe the most common symptoms and consequences associated with ankle fusion. The list is not complete or exhaustive, and individual or atypical complaints may also occur. The severity depends, among other things, on which joint was fused, i.e. whether an arthrodesis was performed in the OSG or USG, how far the arthrodesis healing process has progressed, and how well adjacent joints adapt to the changed load.

• ◉ Restricted mobility: The most common sign of ankle fusion is the permanently reduced mobility in the affected joint. Depending on the location, this mainly affects lifting and lowering the foot or tilting and rotational movements.
• ◉ Changed gait pattern: After fusion, the rolling motion of the foot changes. Many affected individuals show an adapted gait because the missing joint movement must be compensated by other joints and structures. Especially after an OSG arthrodesis, it is often noticeable that the rolling motion appears stiffer and less fluid.
• ◉ Load-related pain in adjacent areas: Even if the pain in the fused joint itself often decreases, discomfort can occur in neighboring regions, for example in the midfoot, knee, hip or back. The cause is usually the changed distribution of load.
• ◉ Start-up stiffness: After prolonged sitting or resting, some affected individuals report a feeling of stiffness or insecurity during the first steps. This mainly affects the overall foot and ankle function and not the fused joint alone.
• ◉ Feeling of pressure or residual discomfort after load: Especially during the adaptation phase or during the arthrodesis healing process, discomfort around the operated area may occur after prolonged walking or standing.
• ◉ Swelling in the ankle area: After surgery, swelling may persist for a long time. Even later on, the ankle may swell under load, especially if the foot is not yet fully weight-bearing again.
• ◉ Reduced load-bearing capacity: Prolonged walking, standing, climbing stairs or walking on uneven ground can be difficult. This is especially true in the early phase after surgery or if adjacent joints are already damaged.
• ◉ Uncertainty on uneven ground: If the lower ankle joint had to be fused or the interaction of several foot joints is restricted, walking on uneven ground is often more difficult.
• ◉ Muscle loss and loss of strength: After surgery and during the unloading phase, weakening of the foot and lower leg muscles often occurs. This can additionally affect the feeling of stability and control.
• ◉ Compensatory movement patterns: Many affected individuals unconsciously develop compensatory movements to compensate for the missing mobility. This can overload other joints or muscle groups.
• ◉ Signs of delayed healing or complications: Increasing pain, marked redness, overheating, persistent severe swelling or a lack of increase in weight-bearing capacity may indicate problems in the healing process and should be medically evaluated.

The symptoms mentioned in ankle fusion can occur individually or in combination and may change over time. It is crucial to consider not only the fused joint itself, but also the adaptation of adjacent joints and the overall gait pattern. Good support during the healing process and follow-up treatment is important in order to restore everyday load-bearing capacity as well as possible.

Conventional therapies - What helps with ankle fusion 

Various conventional therapy approaches are available for treatment in connection with ankle fusion. A distinction must be made between whether fusion of the ankle is only planned, whether arthrodesis has already been performed, or whether complaints exist during follow-up treatment. The measures listed below represent a selection of common treatment forms and are not exhaustive. Often several therapy approaches are combined to relieve pain, improve load-bearing capacity and support the arthrodesis healing process. Medical evaluation is recommended in order to determine the appropriate therapy individually.

• ◉ Reduction of load and targeted relief: temporary unloading can help calm irritation in the area of the operated or severely damaged ankle. Load is usually rebuilt gradually and in a controlled manner.
• ◉ Immobilization and splinting: After an OSG arthrodesis or an arthrodesis of the lower ankle joint, a phase of immobilization in a splint or special shoe is often necessary so that bony healing can proceed undisturbed.
• ◉ Cooling: Cold applications can reduce swelling and relieve discomfort in the early phase after surgery or in cases of irritation.
• ◉ Medication: Pain-relieving and anti-inflammatory medications can help reduce symptoms in the short term. This applies both before a planned joint fusion and in early follow-up treatment.
• ◉ Wound checks and medical follow-up: Especially during the follow-up phase after OSG arthrodesis and USG arthrodesis, regular progress checks are important. These assess wound healing, swelling, load-bearing capacity and bony healing progress.
• ◉ Imaging follow-up: X-rays or other imaging procedures are used to monitor the healing process and determine whether the desired bony connection is forming.
• ◉ Physiotherapy: Physiotherapy is a central part of treatment. Although the fused joint itself is not made mobile again, adjacent joints are mobilized, gait is trained and the surrounding musculature is strengthened.
• ◉ Gait training: After ankle fusion, the rolling motion of the foot changes. Targeted gait training helps reduce unfavorable compensatory movements and makes walking more suitable for everyday life.
• ◉ Strengthening exercises: Targeted strengthening of the foot, lower leg and hip muscles improves stability and helps control the changed gait pattern better.
• ◉ Mobilization of adjacent joints: Since other joints must compensate more after joint fusion, it is important to keep the midfoot as well as the knee and hip as mobile as possible.
• ◉ Lymphatic drainage and swelling management: In the case of persistent swelling, suitable measures can help improve drainage and relieve the tissue.
• ◉ Bandages, orthoses or special shoes: Depending on the phase of treatment, stabilizing aids may be useful to protect the joint and control the load.
• ◉ Orthopedic insoles and shoe modifications: After ankle fusion, orthopedic insoles and shoe adaptations are often prescribed to facilitate the changed rolling motion and improve pressure distribution.
• ◉ Planned load increase: After arthrodesis, patience is crucial. Load that is increased too early or too intensively can disrupt the healing process. Therefore, the increase in load should always be adapted to the healing progress.
• ◉ Surgical alternatives: Arthrodesis is not the only option in every case. Depending on age, activity level and joint findings, other surgical procedures may also be considered. These include joint-preserving interventions or, in selected cases, a prosthesis.

Many of these measures are important to relieve symptoms and accompany the healing process. However, they only change the everyday load conditions acting on the foot and ankle to a limited extent. The goal of any treatment should therefore be not only to consider the local situation at the joint, but also to improve gait, muscle activity and load distribution throughout the musculoskeletal system. The kybun mode of action starts exactly here and offers a complementary approach to functional relief in everyday life.

kybun mode of action - What helps with ankle fusion 

The kybun products aim to reduce the health-damaging effects of hard, flat floors and rigid, supportive shoes, as well as actively address lack of exercise and sedentary activities. Thanks to the elastic-springy properties of kybun products, the feet and musculoskeletal system are relieved on the one hand and activated on the other. In the case of ankle fusion, the focus is no longer on mobility in the fused joint itself, but on as favorable a load distribution as possible, a functional gait pattern and relief of the adjacent structures. This is exactly where the kybun mode of action can help.
It is important to note that joint fusion deliberately eliminates movement in the affected joint. The kybun products cannot restore this missing joint movement. However, they can help better absorb the changed load conditions in everyday life and functionally support compensation via the foot, knee, hip and back. Thus, kybun shoes after ankle arthrodesis can be a useful additional aid in everyday life because they can contribute to relief through the following effects:

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

  When stepping in kybun shoes, the elastic-springy material of the sole compresses. This absorbs part of the forces acting on the body. This is particularly relevant in ankle fusion because the missing mobility often leads to harder force transmission. The cushioning can help reduce load peaks when walking and standing and thereby relieve not only the operated area but also adjacent joints and tissues.

• ◉ Time gain for muscular stabilization

  Due to the gentle sinking in at heel contact into the elastic-springy material, the load does not begin abruptly but with a delay. This small gain in time can help the muscles react earlier and in a more controlled manner. This is especially important after arthrodesis, because the fused ankle itself can no longer provide compensatory movement. Better prepared muscles can improve stability while standing and during the rolling motion, thereby relieving adjacent joints and structures.

• ◉ Activation of foot and lower leg muscles

  The elastic-springy sole encourages the foot and leg muscles to make constant fine compensatory movements. This addresses the muscle groups that are particularly important after joint fusion for balance, step control and relieving adjacent structures. More active and stronger muscles can help better control the changed gait pattern after arthrodesis.

Balance and EMG

Balance ability was measured with a force plate by tracking the movement of the body’s centre of mass from front to back (ant-post) and side to side (med-lat) while standing. An electromyography (EMG) simultaneously recorded muscle activity.

With conventional shoes

1. Reduced muscular activity
2. Reduced range of movement of the body's centre of mass

With kybun shoes

1. Increased muscular activity
2. Increased range of movement of the body's centre of mass

• ◉ Support of the rolling motion

  After ankle fusion, the rolling motion of the foot inevitably changes because the possible range of motion in the ankle is limited. kybun shoes with the elastic-springy sole serve in this case as an external rolling aid to make the gait pattern as natural as possible again. This can help reduce unfavorable compensatory movements and distribute the load more evenly across the foot and leg axis.

The rolling function of the kybun sole enables a natural movement sequence over the forefoot. This increases the range of motion of the ankle, gently stretches the joint structures and keeps them flexible, which improves load-bearing capacity. At the same time, malalignment in the ankle is reduced.

• ◉ Protection against fascial dysfunction thanks to a physiological movement sequence

  Despite the reduced or eliminated mobility in the fused ankle, a physiological movement sequence in the foot remains central. An adapted, controlled rolling motion and the active involvement of the muscles promote the function of the surrounding soft tissue structures, especially the fascial tissue. This can reduce tension states and distribute the load on adjacent joints, tendons and ligaments more effectively. This helps prevent malalignment and improve the overall function of the musculoskeletal system in everyday life.

• ◉ Optimized pressure distribution

  When walking and standing in kybun shoes, the sole of the foot is surrounded by the elastic-springy material. This improves pressure distribution. Point load peaks, which occur more frequently after fusion, can be reduced. This can be helpful if, after arthrodesis in the foot, certain areas of the foot are excessively loaded when walking.

with kybun

without kybun

Blue/Green areas: Low-pressure load. Foot soles are protected and put under less pressure.

Yellow areas: Average pressure load. To prevent calluses and pressure points, ensure relief.

Red areas: Excessive pressure. Leads inevitably to chronic strain reactions over longer periods.

• ◉ Promotion of circulation through increased movement activity

  The deliberate instability of the elastic-springy sole and the optimized rolling motion generate more activity, which promotes blood circulation in muscles, tendons and soft tissues. Especially after surgery or during further load buildup, this can support regeneration and help reduce muscular tension and tendencies toward swelling.

• ◉ Promotion of movement and reduction of sedentary behavior

  The kybun products can help affected individuals move more willingly and regularly again. This is especially important because lack of exercise after joint fusion can lead to further muscle weakness, insecurity and unfavorable compensatory patterns. More everyday movement can help improve overall load-bearing capacity.

In summary, the kybun mode of action in ankle fusion is not intended to make the fused joint mobile again. Rather, the aim is to improve the changed load situation in everyday life, support the gait pattern as functionally as possible and relieve adjacent structures. Especially after arthrodesis or in the presence of joint fusion in the foot area, this can be a useful complementary approach.

Application tips for ankle fusion 

Before wearing kybun shoes for the first time after ankle fusion, you should consider a few application tips. Correct use can help better manage the changed load in everyday life and relieve adjacent structures. It is important that kybun shoes are only used once they have been medically or therapeutically approved as part of follow-up treatment.

• ◉ At the beginning, wear the kybun shoes only as long as your body allows. Take conscious breaks from wearing them if symptoms increase or if there is noticeable fatigue in the foot and leg muscles. Especially after joint fusion, the adjustment takes time because gait, load distribution and muscle activity change. Due to the activating properties of kybun products, so-called initial reactions may occur, especially at the beginning.
• ◉ Slowly and in a controlled manner press the heel into the elastic-springy material and feel the flexibility of the sole. Try to find a load point at which the foot feels secure and no unpleasant irritation occurs in the area of the operated joint. After ankle fusion, the rolling motion should not be forced but should occur calmly and in an adapted manner.
• ◉ Take small, controlled steps. Place the foot consciously and securely so that the load is absorbed evenly. Especially at the beginning, make sure that the foot is placed flat and does not tilt inward or outward. This is particularly important after fusion of the lower ankle joint. Also, at the beginning, the rolling motion, which is made possible again thanks to the kybun sole, should be reduced so that the ankle and the structures above it are not overloaded. The reduced rolling motion is particularly important after fusion of the upper ankle joint. As confidence increases, the rolling motion can be gradually increased so that a gait that is as natural as possible is induced.
• ◉ Make sure both legs are loaded evenly. Avoid permanently shifting to the healthy side, as this can lead to additional complaints in the knee, hip or back. The elastic-springy sole can help distribute force more evenly and reduce hard load peaks.
• ◉ Do not force a rapid increase in walking. Increase duration and load gradually so that muscles, tendons and adjacent joints can adapt to the new situation. Patience is especially important after ankle arthrodesis so that the healing process is not adversely affected.
• ◉ Pay particular attention to controlled gait on uneven ground. If the lower ankle joint had to be fused or several foot joints are affected, adapting to uneven ground is often more difficult. Therefore, start as much as possible on level and safe ground and only increase the demands as confidence grows.
• ◉ Combine the use of kybun shoes with targeted exercises. Supplementary strengthening, mobility and coordination exercises support the stabilization of the foot, lower leg, knee and hip. This helps better control the changed gait pattern and enhances the effect of the shoes. The exercises should be performed regularly and adapted to individual load capacity.
• ◉ Observe swelling and load reactions. A slight reaction after unusual load can occur. However, if pain, swelling or insecurity increase significantly, the load should be reduced and the situation clarified by a specialist if necessary.
• ◉ Use kybun shoes as a supplement in everyday life and not as a replacement for medical follow-up treatment. After arthrodesis, medical check-ups, load specifications and, if necessary, physiotherapy remain among the most important foundations for achieving the best possible functional outcome.

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