Amputation Technique and Prosthetic Treatment

Amputation technique and prosthetic treatment

When choosing an amputation technique it is necessary to understand whether the amputation wound will be closed immediately or in a second operation.

In this case one speaks of a closed or an open operation. The open amputation, or the so-called two-stage amputation, is usually performed during war and catastrophic events and is associated with significant disadvantages such as soft tissue and muscle retraction and dehydration of the bones.

However, thanks to various drainage and vacuum techniques, the stump is seldomly left completely open.

The most important amputation principle is to save as much of the the extremity as possible, since the longer the lever, the better control the patient has over their prosthesis.

Unfortunately, this general rule has some restrictions in certain situations. First step is to determine the amputation level. In general, the amputation is performed through the tissues that will heal well and at the level where all pathologically changed parts will be removed.

Usefull Information About Amputation Technique and Prosthetic Treatment

When determining the amputation level in case of a poor blood circulation, the blood flow of the skin flaps is considered to be more important than the condition of large vessels.

If joints are going to be spared therefore allowing for a better mobility, the tissue perfusion must be accurately determined.

In the area of the or the lower leg the question is whether the knee joint can be spared or not.

When treating extensive bone tumors, it is important to take into consideration that it can be spread much further than it was seen on the X-ray or the scintigraphy and a bigger part of the bone must be amputated than was initially assumed.

In addition to the task of saving as much limb as possible, it is also important to ensure that the stump can be covered with sufficient amount of normal sensitive and scar-free skin. Because the insensitive or transplanted skin poorly tolerates the pressure from a prosthesis and will most likely fail. This problem mainly affects the lower extremity, as it bears heavy load. This is also an issue in traumatic injuries with burns and abrasions. An exception are children, because in their case a stump with an actively growing joint (epiphyseal plate) must to be covered with skin, as the skin transplants are less sensitive.

It is also important to cover the stump with muscles. In this case, if it is difficult for the surgeon to sew the opposite muscle groups above the bone without creating tension, he must shorten the bone to ease the seam.

Large muscle vessels must be individually separated by transecting the muscle tissue, smaller ones can be occluded thermally.

In order to avoid the formation and consequences of benign but painful nerve knots (neuromas), which can occur due to the separation of a nerve, the nerve must be separated as close to the body as possible, otherwise the compression of the neuroma by the prosthesis can cause severe pain.

The bone is closed in the bone cavity (marrow cavity) through suturing of the periosteum strips, the bone is also extended and stabilized using periosteum or bone chips. The aim is, among other things, to protect, for example, the lower leg tibia and fibula using a stable bone connection before its compression by the prosthesis.

During the operation, the patient is normally treated under general anesthesia. An arresting bleeding tourniquet is necessary to ensure clarity and to avoid greater blood loss in larger amputations. With the help of a tight cuff, which is placed above the amputation area, the blood is kept away from the operated area. However, if the cuff stays for too long, it may cause tissue destruction.

When the operation is complete, one or more drainage hoses are introduced into the surgical area to remove the wound fluid from the muscles and bone surface. After a few days, the drainage can be removed. A special pressure bandage is used to stimulate the wound healing.

If there is an infection risk, for example after a trauma or a vascular disease, an antibiotic should be administered prophylactically during or before the surgery.

In the case of an arm amputation, greater functional and psychological disturbances occur compared to an amputation of a lower extremity.

It is also more difficult to achieve optimal prosthetic restoration, since the prosthesis stability is achieved not the same way that its mobility.

The bigger the segment of the limb is lost, the more often patients with amputated arm do not want to have a prosthetic restoration, in case of unilateral amputation at the shoulder level (shoulder disarticulation), the prosthesis is usually rejected.

The arm prosthesis treatment has a tradition that dates back to the Middle Ages. Since the world wars, in addition to cosmetic arm prosthetics (cosmesis), there are mechanical arm prosthetics. Nowadays, patients can move their myoelectric prostheses using muscle electrical signals from their arm stump.

What is an arm prosthesis?

A prosthetic arm serves as a cosmetic and functional replacement of an upper extremity.

The history of prosthetics goes back to the Ancient Egypt. Even before Christ, there were smaller prostheses that replaced lost toes. The beginnings of the arm prosthesis dates back to the Middle Ages. In the 16th century, for example, the first iron hands were made of metal, and in addition to cosmetic functions also complied with some functional requirements. At that time, the individual joints of the iron hands were still passive and had to be bent and straightened using the healthy hand.

In the 20th century, arm prosthesis became more and more significant for war victims. A major breakthrough was the Sauerbruch's arm prosthesis, which was developed at that time by the surgeon Ferdinand Sauerbruch. Jakob Hüfner improved the Sauerbruch's arm prosthesis and thus the first actively moving arm prosthesis was born. During the World War II, Lebsche successfully developed the Sauerbruch's idea. The today's myoelectric arm is also based on the functional principle of the Sauerbruch's arm prosthesis. One should distinguish between prostheses and epitheses, the latter serve purely aesthetic purposes.

Shapes, kinds & types

In the 21st century, arm prosthesis are divided into cosmetic arms and working arm prosthesis.

Cosmetic arms serve aesthetic purposes only. They replace the missing arm visually and produce an integer and symmetrical image.

Much more expensive than cosmetic arms are myoelectric working arms, which can be actively moved using the electrical signals generated by muscles at the connection point of the prosthetic. With some practice the patient is able to grab and open, as well as stretch and turn the prosthesis.

Myoelectric arm prostheses nowadays also have a pleasant aesthetic appearance. For a long time, the metal prostheses were only covered with leather. Today the outer skin-like cover is made either of PVC or silicone. Currently, the most expensive option is a silicone glove with nylon reinforcement. These arms are stable, dirt-repellent, tearproof and relatively resistance to abrasion. In general, a silicone coating with nylon reinforcement must be replaced every six months.

In addition to prosthetic forearms, there are also myoelectric upper arm prostheses. Hybrid prostheses are to be distinguished from these open implants. These closed implants do not replace the lost limb, but only a damaged joint and are completely surrounded by body tissues.

Structure & working principle

The most sophisticated form of an open arm prosthesis is the myoelectric arm. This type of prostheses are powered by a battery. The elements are moved by the contraction of the muscles in the stump.

Myoelectric arm prostheses are controlled by a surface electrode. This electrode conducts an electromyogram from the bioelectric muscle tensions in the microvolt level. Then, these are converted into motor control signals, wherein these are matched with control signals of the prosthetic motor. The muscular strength is proportional to the myogram. In simple terms, the number of all activated muscle fibers is relatively proportional to the applied force.

The efficiency of myoelectric arms depends on how many control signals can be used for sequential control. Ideally, despite the amputation, the prosthesis holder should still be able to contract individual muscle groups. The tension of the individual muscles can be measured on the skin via electrodes which makes the individual prosthetic joints arbitrary controllable.

The first myoelectric arm for commercial purposes was developed in the USSR during the 1960s. The technique behind the myoelectric arms is based on the Sauerbruch's arm prosthesis, as at that time Sauerbruch had placed a canal in the remaining muscle tissue of the arm stump. A pin was placed in this channel over which the muscle contraction of the arm stump was transferred to the prosthesis.

Medical & Health Benefits

The myoelectric form of arm prosthesis fulfil well its health purposes. They restore the movability of the extremity that has been lost due to amputations, malformations or accidents and war injuries.

Just a century ago this development was hardly imaginable. Even then, prostheses were already equipped with metal joints, but could not be actively moved. Since the Sauerbruch's arm, a lot has changed in prosthetics and the prostheses have even higher medical benefits for an even larger number of people.

Although the prices for myoelectric prostheses are still relatively high and therefore not everyone can afford such a fully functional prosthesis, the fitting of a movable arm prosthesis has since become at least safer. While the construction with pin was expected to have surgical complications and cause severe infections, the risk of infection with today's systems is low.

In addition to the functional benefits, modern arm prostheses are very important psychologically. Many patients after an amputation are confused by how different their appearance is. Some suffer from depression and have difficulties with their everyday life. With today's relatively lifelike arm prostheses, you will certainly be having an active social life.

Cosmetic arms that have been serving this purpose have a long tradition and have been manufactured centuries ago to relieve patients from psychological problems caused by amputation and to simplify their reintegration into social life. Nevertheless, for a long time cosmetic arms were very noticeable and hardly had the impression of a real arm. From a distance a modern arm prosthesis looks like a real limb.

Leg prostheses are used to replace a missing leg. The integration of mechanical joints lead to a breakthrough in leg prosthetics. Modern prostheses restore the most of dynamic leg functions and allow the patients to lead a quality life.

What is a prosthetic leg?

A leg prosthesis is used after amputations or in the case of a leg deformity after the restoration of a functional limb. The first leg prosthesis was made of wood and thus allowed an ideal friction. This is still the most important criterion characteristics of a prosthetic legs.

The first prostheses had limited mobility. They served as a support, but could not be actively moved. After the First World War the value of prosthetics rose due to the numerous war injuries. In the field of arm prosthetic, the first active prostheses were developed where the joints could be moved without the aid of the healthy arm. The first prosthetic legs with knee joints were developed at about the same time. The first bioelectronic knee joint was integrated in the so-called C-leg prosthesis.

This was the the first leg replacement designed by Otto Bock company, which gave the thigh amputees an option to run. The world's first active prosthetic legs is an invention of the turn of the millennium. This so-called power knee is an adaptive and electromechanically-operated model of prosthesis that measures the pulses from the healthy leg and provides them to the motor of the prosthesis.

Shapes, kinds & types

There are two main types of prosthetics: closed and open implants.

  • Closed implants are joints that are completely covered by healthy tissues.
  • On the other hand, open leg prostheses are required if the whole extremity is lost.

Open implants can be passive and since the 2000s there are also active prostheses. Depending on which parts of the leg are affected by amputation or deformity, physicians distinguish between lower leg prostheses, foot prostheses and thigh prostheses.

Patients with amputated toes, amputations up to the midfoot or of the entire feet receive foot prostheses.

The lower leg prostheses are designed for lower limb amputees. Different systems are used for these prosthetic forms. The most common type is the short prosthesis with a so-called adhesion system. The patient pulls a liner over the stump and then pulls it into the firm prosthetic socket using the liner.

The thigh prostheses are used if the whole leg was amputated. This type of prosthesis requires complex systems that replace the knee joint. Today, various socket models and liner types are available allowing different artificial leg constructions.

Structure & working principle

Leg prostheses take over the loads when the person is standing and ensure standing safety. Apart from that they are able to take over the dynamic functions of the amputated or missing leg and also improve the patient's gait giving a largely natural appearance of walking motion.

In addition to a hydraulic system, leg prostheses are also equipped with controllers, that substitute the brain control.

For example, the leg must know that the carrier is standing to stabilize and to give the support for a safe standing. It also needs to know when the patient is going and in what walking phase he is at the moment.

The C-leg was the first thinking leg prosthesis to meet these demands. Using special sensors, this prosthesis continuously collects data to determine the walking phase. An angle sensor detects the flexion angle. A moment sensor with a pipe adapter determines the direction of the load. The motor and the hydraulic valve of the prosthesis are connected to the sensors and are activated and coordinated using the data from the processing controller. Since the controller needs just a few seconds to process the collected data, the swing phase and the standing phase can be adjusted in real time and the lower leg swing matches, for example, the walking pace during running.

Other prosthetic legs use a fluid system with a magnetorheological liquid mass instead of a hydraulic system combined with a controller. The particles in the oil-like liquid change their viscosity proportionally to the strength of the magnetic field according to the sensor data.

The active power knee is an even further development of the dynamic prosthetics. These prosthetic legs contain special sensors on the sole of the foot, which immediately recognize the gait and adjust the power of the motor to correspond to it.

Medical & Health Benefits

Losing an arm causes fewer restrictions than losing a leg. The healthy arm can compensate for the loss of its counterpart and to a certain degree take over its functions.

Such compensation is more difficult if a leg is lost. The great decrease in mobility happens if a leg is lost. Patient is not only unable to walk, but also to stand safely with only one leg. Prosthetic limbs bring enormous medical benefits.

Nowadays especially the active prostheses play an irreplaceable role in prosthetic limb replacement. Movement is a complex process. Smooth walking is ensured by countless interconnections of the nervous system and the motor tracts. Thanks to the progress of the technology age this safety mechanism can be mimicked today using sensor controller systems with a motor.

In the beginning of leg prosthetics development wooden prostheses without joints were able only to take on supporting functions, but the dynamic functions were still very limited. The innovations in leg prosthetics enable people with amputated limbs to live more independently and actively. They give patients an increase in quality of life.

One must also not underestimate the visible aesthetic effect of a prosthetic leg, relieving the patients from psychological burdens.

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