The upper limb prosthesis is used to replace the whole or part of the upper limb. In the field of prosthetic technology, the upper limb prosthesis has a special significance. The loss of any part of the upper limb will cause physical, life, work and social obstacles to amputees, especially the bilateral amputation. Because the function of normal human hand is very complex, the action is extremely dexterous, the feeling is very sharp, at present any exquisite mechanical and electronic structure is difficult to replace. The requirements for the upper limb prosthesis are first to restore the main functions of the hand and forearm to the maximum extent and to achieve self-care of life, and then to make up for the defects in appearance. After efforts, the upper limb prosthesis can replace the human hand in function and beauty, so that the amputee can recover certain life self-care and work ability.

According to the view of modern rehabilitation medicine, first, some amputations are not only destructive surgery, but also constructive surgery. Second, amputation is not the end of medical treatment, but the beginning. After surgery, if we want to restore the function, we need to create a new moving organ. This organ (STUMP) can drive the scientifically made prosthesis, so that the preserved joints can move freely. This requires the cooperation of doctors, prosthetic makers, patients and family members, so as to avoid the only goal of ensuring the wound I phase healing cooperation. Pathology is not the only factor in determining the plane of amputation. Other factors should be considered, including anatomical, surgical, prosthetic and sociological factors such as age, gender and occupation of individuals. Each of the above factors plays a certain role in determining the amputation site, but the key factors are different for each amputee.

Selection of amputation site of upper limb

The amputation site (plane) is directly related to the prosthesis assembly, compensatory function, patients' self-care and employment ability. Compared with the traditional concept, the choice of amputation position has changed significantly. The important trend of the choice of amputation position of upper limb is to keep the long stump as much as possible under the premise of the treatment of the disease, so as to ensure the maximum function of the stump.

Partial amputation

Including finger amputation and hand amputation, the length of the amputated finger (end) should be preserved as much as possible, the feeling of the amputated finger (end), the grip strength of the hand, the accusation (thumb, index finger) and the function of holding the object. For the thumb with serious injury, we should try to keep it without amputation. The amputation of fingers or palms should be covered with good flaps to prevent infection and cicatricial adhesion and create conditions for functional reconstruction in the later stage of the hand.

Carpal disjunction

The wrist joint is severed, the stump is relatively long, and its distal end is expanded. All of these are conducive to maintaining the stability of the prosthesis suspension. At present, the traditional decorative correction method for the distal bone end is no longer used.

Forearm amputation

Long stump refers to those whose length is more than 55% of the total length of the forearm, 35-55% of the total length of the forearm, and extremely short stump refers to those whose length is less than 35%. The rotation of forearm, the flexion and extension of elbow joint and the strength of elbow joint can be basically preserved when the lower and middle part of forearm is amputated. The length of the stump should be kept as much as possible, even if it is a very short broken end. The longer the stump is, the greater the leverage function is, and the more the rotation function is retained. If the distal end of the forearm is oval, the rotation function of the prosthetic hand can be exerted. If the muscles of the stump are retained, good EMG signals can be obtained, which is very beneficial for assembling the EMG prosthetic hand.

Amputation of elbow joint

In the case of necessity, elbow joint disconnection is an ideal amputation site, because the prominent condyle of the humerus is conducive to the suspension and rotation control of the prosthesis.

Upper arm amputation

The function of the upper arm prosthesis depends on the length of the lever arm, muscle strength and the range of motion of the shoulder joint. Long stump is good for suspension and control of prosthesis, and the length should be kept as much as possible.

Amputation around shoulder joint

Shoulder amputation, in addition to the shoulder joint amputation, there are the whole shoulder amputation, shoulder band amputation, the scapula, clavicle and the muscles attached to it are amputated. Because the supporting points of the prosthetic receiving cavity are all destroyed, it is very difficult to wear the prosthetic for the shoulder amputation. The humeral head should be preserved as much as possible to achieve a better appearance. The round shape of the shoulder can increase the fitting range of the prosthetic receiving cavity at the same time, which is helpful for the elbow and hand activities.

Classification of upper limb prosthesis

The history of the research on the upper limb prosthesis is is much later than that of the lower limb prosthesis, because the upper limb prosthesis can only compensate for two or three functions of the human hand. With the development of science and technology, the technology, material, manufacture and assembly technology of upper limb prosthesis are improving and developing day by day. All kinds of prostheses are emerging, ranging from beauty hand, tool hand to EMG prosthesis. According to the classification method of performance, structural characteristics and dynamics, the upper limb prosthesis can be divided into passive type and active type.

Passive upper limb prosthesis

The passive upper limb prosthesis refers to the joints of the prosthesis, such as hand device and wrist, elbow joint can only move passively, but not be controlled by the patient or external force source. The passive upper limb prosthesis can be divided into two types: the decorative upper limb prosthesis and the instrumental upper limb prosthesis. Among them, the decorative upper limb prosthesis can only reconstruct the appearance, which is suitable for those who explicitly give up wearing functional upper limb prosthesis, but only pay attention to make up for the defects in the appearance of the limb. This kind of prosthesis only pays attention to the lifelike appearance, comfortable wearing, light weight and easy operation. Decorative prostheses are suitable for all amputation planes, especially for patients with high amputation.

Active upper limb prosthesis

The joint of active upper limb prosthesis can move actively, and it can be divided into two types: self powered upper limb prosthesis and external powered upper limb prosthesis.

Self powered upper limb prosthesis: it refers to the upper limb prosthesis which is provided by the amputee to control the movement required by the prosthesis. At present, most of the prostheses produced at home and abroad are self powered prostheses. The cable-controlled upper limb prosthesis is a typical self powered prosthesis. Cable controlled upper limb prosthesis, also known as active grasping arm, is usually called mechanical prosthesis or manipulator, which is a kind of upper limb prosthesis with indirect force source. Its movement function is achieved by the movement of the disabled limbs and the control system of the shoulder belt. In order to make all kinds of functions coordinated, patients are also required to carry out a lot of training. The cable controlled upper limb prosthesis is suitable for all amputation plane stumps except the hand. But it is difficult to use this kind of prosthesis for high amputee, especially for the amputee of shoulder joint. The strap control system of the forearm prosthesis only controls the hand device, so the functional movement, elbow bending and elbow locking of the amputation above the elbow joint plane are controlled by the triple or double control system. In addition to the use of these prostheses on both sides, they can also be used in combination with passive prostheses or EMG prostheses. It is of great significance to adhere to the upper limb training with the use of the rope controlled prosthesis. Patients should learn to control the different functional movements of the prosthesis, and even strive for a certain degree of feedback.

External force source upper limb prosthesis: it is also called external power upper limb prosthesis, which is driven by electric, pneumatic and other external power. In the upper limb prostheses, the development and application of the external force source prosthesis is earlier and there are many kinds. It is developed to overcome the inconvenience of the manipulation of the mechanical prosthesis with the traction cable, and to solve the difficulty of some amputees to install the cable-controlled prosthesis. As the application of human body bionics, the external force source upper limb prosthesis has attracted more and more attention of engineering and technical personnel in biophysics, precision machinery, automatic control and other aspects. Many major achievements have been made, including electric hand (switch control hand, electromyographic control hand) and pneumatic hand.

Mixed type upper limb prosthesis: it refers to the upper limb prosthesis controlled by self force source and external force source at the same time, which is used for patients with high-level upper limb amputation. The prosthesis is controlled by electromyography, elbow joint is controlled by strap, and internal and external force sources play a role together.