The rigid determination of the amputation height by so-called amputation schemes with division into valuable, dispensable and obstructive limb sections, which was carried out in the past, is now outdated and must be rejected. With the various amputation heights and forms, the extent to which the residual limb is able to bear weight and suitable for receiving a prosthesis must be taken into account.
Amputation hand, elbow and shoulder
On the upper extremity, amputation through the shoulder girdle, i.e. between the shoulder blade (scapula) and the chest (thorax), is the highest point of possible removal. Here, a malignant tumour is usually the cause and causes considerable cosmetic and functional damage. The consequences of a shoulder disarticulation, i.e. an upper arm amputation from the shoulder joint, are similar.
In the case of an amputation of the humerus, care must be taken to ensure that sufficient space is left for an artificial elbow joint. Disarticulation (amputation) in the elbow joint itself is difficult, since protruding bone parts can cause painful pressure points in the prosthesis shaft. The hands are capable of complex fine motor movements and are extremely important for daily life and work, so that an amputation leads to considerable impairment. In the hand area, in addition to resilience, the residual limb length, sensitivity, joint mobility and possible gripping shapes must also be considered. Even the loss of a thumb makes gripping processes hardly possible.
Amputation leg, foot, lower leg
In the area of the lower extremity, the form of loading is naturally different from the upper one. In the case of metatarsal and tarsal amputation, care must be taken to ensure that the particularly strong skin of the sole of the foot and the underlying fat layer as well as the short flexor muscles of the foot are used to cover the stump and that scars are located on the stretching side, i.e. on the back of the foot, outside the stress zone, as otherwise painful pressure points can develop. In diabetic foot syndrome with necrosis (gangrene) or diabetic microangiopathy (disease of the smaller vessels), border zone amputations are performed, which can be delimited along anatomically defined lines on the metatarsus.
In the case of amputations of the lower leg, the entire tibia (tibia) and fibula can usually be retained and a separation can be made just above the ankle joint (syme amputation), but this residual limb is difficult to treat prosthetically and cannot always bear weight without restrictions. In contrast, amputation is more frequently performed in the area between the upper third of the lower leg and the middle third of the lower leg. The residual limb can be treated by myoplasty, i.e. the muscles that function as antagonists are connected around the end of the bone.
However, a muscle skin flap folded from the back (dorsal) to the front (ventral) is also capable of supplying the residual limb. The disarticulation of the knee joint, which was previously rejected because of its sparse limb coverage without muscles, is now increasingly performed in PAVK (peripheral arterial occlusive disease) patients. This is because the advantages lie precisely in the length of the residual limb (lever arm) and the strength (preserved thigh muscles).
For vascular patients, the amputation height depends on the blood supply to the muscles. It is therefore possible that a thigh amputation may also have to be performed. The optimal height for this is in the middle of the thigh bone.
The bone stump must be shortened considerably in relation to the skin soft tissue mantle so that the opposing (antagonistic) muscles can be sutured over the thigh bone (femur). In this so-called myoplasty, the muscles must first be fixed to the bone (myodesis), after which they can be sutured together. This maintains good muscle tension and activity and ensures good padding.
The danger of neurombiological formation is particularly present in the nerve supplying the thigh (sciatic nerve), which must therefore be prevented (ligated) far above the amputation site. A hip joint disarticulation is a much more difficult procedure with a large soft tissue wound and high mortality (death of the patient). It should only be performed in the case of the most severe infections or tumours.