Lower Limb Amputation - Part Two
Patients for amputation do not usually present diagnostic difficulties as they are mostly referred with a history of peripheral vascular disease and extensive treatment. The gradual blocking off of the minor blood vessels causes gangrene in the toes and ulcers on the areas which suffer pressure. This is followed by invasion by bacteria which leads to soft tissue infection and then to infection of the bone. Treatment can be long and drawn out with repeated operations and attempts at lesser amputations, leading to a long period where the patient is non-functioning and in pain.
In traumatic injuries the patient may suffer a traumatic amputation or a severe compound fracture with concomitant vascular and nerve injuries which are beyond repair. An amputation in this case may make good sense rather than trying to salvage a severely damaged limb over a long time. If the limb is salvaged it may not be functional and be a source of significant pain which may be depressing for the patient and less useful than having an artificial limb. At some stage after the injury a decision needs to be made if the long period of treatment and non-function is worth it for the end result as compared to an amputation.
The overall goal of amputation is to maintain the length of the limb and preserve the greatest degree of functional use from the leg. As amputation is irreversible the decision has to be correct but the only restrictions are the patient''s ability to withstand an operation. As the abnormal limb may be the main factor maintaining the unwell medical status of the patient then amputation can be seen as a way to restore medical balance and in many cases to save a patient''s life. Pre-operative preparation involves a multidisciplinary team to assess the physical, social and psychological aspects of the patient''s condition to prepare them for future changes.
Surgical management of severe leg trauma has shown significant advances in the ability to perform microsurgery to the vascular structures, advanced fixation of fractures and techniques to promote revascularisation of tissues. Amputation may then be viewed as a failure if these techniques cannot save the limb, but viewing it as a reconstructive process is more positive, allowing an increase in useful functional capacity. Techniques of amputation have seen much less development and patients still consult with difficulties such as persisting pain, swelling, limited use of the prosthetic limb and feelings of instability.
During surgery the surgeons are careful to keep a good skin length so it can be folded across the remaining limb and not with significant tension, position muscle over the bone end and perhaps stitch opposite muscle groups together and cut the nerves when they are tensioned to some degree and position their cuts away from the limb end so they do not suffer future tension. A general rule for planning the length of the remaining limb is to give 2.5cm of length for every thirty cm of the person''s height. After the operation the wound is dressed and post operative analgesia given.
Once the patient has got over their immediate post-operative period they will be seen by the physiotherapist who will check their respiratory status, teach them positional exercises, encourage upper body exercise and assist with safe transfers and early ambulation as appropriate. After perhaps two weeks the physiotherapist may move on to muscle exercises of the extremity itself and may initiate desensitisation of the remaining limb. This reduces the sensitivity of the area so it is prepared for its job with weight bearing inside a prosthesis.
Around six weeks after the operation the state of the wound may permit the start of the planning period for wearing the prosthesis although some patients will never manage one because of impaired balance, muscle weakness or lack of understanding. There are many other potential complications to having an amputation which may interfere with restoring the patient to their maximum independence. There may be breakdown of the wound as healing is poor in patients with peripheral vascular disease, skin problems, swelling of the area, contractures of the nearby joints, pain and phantom limb pain and sensations.