Lower Limb Amputation
Lower limb amputation is a major undertaking and greatly affects the life of the individual, adding psychological stresses to the physical efforts of rehabilitation, fitting for a new limb and learning the skills of walking again. The surgeon will plan the process so that the patient can manage the prosthesis easily, participate as soon as possible in rehabilitation and expend the lowest levels of energy in gait. The patient has to learn a large number of new skills - putting the prosthesis on and taking it off, monitoring the skin for areas of excessive pressure, walking on even and uneven surfaces and getting around when they are not wearing the artificial limb.
To manage all these skills and learn how to be as independent as possible the patients need a skilled team to manage them which includes their own doctor, the surgeon, a physiotherapist, an occupational therapist a prosthetist and perhaps an employment adviser. The number of lower limb amputations is likely to continue to rise as the elderly populations increase in more advanced industrialised countries, with ischaemic vessel disease the primary cause. The proportion of above knee to below knee amputations has changed as surgeons became more skilled at preserving the knee joint so that the present ratio is 30% above knee to 70% below knee.
Peripheral vascular disease (PVD) is the most common reason for amputation with a significant number of patients suffering an amputation on the other side within three years. Most patients are elderly and have ischaemic problems which are secondary to diabetes, with peripheral neuropathy a common difficulty which can lead to ulcers and gangrenous changes. Trauma to the lower limb which involves the arteries and nerves can be treated but may result in a leg which is painful and does not function well, meaning that an amputation would be preferable for speedy rehabilitation and return to normality.
Less often amputation is performed for other conditions such as congenital lower limb abnormalities, infections and tumours. Amputation should be planned as an operation which is aimed at reconstruction rather than just removing a part, as the most important matter is the future function and independence of the patient. As the amputation is performed higher and higher in the limb so the speed of gait reduces, the oxygen consumption requirements increase and the overall energy requirements rise for the work of walking. There may be little increase in energy needed for below knee amputation, but 50% or more for mid thigh amputation.
The energy requirements for gait are extremely important as amputated patients frequently suffer from ischaemic tissue problems or other medical conditions which lead to walking consuming much of their energy abilities. Independence in functional activities may be hard to achieve as much of their limited energy supplies is taken up with simply walking. After the amputation, due to the skin viability and ischaemic diagnosis, healing may be delayed and this can have an important bearing on the eventual outcome for the patient''s independence. The soft tissues at the site of amputation must act as the connecting point between the leg and the prosthesis.
Allowing a bony area higher up to take some of the weight transfer indirectly can be successfully integrated with weight transfer sideways through the soft tissues of the lower leg. There may still be pain issues for patients despite the many advances made in modern prosthetics. Significant pain can lead to a reduction in function, reduced use of the prosthesis and even to further surgery.
More indirect weight transfer can be accomplished by allowing a higher bony area to take some of the force with other forces being transferred across the sides of the soft tissues of the leg. Pain may still be an issue for many patients despite the great advances made in prosthetic technology. If the pain is severe enough it can lead to further surgery, reduced function and limited wearing of the artificial limb.