Amputation of the Lower Limb
The amputation of a leg is a major happening for a person and represents an upheaval in their life, with psychological problems added to the difficulties of learning the rehabilitation, the management of the new prosthesis, and the relearning of ambulation. The surgeon’s plan will be to manage the process to allow the patient early access to rehabilitation, reduce their energy requirements in walking to the minimum and allow them to manage the prosthesis successfully. Many new skills have to be learnt such as mobilising without the new limb, checking the skin pressure areas and managing to get the limb on and off.
A skilled and experienced team is required to teach the patient all the knowledge and skills they need for maximum independence and this includes the surgeon and his team, the medical advisers, the prosthetist, an occupational therapist, the physiotherapist and employment and social facilitators. Lower limb amputations are increasing as the populations of industrialised countries continue to age and with that the main reason for amputation, peripheral vascular disease. The ratio of below knee amputations to above knee amputations has changed as surgical skills for keeping the knee joint have increased, leading to the present occurrence of 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.
Amputation is also employed for less common conditions such as infections, congenital lower leg abnormalities and tumours. The planning for an amputation should be viewed as an operation targeted at reconstruction and not just removing a body part, aiming for the planned independence and function of the patient. As the level of the amputation progresses up the leg this increases the work of walking, requiring increased levels of oxygen concentration, increased expenditure of energy levels and reducing the speed the person is able to walk. Below knee amputation shows little increase in energy needed for walking but mid thigh can increase this by fifty percent.
The energy load of walking may be very important as many patients who undergo amputation suffer from peripheral vascular disease and may have other medical disorders, all meaning that much of their reduced energy may be consumed in walking. This means that getting sufficient strength and walking ability to attain functional independence may be difficult. Healing after amputation is not a foregone conclusion due to the likely reason for the operation being poor circulation, and the condition of the skin exerts an important influence over the overall functional outcome for the patient. The soft tissues around the amputation site function as the connection between the prosthesis and the leg.
To be able to walk effectively the soft tissues of the amputation stump must be large and of good enough quality to cope with the longitudinal and shearing stresses which will occur in its relationship with the socket of the prosthesis. The end of the limb can directly bear weight in a longitudinal manner in some amputations such as through the ankle or through the knee, although these through joint amputations could be difficult. The new joint in the knee in this case is below the original and this makes the knee stick out further than the original and the calf region much shorter than normal.
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.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapy, back pain, orthopaedic conditions, neck pain, injury management and physiotherapists in Reading. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.