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.

Weight transfer can be achieved indirectly by allowing pressure through a bony point higher up the leg and also by effecting force transfer through the sides of the leg tissues. There may often be a pain issue after this procedure despite modern prosthetic accomplishments and if the pain is significant it can lead to limited use of the prosthesis, functional reduction and eventually to further attempts at surgery.

Other reasons for amputation are less common and include tumours, infections and congenital abnormalities of the lower limbs. Overall amputation is considered an operation which involves reconstruction rather than just removal of a limb, as the patient’s future life and independence is the crucial matter. The higher that the surgeon has to amputate the limb the higher levels of energy are needed for walking, with the speed of walking decreasing and the required oxygen consumption increasing. Low below knee amputation may make little difference to the energy required for gait, however once the level moves up to mid thigh the load may be over 50% more.

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, physiotherapy, physiotherapist in northampton, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.