Ramesh Munjal and Gillian Atkinson

Introduction

For some patients with lower limb ischaemia, amputation may be the only interventional option because revascularisation is not possible, has failed or the leg is unsalvageable. Amputation may also be a better option than complex revascularisation when patients are bed-bound and/or demented. Amputation should not be regarded as ‘failure’ of treatment but should be seen by patients as well as clinicians as a positive procedure. Amputation should aim to relieve pain, remove dead, severely ischaemic or infected tissue, and improve quality of life. This is true even for those who may not be able to walk with a prosthesis.

The planning and process of rehabilitation for amputees should start prior to amputation and continue into the community. Expert and holistic assessment of the patient leading to careful selection of the level of amputation, good surgical technique and optimal postoperative management are all vital in the initial stage of amputee rehabilitation. The process then dovetails into postamputation early rehabilitation, e.g. use of early walking aids, wheelchair and home assessments, prosthetic rehabilitation where appropriate, and continuing follow-up and support to patients and their families in the community.

This chapter concentrates on the rehabilitation of patients undergoing amputation because of lower limb ischaemia, although the principles involved are similar for amputations due to other causes, such as trauma.

Epidemiology

Peripheral arterial occlusive disease accounts for the vast majority of lower limb amputations in westernised societies. More than 80% of all amputations carried out in the UK are due to vascular disease but an increasing proportion have diabetes mellitus.¹ The overall risk of amputation is six times higher in insulin-dependent people with diabetes compared with non-insulin-dependent people with diabetes. A global study group also reported a marked difference in the incidence of amputation between 10 centres in six different countries. Rates were highest in the North American and northern European centres and lowest in Spain, Taiwan and Japan. In the Navajo population, a very high prevalence of diabetes was thought to be the explanation for their high amputation rates.²

The National Amputee Statistical Database for the UK reported that dysvascularity is the most common reason for referral to prosthetic services centres following a lower limb amputation, accounting for 70% of all lower limb referrals in 2006–7.³ In this group referred to the prosthetic centres in the UK, 53% were transtibial and 39% were transfemoral amputees. In this 1-year period there were a total of 4957 referrals to Prosthetic Services in the UK, of which 4574 were following lower limb amputation (92% of the total).³

There is some evidence that the impact of modern vascular surgery may reduce the incidence of amputation.⁴ The Danish National Amputation Register has demonstrated a 27% fall in the number of major amputations due to peripheral vascular disease in the decade 1980–90. This decline was attributed to the increased use of infrainguinal bypass operations.⁵ A paper from Finland also reported that it was possible to reduce amputation rates with an aggressive reconstruction policy in critical limb ischaemia.⁶ However, the West Coast Vascular Surgeons Study Group in Sweden failed to demonstrate a negative correlation between amputation and revascularisation rates.⁷

Survival rates after an amputation depend upon the cause of the amputation rather than the amputation itself. Those who have amputations following trauma tend to have good long-term survival, but those from vascular disease (including diabetes) face a 30-day mortality rate reported to be between 9% and 15% and a long-term survival rate of 60% at 1 year, 42% at 3 years and 35–45% at 5 years.⁸ Of people with diabetes who have lower limb amputation, up to 55% will require amputation of the second leg within 2–3 years.⁹

Indications for amputation

The decision to perform amputation seems straightforward where there is extensive tissue loss or no reasonable prospect of revascularisation. However, the precise role of amputation in the management of critical limb ischaemia remains controversial. If it is predicted that vascular reconstruction is likely to be unsuccessful, then primary amputation perhaps offers the best outcome in terms of quality of life and cost benefit.¹⁰ Chapter 3 discusses the treatment of chronic lower limb ischaemia and covers these issues of economics and quality of life in more detail. Where patients with critical limb ischaemia also have coexisting disabilities or other medical conditions that would render them unable to make use of a salvageable limb, then primary amputation with appropriate rehabilitation offers the best option. Examples of such patients include those with severe dementia, dense hemiplegia or spinal paralysis, severe arthritis and severe cardiorespiratory disease.

Level selection

Selection of the ideal level of amputation depends on the healing potential, rehabilitation potential and prosthetic considerations. The potential for rehabilitation and likely goals can only be set by a holistic assessment of the patient by the specialist amputee rehabilitation team. This assessment should include other illnesses and disabilities, cognitive state and motivation, likely discharge destination, lifestyle, as well as the patient’s own aspirations and wishes.

In general terms, the more proximal the level of amputation, the more difficult it will be for the patient to achieve independent walking. Therefore, the more distal the amputation site, the better the rehabilitation potential for walking, as this preserves more joints and hence more control of the prosthesis. Figure 6.1 is an algorithm dealing with level selection.

Except in people with diabetes with good foot pulses (see Chapter 7), local amputation of single or multiple toes generally does not heal unless the foot can be revascularised. Transmetatarsal or ray amputation, if technically feasible, produces excellent functional results. Chopart’s mid-tarsal amputation and Symes’ through-ankle amputation are rare in chronic limb ischaemia and are not recommended because of the risks of developing an equinus deformity (in Chopart’s), movement of the distal flap (in Symes’), poor long-term flap viability and considerable technical difficulties in prosthetic fitting. Thus, the commonest major levels of amputation in limb ischaemia are transtibial, knee disarticulation, Gritti–Stokes and transfemoral. Hip disarticulation and hindquarter amputation are rare and in 2006–7 accounted for just over 1% of all cases of lower limb amputations referred to the prosthetic centres in the UK. Dysvascularity was given as the cause for this level of amputation in only 19% of cases.³ In our experience this level of amputation is mainly considered for people with neoplasia (usually sarcoma) or intravenous drug users (IVDUs). Preservation of the knee joint has enormous advantages in terms of mobility. In one study, 80% of transtibial amputees achieved unlimited household mobility or better, compared with 40% of above-knee amputees.¹¹ In a Sheffield study, only 26% of transfemoral vascular amputees achieved community ambulation, compared with 50% of transtibial vascular amputees at 1-year follow-up of a group of amputees who underwent prosthetic rehabilitation. In this study group, the figures for household mobility were 48% and 63%, respectively, for transfemoral and transtibial vascular amputees at 1-year follow-up.¹²

Transcutaneous oximetry (tcP_O2),¹³ photoplethysmography,¹⁴ laser Doppler velocimetry,¹⁵ thermography¹⁶ and isotope clearance rates¹⁷ have all been shown to correlate with subsequent stump healing. However, while all these methods seem superior to Doppler ankle pressures,¹⁸ a review concluded that sensitivities and specificities were inadequate to recommend their clinical use.¹⁹

The energy cost of walking with prostheses for vascular amputees is increased by 63% and 117%, respectively, in unilateral transtibial and transfemoral amputees compared with non-amputees. In bilateral transfemoral amputees, it is calculated that energy cost is 280% higher.²⁰ Therefore, it should not seem surprising that even in a selected group of bilateral transfemoral amputees who were successfully trained to walk with prostheses in an inpatient rehabilitation facility, the majority of them abandoned walking when they returned home and preferred to be wheelchair-dependent.²¹

Thus, for patients in whom major lower limb amputations are necessary, the following points should be remembered:

Surgical considerations

All amputations should be carried out by surgeons experienced in the procedure and should not be delegated to unsupervised and inexperienced junior staff. The following important general principles should be followed: