Abstract
Introduction
Lower limb amputations are common in conditions of progressive dysvascular disease on its own or in combination with diabetes. These patients have to cope with increased frequency of inherent cardiac and cerebral co-morbidities and additionally sequelae related to the amputation/limb loss. The residual limb/stump issues, surviving leg issues and systemic problems lead to a ‘post amputation syndrome’ picture. The rehabilitation team needs to be aware of and address these issues, albeit within their limitations; thus encouraging improved mobility and independence.
Post amputation syndrome – does it exist?
The sequelae subsequent to lower limb amputations are quite specific and result from the amputation/limb loss, associated co-morbidities, limited exercise tolerance and impaired mobility status.
The causation of lower limb amputations in the UK has changed in the last 70 years, from trauma, subsequent to the Second World War, to dysvascularity as the main causation factor. Dysvascularity related to Peripheral Vascular Disease (PVD) and Diabetes is now noted to be the most common cause of lower limb amputation in the UK. 2005–2006 data from National Amputee Statistical Database Group (NASDAB) indicates that dysvascularity is the cause of lower limb amputation in 75% of presentations.
By rough estimates there are approximately 50,000 lower limb amputees in the UK and the recent NASDAB data indicates that, 5000 amputees were referred to Disablement Services Centres (DSC) for prosthetic/amputee rehabilitation in 2005–2006; 50% were over 65 years of age, and 25% of these were over 75 years of age. The median age for males was noted to be 66 years and for females 69 years. 91% of all amputee referrals were for lower limb amputations, 5% for upper limb amputations, 4% were in the congenital/other causes group.1
Discussion
As the causation is mainly dysvascularity in the lower limb amputees, these patients do have significant co-morbidities of associated impairment of their cardiac, cerebral, respiratory and musculo-skeletal systems, with the added compounding factor of overall decreased survival rates as compared to the normal cohort. Against this backdrop, the lower limb amputees have a ‘double whammy’ in the nature that, they have many sequelae related to the amputation itself, leading to a ‘post amputation syndrome’ type of picture. Currently in the UK, most amputees are referred to supra-district or sub-regional Disablement Services Centres, which receive these tertiary referrals from various vascular/diabetic/trauma units.
In amputee rehabilitation medicine, an amputee is noted to be established one year following the amputation, and a lower limb amputation is considered to be major amputation if it is proximal to ankle disarticulation level.
Our description of post amputation syndrome picture can be sub-divided into three relevant areas: Amputation stump-related issues; Surviving leg-related issues; Other systemic issues.
(a) Amputation stump-related issues
Problems with healing. The stump-related issues are mainly of delayed healing and non-healing of the stumps related to dysvascularity, along with episodic breakdown of incisional areas. Approximately one third of the stumps are unhealed at initial six weeks post amputation assessment.
Phantom limb phenomena. Previous studies have indicated that, phantom limb pain is present in between 10 and 90% of the amputee population. Seminal work by Sherman et al. noted that this is present in about 50–75% of patients. Our study indicated 85% occurrence.2,, 3 Most treatment modalities in the established amputee are on a conservative basis, after ruling out extrinsic or infective causes of pain.
Skin disorders in amputees are well known.
Studies indicate that a third of amputees experience a skin problem. Lesions resulting from friction, pressure and occlusion are common, leading to folliculitis and epidermoid cysts. Allergic contact dermatitis (ACD) is seen in a third of patients with stump dermatitis. These patients do benefit by patch testing and avoidance of aggravating stump socket interface materials.4
(b) Surviving leg-related issues
A key prognostic indicator of successful prosthetic rehabilitation of the lower limb amputee is the state of the surviving leg. In addition to its initial state following the amputation, the surviving leg is more prone to wear and tear as compared to its pre-amputation status.
Osteoarthritis in proximal and contralateral joints. There is increased frequency of osteoarthritis both on the surviving leg side and the ispilateral amputated side in lower limb amputees, as compared to normal population. Our study indicated that there is increased frequency of osteoarthritis in the proximal hip joints on both the amputated side and non-amputated hip side. There was a three-fold increase in the risk of osteoarthritis for patients with above knee amputation as compared to below knee with additional significant localized osteopenia in the remnant bone in the amputated stump.5
Increased vulnerability of the surviving foot, especially in diabetic dysvascular amputees. These patients are 15 times more vulnerable to foot ulcers as compared to a normal cohort.6
Excess energy expenditure. Subsequent to a major lower limb amputation, there are increased energy expenditure requirements on ambulation. Dysvascular below knee amputees expend approximately 25% more energy than normal cohorts, whilst above knee amputees can expend up to 60% more energy as compared to normal matched cohorts. This limits the walking distance, and with associated co-morbidities of impaired cardio-respiratory function, further limits their ambulation potential.7,, 8
Gait abnormalities. These are more common in transfemoral amputees. The common features are of decreased cadence, stride length and speed, and an increase in ground reaction forces and centre of pressure in the foot of the surviving leg.8
(c) Other systemic issues
Falls. There is increased frequency of falls in the major lower limb amputees. Studies have indicated that 58% of unilateral amputees and 27% of bilateral amputees sustained at least one fall in the previous 12 months of which 7% sustained bony injuries. Some 12% were related to prosthetic causation alone, 22% related to the environment and 48% were as a result of intrinsic patient-related factors. Hence the lower limb amputees are vulnerable to falls leading to bruising of the stump, with resulting inability to wear the prosthesis, and also leading to loss of confidence and increased dependency.9
Low back pain. Whilst there is about 30% prevalence of back pain in the general population, in the lower limb amputee cohort, there is significant increased frequency of low back ache (LBP). Our study indicated 81% frequency of low back pain in the above knee amputee cohort and 62% in the below knee amputee cohort. Hence there is more than twice the frequency of low back pain in the major lower limb amputees as compared to the normal cohort. LBP is related to biomechanical (myofascial) components rather than degenerative causes.10
Incomplete body image issues/psychological impairment. Although a considerable number of the dysvascular lower limb amputees are to some extent settled by the fact that they have got rid of their liable painful/ulcerated leg, they still undergo psychological impairment related to incomplete body image and benefit by access to counselling.
Work/social issues/handicaps leading to limitation in participation. Major lower limb amputees have limitations in their work potential and hobbies and do need appropriate ergonomic advice and assessment for suitable adaptations. The majority do restart driving after informing the Driving Vehicle Licensing Authority and the completion of suitable modifications to their car.
Decreased life expectancy. Dysvascular lower limb amputees have decreased life expectancy because of compounding co-morbid issues. The median survival of dysvascular lower limb amputees is four years and the diabetic cohort has a poorer prognosis than the PVD cohort. The hazard ratio is noted to be twice as much in the diabetic cohort as compared to the non diabetic PVD cohort. Overall, the 10-year survival rates range from 27–57% with the median survival being four years.11
Conclusion
In our opinion the sequelae following lower limb amputation do lead to a compounding ‘post amputation syndrome’ type of picture. It is imperative that the amputee/prosthetic rehabilitation teams are aware of these issues and prevent the avoidable elements. The way forward would be to have an integrated care pathway, from the time of admission to the vascular unit to post amputation comprehensive rehabilitation via a multidisciplinary team, and an ongoing lifelong follow-up in a comprehensive amputee rehabilitation centre facility.