Selection of amputation level: a review

The Role of Cutaneous Microcirculatory Responses in Tissue Injury, Inflammation and Repair at the Foot in Diabetes

Diabetic foot syndrome is one of the most costly complications of diabetes. Damage to the soft tissue structure is one of the primary causes of diabetic foot ulcers and most of the current literature focuses on factors such as neuropathy and excessive load. Although the role of blood supply has been reported in the context of macro-circulation, soft tissue damage and its healing in the context of skin microcirculation have not been adequately investigated. Previous research suggested that certain microcirculatory responses protect the skin and their impairment may contribute to increased risk for occlusive and ischemic injuries to the foot. The purpose of this narrative review was to explore and establish the possible link between impairment in skin perfusion and the chain of events that leads to ulceration, considering the interaction with other more established ulceration factors. This review highlights some of the key skin microcirculatory functions in response to various stimuli. The microcirculatory responses observed in the form of altered skin blood flow are divided into three categories based on the type of stimuli including occlusion, pressure and temperature. Studies on the three categories were reviewed including: the microcirculatory response to occlusive ischemia or Post-Occlusive Reactive Hyperaemia (PORH); the microcirculatory response to locally applied pressure such as Pressure-Induced Vasodilation (PIV); and the interplay between microcirculation and skin temperature and the microcirculatory responses to thermal stimuli such as reduced/increased blood flow due to cooling/heating. This review highlights how microcirculatory responses protect the skin and the plantar soft tissues and their plausible dysfunction in people with diabetes. Whilst discussing the link between impairment in skin perfusion as a result of altered microcirculatory response, the review describes the chain of events that leads to ulceration. A thorough understanding of the microcirculatory function and its impaired reactive mechanisms is provided, which allows an understanding of the interaction between functional disturbances of microcirculation and other more established factors for foot ulceration.

Prediction of stump healing in lower limb amputation: a narrative review

Both types of diabetes, as well as different forms of acquired diabetes, are associated with diabetic peripheral neuropathy. Diabetic foot ulcers (DFU) is the condition most commonly related to somatic peripheral neuropathy, often leading to gangrene and limb amputation. Independent from large-vessel disease, sensory loss may result in DFU development and even amputation. The crucial part of any lower limb amputation is the stump healing process, which represents the central goal of postoperative management. Despite the importance attributed to this process, a standard set of guidelines regarding efficient healing methods is yet to be formulated. Health professionals are faced with the challenge of assessing the different risk factors and deciding which has a greater influence on the stump healing rate. There is currently an insufficient number of studies regarding factors effecting lower limb amputation. The main purpose of this review is to discuss the markers that can be helpful in the prediction of stump healing in patients who have undergone lower limb amputation.

REVIEW: HEMODYNAMIC STUDIES FOR LOWER LIMB AMPUTATION AND REHABILITATION

No matter what the reason and level of amputation are, amputees will face many complex postoperative problems and potential complications. From the perioperative stage to lengthy rehabilitation process, patients need comprehensive and cautious therapies to help them rebuild their physical and mental health. Although there is some scattered information, the achievements of hemodynamic study for lower limb amputation and rehabilitation have not been systematically classified and summarized. The purpose of this review is to introduce and discuss the hemodynamic issues in preoperative diagnosis, surgical techniques and postoperative problems in the past two decades. Whether from clinical or biomechanical perspective, the investigations of the former two stages have been relatively mature and gained some clear outcomes, even if some conclusions are conflicting and controversial. While in terms of the postoperative problems, such as the common pressure ulcers, DTI and muscle atrophy, there is a lack of vascular or blood flow state studies specifically for lower residual limb. Therefore, the future research focus of hemodynamics for lower limb amputation should probably be the detailed investigations on the relationships between various blood flow parameters and certain common complications. Although hemodynamic research has made some achievements at this stage, it is believed that more advanced and reliable techniques are pending for further explorations and developments.

Epidemiological study of lower limb amputation in England between 2003 and 2008

BACKGROUND

The purpose of this study was to investigate the prevalence of lower extremity amputation in England, to establish the associated mortality, and to determine the relationship with diabetes mellitus and previous revascularization.

METHODS

Data on all patients who had a lower extremity amputation between 2003 and 2008 were extracted from the Hospital Episode Statistics database. Risk adjustment and linear regression were used to compare the data.

RESULTS

The major amputation rate was 5.1 per 100,000 population and did not change over the 5 years. The mortality rate for major leg amputation was 16.8 per cent (21.4 per cent for above-knee and 11.6 per cent for below-knee amputation); this decreased significantly over time (P < 0.001). There was a significant difference in amputation rate, mortality rate and the below-knee : above-knee amputation ratio between different areas of England (P < 0.001). Some 39.4 per cent of patients who underwent major amputation had diabetes mellitus. The odds of revascularization before amputation increased significantly over time (P = 0.035).

CONCLUSION

Major and minor amputation rates were stable across England between 2003 and 2008, accompanied by a significant reduction in perioperative mortality. There were significant geographical variations in amputation rates, mortality rates and the below-knee : above-knee amputation ratio.

[Stump retention and extension on the lower extremity]

Despite new techniques and better health programs in western industrialized nations, the numbers of amputations on the lower extremity remain constant. Approximately 100,000 amputations are performed annually in the U.S. and about 10,000 in Germany, more than 90% for gangrene resulting from ischemia and/or infection. Micro- and macroangiopathic changes in diabetes are the major cause of ischemia in the leg. The preservation of limb length and construction of an end bearing stump are important criteria for the functional outcome after amputation. Especially in trauma and tumor patients with "planned" amputations, all effort should be made to achieve an end bearing stump with sufficient length respectively an amputation level that is suitable for orthosis instead of prosthetic supplementation. After amputation, an interdisciplinary approach is mandatory to achieve sufficient soft tissue coverage or stump distalization. In case of insufficient bearing ability of the stump, various reconstructive possibilities must be considered to assure optimal outcome.

When is a more proximal amputation needed?

Amputation may be the most appropriate therapy for an ischemic or infected limb, but the level at which to amputate is often difficult to determine. Selecting the appropriate level is crucial when performing an amputation. The goals of surgery are to maintain maximal limb length and ensure successful healing. When more of the foot and limb can be preserved, the chances for rehabilitation are improved. This article reviews how to determine the most appropriate level of amputation.

Stump management after trans-tibial amputation: a systematic review

In order to achieve stump healing after trans-tibial amputation, various methods are applied, such as soft dressings followed by elastic wrapping of the stump, rigid dressings, semi-rigid dressings, and more recently the application of silicon or gel-liners. A systematic literature search was performed to identify the optimal post-amputation management. The methodological quality of the studies was systematically evaluated by using a predefined list of criteria. Only 11 controlled studies were identified and evaluated for their methodological quality. From these studies, no studies were classified as A-level studies, whereas three were classified as B-level, and 8 were classified as C-level studies. Relevant literature appears heterogeneous with respect to patient selection, intervention and outcome measures. Despite the large variability of included studies, this review reveals a trend in favour of rigid and semi-rigid dressings for achieving stump healing and reduction of stump volume. No conclusions can be drawn with regard to the effect on functional outcome. The literature is not conclusive on the effects of early weight bearing on stump healing, volume reduction, and functional outcome. More research is needed for the development of evidence-based clinical practice guidelines concerning management after transtibial amputation.

[Electrical stimulation for rapid assessment of extremity tissues vitality in critical ischemia]

INTRODUCTION

In cases of trauma of the extremities, the development of critical tissue ischemia is a frequent complication, requiring surgical intervention with possible amputation. The exact duration of blood supply loss is often difficult to evaluate. Therefore, an easily applicable simple and rapid method for tissues vitality assessment would be of appreciable importance. It could also be used during surgery for delimitation of viable from non-viable tissue.

METHOD

The well-known approach for nerve-muscle excitability assessment by electrical stimulation is adopted. Its simplest form is by visual observation of the tissue reaction to the respective excitation. A battery supplied electrical stimulator is built for this purpose, housed in two hand-held electrode holders. The stimuli parameters were selected for efficient excitation of denervated and partially denervated tissue structures.

RESULTS

The stimulator was used in assessment of the condition of 23 patients: 16 with severe critical arterial ischemia from arterial occlusive disease and seven with vessel trauma and injuries. Eight extremities were tested immediately after amputation.

CONCLUSION

The stimulator was shown to be very efficient for tissue vitality assessment in the diagnostic stage. The easiness of use makes it convenient for application in the ambulatory, during transportation, at the patient bedside, as well as during surgery. It can also be efficient in mass accidents, disasters, or in armed conflicts.

Laser Doppler Skin Perfusion Pressure in the Assessment of Raynaud's Phenomenon

OBJECTIVES

In the assessment of Raynaud's phenomenon, objective evaluation of digital microcirculatory flow is important, and so we investigated whether the measurement of laser Doppler skin perfusion pressure could be of use.

MATERIALS AND METHODS

Ten fingers of five patients with secondary Raynaud's phenomenon due to systemic sclerosis, 22 fingers of 11 patients with primary Raynaud's phenomenon and 10 fingers of five control patients were examined. Skin perfusion pressure was measured on the third finger of both hands at rest, and then again 3 min after local cold exposure.

RESULTS

Laser Doppler skin perfusion pressure at rest in patients with secondary Raynaud's phenomenon was significantly lower than that in patients with primary Raynaud's phenomenon and the control patients (p<0.05). Skin perfusion pressure decreased significantly in both patient groups upon local cold exposure (p=0.005). There were significant differences in perfusion pressure after cold exposure among both groups (p<0.05).

CONCLUSIONS

The low skin perfusion pressure at rest in patients with secondary Raynaud's phenomenon suggested the presence of obstructive arterial lesions. The marked pressure decrease in all Raynaud's patients after local cold exposure might be due to vasospasm of the microvasculature in the digits. These results indicate that the measurement of laser Doppler skin perfusion pressure is valuable in the diagnosis of Raynaud's phenomenon.

A comparison of laser Doppler fluxmetry and transcutaneous oxygen pressure measurement in the dysvascular patient requiring amputation

OBJECTIVE

To determine the predictive power of laser Doppler fluxmetry (LDF), both heated and unheated, as a preoperative investigation of wound healing potential in dysvascular patients requiring amputation, by comparison with transcutaneous oxygen pressure measurement (TcpO2) and the limb to chest TcpO2 index.

METHODS

Thirty-five non-diabetic patients with peripheral vascular disease were investigated before amputation. Heated and unheated LDF and heated TcpO2 measurements were taken on the chest wall and at the routine above-knee, below-knee and mid-foot amputation levels. Wound healing potential was evaluated against a TcpO2 index value of 0.55 and on clinical outcome.

RESULTS

A heated LDF value of 4.9 arbitrary units (au) was shown by receiver-operator characteristic curve to have the best predictive power, with an overall accuracy for preoperative prediction of wound healing of 91.4%, and a predictive value for wound failure of 89%. Based on the heated LDF of 4.9 au, review of 26 amputations performed shows the overall accuracy for preoperative prediction of wound healing of 92.3%, a predictive value for wound healing of 100%, and a predictive value for wound failure of 62.5%.

CONCLUSION

A heated LDF value of 4.9 au appears to be a useful predictor of the potential of an amputation site to heal.

The concept of knee salvage: why does a failed femorocrural/pedal arterial bypass not affect the amputation level?

OBJECTIVES

There is continued controversy over whether a failed distal bypass influences the level of amputation. This issue is important as the number of arterial bypass grafts undertaken for critical ischaemia is increasing, followed by an increasing number of failed grafts.

SETTING

Teaching hospital. STUDY DESIGN AND MATERIALS: A prospective analysis of 109 consecutive femorocrural/pedal bypass grafts performed between June 1991 and January 1995 on patients presenting with severe critical lower limb ischaemia (CLI) to a single vascular unit. A further 43 amputations for non-reconstructible distal disease were also analysed.

CHIEF OUTCOME MEASURES

Mortality, amputation, rehabilitation, survival and knee salvage rates. The Kaplan-Meier method was used for comparison of factors associated with knee preservation.

RESULTS

Primary amputees had a higher in-hospital mortality (18% vs. 10%) but similar 3 year survival rates (30%) compared with secondary amputees (36.6%). Patients with successful grafts showed a trend towards better survival (61.9% at 3 years) compared to amputees (38.6% at 42 months, p = 0.061). Below- to above-knee amputation ratio was similar in the two groups (0.85 in secondary vs. 0.95 in primary amputees). Factors significantly associated with knee salvage at 3 years were shown to be: the condition of the inflow (81.9% for good vs. 43.1% for impaired, p = 0.000) the state of the profunda femoris artery (good 93%, impaired 71%, occluded 37% p = 0.0001) and the graft material (vein 81.8% vs. PTFE 59.8%, p = 0.033). The presence of tissue loss (p = 0.0523) and secondary procedures (p = 0.0879) showed a trend to become significant. Multivariate and Cox regression analysis showed that the most important factors were the inflow (p = 0.001), the state of the profunda (p = 0.001), the graft material (p = 0.034) and previous revascularisation attempts (p = 0.019).

CONCLUSIONS

The factors which determine knee loss are a compromised inflow state, the presence of an inadequate profunda femoris, previous revascularisation attempts and the use of synthetic graft material. Most of these factors (with the exception of infection related to revascularisation) are present before reconstructive arterial surgery is performed and this study shows that failure of a distal graft does not affect the final amputation level.

Simultaneous measurement of digital artery and skin perfusion pressure by the laser Doppler technique in healthy controls and patients with peripheral arterial occlusive disease

OBJECTIVE

To assess feasibility of a new technique for simultaneous measurement of digital artery and skin perfusion pressure at the same digit using the laser Doppler method and to measure the pressure gradient between the two vessel compartments in controls and patients with peripheral arterial occlusive disease.

DESIGN

A pressure cuff wrapped around the basis of the toe and connected to a Statham transducer is covered by a special plastic capsule. A hole at the distal end of the capsule permits positioning of a laser Doppler probe at the pulp. A second laser Doppler probe is placed on the skin beneath the pressure cuff. Reappearance of pulsatile flux during cuff pressure release detected by the two laser Doppler probes indicated digital artery pressure and skin perfusion pressure on the corresponding pressure curve. Results in patients with intermittent claudication were compared to results of a group of normal controls.

SETTING

University Hospital, Zürich, Switzerland.

MATERIALS

Eleven healthy volunteers and 14 patients with intermittent claudication due to peripheral arterial occlusive disease were studied.

CHIEF OUTCOME MEASURES

Digital artery pressure (DAP), skin perfusion pressure (SPP) and pressure gradient between DAP and SPP.

MAIN RESULTS

Significantly lower mean DAP (95.8 +/- 23.2 mmHg vs. 49.8 +/- 20.4 mmHg; p < 0.01) and mean SPP (81.4 +/- 18.8 mmHg vs. 38.4 +/- 21.7 mmHg; p < 0.01) were observed in the patients. Mean pressure gradients and ratios between DAP and SPP did not differ significantly between the two groups. There was a linear correlation between DAP and SPP (r = 0.82, p < 0.01).

CONCLUSION

The laser Doppler method provides the possibility to measure digital artery and skin perfusion pressure simultaneously at the same digit in an easy and non-invasive way. Pressure gradients between DAP and SPP are similar in controls and patients with claudication.

Rehabilitation outcome 5 years after 100 lower-limb amputations

Received wisdom commends a policy of maximizing the ratio of below-knee to above-knee amputations in patients with end-stage arterial disease. After adoption of this policy, the long-term outcome of 100 consecutive lower-limb amputations in 96 patients was monitored by annual review for 5 years. The ratio of primary below-knee to above-knee amputations was 2:1, with 9 per cent of below-knee amputations undergoing revision to a higher level. At 2 years after amputation only 26 per cent of patients were successfully walking out of doors, while 40 per cent had died. By 5 years 67 per cent were dead and only 9 per cent continued to walk out of doors with an artificial limb, although a further 8 per cent continued to use the limb within the confines of their own homes. In a previous audit of 193 amputations performed during the 3.5 years to December 1984, stump healing was a problem in 45 per cent of primary below-knee amputations, compared with 25 per cent in the present study. Although the below- to above-knee ratio in 1984 was only 1:2, the overall rehabilitation rate, as determined by the proportion of patients able to walk at 2 years, was 34 per cent. It is concluded that increasing the proportion of below-knee amputations from one-third to two-thirds of lower-limb amputations for occlusive arterial disease does not improve effective rehabilitation rates. Received wisdom on the desirability of a high below- to above-knee ratio may be wrong.

Prospective study of 713 below-knee amputations for ischaemia and the effect of a prostacyclin analogue on healing. Hawaii Study Group

In 51 hospitals in six European countries 713 patients requiring below-knee amputation for ischaemic disease were studied prospectively. The patients were allocated randomly to receive standard postoperative treatment or standard treatment plus intravenous infusion of the prostacyclin analogue iloprost for 6 h per day over 14-21 days. Healing of the amputation stump and the need for reamputation at a higher level were similar in the two groups. Overall at 3 months 59 per cent of stumps had healed, 19 per cent of patients had required reamputation at a higher level, 11 per cent had died and the remaining 11 per cent remained with unhealed stumps. Preoperative characteristics were analysed as possible risk factors or markers for primary healing, reamputation and death. Previous arterial reopening procedures (surgical or radiological) almost doubled the chances of primary stump healing (P < 0.05). The surgeon's assessment of the likelihood of healing was wrong in 21 per cent of cases in which the operating surgeon thought that healing would probably occur and in 52 per cent of those in which it was thought healing was improbable.

Amputation level is not adversely affected by previous femorodistal bypass surgery

Data was reviewed on patients presenting with lower limb-threatening ischaemia to a single vascular unit between September 1984 and December 1990. Three hundred and thirty patients underwent either femoro-popliteal or femoro-infrapopliteal reconstructive surgery and 316 primary amputations were performed on 281 patients. Sixty-three secondary amputations were performed following a femoro-distal bypass failure. The below-knee amputation to above-knee amputation ratio (BKA/AKA) was 1.0 in the primary amputation group to 0.91 in the secondary amputation group. A direct comparison cannot be made as the patients represent two separate clinical groups. The ratio of reconstructive operations to primary amputations more than doubled between the first and second halves of the study. The BKA:AKA ratio in the secondary amputation group and the total number of secondary amputations remained relatively constant. This study supports the view that previous femoro-distal surgery does not adversely affect the overall outcome of amputation.