A comparison of two diabetic foot ulcer classification systems: the Wagner and the University of Texas wound classification systems

OBJECTIVE

In this study the following two ulcer classification systems were applied to new foot ulcers to compare them as predictors of outcome: the Wagner (grade) and the University of Texas (LT) (grade and stage) wound classification systems.

RESEARCH DESIGN AND METHODS

Ulcer size, appearance, clinical evidence of infection, ischemia, and neuropathy at presentation were recorded, and patients were followed up until healing or for 6 months.

RESULTS

Of 194 patients with new foot ulcers, 67.0% were neuropathic, 26.3% were neuroischemic, 1.0% were ischemic, and 5.7% had no identified underlying factors. Median (interquartile range [IQR]) ulcer size at presentation was 1.5 cm2 (0.6-4.0). Lower-limb amputations were performed for 15% of ulcers, whereas 65% healed [median (IQR) healing time 5 (3-10) weeks] and 16% were not healed at study termination; 4% of patients died. Wagner grade (P < 0.0001), and UT grade (P < 0.0001) and stage (P < 0.001) showed positive trends with increased number of amputations. For UT stage, the risk of amputation increased with infection both alone (odds ratio [OR] = 11.1, P < 0.0001) and in combination with ischemia (OR = 14.7, P < 0.0001), but not significantly with ischemia alone (OR = 4.6, P = 0.09). Healing times were not significantly different for each grade of the Wagner (P = 0.1) or the UT system (P = 0.07), but there was a significant stepwise increase in healing time with each stage of the UT system (P < 0.05), and stage predicted healing (P < 0.05).

CONCLUSIONS

Increasing stage, regardless of grade, is associated with increased risk of amputation and prolonged ulcer healing time. The UT system's inclusion of stage makes it a better predictor of outcome.

The diabetic foot: a global view

It is estimated that approximately 15% of the more than 150 million people with diabetes world-wide will at some stage develop diabetic foot ulceration. Foot problems are indeed a global problem and there is no area in the world that does not report the development of foot lesions as a consequence mainly of neuropathy and peripheral vascular disease. The prevalence of active foot ulceration varies from approximately 1% in certain European and North American studies to more than 11% in reports from some African countries. Although there have been many developments in recent years which encourage optimism for future improvement in diabetic foot care, there is still much to be done; the recent data from the Netherlands show that with a concerted team approach, it is possible to increase the numbers of foot clinics with the provision of podiatry services by more than 100%. However, many countries still lack proper podiatry and specialist nursing provision and there remains much to be done in the next millennium to improve the lot of the diabetic patient with foot problems.

Efficacy of injected liquid silicone in the diabetic foot to reduce risk factors for ulceration: a randomized double-blind placebo-controlled trial

OBJECTIVE

To investigate the effectiveness of injecting liquid silicone in the diabetic foot to reduce risk factors for ulceration in a randomized double-blind placebo-controlled trial.

RESEARCH DESIGN AND METHODS

A total of 28 diabetic neuropathic patients without peripheral vascular disease were randomized to active treatment with 6 injections of 0.2 ml liquid silicone in the plantar surface of the foot or to treatment with an equal volume of saline (placebo). No significant differences were evident regarding age or neuropathy status between the 2 groups. All injections were under the metatarsal heads at sites of calluses or high pressures. Barefoot plantar pressures (pedobarography) and plantar tissue thickness under the metatarsal heads (Planscan ultrasound device) were measured at baseline and at 3, 6, and 12 months after the first injection. Injection sites were photographed at all stages, and callus formation was scored as a change from baseline. Throughout the study, patients were treated by the same podiatrist for all podiatry treatment.

RESULTS

Patients who received silicone treatment had significantly increased plantar tissue thickness at injection sites compared with the placebo group (1.8 vs. 0.1 mm) (P < 0.0001) and correspondingly significantly decreased plantar pressures (-232 vs. -25 kPa) (P < 0.05) at 3 months, with similar results at 6 and 12 months. A trend was noted toward a reduction of callus formation in the silicone-treated group compared with no change in the placebo group.

CONCLUSIONS

The results confirm the efficacy of plantar silicone injections in reducing recognized risk factors associated with diabetic foot ulceration.

Lack of insulin-like growth factor 1 (IGF1) in the basal keratinocyte layer of diabetic skin and diabetic foot ulcers

Wound healing, including re-epithelialization, is delayed in diabetes. Growth factors influence the healing process and amongst these, insulin-like growth factor (IGF) has been shown to stimulate keratinocyte proliferation in vitro. Monoclonal antibodies to insulin-like growth factors 1 and 2 (IGF1 and IGF2) were used to investigate their distribution in diabetic foot ulcers and surrounding tissues by immunohistochemistry, compared with diabetic and non-diabetic uninjured skin. IGF2 was found throughout the epidermis (stratum granulosum, spinosum, and basale) in all three groups. Staining for IGF2 was intense in both normal and diabetic skin as well as in diabetic foot ulcers, being greatest at the ulcer edge. IGF1, in comparison, was found throughout the epidermis of non-diabetic skin; expression was restricted to the stratum granulosum and spinosum of uninjured diabetic skin and was absent in the basal layer at the ulcer edge. A similar absence of IGF1 in dermal fibroblasts was found in tissue sections from diabetic patients. This lack of expression of IGF1 within the basal layer and fibroblasts may contribute to retarded wound healing in diabetes mellitus.

Low paraoxonase activity in type II diabetes mellitus complicated by retinopathy

Human serum paraoxonase 1 (PON1) is located on high-density lipoprotein and has been implicated in the detoxification of organophosphates, and possibly in the prevention of lipid peroxidation of low-density lipoprotein. PON1 has two genetic polymorphisms, both due to amino acid substitutions: one involving glutamine (Q genotype) and arginine (R genotype) at position 192, and the other involving leucine (L genotype) and methionine (M genotype) at position 55. We investigated the effects of these polymorphisms, and of a polymorphism of the PON2 gene at position 310 (Cys/Ser; C and S genotypes respectively), on serum PON1 activity and concentration, plasma lipids and lipoproteins and glycaemic control in 93 individuals with type II diabetes with no complications and in 101 individuals with type II diabetes with retinopathy. Serum PON1 activity in the group with no complications [median 164.1 nmol.min(-1).ml(-1) (range 8.0-467.8)] was significantly higher than in the group with retinopathy [113.4 nmol. min(-1).ml(-1) (3.0-414.6)] (P<0.001), but the serum PON1 concentration was not different between the groups. The gene frequencies of the PON1-55 and PON1-192 polymorphisms and of the PON2-310 polymorphism were not different between the study populations. The PON1-55 and PON1-192 polymorphisms affected PON1 activity in the way described in a previous study of a control group and subjects with type II diabetes. The PON2-310 polymorphism also significantly affected serum PON1. PON1 activity was significantly higher in individuals with the PON2-310 CC genotype in both groups with type II diabetes, and the PON1 concentration was significantly higher in PON2-310 CC homozygotes with no complications than in the group with retinopathy. Neither the PON1-55 nor the PON1-192 polymorphism was correlated with the serum lipid or lipoprotein concentration in either group. In the group with retinopathy (but not the group with no complications), all three PON polymorphisms were correlated with glycaemic control, which was worse for the PON1-55 genotypes in the order MM>LM>LL (P=0.0032), for the PON1-192 genotypes in the order RR>QR>QQ (P=0.011) and for the PON2-310 genotypes in the order CC>CS>SS (P=0.010). Low serum PON1 activity in retinopathy may be related to an increased tendency for lipid peroxidation. Our findings thus raise the possibility that, in retinopathy, the PON2 gene may influence PON1, and that an inter-relationship between the PON1 and PON2 genes may influence glycaemic control in subjects with type II diabetes complicated by retinopathy.

Clinico-pathological features of postural hypotension in diabetic autonomic neuropathy

We report the clinico-pathological features and management of a 49-year-old male with a 30-year history of Type 1 diabetes mellitus who had nephropathy (proteinuria 1.81 g/24 h, creatinine 136 micromol/l), proliferative retinopathy and severe somatic and autonomic neuropathy. A sural nerve biopsy demonstrated marked myelinated fibre loss with unmyelinated fibre degeneration and regeneration combined with extensive endoneurial microangiopathy. The management of the patient's blood pressure problems (supine hypertension) and symptomatic postural hypotension is discussed.

Specific fiber deficits in sensorimotor diabetic polyneuropathy correspond to cytotoxicity against neuroblastoma cells of sera from patients with diabetes

OBJECTIVE

Neuropathy is the most common complication of diabetes, and toxic serum factors may contribute to its genesis.

RESEARCH DESIGN AND METHODS

We assessed neurotoxicity in the serum of 39 diabetic patients and correlated it with clinical measures of somatic and autonomic nerve fiber damage. Sera were applied to N1E-115 and VSC4.1 neuroblastoma cells in vitro as models of sensory/autonomic (S/A) and motor neurons, respectively. Neurotoxicity was measured as either complete or near-complete cell death (highly toxic), inhibited cell growth (moderately toxic), or normal cell proliferation (nontoxic) compared with pooled human serum controls during culture over 4 days.

RESULTS

There was an inverse correlation between neurotoxicity and vibration perception threshold (P < 0.01). Age (P < 0.02), duration of diabetes (P < 0.02), and HbA1c (P < 0.03) correlated with neurotoxicity, suggesting that glycation may contribute to cytotoxicity in this model. S/A neurotoxicity occurred more frequently in the sera of patients with type 1 (19 of 25) than type 2 (5 of 14) diabetes (P < 0.02). None of the sera from either type 1 or type 2 diabetic patients displayed neurotoxicity on VSC4.1 cells, whereas sera from patients with motor neuropathy were highly toxic.

CONCLUSIONS

These studies indicate that there is a relationship between the specific nerve fiber dysfunction in the patient and the type of neuronal cell killed, not only for diabetic neuropathy but also for known forms of autoimmune neuropathies. Such toxic factors may contribute to diabetic neuropathy by acting in concert with hyperglycemia to damage sensory/autonomic neurons.

Structural abnormalities do not explain the early functional abnormalities in the peripheral nerves of the streptozotocin diabetic rat

The streptozotocin (STZ)-diabetic rat, the most commonly employed model of experimental diabetic neuropathy, is characterised by a reduction in nerve conduction velocity, pain threshold and blood flow. Whether or not structural abnormalities underlie these functional abnormalities is unclear. 10 adult male Sprague-Dawley STZ-diabetic rats (diabetes duration 27 d) and 10 age-matched (23 wk) control animals were studied. Motor nerve conduction velocity (m s(-1)) was significantly reduced in diabetic (41.31 +/- 0.8) compared with control (46.15 +/- 1.5) animals (P < 0.001). The concentration of sciatic nerve glucose (P < 0.001), fructose (P < 0.001) and sorbitol (P < 0.001) was elevated, and myoinositol (P < 0.001) was reduced in diabetic compared with control animals. Detailed morphometric studies demonstrated no significant difference in fascicular area, myelinated fibre density, fibre and axon areas as well as unmyelinated fibre density and diameter. Endoneurial capillary density, basement membrane area and endothelial cell profile number did not differ between diabetic and control animals. However, luminal area (P < 0.03) was increased and endothelial cell area (P < 0.08) was decreased in the diabetic rats. We conclude there is no detectable structural basis for the reduction in nerve conduction velocity, pain threshold or blood flow, observed in the streptozotocin diabetic rat.

Benefits of a multidisciplinary approach in the management of recurrent diabetic foot ulceration in Lithuania: a prospective study

OBJECTIVE

To assess the ability of a multidisciplinary approach to diabetic foot care to reduce the incidence of recurrent ulceration and amputations compared with standard care in a 2-year prospective study.

RESEARCH DESIGN AND METHODS

A total of 145 patients with a past history of neuropathic foot ulcers but no evidence of peripheral vascular disease entered the study. Subjects were screened for their neuropathic and vascular status at baseline, and all received identical foot care education. The intervention group (n = 56) was followed by the multidisciplinary team of physicians, nurses, and podiatrists with regular podiatry and reeducation every 3 months and the provision of specialty footwear as required. The standard treatment group was followed in local clinics on a trimonthly basis and received identical screening and education at baseline.

RESULTS

There were no significant differences at baseline in age (intervention 59.2+/-13.4, standard treatment 58.5+/-11.5 years), duration of diabetes (14.0+/-7.1 vs. 15.6+/-7.8 years), or neuropathic status (vibration perception threshold [VPT]: 31.1+/-12.1 vs. 33.9+/-11.3 V, neuropathy disability score [NDS]: 8.1+/-1.4 vs. 7.9+/-1.7). All patients had an ankle brachial pressure index (ABPI) of >0.9 and at least one palpable foot pulse. Significantly fewer recurrent ulcers were seen in the intervention group than in the standard treatment group during the 2-year period (30.4 vs. 58.4%, P < 0.001).

CONCLUSIONS

This prospective study has demonstrated the effectiveness of a multidisciplinary approach to diabetic foot care together with the provision of specialty footwear in the long-term management of high-risk patients with a history of neuropathic foot ulcers.

Methicillin-resistant Staphylococcus aureus: an increasing problem in a diabetic foot clinic

AIM

To study the prevalence of pathogenic organisms and the prevalence and outcome of methicillin-resistant Staphylococcus aureus (MRSA) infection in foot ulcers in diabetic patients.

METHODS

A retrospective analysis of wound swabs taken from infected foot ulcers in diabetic patients, selected from an outpatient diabetic foot clinic. Seventy-five patients (79 ulcers) with positive wound swabs were included. Size of ulcer and time to healing, in particular for MRSA-infected ulcers, were measured in all patients.

RESULTS

Gram-positive aerobic bacteria were the commonest micro-organism isolated (56.7%) followed by gram-negative aerobic bacteria and anaerobes (29.8% and 13.5%, respectively). Of the gram-positive aerobes, S. aureus was found most frequently and 40% were MRSA. MRSA was isolated more commonly in patients treated with antibiotics prior to the swab compared to those who had not received antibiotics (P = 0.01). Patients whose foot ulcers were infected by MRSA had longer healing time than patients whose ulcers were infected by methicillin-sensitive S. aureus (mean (range) 35.4 (19-64) and 17.8 (8-24) weeks, respectively, P = 0.03).

CONCLUSION

MRSA infection is common in diabetic foot ulcers and is associated with previous antibiotic treatment and prolonged time to healing. Further studies are required to assess the need for antibiotics in treating foot ulcers in diabetes and to assess the optimum therapeutic approach to this problem.

The role of nitric oxide synthase isoforms and arginase in the pathogenesis of diabetic foot ulcers: possible modulatory effects by transforming growth factor beta 1

AIMS/HYPOTHESIS

L-arginine, an amino acid involved in wound healing, is metabolised by one of two pathways; nitric oxide synthase and arginase. If metabolised by nitric oxide synthase, this can result in tissue destruction, or matrix deposition if metabolised by arginase. The aim therefore was to investigate the role of these enzymes in the pathogenesis of diabetic foot ulcers.

METHODS

The activity, proteins by Western blot analysis and cellular distribution (using immunocytochemistry) of these enzymes were measured in diabetic foot ulcers, diabetic skin and normal skin.

RESULTS

Total and inducible nitric oxide synthase (p < 0.001) and endothelial nitric oxide synthase were increased in diabetic ulcers compared with diabetic and normal skin and were associated with increased plasma nitrite concentrations in diabetic ulcers (p < 0.05). Inducible nitric oxide synthase was the major isoform, with the macrophage being the predominant cellular source. Similarly arginase activity was increased (p < 0.01) in diabetic ulcers. The protein levels corroborated with the activity data, with the fibroblast being the major cellular source. The spatial and cellular distribution of the two enzyme systems was distinct. Transforming growth factor-beta1 was decreased in diabetic ulcers in comparison with diabetic skin and normal skin.

CONCLUSION/INTERPRETATION

Increased nitric oxide synthase activity in diabetic foot ulcers may be responsible for the impaired healing in this disease. Furthermore, the increased activity of arginase could account for the characteristic callus formation around these ulcers. In addition, the lower concentrations of transforming growth factor-betal in diabetic ulcers may explain the raised concentrations of nitric oxide in this condition.

A comparative study of the Podotrack, a simple semiquantitative plantar pressure measuring device, and the optical pedobarograph in the assessment of pressures under the diabetic foot

AIMS

To test the Podotrack, a simple inexpensive semiquantitative footprint mat, for potential use as a screening tool for high plantar pressures, against the optical pedobarograph (a computerized device).

METHODS

The Podotrack was superimposed on the pedobarograph for simultaneous measurement of pressures from both systems. Three independent observers quantified the pressures of Podotrack footprints from healthy controls and diabetic patients, both before (n=164) and after (n=183) training. The sensitivity of the Podotrack to identify high pressure areas measured by the pedobarograph (> 12.3 kg/cm2) was 78.7%, 45.8% and 44.3% (observer A, B and C) before training, but improved to 96.2%, 92.4% and 91.1% after training (P<0.01). Specificity for all three observers was more than 90% before and after training. Inter-observer agreement improved significantly after training (P<0.001).

CONCLUSION

After a simple training of the observers, the Podotrack identified approximately all high pressure areas, suggesting that the Podotrack could be a useful screening tool to identify areas at risk of ulceration in diabetic patients. We recommend a standard training package for new Podotrack users, to optimize identification of diabetic patients at risk of foot ulceration.

Perineurial abnormalities in the spontaneously diabetic dog

Structural abnormalities of the perineurium from six spontaneously diabetic dogs (diabetes duration 4-8 years and six control animals were quantified using detailed electron microscopic morphometric methods on superficial peroneal nerve biopsy specimens. Total perineurial sheath thickness (microm) was significantly increased in diabetic (8.8+/-0.6) compared to control animals (6.2+/-0.3) (P < 0.02). This was attributed to a significant increase in the mean perineurial lamellar width in diabetic (0.49+/-0.03) compared to control (0.40+/-0.01) (P < 0.04) animals. The number of lamellae also showed a non-significant increase in diabetic animals (7.8+/-0.4) compared to controls (6.9+/-0.13) (P < 0.06). There was no change in the mean interlamellar space in diabetic (0.7+/-0.05) compared to control (0.6+/-0.06) (P = 0.15) animals. The total interlamellar space was increased in diabetic (5.7+/-0.5) compared to control (4.1+/-0.36) (P < 0.04) animals. The perineurial cell basement membrane thickness (nm) was significantly increased in diabetic (126.9+/-9.8) compared to control (62.8+/-6.1) (P < 0.005) animals. The current study has demonstrated significant abnormalities of the perineurium in the spontaneously diabetic dog, which may have relevance to the pathogenesis of diabetic neuropathy.

Diabetic foot ulcers: A framework for prevention and care

Complications secondary to diabetes, such as diabetic foot ulcers, continue to be a major worldwide health problem. At the same time, health care systems are changing rapidly, causing concern about the quality of patient care. While the ultimate effect of current changes on health care professionals and patient outcomes remain uncertain, measures commonly used to reduce costs, e.g., disease and multi- disciplinary management strategies, have been shown to help prevent the occurrence of diabetic ulcers. In addition, utilizing a multi- disciplinary approach, the principles of off-loading and optimal wound care, the vast majority of diabetic foot ulcers can be expected to heal within 12 weeks of treatment. Education of primary care providers and patients is paramount.

Causal pathways for incident lower-extremity ulcers in patients with diabetes from two settings

OBJECTIVE

To determine the frequency and constellations of anatomic, pathophysiologic, and environmental factors involved in the development of incident diabetic foot ulcers in patients with diabetes and no history of foot ulcers from Manchester, U.K., and Seattle, Washington, research settings.

RESEARCH DESIGN AND METHODS

The Rothman model of causation was applied to the diabetic foot ulcer condition. The presence of structural deformities, peripheral neuropathy, ischemia, infection, edema, and callus formation was determined for diabetic individuals with incident foot ulcers in Manchester and Seattle. Demographic, health, diabetes, and ulcer data were ascertained for each patient. A multidisciplinary group of foot specialists blinded to patient identity independently reviewed detailed abstracts to determine component and sufficient causes present and contributing to the development of each patient's foot ulcer. A modified Delphi process assisted the group in reaching consensus on component causes for each patient. Estimates of the proportion of ulcers that could be ascribed to each component cause were computed.

RESULTS

From among 92 study patients from Manchester and 56 from Seattle, 32 unique causal pathways were identified. A critical triad (neuropathy, minor foot trauma, foot deformity) was present in > 63% of patient's causal pathways to foot ulcers. The components edema and ischemia contributed to the development of 37 and 35% of foot ulcers, respectively. Callus formation was associated with ulcer development in 30% of the pathways. Two unitary causes of ulcer were identified, with trauma and edema accounting for 6 and < 1% of ulcers, respectively. The majority of the lesions were on the plantar toes, forefoot, and midfoot.

CONCLUSIONS

The most frequent component causes for lower-extremity ulcers were trauma, neuropathy, and deformity, which were present in a majority of patients. Clinicians are encouraged to use proven strategies to prevent and decrease the impact of modifiable conditions leading to foot ulcers in patients with diabetes.

Peripheral neuropathy

Diabetes mellitus is the most common cause of peripheral neuropathy in the western world. There are many other causes of peripheral neuropathy, and a systematic approach (i.e., clinical, electrophysiologic, biochemical, and histologic) may be necessary to ascertain the underlying cause. Of paramount importance, irrespective of the cause, is the prevention of insensitive foot ulceration and foot deformity.

Effect of angiotensin-converting-enzyme (ACE) inhibitor trandolapril on human diabetic neuropathy: randomised double-blind controlled trial

BACKGROUND

Diabetes is a common cause of polyneuropathy. The development and progression of nephropathy, retinopathy, and neuropathy are closely related. Angiotensin-converting enzyme (ACE) inhibitors delay progression of both nephropathy and retinopathy. We investigated the effect of ACE inhibition on diabetic neuropathy.

METHODS

We recruited 41 normotensive patients with type I or type II diabetes and mild neuropathy into a randomised double-blind placebo-controlled trial. Changes in the neuropathy symptom and deficit scores, vibration-perception threshold, peripheral-nerve electrophysiology, and cardiovascular autonomic function, were assessed at 6 and 12 months. The primary endpoint was the change in peroneal nerve motor conduction velocity.

FINDINGS

We found no significant difference at baseline for age, HbA1c, blood pressure, or severity of neuropathy between two groups. There was no change in HbA1c over the treatment period. Peroneal motor nerve conduction velocity (p=0.03) and M-wave amplitude (p=0.03) increased, and the F-wave latency (p=0.03) decreased and sural nerve action potential amplitude increased (p=0.04) significantly after 12 months of treatment with trandolapril compared with placebo. Vibration-perception threshold, autonomic function, and the neuropathy symptom and deficit score showed no improvement in either group.

INTERPRETATION

The ACE inhibitor trandolapril may improve peripheral neuropathy in normotensive patients with diabetes. Larger clinical trials are needed to confirm these data before changes to clinical practice can be advocated.