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Biomedical subjects

David G Armstrong

Publications and source records attributed to David G Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed2003

Diabetic foot syndrome: evaluating the prevalence and incidence of foot pathology in Mexican Americans and non-Hispanic whites from a diabetes disease management cohort.

OBJECTIVE: To report the incidence of diabetes-related lower-extremity complications in a cohort of patients enrolled in a diabetes disease management program. RESEARCH DESIGN AND METHODS: We evaluated screening results and clinical outcomes for the first 1,666 patients enrolled in a disease management program for a period of 24 months (50.3% men, aged 69.1 +/- 11.1 years). RESULTS: The incidence of ulceration, infection, amputation, and lower-extremity bypass was 68.4, 36.5, 5.9, and 7.7 per 1,000 persons with diabetes per year. Amputation incidence was higher in Mexican Americans than in non-Hispanic whites (7.4/1,000 vs. 4.1/1,000; P = 0.003, odds ratio [OR] 1.8, 95% CI 1.2-2.7). The amputation-to-ulcer ratio was 8.7%. The incidence of Charcot arthropathy was 8.5/1,000 per year. Charcot was more common in non-Hispanic whites than in Mexican Americans (11.7/1,000 vs. 6.4/1,000; P = 0.0001, 1.8, 1.3-2.5). The prevalence of peripheral vascular disease was 13.5%, with no significant difference based on ethnicity (P = 0.3). There was not a significant difference in incidence of foot infection (P = 0.9), lower-extremity bypass (P = 0.3), or ulceration (P = 0.1) based on ethnicity. However, there were more failed bypasses in Mexican Americans (33%) than in non-Hispanic whites (7.1%). Mexican Americans were 3.8 times more likely to have a failed bypass (leading to an amputation) or be diagnosed as "nonbypassable" than non-Hispanic whites (75.0 vs. 44.0%; P = 0.01, 3.8, 1.2-11.8). CONCLUSIONS: The incidence of amputation is higher in Mexican Americans, despite rates of ulceration, infection, vascular disease, and lower-extremity bypass similar to those of non-Hispanic whites. There may be factors associated with failed or failure to bypass that mandate further investigation.

Age of Onset↗
PubMed2003

Activity patterns of patients with diabetic foot ulceration: patients with active ulceration may not adhere to a standard pressure off-loading regimen.

OBJECTIVE: To evaluate the activity of patients with diabetic foot ulcerations and their adherence to their pressure off-loading device. RESEARCH DESIGN AND METHODS: We enrolled 20 subjects treated for neuropathic diabetic foot wounds corresponding to University of Texas grade 1 stage A. All were off-loaded using a removable cast walker (RCW). We recorded the total activity (measured in activity steps per day) taken on a waist-worn computerized accelerometer. We subsequently correlated this to activity recorded on an RCW-mounted accelerometer, which was not readily accessible to the patient. RESULTS: There were a mean 1219.1 +/- 821.2 activity units (steps) taken per patient per day. Patients logged significantly more daily activity units with the protective RCW off than with it on (873.7 +/- 828.0 vs. 345.3 +/- 219.1, P = 0.01). This amounts to only 28% of total daily activity recorded while patients were wearing their RCW. Although a total of 30% of the patients in the study recorded more daily activity units while wearing the device, this subset most adherent to their off-loading regimen still only wore the device for a total of 60% of their total daily activity. CONCLUSIONS: Subjects with diabetic foot ulcerations appear to wear their off-loading devices for only a minority of steps taken each day. This may partially explain the poor results reported from many trials of agents designed to help speed the healing of these wounds. Control of this important aspect of care with less easily removable devices may increase the prevalence of healing.

Age of Onset↗
PubMed2003

Pain in diabetic foot ulcers.

People with diabetes who have foot ulcers require adequate vasculature, infection control, and pressure offloading to heal. Pain is uncommon in diabetic foot disorders, but it may herald the onset of limb-threatening complications such as deep infection, Charcot change, or critical ischemia. Although neuropathy is most commonly painless, a minority of patients experience disturbing burning, stinging, stabbing, or shooting sensations. Using the "preparing the wound bed" model, the cause of pain in the person with diabetic foot problems can be diagnosed systematically and important therapeutic measures can be instituted in an attempt to prevent potential complications, including amputation.

Diabetic Foot↗
PubMed2002

Healing the diabetic wound and keeping it healed: modalities for the early 21st century.

The incidence of lower extremity wounds, infections, and amputations continues to increase worldwide. Fortunately, the past decade has seen a surge of activity in research into new modalities in wound healing and, even more recently, prevention. This article discusses the basic physiology of wound healing, with particular attention being paid to current and potential wound healing modalities. These include, among other modalities, discussions of bioengineered skin, hyaluronic acid, subatmospheric pressure therapy, growth factors, and endogenous cytokine stimulation. Emerging concepts targeting prevention through novel methods of patient empowerment, dermal thermometry, and computerized activity monitoring are also discussed.

Diabetes Complications↗
PubMed2002

The effect of silicone injections in the diabetic foot on peak plantar pressure and plantar tissue thickness: a 2-year follow-up.

OBJECTIVE: To report the efficacy of injected liquid silicone (ILS) in the foot at 2 years after administration. DESIGN: Randomized controlled trial. SETTING: Diabetic foot clinic in the United Kingdom. PARTICIPANTS: Twenty-eight diabetic neuropathic patients, randomized into an active treatment group (n=14) and a placebo group (n=14). INTERVENTION: Participants were given either 6 injections of 0.2mL of liquid silicone (silicone group) or equal volumes of saline (placebo group) under metatarsal head sites with callus. MAIN OUTCOME MEASURES: Plantar tissue thickness and plantar pressures were measured at 3, 6, 12, and 24 months postinjection. RESULTS: At 12 months, the plantar tissue thickness in the silicone group had increased by a mean 1.6+/-0.9mm (P=.001), and remained increased at 24 months (1.1+/-0.7mm, P=.003). Peak plantar pressure in the silicone group was reduced at 12 months (-165.0+/-253.5kPa, P=.03), but not at 24 months. There was no change in tissue thickness or peak plantar pressure in the placebo group at 12 and 24 months. The reduction in the pressure time integral (PTI) in the silicone group did not reach significance at 12 months (-.71+/-1.17kPa/s, P=.055). Although PTI returned to baseline at 24 months for the silicone group, it was significantly increased in the placebo group (.64+/-.37kPa/s, P=.043), suggesting that silicone may still exhibit some pressure-reducing properties after 24 months. CONCLUSIONS: The results indicate that at 24 months postinjection the cushioning properties of ILS have reduced, suggesting that booster injections may be required in certain patients.

Diabetic Foot↗
PubMed2002

The forefoot-to-rearfoot plantar pressure ratio is increased in severe diabetic neuropathy and can predict foot ulceration.

OBJECTIVE: We have previously demonstrated that high plantar pressures can predict foot ulceration in diabetic patients. The aim of the present study was to evaluate both the relationship between forefoot and rearfoot plantar pressure in diabetic patients with different degrees of peripheral neuropathy and their role in ulcer development. RESEARCH DESIGN AND METHODS: Diabetic patients of a 30-month prospective study were classified according to the neuropathy disability score: scores of 0, 1-5, 6-16, and 17-28 are defined as absent (n = 20), mild (n = 66), moderate (n = 95), and severe (n = 57) neuropathy, respectively. The F-Scan mat system was used to measure dynamic plantar pressures. The peak pressures under the forefoot and the rearfoot were selectively measured for each foot, and the forefoot-to-rearfoot ratio (F/R ratio) was calculated. RESULTS: Foot ulcers developed in 73 (19%) feet. The peak pressures were increased in the forefoot of the severe and moderate neuropathic groups compared with the mild neuropathic and non-neuropathic groups (6.2 +/- 4.5 and 3.8 +/- 2.7 vs. 3.0 +/- 2.1 and 3.3 +/- 2.1 kg/cm(2) [mean +/- SD], respectively; P < 0.0001). The rearfoot pressures were also higher in the severe and moderate neuropathic groups compared with the mild neuropathic and non-neuropathic groups (3.2 +/- 2.0 and 3.2 +/- 1.9 vs. 2.5 +/- 1.3 and 2.3 +/- 1.0, respectively; P < 0.0001). The F/R ratio was increased only in the severe group compared with the moderate and mild neuropathic and non-neuropathic groups (2.3 +/- 2.4 vs. 1.5 +/- 1.2, 1.3 +/- 0.9, and 1.6 +/- 1.0, respectively; P < 0.0001). In a logistic regression analysis, both forefoot pressure (odds ratio 1.19 [95% CI 1.11-1.28], P < 0.0001) and the F/R ratio (1.37 [1.16-1.61], P < 0.0001) were related to risk of foot ulceration, whereas rearfoot pressure was not. CONCLUSIONS: Both the rearfoot and forefoot pressures are increased in the diabetic neuropathic foot, whereas the F/R ratio is increased only in severe diabetic neuropathy, indicating an imbalance in pressure distribution with increasing degrees of neuropathy. This may lend further evidence toward the concept that equinus develops in the latest stages of peripheral neuropathy and may play an important role in the etiology of diabetic foot ulceration.

Adult↗
PubMed2002

The role of matrix metalloproteinases in wound healing.

The structure, classification, function, and regulation of matrix metalloproteinases in normal and abnormal wound healing is discussed. Results from key studies suggest that neutrophil-derived matrix metalloproteinase 8 (MMP-8) is the predominant collagenase present in normal healing wounds, and that overexpression and activation of this collagenase may be involved in the pathogenesis of nonhealing chronic leg ulcers. Excessive collagenolytic activity in these chronic wounds is possible because of the reduced levels of tissue inhibitor metalloproteinase 1 (TIMP-1). However, until recently, there have been no studies evaluating levels of matrix metalloproteinase or tissue inhibitors of metalloproteinase activity in chronic diabetic foot wounds. Improving basic knowledge and pharmaceutical intervention in this area ultimately may help clinicians identify and proactively intervene in an effort to prevent normal wounds from becoming chronic. This may prevent the high prevalence of morbidity associated with this significant health problem.

Humans↗
PubMed2002

The Diabetic Foot 2001. A summary of the proceedings of the American Diabetes Association's 61st Scientific Symposium.

This review discusses some of the significant studies and events from the 61st American Diabetes Association's Scientific Symposium. Many of the issues raised at the meeting will form building blocks for future research into offloading, footwear, wound classification, wound healing, tissue engineering, and psychological aspects of therapy and prevention.

Amputation, Surgical↗
PubMed2002

Use of clinical laboratory parameters to evaluate wound healing potential in diabetes mellitus.

Clinicians caring for chronic wounds can easily overlook nutritional status. Patients with diabetes are at high risk for primary and secondary malnutrition. Although profiles exist defining the extent of the deficiency, the process of wound healing and the interactions of the macronutrients and micronutrients necessary to accomplish it must first be understood. In elderly patients with diabetes, additional factors such as liver and renal function, the interdependence of the immune system, and protein synthesis, also must be considered. This article provides a practical format to assist clinicians in better evaluating this often difficult-to-assess area of care.

Clinical Laboratory Techniques↗
PubMed2002

Chemical matrixectomy for ingrown toenails: Is there an evidence basis to guide therapy?

Chemical matrixectomy for ingrown toenails is one of the most common surgical procedures performed on the foot. The procedure was first described in 1945 by Otto Boll, who discussed the use of phenol to correct ingrown toenails. In the years that followed, many variations of technique and method have been described. This article reviews the pertinent literature detailing chemical matrixectomies and advocates the use of an evidence basis for care.

Diabetic Foot↗
PubMed2002

Ankle equinus deformity and its relationship to high plantar pressure in a large population with diabetes mellitus.

The authors undertook a study to evaluate the prevalence of ankle equinus and its potential relationship to high plantar pressure in a large, urban population with diabetes mellitus. The first 1,666 consecutive people with diabetes (50.3% male; mean [+/-SD] age, 69.1 +/- 11.1 years) presenting to a large, urban, managed-care outpatient clinic were enrolled in this longitudinal, 2-year outcomes study. Patients received a standardized medical and musculoskeletal assessment at the time of enrollment, including evaluation at an onsite gait laboratory. Equinus was defined as less than 0 degrees of dorsiflexion at the ankle. The overall prevalence of equinus in this population was 10.3%. Patients with equinus had significantly higher peak plantar pressures than those without the deformity and were at nearly three times greater risk for presenting with elevated plantar pressures. There were no significant differences in age, weight, or sex between the two groups. However, patients with equinus had a significantly longer duration of diabetes than those without equinus. Having a high index of suspicion for this deformity and subsequently addressing it through conservative or surgical means may help to reduce the risk of foot ulceration and amputation.

Aged↗
PubMed2002

Outcomes of subatmospheric pressure dressing therapy on wounds of the diabetic foot.

The purpose of this retrospective study was to evaluate outcomes of people with large diabetic foot wounds treated with subatmospheric pressure dressing therapy immediately following surgical wound debridement. Data were abstracted from the medical records of 31 consecutive patients with diabetes, 77.4% male (n = 24), aged 56.1 +/- 11.7 years, presenting for care at two large multidisciplinary wound care centers. All patients received surgical debridement for indolent diabetic foot wounds and were subsequently started on a regimen of subatmospheric pressure dressing therapy delivered using a vacuum-assisted closure device for a mean of 4.7 +/- 4.2 weeks (mode = 2 weeks) using a protocol that called for cessation of therapy when the wound bed approached 100% coverage with granulation tissue with no exposed tendon, joint capsule, or bone. Outcomes evaluated included time to complete wound closure, proportion of patients achieving wound healing at the level of initial debridement, and complications associated with use of the device. The mean duration of wounds before therapy was 25.4 +/- 23.8 weeks. In patients treated with subatmospheric pressure dressing therapy, 90.3% (n = 28) of wounds healed at the level of debridement without the need for further bony resection in a mean 8.1 +/- 5.5 weeks. The remaining 9.7% (n = 3) went on to higher level amputation (below knee amputation = 3.2%, [n = 1] and transmetatarsal amputation = 6.5% [n = 2]). Complications included periwound maceration (19.4% [n = 6]), periwound cellulitis (3.2% [n = 1]), and deep space infection (3.2% [n = 1]). The authors concluded that appropriate use of subatmospheric pressure dressing therapy to achieve a rapid granular bed in diabetic foot wounds may have promise in treatment of this population at high risk for amputation and that a large, randomized trial is now indicated.

Atmospheric Pressure↗
PubMed2002

Offloading diabetic foot wounds using the scotchcast boot: a retrospective study.

A retrospective study was conducted to evaluate treatment outcomes associated with the treatment of diabetic foot ulcers using the Scotchcast boot. Data were extracted from the records of 180 patients with diabetes, 150 (83.3%) male, with a mean age of 55.3 +/- 10.9 years undergoing treatment for noninfected, non-ischemic neuropathic diabetic foot wounds at a university teaching hospital's tertiary care outpatient clinic. All patients who met the criteria were treated with the Scotchcast boot as the sole form of pressure relief. The average follow-up for each patient was 85.9 +/- 30.6 months (range 34.2 to 147.7 months). The mean time to healing for all patients was 130.5 +/- 106.7 days. Superficial (Grade 1) wounds healed significantly faster than deep (Grade 3) wounds (111.5 +/- 98.2 versus 180.8 +/- 138.8 days, P = 0.01) and 144 (80%) wounds healed during the follow-up period. Of the 36 (20%) that did not heal with Scotchcast boot therapy, 10 went on to more proximal amputation (5.6% of total population), two required surgical intervention to heal their wounds (0.6% of total population), one patient died with an unhealed wound (0.6% of total population), 23 patients (12.8% of total population) were lost to follow-up, and 47 (26%) died. Experience and the results of this and other studies suggest that this removable modality may be useful in outpatient care of deeper or complex wounds that require frequent inspection, but a device that ensures compliance may be the preferred treatment of superficial wounds.

Analysis of Variance↗
PubMedDate not supplied

Diabetic lower extremity infection: influence of physical, psychological, and social factors.

AIMS: Although literature is scarce, it is a common belief that patients with lower social background are more prone to diabetic complications. The purpose of this study was to identify local, systemic, and psychosocial risk factors that can lead to severe foot infections and subsequent amputations. METHODS: This study was set up as a case-control study. We enrolled 112 persons with diabetes, in an approximately 1:1 case to control ratio. Cases were defined as patients admitted to the hospital with a severe foot infection, possibly necessitating a lower extremity amputation; controls were patients admitted for nonemergent medical or surgical cause. Study participants received a physical examination and interview to evaluate exposure variables, including demographic data, general medical, surgical, diabetes, and diabetes-related complication history. Socioeconomic status was quantified with the Duncan socioeconomic impact and Siegel prestige score. The patient's knowledge of foot care was evaluated as well. The risks for severe foot infection of social, economical, and physical risk factors were compared in a stepwise logistic regression analysis. RESULTS: The following variables were significant factors for severe foot infection: history of previous amputation [odds ratio (OR)=19.9, P=.01], peripheral vascular disease (OR=5.5, P=.007), and peripheral neuropathy, as measured with vibratory perception threshold (OR 3.4, P=.044). Social and economic factors were not significant in this model. CONCLUSIONS: These data suggest that physical risk factors are important in foot infection and that the additional risk of socioeconomic status or knowledge of foot care is limited in this population.

Amputation, Surgical↗
PubMedDate not supplied

What is the shelf life of physician-mixed antibiotic-impregnated calcium sulfate pellets?

This pilot study was undertaken to evaluate the short-term in vitro antimicrobial stability of both vancomycin- and tobramycin-impregnated calcium sulfate pellets mixed and stored in a clinical setting. Powdered tobramycin sulfate (500 mg) and vancomycin hydrochloride (500 mg) were blended into separate basins containing 25 g of surgical-grade calcium sulfate powder, then mixed with 8 mL of sterile saline. From this admixture, 6.0-mm pellets were produced. These were removed from the sterile container (stored at room temperature) at 1, 7, 30, 60, 90, and 120 days and tested against a variety of pathogenic bacterial isolates by using a modification of the standardized Kirby-Bauer test. Control pellets containing no antibiotic were also evaluated. There was no inhibition of bacterial growth by the non-antibiotic-impregnated (control) pellets. There was no appreciable difference in the zones of inhibition for any of the organisms with pellets stored for 1, 7, 30, 60, 90, or 120 days. Zones of inhibition for the various antibiotics to the strain of organism tested ranged from 17 mm to 30 mm, depending on the pathogenic isolate and the antibiotic evaluated. The zones of inhibition observed were similar to those designating antibiotic susceptibility in the Kirby-Bauer test. The results of this preliminary study suggest that clinician-mixed calcium sulfate pellets containing either vancomycin or tobramycin, when stored under normal room temperature and ambient humidity, appear to maintain their antimicrobial characteristics for at least 120 days.

Anti-Bacterial Agents↗