Rodney M. Stuck

Lower-Extremity Amputation Risk After Charcot Arthropathy and Diabetic Foot Ulcer

OBJECTIVE To compare risks of lower-extremity amputation between patients with Charcot arthropathy and those with diabetic foot ulcers. RESEARCH DESIGN AND METHODS A retrospective cohort of patients with incident Charcot arthropathy or diabetic foot ulcers in 2003 was followed for 5 years for any major and minor amputations in the lower extremities. RESULTS After a mean follow-up of 37 ± 20 and 43 ± 18 months, the Charcot and ulcer groups had 4.1 and 4.7 amputations per 100 person-years, respectively. Among patients <65 years old at the end of follow-up, amputation risk relative to patients with Charcot alone was 7 times higher for patients with ulcer alone and 12 times higher for patients with Charcot and ulcer. CONCLUSIONS Charcot arthropathy by itself does not pose a serious amputation risk, but ulcer complication multiplicatively increases the risk. Early surgical intervention for Charcot patients in the absence of deformity or ulceration may not be advisable.

Mortality Risk of Charcot Arthropathy Compared With That of Diabetic Foot Ulcer and Diabetes Alone

OBJECTIVE The purpose of this study was to compare mortality risks of patients with Charcot arthropathy with those of patients with diabetic foot ulcer and those of patients with diabetes alone (no ulcer or Charcot arthropathy). RESEARCH DESIGN AND METHODS A retrospective cohort of 1,050 patients with incident Charcot arthropathy in 2003 in a large health care system was compared with patients with foot ulcer and those with diabetes alone. Mortality was determined during a 5-year follow-up period. Patients with Charcot arthropathy were matched to individuals in the other two groups using propensity score matching based on patient age, sex, race, marital status, diabetes duration, and diabetes control. RESULTS During follow-up, 28.0% of the sample died; 18.8% with diabetes alone and 37.0% with foot ulcer died compared with 28.3% with Charcot arthropathy. Multivariable Cox regression shows that, compared with Charcot arthropathy, foot ulcer was associated with 35% higher mortality risk (hazard ratio 1.35 [95% CI 1.18–1.54]) and diabetes alone with 23% lower risk (0.77 [0.66–0.90]). Of the patients with Charcot arthropathy, 63% experienced foot ulceration before or after the onset of the Charcot arthropathy. Stratified analyses suggest that Charcot arthropathy is associated with a significantly increased mortality risk independent of foot ulcer and other comorbidities. CONCLUSIONS Charcot arthropathy was significantly associated with higher mortality risk than diabetes alone and with lower risk than foot ulcer. Patients with foot ulcers tended to have a higher prevalence of peripheral vascular disease and macrovascular diseases than patients with Charcot arthropathy. This finding may explain the difference in mortality risks between the two groups.

Theoretical model and Rasch analysis to develop a revised Foot Function Index.

Background: The Foot Function Index (FFI) is a widely used self-reported measure of health-related foot function. Several areas have been identified for potential improvement, and this study responds to such criticisms. The objectives of this study were to: (1) develop a theoretical model of foot functioning, (2) develop a revised FFI (FFI-R), and (3) field-test the FFI-R. Methods: A literature review was conducted to develop the theoretical model. The FFI-R items were developed from the original 23 FFI items, and more items were added as a result of the literature review. A focus group discussion with clinicians and pilot interviews with patients resulted in a final draft of the FFI-R. This draft consisted of four subscales and comprised 68 items with a six-point response scale. The FFI-R was field tested on 92 patients in the podiatry clinic of a Veterans Administration Hospital in the Midwest. Psychometric analyses were conducted with modern item response theory (IRT) methods. Results: A theoretical model of foot functioning was developed. The FFI-R response scale was revised from six to five categories since confusion was found between categories 4 and 5. Rasch analyses indicated a person reliability of 0.96 and item reliability of 0.93. The subscale reliability of pain and stiffness, psychosocial, and disability were all >0.80; the exception was assistive devices (>0.50). Construct validity of FFI-R was supported based on the correlation of 50-ft walk time with an FFI-R total of 0.306, p = 0.018, N = 59. Rasch analyses indicated several items with poor fit statistics and a short form with 34 items was developed. Conclusion: The FFI was revised, and new items were added to compose the FFI-R. The chief theoretical change was adding a psychosocial scale. Both long and short forms had very good psychometric properties.

Syme ankle disarticulation in patients with diabetes

BACKGROUND Syme ankle disarticulation is an amputation level that minimizes disability and preserves function, but it has been used sparingly in patients with diabetes mellitus. Surgeons have avoided this level because of the perceived high risk for wound failure, wound infection, or migration of the heel pad, which makes prosthesis use difficult. METHODS Ninety-seven adult patients with diabetes mellitus who underwent Syme ankle disarticulation because of a neuropathic foot with an infection or gangrene, or both, during an eleven-year period were studied retrospectively. Selection of the amputation level was made on the basis of clinical examination and an assessment of the wound-healing parameters, i.e., vascular inflow, tissue nutrition, and immunocompetence. The average age of the patients was 53.2 +/- 17.5 years. RESULTS Eighty-two patients (84.5%) ultimately achieved wound-healing. When threshold levels for vascular inflow (ultrasound Doppler ischemic index of 0.5 or transcutaneous partial pressure of oxygen between 20 and 30 mm Hg) and tissue nutrition (serum albumin of 2.5 g/dL) were met, an overall success rate of 88% was achieved. Total lymphocyte count (an absolute lymphocyte count of 1500) and the smoking of cigarettes during the study period did not appear to impact wound-healing rates. The overall infection rate was 23%, and it was three times greater in smokers. Most infections were managed with local wound care and antibiotic therapy. At a minimum follow-up of two years, all but two patients were able to walk with a prosthesis. Thirty of the ninety-seven patients died at an average of 57.1 months following surgery. CONCLUSIONS The results of this retrospective review support the value of Syme ankle disarticulation in diabetic patients with infection or gangrene. This function-sparing amputation can be successfully performed with a reasonable risk. Patients managed with a Syme ankle disarticulation appeared to remain able to walk better and to survive longer than similar patients who had a transtibial amputation and served as historical controls. In diabetic patients with dysvascular disease who have adequate vascular inflow to support wound-healing (an ultrasound Doppler ischemic index of 0.5 or a transcutaneous partial pressure of oxygen between 20 and 30 mm Hg), the threshold for the wound-healing parameter of serum albumin appears to be as low as 2.5 g/dL.

Charcot Arthropathy Risk Elevation in the Obese Diabetic Population

PURPOSE To examine the association of obesity, peripheral neuropathy, and other risk factors with the Charcot arthropathy incidence rate in a large diabetic population. METHODS The Department of Veterans Affairs inpatient and outpatient administrative datasets were used to identify persons with diabetes in 2003. Logistic regressions were used to model the likelihood of a person developing Charcot arthropathy as a function of individual characteristics, obesity, peripheral neuropathy, diabetic control, and comorbidities. RESULTS Of Veterans Affairs users with diabetes, 652 (0.12%) were newly diagnosed with Charcot arthropathy in 2003. Compared with persons without obesity or peripheral neuropathy, those with obesity alone were approximately 59% more likely, those with neuropathy alone were 14 times more likely, and those with both obesity and neuropathy were 21 times more likely to develop Charcot arthropathy. Ages 55 to 64 years, diabetes duration 6 years or more, hemoglobin-A1c 7% or more, renal failure, arthritis, and deficiency anemia also were associated with an increased incidence of Charcot arthropathy. CONCLUSION Obesity is significantly associated with an increased incidence of Charcot arthropathy independently of other risk factors. When obesity is combined with neuropathy, the Charcot arthropathy incidence rate increases multiplicatively. Prevention and detection of Charcot arthropathy should take the interaction between obesity and neuropathy into consideration.

Intraosseous lipoma of the calcaneus: A clinicopathologic study of three cases

Intraosseous lipoma is a neoplasm which has classically been regarded in the literature as a rare bone tumor. The tumor has several distinguishing characteristics on plain film radiograph, magnetic resonance imaging, and computerized tomography scan. Due to appearances that are similar to simple bone cysts, infarctions, and other lesions, intraosseous lipomas are often misdiagnosed, possibly accounting for their purported rarity. Diagnosis based on plain film radiographs, magnetic resonance imaging, and computerized tomography scans, and appropriate treatments are discussed. Three case studies of calcaneal intraosseous lipomas are followed through the treatment course from initial presentation to postoperative follow-up. Radiographic studies and surgical procedures are discussed, as well as surgical pathology results that demonstrate the potential misdiagnosis of this tumor.

Significant J-shaped association between body mass index (BMI) and diabetic foot ulcers.

Disagreement exists regarding the relationship between body weight and foot ulceration risk among diabetic persons.

Obesity Paradox in Amputation Risk Among Nonelderly Diabetic Men

The association between BMI and amputation risk is not currently well known. We used data for a cohort of diabetic patients treated in the US Department of Veterans Affairs Healthcare System in 2003. Men aged <65 years at the end of follow‐up were examined for their amputation risk and amputation‐free survival during the next 5 years (2004–2008). Compared to overweight individuals (BMI 25–29.9 kg/m2), the risks of amputation and treatment failure (amputation or death) were higher for patients with BMI <25 kg/m2 and were lower for those with BMI ≥30 kg/m2. Individuals with BMI ≥40 kg/m2 were only half as likely to experience any (hazard ratios (HR) = 0.49; 95% confidence interval (CI), 0.30–0.80) and major amputations (HR = 0.53; 95% CI, 0.39–0.73) during follow‐up as overweight individuals. While the amputation risk continued to decrease for higher BMI, amputation‐free survival showed a slight upturn at BMI >40 kg/m2. The association between obesity and amputation risk in our data shows a pattern consistent with “obesity paradox” observed in many health conditions. More research is needed to better understand pathophysiological mechanisms that may explain the paradoxical association between obesity and lower‐extremity amputation (LEA) risk.

Diagnostic accuracy of existing methods for identifying diabetic foot ulcers from inpatient and outpatient datasets

BackgroundAs the number of persons with diabetes is projected to double in the next 25 years in the US, an accurate method of identifying diabetic foot ulcers in population-based data sources are ever more important for disease surveillance and public health purposes. The objectives of this study are to evaluate the accuracy of existing methods and to propose a new method.MethodsFour existing methods were used to identify all patients diagnosed with a foot ulcer in a Department of Veterans Affairs (VA) hospital from the inpatient and outpatient datasets for 2003. Their electronic medical records were reviewed to verify whether the medical records positively indicate presence of a diabetic foot ulcer in diagnoses, medical assessments, or consults. For each method, five measures of accuracy and agreement were evaluated using data from medical records as the gold standard.ResultsOur medical record reviews show that all methods had sensitivity > 92% but their specificity varied substantially between 74% and 91%. A method used in Harrington et al. (2004) was the most accurate with 94% sensitivity and 91% specificity and produced an annual prevalence of 3.3% among VA users with diabetes nationwide. A new and simpler method consisting of two codes (707.1× and 707.9) shows an equally good accuracy with 93% sensitivity and 91% specificity and 3.1% prevalence.ConclusionsOur results indicate that the Harrington and New methods are highly comparable and accurate. We recommend the Harrington method for its accuracy and the New method for its simplicity and comparable accuracy.

Amputations in the diabetic foot and ankle.

Scientific structured foot salvage clinics will provide surgeons with a large population of peripheral vascular insufficiency patients who may someday become candidates for salvage amputation at the foot or ankle level. This article presents the technology of functional amputation levels.