Lengthening of the Achilles tendon in diabetic patients who are at high risk for ulceration of the foot.

BACKGROUND: The purpose of this study was to determine the degree to which pressure on the plantar aspect of the forefoot is reduced following percutaneous lengthening of the Achilles tendon in diabetic patients who are at high risk for ulceration of the foot. METHODS: Ten diabetic patients who had a history of neuropathic plantar ulceration of the forefoot were enrolled in a laboratory gait trial. A repeated-measures design and a computer analysis of force-plate data were used to examine dynamic pressures on the forefoot, with the patient walking barefoot, immediately before percutaneous lengthening of the Achilles tendon and at eight weeks afterward. Although the wound in each patient had healed at least one month before the operation, we considered the patients to be at high risk for ulceration because they had had an ulcer previously. RESULTS: The mean peak pressure (and standard deviation) on the plantar aspect of the forefoot decreased significantly from 86+/-9.4 newtons per square centimeter preoperatively to 63+/-13.2 newtons per square centimeter at eight weeks postoperatively (p<0.001). Commensurately, the mean dorsiflexion of the ankle joint increased significantly from 0+/-3.1 degrees preoperatively to 9+/-2.3 degrees at eight weeks post-operatively (p<0.001). CONCLUSIONS: The results of this study suggest that peak pressures on the plantar aspect of the forefoot are significantly reduced following percutaneous lengthening of the Achilles tendon in diabetic patients who are at high risk for ulceration of the foot. We are unaware of any other reports in the medical literature that describe such findings. These data may lend support to studies that have indicated that this procedure should be used as an adjunctive therapeutic or prophylactic measure to reduce the risk of neuropathic ulceration.

An examination of plantar pressure measurements to identify the location of diabetic forefoot ulceration.

The purpose of this study was to evaluate pressure-time parameters on the sole of the foot in order to predict sites of pathology in diabetics. Mid-gait walking steps from 36 subjects diagnosed with diabetes and ulceration to the forefoot were analyzed using the Pedar in-shoe pressure analysis system. The time that weight was loaded on the hallux and lesser digits was found to be significantly shorter on the feet with ulceration compared to those without. A combination of five pressure measure reports could significantly differentiate between the three common locations of forefoot ulcerations. The significant pressure measure reports were the pressure-time integral measured over the whole foot and pressure-time integral and peak pressure measured separately at the first and combined lesser metatarsophalangeal joint regions. A preliminary model was developed using discriminate analysis that was accurate to 72.7% in identifying the location of the subjects' ulceration. Sensitivity and specificity formulas were calculated to demonstrate the diagnostic value of the model. The model accurately identified ulceration locations to a sensitivity of 83% and a specificity of 69%. Further refinement and testing is underway to refine the model to develop a screening tool to identify the site of potential foot ulceration and to prevent it and its sequelae of lower limb ulceration in the diabetic population.

Use of a computerized digital camera in podiatric medical practice.

Multimedia technology was once rarely found outside the realm of commercial production studios or in elaborate computer games. However, with the addition of only a few simple accessories, recent advances have made this technology readily available to the podiatric medical practitioner on a desktop office computer. The role that the application of multimedia technology using a computerized digital camera can play in a podiatric medical practice--including in such areas as record keeping, outcome measurement, patient education, interdisciplinary communications, and practice-management tools--is discussed.

Total contact casts and removable cast walkers. Mitigation of plantar heel pressure.

The purpose of this study was to compare the ability of various modalities to reduce pressure in the plantar heel. Twenty-five patients with grade 1A plantar foot ulcerations were evaluated; a repeat measures design comparing plantar pressure was used to evaluate the total contact cast, the Aircast pneumatic walker, the DH pressure relief walker, and depth-inlay shoes. The total contact cast reduced pressure significantly better than the other modalities; however, its pressure reduction was only 33% less than a baseline sneaker. All other modalities reduced significantly more pressure than the depth-inlay shoe. The DH walker had a significantly lower pressure-time integral than other modalities. These data indicate that, while the total contact cast appears to be effective compared with other modalities, the role that limitation of transverse motion of the fat pad on compression at heel strike has yet to be fully explained.

Instrumentation considerations of a clinical and a computerized technique for the measurement of foot angles.

Measurement of the foot angles either directly from the patient, from video images, or from radiographs is integral to podiatric clinical practice to confirm diagnoses and to plan, prescribe, and monitor treatment protocols. The reliability, precision, and accuracy involved in any measured value limits the validity and usefulness of the measurement to optimal patient management. Studies are described that ensured the accuracy and validity of the standard clinical tool, the universal goniometer (UG), by applying a calibration protocol. These same calibration angles were then measured by a computer-assisted human movement analysis system, the Ariel Performance Analysis System (APAS). The APAS was found to overestimate consistently the UG angular measures by less than 1 degree and this amount of error was considered clinically irrelevant. The angular results obtained by a clinician and a technician using the APAS on two separate days were tested and were found to be comparable and reliable to within 1 degree, and thus the analysis was deemed to be of excellent reliability and precision. The study found that clinicians could establish the accuracy and validity of their instruments by means of simple calibration, and that computer measures could be repeated on patients by a clinical or a technician. The simple calibration procedure described will assist the clinician to ensure that the measures obtained in the clinical setting have minimal measurement error and that the values can be confidently used to make decisions and draw clinical inferences.

The benefit of electrical stimulation to enhance perfusion in persons with diabetes mellitus.

The purpose of this study was to evaluate the effect of galvanic electrical stimulation on vascular perfusion in diabetic patients. Nineteen subjects with diabetes were enrolled. Eleven subjects (57.9%) were diagnosed with impaired peripheral perfusion based upon their initial transcutaneous oximetry values (< 40 mm Hg). The subjects were studied over a 2-day period. On the 1st day, one foot was electrically stimulated for four 60-minute periods by an external electrical stimulation device. Vascular perfusion of both feet was assessed before and after the sessions of electrical stimulation. On the 2nd day, no electrical stimulation was applied and noninvasive vascular measurements were repeated. For the 1st hour, transcutaneous oxygen pressure was measured continuously during stimulation at the lateral aspect of the leg. Subsequently, perfusion between the periods of stimulation was measured on the dorsum of the foot with both transcutaneous oximetry and laser Doppler flowmetry after each stimulation period. In the group with impaired peripheral perfusion, a significant rise in tissue oxygenation as compared to the control measurements was measured during the first 5 minutes of stimulation (p < .040). For those without vascular disease (TcpO2 > 40 mm Hg) however, there was not a significant increase compared to baseline (p = .280). After the periods of stimulation, the stimulated feet did not show any higher perfusion levels than the control feet. Patterns in perfusion during the day, as measured by laser Doppler flowmetry, were similar in the tested feet and in the controls. These data suggest that external subsensory electrical stimulation induces a transient rise in skin perfusion in persons with diabetes and impaired peripheral perfusion.