Biomedical subjects
Bruce Sangeorzan
Publications and source records attributed to Bruce Sangeorzan.
Calcaneal lengthening: investigation of deformity correction in a cadaver flatfoot model.
BACKGROUND: Evans showed that lengthening the lateral column by inserting structural bone graft into the anterior calcaneus could correct abduction and valgus deformity in flatfoot. To better understand the mechanism of correction and the three-dimensional effect of this procedure a cadaver study was done. METHODS: Three cadaver flatfoot models were used. Computed tomographic (CT) scans were made of each specimen before and after lengthening. Data from these scans were used to determine the center of volume of the talus, navicular, cuboid, and calcaneus. The angular and translational motions for each bone were determined. RESULTS: On average, relative to the talus, the navicular moved 18.6 degrees of rotation in adduction, 2.6 degrees of rotation in pronation, and 3.4 degrees in plantarflexion. The average translation was 5.6 mm medial, 0.4 mm posterior, and 1.8 mm plantar. The cuboid moved an average of 24.2 degrees of rotation in adduction and lengthening, 13.9 degrees in pronation, and 1.9 degrees in plantarflexion. The average translation was 9.4 mm medial, 2.6 mm distal, and 1.5 mm plantar. The calcaneus moved an average of 4.4 degrees of rotation in adduction, 0.1 degrees of rotation in eversion, and 1.3 degrees of plantarflexion. The average translation was 3 mm medial and 0.7 mm posterior with no plantar translation. CONCLUSIONS: The mechanism of Evans calcaneal lengthening involves adduction and plantarflexion of the midfoot relative to the hindfoot. The cuboid and navicular appear to move as a unit. The shape of the talar head, axis of the subtalar joint, degree of initial deformity, competence of plantar soft tissues, such as the long plantar ligament, and adequate length of the Achilles tendon are important. Knowing what qualitative three-dimensional changes take place allows a better understanding of the mechanics of the procedure and its possible applications.
The efficacy of two methods of ankle immobilization in reducing gastrocnemius, soleus, and peroneal muscle activity during stance phase of gait.
BACKGROUND: Immobilization to limit muscle activity is a common therapeutic and posttreatment event. There are potential time and resource savings if a prefabricated boot can replace a custom applied cast. The purpose of this study was to determine if muscle activity reduction is similar using a fiberglass cast versus a prefabricated (Aircast FoamWalker) boot. METHODS: Surface EMG data were recorded from the gastrocnemius, soleus, and peroneals of 12 normal adults while walking barefoot, in a fiberglass cast with a cast shoe (cast), and while wearing an Aircast FoamWalker (boot). Subjects walked at their self-selected speed for 10 trials in each condition, and the order of barefoot, cast, and boot was randomly assigned. The data were rectified, integrated across stance phase and normalized to a percent of each subject's barefoot mean integrated EMG (iEMG) value. For each muscle, a linear mixed-effects statistical model (subject by trial by condition) was utilized to determine if iEMG activity levels were reduced by immobilization compared to barefoot walking. RESULTS: Activity for all muscles was significantly lower in the boot compared with barefoot (p <.05). The cast iEMG levels were significantly different from barefoot for the soleus and peroneals (p <.05). Gastrocnemius activity was significantly decreased in the boot when compared with the cast (p <.0001). The greater reduction in iEMG levels for the boot indicates that it is superior to a fiberglass cast in reducing gastrocnemius muscle activity during the stance phase of gait. CONCLUSIONS: The data show that a prefabricated boot is as effective as a custom applied cast in reducing soleus and peroneal muscle iEMG during stance phase. The boot was more effective in reducing gastrocnemius activity when compared to the cast. CLINICAL RELEVANCE: This study suggests that a prefabricated boot may be used in place of a custom cast when the goal of treatment is to limit muscle activity of the leg.
The effect of walking speed on peak plantar pressure.
BACKGROUND: Plantar pressure measurements often are used as a tool to evaluate pathologic gait. Previous studies, often done at self-selected walking speeds, have used peak plantar pressure to try to predict ulcer formation, compare surgical outcomes, and evaluate orthotic device efficacy. However, the relationship between walking speed and plantar pressures at specific plantar regions has not been clearly defined. METHODS: Twenty normal subjects walked on a treadmill at six speeds (0.75 to 2.00 m/s). In-shoe peak plantar pressure was measured at five plantar regions and compared across the range of speeds. RESULTS: Walking speed affected peak plantar pressure differently at the five examined plantar regions. The hallux and heel regions had the highest pressures, which increased linearly with faster speeds. The central and medial forefoot pressures initially increased but plateaued at the faster speeds, while the lateral forefoot had the lowest overall peak pressures, which decreased at the faster walking speeds. Therefore, significant quadratic effects were found at the forefoot. Best-fit regression equations defined distinct pressure-speed relationships at each plantar region (p < 0.0001). CONCLUSION: The effect of walking speed on peak plantar pressure varied with plantar region. To achieve more robust peak plantar pressure measurements, walking speed should be controlled. Determining the normal plantar function across a range of speeds can aid in the development of shoes and foot orthoses. The pressure-speed relationships presented in this study can be used as a comparative tool for evaluating the efficacy of clinical interventions for pressure reduction, especially when walking speed changes may confound the outcomes.
The epidemiology of lower-extremity disease in veterans with diabetes.
OBJECTIVE: To describe the epidemiology of lower-extremity complications of diabetes in veterans who are users of the Department of Veterans Affairs (VA). RESEARCH DESIGN AND METHODS: Hospital discharge records for care provided in all VA hospitals in 1998 were obtained. All hospitalizations for lower-extremity ulceration, peripheral vascular procedures, and amputation were analyzed using frequency tables. A diabetes denominator was defined as a veteran with at least three ambulatory care visits with at least one diabetes diagnosis code. Age-specific and total age-adjusted rates of discharge with ulceration, vascular procedures, and amputation were calculated. RESULTS: Veterans with diabetes comprised over half of all hospitalizations for lower-extremity ulceration, one-third of all hospitalizations for peripheral vascular procedures, and two-thirds of all hospitalizations for amputation. The age-specific discharge rate per 1,000 diabetic persons for age 0-64 years, 65-74 years, and 75 years and older for ulceration were 28.4, 31.0, and 37.9; for vascular procedures, the rates were 3.5, 4.4, and 4.4; and for amputation, the rates were 7.3, 9.0, and 10.0, respectively. CONCLUSIONS: Veterans with diabetes comprise a significant proportion of hospitalizations for lower-extremity ulceration, peripheral vascular bypass, and amputation. Age-specific rates of diabetic amputation in veterans are lower than U.S. rates.
Deformity and degeneration in the hindfoot and midfoot joints of the adult acquired flatfoot.
Adult acquired flatfoot is generally characterized by loss of the longitudinal arch, hindfoot valgus, and forefoot abduction, but the precise deformity has not been adequately described at the level of individual joints. Simulated weightbearing CT scans and plain radiographs of 37 symptomatic flat feet were examined in this study. The degree of arthritic degeneration was assessed in the major hindfoot and midfoot joints, and the location of deformity was studied along the medial column of the arch. Moderate to severe degeneration was seen in about one-third of talonavicular, subtalar, and calcaneocuboid joints. The medial column of the arch collapsed through the talonavicular joint in some feet, through the medial naviculocuneiform joint in others, but rarely through both. First tarsometatarsal joint subluxation was a frequent finding as well. In this small series, neither the degree of degenerative arthritis nor the amount of joint deformity was seen to correlate with patient age. Furthermore, no correlation was observed between foot deformity and joint degeneration.