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Biomedical subjects

A Sarmiento

Publications and source records attributed to A Sarmiento.

At least 37 records · Page 2Linked to original sources

Functional bracing for the treatment of fractures of the humeral diaphysis.

BACKGROUND: Nonoperatively treated fractures of the humeral diaphysis have a high rate of union with good functional results. However, there are clinical situations in which operative treatment is more appropriate, and, though interest in plate osteosynthesis has decreased, intramedullary nailing has gained popularity in recent years. We report the results of treating fractures of the humeral diaphysis with a prefabricated brace that permits full motion of all joints and progressive use of the injured extremity. METHODS: Between 1978 and 1990, 922 patients who had a fracture of the humeral diaphysis were treated with a prefabricated brace that permitted motion of adjacent joints. The injured extremities were initially stabilized in an above-the-elbow cast or a coaptation splint for an average of nine days (range, zero to thirty-five days) prior to the application of the prefabricated brace. Orthopaedic residents, supervised by teaching staff, provided follow-up care in a special outpatient clinic. Radiographs were made at each follow-up visit until the fracture healed. RESULTS: We were able to follow 620 (67 percent) of the 922 patients. Four hundred and sixty-five (75 percent) of the fractures were closed, and 155 (25 percent) were open. Nine patients (6 percent) who had an open fracture and seven (less than 2 percent) who had a closed fracture had a nonunion after bracing. In 87 percent of the 565 patients for whom anteroposterior radiographs were available, the fracture healed in less than 16 degrees of varus angulation, and in 81 percent of the 546 for whom lateral radiographs were available, it healed in less than 16 degrees of anterior angulation. At the time of brace removal, 98 percent of the patients had limitation of shoulder motion of 25 degrees or less. We were unable to follow most of the patients long-term, as they did not return to the clinic once the fracture had united and use of the brace had been discontinued. CONCLUSIONS: Functional bracing for the treatment of fractures of the humeral diaphysis is associated with a high rate of union, particularly when used for closed fractures. The residual angular deformities are usually functionally and aesthetically acceptable. The present study illustrates the difficulties encountered in carrying out long-term follow-up of indigent patients treated in charity hospitals that are affiliated with teaching institutions. These difficulties are also becoming common with patients insured under managed-care organizations and are frequent in our peripatetic population.

Adult↗

Tuberculosis in the urban poor settlements in the Philippines.

SETTING: Urban poor settlements in the Philippines. OBJECTIVE: To determine the magnitude of the tuberculosis problem in urban poor settlements in comparison with urban areas studied in the Nationwide Tuberculosis Prevalence Survey. STUDY DESIGN AND METHOD: A multistage cluster survey of BCG scar, tuberculin test, chest radiography and sputum examination for bacillary disease, in urban poor areas. RESULTS: The prevalences of culture-positive and smear-positive tuberculosis were 17.5 +/- 2.3 (95% CI 13.3-22.4) and 7.9 +/- 2.3 per thousand (95% CI 2.611.5), respectively. Extrapolated to the total population, the rates in the urban poor settlements were 12.4 +/- 1.7 (95% CI 9.6-16.2) and 5.6 +/- 1.6 per thousand population (95% CI 1.3-8.3), respectively. The prevalence of active pulmonary tuberculosis in subjects aged 10 years or more was 66 +/- 5.6/1000 (95% CI 55-77). The BCG vaccination rate was 72%. The overall prevalence of tuberculosis infection was 66%, and 39% in those aged 5-9 years, corresponding to an annual risk of infection (ARI) of 6.5%. CONCLUSION: The problem of tuberculosis was substantial in the urban poor settlements, and was appreciably worse than that in the general urban population.

Adolescent↗

BCG coverage and the annual risk of tuberculosis infection over a 14-year period in the Philippines assessed from the Nationwide Prevalence Surveys.

SETTING: A prevalence survey of tuberculosis (TB) infection was undertaken in the Philippines, a developing country in the Western Pacific region. OBJECTIVE: To determine the bacille Calmette Guerin (BCG) vaccination rate, the prevalence of TB infection and the annual risk of TB infection (ARTI). METHODS: A nationwide stratified multi-stage cluster survey of 21,960 individuals. BCG scar verification and tuberculin test were performed on those aged > or =2 months. The ARTI was calculated using the prevalence rates of TB infection in children aged 5-9 years. RESULTS: BCG scars were noted in 66% of the study population. The prevalence of TB infection was 63.4% among unvaccinated individuals. The prevalence rate was higher in males in both urban and rural areas. With both sexes combined, urban and rural communities had similar prevalence rates. In children aged 5-9 years, the prevalence rate was 16.1% (males 17.4%, females 14.9%), corresponding to an ARTI of 2.3% (males 2.5%, females 2.1%). CONCLUSION: BCG coverage increased substantially between 1981-1983 and 1997. The ARTI, however, was virtually unchanged, indicating that morbidity due to TB continued to be high.

Adolescent↗

Environmental factors associated with blood lead levels in Venezuelan children.

A preliminary study explored the relative contribution of residential sources of lead exposure on mentally challenged children who attend "special education" institutions (GI) compared to a group of age and sex matched school children (G2). We captured descriptive information and analyzed demographic variables, personal and household information, medical effects, environmental exposure factors, and children habits. Home paint, dust, soil, and water sampling was conducted and blood lead (BPb) levels determined. Eighteen G1 and 20 G2 children were studied. The mean G1 BPb was 16.9 +/- 7.9 microg/dl and was significantly higher than that in G2. Fifty percent of G1 children had PbB >20 microg/dl and 72.2% were >10 microg/dl. Low muscular strength, decreased osteotendinose reflexes, fine and gross motricity, deficient equilibrium, and hipotonic muscular tone coincided with >18 microg/dl BPb levels. In 61.1% of G1 homes paint lead levels were higher than permissible levels and 33.3% had dust lead exceeding that level. The high BPb levels in G1 probably resulted from ingestion of household paint, dust, and soil via "hand-to-mouth" activity. Environmental exposure to lead can be an important source of lead intake by infants and children and could affect neurological development. This study provides new insights currently unavailable for these children in Venezuela.

Anthropometry↗

Bacillary disease and health seeking behavior among Filipinos with symptoms of tuberculosis: implications for control.

SETTING: Urban and rural communities and urban poor settlements in the Philippines. OBJECTIVE: To determine bacillary disease and action taking among individuals with symptoms of tuberculosis (TB), and to analyze their implications for TB control. STUDY DESIGN AND METHOD: Subjects aged 20 years and older were interviewed in the 1997 nationwide stratified multi-cluster survey. Sputum acid-fast smears and cultures were done in subjects with abnormal screening chest radiographs. RESULTS: Individuals with TB symptoms comprised 18.1% of the population studied. The prevalence of bacillary disease was 39/1000 in symptomatic subjects compared to 13/1000 in asymptomatic subjects. Symptom screening had a 14.3% positive predictive value and a 91.4% negative predictive value for bacillary disease. Significantly more symptomatic than asymptomatic subjects attended chest radiographic screening during the survey. However, in response to their symptoms, the majority (43.0%) took no action or self medicated (31.6%), while 11.8% consulted a private practitioner, 7.5% a public health center, 4.4% a hospital, and 1.7% a traditional healer. CONCLUSION: Sputum smear examination after symptom screening was acceptable for case finding. The health seeking behavior of subjects with TB symptoms was inappropriate. A health education program and public-private collaboration in directly observed therapy, short course (DOTS) are essential for TB control in the Philippines.

Adult↗

Comparison of healing process in open osteotomy model and closed fracture model.

OBJECTIVE: Comparison of the healing process in open osteotomy and closed fracture models that were used to study fracture healing. DESIGN: Randomized, prospective study in experimental animals, with a recovery duration of two and four weeks. SETTING: Unrestricted cage activity with weight bearing as tolerated. ANIMALS: Thirty-four skeletally mature, female New Zealand White rabbits. INTERVENTIONS: Closed fractures and open osteotomies of the tibial diaphysis were reduced and immobilized with four-pin, double-bar external fixators. MAIN OUTCOME MEASUREMENTS: Callus circumference was measured with a tape measure, bridging callus was assessed on biplane radiographs and evaluated histologically, and torsional stiffness and maximum torque were measured. RESULTS: Periosteum damage was more severe and hematoma formation was smaller in the osteotomy model, resulting in a delay in biological healing and restoration of the biomechanical properties. CONCLUSIONS: Investigators should consider the difference between the closed fracture and open osteotomy models when selecting an animal model to investigate fracture healing.

Animals↗

Deterministic transport in ratchets.

We present the deterministic transport properties of driven overdamped particles in a simple piecewise-linear ratchet potential. We consider the effects on the stationary current due to local spatial asymmetry, time asymmetry in the driving force, and we include the possibility of a global spatial asymmetry. We present an extremely simple scheme for evaluating the current that is established on the ratchet within an "adiabatic" approximation, and compare the results with exact numerical integration of the process.

Journal Article↗

Enhanced pulse propagation in nonlinear arrays of oscillators.

The propagation of a pulse in a nonlinear array of oscillators is influenced by the nature of the array and by its coupling to a thermal environment. For example, in some arrays a pulse can be speeded up while in others a pulse can be slowed down by raising the temperature. We begin by showing that an energy pulse (one dimension) or energy front (two dimensions) travels more rapidly and remains more localized over greater distances in an isolated array (microcanonical) of hard springs than in a harmonic array or in a soft-springed array. Increasing the pulse amplitude causes it to speed up in a hard chain, leaves the pulse speed unchanged in a harmonic system, and slows down the pulse in a soft chain. Connection of each site to a thermal environment (canonical) affects these results very differently in each type of array. In a hard chain the dissipative forces slow down the pulse while raising the temperature speeds it up. In a soft chain the opposite occurs: the dissipative forces actually speed up the pulse, while raising the temperature slows it down. In a harmonic chain neither dissipation nor temperature changes affect the pulse speed. These and other results are explained on the basis of the frequency vs energy relations in the various arrays.

Journal Article↗

Thromboembolic prophylaxis with use of aspirin, exercise, and graded elastic stockings or intermittent compression devices in patients managed with total hip arthroplasty.

BACKGROUND: Prophylaxis against pulmonary embolism as a complication of total hip arthroplasty remains controversial. Our experience suggests that an inexpensive protocol of prophylaxis that includes aspirin and exercise is effective. METHODS: We investigated the effectiveness of aspirin, a program of intraoperative and postoperative exercises, and graded elastic stockings or intermittent compression devices as prophylaxis against thromboembolic disease in a series of 1267 patients who had had 1492 total hip arthroplasties. All of the operations were done through a posterior approach. For the purpose of this review, the duration of follow-up was limited to a minimum of three months. No patient was lost to follow-up. Any thromboembolic complications that may have occurred after the third postoperative month were not considered to be related to the operation and were not recorded. RESULTS: A fatal pulmonary embolism occurred after two arthroplasties (0.13 percent), a nonfatal pulmonary embolism was diagnosed after fourteen (0.94 percent), and deep venous thrombosis developed after fifteen (1.01 percent). Regional (epidural) anesthesia was used for 1099 arthroplasties (73.7 percent), and general anesthesia was used for 393 procedures (26.3 percent). A fatal pulmonary embolism occurred after two (0.18 percent) of the 1099 arthroplasties that had been performed with regional anesthesia and after none that had been performed with general anesthesia (chi square = 0.22; p > 0.05). A nonfatal pulmonary embolism occurred after two procedures (0.18 percent) that had been done with regional anesthesia and after twelve (3.05 percent) that had been done with general anesthesia (chi square = 25.3; p < 0.001). Deep venous thrombosis was diagnosed after seven procedures (0.64 percent) that had been performed with regional anesthesia and after eight (2.04 percent) that had been performed with general anesthesia (chi square = 5.45; p < 0.025). We detected a significant difference between men and women with respect to the rate of nonfatal pulmonary embolism (chi square = 4.36; p < 0.05). With the numbers available, we found no significant differences between the 774 arthroplasties (51.9 percent) in patients who had worn graded elastic stockings and the 718 arthroplasties (48.1 percent) in patients who had used intermittent compression devices, between the 774 arthroplasties (51.9 percent) that had been performed in Florida and the 718 (48.1 percent) that had been done in California, or between the 1313 primary arthroplasties (88 percent) and the 179 revision arthroplasties (12 percent), with regard to the prevalence of fatal pulmonary embolism, nonfatal pulmonary embolism, or deep venous thrombosis (p > 0.05 for all comparisons). In summary, we found that the type of compression (graded elastic stockings or intermittent compression devices), the geographic location (California or Florida), and the type of operation (primary or revision) had no significant effect, with the numbers available, on the rate of thromboembolic complications. Compared with general anesthesia, the use of regional anesthesia was associated with a significantly lower rate of nonfatal pulmonary embolism (p < 0.001) and deep venous thrombosis (p < 0.025). Both patients who had a fatal pulmonary embolism had had regional anesthesia (p > 0.05). CONCLUSIONS: This inexpensive method of prophylaxis against thromboembolic disease after total hip arthroplasty, which was based primarily on the use of aspirin as the pharmacological agent and the performance of intraoperative and postoperative exercises, produced good clinical results.

Arthroplasty, Replacement, Hip↗

Functional fracture bracing.

Functional bracing is an effective therapeutic modality in the management of selected fractures of the tibia, humerus, and ulna, particularly low-energy injuries. In the case of tibial fractures, it is applicable only to reduced transverse fractures and to axially unstable fractures with an acceptable degree of shortening. The rate of union of tibial fractures after functional bracing is approximately 97%. The initial shortening noted with closed tibial fractures rarely increases with weight bearing. Shortening has been reported to be as little as 12 mm in 95% of patients, with angulation of 8 degrees in 90%. Such minimal shortening and angulation do not affect functional results. In closed and type I open diaphyseal humeral fractures treated with functional braces, the nonunion rate is approximately 3%. Most of the reported residual angular deformities have been functionally and cosmetically acceptable. For isolated ulnar fractures, the nonunion rate is approximately 2%. Functional fracture bracing is predicated on the premise that motion at the fracture site encourages osteogenesis. The method is applicable only to selected fractures, and it is necessary to have a clear understanding of its rationale, indications, and technique.

Braces↗

Mechanism of failure in hips with an uncemented, all polyethylene socket.

The outcome of 32 patients with 33 primary total hip replacements performed using noncemented uncoated polyethylene acetabular cups (RM cup) with cemented titanium alloy monoblock stems (STH-2 stem) was reviewed. At a mean followup of 6.3 years (range, 6 months-10 years), the failure rate was 57%, more than 14 times higher than the rate typically seen with cemented polyethylene acetabular cups used with the STH stem. Failure was characterized by rapidly progressive acetabular or femoral osteolytic lesions that resulted in extensive bone loss, often in patients who had no symptoms. In addition to the debris that typically is generated by a metal on plastic bearing couple, an abundance of polyethylene particles of submicron size were produced at the cup-bone interface. Tissues retrieved from areas of osteolysis revealed the presence of intracellular submicron polyethylene particles in macrophages. It is recommended that patients with no symptoms who have RM noncemented, uncoated acetabular cups be followed up yearly and undergo early revision surgery when faced with osteolysis to prevent extensive bone loss.

Acetabulum↗

The 1997 Nationwide Tuberculosis Prevalence Survey in the Philippines.

SETTING: The Philippines is a developing country where tuberculosis (TB) remains a significant public health problem. OBJECTIVE: To determine the prevalence of TB as a basis for setting the targets of the National Tuberculosis Control Program. STUDY POPULATION AND METHODS: A multi-stage cluster survey of a random sample of 21960 subjects from 36 clusters nationwide was undertaken from 2 April to 31 July 1997. BCG scar verification and tuberculin testing was performed for subjects aged 2 months and over, and chest radiography screening was done on subjects 10 years and older. Sputum samples were collected from individuals who were initially assessed to have abnormal chest radiographs to determine the prevalence of bacillary tuberculosis. Acid-fast smear by modified Kinyoun's technique and culture on Löwenstein Jensen were done to demonstrate Mycobacterium tuberculosis. RESULTS: The prevalence of active pulmonary TB was 42/1000 population. The prevalence of culture-positive and smear-positive cases was 8.1 and 3.1/1000, respectively. The prevalence was similar in urban and rural areas. CONCLUSION: Morbidity from TB remains high. Allowing for methodological differences from the survey in 1981-1983, the prevalence of active pulmonary TB was unchanged. There was only a minimal decrease, of 37% for smear-positive cases and 25% for culture-positive cases, in the 14-year interval.

Adolescent↗

Cartilage changes caused by a coronal surface stepoff in a rabbit model.

Coronal stepoffs of 0.5 mm (equal to the cartilage height) were created on the medial femoral condyles of adult, skeletally mature rabbits as a model for articular surface incongruity. After 3, 6, 12, and 24 weeks, tissue was analyzed histologically using hematoxylin and eosin and Safranin O staining, autoradiographs were made of the femoral condyles, and immunohistologic analysis was done for 3-B-3(-) and 7-D-4 chondroitin sulfate epitopes. An overlapping flap from the high toward the low side and an increase of the cartilage height on the low side of the defect were observed as permanent features of adaptation throughout the entire followup. Significant degeneration was not seen around the lesion or in the tibial cartilage opposing a stepoff defect. Autoradiography showed a three-phase response to the lesion: an early increase in radiolabeled sulfate (35SO4) uptake, a sharp decline of 35SO4 uptake, and finally a late recovery of the autoradiographic signal indicating partial recovery of proteoglycan synthetic activity. After an early increase, immunohistologic analysis for 3-B-3(-) showed a subsiding tendency by 24 weeks, and the staining with 7-D-4 remained elevated uniformly in the vicinity of the lesion. A rabbit femoral stepoff defect with an offset of 0.5 mm may remodel and not lead to degeneration within the first 6 months after injury in a stable joint.

Adaptation, Physiological↗

Isolated ulnar shaft fractures treated with functional braces.

OBJECTIVE: To report the results from functional bracing of isolated ulnar shaft fractures. DESIGN: Retrospective review. SETTING: Two university hospitals. PATIENTS: Isolated ulnar shaft fractures in 444 patients were stabilized in functional braces that permitted full range of motion of all joints. INTERVENTION: Prefabricated braces that extended from below the elbow to above the wrist were applied within the first week after the initial injury. OUTCOME MEASURES: Union of the fracture, fracture angulation, and final range of motion of the forearm were evaluated. RESULTS: Two hundred eighty-seven patients were available for follow-up (65 percent). Union took place in 99 percent of the fractures. Shortening of the ulna averaged 1.1 millimeters (range 0 to 10 millimeters). Final radial angulation averaged 5 degrees (range 0 to 18 degrees). Dorsal angulation averaged 5 degrees (range 0 to 20 degrees). Average loss of pronation was greatest in fractures of the proximal third of the ulna, averaging 12 degrees. Fractures in the distal third averaged a loss of 5 degrees of pronation. CONCLUSIONS: Functional bracing is a viable therapeutic alternative in the management of isolated ulnar shaft fractures. It is associated with a 99 percent union rate and good to excellent functional results in more than 96 percent of patients.

Adult↗

The influence of active shear or compressive motion on fracture-healing.

The effects of interfragmentary sliding (shear) motion, axial motion, and locked external fixation on the healing of mid-tibial closed fractures were studied in fifty-six skeletally mature New Zealand White rabbits. The fractures were fixed with use of a four-pin, double-bar frame and were allowed to heal for either two or four weeks. Four experimental conditions were evaluated: transverse and oblique fractures treated with a locked external fixator (Groups 1 and 3, respectively), transverse fractures treated with an axially telescoping fixator (Group 2), and oblique fractures treated with a sliding oblique fixator (Group 4). The maximum interfragmentary motion, recorded in vivo with an electronic motion sensor that was attached to the fixator, was 0.6 millimeter in Group 2 during the first week and then declined rapidly. In contrast, the motion in Group 4 exceeded 1.5 millimeters during the first week. The circumference of the callus in Group 4 was 11 to 23 per cent greater than that in the other groups at both two and four weeks (p < or = 0.02). At two weeks, torsional stiffness, strength, and energy absorption were comparable among Groups 1, 2, and 3. The increase in healing was most rapid for Group 4; by four weeks, the torsional strength and energy to failure of the fractures in Group 4 exceeded those in the other groups (p < or = 0.025) and reached or exceeded those of intact bone. Apparently, oblique sliding (shear) motion promoted greater cartilage differentiation and expansion of the peripheral callus than did axial motion or locked external fixation.

Animals↗