Biomedical subjects

S C Huang

Publications and source records attributed to S C Huang.

At least 163 records · Page 9Linked to original sources

PubMed1997

Comparison of bone transport and bone graft methods in the experimental treatment of bone defects.

Large segmental bone defects due to trauma, infection or tumor resection are difficult to treat. To compare the effects of a bone transport technique with various bone graft methods in treating this problem, an animal model with a designed mini external fixator to accomplish the bone transport was established. New Zealand white rabbits weighing 3 kg were divided into five groups. A 2 cm bone defect was created in the left hind tibia of each rabbit, then stabilized with an external fixator. In the control group, no treatment was given. In the autograft group, an autogenous bone segment was repositioned after removal of the periosteum. In the double osteotomy group, the tibial shaft was doubly osteotomized at the upper and lower level with preservation of vascular supply to the middle segment. In the allograft group, a deep-frozen allograft was put into the defect and in the bone transport group, the middle segment of the tibia was transported downward gradually beginning 1 week after the osteotomy. The rabbits had weekly radiographic examinations and were killed 3 months postoperatively. Rabbits with fractures, severe infection, incomplete osteotomy or that died were excluded from analysis. There were 12 rabbits remaining in each group. Results were evaluated by radiographic and torsion tests. Rabbits in the double osteotomy group had the best results, followed by the autograft bone transport, allograft and control groups. Fractures at the distal pin-bone interface occurred more often in control and bone transport groups than other groups. Incomplete osteotomy and problems at the docking site were specific to the bone transport group. The results of this study suggest that the bone transport technique may be used to treat large bone defects, but is associated with significant morbidity.

Animals↗

PubMed1997

Surgical treatment of clubfoot deformity in arthrogryposis multiplex congenita.

Clubfoot deformity in arthrogrypotic patients is difficult to correct, and its recurrence rate is high. We retrospectively reviewed 37 clubfeet in 20 patients with arthrogryposis multiplex congenita who were treated from 1984 to 1993. There were 11 males and nine females. Bilateral involvement was seen in 17 patients and unilateral involvement in three. The mean age at the initial surgery was 2.5 years (range 4 mo to 25 yr). Soft tissue release alone was performed on 33 feet. Primary talectomy was done on both feet of one other patient. The remaining patient (two feet) underwent triple arthrodesis. Recurrence or residual deformities were seen in 18 feet with soft tissue release, among which 12 feet underwent secondary surgeries including soft tissue release, osteotomy, talectomy and connection with Ilizarov apparatus. After the secondary surgery, four of the 12 feet still had deformities. One foot had a third surgery. Achilles tendon lengthening and osteotomy. Twenty-six feet were rated as having good results (plantigrade, painless and without obvious deformity), seven were rated fair (residual deformity requiring secondary procedures) and four had poor results (persistance or recurrence of clubfoot). Despite a high recurrence rate, clubfoot deformity in arthrogrypotic patients can be treated first with radical soft tissue release when the patient is less than 1 year of age. If the foot deformity is persistant or recurs, talectomy can achieve a plantigrade foot. Triple arthrodesis should be reserved for patients with a mature bony structure.

Arthrogryposis↗

PubMed1997

Valgus osteotomy for congenital coxa vara.

Congenital coxa vara is a rare disease which can result in a significant disability if untreated or improperly treated. In this retrospective review of eight patients (12 hips) with congenital coxa vara, there were five boys and three girls. Four patients had bilateral involvement and four had unilateral involvement. At the time of surgery, the average age was 7.9 years. All patients underwent valgus intertrochanteric osteotomy with wires or blade-plates for fixation. The mean Hilgenreiner-epiphyseal angle was 75 degrees before surgery and improved to 25 degrees after surgery. The mean neck-shaft angle improved from 95 degrees to 137 degrees immediately after the osteotomies and was 125 degrees at the final follow-up. At a minimum two year follow-up only three hips in three patients maintained more than 80% correction. These three patients all had developmental coxa vara. The acetabular depth improved significantly in the patients with developmental coxa vara, especially in two patients (three hips) who underwent surgery before 6 years of age. Closure of physeal plates was found in three patients (five hips) before surgery and occurred in two patients (two hips) after surgery. After surgery, only two patients had persistent soreness. One patient walked with a limp, and the other, with multiple epiphyseal dysplasia had significant leg length discrepancy. Our results show that valgus osteotomy can correct varus deformities of the proximal femur and improve function. If performed early, it can also prevent the development of hip dysplasia in patients with developmental coxa vara. However, the response of acetabular development was variable in patients with coxa vara due to skeletal dysplasia, despite valgus osteotomy.

Adolescent↗

PubMed1997

Triple innominate osteotomy and rotational acetabular osteotomy in the treatment of congenital hip dysplasia.

Congenital hip dysplasia is a developmental disease which predisposes patients to osteoarthritis of the hip. We compare the results and complications of triple innominate osteotomy and rotational acetabular osteotomy in the treatment of this disease. Between 1984 and 1992, 27 patients with 30 dysplastic hips received reconstructive procedures at National Taiwan University Hospital. Fourteen patients (16 hips) with a median age of 18 years were treated by triple innominate osteotomy. Nine of 16 hips had concomitant femoral osteotomy. Another 13 patients (14 hips) with a median age of 24 years were treated by rotational acetabular osteotomy. We compared the radiologic and functional results, complications and satisfaction of the patients in these two groups. Patients who underwent rotational osteotomy showed more correction in roof obliquity than patients who had triple innominate osteotomy. The functional results when evaluated by Harris scores, were better in patients who had triple innominate osteotomy than rotational osteotomy. Complications included one resubluxation of the hip in each group as well as one perforation of the hip joint and one pin break and nonunion at the osteotomy site in the rotational osteotomy group. Patients who had triple innominate osteotomy were more satisfied with the results. With proper selection of patients and accurate performance of the procedure, both triple innominate osteotomy and rotational osteotomy may be used effectively for the treatment of congenital hip dysplasia. However, in our study, patients who underwent rotational osteotomy had better anatomic correction, while those who underwent triple innominate osteotomy had better functional results.

Acetabulum↗

PubMed1997

Femoral lengthening: callotasis with Ilizarov external fixator alone and with intramedullary locking nail.

Callus distraction (callotasis) has improved the results of limb lengthening and has decreased complication rates. Unfortunately, this technique requires a long time in an external fixator device to allow bone regeneration and consolidation, especially in adults. We retrospectively compared the results and complications of two groups of patients who underwent femoral lengthening by means of callotasis with the Ilizarov external fixator. Group I underwent callotasis alone, and group II underwent callotasis with an intramedullary locking nail. Group I consisted of 14 patients, with a median age at surgery of 24.3 years. Group I etiologies were trauma in seven patients, congenital disorders in four and sequelae of poliomyelitis in three. Group II consisted of seven patients, with a median age at surgery of 22.4 years. The etiologies in group II were trauma in five patients and congenital disorders in two. In group I, the median gain in length was 4 cm. The median time in the external fixator was 218 days. The median time index of external fixation was 50 days/cm. Complications included four pin tract infections, one incomplete corticotomy, one refracture and one flexion contracture after removal of the external fixator. In group II, the median gain in length was 4.8 cm, and the median time in the external fixator was 70 days. The median time index of external fixation was 14 days/cm. There were no major complications except one distal screw backout, which did not impair the final outcome. We conclude that femoral lengthening by callotasis with combined Ilizarov external fixator and intramedullary locking nail can significantly shorten the treatment in the external fixator period, with good results and low complication rates in adults.

Adolescent↗

PubMed1997

Pulmonary vascular obstructive disease and hemoptysis in a child with tetralogy of Fallot and patent ductus arteriosus.

Tetralogy of Fallot (TOF) and patent ductus arteriosus complicated by pulmonary vascular obstructive disease (PVOD) and hemoptysis in a 5-year-old girl are described. The echocardiogram was typical of TOF, as well as ductus arteriosus and right aortic arch. Cardiac catheterization revealed a pulmonary vascular resistance of 44 hybrid resistance units, and the pulmonary-to-systemic resistance ratio was 1.4. Diagnosis of PVOD was made by cardiac catheterization. Angiography revealed a bronchial artery arising from the left subclavian artery. PVOD itself, rupture of a bronchial artery or both, were considered the contributory causes of hemoptysis in this patient.

Child, Preschool↗

PubMed1997

Compartment model for measuring myocardial oxygen consumption using [1-11C]acetate.

UNLABELLED: Although [1-11C]acetate has been validated as a PET tracer for myocardial oxygen consumption (MVO2) in animals and humans, mono- and biexponential fitting of the tissue time-activity curve yields only estimates of MVO2. This study attempts to develop and validate a simple tracer kinetic model in vivo for estimation of regional MVO2. METHODS: Twenty-seven experiments were performed in 12 anesthetized dogs with [1-11C]acetate and serial PET images under different MBF and MVO2 (baseline, ischemia, xylazine, dobutamine and dipyridamole). Estimates of MVO2 were obtained from dynamic [1-11C]acetate PET and model fitting. MBF was measured by radiolabeled microspheres, and MVO2 was calculated by the Fick method using arterial and coronary blood samples. RESULTS: The proposed model fitted equally well for all study conditions with a multiple correlation coefficient of 0.985 +/- 0.026. Estimated MVO2 correlated linearly with measured MVO2 (y = 0.033 + 0.690x, r = 0.92, s.e. of estimates = 0.020). CONCLUSION: This study indicates that MVO2 can be assessed with PET and [1-11C]acetate over a wide range with a simple tracer kinetic model.

Acetates↗

PubMed1997

Electrophysiologic evaluation of neuromuscular functions during limb lengthening by callus distraction.

We investigated the effects of different rates and extents of lengthening on the affected nerves and muscles in callus distraction, in a rabbit tibial model. Electrophysiologic evaluations measuring the motor nerve conduction velocity of the peroneal and tibial nerves, and compound muscle action potentials of the anterior tibialis and gastrocnemius muscle were performed sequentially on rabbits whose left legs were lengthened at different rates and to different extents over a 5-month period after surgery. We found that neuropathies of the peroneal nerves developed earlier and were more severe than those of tibial nerves, especially when the rate of lengthening was over 2 mm per day, or when the extent of lengthening was over 20% of the leg length at a lengthening rate of 1 mm per day. When the nerve damage was mild, there was a slow recovery of nerve function with time. The anterior tibialis muscle exhibited earlier and more severe damage than the gastrocnemius muscle during lengthening, especially when the rate of lengthening was over 2 mm per day, or when the extent of lengthening was over 20% of leg length. Elevated serum creatine kinase levels also indicated muscle damage after lengthening, especially in cases of high lengthening rates and long extent of lengthening. We conclude that nerves and muscles may have the same optimal rate of lengthening as bones, (1 mm per day). However, the extent of lengthening still has a limit of 20% or less of the total leg length. Electrophysiologic evaluation measuring the motor nerve conduction velocity and compound muscle action potential can serve as a tool for early detection and for long-term monitoring of neurologic dysfunction.

Action Potentials↗

PubMed1997

Polydactyly of the foot: manifestations and treatment.

Polydactyly of the foot is not an uncommon foot problem. However, it is not well understood and not often reported. Its clinical manifestations vary, as do treatment methods and results. During the period of 1979 to 1994, 54 children with polydactyly of 65 feet were treated in our clinic. Bilateral involvement was seen in 11 patients, and six had accompanying polydactyly of the hand. By Blauth and Olason's classification, duplication of the fifth ray (43 feet) was most common, followed by first ray duplication (20 feet) and other ray duplication (2 feet). A rudimentary form was found in one foot. Polysyndactyly was present in 18 feet. Hallux varus was the most common associated problem and was present in seven feet. Surgery for both cosmetic and functional purposes was performed in 38 patients (44 feet). Treatment included excision of the extra toe and reconstruction of the soft tissue around the remaining toe, of which the alignment was restored in cases of deviation. Results were evaluated with Phelps-Grogan's protocol; 39 feet (88%) were classified as having excellent results, two (5%) had good, and three (7%) had poor results. Postoperative complications included residual hallux varus in three feet with polydactyly of the first ray, and unpleasant surgical scars in another two. We conclude that polydactyly of the foot should be treated individually, depending on classification. Special attention should be paid to complex first ray polydactyly.

Adolescent↗

PubMed1997

Role of tissue specific alternative pre-mRNA splicing in the differentiation of the erythrocyte membrane.

Regulated alternative pre-mRNA splicing is neither as widely appreciated as a fundamental aspect of controlled gene expression nor as thoroughly studied as transcriptional regulation. However, as exemplified by the phenomena cited in this review, alternative splicing is a fundamentally important mechanism used in the eukaryotic world to enhance the range, versatility and plasticity of the structural information contained within a gene, and to create additional strategies by which the net quantitative output of a given gene product can be controlled. Regulation of RNA splicing gives genes a modularity that adds flexibility, and, therefore, selective advantage, to eukaryotes. It is likely, though unproven, that this opportunity for refined regulation and diversification provides at least one basis for the existence of the tandem exon-intron-exon structure found in the vast majority of eukaryotic genes and many viral genes. Many examples of alternative splicing are known, but, for the majority, no obvious biological impact of the alternatively spliced proteins on known cellular functions can be appreciated. Examples by which selectively regulated splicing pathways alter both the physiology and pathology of a major cellular event, such as differentiation and mechanical function of the red cell membrane, are thus relatively rare. The protein 4.1 gene and mRNA products thus provide an instructive and unusual system in which to explore the broader issue of the role of these regulatory mechanisms in the overall scheme of gene regulation and adaptation. The fact that hereditary hemolytic anemias result from mutations that directly or indirectly disrupt the splicing system emphasized the relevance of these mechanisms to molecular medicine. The features of splicing that we have reviewed in this paper, and the specific impact that regulated splicing exerts on differentiating red cells have, we hope, convinced the reader that RNA splicing is an important, fascinating, and potentially fruitful area for future study of human disease processes.

Actins↗

PubMed1997

Leg lengthening by the Ilizarov technique for patients with sequelae of poliomyelitis.

Limb length discrepancy is common in patients with sequelae of poliomyelitis. However, treatment of this problem is difficult and complicated. From 1988 to 1993, 71 patients with sequelae of poliomyelitis were treated with leg lengthening by modifications of the Ilizarov technique. Their median age at surgery was 26.4 years (range, 11.6-38.1 yr). Patients were divided into four groups according to the method of treatment, with femoral lengthening in 18 patients, combined femoral and tibial lengthening in 6, tibial lengthening in 35, and tibial lengthening along and intramedullary locking nail in 12. At follow-up of 2 to 6.7 years, the combined femoral/tibial group had the greatest gain in length. Treatment time in the Ilizarov device was shortest in the tibial lengthening with locking nail group. The lengthening index, which was defined as days in the Ilizarov device required for each centimeter of lengthening (days/cm), was lowest in the tibial lengthening with locking nail group, followed by the combined femoral/tibial lengthening group. Complications such as soft tissue contracture, callus fracture and residual deformities were most common in the combined femoral/tibial lengthening group and the femoral lengthening group. Complications were least common in the tibial lengthening with locking nail group. The satisfaction rate was highest in the tibial lengthening with locking nail group. We found that in leg lengthening for patients with sequelae of poliomyelitis, callus maturation was slow, and patients tended to develop contractures despite physiotherapy, bracing or joint fixation. Concomitant and secondary surgery were frequently required to treat associated problems or residual deformities. Lengthening along an intramedullary locking nail can significantly shorten the treatment time with relatively few complications.

Adolescent↗

PubMed1997

Humeral lengthening using the Ilizarov technique.

Significant shortening of the humerus may cause cosmetic, psychologic and functional problems. From 1989 to 1993, we performed humeral lengthening using the Ilizarov technique on six patients. The indications were: 1) significant inequality (> 4-14 cm); 2) significant functional impairment; and 3) poor aesthetic appearance or related psychologic problems. THere were three females and three males, with a mean age of 17.7 years. The right humerus was affected in two patients, the left in four. Etiologies included sequelae of neonatal septic shoulder in three patients, sequelae of childhood trauma in one, malunion in one and congenital bone anomaly in one. Mean shortening of the humerus was 9.2 cm. Total average treatment time was 250 days. Mean lengthening was 8.7 cm. Complications included transient radial nerve palsy in one patient and delayed union in another. Bone grafting was performed on the patient who sustained delayed union. Fracture of the distraction site occurred after removing the Ilizarov device, and open reduction and internal fixation was performed. Functional and aesthetic status was improved in all six patients, over a minimum of 2 years follow-up. Lengthening of the humerus can be performed satisfactorily using the Ilizarov technique.

Adolescent↗

PubMed1997

Reconstruction for sequelae of septic hip in children.

Sequelae of septic hip in children may develop either due to inadequate management or neglect in the acute stage. We treated 13 patients (13 hips) with late sequelae of septic hip by reconstruction procedures, from 1985 to 1992. The mean age of the patients was 6.1 years. Their initial bony deformities were all beyond Hunka's classification type IIB. All of them had problems of hip instability and leg length discrepancy. With the intention to reestablish containment of the hip joint, open reduction, femoral osteotomy and pelvic osteotomy were performed. Four patients, all beyond Hunka type IV, had secondary surgery for hip resubluxation. Leg length discrepancies were corrected by valgus osteotomy and limb lengthening. At an average follow-up of 6.3 years, all remodeled hips were stable. Early reconstruction is recommended to stabilize the hip joint and restore the normal hip center for bone development. The leg length discrepancies were corrected by an Ilizarov limb lengthening procedure at a later stage.

Arthritis, Infectious↗

PubMed1997

Treatment of congenital pseudarthrosis of the tibia with the Ilizarov method.

Congenital pseudarthrosis of the tibia (CPT) is a difficult orthopedic problem. Many modalities of treatment have been used but none provide comprehensive treatment with highly satisfactory results. We reviewed the surgical management and results of eight consecutive patients with CPT treated with the Ilizarov technique for nonunion, angulation, leg length discrepancy and valgus ankle between 1988 and 1992. The median age at the time of Ilizarov treatment was 1.8 years (range, 0.4-20.1 yr). Primary union at the pseudarthrosis site was achieved in five of the eight patients. After a median follow-up period of 5.2 years (range, 3.0-6.2 yr), final union at the pseudarthrosis site was achieved in seven of the eight patients (union rate, 87.5%). However, nonunion persisted at the distraction site in one patient. In the six patients who achieved union and functional recovery, the median number of total surgeries was four; there were two residual deformities. Leg length discrepancy was corrected in these six patients to less than 1.7 cm. Six out of the eight patients were satisfied with the results. In general, the treatment course was lengthy with numerous complications, especially in young children. The Ilizarov technique, with its ring design, simultaneously addresses several problems associated with CPT, and may provide a comprehensive treatment for CPT with promising results. Combination treatment with other methods is necessary.

Adolescent↗

PubMed1997

Necrotizing enterocolitis in newborn: nine years' experience.

BACKGROUND: Necrotizing enterocolitis (NEC) is the most significant acquired gastrointestinal (GI) emergency in the neonatal intensive care unit. METHODS: We sought to gain a clinical perspective on NEC by reviewing the records of NEC patients over a 9-year period. The case histories of 22 infants with NEC treated from September 1, 1986 to September 1, 1995 were reviewed. RESULTS: Mean gestational age was 32 weeks and mean birth weight was 1774 grams. Eighteen percent were full term babies and 82% were premature. Average age at the onset of NEC was 11 days. The most common clinical manifestations were abdominal distension (100%), gastric retention (64%), unstable vital signs (59%) and Guaiac-positive vomitus or stool (36%). Sixteen cases (73%) were classified as stage III NEC, which has the highest mortality and/or morbidity. CONCLUSION: Early identification and management are critical to improve the outcome of NEC.

Birth Weight↗

PubMed1997

Surgical treatment of congenital convex pes valgus.

Congenital convex pes valgus is a rare, complex and heterogeneous anomaly of the foot, which is difficult to treat. From 1985 to 1994, we treated 14 patients (20 feet) with this deformity. There were six boys and eight girls. Six patients had bilateral involvement. Their ages at the time of surgery ranged from 4 to 32 months (mean, 13 mo). In eight patients (10 feet), the etiology was arthrogryposis multiplex congenita. The eitiology was unknown in six patients (10 feet). Associated problems included hip dislocation in seven patients, flexion or extension contractures of the knee in six patients, and clubfoot deformity in three patients. One patient had undergone previous surgery for release of a knee contracture. To achieve a plantigrade and balanced foot, all patients had one-stage surgical open reduction and circumferential release for the correction of deformities. At a minimum of 2 years following surgery, 11 patients (16 feet) had satisfactory results determined by a 10-point evaluation system based on both clinical and radiographic features. Satisfactory results and ambulatory prognosis were related to the etiology and severity of each patient's condition. Two patients (two feet) had scars with poor cosmetic appearance and two patients (three feet) had inadequate correction. We concluded that with adequate soft tissue release and complete talocalcaneonavicular joint reduction in one-stage surgery, proper postoperative maintenance, and physical therapy, satisfactory results in the treatment of congenital convex pes valgus can be achieved.

Arthrogryposis↗

PubMed1997

Effect of electrical stimulation on callus maturation during callus distraction in rabbits.

Callus distraction is currently the most widely used technique for limb lengthening. Prolonged treatment time is its main shortcoming. In this study, we tested the effectiveness of electrical stimulation during various stages of lengthening in order to decrease the treatment time. Seventy-five New Zealand white rabbits, about 2 kg in body weight, were divided into five groups. All groups received single level tibial lengthening of 1 cm by callotasis using a mini-lengthener. Group 1 rabbits did not receive electrical stimulation and could move freely in their cages. Group 2 rabbits (sham control), with electrodes on their left legs, were restrained on a wooden frame for 8 hours every day without electrical stimulation. Group 3 rabbits received capacitively coupled electrical stimulation, 60 kHz, 500 mV, on the left leg for 8 hours every day during the distraction period. Group 4 rabbits received electrical stimulation during the neutralization period. Group 5 rabbits received electrical stimulation during both the distraction and neutralization period. All rabbits were restrained during electrical stimulation. Weekly radiographs were taken to determine the time of appearance of at least three neocortices in the lengthening callus. At that time, the fixators were removed. The healing indexes (total time in fixator divided by length gained, days/cm) in the five groups of rabbits were compared. The range of motion of the ipsilateral knees and ankles and complications of treatment were recorded. The results showed that electrical stimulation applied during leg lengthening by callus distraction can significantly reduce the treatment time and the healing indexes, but the electrical stimulation may contribute to decreased motion in the ipsilateral knee and ankle joints.

Animals↗

PubMed1997

Sonographic study of the thymus in infants and children.

Because of variability in the size of the thymus, imaging in children is a challenge. Difficulties in differentiating an abnormal mediastinal mass from a normal thymus may lead to unnecessary investigations. We performed a prospective sonographic study of the normal thymus in 140 infants and children aged newborn to 8 years to determine the size of the normal thymic gland. Patients were classified into five groups by age: 1) less than 6 months, 2) 6-12 months, 3) 13-24 months, 4) 25-48 months, 5) more than 48 months. The thymus was scanned through the suprasternal, transsternal, and parasternal windows with a Sonos 1000 scanner and a 5.5-MHz sector probe. The thymus was visualized in at least one of the three windows and the width and thickness were measured in 133 of the 140 cases. The mean +/- standard deviation width and thickness were 3.67 +/- 0.64 cm and 1.30 +/- 0.25 cm in boys, and 3.45 +/- 0.59 cm and 1.20 +/- 0.26 cm in girls (p = 0.047 and p = 0.033 in width and thickness, respectively). Regression analysis demonstrated an increase, mainly in the width, with increasing age (width = 3.48 + (0.05 x age) cm, p = 0.009), indicating an increase of 0.05 cm per year. In conclusion, the thymus was clearly and easily visualized on sonograms in the majority of children we studied. This study established the normal size range of the thymus in children less than 8 years old.

Age Factors↗