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Biomedical subjects

R T Loder

Publications and source records attributed to R T Loder.

At least 19 recordsLinked to original sources
PubMed2003

Congenital longitudinal deficiency of the tibia.

We performed a clinical and radiographic review of 15 patients (19 limbs) with longitudinal deficiency of the tibia treated between 1981 and 2001. Ten limbs with Kalamchi type I deficiencies were managed by through-knee amputation. Five type II deficiencies were treated by foot ablation and tibiofibular synostosis, either at the same time or staged, but prosthetic problems may arise from varus alignment and prominence of the proximal fibula. Patients with type III deficiencies (four cases) were treated by foot ablation. Prosthetic problems relating to proximal or distal tibiofibular instability may necessitate additional surgical intervention.

Abnormalities, Multiple↗
PubMed2001

The sagittal profile of the cervical and lumbosacral spine in Scheuermann thoracic kyphosis.

The sagittal profiles of the cervical and lumbar spine have not been studied in Scheuermann kyphosis. The purpose of this study was to investigate these profiles. Standing lateral radiographs of the spine in 34 children with Scheuermann kyphosis were reviewed. Cervical lordosis, lumbar lordosis, thoracic kyphosis, sagittal vertebral axis, and sacral inclination were measured. The relations between these variables were explored using the Pearson correlation. The average patient age was 15.5 +/- 1.8 years, thoracic kyphosis was 65 degrees +/- 12 degrees, lumbar lordosis 71 degrees +/- 13 degrees, and cervical lordosis 4 degrees +/- 15 degrees (Cobb angle), and 9 degrees +/- 14 degrees (posterior vertebral body angle [PVBA]). No correlations were noted between cervical lordosis and thoracic kyphosis. Correlations were noted between cervical lordosis and lumbar lordosis (r2 = 0.17, Cobb angle; r2 = 0.16, PVBA) and between cervical lordosis and the residual sagittal difference (thoracic kyphosis minus lumbar lordosis; r2 = 0.32, p = 0.001 [Cobb angle], and r2 = 0.19, p = 0.01 [PVBA]). In Scheuermann kyphosis, the flexible cervical and lumbar spine is linked by the intermediate rigid thoracic segment. As the residual sagittal difference becomes more kyphotic, lordosis of the cervical spine increases as the patient strives to maintain a forward visual gaze.

Adolescent↗
PubMed2001

Profiles of the cervical, thoracic, and lumbosacral spine in children and adolescents with lumbosacral spondylolisthesis.

The sagittal and frontal profiles of the entire spine are poorly studied in lumbosacral spondylolisthesis. It was the purpose of this study to further investigate these profiles. Standing posterior-anterior and lateral radiographs in 24 children with lumbosacral spondylolisthesis were reviewed (18 isthmic, 6 congenital). Cervical lordosis, lumbar lordosis, thoracic kyphosis, sagittal vertebral axis, sacral inclination, slip magnitude, slip angle, and sagittal rotation were measured. Cobb magnitude, Risser sign, curve location, and direction were noted for those with scoliosis. Relationships between sagittal variables were explored (Pearson correlation). The average age of patients was 14.7 +/- 2.5 years, slip magnitude was 38 +/- 38%, slip angle was 5 +/- 31 degrees, sagittal rotation was -6 +/- 31 degrees, thoracic kyphosis was 29 +/- 16 degrees, cervical lordosis was -1 +/- 12 degrees, and lumbar lordosis was 62 +/- 22 degrees. Correlations were noted between thoracic kyphosis and sacral inclination, percent slip, slip angle, and sagittal rotation. Sacral inclination decreased as the slip increased. Scoliosis was present in 10 children, with an average curve of 19 +/- 6 degrees. Thoracic kyphosis was less in those with scoliosis (21 +/- 25 degrees versus 33 +/- 25 degrees, p = 0.033). In children with lumbosacral spondylolisthesis, the sacrum becomes more vertical as the slip worsens. As the sacrum becomes more vertical, the thoracic spine becomes more lordotic, which is likely an adaptive mechanism used by the body to maintain forward visual gaze.

Adolescent↗
PubMed2000

Horner's syndrome after posterior spinal fusion in a child: a case report.

STUDY DESIGN: A case report of a complication after posterior spinal fusion. OBJECTIVES: To present the clinical findings of a Horner's syndrome after posterior spinal fusion. SUMMARY OF BACKGROUND DATA: A 14-year-old girl underwent posterior spinal fusion for idiopathic scoliosis. METHODS: Clinical examination and pharmacologic pupillary testing were used to diagnose Horner's syndrome. RESULTS: After surgery, the patient developed a left-sided Horner's syndrome. The Horner's syndrome had resolved 6 months after surgery except for slight ptosis. CONCLUSIONS: This is the first reported case of Horner's syndrome occurring after posterior spinal fusion without the use of epidural analgesia.

Adolescent↗
PubMed2000

Automated parallel DNA sequencing on multiple channel microchips.

We report automated DNA sequencing in 16-channel microchips. A microchip prefilled with sieving matrix is aligned on a heating plate affixed to a movable platform. Samples are loaded into sample reservoirs by using an eight-tip pipetting device, and the chip is docked with an array of electrodes in the focal plane of a four-color scanning detection system. Under computer control, high voltage is applied to the appropriate reservoirs in a programmed sequence that injects and separates the DNA samples. An integrated four-color confocal fluorescent detector automatically scans all 16 channels. The system routinely yields more than 450 bases in 15 min in all 16 channels. In the best case using an automated base-calling program, 543 bases have been called at an accuracy of >99%. Separations, including automated chip loading and sample injection, normally are completed in less than 18 min. The advantages of DNA sequencing on capillary electrophoresis chips include uniform signal intensity and tolerance of high DNA template concentration. To understand the fundamentals of these unique features we developed a theoretical treatment of cross-channel chip injection that we call the differential concentration effect. We present experimental evidence consistent with the predictions of the theory.

Automation↗
PubMed1998

Slipped capital femoral epiphysis.

Slipped capital femoral epiphysis occurs during the adolescent growth spurt and is most frequent in obese children. Up to 40 percent of cases are bilateral. Recent classification methods emphasize epiphyseal stability rather than symptom duration. Most cases of slipped capital femoral epiphyses are stable and have a good prognosis if diagnosed early. Unstable slipped capital femoral epiphysis has a much poorer prognosis because of the high risk of avascular necrosis. Early radiographic clues are the metaphyseal blanch sign and Klein's line. Once diagnosed, treatment should begin immediately. The most widely accepted treatment for a stable slipped capital femoral epiphysis is in situ fixation with a single central screw. The treatment for an unstable slipped capital femoral epiphysis is much more controversial. Corrective osteotomy is usually reserved for treatment of severe deformities after the patient has stopped growing.

Diagnosis, Differential↗
PubMed1998

Head-wag autotomography of the upper cervical spine in infantile torticollis.

BACKGROUND: Infants with torticollis require evaluation of the entire cervical spine for vertebral anomalies as part of the work-up, but open-mouth views to assess occiput to C2 are difficult to obtain. OBJECTIVE: To evaluate a "head wag" autotomographic technique for the frontal projection of this region. MATERIALS AND METHODS: Twenty infants under one year of age were evaluated using this technique. RESULTS: Sixteen of 20 could be adequately evaluated using this simple, low-radiation-dose procedure. CONCLUSION: For infants with torticollis in whom vertebral anomalies need to be excluded, the "head wag" technique is useful.

Cervical Vertebrae↗
PubMed1998

Pubic symphysis repair strength in simulated bladder exstrophy using a sheep model.

OBJECTIVES: To investigate the mechanical strength of various pubic symphysis suture material in a simulated animal model of neonatal bladder exstrophy. METHODS: Neonatal lamb pelves, which are the approximate size of neonatal human pelves, were used. Twenty-four neonatal lamb pelves were divided into four equal groups. A midline symphysotomy was made through the cartilaginous pubic symphysis in three groups and repaired using two figure-of-eight sutures (size 0) placed through the cartilaginous pubis using polypropylene, braided polyester, or polyglactin. The fourth group served as the control. The pelves were then tested to ultimate load in pure tension at a strain rate of 0.25 mm/s until failure. RESULTS: There was a highly significant difference between the intact specimens and the repaired specimens (P = 0.0008). For the repaired specimens, there was a significant difference in the ultimate load normalized by pubic height between those repaired with polypropylene and polyglactin (P = 0.025), but not for those repaired with polypropylene and braided polyester (P = 0.11) or braided polyester and polyglactin (P = 0.11). CONCLUSIONS: Braided resorbable sutures are recommended for pubic symphysis repair, because they have a lower tendency to cut out of the cartilage.

Animals↗
PubMed1996

The role of melatonin in the pathogenesis of adolescent idiopathic scoliosis.

STUDY DESIGN: A matched, case-control study comparing melatonin production in female patients with and without adolescent idiopathic scoliosis. OBJECTIVES: To determine whether melatonin production is decreased in adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: A central etiology for idiopathic scoliosis has never been established. Previous authors have produced experimental scoliosis in chickens after pinealectomy, preventable by administration of melatonin. They suggested that a defect in melatonin synthesis might be involved in the pathogenesis of human idiopathic scoliosis. METHODS: Nine female adolescents with no medical problems, normal neurologic examinations, radiographic idiopathic scoliosis of 15-40 degrees, and Risser Stage I-III were in the patient group. Eighteen healthy adolescent girls with no medical problems, a negative school screening, and no family history of scoliosis were control subjects. Patients and control subjects were matched for age, weight, Tanner stage, sleep duration, and light exposure by multiple linear regression. Nighttime and daytime urine samples were analyzed for melatonin by high-performance liquid chromatography. RESULTS: Although nighttime melatonin levels were significantly higher than daytime levels in all volunteers (P < 0.00002), there were no significant differences in nighttime (P > 0.63) or daytime (P > 0.78) melatonin levels between patients and control subjects, even after matching by multiple linear regression analysis. A statistical analysis demonstrated that if a melatonin deficiency of 25% or more did exist in patients with scoliosis compared with control subjects, the likelihood that it would have been detected in this study was more than 98%. CONCLUSION: Although melatonin deficiency may cause scoliosis in the chicken, this study suggests that it is not a mechanism in the pathogenesis of adolescent idiopathic scoliosis in humans.

Adolescent↗
PubMed1996

Orthopedics.

Explore the source record for details and available documents.

Bone Diseases↗
PubMed1996

Slipped capital femoral epiphysis. The prevalence of late contralateral slip.

We evaluated the prevalence of slipped capital femoral epiphysis in the contralateral hip of 169 children who had been managed with pinning in situ and thirty who had been managed with immobilization in a spica cast. Only children who had initially been seen with a unilateral slip and had been followed for a minimum of two years or until skeletal maturity were included in the study. The average duration of follow-up was 3.6 years (range, 0.5 to 9.5 years) for the group that had been managed with a cast and 2.8 years (range, 1.0 to 8.3 years) for the group that had been managed operatively. In sixty-one (36 per cent) of the 169 patients who had had operative treatment and two (7 per cent) of the thirty who had been managed with a spica cast, a slip subsequently developed in the contralateral hip; this difference was significant (p = 0.001). On the basis of these findings, we recommend that closer attention be paid to the potential development of a slip in the contralateral hip after pinning.

Adolescent↗
PubMed1996

A worldwide study on the seasonal variation of slipped capital femoral epiphysis.

The records of 1630 children (671 girls, 959 boys) with 1993 slipped capital femoral epiphyses were reviewed. These children were from all 6 continents and 33 orthopaedic centers. The month of the slip onset was defined as the month when the patient presented to the physician minus the duration of symptoms as reported by the patient. There was a significant variation in the month of onset for the children from North America and Europe, but not Africa, Asia, Australia/New Zealand, or South America. The peak month of onset was 6.8 +/- 2.6 in North America (late June) and 7.9 +/- 2.4 in Europe (late July). This phenomenon of slips occurring significantly more often in the summer months was only present when the children lived north of the 40 degrees N latitude.

Child↗
PubMed1996

The demographics of slipped capital femoral epiphysis. An international multicenter study.

One thousand six hundred thirty children with 1993 slipped capital femoral epiphyses were reviewed; 41.2% were girls and 58.8% were boys. There were 47.5% white, 24.8% black, 16.9% Amerindian, 7.4% Indonesian-Malay, 2.1% Native Australian/Pacific Islands, and 1.3% Indo-Mediterranean children. The diseased hip was unilateral in 77.7% and bilateral in 22.3% of the children, and chronic in 85.5% and acute in 14.5% of the children. Of the unilateral slips, 40.3% involved the right hip and 59.7% the left hip. The child's weight was greater than or equal to the ninetieth percentile in 63.2% of the children. The average age for the girls and boys was 12 and 13.5 years. The age at diagnosis decreased with increasing obesity. The youngest children were the Native Australian/Pacific Island children (11.8 years) and the oldest were the white and Indo-Mediterranean children (13 years). The Indonesian-Malay and Indo-Mediterranean children were the lightest in weight, and the black children the heaviest. The Indo-Mediterranean children had the highest proportion of boys (90.5%), and the Native Australian/Pacific Island children the lowest (50%). The highest percentage of bilaterality was in the Native Australian/Pacific Island children (38.2%), and the lowest in the Amerindian children (16.5%). The relative racial frequency of slipped capital femoral epiphysis compared with the white population was 4.5 for the Polynesian, 2.2 for the black, 1.05 for the Amerindian, 0.5 for the Indonesian-Malay, and 0.1 for the Indo-Mediterranean children. In children with unilateral involvement, the age at presentation was younger for those children in whom bilateral disease later developed (12 versus 12.9 years old). In 82% of the children with sequential bilateral slips, the second slip was diagnosed within 18 months of the first slip.

Adolescent↗
PubMed1996

Treatment of the unstable (acute) slipped capital femoral epiphysis.

Slipped capital femoral epiphysis, the most common hip disorder in adolescence, traditionally has been classified according to symptom duration. An acute slip is 1 in which there are symptoms for < 3 weeks; for a chronic slip, there are symptoms for > 3 weeks. An acute-on-chronic slip is characterized by a combination of both with a recent exacerbation of symptoms. This classification system is misleading because it does not consider stability. A stable slipped capital femoral epiphysis has a good prognosis, but an unstable slip has a guarded prognosis. The priorities in treating an unstable (acute) slip are (1) to avoid avascular necrosis, (2) to avoid chondrolysis, (3) to prevent further slip, and (4) to correct deformity. The last priority, correcting the deformity, is associated with a high incidence of complications including avascular necrosis and chondrolysis, so manipulative reduction under anesthesia or an acute corrective osteotomy is not recommended. To address these priorities in treatment, the authors recommend preoperative bed rest to decrease the synovitis and intraarticular effusion. Operative stabilization is done in an elective fashion once the synovitis has subsided. The technique includes careful patient positioning on the fracture table, which may cause an incidental reduction, but no attempt is made to do a manipulative reduction. The technique is dependent on radiographic control. The femoral head and neck must be well visualized on the anteroposterior and lateral intensifier images before the operation is started. The slipped capital femoral epiphysis is stabilized with a single central screw, and nonweightbearing ambulation with crutches is recommended until a satisfactory painless range of motion has returned.

Acute Disease↗
PubMed1995

Slipped capital femoral epiphysis in children.

Two new classification schemes have been described for slipped capital femoral epiphysis (SCFE); both involve the question of stability and are probably more prognostic than the traditional acute or chronic classification. The prevalence of bilaterality is approximately 33%, and two recent series regarding bilateral SCFE recommend frequent follow-up after a child presents with a unilateral SCFE, but they do not recommend prophylactic pinning of the normal hip. In the case of a child with an underlying endocrine disorder who presents with a unilateral SCFE, however, strong consideration should be given to prophylactic pinning of the opposite hip. The most commonly accepted method of fixation at this time is in situ pin fixation with a single central screw. The screw head should be no more than 1.5 cm from the cortex of the femur to prevent windshield-wiper loosening. Chondrolysis, a complication of both untreated and treated SCFE, has a more favorable prognosis than idiopathic chondrolysis.

Bone Screws↗
PubMed1995

Divergent single-column fractures of the distal part of the humerus.

We report an unusual intra-articular fracture of the distal part of the humerus that was seen in five patients, including one who had the fracture bilaterally. The fractures were characterized by three features. First, the fractures were initiated in the trochlear groove as a result of a direct impact on the olecranon, which divided the trochlea and then split the two columns of the humerus divergently. Second, the fractures occurred exclusively in adolescents and young adults (average age, fifteen years old; range, thirteen to twenty years old). Third, all of the fractures were seen in patients who had a large fossa or septal aperture between the coronoid and olecranon fossae. Four of the fractures involved the right side and two, the left. There were three fractures of the lateral column and three of the medial column. Because the periosteum, the capsule, and the ligaments remained intact despite intra-articular displacement of the distal part of the humerus, these fractures were also characterized by inherent proximal stability. The fractures were treated with closed reduction and percutaneous internal fixation to reduce the displacement between the two halves of the trochlea. All of the fractures united. Four patients (five elbows) regained full motion by eight months; one patient was lost to follow-up. Current classification systems that describe single-column fractures of the distal part of the humerus should be modified to include this unusual fracture pattern.

Adolescent↗
PubMed1995

Physeal slope in Perthes disease.

In 40 children with unilateral Perthes' disease, we measured the physeal slope, the angle between the physeal plane and the axis of the femoral shaft, from radiographs taken early in the disease. Thirty-seven of the 40 hips were classified as Catterall grades III and IV. Heat-at-risk signs were present in 23. We found no statistically significant difference in the physeal slope between the involved and normal hips (p = 0.20), those with or without head-at-risk signs (p = 0.96), those with or without lateral epiphyseal subluxation (p = 0.82), and different Catterall (p = 0.56) or lateral pillar (p = 0.67) gradings.

Analysis of Variance↗