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Biomedical subjects

S J Tredwell

Publications and source records attributed to S J Tredwell.

At least 19 recordsLinked to original sources
PubMed2005

Is osseous dysplasia a primary feature of neurofibromatosis 1 (NF1)?

Characteristic skeletal lesions are a cardinal feature of the autosomal dominant condition, neurofibromatosis 1 (NF1). The most frequently involved skeletal sites are the sphenoid wing, vertebrae, and tibia. Osseous lesions may range in severity in NF1 but are often progressive. They may lead to serious clinical consequences and be resistant to treatment. The skeletal lesions of NF1 are usually considered to be 'dysplasias', i.e. primary defects of bone, although there is no direct evidence supporting this interpretation. Moreover, it is difficult to understand why a generalized dysplasia of bone would produce focal lesions that show such a striking predisposition to only a few bones. We review the clinical and pathological features of NF1 skeletal lesions and propose that they result from an abnormal response of NF1 halpoinsufficient bone to abnormal mechanical forces rather than from a primary osseous dysplasia.

Biomechanical Phenomena↗
PubMed1999

Rotations of a helix as a model for correction of the scoliotic spine.

STUDY DESIGN: A prospective study using intraoperative stereophotogrammetry to analyze helical motion of the spine during the correction of scoliosis. OBJECTIVE: To determine whether derotation systems rotate the scoliotic helix. SUMMARY OF BACKGROUND DATA: Scoliosis is a complex three-dimensional deformity that is difficult to visualize on standard radiographs. The use of stereophotogrammetry has allowed study of the deformity in three dimensions during surgical correction. METHODS: Thirty-five patients with right thoracic adolescent idiopathic scoliosis were studied using a stereophotogrammetry technique during surgical correction. Changes in vertebral unique rotations and spinal plane of maximum deformity were measured during three sequential stages of the surgery. RESULTS: The mean preoperative and postoperative Cobb angles were 58 degrees and 19 degrees, respectively. Most rotation occurred at the top and bottom vertebrae in the curve, averaging 10 degrees each but in opposite directions. The apical vertebra rotated the least in the structural curve, with an average rotation of 5 degrees. Much of the rotation occurred during the derotation maneuver with additional rotation occurring during the final distraction. The plane of maximum deformity changed from a mean of 50 degrees before instrumentation to 19 degrees at the end of the procedure. CONCLUSIONS: Multiple rotations of the scoliotic curve occur, and it can be shown when maximum rotations occur during surgery. Posterior derotational systems unwind or rotate the scoliotic helix and reposition the resultant sine wave toward the sagittal plane as described by the change in the plane of maximum deformity.

Adolescent↗
PubMed1998

Effects of three-dimensional assessment on surgical correction and on hook strategies in multi-hook instrumentation for adolescent idiopathic scoliosis.

STUDY DESIGN: A prospective study using intraoperative stereophotogrammetry to analyze change during the correction of scoliosis. OBJECTIVE: To examine the relation between the number of hooks used during segmental instrumentation and the amount of correction achieved. SUMMARY OF BACKGROUND DATA: An intraoperative stereophotogrammetric technique was developed at our center. Vertebral translations and rotations can be measured at several stages during scoliosis surgery. METHODS: Thirty-two patients with right thoracic adolescent idiopathic scoliosis were studied using our stereophotogrammetry technique during surgical correction. Correlations were determined between apical vertebral movements and the hook ratio (number of vertebrae/number of hooks used). RESULTS: Mean curve Cobb angle correction was 66%. Correction occurred in all three planes but primarily along the x and y axes. Scoliotic deformity was corrected by translation of the vertebra along the y axis and rotation about the x; physiologic kyphosis was restored by translation along the x axis and rotation about the y. The plane of maximum deformity as compared with the sagittal plane of the patient corrected from 57 degrees to 25 degrees as an indication of detorsion of the scoliotic deformity. CONCLUSIONS: Increasing the number of hooks per vertebral segment significantly enhances the correction of the coronal scoliotic deformity and enhances the z axis derotation, but does not significantly change the reestablishment of the kyphosis, nor does it result in significant elongation of the spine.

Adolescent↗
PubMed1995

The role of autologous blood transfusion in adolescents undergoing spinal surgery.

STUDY DESIGN: A prospective study of 147 consecutive patients undergoing spinal surgery who were analyzed for response to an effect of an offered autologous blood program. OBJECTIVES: Analysis of the impact of the autologous program within a comprehensive blood conservation philosophy toward the reduction in the use of homologous blood. METHODS: Each patient was prescreened by the autologous program for inclusions and ability. Physical parameters were recorded as were predonation and postdonation hemoglobin levels. The volume of each donation and the number of autologous and homologous units transfused and total operating blood loss were recorded as were complications during donation and transfusion. RESULTS: One hundred sixteen of the original one hundred forty-seven patients participated in the program and donated between 150 and 1900 ml of blood during the preoperative period. Of these, 35 patients weighed 45 kg or less. Diagnoses included 97 cases of idiopathic scoliosis and the remainder had spinal deformities of other causes. Of the entire group, 13 patients (11%) received homologous blood transfusion, 7 of these patients had diagnoses other than idiopathic scoliosis. CONCLUSIONS: In this study of 116 patients, 89% of the spinal surgeries were successfully completed using only autologous blood. This compared favorably with a historical control group in which 60% of the patients required homologous blood transfusion. It is concluded that the use of autologous blood donation combined with other blood conservation techniques has significantly lessened the need for homologous transfusion.

Adolescent↗
PubMed1995

Atlantoaxial subluxation in children with seronegative enthesopathy and arthropathy syndrome: 2 case reports and a review of the literature.

We describe 2 HLA-B27 positive children with seronegative enthesopathy and arthropathy (SEA) syndrome who developed spontaneous (nontraumatic) atlantoaxial subluxation early in their disease course. Neither child had evidence of spinal cord compression but both had progressive atlantoaxial subluxation in spite of conservative treatment. Both underwent elective posterior cervical (C1-C2) fusion.

Adolescent↗
PubMed1992

Neonatal screening for hip joint instability. Its clinical and economic relevance.

Effort to determine the efficacy of neonatal hip examination began in 1967. During the subsequent 23 years, there have been three analyses of the study's data: (1) a retrospective review reported in 1981, (2) a prospective examination in 1989, and (3) an economic evaluation in 1990. The retrospective review concluded that a neonatal hip screening program effectively screens for acetabular dysplasia, and early treatment seems to alter the outcome of congenital dislocation of the hip. The prospective examination, involving 62 newborns diagnosed as having dislocated or dislocatable hips, established that such cases can be effectively treated from birth with flexion/abduction splints monitored by routine clinical and follow-up examinations. An economic evaluation of the data demonstrated an economic benefit of more than $15,000 Cdn per 1000 infants screened. This study, through these three analyses, presents a compelling argument in favor of a routine, standardized neonatal hip examination.

False Negative Reactions↗
PubMed1990

The use of fibrin sealant to reduce blood loss during Cotrel-Dubousset instrumentation for idiopathic scoliosis.

The increased complexity of Cotrel-Dubousset instrumentation has, as an unexpected side effect, a potential increase in blood loss. A prospective randomized study was undertaken to test the hypothesis that application of a fibrin sealant to exposed cancellous bone can significantly reduce blood loss during Cotrel-Dubousset instrumentation for idiopathic scoliosis. A significant difference was demonstrated in total body loss, loss per level fused, and loss per kilogram of body weight when comparing the sealant group with random controls. A significant difference was demonstrated in loss per level fused when comparing the sealant control with a historical control group. Thirty-three patients were randomly assigned to the fibrin sealant or nonsealant groups; another 10 patients operated on before planning the study were included as historical controls. The sealant was used to control bleeding at the bone graft donor site and in the spine after decortication. All patients underwent Cotrel-Dubousset instrumentation for idiopathic scoliosis. There were no significant differences between groups with respect to degree of curvature, number of levels fused, age or weight of patient, or operating time. Total blood loss in the sealant group averaged 672 ml compared with 894 ml in the sealant control group. No patient in the sealant group required homologous blood. Given the increasing awareness of the complications of blood transfusion, the authors conclude that fibrin sealant is a useful adjunct to spinal surgical technique.

Adolescent↗
PubMed1988

The use of the ISIS optical scanner in the management of the braced adolescent idiopathic scoliosis patient.

Thirty-four adolescent female patients with right thoracic idiopathic scoliosis were followed for a mean of 8.6 months to document progression of scoliosis curvature during bracewear. Prediction of change by deviation of the lateral asymmetry index on ISIS examination were compared with measured change on standard upright roentgenograms. A one-to-one correlation was found in 50% of the patients; five patients were predicted to have stayed the same or decreased by ISIS and showed increase on x-ray measurement. Eight patients were predicted to have stayed the same or decreased by x-ray measurement and showed increase by ISIS. Although a weak positive correlation exists between change by x-ray examination and change by ISIS examination in a braced population, the clinical usefulness of the ISIS method in following a braced population has not been proven.

Adolescent↗
PubMed1984

Orthopaedic aspects of the trismus pseudocamptodactyly syndrome.

The trismus pseudocamptodactyly syndrome is a relatively rare condition with autosomal dominant inheritance, characterized by decreased ability to open the mouth (trismus), interphalangeal flexion deformity with wrist extension (pseudocamptodactyly), various foot deformities, and slightly less than normal stature. Five affected individuals from one family are reviewed and the orthopaedic aspects are described. The presence of trismus is emphasized for the orthopaedic surgeon, as it may lead to anaesthetic complications during the treatment of the musculoskeletal problems.

Abnormalities, Multiple↗
PubMed1984

Pattern of forearm fractures in children.

Retrospective analysis of 500 consecutive fractures of the forearm in normal children was conducted. The fracture pattern secondary to fall on the out-stretched arm in the pediatric age group is for the fracture line to progress from proximal to distal with advancing skeletal age. Fractures falling outside described norms for the age represent a different population. In the older child they are an increased indication for open reduction, and in the younger child indicate an increased possibility of child abuse. Changes in the radial shaft occurring with maturity place differing areas at risk and are offered as the major reason for the fracture pattern. Epiphyseal fractures of the forearm were primarily fractures of early adolescence rather than childhood.

Child↗
PubMed1983

The weightbearing shoulder.

To determine the effect of the swing-through crutch-walking gait on shoulder degeneration, 20 shoulders were examined in ten patients who had used the swing-through gait for a mean of 8.7 years. No degenerative changes were found in the 20 examined shoulders either clinically or radiographically. A special X-ray view was determined to assess potential degenerative changes. The patients showed a mean increase in the forearm bone density as a result of their crutch-walking gait.

Adult↗
PubMed1981

Efficacy of neonatal hip examination.

An examination of the ongoing neonatal hip screening program at the Vancouver General and Grace Hospitals in Vancouver, British Columbia, over a 9 1/2 year period revealed that of the 32,480 newborns examined, 321 (9.8 per 1,000 live births) had unstable hips. Treated immediately with abduction splintage, five of these children came to percutaneous adductor tenotomy and hip spica casts. There was one false-negative screening, and there were five children with unidentified acetabular dysplasia who presented within the first year of life. No child came to open reduction of the hip or innominate or femoral osteotomy. A standardized neonatal hip screening program would seem to significantly alter the natural history of the classic congenital dislocation of the hip but also seems unable to effectively screen out acetabular dysplasia.

British Columbia↗
PubMed1980

An ultrastructural study of multifidus muscle in progressive idiopathic scoliosis. Changes resulting from a sarcolemmal defect at the myotendinous junction.

Biopsies of multifidus muscles were procured from patients with idiopathic scoliosis prior to Harrington rod instrumentation. Specimens from both convex and concave sides at the apex of the curve were examined by light and electron microscopy and compared with normal muscle samples. Abnormalities were detected on the concave aspect of the curve and the most dramatic morphological changes were noted at the myotendinous junction. Here a structural defect in the form of discontinuities in the sarcolemmal membranes of some muscle fibres was accompanied by large numbers of intimately-adhering connective tissue cells. Structural disorganization of the associated tendon occurred in conjunction with increased vascularization and with fatty cell and leukocyte infiltration. Further from the myotendon junction, structural lesions appeared more chronic and non-specific subsequent to the incipient sarcolemmal break in the affected muscle fibres. Hypertrophy, atrophy, centralization of nuclei, and disruption of sarcotubular and myofibrillar elements were noted in some muscle cells. While the aetiology of this disorder is unknown, a supposition is made that the primary change is an inherent weakness and subsequent break in the sarcolemma at the myotendon junction. This site is an important clue to the pathogenesis of this disease since it reflects morphological change in rapidly growing tissue occurring at the time of the rapid adolescent growth spurt leading to progression of the scoliotic curve.

Adolescent↗
PubMed1976

Skeletal growth and development of the achondroplastic dwarf.

Certain patterns in growth and development can be seen in the typical achondroplastic dwarf. Height is approximatley 5 standard deviations below average size for age through the age of 14. Sitting height is within normal limits at all ages. On the average the femur is 8 standard deviations and the tibia 7 standard deviations below normal size. Compared to normal, both femur and tibia exhibit approximately a 50 per cent inhibition in growth. A slight decrease in the deviance from the norm is observed for all parameters during growth until the time of the adolescent growth spurt when an increased deviance is seen. Related to normal children of the same sex and age, females are more severely affected than male achondroplastic dwarfs. The skeletal development of the hand is irregular, often having extra metacarpal epiphyses and a wide variance in skeletal maturation assessment between the carpals and the rest of the hand. The skeletal age is generally below chronological age until the adolescent growth spurt when a rapid maturation pattern occurs. Standard skeletal age assessment techniques cannot be applied to the achondroplastic individual.

Achondroplasia↗
PubMed1975

Avascular necrosis of the proximal end of the dens. A complication of halo-pelvic distraction.

Roentgenographic evidence of avascular necrosis of the upper part of the dens was observed in thirteen of ninety-four patients treated for tuberculous kyphosis or non-tuberculous scoliosis using halo-pelvic distraction. Four patients had some residual loss of motion. A significant relationship was demonstrated between avascular necrosis and the amount of distraction visible on roentgenograms.

Adolescent↗