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Biomedical subjects

M F Schafer

Publications and source records attributed to M F Schafer.

At least 19 recordsLinked to original sources
PubMed1993

The use of dermatomal evoked responses during surgical procedures that use intrapedicular fixation of the lumbosacral spine.

Monitoring of electrophysiologic function during intrapedicular fixation of the lumbosacral spine can be useful because this fixation technique has been associated with a significant number of postoperative radicular complications. Somatosensory evoked potentials (SEPs) traditionally have been used to monitor neurologic function during spinal instrumentation procedures. A case is presented of an intrapedicular fixation procedure that was monitored with SEPs and that resulted in false-negative SEP findings. This result suggests that SEPs may not be a sensitive enough monitoring tool for detecting compromise of single root function, and as a result, other monitoring techniques should be used. Dermatomal somatosensory evoked potentials (DSEPs) have been reported to be useful in this regard. To test their usefulness, 81 lumbosacral intrapedicular fixation procedures were monitored with DSEPs. Repeatable responses were obtained from all but one of the patients. The responses were sensitive to the compromise of root function. Predictions of postoperative outcome were dependent only on the responses at closing and not on changes that occurred during surgery.

Adult↗
PubMed1993

MR evaluation of the anterior cruciate ligament: value of supplementing sagittal images with coronal and axial images.

OBJECTIVE: Most studies evaluating the anterior cruciate ligament have focused on sagittal MR images for the diagnosis of injury. Limitations of sagittal images have been reported, however, including nonvisualization and incomplete visualization of the ligament. This study was undertaken to assess the value of adding coronal and axial MR images to sagittal images in the evaluation of the anterior cruciate ligament. MATERIALS AND METHODS: We reviewed oblique sagittal T1-weighted, coronal T2-weighted, and axial T2-weighted images to determine the status of the anterior cruciate ligament in 325 patients. All patients had arthroscopy. Sagittal images were initially interpreted alone and then in combination with coronal and axial images. RESULTS: Sagittal T1-weighted images alone had a 94% sensitivity and an 84% specificity for determining the status of the anterior cruciate ligament. A multiplanar evaluation of the anterior cruciate ligament resulted in a change in MR interpretation in 21 patients (6%), which led to an improved sensitivity of 98% and a specificity of 93%. Diagnostic confidence was improved in an additional 14 patients (4%). CONCLUSION: Our results show that the efficacy of MR imaging for the detection of anterior cruciate ligament tears is greater when axial and coronal images are used in combination with sagittal images than when sagittal images are used alone.

Adult↗
PubMed1992

Anterior cruciate ligament injury: MR imaging diagnosis and patterns of injury.

The anterior cruciate ligament (ACL) is an important stabilizer of knee motion. Injury of the ACL can lead to substantial disability; an accurate diagnosis of ACL injury is vital in both short-term and long-term patient care. Magnetic resonance (MR) imaging has emerged as the study of choice to evaluate the status of the ACL and other associated structures in the knee. Sagittal MR images have been commonly used in the evaluation of the ACL. However, the authors believe that coronal and axial imaging planes can add useful information about ACL injury and, thus, lead to improved accuracy and confidence regarding diagnosis. Multiplanar imaging can readily demonstrate meniscal, ligamentous, and bone marrow injuries that commonly occur with the most frequent mechanisms of ACL injury. These mechanisms, in order of frequency, include internal rotation and valgus stress, hyperextension, and varus stress with external rotation. An understanding of these mechanisms is helpful in the MR diagnosis of ACL injury.

Anterior Cruciate Ligament Injuries↗
PubMed1991

The natural history of congenital kyphosis in myelomeningocele. A review of 51 children.

The progression of congenital lumbar kyphosis in myelomeningocele is a well-known problem, but rates of progression are not well documented in the literature. Fifty-one children with congenital kyphosis and myelomeningocele were followed for an average of 4.8 years. Minimum follow-up was 1 year. Group I (35 patients) had initial radiographs at 1 year of age or less. Group II (16 patients) had radiographs taken after the age of 1 year. Curves less than or equal to 90 degrees in Group I progressed 7.7 degrees/yr; those greater than 90 degrees progressed 12.1 degrees/yr. Curves less than or equal to 90 degrees and greater than 90 degrees progressed at similar rates, regardless of initial curve magnitude: 6.4 degrees/yr and 6.7 degrees/yr, respectively. No correlation existed among the rate of curve progression, the frequency of shunt revisions, or the presence of vertebral anomalies, aside from the dysraphism.

Child↗
PubMed1989

Upper extremity arterial injury in athletes.

Between 1983 and 1986, 23 athletes were evaluated for arm and hand complaints. Eleven players had symptoms of thoracic outlet compression. Severe arm fatigue (eight patients) and finger ischemia (three patients) were the presenting symptoms. In the remaining 12 athletes, symptoms of hand ischemia were predominant. Noninvasive testing with Doppler ultrasonography and duplex scanning (positional testing and finger systolic pressure recording) and cold immersion were used to aid in diagnosis. In the 11 athletes with thoracic outlet compression, arteriography confirmed the finding with compression of the subclavian artery in five, the axillary artery in one, both subclavian and axillary arteries in two, posterior humeral circumflex artery in one, and subclavian aneurysm in two. Compression of the suprascapular artery was identified in four, the subscapular artery in two, and the posterior humeral circumflex artery in one. Thrombosis of a first baseman's ulnar artery and occlusion of the palmar arch in a frisbee player were documented by arteriography. Decompression of the thoracic outlet consisted of anterior scalenectomy in five, pectoralis minor muscle division in one, and resection of both muscles in two. Removal of cervical rib with interposed vein graft was performed in the two players with arterial aneurysm. Hand ischemia in the remaining athletes was treated conservatively with Dextran-heparin infusion for acute ischemia. Repeat noninvasive study of all players demonstrated absence of compression in their playing position, and all have resumed their playing careers. Hand ischemia in athletes can be evaluated noninvasively and treated conservatively. Resection of hypertrophied muscles to decompress the thoracic outlet together with release of branch artery compression in selected athletes promotes perfusion to arm and shoulder muscles and helps to avoid the catastrophic complication of repetitive trauma leading to sudden arterial thrombosis.

Adolescent↗
PubMed1986

Surgical management of adult scoliosis.

In a retrospective analysis of 62 adult scoliotic patients with an average age of 34 years, 39 patients were treated by single-stage posterior fusions, 19 by Harrington instrumentation, and 20 by Luque instrumentation. Twenty-three patients had staged scoliotic procedures. Overall there was a 47% incidence of complications, with the lowest rate, 20%, found in those patients undergoing single-stage posterior fusion with Luque instrumentation. A 16.7% incidence of pseudarthrosis was found in those patients undergoing posterior fusion with Harrington instrumentation. Pseudarthrosis was not found in patients fused posteriorly with Luque instrumentation or with staged anterior and posterior instrumentation.

Adult↗
PubMed1985

Surgical fusion of the posttraumatic spine: a radiologic assessment.

Radiological assessment of surgical fusion of fractures and dislocations of the cervical, thoracic, and lumbar spine are an integral part of management of spinal cord injury patients. A meaningful assessment of such fusions can be done properly only when there is adequate knowledge of the types of surgical fusions, the biological material used, and metallic devices applied. Early surgical reduction and internal fixation of the traumatized spine facilitate rapid restoration of spinal alignment, make nursing care less difficult, and sometimes lead toward improvement of neurological function. Complications can occur in all types of surgical fusions. They can affect the fusion material, the metallic device, or the alignment of the spine. Most of those complications are radiologically detected.

Bone Nails↗
PubMed1984

Relationship between past academic performance and results of specialty in-training examinations.

In this study, the authors review the records of 63 graduates of Northwestern University Medical School who were residents in its graduate medical education programs of anesthesia and orthopedic surgery. They examine the relationship among college grades, medical school performance, and the results of assessment by annual, nationwide, medical specialty in-training examinations. For the anesthesia group, the best predictors of in-training examination performance were the Medical College Admission Test (MCAT) Verbal Ability score, the college grade-point average for nonscience subjects, and the MCAT Science, General Information, and Quantitative Ability scores. For the orthopedic group, the best predictors were the MCAT Verbal Ability score, the college grade-point average in nonscience subjects, the MCAT Science score, and the National Board of Medical Examiners Part I and Part II examination scores. The previous academic records for the 63 residents contained little to presage results in the in-training examination. The correlation obtained between nonscience college subjects and the in-training examination results was negative.

Achievement↗
PubMed1984

Chymopapain allergy: case reports and identification of patients at risk for chymopapain anaphylaxis.

Chymopapain has been approved for intradiscal injection in the United States and is expected to be used in approximately 100,000 patients per year. The need to identify the population at risk for anaphylaxis is obvious. Both in vivo and in vitro methods are available for measurement of IgE against chymopapain. This is a report of two cases of chymopapain allergy. One case discusses a 25-year-old woman who had rhinitis, asthma, and urticaria associated with occupational health hazards who was rejected for chemonucleolysis. The other case describes a 59-year-old man who had a predictably severe anaphylactic reaction to chymopapain and responded to treatment with epinephrine. Both patients had IgE antibody against chymopapain.

Adult↗
PubMed1983

Thoracic and lumbar spine fusion: postoperative radiologic evaluation.

A retrospective review of 206 consecutive thoracic and lumbar fusions revealed a variety of surgical procedures performed for instability and malalignment after severe trauma. Stabilization procedures included insertion of 103 Harrington distraction and 15 Harrington compression rods, 84 Weiss spings, six Luque rods, and 10 miscellaneous plates and wires as single or multiple devices in combination with anterior and/or posterior fusions. Complications of surgical fusion included nine unhooked rods, six fatigue fractures of rods and springs, five overdistractions of vertebrae, four cases of severe kyphosis, and two failures of reduction. A meaningful postoperative radiologic evaluation can be accomplished only when indications for surgical techniques, their radiologic appearance, and possible complications are known.

Adolescent↗
PubMed1983

Professional behavior in the orthopedic resident. A method for evaluation and development.

The affective behavior of orthopedic residents may be the most important indicator of their ability to function as orthopedic surgeons. Seven years of personal observations were combined with the experience of more than 300 participants in the Basic Course for Orthopaedic Educators, and recorded from the results of a recent questionnaire answered by members of the Association of Orthopaedic Chairmen. The affective domain was found to supply the answers to most of the problems of orthopedic residents. An evaluation of affective behavior early in the residency program may help to determine residents' suitability for a career in orthopedic surgery.

Affect↗
PubMed1978

Dwyer instrumentation of the spine.

The evolution of the Dwyer procedure during the past 10 years has enabled us to better define the indications and contraindications for the procedure. The role of the Dwyer procedure in the treatment of thoracolumbar or lumbar curves in both the adolescent and the adult has been found to be significant. When combined with Harrington rod instrumentation it can be used for either paralytic curves, curves associated with pelvic obliquity, or curves in which posterior elements are absent.

Child↗
PubMed1978

Rational approach to the differentiation of vascular and neurogenic claudication.

Lower extremity pain caused by exercise but relieved by rest is usually a reliable symptom of chronic arterial insufficiency. However, similar discomfort often occurs in patients with neurospinal compression. Furthermore, arterial occlusive disease and demonstrable spinal stenosis may be present simultaneously. Fifty-two patients with symptoms suggesting intermittent claudication comprised the study group. All were proven to have a nonarterial cause of their complaint. The study consists of a retrospective analysis of the diagnostic methods used in confirming the proper diagnosis. Conclusions reached suggest a rational approach to solution of individual patient problems. The nonvascular origin of the symptoms was suggested initially by clinical evaluation in 19 patients, and by noninvasive arterial evaluation in an additional 22. The neurospinal origin of symptoms was obscured in 11 patients because of the presence of significant arterial occlusive disease, as demonstrated by nominvasive arterial testing. Seven of the 11 patients underwent arterial reconstruction, which failed to relieve their symptoms. Subsequently, the neurospinal origin of these symptoms was proven by appropriate treatment. This experience has shown that the errors in diagnosis and treatment could have been avoided by using a combined diagnostic approach, correlating results of an accurate clinical evaluation with noninvasive arterial testing as well as the findings shown on lumbosacral spine films.

Adult↗
PubMedDate not supplied

Modification of Cotrel-Dubousset's original hook constructs for idiopathic scoliosis.

We performed a retrospective review of 41 patients (ages 9-18 years) who underwent posterior spinal fusion with either Isola or Cotrel-Dubousset (CD) instrumentation to determine whether the presence of an apical hook on the thoracic convexity affected initial and long-term sagittal and coronal correction in adolescent idiopathic scoliosis surgery. A study group of 38 female and three male patients was evaluated (2-5 years of follow-up). Twenty-three patients (Group A) were treated with an up-going hook at the convex apex of the thoracic curve, and 18 patients (Group B) with similar curves were instrumented without an apical hook. Results showed that Group A's average preoperative coronal curve of 48 degrees decreased to 17 degrees , whereas Group B's preoperative average of 52 degrees decreased to 25 degrees . At follow-up, no statistical significance was noted in either coronal curve correction (p = 0.203) or sagittal kyphosis (p = 0.38) between Groups A and B. We conclude that omission of the up-going hook at the apex of the thoracic convexity can reduce postoperative discomfort in patients undergoing posterior spinal fusion, without sacrificing curve correction or balance.

Adolescent↗