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Biomedical subjects

J G Heller

Publications and source records attributed to J G Heller.

7 recordsLinked to original sources
PubMed1992

Morphology of the dens. A quantitative study.

Morphometric studies of the dens of the second cervical vertebra were performed on a sample of one hundred twenty bones from the Hamann-Todd Collection. Data were collected on the longitudinal and transverse dimensions of the dens, as well as the size of the dens relative to the centrum of C2. Relationships of dens dimensions to body size and sexual dimorphism were evaluated. In both longitudinal and transverse mean dimensions, the dens in males was slightly, but significantly larger (5-10%) than in females. The relative distributions of dens dimensions were consistently skewed toward the higher values in males and the lower values in females. Body height or weight were not significantly correlated with dens dimensions, and were therefore poor predictors of the size of the dens. Implications for screw fixation of fractures of the dens are discussed.

Adult↗
PubMed1992

Quantitative internal dens morphology.

Recent work has demonstrated the highly variable and unpredictable external dimensions of the dens (odontoid process). No data have been available regarding internal dimensions. Quantitative computed tomography analysis of 120 axis vertebrae allowed nondestructive measurement of external and internal dens dimensions. The external computed tomography measurements correlated well with caliper-derived data. Minimum internal dens dimensions and cortical thicknesses in the sagittal and transverse planes are reported. Some axis vertebrae may not be amenable to internal fixation of type II dens fractures. Preoperative planning should include quantitative computed tomography analysis of the dens.

Adult↗
PubMed1992

Disk herniations associated with compression instrumentation of lumbar flexion-distraction injuries.

Flexion-distraction injuries are often treated by open reduction and fusion using compression instrumentation. Three cases that were complicated by disk herniation at the injured level, with an acquired neurologic deficit, are reported. Middle-column failure through the annulus fibrosis (Gertzbein and Court-Brown Type A) appeared to be a common feature. This may be a permissive condition for this complication as compression is applied across the torn annulus. Preoperative magnetic resonance imaging and postreduction myelography may identify such herniations. Acquired neurologic deficits after reduction and instrumentation demand emergent evaluation and treatment.

Adolescent↗
PubMed1992

Postoperative posterior spinal wound infections.

The incidence of postoperative spinal infections increases with the complexity of the procedure. Diskectomy is associated with less than a 1% risk of infection; spinal fusion without instrumentation is associated with a 1%-5% risk; and fusion with instrumentation may be associated with a risk of 6% or more. Twenty-two postoperative posterior spinal infections that occurred during a three-year period were reviewed for this report. Staphylococcus aureus was the most frequent organism cultured (more than 50% of the cases). Other recurring organisms were Staphylococcus epidermis, Peptococcus, Enterobacter cloacae, and Bacteroides. Many patients had multiple organisms. Risk factors appeared to include advanced age, prolonged hospital bed rest, obesity, diabetes, immunosuppression, and infection at remote sites. Operative factors included prolonged surgery (greater than five hours), high volume of personnel moving through the operating room, and instrumentation. Postoperative contamination may occur and may be related to prolonged postoperative bed rest, skin maceration (thoracolumbosacral orthoses), and drainage tubes exiting distally from lumbar wounds (toward the rectum). Effective treatment includes early diagnosis, surgical debridement and irrigation, and parenteral antibiotics. Superficial infections were treated successfully with wound closure over outflow tubes, and deep infections with inflow-outflow systems. Maintaining the instrumentation in place was possible in most cases. Parenteral antibiotics were maintained for six weeks in every case.

Anti-Bacterial Agents↗
PubMed1992

The syndromes of degenerative cervical disease.

Senescence of the cervical spinal motion segment is manifest by changes in each anatomic component. The pathoanatomical change that predominates varies from one person to the next. Sufficient compromise of local neural structures will precipitate the onset of symptoms. The pattern of symptoms and any associated physical signs will vary according to which structures are stimulated or compressed. Radicular and myelopathic syndromes are produced by nerve root and spinal cord compression, respectively. These patterns can occur individually or in combination. Other less clearly understood patterns of local and referred symptoms may be mediated by the sinu-vertebral nerves or the medial branches of the posterior ramus. Techniques for the precise diagnosis of these syndromes are needed. Separating patterns of symptomatic degenerative cervical disease from other causes of neck, shoulder, and arm symptoms rests on an awareness of the broad spectrum of subjective complaints, a thorough physical examination, and confirmatory diagnostic studies. Clear delineation of the etiology will increase the likelihood of successful treatment.

Aging↗
PubMed1991

Anatomic comparison of the Roy-Camille and Magerl techniques for screw placement in the lower cervical spine.

The Roy-Camille and Magerl techniques for screw placement in the lower cervical spine were compared under simulated operating room conditions. Three surgeons with varying years of spine surgery experience participated. The anatomic morbidity risks of each screw insertion technique were evaluated by anatomic dissection and radiographic examination. The spinal cord and vertebral arteries were not threatened by either method. Analysis of the pooled data revealed that the Roy-Camille technique had less risk of nerve root injury, nerve roots placed "at risk" for injury, and errors in "zone" of placement. The Magerl technique had less risk of facet joint violation. A learning curve was observed. Once the surgeons gained experience with the two techniques, there were no longer any statistically significant differences among them. The number of years of spine surgery practice did not influence the morbidity risk of either technique. The surgeons' ability to aim the screws was identical in the axial plane, but consistently less accurate in the sagittal plane for the Magerl screws because of the normal prominence of the cervicothoracic junction. Thorough familiarity with the regional anatomy and practice in the anatomy laboratory are recommended before performing these techniques in patients.

Bone Screws↗