Biomedical subjects

E J Wall

Publications and source records attributed to E J Wall.

At least 19 recordsLinked to original sources

PubMed2006

Spinal hemiepiphysiodesis correlates with physeal histomorphometric gradients.

Compression of a growth plate is known to correlate with changes to growth plate structure. The purpose of this study was to determine if the height of the physeal hypertrophic zones and chondrocyte size were directly related to the distance from a spine implant. The implant was designed with the goal of slowing spine growth asymmetrically. For stapled vertebrae, hypertrophic zone height, cell height and cell width were decreased across the coronal plane of the growth plate, with the lowest values under the staple, 8 weeks postoperatively.

Biomechanical Phenomena↗

PubMed2006

Bilateral intra-annular spinal compressive stresses in vivo.

The purpose of this pilot study was to determine if compressive stresses in the annulus of the intervertebral disc vary with activity in a quadruped and are affected by treatment with an implant. Pilot in vivo tests were conducted on skeletally immature domestic pigs (approved by IACUC). One pair of sensors was implanted within the annulus of T10-11, and the second pair at T8-9. A staple was them implanted across the right side of T8-9. Wires were routed subcutaneously and exited at the dorsal cervical region. Sensor signals were acquired before and after staple implantation, post-operatively during normal activities, and biweekly under anesthesia. After 8 weeks, spines were harvested and imaged. Early results from 2 sensors during walking and sitting, post-op day 5, clearly showed cyclic stresses during gait. Stresses were attenuated at the stapled vertebra compared to the unstapled vertebra.

Animals↗

PubMed2001

The effect of surgical timing on the perioperative complications of treatment of supracondylar humeral fractures in children.

BACKGROUND: The purpose of this study was to evaluate the perioperative complication rates associated with early surgical treatment (eight hours or less following injury) and delayed surgical treatment (more than eight hours following injury) of displaced supracondylar humeral fractures in children. METHODS: Fifty-two patients had early surgical treatment and 146 patients had delayed surgical treatment of a displaced supracondylar humeral fracture. The perioperative complication rates of the two groups were compared with the use of bivariate and multivariate statistical methods. RESULTS: There was no significant difference between the two groups with respect to the need for conversion to formal open reduction and internal fixation (p = 0.56), pin-track infection (p = 0.12), or iatrogenic nerve injury (p = 0.72). No compartment syndromes occurred in either group. Power analysis revealed that our study had an 86% power to detect a 20% difference between the two groups if one existed. CONCLUSIONS: We were unable to identify any significant difference, with regard to perioperative complication rates, between early and delayed treatment of displaced supracondylar humeral fractures. Within the parameters outlined in our study, we think that the timing of surgical intervention can be either early or delayed as deemed appropriate by the surgeon.

Adolescent↗

PubMed2000

The accuracy of oral predictive and infrared emission detection tympanic thermometers in an emergency department setting.

OBJECTIVE: To assess the accuracy of an oral predictive thermometer and an infrared emission detection (IRED) tympanic thermometer in detecting fever in an adult emergency department (ED) population, using an oral glass mercury thermometer as the criterion standard. METHODS: This was a single-center, nonrandomized trial performed in the ED of a metropolitan tertiary referral hospital with a convenience sample of 500 subjects. The temperature of each subject was taken by an oral predictive thermometer, an IRED tympanic thermometer set to "oral" equivalent, and an oral glass mercury thermometer (used as the criterion standard). A fever was defined as a temperature of 37.8 degrees C or higher. The subject's age, sex, triage category, and diagnostic group were also recorded. Sensitivity, specificity, positive and negative likelihood ratios, positive and negative predictive values, and corresponding 95% confidence intervals were calculated. Logistic regression was used to identify predictors of fever. RESULTS: The sensitivities and specificities for detection of fever of the predictive and the IRED tympanic thermometers were similar (sensitivity 85.7%/88.1% and specificity 98.7%/95.8%, respectively). The predictive thermometer had a better positive predictive value (85.7%) compared with the IRED tympanic thermometer (66.1%). The positive and negative likelihood ratios for the predictive oral thermometer were 65 and 0.14, respectively, and for the IRED tympanic thermometer 21 and 0.12, respectively, indicating that the predictive thermometer will "miss" 1 in about 7 fevers and the IRED tympanic thermometer will "miss" 1 in about 8 fevers. CONCLUSIONS: Although quick and convenient, oral predictive and IRED tympanic thermometers give readings that cannot always be relied on in the detection of fever. If we are to continue using electronic thermometers in the ED setting, we need to recognize their limitations and maintain the importance of our clinical judgment.

Emergency Service, Hospital↗

PubMed2000

Practical primary pediatric orthopedics.

Pediatric orthopedic problems often puzzle the primary health provider and worry families. A thorough orthopedic history and examination by the primary care provider is all that is necessary to determine whether a problem requires further evaluation and referral. This article addresses a practical approach to common orthopedic problems, assessment, and management strategies from the specialist perspective. A general description of developmental dysplasia of the hip, foot misalignments, tibial torsion, toe-walking, genu varum (bowlegs), growing pains, sprains and fractures, and the child with a limp is provided. Management strategies before and after orthopedic referral are presented.

Child↗

PubMed2000

Traumatic hip dislocation in children. Long-term followup of 42 patients.

To assess the impact of traumatic hip dislocations in the skeletally immature patient, 42 children younger than 16 years of age (average age, 9 years 10 months) who were treated at the authors' institution were studied. Data were collected from charts and radiographs and by completion of questionnaires. The average followup after injury was 10 years 1 month. The majority of dislocations (64%) were attributable to low energy injuries. Ipsilateral fractures about the hip occurred in 17% of patients. Avascular necrosis of the femoral head developed in 12% of patients, with the amount of time spent dislocated being the only statistically proven risk factor. Patients whose reduction was delayed greater than 6 hours had a 20 times higher risk of having avascular necrosis develop compared with patients whose hips were reduced in 6 hours or less. The use of computed tomography for joint asymmetry of 3 mm or greater and omission of bone scan screening were supported by this study. Functional outcomes were very good in this series with 95% of patients suffering mild (usually weather related) or no pain and 95% of patients suffering mild pain (intermittently noticeable) or no limp. A large percentage of the patients (78%) continued to participate in high demand activities such as football, soccer, and basketball.

Adolescent↗

PubMed1999

Video-assisted thoracoscopy.

New therapeutic modalities for disorders of the pediatric spine must include video-assisted thoracoscopy. The endoscopic approach to the spine has involved an evolutionary approach. What began as an isolated drainage of a vertebral abscess was continued as a method of single discectomy; release of the annulus fibrosis with or without ligation of segmental vessels; rib resection for costoplasty; rib harvesting for intervertebral fusion; and most recently, insertion of correctional implants and fusion.

Adolescent↗

PubMed1999

Legg-Calvé-Perthes' disease.

The etiology, radiographic classification, and treatment of Legg-Calvé-Perthes' disease remain controversial. Several recent papers focus on these issues in an effort to provide guidance in the clinical care of Perthes' disease. The research studied in this paper lends further support to the hypothesis of clotting abnormalities with vascular thrombosis, which seems to be the most likely etiology for Legg-Calvé-Perthes' disease. Several studies focus on use of magnetic resonance imaging for the early diagnosis and prognosis of Perthes' disease. A few researchers whose work is featured in this paper add information on the treatment of Perthes' disease, supporting surgical treatment for older patients with more severe disease and non-surgical treatment for younger patients with less extensive femoral head involvement.

Child↗

PubMed1998

Endoscopic discectomy increases thoracic spine flexibility as effectively as open discectomy. A mechanical study in a porcine model.

STUDY DESIGN: Two surgical techniques for anterior discectomy were compared biomechanically. The surgical procedures were performed in live, anesthetized, skeletally immature pigs. Spine flexibility was measured in vitro. OBJECTIVE: To determine whether endoscopic techniques for discectomy are as effective as open procedures in increasing spine flexibility. SUMMARY OF BACKGROUND DATA: Although studies have verified that discectomy increases spine flexibility, no study has confirmed whether endoscopic techniques increase flexibility as effectively as standard thoracotomy, which is a substantially different procedure. METHODS: The intervertebral disc between vertebrae T8 and T9 was resected from 30 live, anesthetized, adolescent pigs. In 15 pigs, the chest was opened via thoracotomy of the eighth rib, and the disc was excised. In the other 15 pigs, the disc was removed endoscopically. These motion segments and six intact controls were tested mechanically in side bending, flexion-extension, and axial rotation. RESULTS: No statistically significant differences in flexibility were found between open and endoscopic groups in any loading direction. The statistical power to detect a 20% difference between surgical groups was > or = 95%. CONCLUSIONS: Endoscopic and open techniques were equally effective in increasing spine flexibility. Because endoscopy may reduce surgical morbidity compared with open discectomy, these results support the use of endoscopy for the surgical correction of scoliosis before instrumentation.

Animals↗

PubMed1998

Childhood osteomyelitis and septic arthritis.

The diagnosis, treatment, and monitoring of septic arthritis or osteomyelitis in children has become more streamlined in recent years. C-reactive protein appears to be a better laboratory study than sedimentation rate in the diagnosis of bone or joint infection and in monitoring a patient's clinical response to antibiotics. Oral antibiotics may be rapidly substituted for intravenous antibiotics in patients who have a identifiable sensitive organism, who show rapid clinical improvement, and who show rapid normalization of C-reactive protein. The physician must remain alert for resistant organisms, highly virulent organisms (post-varicella streptococcal infections) and rare organisms.

Anti-Bacterial Agents↗

PubMed1992

Experimental stretch neuropathy. Changes in nerve conduction under tension.

We developed an animal model of stretch injury to nerve in order to study in vivo conduction changes as a function of nerve strain. In 24 rabbits, the tibial nerve was exposed and stretched by 0%, 6% or 12% of its length. The strain was maintained for one hour. Nerve conduction was monitored during the period of stretch and for a one-hour recovery period. At 6% strain, the amplitude of the action potential had decreased by 70% at one hour and returned to normal during the recovery period. At 12% strain, conduction was completely blocked by one hour, and showed minimal recovery. These findings have clinical implications in nerve repair, limb trauma, and limb lengthening.

Action Potentials↗

PubMed1992

Strain, stress and stretch of peripheral nerve. Rabbit experiments in vitro and in vivo.

Mechanical stretching is known to cause morphologic and functional changes in peripheral nerve. The points at which these changes occur, however, are not clearly defined and reported data are conflicting. The studies presented in this paper provide a basic understanding of the biomechanical properties, stretch-injury patterns, and changes of conduction properties of peripheral nerves due to stretching. Our studies showed that peripheral nerves exhibited non-linear stress-strain characteristics when placed under tension. Initially, under tension, the nerve had a low modulus that increased gradually with increasing strain until reaching a maximal value. When the nerve failed under tension, the perineurium inside the nerve ruptured, but the exterior of the nerve remained intact. Our results also show that a peripheral nerve in situ was under significant strain, but minimal in situ stress (less than 0.05 MPa). The in situ strain might vary with limb position, but did not appear to exceed the limit beyond which substantial tension or stress would be developed in the nerve. The time-dependent viscoelastic behavior of peripheral nerves were also characterized. The maintenance of small in situ stresses suggests that sustained increases in tension could be adversely affecting the electrophysiologic properties of the nerve. Indeed, marked alteration of conduction properties resulted from even a small stretch of 6 percent beyond the in situ length of the nerve, or stress less than 10 percent of the ultimate strength of the nerve.

Animals↗

PubMed1991

Stress relaxation of a peripheral nerve.

This study determines the change in tension after an acute nerve lengthening, as would occur in peripheral nerve repair. Stress relaxation, a viscoelastic property, was studied with the use of 24 rabbit tibial nerves. The nerves were divided into three groups and were stretched 6%, 9%, or 12% beyond their original resting length. The mean 1-hour stress relaxations for the three groups were 48%, 34%, and 34%, respectively. Nerve stress relaxation was significantly greater at 6% strain than at 9% or 12% strain. These biomechanical findings have important clinical implications for nerve-stretch injury and for nerve repair.

Animals↗

PubMed1991

The anatomy of the cauda equina on CT scans and MRI.

The nerve roots of the cauda equina may be visualised by contrast-enhanced CT scans and by surface-coil MRI. We have identified the pattern of anatomy from L2-L3 to L5-S1 in 10 human cadaver specimens and correlated this with anatomical dissections. Individual roots are slightly more distinct on contrast-enhanced CT than on surface-coil MRI. There is a crescentic oblique pattern of nerve roots at the lower lumbar levels which is still apparent in the more crowded proximal sections. In all cases, the axial images correlated precisely with the dissections. Current imaging modalities can help the clinical understanding and management of abnormalities in this region of the spine.

Adult↗

PubMed1990

Cauda equina anatomy. I: Intrathecal nerve root organization.

The three-dimensional organization of the human cauda equina has not been described previously. This is partly due to the difficulties of dissecting individual, unfixed nerve roots. By the use of a newly developed in situ fixation and embedding technique on 15 fresh human cadavers, the cross-sectional anatomy of the cauda equina was defined from L2-L3 to L5-S1. A highly consistent cross-sectional pattern was observed in all specimens. The lower sacral (S2-S5) and coccygeal roots were located in the dorsal aspect of the thecal sac, whereas the lumbar and first sacral roots exhibited an oblique, layered pattern as they ascended. The motor bundle was situated anteromedial to its respective sensory bundle within each layer, Invaginations of arachnoid held the nerve roots in a fixed relationship to one another. This previously undescribed three-dimensional anatomy within the thecal sac may aid in the understanding and treatment of trauma, neurocompressive syndromes, and tumors of the cauda equina.

Aged↗

PubMed1990

Organization of intrathecal nerve roots at the level of the conus medullaris.

The three-dimensional organization of the spinal nerve roots at the level of the conus medullaris has not been described previously, to our knowledge. In this study, we used a newly developed technique of in situ fixation and embedding to define the cross-sectional anatomy at the level of the conus medullaris in ten fresh human cadavera. A highly organized overlapping pattern of nerve roots was demonstrated in all specimens. The nerve roots form a peripheral rim around the spinal cord at the levels of the tenth and eleventh and the eleventh and twelfth thoracic intervertebral discs. More caudally, the cord diminishes in size and the nerve roots predominate. The most cephalad roots lie laterally, with the motor roots ventral to their sensory counterparts. The more caudad roots overlap toward the midline, and the motor and sensory portions of each root are separated by spinal cord tissue. An intricate web of arachnoid membrane holds the nerve roots in a fixed relationship to each other.

Aged↗

PubMed1990

1990 AcroMed Award in basic science. Cauda equina anatomy. II: Extrathecal nerve roots and dorsal root ganglia.

Inconsistent data exist regarding the anatomy of the spinal nerve roots lateral to the thecal sac. A newly developed in situ technique was used to precisely define anatomic parameters on 20 fresh human cadavers. The take-off angle of the nerve roots from the thecal sac decreases from a mean of approximately 40 degrees from L1-L5 to 22 degrees at S1. The motor bundles are directly ventral to the sensory fibers within individual roots extrathecally. Dorsal root ganglia size varies with vertebral level. The majority of ganglia lie directly beneath the vertebral pedicles and one third overlie a portion of the lateral intervertebral disc. These previously undescribed relationships may aid in the understanding of lumbosacral neurocompressive disorders and are important to note during pedicle screw insertion, posterolateral decompression for spinal trauma, and paravertebral approaches for lateral disc herniations.

Aged↗

PubMedDate not supplied

Endoscopic pelvic osteotomy for the treatment of hip dysplasia.

Adolescent and adult hip dysplasia can be surgically treated by rotating the acetabulum into a better weight-supporting position; however, open pelvic osteotomies are among the most invasive of all pediatric orthopaedic procedures. Endoscopic pelvic osteotomy offers the theoretical advantages of magnified visualization of the bone cuts, minimized surgical dissection, and rapid postoperative recovery. The technique of endoscopically assisted triple innominate osteotomy requires the combination of endoscopic skills and facility with more standard surgical approaches.

Endoscopy↗