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Biomedical subjects

W F Donaldson

Publications and source records attributed to W F Donaldson.

At least 19 recordsLinked to original sources
PubMed1999

Degenerative lumbar listhesis and bone mineral density in elderly women. The study of osteoporotic fractures.

STUDY DESIGN: A cross-sectional and prospective study. OBJECTIVES: To investigate the association between lumbar listhesis in elderly white women and bone mineral density at the spine, hip, radius, and calcaneus. SUMMARY OF BACKGROUND DATA: Several types of degenerative spinal changes have been found to be associated with high bone mineral density at the spine and other body sites. METHODS: Lateral radiographs of the lumbar spine for 1400 elderly women enrolled in the Study of Osteoporotic Fractures were digitized. Listhesis (antero and retro) was assessed at L3-L4, L4-L5, and L5-S1. Bone mineral density was measured at the spine, hip, calcaneus, and the distal and proximal radius. RESULTS: After adjusting the data for age and body mass index, retrolisthesis at L3-L4, L4-L5, and L5-S1 was associated with mean spinal bone mineral density levels that were 9% to 13% higher compared with those levels in women with no listhesis (P < 0.0001). In addition, bone mineral density at the hip and appendicular sites increased from 4% to 9%. The mean lumbar spinal bone mineral density of women with anterolisthesis at L3-L4 was 12% higher (P < 0.05) than that of women with no listhesis; it was the same for both groups at L4-L5 and was 7% lower (P < 0.005) at L5-S1. At L5-S1 the bone mineral density level at the hip and appendicular sites was also lower among the women with anterolisthesis at that level. CONCLUSIONS: This study suggests that retrolisthesis, like other spinal degenerative diseases, is associated with increased spinal bone mineral density. Anterolisthesis, however, may involve a different etiology, because its association with bone mineral density varies by spinal level.

Aged↗
PubMed1998

Lumbar olisthesis and lower back symptoms in elderly white women. The Study of Osteoporotic Fractures.

STUDY DESIGN: A Cross-sectional study. OBJECTIVES: To determine the prevalence of lumbar olisthesis among white women aged 65 years and older and its relation to low back pain and back function. BACKGROUND: Degenerative changes in the lumbar spine of elderly individuals may affect spinal stability, causing olisthesis (subluxation) of the lumbar spine. Neither the prevalence of this condition in the United States nor its relation to back symptoms has been studied previously. METHODS: Lateral radiographs of the lumbar spine for 788 women aged 65 years and older who were enrolled in the Study of Osteoporotic Fractures were digitized. Olisthesis (antero- and retro-) was assessed at L3-L4, L4-L5, and L5-S1. Back pain and function also were assessed. RESULTS: When olisthesis was defined as subluxation of 3 mm or more at any of the three levels studied, the overall prevalence of anterolisthesis was 29% and that of retrolisthesis was 14%. In 90% of women with anterolisthesis and 88% of women with retrolisthesis, subluxation occurred at a single vertebral level. The prevalence of anterolisthesis and retrolisthesis did not vary by smoking status, presence of diabetes, or history of oophorectomy. Anterolisthesis was not associated with the presence of back symptoms. Only retrolisthesis at L3-L4 was associated with a statistically significantly increased likelihood of lower back pain, greater severity of back pain, and impairment of back function. CONCLUSIONS: Anterolisthesis of 3 mm or more in the lower lumbar spine is relatively common among elderly women but is not correlated with back problems. Retrolisthesis at L3-L4 is associated with increased back pain and impaired back function.

Aged↗
PubMed1998

Helmet and shoulder pad removal from a player with suspected cervical spine injury. A cadaveric model.

STUDY DESIGN: Video fluoroscopy was used to evaluate the motion in an unstable spine during helmet and shoulder pad removal. OBJECTIVE: To observe the amount of motion that occurs during the removal of helmet and shoulder pads in an injured spine. SUMMARY OF BACKGROUND DATA: Removal of shoulder pads and helmet from a football player with suspected cervical spine injury can be particularly hazardous. How much flexion occurs at the unstable level during removal of equipment is unknown. METHODS: Six fresh cadavers were used in the study. In three, an unstable C1-C2 segment was created by transoral osteotomy of the base of C2. In the remaining three, instability was created at C5-C6 by a posterior release. Under fluoroscopic recording, the helmets were removed by first removing the chin strap, face mask, and ear pieces. With the neck stabilized, the helmet was carefully removed. The shoulder pads were carefully removed, with the head stabilized. Angulation, distraction, and space available for the cord were measured at C1-C2. Translation, angulation, distraction, and change in disc height were measured in the specimens with unstable C5-C6. RESULTS: In cadavers with C1-C2 instability, the mean change in angulation was 5.47 degrees, and space available for the cord was 3.91 mm. Shoulder pads were removed while the head was stabilized. The mean change in angulation at C1-C2 was less during removal of shoulder pads than during helmet removal at 2.9 degrees. Space available for the cord was 2.64 mm. Distraction was also greater during helmet removal (2.98 mm) than during shoulder pad removal (1.76 mm). In the unstable spine, the change in displacement in translation was greater during shoulder pad removal (3.87 mm), than during helmet removal (0.41 mm). Disc height change was similar. Distraction of the spinous processes was greater during helmet removal (3.68 mm) than during shoulder pad removal (1.37 mm). Angulation was similar in both maneuvers. CONCLUSIONS: Helmet and shoulder pad removal in the unstable cervical spine is a complex maneuver. In the unstable C1-C2 segment, helmet removal causes more angulation in flexion, more distraction, and more narrowing of the space available for the cord. In the lower cervical spine (C5-C6), helmet removal causes flexion of 9.32 degrees, and during shoulder pad removal the neck extends 8.95 degrees, a total of approximately 18 degrees. Disc height changes from 1.24 mm of distraction to 1.06 mm of compression during helmet removal and shoulder pad removal for a total 2.3-mm change. Translation, which correlates with the change in the space available for the cord, is greater at C5-C6 during shoulder pad removal. Because most of the cadavers had C5 anteriorly displaced on C6 to begin with, the extension force during shoulder pad removal caused a 3.87-mm change in reduction of C5 on C6. Because of the motion observed in the unstable spine, helmet and shoulder pad removal should be performed in a carefully monitored setting. They should be removed together by at least three, preferably four, trained people.

Cadaver↗
PubMed1998

Correlation of late intraforaminal screw removal with somatosensory evoked potentials and neurologic improvement.

This case report describes the intraoperative improvement of somatosensory evoked potentials (SEPs) during the removal of a broached pedicle screw that had been placed in an unmonitored procedure 1 month earlier. Postoperatively, there was improved neurologic function and reversal of the neurologic deficit that had been caused by the first procedure. To our knowledge, this is the first report of a correlation of intraoperative SEP improvement with improved postoperative neurologic function after neurologic deficit because of nerve irritation or compression from a pedicle screw. Nerve damage occurs in about 15% of patients who undergo instrumentation after lumbar fusion. The potential utility of neurophysiologic methods during initial screw placement is suggested and supported, as proper use of such intraoperative tools may have prevented the need for the second procedure.

Adult↗
PubMed1997

The effect of airway maneuvers on the unstable C1-C2 segment. A cadaver study.

STUDY DESIGN: This is a cadaver study in which video fluoroscopy is used to measure motion of the unstable spine at C1-C2 during intubation maneuvers. OBJECTIVES: To quantify the amount of motion that occurs at an unstable C1-C2 spinal segment during the use of various intubation techniques using a cadaver model. SUMMARY OF BACKGROUND DATA: In previous work by the authors, a methodology and measurements for the unstable C5-C6 segment in a cadaver model were developed. These studies showed that the most motion was created by a chin lift and jaw thrust and that oral techniques created more motion than nasal intubation. The potential motion that occurs during intubation with instability at C1-C2 is yet unstudied. Therefore, a study to determine the effects of intubation on the spine with an unstable C1-C2 segment was designed. METHODS: Six human cadavers were used for the study. Measurements before and after transoral osteotomy of the odontoid were performed using video fluoroscopy. Pre-intubation maneuvers and oral and nasal intubation were studied. RESULTS: Oral intubation and nasal intubation caused similar diminution of space available for the cord. Chin lift and jaw thrust caused a larger diminution of space available for the cord than either nasal or oral intubation techniques. CONCLUSIONS: Although nasal intubation is the accepted procedure for intubation of the unstable spine, nasal and oral intubation seemed to have the same ability to narrow the space available for the cord in the model in this study. Great care should be taken while performing the chin lift/jaw thrust maneuvers in preparation for intubation, because these pre-intubation techniques caused the most motion and hence narrowed the space available for the cord in the unstable cervical spine.

Cadaver↗
PubMed1996

Herniated lumbar intervertebral discs spontaneously produce matrix metalloproteinases, nitric oxide, interleukin-6, and prostaglandin E2.

STUDY DESIGN: Herniated lumbar disc specimens were obtained from patients undergoing surgical discectomy for persistent radiculopathy and cultured in vitro to determine whether various biochemical agents were being produced. OBJECTIVES: Our hypothesis is that biochemical mediators of inflammation and tissue degradation play a role in intervertebral disc degeneration and in the pathophysiology of radiculopathy. SUMMARY OF BACKGROUND DATA: Low back pain with or without radiculopathy is a significant clinical problem, but the etiology of low back pain and the exact pathophysiology of radiculopathy remain elusive. The biochemical events that occur with intervertebral disc degeneration and, in particular, the role of biochemical mediators of inflammation and tissue degradation have received sparse attention in the literature. There is some preliminary evidence that inflammatory mediators may have an important role in the pathophysiology of radiculopathy. METHODS: Eighteen herniated lumbar discs were obtained from 15 patients undergoing disc surgery. The specimens were cultured and incubated for 72 hours, and the media were collected subsequently for biochemical analysis. Biochemical assays for matrix metalloproteinases, nitric oxide, prostaglandin E2, and a variety of cytokines were performed. As a control group, eight lumbar disc specimens were obtained from four patients undergoing anterior surgery for scoliosis and traumatic burst fractures, and similar biochemical analyses were performed. RESULTS: The culture media from the herniated lumbar discs showed increased levels of matrix metalloproteinase activity compared with the control discs. Similarly, the levels of nitric oxide, prostaglandin E2, and interleukin-6 were significantly higher in the herniated discs compared with the control discs. Interleukin 1 alpha, interleukin-1 beta, tumor necrosis factor-alpha, interleukin-1 receptor antagonist protein, and substance P were not detected in the culture media of either the herniated or control discs. CONCLUSIONS: Herniated lumbar discs were making spontaneously increased amounts of matrix metalloproteinases, nitric oxide, prostaglandin E2, and interleukin-6. These products may be involved intimately in the biochemistry of disc degeneration and the pathophysiology of radiculopathy. Their exact roles certainly need further investigation, but their mere presence implicates biochemical processes in intervertebral disc degeneration.

Adult↗
PubMed1996

Percutaneous biopsy of the thoracic spine.

Percutaneous biopsy of the thoracic spine has become the procedure of choice for biopsy of the thoracic spine. Familiarity with triangulation and using biplane fluoroscopy or the CT scan is a requirement, however. Once these techniques have been mastered, biopsy of the thoracic spine is safe and effective for obtaining diagnostic tissue and only under rare circumstances is opened biopsy necessary. The technique is described as is a review of the results.

Biopsy, Needle↗
PubMed1993

A methodology to evaluate motion of the unstable spine during intubation techniques.

Airway management in patients with an unstable cervical spine remains a challenge. A video fluoroscopic technique that transfers the image to a floppy disk for direct measurement is described. This technique enabled standardized, direct measurement of the cervical spine during airway maneuvers before and after a C5-6 posterior instability was surgically created in five cadaveric specimens. Unsupported direct oral techniques often can cause more motion than do indirect nasal techniques, and chin lift/jaw thrust and cricoid pressure can cause as much motion as do some of the intubation techniques.

Cadaver↗
PubMed1993

Percutaneous biopsy in the anterior thoracic spine.

Over a 24-month period, seven patients have undergone nine diagnostic closed percutaneous biopsies of thoracic vertebral body lesions. Seven of the nine biopsies were performed using the Craig trephine biopsy set. All seven biopsies provided diagnostic material. Two biopsies were performed with 22-gauge needles and aspiration technique. One provided diagnostic material. The only complication was a small pneumothorax that spontaneously resolved. Current editions of orthopedic texts give mixed recommendations as to the route of vertebral body biopsy in the thoracic spine. Most recommend open rather than percutaneous biopsy, particularly above T10. Review of current orthopedic literature, however, reveals overwhelming support for the use of closed biopsy techniques as the procedure of choice for tissue diagnosis of thoracic vertebral body lesions. As in this limited series, the reported positive biopsy ratio is high and the complication rate acceptably low.

Adolescent↗
PubMed1993

Symptomatic metastatic malignant melanoma to the spine.

Fifteen patients with symptomatic metastatic melanoma were retrospectively reviewed. All patients had severe back pain, and seven presented with neurologic findings. The interval between spinal involvement and death was 5.9 months (range 3 weeks to 24 months). The average survival after onset of neurologic signs was 3.5 months (range 3 weeks to 7 months). In the seven patients with neurologic involvement, the average survival for the four who had surgery was 5.25 months (range 3-7 months) from the onset of symptoms and 1.2 months (range 2 weeks to 3 months) for those who did not have surgery. This dismal prognosis must be considered along with the magnitude and morbidity of any spinal procedure, the adverse impact on quality of life from neurologic compromise, and the relative failure of medical therapy for melanoma.

Adult↗
PubMed1993

Surgical treatment for the far lateral herniated lumbar disc.

Twenty-nine patients underwent surgery for far lateral herniated nucleus pulposus. Average patient age was 65 years in the 14 male and 15 female patients involved. The L4-5 disc was the most commonly herniated level (59%) followed by L3-4 (31%), L5-S1 (7%), and L2-3 (3%). All patients were initially seen with radiculopathy and 23 patients (79%) had motor weakness. A pars interarticularis sparing technique is described for approaching this type of disc herniation. This approach allows direct visualization of the disc and involved root. The results are encouraging with 72% of patients having good or excellent relief of pain. Seventy-one percent of those with preoperative weakness had no weakness or improvement in strength postoperatively. In general, far lateral herniated nucleus pulposus occurs in older patients and at high lumbar disc levels. Postoperative results are similar to the more common posterolateral herniated nucleus pulposus in patients of the same age group. A surgical approach is described to better address the less familiar anatomy.

Adult↗
PubMed1993

Cervical spine surgery in rheumatoid arthritis: improvement of neurologic deficit after cervical spine fusion.

Ninety of 110 consecutive patients with rheumatoid deformities of the cervical spine surgically treated had associated neurologic deficits. Fifty-five patients had atlantoaxial subluxation. In this group, there were 16 Ranawat Class I patients (normal), 21 Class II (weakness, hyperreflexia, dysesthesia), 13 Class IIIA (paresis and long-tract findings but can ambulate), and five Class IIIB (quadriparesis and inability to ambulate). After C1-C2 stabilization, 94.8% improved at least one class. Twenty-two patients had AAS-SMO (atlanto-axial subluxation and superior migration of the odontoid) only one before surgery was Class I, five Class II, eight Class IIIA, and eight Class IIIB. Seventy-six percent improved at least one class after surgery. Nineteen had isolated subaxial subluxation (SAS). Three were Class I, two Class II, nine Class IIIA, and five were Class IIIB. After surgery, 94% improved at least one class, and all were ambulating. Fourteen had combined AAS-SMO-SAS deformities. There were no Class I patients, only four Class II, four Class IIIA, and six Class IIIB. After surgery, 71% improved. The four deaths that occurred in the immediate postoperative period were Class IIIB. Fifteen patients had worsening or recurrence of their symptoms. Thirteen of these were related to the later development of subaxial subluxation. Neurologic symptoms and recovery were related to severity of the deformity. Those with SMO had greater neurologic deficits and worse results. In general, neurologic recovery is encouraging even in the IIIB patient. Earlier surgery should be done, however, particularly before SMO develops, if possible.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Recurrence of cervical spine instability in rheumatoid arthritis following previous fusion: can disease progression be prevented by early surgery?

In a retrospective study, 110 patients with rheumatoid arthritis who had cervical spine fusion were evaluated for recurrence of cervical spine instability and resultant need for further surgery. Recurrence of cervical instability was correlated with initial radiographic abnormality, primary surgical procedure and interval between the 2 surgeries. There were 55 patients who had atlantoaxial subluxation (AAS) and required C1-C2 fusion as primary surgery. Three of these patients (5.5%) developed subaxial subluxation (SAS) and had a second procedure after a mean interval of 9 years. Twenty-two patients had AAS with superior migration of the odontoid (AAS-SMO) and had initial surgery of occiput-C3 fusion. Eight of these patients (36%) developed SAS and had a second surgery after a mean interval of 2.6 years. Of the 19 patients with primary radiographic deformity of SAS, one required further surgery for subluxation of an adjacent superior vertebra after a period of 6 years. Fourteen patients had combined deformity of AAS-SMO-SAS, and one required further surgery for SAS after an interval of 22 months. Recurrence of cervical instability following a previous fusion occurred in 15% of these 110 patients. It was seen in 5.5% of patients with initial deformity of AAS vs 36% of patients with AAS-SMO. No patients with C1-C2 fusion for AAS progressed to develop superior migration of the odontoid. We conclude that early C1-C2 fusion for AAS before development of SMO decreases the risk of further progression of cervical spine instability. The pattern of progression of cervical spine involvement, as discussed in the literature, is reviewed.

Aged↗
PubMed1992

Dissociation of modular hip arthroplasty components after dislocation. A report of three cases at differing dissociation levels.

Modular hip arthroplasty systems, currently widely employed, offer the advantage of increased intraoperative flexibility in component selection with reduced inventory, as well as the disadvantage of modular component dissociation. Dissociation during closed reduction for dislocation is reported in three patients at three different interface levels: (1) fixed acetabular shell-polyethylene linear interface, (2) bipolar acetabular component-femoral head interface, and (3) femoral head-neck interface. Subsequent open reduction was required in each case. Although this potential disadvantage of modular hip systems does not outweigh the benefits, it does warrant that certain precautions be taken when implanting modular components. The acetabular linear should lie flush within the metallic shell after impaction. The femoral head should be firmly impacted onto the neck. Both should resist reasonable manual force of disassembly. Should a modular hip arthroplasty component dislocate, gentle reduction under general anesthesia and fluoroscopic control is warranted. Careful inspection of pre- and postreduction roentgenograms for signs of modular component dissociation is mandatory.

Adult↗
PubMed1991

Symptomatic gas-containing disc herniation. Report of four cases.

Intradiscal gas collection, causing the radiographic vacuum phenomenon, is a common finding on radiographic studies of the lumbar spine. Four cases of radiographically documented and surgically confirmed cases of herniated discs containing gas are presented. All four patients presented with radicular symptoms secondary to the gas-containing herniations. Minimal nuclear material was found at surgery; however, all patients experienced relief after the operation.

Aged↗
PubMed1991

Incidence of subaxial subluxation in patients with generalized rheumatoid arthritis who have had previous occipital cervical fusions.

A retrospective study of 79 patients with rheumatoid arthritis was undertaken to determine the incidence of subaxial subluxation after upper cervical fusions. Fifty-five patients had isolated axial subluxation and underwent atlantoaxial fusion. Twenty-four underwent occipitocervical fusion for atlantoaxial subluxation and superior migration of the odontoid. The two groups were comparable in age, duration of disease, and time to follow-up (atlantoaxial fusion, 65.4 months; occipitocervical fusion, 72.6 months). Fusion rates were comparable: 80% atlantoaxial fusion and 90.1% occipitocervical fusion. Of the occipitocervical fusion patients, 36% developed subaxial subluxation requiring surgery at an average of 2.6 years after fusion. Of the atlantoaxial fusion patients, 5.5% developed subaxial subluxation requiring surgery after an average of 9 years after fusion. No patient with atlantoaxial fusion developed superior migration of the odontoid. Subaxial subluxation requiring surgery developed early in patients after occipitocervical fusion. This was not true of atlantoaxial fusion. Early atlantoaxial fusion seemed to prevent the development of superior migration of the odontoid. When occipitocervical fusion is necessary and early subaxial subluxation is present, longer fusions or occipitocervicothoracic fusion should be strongly considered.

Adult↗
PubMed1991

Extraspinal causes of lumbosacral radiculopathy.

Twelve of 12,125 patients who had been referred during a seven-year period to a specialist in spinal disorders were found to have an extraspinal cause of radiculopathy or neuropathy of the lower extremity. The records of these twelve patients were reviewed retrospectively. The average age of the twelve patients was sixty-five years (range, forty-two to seventy-seven years). The cause of the symptoms was an occult malignant tumor in nine patients and a hematoma, an aneurysm of the obturator artery, or a neurilemoma of the sciatic nerve in the others. The average time from the onset of symptoms to the final diagnosis was eight months (range, one month to two years). The most useful test for determination of the correct diagnosis was computed tomography or magnetic resonance imaging of the abdomen and pelvis. Computed tomography or magnetic resonance imaging of the spine and bone-scanning of the whole body were of little help in localizing the disease. In four of the twelve patients, an operation was performed on the basis of an incorrect diagnosis. In dealing with elderly patients who have radiculopathy, one should be suspicious that the cause is outside the spine.

Adult↗