Biomedical subjects

S D Boden

Publications and source records attributed to S D Boden.

At least 91 records · Page 5Linked to original sources

PubMed1994

Rheumatoid arthritis of the cervical spine. Surgical decision making based on predictors of paralysis and recovery.

OBJECTIVE: This article reviews the current knowledge of predictors of paralysis and the potential for neurologic recovery in patients with rheumatoid arthritis involving the cervical spine. The primary goal is to prevent the onset of an irreversible neurologic deficit. SUMMARY OF BACKGROUND DATA: Use of the posterior atlantodental interval of less than 14 mm as measured from lateral cervical radiographs is a reliable screening tool for identifying high risk patients who require further evaluation with magnetic resonance or computed tomography/myelography. The primary technical objective of surgery in patients with impending neurologic deficit is stabilization of the diseased spine segments and relief of spinal cord compression via reduction of subluxation or direct decompression. Complications are not uncommon, but tend to occur less frequently in patients who have surgical intervention before the onset of severe myelopathy. Pain relief is good when a solid arthrodesis is achieved, and neurologic recovery is most favorable when severe cord compression is not present preoperatively. CONCLUSION: An improved understanding of the natural history, physical findings, and radiographic parameters will allow the construction of a management strategy for timely intervention in rheumatoid patients with progressive cervical disease.

Arthritis, Rheumatoid↗

PubMed1994

Spine update. The use of animal models to study spinal fusion.

The outcome of a spinal fusion depends upon a multifactorial process. Therefore, it is difficult and impractical to study individual variables clinically. Animal models have been useful in studying the parameters that influence the spinal fusion process. Despite the knowledge gained from previous animal studies, there exists a large void in our basic understanding of this complex process. The purpose of this update is to review the concept of animal models of spine fusion by summarizing previous models, identifying strengths and deficiencies, reviewing the strategy for selecting a model, and highlighting knowledge gaps suitable for future research. With recent advances in the knowledge regarding gene-specific therapies and the availability of osteoinductive proteins, we have entered a new era of biologic manipulation of bone formation. Animal data, however, are only as applicable as the model from which it is derived, and future animal models must overcome the deficiencies highlighted in this review. A valid animal model will prove essential in studying the use of growth factors for spinal fusion. The ultimate goal is that fusion nonunions will no longer be of clinical concern.

Animals↗

PubMed1994

Operative treatment of syndesmotic disruptions without use of a syndesmotic screw: a prospective clinical study.

A new protocol for the selected omission of transsyndesmotic fixation in Weber class C ankle fractures was prospectively evaluated in 21 consecutive patients. As proposed in a previous cadaveric study (J. Bone Joint Surg., 71A:1548-1555, 1989), the protocol suggested that transsyndesmotic fixation was not required if (1) rigid bimalleolar fracture fixation was achieved or (2) lateral without medial fixation was obtained (i.e., with accompanying deltoid tears) if the fibular fracture was within 4.5 cm of the joint. According to this protocol, only 3 of 21 patients (14%) required transsyndesmotic fixation. Ten of the patients who did not receive transsyndesmotic fixation underwent pronation-external rotation stress radiographs in a fashion analogous to the previous cadaveric study. At 1- to 3-year follow-up, no stress (N = 10) or static view (N = 18) widening of the mortise or syndesmosis was seen in any patient, which supports (with the above guidelines) a limited, rather than routine, use of supplemental transsyndesmotic fixation. Clinical results from this prospective study seem to substantiate previously proposed biomechanical guidelines for the selected omission of transsyndesmotic fixation. Given these guidelines, transsyndesmotic fixation was unnecessary in many cases and the need can be determined before surgery by assessing the integrity of the deltoid ligament and level of the fibular fracture.

Ankle Injuries↗

PubMed1994

Increased expression of tissue plasminogen activator messenger ribonucleic acid is an immediate response to parathyroid hormone in neonatal rat osteoblasts.

Osteoblasts have been reported to produce tissue-type (t) plasminogen activator (PA), which may be involved in the initiation of bone resorption via plasmin-metalloproteinase degradation of adjacent extracellular matrix. To investigate this cAMP-activated gene, we characterized the PTH regulation of tPA messenger RNA (mRNA) in neonatal rat osteoblast cultures before and after differentiation in vitro. RNA was purified from cultures at confluence or after treatment with glucocorticoid for 1 week and BGJ/ascorbic acid/beta-glycerophosphate for a second week. Northern blots of total or poly(A)+ RNA were hybridized simultaneously with an oligonucleotide or complementary RNA probe for rat tPA and an oligomeric DNA probe for cyclophilin (CYP), an abundant control gene. Differentiation was monitored by expression of rat osteocalcin mRNA and protein. Both bovine PTH1-34 and forskolin caused an increase in tPA/CYP ratio in the presence of phosphodiesterase inhibitor (IBMX) and cycloheximide (CHX). The effect was maximal (16- to 21-fold increase in tPA mRNA and 6- to 8-fold increase in tPA/CYP ratio) with 25 nM hormone for 6 h and was half-maximally stimulated by 0.75-2.5 nM PTH. The tPA response to PTH was present in first passage osteoblast cultures at confluence and after 1 to 2 weeks of glucocorticoid treatment. Exposure of the differentiated cultures of 1,25-dihydroxyvitamin D (10 nM) for 2 days markedly stimulated osteocalcin mRNA while having no effect on tPA. In Northern blots of poly(A)+ RNA from cultures not treated with CHX, IBMX and PTH (2.5 h) independently stimulated tPA mRNA with no significant effect on CYP mRNA levels. The tPA/CYP ratio increased in five consecutive experiments and the effect of IBMX and PTH were additive. These data indicate that PTH acts via cAMP to stimulate tPA expression by a mechanism that is independent of protein synthesis. The enhancement of PTH action by CHX is compatible with feedback inhibition of tPA transcription by a hormone-activated repressor (which has been proposed to occur in granulosa cells) but effects of CHX on tPA mRNA stability may also occur. Expression of tPA mRNA before and after differentiation may indicate that the enzyme has more than one function.

Animals↗

PubMed1994

Increase of motion between lumbar vertebrae after excision of the capsule and cartilage of the facets. A cadaver study.

Seventeen fresh segments of cadaveric lumbar spines were tested in flexion, extension, and axial rotation. The resulting angular rotations were measured with the use of a goniometer and a three-dimensional system of video analysis. Measurements of flexibility were made, in order, in the intact spine; after decompression (bilateral total laminectomies, partial medial facetectomies, and foraminotomies); after excision of the capsule and cartilage of the facets; and after cancellous bone had been packed into the facet defects. Decompression resulted in a slight increase in the sagittal and axial ranges of motion. Subsequent excision of the capsule and cartilage of the facets, as in preparation for an arthrodesis of the facets, resulted in a significant increase in both the sagittal (5.7 +/- 2.9 degrees, mean and standard deviation) (p < 0.001) and the axial (1.4 +/- 0.9 degrees) (p < 0.01) ranges of motion compared with the motion in the intact specimen and with the motion in the specimen after only decompression had been done (p < 0.01 and p < 0.05, respectively). Packing of bone in the facets did not significantly reduce motion. It was calculated that the increase in the sagittal range of motion after excision of the capsule and cartilage of the facets would increase the tensile strain in a graft between the transverse processes of the fourth and fifth lumbar vertebrae (18 +/- 1 per cent tensile strain [mean and 95 per cent confidence interval] for the intact vertebrae and 25 +/- 1 per cent for the vertebrae in which the facets had been excised).

Biomechanical Phenomena↗

PubMed1994

A quality-based protocol for management of musculoskeletal injuries. A ten-year prospective outcome study.

Musculoskeletal injuries in the workplace are recognized as a major health and economic problem; however, little has been done to develop strategies that emphasize both quality and cost control. The purpose of this ten-year perspective investigation was to evaluate the use of quality-based standardized diagnostic and treatment protocols as part of an unbiased injury surveillance system. The program was evaluated in a public utility company with more than 5300 employees, and resulted in a measurable and long-term improvement in all outcome parameters measured: (1) The number of days lost from work and the number of new injuries reported fell by 55 and 51%, respectively. (2) The average time lost per injury dropped by 40%. (3) The number of surgeries performed decreased by 67%, and the operative success rate increased dramatically. (4) Finally, as an added benefit, there was a 60% reduction in expenditures for lost time and replacement wages, resulting in a cumulative ten-year savings of more than 4.1 million dollars. The program accomplished the goal of ensuring quality care in a prospective concurrent fashion. As an additional benefit, the program also reduced unjustified lost time and compensation costs through early functional return, efficient use of diagnostic studies, and avoidance of surgery whenever possible. Future emphasis on health-care delivery in the workers' compensation setting should concentrate on high-quality medical care, which will, in turn, lead to secondary cost savings.

Algorithms↗

PubMed1993

Rheumatoid arthritis of the cervical spine. A long-term analysis with predictors of paralysis and recovery.

We analyzed the cases of seventy-three patients who were managed over a twenty-year period for rheumatoid involvement of the cervical spine and were followed for a minimum of two years, with an average follow-up of seven years. A neurological deficit did not develop in thirty-one patients (Ranawat et al. Class I) and paralysis developed in the remaining forty-two patients: Class II in eleven and Class III in thirty-one. Of the forty-two patients in whom paralysis developed, thirty-five had operative stabilization. Seven patients were managed with a soft cervical collar because they refused or were medically unable to have the operation; all of the had an increase in the severity of the paralysis. The posterior atlanto-odontoid interval and the diameter of the subaxial sagittal canal measured on the cervical radiographs demonstrated statistically significant correlations with the presence and severity of paralysis. All of the patients who had a Class-III neurological deficit had a posterior atlanto-odontoid interval or diameter of the subaxial canal that was less than fourteen millimeters. In contrast, the anterior atlanto-odontoid interval, which has traditionally been reported, did not correlate with paralysis. The prognosis for neurological recovery following the operation was not affected by the duration of the paralysis but was influenced by the severity of the paralysis at the time of the operation. The most important predictor of the potential for neurological recovery after the operation was the preoperative posterior atlanto-odontoid interval. In patients who had paralysis due to atlanto-axial subluxation, no recovery occurred if the posterior atlanto-odontoid interval was less than ten millimeters, whereas recovery of at least one neurological class always occurred when the posterior atlanto-odontoid interval was at least ten millimeters. If basilar invagination was superimposed, clinically important neurological recovery occurred only when the posterior atlanto-odontoid interval was at least thirteen millimeters. All patients who had paralysis and a posterior atlanto-odontoid interval or diameter of the subaxial canal of fourteen millimeters had complete motor recovery after the operation. In this series, although only patients who had a neurological deficit were operated on, we observed the range of the posterior atlanto-odontoid interval that was associated with poor or no recovery after the operation, and we identified the safe range on the basis of the patients in whom paralysis did not develop.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

Impairment evaluation based on spinal range of motion in normal subjects.

Spinal range of motion is a major determinant of impairment in many disability rating schedules used today. The validity of using spinal motion as the primary variable for impairment ratings must be questioned because of the large spectrum of age-related changes in motion in a normal population. The purpose of this investigation was to test the validity of this concept by determining spinal impairment in normal subjects using one of the more popular rating systems, the American Medical Association (AMA) Guides to the Evaluation of Permanent Impairment. Ninety-five individual measurements of cervical and lumbar spine motion were performed on each of 81 healthy subjects by two examiners using the double-inclinometer method. Based on the AMA criteria, all of the normal subjects were noted to have some degree of impairment ranging from 2 to 38.5%, with a mean value of 10.8%. The level of impairment increased with age for cervical, lumbar, and total impairment percentages (p = 0.0001). The current method of impairment determination based on spinal motion may not accurately reflect impairment in many patients. Impairment may be overestimated by up to 38%. Alternate methods of impairment evaluation should be developed that are more specific for individuals with true functional impairment and that account for age-related differences in spinal motion.

Adult↗

PubMed1992

Contrast-enhanced MR imaging performed after successful lumbar disk surgery: prospective study.

A prospective study was undertaken to establish the normal spectrum and timing of gadolinium-enhanced magnetic resonance (MR) imaging findings in 15 patients who had resolution of symptoms after successful lumbar disk surgery. Enhancement of the facet joints (in 88% of disk levels) and paraspinal muscles (100%) decreased gradually after surgery. Enhancement of the decompressed nerve root tracked proximally toward the conus medullaris in 62% at 3 weeks and was absent in all by 6 months postoperatively. Areas of intermediate signal intensity with peripheral enhancement and mass effect were seen on T1-weighted images at the site of the original disk herniation in 38% at 3 weeks and 12% at 3 months, despite complete relief of leg pain. These results reveal that even in successfully treated (asymptomatic) patients, residual mass effect on the neural elements may frequently simulate a recurrent or residual disk fragment. There is an orderly progression of imaging changes during the first 6 months after lumbar surgery that limits the interpretation of MR examinations during that period.

Adult↗

PubMed1992

Postoperative diskitis: distinguishing early MR imaging findings from normal postoperative disk space changes.

To distinguish early magnetic resonance (MR) imaging findings in postoperative diskitis from normal postoperative changes, a prospective study was performed in 15 asymptomatic patients (17 disk levels) who underwent uncomplicated lumbar diskectomy and seven patients with proved postoperative diskitis. On postoperative MR images, four of the asymptomatic patients had a finding that could also be seen in patients with diskitis. Gadolinium enhancement was useful in making the distinction and occurred as follows: (a) vertebral bone marrow: all seven diskitis patients and one asymptomatic patient; (b) disk space: five diskitis patients and three asymptomatic patients; and (c) posterior anulus fibrosus: all seven diskitis patients and 13 asymptomatic patients (14 of 17 levels). This entire triad of findings, which is strongly suggestive of postoperative diskitis, was not seen in any of the asymptomatic patients. Changes in the disk space and adjacent bone marrow on pre- and post-contrast MR images after routine diskectomy are uncommon and should not be assumed to be normal postoperative changes without careful consideration and analysis for early diskitis.

Adult↗

PubMed1992

Hematopoietic bone marrow hyperplasia: high prevalence on MR images of the knee in asymptomatic marathon runners.

In a prior study of marathon runners, we noticed that MR scans of the knee frequently showed hyperplasia of red (i.e., hematopoietic) bone marrow. Because the frequency of this finding in various populations is unknown, the purpose of this study was to determine the relative prevalences of hematopoietic bone marrow hyperplasia on MR examinations of the knees of healthy volunteers (n = 74), patients with symptoms of knee disorders (n = 54), and asymptomatic marathon runners (n = 23). The prevalence of hematopoietic bone marrow hyperplasia was 3% (2/74) for the healthy volunteers, 15% (8/54) for the patients, and 43% (10/23) for the marathon runners. The difference in prevalence between each of the three groups was statistically significant at p less than .05 in each case with hematopoietic bone marrow hyperplasia, the distal femur was the only area affected, while the epiphysis and proximal tibia were uninvolved. This pattern of affected bone marrow with hyperplasia of the hematopoietic marrow may be useful for the differential diagnosis. We postulate that the high prevalence of hematopoietic bone marrow hyperplasia in marathon runners may develop as a response to "sports anemia", which is commonly found in highly conditioned, aerobically trained athletes. Furthermore, this is considered to be a normal variant when found in the pattern described here.

Bone Marrow↗

PubMed1992

A prospective and blinded investigation of magnetic resonance imaging of the knee. Abnormal findings in asymptomatic subjects.

To evaluate magnetic resonance imaging (MRI) of meniscal, ligamentous, and bony abnormalities in patients without clinical symptoms, scans were performed on 74 asymptomatic volunteers without histories or symptoms of knee injury. Before review by three radiologists in an independent and blinded fashion, the scans were mixed with 26 MRI scans from symptomatic patients. Sixteen percent of the asymptomatic volunteers had meniscal abnormalities consistent with a tear. The prevalence of MRI findings of a meniscal tear increased from 13% in individuals younger than 45 years of age to 36% in those older than 45. An additional 30% of the volunteers showed meniscal abnormalities consisting of a linear area of increased MR signal not communicating with a meniscal edge, which was not interpreted to represent a tear. The high incidence of abnormal MRI findings in asymptomatic subjects underscores the danger of relying on a diagnostic test without careful correlation with clinical signs and symptoms. These findings also emphasize the importance of access to relevant clinical data when interpreting MRI scans of the knee.

Adolescent↗

PubMed1992

Estrogen receptors in fracture healing.

Estrogen has profound effects on the regulation of bone metabolism, but its role in fracture healing is unknown. Several recent reports have documented the presence of estrogen receptors in vitro and in diseased tissue. The authors investigated estrogen receptors in nonneoplastic skeletal tissues by immunohistochemical and radioligand binding techniques. Using a fibular osteotomy model of fracture healing in New Zealand rabbits, radioligand binding detected specific, high affinity, saturable estradiol binding sites at low levels throughout fracture healing, with a trend towards a bimodal distribution. Peaks occurred three and 16 days after osteotomy. No estrogen receptor was found by either method in later fracture callus, growth plate, or periosteum. These findings suggest a possible role for estrogen in the early inductive phase and later phase of endochondral ossification in fracture healing.

Animals↗

PubMed1990

Hip fractures in young patients: is this early osteoporosis?

Hip fracture in patients under age 50 is rare, and is often not attributable solely to the energy of injury. Our aim was to determine if trabecular bone mineral density (BMD) is abnormal in young patients with hip fractures. We reviewed all hip fractures treated at our institution between 1979 and 1986 and contacted 20 patients under the age of 50 at the time of injury, all of whom wished to be studied. The mean age at the time of injury was 39 (range 24-47). Subjects were questioned for osteoporosis risk factors, classified by level of energy producing their injury, and then underwent quantitative computed tomography (QCT) bone densitometry of trabecular bone in the lumbar spine. Bone mineral density by QCT was below the mean for age in 90% of the patients, and was greater than 1 SD below the mean in 75%. Mean percentage BMD decrease from age-matched controls was 34% (P less than 0.005) in women and 19% (P less than 0.005) in men. There was an inverse correlation in the degree of BMD decrease and the energy level of injury. There was a direct correlation of the severity of BMD decrease and the cumulative number of osteoporosis risk factors. This investigation has found that 1-7 years following hip fracture, otherwise presumedly healthy young patients demonstrate a statistically significant decrease in spinal BMD from age/sex-matched controls. These data do not determine if osteopenia is the cause or the result of injury, nor do we wish to infer that measurement of bone density at one site can predict future fractures at other sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

MR scanning of the acutely injured knee: sensitive, but is it cost effective?

Although magnetic resonance (MR) imaging has been established as an accurate diagnostic modality for knee pathology, the cost-effectiveness of this test is not known. In this investigation, we formulated a mathematical equation to assess cost-effectiveness and then used this formula to evaluate the use of knee MR as a diagnostic modality in acute knee injuries. We analyzed 105 consecutive MR scans performed at an imaging center with a diverse referral base, and identified 63 patients who had had symptoms for less than 6 months. Based on average regional medical costs, we calculated that diagnostic arthroscopy is more cost-effective than MR if 78% of the scanned patients eventually undergo arthroscopy. In our study population, 87% had arthroscopy after the MR scan. Therefore, in this patient cohort representing a diverse orthopedic community, arthroscopy alone would have been more cost-effective. Careful analysis in this type of cost-benefit framework would be beneficial and may lead to the establishment of objective criteria by which MR can be used in the most cost-effective manner.

Adult↗

PubMed1990

Lumbosacral segmental motion in normal individuals. Have we been measuring instability properly?

The utility or futility of flexion-extension radiographs in the diagnosis of lumbar spine segmental instability is a controversial issue. Previous investigations have reported a large range of normal motion and a significant overlap of symptomatic and asymptomatic motion patterns. The authors' goal was to define normal lumbosacral motion in vivo using ordinary weight-bearing lateral flexion-extension radiographs from 40 volunteers without the use of computers or special X-ray equipment. Calculation of dynamic vertebral translation, defined as the change in relative position from flexion to extension, provided a more accurate assessment of vertebral motion than measurement of static displacement on a flexion or extension view alone. Normal lumbar vertebral levels should have less than 3.0 mm of dynamic anteroposterior (AP) translation (less than 8% of vertebral body width). Although 42% of the normal subjects had at least one level with a static olisthesis greater than 3.0 mm in either flexion or extension, only 5% had a dynamic AP translation greater than 3.0 mm. These data have suggested that the previously reported large range of motion and frequency of overlap between symptomatic and asymptomatic patients may be significantly decreased (eightfold) by calculating dynamic motion, rather than static vertebral positions. The authors believe these data will provide the basis for reassessment of flexion-extension radiography in the diagnosis of lumbar spine instability.

Adult↗

PubMed1990

Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation.

We performed magnetic resonance imaging on sixty-seven individuals who had never had low-back pain, sciatica, or neurogenic claudication. The scans were interpreted independently by three neuro-radiologists who had no knowledge about the presence or absence of clinical symptoms in the subjects. About one-third of the subjects were found to have a substantial abnormality. Of those who were less than sixty years old, 20 per cent had a herniated nucleus pulposus and one had spinal stenosis. In the group that was sixty years old or older, the findings were abnormal on about 57 per cent of the scans: 36 per cent of the subjects had a herniated nucleus pulposus and 21 per cent had spinal stenosis. There was degeneration or bulging of a disc at at least one lumbar level in 35 per cent of the subjects between twenty and thirty-nine years old and in all but one of the sixty to eighty-year-old subjects. In view of these findings in asymptomatic subjects, we concluded that abnormalities on magnetic resonance images must be strictly correlated with age and any clinical signs and symptoms before operative treatment is contemplated.

Adult↗

PubMed1990

Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects. A prospective investigation.

Previous investigations with plain radiography, myelography, and computed tomography have shown that degenerative disease of the cervical spine frequently occurs in the absence of clinical symptoms. We studied the magnetic resonance-imaging scans of sixty-three volunteers who had no history of symptoms indicative of cervical disease. The scans were mixed randomly with thirty-seven scans of patients who had a symptomatic lesion of the cervical spine, and all of the scans were interpreted independently by three neuroradiologists. The scans were interpreted as demonstrating an abnormality in 19 per cent of the asymptomatic subjects: 14 per cent of those who were less than forty years old and 28 per cent of those who were older than forty. Of the subjects who were less than forty, 10 per cent had a herniated nucleus pulposus and 4 per cent had foraminal stenosis. Of the subjects who were older than forty, 5 per cent had a herniated nucleus pulposus; 3 per cent, bulging of the disc; and 20 per cent, foraminal stenosis. Narrowing of a disc space, degeneration of a disc, spurs, or compression of the cord were also recorded. The disc was degenerated or narrowed at one level or more in 25 per cent of the subjects who were less than forty years old and in almost 60 per cent of those who were older than forty. The prevalence of abnormal magnetic-resonance images of the cervical spine as related to age in asymptomatic individuals emphasizes the dangers of predicating operative decisions on diagnostic tests without precisely matching those findings with clinical signs and symptoms.

Adult↗