摘要:

AbstractCompression of the spinal nerve roots may occur clinically at multiple levels at the same time; however, the basic pathophysiology of multilevel compression is largely unknown. In this study, the intraneural blood flow was analyzed continuously in the uncompressed segment between two compression balloons, with a pig used as an experimental model and a thermal diffusion method. At 10 mm Hg compression, there was a 64% reduction of total blood flow in the uncompressed segment compared with pre‐compression values. Total ischemia occurred at pressures 10‐20 mm Hg below the mean arterial blood pressure. After two‐level compression at 200 mm Hg for 10 min, there was a gradual recovery of the intraneural blood flow towards the baseline. Recovery was less rapid and less complete after 2 h of compression. Double‐level compression of the cauda equina can thus induce impairment of blood flow, not only at the compression sites, but also in the intermediate nerve segments located between two compression sites, even at very low pressures. These findings may have clinical importance in the understanding of the pathophysiology of multiple‐level cauda equina co

ISSN:0736-0266    

DOI:10.1002/jor.1100110112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe evaluated the effects of intraosseously administered prostaglandin E2(PGE2) within the proximal metaphysis of the goat (caprine) tibia under intraosseous normotensive and hypertensive conditions. PGE2was administered at 0.5 or 1.0 mg (1 ml vol) twice daily for 10 days via an Osteoport which had been surgically implanted within the proximal tibial metaphysis. Intraosseous hypertension was produced when venous outflow obstruction (VOO) was created by ligation of the popliteal vein, which drained the proximal tibia, and occlusion of the diaphyseal medullary space distally with bone cement. After VOO, the intraosseous pressure measured at the metaphysis increased significantly (p<0.05) from a baseline mean of 14.9 ± 4.2 mm Hg to 28.6 ± 5.3 mm Hg. Serum radioimmunoassays indicated that VOO prolonged the venous drainage of PGE2from the tibia after an infusion. Static histomorphometric analysis indicated a marked dose‐dependent increase in new bone formation in all PGE2groups at 30 days after the PGE2infusion. Significant (p<0.05) formation of new bone occurred, primarily at the subperiosteal and endocortical surfaces, and moderately increased the marrow cavity of cancellous new bone as compared with the VOO‐only group and the controls. Bone remodeling indices were also increased by PGE2. The PGE2infusion, combined with VOO, produced significantly more new bone formation than the PGE2infusion alone. Intensive marrow fibrosis was associated with the active bone remod

ISSN:0736-0266    

DOI:10.1002/jor.1100110113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe differentiating and antitumor activities of 1α,25‐dihydroxyvitamin D3(1α,25(OH)2D3) in vitro and 1α‐hydroxyvitamin D3(1α(OH)D3) in vivo were studied with a human osteosarcoma cell line (OST strain). Antitumor activity was estimated with the use of 3‐(4,5‐dimethylthiazol)‐2, 5‐diphenyltetrazolium bromide (MTT) assay, colony‐forming assay, and athymic mouse assay. The intracellular alkaline phosphatase (ALP) activity of tumor cells and production of bone Gla protein (BGP) in culture media were measured to mark osteoblastic differentiation. In addition, the combination of 1α,25(OH)2D3and cis‐dichlorodiammineplatinum(II) (CDDP) was tested by the colony‐forming assay and the measurement of ALP activity and BGP production for differentiating and antitumor effects. The assays revealed that 1α,25(OH)2D3exerted a dose‐related, growth‐inhibitory influence. In the colony‐forming assay, the 1α,25(OH)2D3‐treated colonies were smaller than the untreated colonies. The ALP activity and the BGP production also increased in relation to dose. In the assay in athymic mice, the relative weight of tumors treated with 1α(OH)D3at 2.5 nmol/kg was significantly smaller than that of the controls, and no side effects were observed in the 1α(OH)D3‐treated mice. Marked tumor chondrogenesis was observed in human osteosarcoma treated with 1α(OH)D3in athymic mice. The combination of 1α,25(OH)2D3at 10−8Mand CDDP at 2 μg/ml significantly enhanced both the differentiation and the growth inhibition in vitro. Our study apparently is the first demonstration that vitamin D3metabolites have an antitumor and differentiating effect on human osteosarcoma cells in vitro and in athymic mice. Vitamin D3should be examined further to discover whether it could be a useful drug in h

ISSN:0736-0266    

DOI:10.1002/jor.1100110114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe time course of knee extension torque was measured in human quadriceps muscles during 30 min of transcutaneous neuromuscular electrical stimulation (NMES). Ninety subjects were divided into six experimental groups (n = 15 per group), which received stimulation at one of the following frequency/duty cycle combinations: 10 Hz/50%, 30 Hz/50%, 50 Hz/50%, 10 Hz/70%, 30 Hz/70%, and 50 Hz/70%. Two‐way analysis of variance revealed that the magnitude of the relative torque decrease (the percentage of decrease in torque relative to the initial value) was significantly different between frequencies (p<0.005) and duty cycles (p0.6). Increasing either frequency or duty cycle caused a greater decrease in torque. In spite of this result, there was no significant difference between groups in the total activity (torque‐time integral) achieved during the 30 min treatment session. The magnitude of this activity corresponded to only about 7–14 maximum voluntary contractions. Finally, the average torque during the treatment session was significantly different among groups (p<0.001), being greatest for the 50 Hz/50% group and least for the 10 Hz/70% group. Taken together, these data suggest that a smaller number of longer duration contractions produces the greatest muscle tension. They also suggest that the absolute torque levels achieved with NMES are relatively low compared with voluntary muscular act

ISSN:0736-0266    

DOI:10.1002/jor.1100110115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe fixation of cemented and noncemented tibial components in 19 total knee arthroplasties was examined 3 to 10 weeks postoperatively with roentgen stereophotogrammetric analysis. Physiologic external forces were applied either in outward‐inward rotation or as eccentric posterior loading generated by squatting. In one case there was no motion, while in the remaining 18 cases relative interface motion of up to 1 3 mm was found. In some cases, the largest motion was found during inward‐outward rotatory stress, while in others, the largest motion was found during squatting. Posterior tilt was weakly correlated with posterior displacement of the femoral component on the tibia during squatting (r2= 0.323, p<0.05). For the noncemented cases, the initial fixation to bone was probably insufficient, and ingrowth of bone would not have been achieved. For the cemented cases, motion of the implant was reduced. Given the short postoperative time and the probable absence of any substantial fibrous tissue membrane, we suggest that the observed motion represented elastic deformation of the b

ISSN:0736-0266    

DOI:10.1002/jor.1100110116

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study was undertaken to determine how accurately total graft force and load‐sharing between graft segments could be set and maintained during augmented anterior cruciate ligament (ACL) reconstruction in the goat knee. Special procedures were developed to reduce the effect of tissue creep and to overcome difficulties in the setting of graft force. Five knees from goat cadavers were reconstructed using a bone‐tendon‐bone graft (PT) and a synthetic augmentation device (LAD). Prescribed levels of total graft force and load‐sharing between the autograft and LAD were set under a standardized external joint load. Immediately after fixation, the set force declined an average of 9 and 3% in the LAD and PT, respectively. After three subsequent exercise sequences, the set forces fell from their initial level by an average of 25% for the LAD and 28% for the PT. An analysis of variance did not show the loss of force with exercise to be statistically significant. We conclude from this in vitro study that our method can be used to set forces in an ACL reconstruction with reasonable maintenance of load‐sharing but that losses of approximately 30% of total graft force after exercise of the reconstructed joint are to be

ISSN:0736-0266    

DOI:10.1002/jor.1100110117

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0736-0266    

DOI:10.1002/jor.1100110101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY