ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Objective functional capacity measurement techniques were used to guide a treatment program for a group of 66 chronic back pain patients. These patients were compared with a group of 38 chronic patients who were not administered the treatment program. Outcome data were collected by telephone survey at an average 1 year follow-up. In addition, functional capacity measures were collected for treatment group patients on admission and follow-up evaluations. Results demonstrated that the functional capacity measures collected for the treatment group improved in approximately 80% of the patients. These changes were also accompanied by positive changes in psychologic measures. In addition, at 1 year follow-up, the treatment group had approximately twice the rate of patients who returned to work, relative to the comparison group. Additional surgery rates were comparable for both groups (6% in the treatment and 7% in the comparison group), but the frequency of additional health-care professional visits was substantially higher in the comparison group. The findings suggest that quantitative functional capacity measures can give objective evidence of patient physical abilities and degree of effort and can significantly guide the clinician in administering an effective treatment program

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Finite element models (FEMs) and analytical and experimental models based on poroelastic constitutive laws were developed for rhesus spinal motion segments (SMSs). Long-time creep, transient creep, and impact were studied for SMSs with normal and simulated degenerated discs. The results suggested that long-time creep observed in excised SMSs may be reduced in thein vivoSMS. The fluid phase included in these FEMs was shown to play a significant role in the mechanical response of SMSs. Relative fluid motion fields predicted In the SMS could be related to nutritional paths to the avascular interior of the disc and were found to be very sensitive to changes in discal stiffness. Reduced disc height, increased discal bulge, altered fluid motion, and stresses were quantified and may be related to mechanical failure, disc degeneration, and low-back pain.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The observations made in this study strongly support the concept that spinal nerve roots in general and the human lumbosacral spinal nerve roots in particular are structurally, vascularly, and metabolically unique regions of the nervous system. Peculiarities of their intrinsic vasculature and supporting connective tissue may account for suspected “neuroischemic” responses to pathologic mechanical stresses and inflammatory conditions associated with degenerative disease of the lower spine. It is hoped that the newly described features of the radicular vasa nervorum (to avoid confusion with the dissimilar blood supply of peripheral nerves, the term “vasa radiculorum” might be more accurate) may advance the understanding of certain aspects of lower spine symptomatology and provide some basis for much needed future research.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The forces induced in the disc and ligaments of a lumbar motion segment in resisting a quasi-static external load, using a semi-experimental approach, are presented. The lines of action of ligaments (direction cosines) and disc center for the initial position of the specimen were determined using a morphometer. The changes in these lines of action for a known external load were computed by using the three-dimensional load-deformation characteristics of an intact motion segment. The load-deformation behavior were obtained by applying a known load to the motion segment’s superior vertebra and recording the motion produced. A seven dial gauge motion measuring system was used for this purpose. The six equations of equilibrium yielded a statically indeterminate model. A linear optimization technique in conjunction with a cost function enabled the computation of forces in the ligaments as well as forces and moments in the disc. This approach made it possible to determine the component forces without aprioriknowledge of the structural properties of ligaments. Typically for an external flexion moment of 6.9 Nm the supraspinous ligament experienced the most force (60 N), followed by capsular ligaments (25 N), and transverse ligaments (15 N). A compressive force of 100 N within the disc was predicted. The load-deformation curve, obtained from this study, for the supraspinous ligament was nonlinear and is in agreement with published experimental results.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Fifty-two cadaveric lumbar motion segments were subjected to fatigue loading in compression and bending to determine if the intervertebral discs could prolapse in a gradual manner. Prior to testing, the nucleus pulposus of each disc was stained with a small quantity of blue dye and radiopaque solution. This enabled the progress of any gradual prolapse to be monitored by direct observation and by discogram. Six discs developed a gradual prolapse during the testing period. The injury starts with the lamellae of the annulus being distorted to form radial fissures and then nuclear pulp is extruded from the disc and leaks into the spinal canal. Discs most commonly affected were from the lower lumbar spine of young cadavers. Tests on ten older discs with pre-existing ruptures showed that such discs are stable and do not leak nuclear pulp.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Because the etiology of spondylolysis is not well understood, the authors performed an analysis of loads and stresses in human lumbar vertebrae to determine whether purely mechanical factors are likely to cause spondylolytic fractures in a normal spine. To perform these studies; modeling methods were applied. A mechanical system was developed to study muscle forces and reactions in joints of the lumbar spine. Next an optimization approach was applied to find loads on vertebrae and muscle forces. Finally photoelastic experiments were performed to find effective stresses and stress concentrations in low lumbar vertebrae. The analysis showed that the highest stresses appear in parts interarticularis. The results prove that factors of a purely mechanical nature are of fundamental importance in the etiology of spondylolysis.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The biomechanical effects of discectomy on the motion behavior of whole lumbar spine are investigated using a Selspot II system. Fresh human ligamentous specimens were potted at the sacrum and clinically relevant loads (flexion/extension, right/left lateral bending, and right/left axial torsion moments) applied through a loading frame attached rigidly to the topmost vertebra of the specimen. The resulting three-dimensional motions of each vertebra for the intact specimen were recorded. The specimen was injured sequentially on the right side of the L4-5 level: partial laminectomy, partial facetectomy, subtotal discectomy, and total discectomy. The motion behavior of the specimen after each injury was recorded. The results of the injured tests were normalized with respect to the corresponding intact results. The normalized data for eight specimens were pooled for statistical analysis. Subtotal discectomy induced significantly less motion at the injury site than total discectomy, in all loading modes. At L3-4, the motion segment above the injury level, anteroposterior translation in flexion and lateral translation in left lateral bending show significant increases irrespective of the amount of nucleus excised. The clinical relevance of these findings are discussed.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

One hundred and twenty-two lumbar intervertebral discs from 43 mongrel dogs were used to study the effect of chemonucleolysis on the flexion, torsion, and lateral bending flexibilities of the disc. The dogs were killed 2, 4, 12, 26, and 52 weeks following injection with 0.1-0.15 ml of either crude collagenase, semipurified collagenase, or chymopapain. Controls consisted of saline-injected and uninjected discs. The bending and torsional properties of each disc were determined by applying incremental moments up to 0.8 Nm and measuring the resultant rotations 60 seconds after each load increment was applied. The discs were then sectioned for morphologic evaluation. Increases in disc flexibilities ranging from 1.4 to 5.8-fold were found 2 weeks after injection with all three enzymes. The largest increase was noted in flexion in discs injected with chymopapain. By 3 months, all lateral bending flexibilities had returned to control values. In general, however, flexion and torsion flexibilities did not return to control values 6 months following chemonucleolysis. The extent of the gross morphologic changes produced by each of the three enzyme preparations did not correlate with the acute increases in disc flexibilities. Chymopapain and semipurified collagenase had similar morphologic and mechanical effects. The temporary increases in flexibility appeared to be due to decreases in the overall compression, tensile and shear stiffness of the annulus caused by the enzymes.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Intradiscal injection of proteolytic enzymes implies a potential risk for exposure of nervous tissue to the enzyme solution. In the present study, the effects on peripheral nerve tissue of application of a solution containing a clinically recommended concentration of collagenase have been evaluated. Acute experiments showed that the enzyme induces transient swelling at the site of application and edema in the epineurium. There were, however, no detectable effects on the permeability of the perineurium or the endoneurial microvascular bed. Four and 8 weeks later, there was a slight fibrosis in the epineurium, but neurophysiologic tests did not reveal any impairment of the nerve function. The results are discussed in terms of the clinical use of collagenase for dissolution of herniated intervertebral discs.

ISSN:0362-2436    

出版商:OVID    

年代:1985

数据来源: OVID