Slip Reduction Research Articles

Spondylolisthesis with postural slip reduction shows different motion patterns with video-fluoroscopic analysis

To compare the motion of lumbar spondylolisthesis between the standing and decubitus positions and to identify the radiological parameters concerning segmental instability, the lumbar sagittal motion of 5 volunteers and 14 patients was recorded using video-fluoroscopy in both positions. Still images at three frames per second were captured, and the motion pattern was compared between the two positions. Patients were classified into two subgroups according to the degree of postural slip reduction. In the volunteer group, the motion patterns were not particularly different between the two positions. In the small postural reduction group, the motion patterns were not particularly different between the two positions, except in one patient for whom the range of motion (ROM) at the upper adjacent level increased in the decubitus position. In the large postural reduction group, a motion pattern change was observed. The ROM at the slip level in three patients increased, and in the remaining four patients the angle at the midpoint in ROM at the slip level shifted to the extension side in the decubitus position. This condition (anterior slip being reduced in the supine position, with disc angle and average disc height increased) is thought to result from anterior column deficiency and the vertical laxity of the surrounding soft tissues. A biomechanically stable fusion technique is recommended for surgical management.

P18. Effects of operative positioning on sagittal alignment and slip reduction in isthmic spondylolytic patients

BACKGROUND CONTEXT: Correct sagittal balancing of the spine is important for appropriate load distribution during gait. Slip reduction and prevention of flatback syndrome are desirable outcomes that can be achieved intraoperatively with surgical techniques and instrumentation. However, the operative table may affect the degree to which either can be chieved.

Catalytic combustion of methane in non-permselective membrane reactors with separate reactant feeds

Catalytic combustion of methane over Pd and Pt/SiO 2/α-Al 2O 3 membranes was studied in the temperature range 300–650 °C. Fuel and oxygen were fed at opposite membrane sides. In order to improve reactor controllability the α-Al 2O 3 membranes were impregnated with SiO 2 sol resulting to smaller pore size. Methane conversions up to 100% for the palladium membrane and up to 42% for the platinum membrane were achieved. The results indicated a transition from kinetic to mass transfer control within the temperature range investigated. This was accompanied by reduction of methane slip from tube to shell side with increasing temperature. CO and H 2 were detected in the product gases of the palladium membrane. Their concentration could be reduced by applying a trans-membrane pressure difference. Low concentrations of CO were observed for the Pt/SiO 2/α-Al 2O 3 membrane, while no CO or H 2 were detected for a Pd/α-Al 2O 3 membrane operating in dead-end configuration.

Techniques for repair of gastric prolapse after laparoscopic gastric banding.

Laparoscopic gastric banding is a valuable surgical option for treating morbidly obese patients. Its operative technique is continually being refined. Since its inception, many changes in technique have helped to reduce the complication rate. Currently, the major complications are obstruction, erosion, and band slippage. Band slippage requires surgical correction. Since each band costs approximately 3000 dollars, surgeons should attempt to preserve the band when facing patients with this complication. This paper discusses the techniques for the reduction of band slippage.

The Changes of Sagittal Alignment after Anterior Interbody Fusion with Posterior Fixation in Spondylolisthesis of the Lumbar Spine

Study Design: A prospective radiological assessment was conducted. Objectives: To analyze the changes in the height of the intervertebral disc, the slippage, slip angle, lumbar lordotic angle and sacral inclination after anterior lumbar interbody fusion and posterior pedicle screw fixation in a lumbar spondylolisthesis. Summary of Literature Review: The anterior lumbar interbody fusion causes changes in the lumbar sagittal alignment. Methods: The mini-open anterior lumbar interbody fusion and pedicle screw fixation was undertaken in 33 cases from April 1995 to November 2003. MRI was done before and 6 months after surgery. The measuring factors were the heights of the intervertebral disc, slippage, slip angle, lumbar lordotic angle and sacral inclination. The measuring factors were independently assessed three times by three different orthopedic surgeons. The postoperative changes in measuring the factors were analyzed by a paired t-test statistically. Results: The height of the intervertebral disc was increased by a mean of 14.0%, slippage was reduced by a mean of 2.8%, the slip angle was reduced by a mean of 16.0%, the lumbar lordotic angle was increased by a mean of 15.6% and the scaral inclination was increased by a mean of 3.0%. There was significance in the increase in the disc height, the reduction of slippage and the slip angle, and the increase in lumbar lordotic angle, but there were no significance regarding the changes in sacral inclination. C o n c l u s i o n s: The anterior lumbar interbody fusion and the pedicle screw fixation significantly improved the height of the intervertebral disc, slippage, slip angle, and lumbar lordotic angle, except sacral inclination.

Comparison between Posterior Lumbar Interbody Fusion with Pedicle Screw Fixation and Posterolateral Fusion with Pedicle Screw Fixation in Spondylolytic Spondylolisthesis in Adults

‐ Abstract ‐ Study design: This was a retrospective study that analyzed and compared the results between a posterior lumbar interbody fusion, and a posterolateral fusion (PLIF+PLF), and PLF alone, in the treatment of spondyolytic spondylolisthesis in adults. O b j e c t i v e s: To evaluate the outcomes of two surgical treatment methods for spondylolytic spondylolisthesis-posterolateral fusion alone, and circumferential fusion, using posterior lumbar interbody fusion and posterolateral fusion. Summary of Literature Review: There have been many reports regarding the surgical treatment of spondylolisthesis. Posterior lumbar interbody fusions have certain distinct mechanical advantages over posterolateral ones. However, the clinical and radiological results do not usually correlate. Materials and Methods: Between January 1998 and December 2001, 38 patients, with spondylolytic spondylolisthesis, were operated on by a single surgeon. Nineteen patients underwent a posterolateral fusion alone (group I), with the same number undergoing an additional posterior lumbar interbody fusion (group II). These two groups were evaluated for their clinical outcomes, radiological measurements and fusion rates. Results: The losses in the slip reduction were 7.1 and 1.3% in the PLF and PLF+PLIF groups, respectively (P 0.05). Conclusions: Although the addition of a posterior lumbar interbody fusion, to an instrumented posterolateral fusion, following decompression, is more predictable in maintaining a correction and achieving union, a posterolateral fusion may have a better clinical outcome in patients with low grade spondylolytic spondylolisthesis. Therefore, careful patient selection is necessary for each operation.

Posterior reduction and anterior lumbar interbody fusion in symptomatic low-grade adult isthmic spondylolisthesis: short-term radiological and functional outcome.

The aim of this study was to evaluate the short-term radiological and functional outcome of surgical treatment for symptomatic, low-grade, adult isthmic spondylolisthesis. Twelve patients underwent a monosegmental fusion for symptomatic spondylolisthesis. Posterior reduction with pedicle screw instrumentation was followed by second-stage anterior interbody fusion with a cage. All patients underwent a decompressive laminectomy. At an average of 2.1 (range 1.4-3.0) years following surgery, all patients completed the Oswestry questionnaire, VAS back pain score and a questionnaire detailing their work status. Radiographs were evaluated for maintenance of reduction and fusion. The patients (nine male, three female; mean age 42, range 22-54 years) had experienced preoperative symptoms for an average of 38 (range 6-96) months. An average preoperative slip of 21% (range 11-36%) was reduced to 7% (range 0-17%). Reduction of slip was maintained at latest follow-up, at which time the average VAS score was 2.8 (range 0-8) and the average Oswestry score was 13 (range 0-32). All patients achieved a successful fusion. There were no postoperative nerve root deficits. All patients stated that they would be prepared to undergo the same procedure again if required. Seventy-five percent returned to their pre-symptom work status. Our findings suggest that posterior reduction and anterior fusion for low-grade adult isthmic spondylolisthesis may yield good functional short-term results. A high fusion rate and maintenance of reduction with a low complication rate may be expected. Further follow-up is necessary to evaluate long-term outcome.

Percutaneous pedicle screw fixation as an augmenter of minimally invasive anterior lumbar interbody fusion: preliminary report

Won Kyu Choi, Sang Ho Lee, Seoul, South KoreaIntroduction: Spondylolytic spondylolisthesis and multiple degenerative spondylolisthesis are common lumbar spinal disorders, which display symptoms characteristic of both spinal instability and stenosis. There may be several surgical options considered, such as anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), posterolateral fusion with pedicle screw fixation (PF), PLIF and PF. PLIF and PF are generally considered to provide the highest level of stability, as well as decompression. However, the procedures require wide dissection of normal tissue and excessive neural retraction, which cause increased blood loss, intraspinal neural injury and fibrosis, increased postoperative pain and recovery time. We report on the usefulness of the percutaneous PF (PPF) in augmenting the minimally invasive ALIF (mini-ALIF) for spondylolytic spondylolisthesis and multiple degenerative spondylolisthesis.Methods: We treated 20 symptomatic patients with mini-ALIF and PPF within a relatively short time span. Seventeen patients received one-level lesions, two patients received two-level lesions and one patient three-level lesions, which were confirmed radiologically by plain X-ray, computed tomography (CT) and magnetic resonance imaging.Results: Plain postoperative X-rays and CT scan were taken for all patients to analyze and determine the placement of pedicle screws and the degree of reduction of spondylolisthesis. Most preoperative spondylolisthesis was corrected in all cases. In two cases, the lateral cortical walls of the vertebral body were broken by the screws during slippage reduction and were intraoperatively repaired with bone cement, and screws were re-inserted with some adjustments, making a sound purchase. One screw violation of the inferior pedicle wall in an osteoporotic patient, which was noted intraoperatively, was left because of the possibility of the screw loosening. All but three patients could get out of bed with a brace soon after the operation. The three patients had multiple lesions. Preoperative leg symptoms were reduced considerably immediately after the operation, although surgical back pain persisted for a much longer period of time. One patient had considerable postoperative knee pain, believed to be caused by excessive reduction of L4–5 grade 2 spondylolisthesis. The knee pain gradually diminished over a period of 1 month. Besides the postoperative complications, there were pains in the iliac bone graft site in all cases.Conclusion: Spondylolytic spondylolisthesis and multiple degenerative spondylolisthesis can be treated with mini-ALIF and PPF without using a posterior neural decompressive procedure. PPF not only has the advantages of minimally invasive surgery, but also is not inferior to open conventional screw fixation in terms of accuracy of the screw placement, reduction of slippage and manageability of intraoperative complications, such as cortical bone breakage.

Lumbar sagittal balance influences the clinical outcome after decompression and posterolateral spinal fusion for degenerative lumbar spondylolisthesis.

This study was designed to assess both lumbar sagittal balance and clinical outcomes of decompression and posterolateral fusion for degenerative lumbar spondylolisthesis. As an index for the radiologic evaluation of sagittal alignment, the L1 axis S1 distance was used (i.e., the horizontal distance from the plumbline of the center in the L1 to the back corner of the S1). To determine whether lumbar sagittal balance affected the clinical outcome after posterolateral fusion. Little is known about whether the sagittal vertical axis influences clinical outcomes in cases of degenerative lumbar spondylolisthesis. A retrospective review of 47 patients (15 men and 32 women), ranging in age from 41 to 79 years, was conducted. The mean follow-up period was 3.6 years. Relations among outcomes including the visual analog pain scale, recovery rate, L1 axis S1 distance, slippage, and lumbar lordosis were evaluated. Recovery rates were 44% and 62% in patients whose preoperative L1 axis S1 distance, respectively, was more than 35 mm (Group A, n = 16) and less than 35 mm (Group B, n = 31) (P < 0.05). Follow-up assessment found a positive correlation between only lordosis and recovery rate. Severe low back pain and lower recovery rate were observed in patients with in situ fusion in Group A (n = 9), as compared with patients with reduced slippage in Group A (n = 7) and patients in Group B. Both preoperative L1 axis S1 distance and lordosis at follow-up assessment affected surgical outcome. Reduction of slippage may improve clinical outcomes of posterolateral fusion for degenerative lumbar spondylolisthesis with an L1 axis S1 distance more than 35 mm.

The timing of reduction and stabilisation of the acute, unstable, slipped upper femoral epiphysis.

We reviewed the management of 100 cases of slipped upper femoral epiphysis treated over a period of 26 years. A total of 14 slips was identified as unstable on admission. These underwent reduction and stabilisation within 24 hours of the onset of severe symptoms. Of the 86 stable slips four progressed to avascular necrosis (AVN), which was not seen in the unstable slips. The literature on slipped upper femoral epiphysis suggests that the acute unstable slip is at higher risk of developing AVN. We recommend reduction and stabilisation of unstable slips within 24 hours of the onset of symptoms in order to reduce the risk of AVN.

The timing of reduction and stabilisation of the acute, unstable, slipped upper femoral epiphysis

We reviewed the management of 100 cases of slipped upper femoral epiphysis treated over a period of 26 years. A total of 14 slips was identified as unstable on admission. These underwent reduction and stabilisation within 24 hours of the onset of severe symptoms. Of the 86 stable slips four progressed to avascular necrosis (AVN), which was not seen in the unstable slips. The literature on slipped upper femoral epiphysis suggests that the acute unstable slip is at higher risk of developing AVN. We recommend reduction and stabilisation of unstable slips within 24 hours of the onset of symptoms in order to reduce the risk of AVN.

Shearing of Polymer Drops with Interface Modification

The influence of block copolymers (BCP) and interfacial reaction on the deformation of 30−100 μm polymer drops inside an immiscible polymer matrix was visualized in a parallel plate, counterrotating apparatus. Symmetric diblock copolymers were blended into polypropylene (PP), poly(methyl methacrylate) (PMMA), and polyethylene (PE) homopolymers. These were dispersed as drops in a polystyrene (PS) matrix. Addition of BCP significantly increased the amount of area the deforming drop generates when subjected to simple shear flow. Polymers with terminal amine groups (PMMA and PS) were coupled with maleic anhydride functional PS and PE. This reaction results in the formation of graft copolymer at the interface. These reactive pairs appear to be even more effective than BCP at generating interfacial area. The enhancement in area may be attributed to reduction in interfacial tension or to reduction in slip, but more likely a combination of both and a gradient in interfacial tension.

Clinical Results of Instrumentation Reduction and Posterolateral Fusion After Decompression of Symptomatic Lumbar Spondylolisthesis

From July 1990 to June 1993, 35 patients suffering lumbar spondylolisthesis (21 degenerative; 14 isthmic) were operated on and reviewed. They all had single-level involvement either L4-5 or L5-S1 and only this level was confined for operation. The operative procedures included decompression, posterolateral fusion and pedicle screw instrumentation for fixation and reduction of the vertebral slip. The age ranged from 42 to 65 years old, with an average of 55 years. There were 21 patients with grade 1 slip; 13 with grade II; and 1 with grade III. The follow-up periods ranged from 30 to 55 months with an average of 42 months. The clinical results were evaluated according to the improvement of low back pain, radicular pain, claudication and the incidence of fusion. Twenty-four patients (74%) were rated good to excellent and the fusion rate was 88%. However, there were 16 patients who still suffered from significant low back pain and who had reportd that such pain adversely affected the rating of clinical result. Loss of reduction were found in 16 patients, but there was no difference in clinical outcome between patients with or without reduction loss after the operation. The purpose of this paper is to report the clinical outcomes of the treatment of symptomatic spondylolisthesis with decompression, posterolateral fusion and instrumental reduction of the slip. The incidence of reduction loss and the prevalence of remaining low back pain are two important factors to consider in doing such reduction procedure. We inferred that slip reduction may not be a worthwile procedure in the treatment of adult spondylolisthesis if ordinary posterolateral fusion with short segment instrumentation is contemplated.

SUPERPOSIÇÃO DESTRAL EM AMPLA ZONA DE CISALHAMENTO SINISTRAL: CINTURÃO DE CISALHAMENTO SÃO PAULO, IMEDIAÇÕES DE PIRACAIA - SP

The shear zones in question are roughly NE-SW and intersect gneissic-migmatitic terrains of the Piracaia Complex to the northwest and low- to medium-grade metavolcano-sedimentary sequences of the Sao Roque and Serra do Itaberaba Groups to the southeast. The early Sao Bento do Sapucai and Sertaozinho shear zones (SBSSZ and SSZ) comprise a large mylonitic belt that records sinistral lateral displacement that took place under low to medium metamorphic conditions. This movement generated both widespread subsidence toward the SE and transtensile domains in which less metamorphic rocks and granitic bodies were emplaced. This arrangement (including a probable decrease in the metamorphic grade toward the SE) was disrupted by later dextral displacement of the Jundiuvira Shear Zone (JSZ), a narrower zone of mylonites and ultramylonites with a foliation that is distinguished from the former by retrograde minerais. A SSW to ENE inflection of the JSZ produced both transtensile and transpressive domains, the latter being characterised by asymmetric cylindrical, northwest-verging folds in the SBSSZ region. Lattice preferred orientation (LPO) analysis of quartz C-axes suggests distinct deformational histories for two different parts of the area, whose boundaries are related to the JSZ transpressive domain. In the northwest (SBSSZ) the most typical LPO diagrams show small-circle girdles with asymmetric maxima, which are thought to represent non-coaxial deformation followed by flattening (transpression), while in the southeast (SSZ) the patterns are well-defined sinistral single girdles, typical of non-coaxial deformation (simple shear). The general decrease in metamorphic grade observed in the area is also suggested by the quartz C-axes patterns, which display a reduction in the basal slip (indicative of low temperatures) from the border to the centre of the JSZ.

Spondylolisthesis in children and adolescents.

Isthmic spondylolisthesis occurs in 4.4 % of children. In general it is a benign condition. The majority of individuals with mild or moderate isthmic vertebral slip remain free of symptoms or get only mild symptoms. In children and adolescents with mild slip, primary treatment of pain symptoms is non-operative. Young children before the growth spurt need radiological follow-up for documentation of possible slip progression. If the slip exceeds 25 % in a child, segmental fusion to prevent further progression should be considered. Uninstrumented posterolateral fusion is the method of choice for treatment of pain symptoms not responding to conservative measures in slips up to 50 %. In severe slips ( > 50 %), anterior or combined fusion is necessary to prevent further progression of lumbosacral kyphosis. The clinical and subjective results of in situ fusion in this age group are satisfactory in 80-90 % of cases. Slip reduction is possible. It requires internal fixation and is connected with a higher risk of complications. The results of slip reduction have not yet been shown to be superior to results after in situ fusion. It may be performed in cases of spondyloptosis with severe impairment of function and sagittal malalignment of the spine.

Adding posterior lumbar interbody fusion to pedicle screw fixation and posterolateral fusion after decompression in spondylolytic spondylolisthesis.

This is a retrospective study analyzing 76 patients treated by decompression, pedicle screw instrumentation, and fusion for spondylolytic spondyiolisthesis with symptomatic spinal stenosis. To verify the advantages of adding posterior lumbar interbody fusion to the usual posterolateral fusion with pedicle screw instrumentation. Stabilization after decompression of spondylolytic spondylolisthesis is difficult because of a lack of fusional bone bases, gap between the transverse process bases, and incompetent anterior disc support. Posterior lumbar interbody fusion offers anterior support, reduction, and a broad fusion base. Forty patients were treated with posterolateral fusion, and 36 were treated with additional posterior lumbar interbody fusion. They were compared for union, reduction of the deformity, and clinical results. The patients were followed up for more than 2 years. Nonunion was observed in three patients who underwent posterolateral fusion (7.5%), and no cases of nonunion was found in patients who underwent posterior lumbar interbody fusion. Reduction of slippage was 28.3% in those who underwent posterolateral fusion and 41.6% in those who had posterior lumbar interbody fusion (P = 0.05). In the posterolateral fusion group, eight patients (20%) had recurrence of deformity, with loss of reduction more than 50%. Hardware failures occurred in two patients who had posterolateral fusion. There was no major neurologic complications in both groups. Both groups had satisfactory results in more than 90% of patients, with marked improvement of claudication. However, subjective improvement of back pain by Kirkaldy-Willis criteria revealed differences in the excellent results. An excellent result was reported by 45% in the posterolateral fusion group and by 75% in posterior lumbar interbody fusion group. The addition of posterior lumbar interbody fusion to posterolateral fusion after a complete decompression and pedicle screw fixation is a recommended procedure for the treatment of spondylolytic spondylolishesis with spinal stenosis.

Spondylolisthesis in childhood and adolescence

Isthmic spondylolisthesis occurs in 4.4% of children. In general it is a benign condition. The majority of individuals with mild or moderate isthmic vertebral slip remain free of symptoms or get only mild symptoms. In children and adolescents with mild slip, primary treatment of pain symptoms is non-operative. Young children before the growth spurt need radiological follow-up for documentation of possible slip progression. If the slip exceeds 25% in a child, segmental fusion to prevent further progression should be considered. Uninstrumented posterolateral fusion is the method of choice for treatment of pain symptoms not responding to conservative measures in slips up to 50%. In severe slips (> 50%), anterior or combined fusion is necessary to prevent further progression of lumbosacral kyphosis. The clinical and subjective results of in situ fusion in this age group are satisfactory in 80-90% of cases. Slip reduction is possible. It requires internal fixation and is connected with a higher risk of complications. The results of slip reduction have not yet been shown to be superior to results after in situ fusion. It may be performed in cases of spondyloptosis with severe impairment of function and sagittal malalignment of the spine.

Frictional action at lower limb/prosthetic socket interface

The frictional action at stump/socket interface is discussed by a simplified model and finite element model analyses and clinical pressure measurements. The friction applied to the stump skin produces stresses within tissues and these stresses may damage the tissues and affect their normal functions. The combination of normal and shear stresses is considered to be a critical factor leading to amputee's discomfort and tissue damage. However, friction at the stump/socket interface has a beneficial action. A simplified residual limb model and a finite element model using real geometry have been developed to analyse the support action of friction. Both results show that the friction plays a critical role both in supporting the load of the amputee's body during the support phase of the gait cycle and in preventing the prosthesis from slipping off the limb during swing phase. Pressures at the below-knee socket during walking were measured with conditions of different friction. The results reveal that a larger pressure was produced at the lubricated interface than at the normal interface. A proper choice of coefficient of friction will balance the requirements of relief of load stress and reduction of slip with the general ability to support loads.

腰椎変性疾患に対するＳｔｅｆｆｅｅ ＶＳＰ ｓｙｓｔｅｍおよび後方経路椎間固定（ＰＬＩＦ）の適応と限界

Fifteen patients were treated by posterior lumbar interbody fusion using the Steffee VSP system for degenerative lumbar spine lesions. They were evaluated independently with an average follow-up of 1 year. Fusion rates were 94% (15/16). Anterior slipping was well reduced and the alignment was corrected. Acceptable clinical results were seen in most of the patients with low back and leg pain. However, several problems remain in the reduction and alignment-corrertion of lateral slip of the lumbar spine. In addition, treatment of patients with osteoporosis or long term hemodialysis required careful surgical technique and extensive external fixation.

The reduction of slip and fall injuries: Part II — The scientific basis (knowledge base) for the guide

The coefficient of friction (COF) between the shoe material and the walking surface is clearly of significance to slipping accidents. Friction is classically measured in one of the two ways. Three basic approaches have been used in the past to measure friction coefficients—(1) pulling an instrumented load across the surface, (2) allowing a pendulum to strike the surface under test, and (3) displacing an articulated strut. Currently, the most widely used technique for measuring COF is based on the original James machine, called the American Society for Testing and Materials (ASTM) method. The main purpose of such a machine is to establish the static COF of various walking surfaces, and the test utilizes specially prepared leather and floor surfaces to achieve repeatability. Experiments have indicated that people manipulate gait when walking on slippery surfaces. Proprioceptive recognition of the slipperiness of the surface is probably automatically monitored during walking to allow these adjustments to be made. Discontinuities in surface slipperiness have been implicated as a significant factor in many slips, and these occur when the subject, walking on an accustomed surface, unexpectedly encounters a patch with lower frictional characteristics or of higher frictional characteristics.