Posterior Slip Research Articles

Risk factors and clinical significance of posterior slip of the proximal vertebral body after lower lumbar fusion.

Adjacent segment disease (ASD) after fusion surgery is frequently manifests as a cranial segment instability, disc herniation, spinal canal stenosis, spondylolisthesis or retrolisthesis. The risk factors and mechanisms of ASD have been widely discussed but never clearly defined. To investigate the risk factors and clinical significance of retrograde movement of the proximal vertebral body after lower lumbar fusion. This was a retrospective analysis of the clinical data of patients who underwent transforaminal lumbar interbody fusion surgery between September 2015 and July 2021 and who were followed up for more than 2 years. Ninety-one patients with degenerative lumbar diseases were included (22 males and 69 females), with an average age of 52.3 years (40-73 years). According to whether there was retrograde movement of the adjacent vertebral body on postoperative X-rays, the patients were divided into retrograde and nonretrograde groups. The sagittal parameters of the spine and pelvis were evaluated before surgery, after surgery, and at the final follow-up. At the same time, the Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) were used to evaluate the patients' quality of life. Nineteen patients (20.9%) who experienced retrograde movement of proximal adjacent segments were included in this study. The pelvic incidence (PI) of the patients in the retrograde group were significantly higher than those of the patients in the nonretrograde group before surgery, after surgery and at the final follow-up (P < 0.05). There was no significant difference in lumbar lordosis (LL) between the two groups before the operation, but LL in the retrograde group was significantly greater than that in the nonretrograde group postoperatively and at the final follow-up. No significant differences were detected in terms of the |PI-LL|, and there was no significant difference in the preoperative lordosis distribution index (LDI) between the two groups. The LDIs of the retrograde group were 68.1% ± 11.5% and 67.2% ± 11.9%, respectively, which were significantly lower than those of the nonretrograde group (75.7% ± 10.4% and 74.3% ± 9.4%, respectively) (P < 0.05). Moreover, the patients in the retrograde group had a greater incidence of a LDI < 50% than those in the nonretrograde group (P < 0.05). There were no significant differences in the ODI or VAS scores between the two groups before the operation, but the ODI and VAS scores in the retrograde group were significantly worse than those in the nonretrograde group after the operation and at the last follow-up, (P < 0.05). The incidence of posterior slippage after lower lumbar fusion was approximately 20.9%. The risk factors are related to a higher PI and distribution of lumbar lordosis. When a patient has a high PI and insufficient reconstruction of the lower lumbar spine, adjacent segment compensation via posterior vertebral body slippage is one of the factors that significantly affects surgical outcomes.

Is radiographic lumbar spondylolisthesis associated with occupational exposures? Findings from a nested case control study within the Wakayama spine study

BackgroundTo explore the relationship between radiographic spondylolisthesis and occupational factors in a case-control study nested within the Wakayama Spine Study (WSS).MethodsThe WSS is a cross-sectional observational study amongst Japanese adults. All participants completed a lifetime occupational history and underwent X-rays of the lumbar spine (L1-S1) according to a pre-defined protocol. One trained surgeon graded the presence of a spondylolisthesis based upon ≥5% anterior or posterior slip at one or more levels. Cases, with lumbar spondylolisthesis, were compared with controls without, for their principal occupation and occupational exposures.ResultsIn total, data were available for 722 adults (245 men and 477 women), mean age 70.1 (range 53–93) years. According to the pre-defined radiographic criteria, 117 were defined with spondylolisthesis (cases), leaving 605 controls. Cases were not significantly different from controls for age, gender, BMI, smoking or alcohol intake. However, cases were more than twice as likely to report occupational driving ≥4 h/day (OR 2.39, 95% CI 1.08–5.27) after adjustment for age, gender and BMI. Additionally, after stratification by age using 75 years as a cut-point, cases were more than 3-fold more likely to report having worked in the agricultural/ fishing industries (OR 3.47, 95% CI 1.29–9.29) among those aged < 75 years. A reduced risk of being a case was associated with climbing slopes/steps and walking.ConclusionsA history of occupational driving and working in the agricultural/fishing industry were associated with radiographic spondylolisthesis in this cross-sectional population study. This finding requires further evaluation in longitudinal studies.

Accounting for uncertain fault geometry in earthquake source inversions – I: theory and simplified application

The ill-posed nature of earthquake source estimation derives from several factors including the quality and quantity of available observations and the fidelity of our forward theory. Observational errors are usually accounted for in the inversion process. Epistemic errors, which stem from our simplified description of the forward problem, are rarely dealt with despite their potential to bias the estimate of a source model. In this study, we explore the impact of uncertainties related to the choice of a fault geometry in source inversion problems. The geometry of a fault structure is generally reduced to a set of parameters, such as position, strike and dip, for one or a few planar fault segments. While some of these parameters can be solved for, more often they are fixed to an uncertain value. We propose a practical framework to address this limitation by following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We develop a sensitivity analysis to small perturbations of fault dip and position. The uncertainties of our fixed fault geometry are included in the inverse problem under the formulation of the misfit covariance matrix that combines both prediction and observation uncertainties. We validate this approach with the simplified case of a fault that extends infinitely along strike, using both Bayesian and optimization formulations of a static slip inversion. If epistemic errors are ignored, predictions are overconfident in the data and slip parameters are not reliably estimated. In contrast, inclusion of uncertainties in fault geometry allows us to infer a robust posterior slip model. Epistemic uncertainties can be many orders of magnitude larger than observational errors for great earthquakes (Mw > 8). Not accounting for uncertainties in fault geometry may partly explain observed shallow slip deficits for continental earthquakes. Similarly, ignoring the impact of epistemic errors can also bias estimates of near-surface slip and predictions of tsunamis induced by megathrust earthquakes.

Transforaminal lumbar interbody fusion in treating degenerative spondylolisthesis at L 4 with kyphotic versus non-kyphotic angulation

Objective To compare the radiographic and clinical results of transforaminal lumbar interbody fusion(TLIF) in the treatment of degenerative spondylolisthesis (DS) with or without kyphotic angulation. Methods This study retrospectively reviewed a consecutive cohort of 137 patients with L4 DS (Meyerding grade I or II) who received TLIF between January 2009 and December 2012 and had a minimum follow-up of 2 years, including 24 males and 113 females, with the average age of 59.1±11.6 years (45-72 years) . The enrolled patients were divided into two groups based on the angulation of intervertebral space: the kyphotic group and the non-kyphotic group. Slip angle (SA), anterior disc height (ADH), posterior disc height (PDH), slip percentage (SP) and segmental kyphosis (SK) was measured to evaluate the radiographic outcomes. Oswestry disability index (ODI) and visual analogue scale (VAS) was collected to evaluate the clinical results. The radiographic measurements and clinical indexes were recorded before and after surgery and at latest follow-up. The independent samples t test was performed to analyze the differences between the two groups in terms of radiographic and clinical outcomes. Results Kyphotic slip was observed in 21(15.3%) patients, while non-kyphotic slip in 116 (84.7%) patients. No significant difference was observed in terms of age, gender, operation time and blood loss between the two groups. The preoperative SA in kyphotic and non-kyphotic group was 3.1°±2.3° and -8.2°±4.7°, respectively. The kyphotic group had significantly lower ADH and higher PDH than the non-kyphotic group, while there was no significant difference in SP between the two groups. After surgery, the postoperative and latest follow up radiographic results showed that patients of both groups had significant improvement, without significant differences between groups in terms of ADH, PDH, SA and SK, but the reduction of slip was significantly higher in the kyphotic group. Postoperative and follow-up ODI and VAS scores demonstrated remarkable improvement after surgery, without difference between groups, despite being higher in the kyphotic group than the non-kyphotic group preoperatively. Conclusion The kyphotic angulation of intervertebral space benefits to and facilitates slip reduction for L 4 DS via TLIF procedure, and achieves improvements in life quality which is similar to the nonkyphotic group. Key words: Lumbar vertebrae; Intervertebral disc degeneration; Spondylolysis; Spinal fusion; Quality of life

Preoperative retrolisthesis as a predictive risk factor of reoperation due to delayed-onset symptomatic foraminal stenosis after central decompression for lumbar canal stenosis without fusion

Background ContextFor patients diagnosed with lumbar central canal stenosis with asymptomatic foraminal stenosis (FS), surgeons occasionally only decompress central stenosis and preserve asymptomatic FS. These surgeries have the potential risk of converting preoperative asymptomatic FS into symptomatic FS postoperatively by accelerating spinal degeneration, which requires reoperation. However, little is known about delayed-onset symptomatic FS postoperatively. PurposeThis study aimed to evaluate the rate of reoperation for delayed-onset symptomatic FS after lumbar central canal decompression in patients with preoperative asymptomatic FS, and determine the predictive risk factors of those reoperations. Study DesignThis study is a retrospective cohort study. Patient SampleTwo hundred eight consecutive patients undergoing posterior central decompression for lumbar canal stenosis between January 2009 and June 2014 were included in this study. Outcome MeasuresThe number of patients who had preoperative FS and the reoperation rate for delayed-onset symptomatic FS at the index levels were the outcome measures. MethodsPatients were divided into two groups with and without preoperative asymptomatic FS at the decompressed levels. The baseline characteristics and revision rates for delayed-onset symptomatic FS were compared between the two groups. Predictive risk factors for such reoperations were determined using multivariate logistic regression and receiver operating characteristics analyses. ResultsPreoperatively, 118 patients (56.7%) had asymptomatic FS. Of those, 18 patients (15.3%) underwent reoperation for delayed-onset symptomatic FS at a mean of 1.9 years after the initial surgery. Posterior slip in neutral position and posterior extension-neutral translation were significant risk factors for reoperation due to FS. The optimal cutoff values of posterior slip in neutral position and posterior extension-neutral translation for predicting the occurrence of such reoperations were both 1 mm; 66.7% of patients who met both of these cutoff values had undergone reoperation. ConclusionsThis study demonstrated that 15.3% of patients with preoperative asymptomatic FS underwent reoperation for delayed-onset symptomatic FS at the index levels at a mean of 1.9 years after central decompression, and preoperative retrolisthesis was a predictive risk factor for such a reoperation. These findings are valuable for establishing standards of appropriate treatment strategies in patients with lumbar central canal stenosis with asymptomatic FS.

Percutaneous endoscopic lumbar discectomy for lateral disc herniation cranially migrated in the stenotic foramen caused by posterior slip of L3 vertebra

Percutaneous endoscopic lumbar discectomy for lateral disc herniation cranially migrated in the stenotic foramen caused by posterior slip of L3 vertebra

Variation in the insertion of the latissimus dorsi & its clinical importance

The latissimus dorsi is the larger, flat, dorso-lateral muscle on the trunk, posterior to the arm, and partly covered by the trapezius on its median dorsal region. Origin of the latissimus dorsi is from spinous processes of thoracic T7–T12, thoracolumbar fascia, iliac crest and inferior 3 or 4 ribs, inferior angle of scapula and insertion on floor of intertubercular groove of the humerus. We have studied 50 cadavers in the different medical colleges in which we found 2% case of anterior and posterior slip of the muscle fibers with their extension up to the pectoralis major and teres major respectively. Usually, latissimus dorsi involve in extension, adduction, transverse extension also known as horizontal abduction, flexion from an extended position, and internal rotation of the shoulder joint. It also has a synergistic role in extension and lateral flexion of the lumbar spine. The latissimus dorsi may be used for the tendon graft surgeries. Tight latissimus dorsi has been shown to be one cause of chronic shoulder pain and chronic back pain. Because the latissimus dorsi connects the spine to the humerus, tightness in this muscle can manifest as either sub-optimal glenohumeral joint function (which leads to chronic shoulder pain) or tendinitis in the tendinous fasciae connecting the latissimus dorsi to the thoracic and lumbar spine. Latissimus dorsi used for pedicle transplant rotator cuff repair reconstruction of breast, face, scalp and cranium defect. The extra slip of the latissimus dorsi may puzzle any transplant operations. We as anatomist discuss the clinical implication of the extra slip of latissimus dorsi.

Uncertainties in probability of occurrence of strong earthquakes for fault sources in the Central Apennines, Italy

Using the characteristic earthquake model, we calculate the probability of occurrence of earthquakes M w > 5.5 for individual fault sources in the Central Apennines for the 30-year period (2007–2037). We show the effect of time-dependent and time-independent occurrence (Brownian passage time (BPT) and Poisson) models together with uncertain slip rates and uncertain maximum magnitudes and, hence, uncertain recurrence times. In order to reduce the large prior geological slip rate uncertainty distribution for most faults, we obtain a posterior slip rate uncertainty distribution using a likelihood function obtained from regional historical seismicity. We assess the uncertainty of maximum magnitude by assuming that the uncertainty in fault width and length are described by a normal distribution with standard deviation equal to ±20% of the mean values. We then estimate the uncertainties of the 30-year probability of occurrence of a characteristic event using a Monte Carlo procedure. Uncertainty on each parameter is represented by the 16th and the 84th percentiles of simulated values. These percentiles bound the range that has a 68% probability of including the real value of the parameter. We do these both for the Poisson case and for the BPT case by varying the aperiodicity parameter (α value) using the values 0.3, 0.5, and 0.7. The Bayesian posterior slip rate uncertainties typically differ by a factor of about 2 from the 16th to the 84th percentile. Occurrence probabilities for the next 30 years at the 84th percentile typically range from 1% to 2% for faults where the Poisson model dominates and from 2% to 21% where one of the BPT models dominates. The uncertainty in occurrence probability under the time-dependent hypothesis is very large, when measured by the ratio of the 84th to the 16th percentile, frequently being as much as two orders of magnitude. On the other hand, when measured by standard deviation, these standard deviations range from 2% to 6% for those faults whose elapsed time since previous event is large, but always 2% or less for faults with relatively recent previous occurrence, because the probability of occurrence is always small.

RELATIONSHIP OF FRONTAL PLANE CENTER OF MASS CONTROL VARIABLES TO SLIP OUTCOMES.

Purpose/Hypothesis: The purpose of this study is two fold: to investigate, in unperturbed walking, whether step width or frontal plane center of mass (COM) control can predict a person's ability to recover from an induced slip; and to investigate the extent to which frontal plane COM and BOS control during an anterior posterior (A-P) slip affect the outcome of the slip. We hypothesize that the step width and frontal plane COM control exhibited during natural gait and during the first, unexpected slip, will differentiate between those who will be able to recover from an induced slip and those who will not. Subjects: 34 healthy adults, 65 years and older. Materials/Methods: Subjects walked on an instrumented walkway while wearing a safety harness during motion capture of their regular gait. After 10 unperturbed trials, an AP slip was induced unexpectedly under the right heel at touchdown (TD). Motion data were used to calculate the frontal plane variables step width, COM position, normalized COM position, and COM velocity. These were calculated at right heel TD, left foot lift off (LO), and subsequent right foot touchdown (RCTD). Subjects were grouped by outcome of the first slip trial into the fall or the recover group. T-tests were used to compare the frontal plane variables at the three gait instants for the fall vs. the recover group for natural walking and for the slip trial. Results: Upon the first slip, all 34 subjects experienced a loss of balance: 19 subjects fell (fall group), the other 15 did not (recover group). During unperturbed walking, at TD and LO, there were no differences in the frontal plane variables between the fall group and the recover group. At left touchdown (RCTD), there were small, but significant differences in the lateral position of the COM and the step width between the two groups; but no differences in normalized COM position or COM velocity. At the three gait instants examined during the first, unexpected slip, there were no differences between the fall group and the recover group in step width, or any of the other frontal plane COM variables measured. Conclusions: Altered frontal plane center of mass control in stance, stepping, normal walking, and perturbed gait, as well as increased step width during gait, have been implicated as risk factors for falling associated with aging. We, therefore, expected step width and frontal plane COM control during natural walking and throughout a slip to be different between the group who fell as a result of the slip and those who were able to recover. We found only small differences during natural walking and none during the slip. Clinical Relevance: Balance and gait training in older adults which have the goal of fall prevention should focus on those areas which pre-dispose one to falling. In this case, step width and lateral control of the body's COM, during natural gait and during a slip, appear not to have been, as is frequently believed, related to the subject's ability to recover from an induced slip.

Computerized Navigation for Treatment of Slipped Femoral Capital Epiphysis

In situ pinning with a single screw is the treatment of choice for symptomatic slipped capital femoral epiphysis (SCFE). Some technical features are critical and include proper screw entry point, screw direction in relation to the epiphysis, and the length of screw. These are complicated by the deformity created as a result of the posterior slip of the epiphysis. Fluoroscopic based computerized navigation system can increase precision in screw placement while performing the surgical task, and markedly reduce radiation. By using real fluoroscopy-based navigation, the screw can be placed with only two fluoroscopic images. Entry point, length, and precise direction can all be easily determined through this technique.

Preoperative assessment for intertrochanteric femoral osteotomies in severe chronic slipped capital femoral epiphysis using computed tomography

We propose here to focus on preoperative assessment for intertrochanteric femoral osteotomies in severe slipped capital femoral epiphysis (SCFE) using computed tomography. This intertrochanteric osteotomy was preoperatively customized for each chronic SCFE patient treated, and has been performed on 22 patients with an average posterior slip angle of 55 degrees. The osteotomy is planned with images from computed tomography as follows. The angle between a provisional axis on one image and the axis of the lateral aspect of the femur on the other image is defined as alpha. When the alpha angle varies from 20 to 30 degrees, a simple flexion osteotomy is selected for correction along the axis of the lateral femur; when the alpha angle is more than 30 degrees, a flexion osteotomy along with some valgus correction should be considered; when the alpha angle is less than 20 degrees, varus correction should be added. The postoperative posterior slip angle, head-shaft angle (P < 0.05) and epiphyseal height ratio (P < 0.005) in the group using our method were superior to the Southwick group. Postoperative hip motion was nearly the same as the unaffected side. The average leg length discrepancy was 0.9 cm (range, from 0 to 2.0 cm). Reduced blood loss (P < 0.001) and shorter operation time (P < 0.001) were also noted, compared with the Southwick group. We concluded that the intertrochanteric femoral osteotomy based on this strategy minimizes the surgical complexity, resulting in a more anatomic reduction of the capital femoral epiphysis.

Surgical Treatment of Morbid Obesity by Adjustable Gastric Band: the Case for a Conservative Strategy in the Case of Failure – a 9-Year Series

Lapaparoscopic adjustable gastric banding (LAGB) has become a widespread method to treat morbid obesity. Long-term complications and failures require a strategy for reoperation. 1,180 patients have been operated on from April 1995 to December 2003. 151 had reoperation for complications (12.7%) excluding access-port problems: slippage (105), erosion (22), intolerance (24). 67 patients (5.6%) had their band removed; only 5 had a switch to another procedure. Esophageal dilatation and insufficient excess weight loss (<25%) after 5 years (13.7%) should also be addressed. Two situations are described: 1) Band in place: anterior slip, dilatation, isolated insufficient weight loss. 2) Band to be removed: posterior slip, severe anterior slip (acute, with necrosis or perforation), erosion, intolerance. Four options are recognized: 1) Conservation (adjustment management) or surgical correction (anterior slip). 2) Placement of a new band: for failure of the device, accidental removal (slippage in difficult conditions), and erosion after a delay. 3) RYGBP or BPD in selected cases only. 4) Other procedures. 1) A new band can be placed if there has been a technical problem. 2) Weight control is possible, including in the case of esophageal dilatation. Reoperation for insufficient weight loss without a technical problem is not an option. Failures of VBG cannot be fairly compared with Lap-Band (R) failures because of adjustability. 3) Reoperation is not often demanded. For failure after LAGB, the future should involve less invasive bariatric procedures and nonsurgical approaches.

Slipped Capital Femoral Epiphysis*†

Loder, Randall T. M.D.‡; Aronsson, David D. M.D.§; Dobbs, Matthew B. M.D.#; Weinstein, Stuart L. M.D.# Author Information

The geometry of slipped capital femoral epiphysis: implications for movement, impingement, and corrective osteotomy.

Metaphyseal impingement limits motion in high-grade slipped capital femoral epiphysis (SCFE). A three-dimensional volume/surface computer model was used to study the geometry of impingement, which may take the form of impaction, which causes levering or requires compensatory alteration in motion, or inclusion that occurs after remodeling and may lead to acetabular cartilage damage. The majority of deformities seen clinically can be reproduced with posterior epiphyseal displacement in the plane of the physis. By using the 3-D movements of normal walking, this model predicts little anterior metaphyseal impingement in the normal hip. As posterior slip angle increases to 25 degrees , minor impingement can be eliminated with as little as 20 degrees of external rotation. High-grade posterior slips (75 degrees ) require external rotation of 50-60 degrees during walking to minimize impaction. Sitting increases impingement for all slip geometries, requiring proportionately greater external rotation. As remodeling restores a more normal arc of motion, an increasing proportion of the femoral head is composed of the remodeled, included metaphyseal prominence. This study explores the potential role of contact between the acetabulum and the metaphysis in the production of abnormal range of motion after SCFE, and simulation estimates the correction needed by osteotomy to allow normal walking and sitting. The inclusion of significant metaphyseal surfaces in the remodeled hip may be one factor in subsequent degenerative changes associated with SCFE.

腰椎椎間板障害等を合併した骨折を伴い変形を有する脊椎骨粗しょう症の検討

We studied 34 cases with both symptomatic degenerative disc lesions and spondyloporosis accompained by vetebral fracture and deformities, to investigate the influence these factors have on each other.All patents were female, with a mean of 77.2 years. The average follow-up period was 4 years 11 months.Slips such as degenerative spondylolisthesis, posterior slip, isthmic spondylolisthesis was proven in 23 cases.The vertebral fractures were located from T8 to L4, with most seen from T11 to L1 levels.26 cases had sciatic symptoms.Tenderness was reported in all cases at lower lumbar levels (disc lesion level), in 25 cases it was also shown at the level of the vertebral fractures.In 4 cases, sciatic symptoms developed after the vertebral fractures were found at another levels.Intractable Knee joint disability was also documented in 16 cases.

腰仙椎部後方すべりのＸ線学的検討

We performed a radiological study to assess morphological features of the lumbo-sacral spine contribute to posterior slip of the lumbar spine. Padiological measurements were carreid out in 147 cases of retrolisthesis, 30 cases of retro-position of L5 spine and a control group of 408 cases of low cack pain. The incidence of posterior slip in the controls was 26%.The average age was younger in the posterior slip group compared to the control group, and the retro-position group were younger than the retrolisthesis group.A higher incidence of lumbo-sacral transitional vertebrae was noted in the posterior slip group than in a control group. Also the angle between the superior surface and the posterior border of the sacral vertebral body was lower in the posterior slip group.The laminar angle was similar in the posterior slip group and controls.In conclusion, special morphological features such as low posterior superior sacral angles and the existence of lumbo-sacral transitional vertebrae were considered to be risk factor for the development of posterior slip.

Late radiographic findings after anterior cervical fusion for spondylotic myeloradiculopathy.

A retrospective study was performed to evaluate the radiographic changes that occurred at spinal levels adjacent to fused vertebrae after anterior cervical fusion. One hundred six patients with cervical spondylotic myeloradiculopathy (88 men, 18 women) were followed for an average of 8.5 years. The average age at follow-up was 64 years. Forty-two patients underwent a single-level fusion, 52 had a two-level fusion, and 12 had three levels fused. Seventeen patients who underwent additional surgery after anterior fusion also were reviewed, with an average follow-up period of 2.9 years. Postoperatively, cervical flexion-extension resulted in significantly increased movement about the vertebral interspace at the upper adjacent level. An increment of posterior slip of the vertebra immediately above the fusion level, with associated spinal canal compromise of less than 12 mm, significantly affected neurologic results. Patients with multilevel fusions notably exhibited these radiographic abnormalities at adjacent levels. Spinal canal stenosis, when associated with dynamic spinal canal stenosis in the vertebra above the fusion level, affected late neurologic results. Results of salvage laminoplasty were not satisfactory. Unnecessarily extended longer fusion must be avoided.

Pseudarthrosis and delayed union after anterior cervical fusion

Anterior cervical spine fusion was carried out on 443 cases between 1965 and 1988 with pseudarthrosis or delayed union in 15 (3.4%). The causes of these complications were malalignment and faulty postoperative care. Symptoms resulted from abnormal mobility, cord compression due to posterior slip or rotation of the upper vertebral body, kyphotic deformity or a problem at the adjacent level. Four out 5 cases with symptoms recovered successfully after a second operation.

腰仙移行椎とその上位椎のすべりについて

To study the several changes of the disc just above the lumbo-sacral transitional vertebrae, the features of slipping at this level were examined in 216 patients who had lumbo-sacral transitional vertebrae in both anterior and posterior sides.Type II and type III of modified Custivelli's classification for the posterior element and the modified Wigh's Classification for anterior element were employed for this purpose. The results were compared with 597 patients with low back pain who visited our clinic.Isthmus spondylolisthesis (8 cases, 3.7%) was almost same as the frequency in our low back pain patients. The slight increase was shown in degenerative spondylolisthesis (30 cases, 14%). The greater incidence was proved in posterior slip (115 cases, 52.3%) in this series compared to the our low back pain group (19%). The almost same incidence was shown in young group and in old group. The slight increase was found in type I and type II in the anterior classication and in type IIb and type IIIb in the posterior classification. In conclusion, posterior slip at the spine just above the lumbo-sacral transitional vertebrae was one of the special features.

Unstable cervical spine in athetoid cerebral palsy.

The manifestations and pathomechanism of cervical instability of the athetoid neck in cerebral palsy (CP) patients was clarified in this study by means of static and dynamic x-ray analysis. Instability was defined as follows: 1) listhesis indicating anterior or posterior slip of more than 3 mm and/or 2) sagittal rotation between two vertebrae beyond the normal range measured by Penning. Cervical instability fitting this definition mainly took place in the upper and middle cervical disc levels, such as C3-4, C4-5, and/or occasionally C5-6. These coincide with the disc levels adjacent to the apex of the lordotic curve and/or those around the transitional vertebrae between the two reversed curves that render the cervical spine S-shaped in athetoid CP. A large facet angle at the apex vertebra facilitated anterior and/or posterior listhesis of the vertebrae. Conversely, a sudden decrease in the facet angle around the transitional vertebra in S-shaped curves precipitated deflection of the spine and increased sagittal rotation at this level. In addition to these structural abnormalities, rapid and repetitious neck movements seemed to accelerate the progression of cervical instability in athetoid CP patients.