Identifying Acute Lumbar Spondylolysis in Young Athletes with Low Back Pain: Retrospective Classification and Regression Tree Analysis

STUDY DESIGN

Case-control study.

OBJECTIVE

The aim of this study was to establish an algorithm to distinguish acute lumbar spondylolysis (LS) from nonspecific low back pain (NSLBP) among patients in junior high school by classification and regression tree (CART) analysis.

SUMMARY OF BACKGROUND DATA

Rapid identification of acute LS is important because delayed diagnosis may result in pseudarthrosis in the pars interarticularis. To diagnose acute LS, magnetic resonance imaging (MRI) or computed tomography is necessary. However, not all adolescent patients with low back pain (LBP) can access these technologies. Therefore, a clinical algorithm that can detect acute LS is needed.

METHODS

The medical records of 223 junior high school-aged patients with diagnosed acute NSLBP or LS verified by MRI were reviewed. A total of 200 patients were examined for establishing the algorithm and 23 were employed for testing the performance of the algorithm. CART analysis was applied to establish the algorithm using the following data; age, sex, school grades, days after symptom onset, history of LBP, days of past LBP, height, passive straight leg raising test results, hours per week spent in sports activities, existence of spina bifida, lumbar lordosis angle, and lumbosacral joint angle. Sensitivity and specificity of the algorithm and the area under the ROC curve were calculated to assess algorithm performance.

RESULTS

The algorithm revealed that sex, days after symptom onset, days of past LBP, hours per week spent in sports activities, and existence of spina bifida were key predictors for identifying acute LS versus NSLBP. Algorithm sensitivity was 0.64, specificity was 0.92, and the area under the ROC curve was 0.79.

CONCLUSION

The algorithm can be used in clinical practice to distinguish acute LS from NSLBP in junior high school athletes, although referral to MRI may be necessary for definitive diagnosis considering the algorithm's sensitivity.Level of Evidence: 4.

Outcome of Conservative Management in the Treatment of Symptomatic Spondylolysis and Grade I Spondylolisthesis

BACKGROUND

Bracing (thoraco-lumbar-sacral orthosis) has been accepted as mainstay of treatment for symptomatic spondylolysis (SP) and grade I spondylolisthesis (SPL1). However, increasing costs and patient noncompliance can make bracing prohibitive and difficult to manage. The purpose of this study was to determine if SP and SPL1 can be effectively treated using physical therapy and other non-bracing conservative management techniques in order to relieve pain and restore physical function.

METHODS

We performed a cross-sectional study in which patients who presented from June 1, 2004, to May 1, 2015, with symptomatic SP and SPL1 who were treated with nonbracing conservative management, entailing a universal 6-week physical therapy program and restriction of offending activity, were considered for the study. Physical therapy included core strengthening activities, hamstrings stretching, and spine range of motion exercises. Patients meeting inclusion criteria were contacted via phone interview and asked to complete an Oswestry Disability Questionnaire (ODQ) in order to generate a disability score to assess their current pain and daily function. Patients were then stratified into groups based on their level of disability as denoted by their disability score; minimal disability = disability score of 0% to 19.9%, moderate disability = 20% to 39.9%, severe disability = 40% to 59.9%, crippled = 60% to 79.9%, and bed bound or exaggerating = 80% to 100%.

RESULTS

Fourty-six patients were identified as meeting inclusion criteria (28 with SP and 18 with SPL1). Twenty-three of 46 were successfully contacted and agreed to complete the ODQ (10/23 with SP and 13/23 with SPL1). Twenty-two of 23 (96%) patients had a minimal disability score (0% to 19.9%), One of 23 (4%) patients had a moderate disability score (20% to 39.9%), and 18/23 (78%) patients had a disability score of zero, denoting no pain or limitation of function.

CONCLUSION

The results of this study suggest that, in patients with symptomatic spondylolysis and grade I spondylolisthesis, pain relief and restoration of function can be achieved using conservative management techniques without use of a brace.

Is Preventative Long-Segment Surgery for Multi-Level Spondylolysis Necessary? A Finite Element Analysis Study

Objective

For multi-level spondylolysis patients, surgeons commonly choose to fix all the segments with pars interarticularis defect even those without slippage and not responsible for clinical symptoms. In this study, we tried to study the necessity of the preventative long-segment surgery for the defected segment without slippage in treatment of multi-level spondylolysis patients from a biomechanical perspective.

Method

We established a bi-level spondylolysis model with pars defects at L4 and L5 segments, and simulated posterior lumbar interbody fusion (PLIF) and pedicle screw fixation at L5-S1 level. Then we compared the biomechanical changes at L4 segment before and after surgery in neutral, flexion, extension, lateral bending and axial rotation position.

Results

The stress on L4 pars interarticularis was very similar before and after surgery, and reached the highest in axial rotation. The L3-L4 intradiscal pressure was almost the same, while L4-L5 intradiscal pressure changed a little in lateral bending (increase from 1.993 to 2.160 MPa) and axial rotation (decrease from 1.639 to 1.307 MPa) after surgery. The PLIF surgery caused a little increase of range of motion at adjacent L4-L5 and L3-L4 levels, but the change is very tiny (1 degree).

Conclusion

The PLIF surgery will not cause significant biomechanical change at adjacent segment with pars defect in multi-level spondylolysis. On the contrary, excessive long-segment surgery will damage surrounding soft tissues which are important for maintaining the stability of spine. So a preventative long-segment surgery is not necessary for multi-level spondylolysis as long as there are no soft tissue degeneration signs at adjacent level.

[Clinical research progress of direct surgical repair of lumbar spondylolysis in young patients]

OBJECTIVE

To review and summarize the surgical techniques and their outcomes for the treatment of lumbar spondylolysis in young patients by direct surgical repair.

METHODS

Both home and abroad literature on the surgical techniques and their outcomes respectively for the treatment of lumbar spondylolysis in young patients by direct surgical repair was reviewed extensively and summarized.

RESULTS

Direct surgical repair of lumbar spondylolysis can offer a simple reduction and fixation for the injured vertebra, which is also in accord with normal anatomy and physiology. In this way, normal anatomy of vertebra can be sustained. As reported surgical techniques of direct repair, such as single lag screw, hook screw, cerclage wire, pedicle screw cable, pedicle screw rod, and pedicle screw hook system, they all can provide acceptable results for lumbar spondylolysis in young patients. Furthermore, to comply strictly with the inclusion criteria of surgical management and select the appropriate internal fixation can also contribute to a good effectiveness. Within the various methods of internal fixation, pedicle screw hook system has been widely recognized.

CONCLUSION

Pedicle screw hook system fixation is simple and safe clinically. With the gradual improvement of this method and the development of minimally invasive technologies, it will have broad application prospects.

[Direct repair of adolescent lumbar spondylolysis using a pedicle screw-laminar hook system by paramedian approach]

OBJECTIVE

To discuss the indication and clinical effect of direct repair of adolescent lumbar spondylolysis by screw-laminar hook system.

METHODS

From August 2003 to December 2008, 28 patients (13 males and 15 females,ranging in age from 15 and 26 years, averaged 21.6 years) with lumbar spondylolysis were treated with isthmic bone grafting and internal fixation with a pedicle screw-laminar hook system. Three patients had spondylolysis at L3, L4; 5 patients had spondylolysis at L4, L5; 8 patients had spondylolysis at L4; and 12 patients had spondylolysis at L5. All the patients had low back pain and lasted over 6 months. According to preoperative and postoperative plain radiograph, CT scan and Macnab criteria, the fusion rate and clinical effect of this technique were evaluated.

RESULTS

All the patients were followed up with a mean period of 14.9 months, ranging from 9 to 24 months. All the patients had bony union according to the X-rays and CT scan. According to the calculation results of Macnab criteria, 22 patients got an excellent result, 5 good and 1 fair.

CONCLUSION

The direct repair of adolescent lumbar spondylolysis with pedicle screw-laminar hook system can shorten length of operation,decrease blood loss, preserve more posterior structures of spine and avoid iatrogenic instability of spine. The postoperative immediate stability of vertebral segment is acquired and the mobility of adjacent intervertebral discs is reserved. The screw-laminar hook system for the treatment of adolescent spondylolisthesis can get satisfactory clinical results.

Multi-level spondylolysis

The incidence of isthmic spondylolysis is approximately 3% to 6% in the general population. Spondylolytic defects involving multiple vertebral levels, on the other hand, are extremely rare. Only a handful of reports have examined the outcomes of surgical treatment of multi-level spondylolysis. Here, we present one case of bilateral pars defects at L3, L4, and L5. The patient, a 46-year-old female, presented with lower back pain radiating into the left lower extremity. Radiographs and CT scans of the lumbar spine revealed bilateral pars defects at L3-L5. The patient underwent lumbar discectomy and interbody fusion of L4-S1 as well as direct repair of the pars defect at L3. There were no postoperative complications, and by seven months the patient had improved clinically. While previous reports describe the use of either direct repair or fusion in the treatment of spondylolysis, we are unaware of reports describing the use of both techniques at adjacent levels.

[Assessment of surgical correction of parameters of the vertebral-motor segment in traumas and degenerative diseases of the vertebral column]

Retrospective clinico-radial data obtained in 163 patients were compared with traumas and degenerative diseases of the vertebral column of those who were treated by decompressive and decompressive-stabilizing interventions. Characteristic alterations were determined such as considerably decreased area of the spinal canal (in 44.2% of the patients), intervertebral foramen (in 57.7%) and the volume of intervertebral canal (in 66.3%), which allowed specification of the character and volume of the operative interventions and objective assessment of adequacy of surgical correction.

Causes of radiculopathy in young athletes with spondylolysis

BACKGROUND

The main clinical symptom of lumbar spondylolysis is lower back pain. Radiculopathy rarely occurs without vertebral slippage. Hypothesis Spondylolysis in young athletes can cause lumbar radiculopathy.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Ten patients (7 males and 3 females) were included in this study. The age of the patients ranged from 12 to 27 years. We employed plain radiography, computed tomography, magnetic resonance imaging, and selective radiculography if needed.

RESULTS

The pathomechanism was classified into nonspondylolytic radiculopathy (3 cases) and spondylolytic radiculopathy (7 cases). In the nonspondylolytic group, 1 patient had a juxta-facet cyst at L4-5 and 2 patients had a herniated nucleus pulposus. In the other group, spondylolytic-related factors caused radiculopathy, and spondylolysis was in the early or progressive stage in all 7 patients. Radiologic findings indicated that radiculopathy was caused by extraosseous hematoma or edema in the vicinity of the fracture site. The radiculopathy disappeared within a month of nonoperative management, and radiologic abnormalities disappeared 3 to 6 months later.

CONCLUSION

Radiculopathy can occur together with lumbar spondylolysis without slippage in young athletes. We propose extra-osseous hematoma or edema at the site of spondylolysis as the unique pathomechanism causing radiculopathy in young athletes. Radiculopathy is rare in athletes with spondylolysis. Magnetic resonance imaging is a useful tool to clarify the pathologic changes that induce the radiculopathy for both spondylolytic and nonspondylolytic factors.

Presence of NGF and its receptor TrkA in degenerative lumbar facet joint specimens

In a preliminary study, the recurrent presence of nervous terminations was demonstrated with optical microscopy in several slides of degenerative lumbar facet joints and surrounding soft tissues. The purpose of this study was to prove the presence of NGF (nerve growth factor) and its receptor TrkA (tyrosine kinase receptor) with immunofluorescence. The peri/articular tissues were harvested from the lumbar facet joints of ten patients surgically treated for degenerative diseases. There were seven females (one bilateral) and two males whose mean age at surgery was 72 years (range, 67-80 years). The affected levels were L3-L4 in two cases and L4-L5 in seven cases (one bilateral). All specimens were fixed in formalin, dehydrated and enclosed in paraffin. From each specimen, four slides were obtained. Two slides were employed for the search of NGF: one was treated with specific antibodies and marked with FITC (fluorescein isothiocyanate conjugated), and the second slide was for control purposes. It was exposed to FITC, but without prior exposure to the specific antibody. The same procedure was repeated to obtain on two more slides, to repeat the search for Trka with specific antibodies. All the slides were finally studied on a fluoromicroscope. The analysis of these specimens revealed the presence of the neurotrophin (NGF) and its own receptor (TrkA) in all cases: the immunohistochemical reaction between the specimens and the specific antibodies marked with FITC was seen under fluoromicroscopy, but in none of the control cases treated with FITC only. NGF is released by mastocytes, fibroblasts and other cell types involved in the inflammatory processes. The level of peripheral NGF is increased in inflammatory processes, while the administration of exogenous NGF has a hyperalgesic effect on rats and produces muscular pain in humans. Furthermore, NGF produces hypersensitization to heat stimulation in humans and mammals in general. There is considerable evidence showing that the system constituted by the NGF and its high-affinity receptor TrkA plays a fundamental role in the molecular processes underlying the main forms of "persistent" pain. This indicates a possible therapeutic area for the antibodies that could block the NGF/TrkA system, in order to modulate the frequency and the duration of the action potential of nociceptive neurons during chronic inflammation. This study demonstrated the presence of NGF and TrkA in specimens collected from degenerative facet joints, suggesting that specific molecules could be used in order to modulate chronic pain in patients with degenerative lumbar spine.

Diaphanospondylodysostosis: six new cases and exclusion of the candidate genes, PAX1 and MEOX1

We report on six cases from four families with the newly described skeletal disorder diaphanospondylodysostosis (DSD). The characteristic radiographic findings included abnormal ossification of vertebral bodies, posterior rib gaps, missing ribs, and a downward tilt of the pubic rami, but normal long bones. The typical facial features of DSD cases were ocular hypertelorism, a short nose, depressed nasal bridge, and low set ears. Other distinctive findings included a short neck with bell-shaped thorax, and nephroblastomatosis. A history of consanguinity and affected siblings with unaffected parents supports autosomal recessive inheritance. Skeletal histology showed incomplete ossification of the ribs, vertebral bodies, and sacrum as well as incomplete formation of intervertebral discs. The posterior ribs were comprised of bone with intervening cartilage interrupted by dense fibrous tissue and skeletal muscle fascicles. These findings suggest abnormal development and differentiation of the paraxial mesoderm. Because of phenotypic similarities of DSD to Pax1 and Meox1 deficient mice, we sequenced genomic DNA from three unrelated DSD cases. No mutations were identified in the PAX1 and MEOX1 exons or flanking intronic sequences, excluding them as likely causative genes.

Repair of spondylolytic defect with a cable screw reconstruction

We present the clinical and radiological results of surgical repair for refractory spondylolysis in 20 patients at a minimum follow-up of 2 years. Seventeen of them were reassessed after 5 years. The Oswestry scores revealed good to excellent results in 90% (18/20 patients), indicating a good outcome with surgical repair using two techniques: the Scott procedure or pedicle screw and wire technique. Radiological pseudarthosis was 10%, which was quite consistent with reported series. CT scanning of the 14 patients after a mean of 13 months revealed complete healing of the fracture in 7 patients, partial in 2 and frank non-union in 5. Overall, CT examination with reversed gantry showed only 7/14 (50%) healing, indicating that radiological healing on plain X-ray is not always suggestive of complete bony healing. However, CT healing is not a sine qua non of good to excellent clinical outcome.

Spondylolysis

Low back pain, specifically "spondylo" conditions, has traditionally been misunderstood and often times ill-treated. A thorough understanding of the function of pars interarticularis and its relationship to the entire vertebral unit and low back health are essential for successful treatment and rehabilitation outcomes. Lifestyle awareness and controlled progression through the inflammation, stabilization, strength, and functional rehabilitation phases provide primary guidance for patients. In addition, a broad spectrum of pharmacological, psychological, therapeutic modality, and newer surgical techniques must be considered in the overall treatment plan. Having a strong understanding of the anatomy, biomechanics, treatment, and rehabilitation of this condition, will help the allied healthcare provider better meet the individualized needs of spondylolysis patients.

Perfusion-weighted magnetic resonance imaging of the spinal cord in cervical spondylotic myelopathy

Principles of echo shifting with a train of observations was used to perform magnetic susceptibility-weighted magnetic resonance imaging with bolus-tracking in 14 patients with spondylotic myelopathy to assess changes in perfusion parameters of the spinal cord before and after decompression surgery for cervical spondylotic myelopathy. The mean transit time (MTT), bolus arrival time (T0), and time to peak (TTP) were obtained from regions of interest (ROIs) and assessed as the ratio between the spinal cord and the pons (MTT index = MTT(ROI)/MTT(pons), T0 index = T0(ROI)/T0(pons), TTP index = TTP(ROI)/TTP(pons)). The patients were divided into two groups according to percentage improvement on the Neurosurgical Cervical Spine Scale. The MTT index in patients with good recovery (> or =50%) was significantly reduced. The T0 index and TTP index showed no significant change in both groups. Reduction of MTT index may indicate improved perfusion of the spinal cord following surgery for cervical spondylotic myelopathy.

Biomechanical and clinical study on screw hook fixation after direct repair of lumbar spondylolysis

OBJECTIVE

To evaluate the biomechanical effect and clinical results of hook screw fixation after direct repair of lumbar spondylous defects in the pars interarticularis.

METHODS

L(2)-L(6) spines of 8 fresh-frozen and thawed calf cadavers were used for mechanical testing. Bilateral spondylous defects were created in the L(4)vertebra. The intervertebral rotation ranges between L(4) and L(5) were scanned and computerized in various states of motion, such as flexion/extension, lateral bending and torsional loadings applied on the intact spine and the spondylous spine when the spondylous spine was fixed with modified Scott's fixation, hook screw fixation and Buck's fixation sequentially and respectively. Between July 2002 and February 2004, 14 young male patients (aged 15-31 years) suffering from symptomatic lumbar spondylolysis were treated with TSRH hook screw fixation after direct repair of the defects. MacNab criteria were used to assess their pre-and post-operative status.

RESULTS

Each fixation technique could significantly increase the intervertebral rotational stiffness and made the stiffness return to nearly the intact level. Hook screw technique provided more rotational stability than the others. Hook screw and Buck's techniques provided more flexion/extension stability than modified Scott's technique. Neither complication nor instrumental failure was observed in this study. The mean follow-up period was 21 months. All the patients except one acquired union during the follow-up period. Thirteen patients had a "good" or "excellent" result according to MacNab criteria.

CONCLUSIONS

Hook screw fixation shows biomechanical advantages and is safe and effective for young patients with lumbar spondylolysis.

Bilateral C5 motor paralysis following anterior cervical surgery—a case report

Numerous authors have reported C5 root palsies following posterior cervical surgery, and several mechanisms of injury have been proposed. Similar deficits after anterior cervical procedures are considered to occur less commonly. We report on a 48-year-old male who underwent multi-level anterior discectomy and fusion for cervical spondylotic myelopathy. Bilateral C5 nerve root deficits were noticed in the immediate postoperative period, and treated non-operatively. A postoperative magnetic resonance imaging (MRI) scan showed an increase in cervical lordosis accompanied by a posterior shifting of the spinal cord. Potential mechanisms of nerve root injury in this situation are discussed, and the literature on postoperative C5 root deficits is reviewed. The patient returned to his preoperative occupation as an operating room nurse 6 months following surgery, with complete neurologic recovery occurring over an 11-month period. C5 deficits following anterior cervical surgery occur more frequently than generally assumed. Improved lordosis and longitudinal lengthening of the cervical spinal column in multilevel anterior decompression and interbody fusion can paradoxically result in a traction injury to the spinal cord and C5 nerve roots.

Biomechanical and clinical evaluation of a novel technique for surgical repair of spondylolysis in adolescents

STUDY DESIGN

A biomechanical comparison of a novel spondylolysis repair technique method to established spondylolysis repair constructs accompanied by a case series of 5 adolescent patients with spondylolysis treated with this technique.

OBJECTIVES

To provide retrospective data on these patients treated with an intralaminar link construct, as well as present comparative biomechanical data on this construct and that of an intact spine, lytic spine, and known methods of repair.

SUMMARY OF BACKGROUND DATA

Spondylolysis is a unilateral or bilateral defect in the pars interarticularis, and most commonly occurs at L5 and less frequently at L4. Surgical treatment may be indicated in patients with persistent pain and impairment despite conservative treatment. Unlike posterolateral fusion, direct pars repairs may benefit adolescents by sparing motion segments.

METHODS

Biomechanical testing of 5 cadaver lumbar spines was completed to provide comparative biomechanical data on this intralaminar link construct, and that of an intact spine, destabilized spondylolytic spine, Scott wiring technique, pedicle screw-cable system, and the pedicle screw-rod-hook constructs. There were 5 adolescent patients with spondylolysis treated with multiaxial pedicle screws, with a modular linkage that passes beneath the spinous process of the same segment.

RESULTS

Biomechanical evaluation of the intralaminar link construct showed the least displacement (across pars defect) followed by the pedicle screw-rod-hook system, Scott wiring, and, finally, the pedicle screw-cable system. Interbody flexion and extension stiffness was highest for pedicle screw-rod-hook followed by normal, intralaminar link construct, Scott wiring, pedicle screw-cable system, and, finally, the destabilized spine. Interbody torsional stiffness was highest for pedicle screw-rod-hook followed by intralaminar link construct, normal, pedicle screw-cable system, Scott wiring, and lytic spine. Retrospective follow-up (average 4.6 years) of patients showed complete radiographic healing or pain relief in all 5 patients. There was 1 patient with solid healing of L3 spondylolysis who later had onset pain despite evidence of solid fusion on computerized tomographic images. In this patient, pain resolved after implant removal.

CONCLUSIONS

Biomechanical evaluation of the intralaminar link construct showed excellent stability of a spondylolytic defect in comparison to established methods. Clinical follow-up of this method reflects the results of biomechanical testing with excellent clinical results.

The femoro-sacral posterior angle: an anatomical sagittal pelvic parameter usable with dome-shaped sacrum

The sagittal pelvic morphology modulates the individual alignment of the spine. Anatomical angular parameters were described as follows: the "Pelvic Incidence" (PI) and the Jackson's angle "Pelvic Lordosis" (PR-S1). Significant chains of relationships were expressed connecting these angles with pelvic and spinal positional parameters. This allows an individual assessment of the harmony of the sagittal spinal balance. But in case of spondylolysis with high-grade listhesis, the upper plate of the sacrum shows a dome-shaped deformity. The previous anatomical parameters are therefore imprecise. Indeed, the anterior part of the sacrum being inaccurate, an exact assessment of these angles becomes impossible. Therefore, we propose a new angular parameter named "Femoro-Sacral Posterior Angle" (FSPA): the angle between the posterior wall of the first sacral vertebra, always well definite, and the line connecting the posterior part of the sacral plate to the femoral axis. The validation of this parameter was performed and compared with the classical published parameters. It showed good inter-observer reliability, even with dome-shaped sacral plate. In spite of lower correlation with the positional parameters than those observed with PI or PR-S1, the FSPA appeared to be reliable and precise for an exact evaluation of the sagittal spino-pelvic balance is case of spondylo-listhesis with dome-shaped sacral endplate.

Lumbar spinal disorders in patients with athetoid cerebral palsy: a clinical and biomechanical study

STUDY DESIGN

Radiologic study for patients with athetoid cerebral palsy (CP), and a biomechanical study using the finite-element model (FEM).

OBJECTIVES

To understand the lumbar disorders of athetoid CP patients and the etiology based on the results from the FEM study.

SUMMARY OF BACKGROUND DATA

Cervical spondylotic myelopathy is a well-identified spinal disorder associated with cerebral palsy, especially in athetoid type. One can rationalize that the athetoid involuntary trunk movement may induce stress-related lumbar disorders. Until now, very few investigations have been conducted on lumbar disorders that could occur in patients with CP.

METHODS

Sixty-one cases with athetoid cerebral palsy were clinically reviewed. Radiographs of the lumbar spine in 30 cases with low back pain were taken. From these radiographs, the incidence of lumbar spondylolysis and endplate lesion was analyzed. The biomechanical study was conducted using a three-dimensional FEM of the ligamentous lumbar spine. Axial compression of 400 N was applied to simulate preload on the spine during the standing position followed with 10.6 Nm moment to simulate extension and axial rotation. The combined motion of extension and axial rotation was also simulated. During supine position, pure extension and rotation were simulated, and no preload was applied. The von Mises stresses were computed at the pars interarticularis at the each level and compared for different motions.

RESULTS

Among the 61 patients, 41 complained of symptoms such as low back and leg pain. Thirty of these 41 patients gave their consents to undergo radiographic evaluation. Twenty-eight of the 30 patients (93.3%) showed stress-related disorders such as the spondylolysis and/or vertebral endplate lesions. Spondylolysis was found in 18 of the 30 patients (60.0%). Spondylolysis was observed at the multiple levels in 4 patients involving two levels in 2 cases and three levels in the other 2 cases. Vertebral endplate lesions (deformity) were seen in 26 (86.7%) of the 30 patients. Overall, the lesions (deformity) were found in 109 of 330 endplates (33.0%) out of all lumbar endplates in the 30 patients. The FEM based results showed that stresses at pars interarticularis of L5 were the highest of all levels in all loading modes, with or without preload. However, compared with the extension or axial rotation alone modes, the combined motion of extension and rotation showed higher stresses at the pars interarticularis.

CONCLUSIONS

The athetoid involuntary movements in CP patients may cause stress-related lumbar disorders. Especially, combined extension and rotation due to the involuntary trunk motion may contribute to the high incidence of spondylolysis.

Finite element analysis of the spondylolysis in lumbar spine

Spondylolysis is a fracture of the bone lamina in the pars interarticularis and has a high risk of developing spondylolisthesis, as well as traction on the spinal cord and nerve root, leading to spinal disorders or low back pain when the lumbar spine is subjected to high external forces. Previous studies mostly investigated the mechanical changes of the endplate in spondylolysis. However, little attention has been focused on the entire structural changes that occur in spondylolysis. Therefore, the purpose of this study was to evaluate the biomechanical changes in posterior ligaments, disc, endplate, and pars interarticularis between the intact lumbar spine and spondylolysis. A total of three finite element models, namely the intact L2-L4 lumbar spine, lumbar spine with unilateral pars defect and with bilateral pars defect were established using a software ANSYS 6.0. A loading of 10 N.m in flexion, extension, left torsion, right torsion, left lateral bending, and right lateral bending respectively were imposed on the superior surface of the L2 body. The bottom of the L4 vertebral body was completely constrained. The finite element models estimated that the lumbar spine with a unilateral pars defect was able to maintain spinal stability as the intact lumbar spine, but the contralateral pars experienced greater stress. For the lumbar spine with a bilateral pars defect, the rotation angle, the vertebral body displacement, the disc stress, and the endplate stress, was increased more when compared to the intact lumbar spine under extension or torsion.

Biomechanical comparison of lumbar spine with or without spina bifida occulta. A finite element analysis

STUDY DESIGN

Biomechanical study using finite element model (FEM) of lumbar spine.

OBJECTIVES

Very high coincidence of spina bifida occulta (SBO) has been reported more than in 60% of lumbar spondylolysis. The altered biomechanics due to SBO is one considerable factor for this coincidence. Thus, in this study, the biomechanical changes in the lumbar spine due to the presence of SBO were evaluated.

SETTING

United States of America (USA).

METHODS

An experimentally validated three-dimensional nonlinear FEM of the intact ligamentous L3-S1 segment was used and modified to simulate two kinds of SBO at L5. One model had SBO with no change in the length of the spinous process and the other had a small dysplastic spinous process. Von Mises stresses at pars interarticularis were analyzed in the six degrees of lumbar motion with 400 N axial compression, which simulates the standing position. The range of motion at L4/5 and L5/S1 were also calculated.

RESULTS

It was observed that the stresses in all the models were similar, and there was no change in the highest stress value when compared to the intact model. The range of motion was also similar in all the models. The lumbar kinematics of SBO was thus shown to be similar to the intact model.

CONCLUSION

SBO does not alter lumbar biomechanics with respect to stress and range of motion. The high coincidence of spondylolysis in spines with SBO may not be due to the mechanical factors.

An immunohistochemical study of the tissue bridging adult spondylolytic defects--the presence and significance of fibrocartilaginous entheses

Introduction Spondylolytic spondylolisthesis is an osseous discontinuity of the vertebral arch that predominantly affects the fifth lumbar vertebra. Biomechanical factors are closely related to the condition. An immunohistochemical investigation of lysis-zone tissue obtained from patients with isthmic spondylolisthesis was performed to determine the molecular composition of the lysis-zone tissue and enable interpretation of the mechanical demands to which the tissue is subject.

METHODS

During surgery, the tissue filling the spondylytic defects was removed from 13 patients. Twelve spondylolistheses were at the L5/S1 level with slippage being less than Meyerding grade II. Samples were methanol fixed, decalcified and cryosectioned. Sections were labelled with a panel of monoclonal antibodies directed against collagens, glycosaminoglycans and proteoglycans.

RESULTS

The lysis-zone tissue had an ordered collagenous structure with distinct fibrocartilaginous entheses at both ends. Typically, these had zones of calcified and uncalcified fibrocartilage labelling strongly for type II collagen and aggrecan. Labelling was also detected around bony spurs that extended from the enthesis into the lysis-zone. The entheses also labelled for types I, III and VI collagens, chondroitin four and six sulfate, keratan and dermatan sulfate, link protein, versican and tenascin.

CONCLUSIONS

Although the gap filled by the lysis tissue is a pathological feature, the tissue itself has hallmarks of a normal ligament-i.e. fibrocartilaginous entheses at either end of an ordered collagenous fibre structure. The fibrocartilage is believed to dissipate stress concentration at the hard/soft tissue boundary. The widespread occurrence of molecules typical of cartilage in the attachment of the lysis tissue, suggests that compressive and shear forces are present to which the enthesis is adapted, in addition to the expected tensile forces across the spondylolysis. Such a combination of tensile, shear and compressive forces must operate whenever there is any opening or closing of the spondylolytic gap.

Stretch-associated injury in cervical spondylotic myelopathy: new concept and review

The simple pathoanatomic concept that a narrowed spinal canal causes compression of the enclosed cord, leading to local tissue ischemia, injury, and neurological impairment, fails to explain the entire spectrum of clinical findings observed in cervical spondylotic myelopathy. A growing body of evidence indicates that spondylotic narrowing of the spinal canal and abnormal or excessive motion of the cervical spine results in increased strain and shear forces that cause localized axonal injury within the spinal cord. During normal motion, significant axial strains occur in the cervical spinal cord. At the cervicothoracic junction, where flexion is greatest, the spinal cord stretches 24% of its length. This causes local spinal cord strain. In the presence of pathological displacement, strain can exceed the material properties of the spinal cord and cause transient or permanent neurological injury. Stretch-associated injury is now widely accepted as the principal etiological factor of myelopathy in experimental models of neural injury, tethered cord syndrome, and diffuse axonal injury. Axonal injury reproducibly occurs at sites of maximal tensile loading in a well-defined sequence of intracellular events: myelin stretch injury, altered axolemmal permeability, calcium entry, cytoskeletal collapse, compaction of neurofilaments and microtubules, disruption of anterograde axonal transport, accumulation of organelles, axon retraction bulb formation, and secondary axotomy. Stretch and shear forces generated within the spinal cord seem to be important factors in the pathogenesis of cervical spondylotic myelopathy.

Is lumbar spondylosis a cause of urinary retention in elderly women?

OBJECTIVES

Lumbar spondylosis (LS) is a common spinal degenerative disorder which causes various types of lower urinary tract dysfunction (LUTD). However, it is not certain whether LS may cause urinary retention in elderly women.

METHODS

In a period covering the past 3 years, we retrospectively reviewed: a) urodynamic case records of women with urinary retention (post-void residuals, PVR > 100 ml), b) the records of women with LUTD due to LS (cauda equina syndrome and spinal canal narrowing by MRI), and c) uro-neurological features of women who belonged to both a) and b).

RESULTS

a) One-hundred women with a mean age of 58 years had urinary retention. The most common underlying disease was multiple system atrophy [19], followed by multiple sclerosis [13] and cervical/thoracic tumours [8]. LS was the fourth most common [5], with the highest age (71 years) of all diseases. b) Nineteen women with LUTD had LS (12, canal narrowing of 50-70%; 7 > 70 %), with a mean PVR volume of 60 ml. A fourth [5] of them had urinary retention, with severe spinal canal narrowing (all 5 > 70%). c) Thus, 5 women belonged to both a) and b). In 4 of these women, LUTD followed or occurred together with typical cauda equina syndrome symptoms such as sciatica and saddle anesthesia. However, one elderly woman presented with painless urinary retention, and absent ankle reflexes were the sole neurological abnormality. The urodynamic abnormalities underlying urinary retention included an underactive detrusor in all 5, bladder sensory impairment in 3, an unrelaxing sphincter in 2, a low compliance detrusor in one, neurogenic sphincter motor unit potentials in 2 of 4 studied, and cholinergic supersensitivity of the detrusor in one of 3 studied. Surgical decompression ameliorated urinary retention in 1 of 2 women who had surgery.

CONCLUSIONS

In our series, only 5 percent of the women with urinary retention had LS, but LS poses a potential risk for retention, particularly in elderly women with severe spinal canal narrowing. Preganglionic somato-autonomic dysfunctions underlie this condition. It may appear as the sole initial complaint in cases in which no other obvious neurological abnormalities are found.

Scoliosis research society outcome instrument in evaluation of long-term surgical results in spondylolysis and low-grade isthmic spondylolisthesis in young patients

STUDY DESIGN

A retrospective follow-up study of low-grade (slip < or = 50%) isthmic spondylolisthesis after posterior or posterolateral fusion in young patients.

OBJECTIVE

To evaluate the usefulness of the Scoliosis Research Society questionnaire and compare it with Oswestry Disability Index and radiographic parameters in patients with isthmic spondylolisthesis.

SUMMARY OF BACKGROUND DATA

A few studies have examined long-term patient outcome using validated questionnaires or compared it with radiographic parameters after surgery for isthmic spondylolisthesis in young patients. The Scoliosis Research Society questionnaire provides patient-oriented information on back pain, cosmetic aspects, patient satisfaction, and level of activity and might therefore be suitable for evaluation of surgical outcome after isthmic spondylolisthesis in young patients. However, there are no studies assessing the usefulness of the Scoliosis Research Society questionnaire for these patients.

METHODS

One hundred and eight patients treated at a mean (range) age of 15.9 (range, 8.1-19.8) years with posterior (n = 29) or posterolateral (n = 79) in situ fusion for isthmic spondylolisthesis participated in the present study. The follow-up rate was 83% after a mean of 20.8 (range, 15.1-25.9) years. The mean age at follow-up observation was 36.7 years. Radiographs were obtained before surgery, at 2-year follow-up observation, and at final follow-up review. The Scoliosis Research Society and Oswestry Disability Index questionnaires were completed, and a physical examination was performed at the final follow-up visit.

RESULTS

Nonunion after primary operation was found in 10 (34%) patients after posterior fusion and in 10 (13%) patients after posterolateral fusion (P = 0.0017). The mean (range) anterior slip was 25.2% (0-50%) before surgery and 24.2% (0-78%) at final follow-up observation. Lumbosacral kyphosis increased significantly during the follow-up period. The Scoliosis Research Society questionnaire yielded a total of 94.0 (range, 44-114) points. On the Scoliosis Research Society questionnaire, 14 (14%) patients reported back pain often or very often at rest. The Oswestry Disability Index scores averaged 8.2 (range, 0-68). There was a significant correlation between the Scoliosis Research Society total score and the Oswestry Disability Index. The percentage slip showed significant inverse correlations with the scores for appearance in clothes, attractiveness, and self image (Scoliosis Research Society questions 5, 14, and 15).

CONCLUSIONS

Long-term clinical and radiographic outcomes after posterolateral fusion of low-grade spondylolisthesis were satisfactory. Cosmetic aspects of this deformity should be included as one of the outcome measurements, since cosmetic questions on the Scoliosis Research Society questionnaire showed inverse correlations between the amount of slip at final follow-up observation. The Scoliosis Research Society questionnaire could be used as a primary patient-oriented outcome tool after back surgery in young patients.

[Spondylogenic hypertension of deep veins of the brain]

The cerebral deep veins hypertension criteria using bloodstream in large cerebral vein (Galen's vein) are worked up. An increase in venous pressure was proved to be connected with congenital and acquired pathology of cervical spine and craniovertebral isthmus. The new roentgenologic sign of pathology located in craniovertebral isthmus is determined. It is characterized by abnormal high front arc of the atlas, that hinders the outflow of venous blood from the cranial cavity.

Degenerative disc disease in childhood and adolescence

Degenerative disk disease (DDD) is a common cause of low back pain and leg pain in children and infants. DDD is often unrecognized and under-diagnosed. This paper presents six cases of DDD in children and discusses the clinical presentation and pathophysiology of DDD.

Effect of Postoperative Lumbar Sagittal Alignment on the Development of Adjacent Instability

OBJECTIVE

This study investigated the effect of postoperative lumbar sagittal alignment on the development of adjacent segment instability.

METHODS

The patients were retrospectively divided into two groups (hypolordotic and hyperlordotic) using the lumbar lordosis on lateral lumbosacral view. Diagnosis of adjacent segment instability depended on the dynamic lateral views of the lumbosacral spine.

RESULTS

Thirteen (21.7%) cases developed adjacent segment instability during the 6-year follow-up. The two groups had no significant difference in rates of developing adjacent segment instability.

CONCLUSION

Restoring the lordosis of the lumbar curve during one motion segment fusion does not prevent the development of adjacent instability.

A biomechanical study of lumbar spondylolysis based on a three-dimensional finite element method

Biomechanical analyses under compression only, and for a combination of flexion, extension, rotation, and lateral bending were performed to evaluate the stress of the interarticular portion of the lumbar vertebra using a nonlinear three-dimensional finite element method. A detailed three-dimensional L4-L5 motion segment model was developed that took into consideration the material nonlinearities of ligaments and annular fibers and the contact nonlinearities of facet joints. For a more accurate examination, the separation of cortical bone and cancellous bone for both posterior and anterior elements were also considered. The stress in the pars interarticularis was weakest under compression alone, but stronger under compression with lateral bending loading, with flexion, with rotation, and with extension. Under each loading condition, the region of the stress concentration was consistent with the separated region of the spondylolysis observed in clinical situations. Since the stress in the pars interarticularis was high under extension and rotation in particular, those loadings were suggested to be relatively high risk factors leading to spondylolysis.

Effects of lumbar spinal fusion on the other lumbar intervertebral levels (three-dimensional finite element analysis)

The risk of accelerating the degeneration of adjacent disc levels after lumbar spinal fusion is a controversial issue. A finite element model consisting of L1 to L5 lumbar spines was used to assess the effect on adjacent disc level after lumbar spinal fusion. We compared intact, L4/5 posterior interbody fusion (PLF), and L4/5 posterior lumbar interbody fusion (PLIF) models. The loading conditions applied were compressive force, compressive force plus flexion moment, and compressive force plus extension moment. Evaluations were made for von Mises stress on each vertebral end-plate, Tresca stress of all the annulus fibrosus, and Tresca stress of the annulus fibrosus from the posterior surface of the disc to the neural foramen. As the result, the von Mises stress adjacent to the fusion level was higher than the other nonfusion levels; it was higher under conditions of flexion moment loading plus compression loading [112% (2.59 PMa) in the PLF model and 117% (2.72 Mpa) in the PLIF model] than in the intact model. The Tresca stress of all the annulus fibrosus adjacent to the fusion level was higher than that on other nonfusion intervertebral levels; it was higher under conditions of flexion moment loading plus compression loading [127% (0.57 PMa) in the PLF model and 209% (0.89 Mpa) in the PLIF model] than in the intact model. The Tresca stress of the annulus fibrosus from the posterior surface of the disc to the neural foramen adjacent to the fusion level was higher than that on other nonfusion intervertebral levels; and it was higher under conditions of flexion moment loading plus compression loading [107% (1.48 PMa) in the PLF model and 112% (1.54 Mpa) in the PLIF model] than in the intact model. These findings demonstrate that with lumbar fusion, stresses on the vertebral end-plate and the annulus fibrosus were high adjacent to the fusion level; furthermore, stresses were higher in the PLIF model than in the PLF model. These results suggested that lumbar spinal fusion might bring with it a risk of damage to the annulus fibrosus and the vertebral end-plate adjacent to the fusion level.

Back injuries in young fast bowlers--a radiological investigation of the healing of spondylolysis and pedicle sclerosis

OBJECTIVE

To demonstrate the efficacy of various radiological diagnostic modalities in assessing lower back pain in young fast bowlers.

METHODS

Ten cricketers who presented to either a physiotherapist or a doctor with suspected spondylolysis underwent an X-ray, a single photon emission computed tomography (SPECT) bone scan and a computed tomography (CT) scan to assess the severity of the injury. Three and 12 months after the initial CT scan, second and third CT scans were performed in order to assess whether healing had taken place. After the initial radiological investigation the subjects diagnosed with spondylolysis or pedicle sclerosis underwent prescribed intervention and rehabilitation which included physiotherapy modalities, postural correction, and specific individually graded flexibility, stabilisation, strengthening and cardiovascular programmes.

RESULTS

Radiographs were normal in 8 subjects, while 2 had evidence of sclerosis. The isotope scan showed increased uptake in all of the subjects. The CT scans showed no fracture (N = 3), partial fractures (N = 3), complete fractures (N = 2) and old fractures bilaterally (N = 2). When the follow-up CT scan was carried out at 3 months, 1 of the subjects had developed a partial fracture of the left pars interarticularis on the inferior border, which showed complete union when CT scanned at 12 months. At 3 months the partial and complete fractures showed progressive healing in 2 subjects, with complete healing in all the other cases. Complete healing was achieved in all subjects at 12 months, with the exception of 1 subject who showed near-complete union, with a small area of fibrous union on the inferior border and 2 old bilateral fractures that remained un-united.

RESULTS

From the results it is evident that when a young fast bowler presents with backache after bowling, it would be appropriate to do an X-ray, a bone scan and a CT scan to make the diagnosis. Discontinuing the fast bowling and following an active rehabilitation programme should result in spontaneous resolution and healing of the fractures. If it is not detected early a fibrous or non-union fracture could result.

[Treatment of spondylolysis and spondylolisthesis with posterior STB thoracolumbar transpedicular screw-plate spine fixation system]

OBJECTIVE

To observe the clinical effect of a self-designed posterior STB thoracolumbar transpedicular screw-plate system in the treatment of spondylolysis and spondylolisthesis.

METHODS

This STB screw-plate system is developed with titanium alloy (TC4, Ti6Al4V). During December, 1999 and January, 2001, this system was applied in 51 cases, including lumbar spondylolysis and spondylolisthesis (36 cases), degenerative lumbar instability (15 cases). The patients were aged 22 - 78 years, mean age: 47.5 - years; among them there were 14 male cases, 37 female cases; There were 15 cases degenerative spondylolisthesis with grade I-II slip, 36 cases of spondylolysis and spondylolisthesis, including 34 cases with grade I-II slips and 2 cases with grade III slips; single level of 33 cases, two levels 3 cases. Decompression was performed for the 43 cases with interbody fusion using iliac crest or bilateral-lateral fusion using demineralized bone matrix and 8 cases were fixed with demineralized bone matrix fusion without decompression.

RESULTS

All the operations heeded about 60 - 120 minutes, and during the operations bleeding amounts were 200 - 500 ml. The cases completely recovered to work or normal action after 3 months of surgeries. 46 of all cases were achieved to satisfactorily reduction and clinical effect, 5 cases of grade II-III remained incomplete reduction (grade I slip).

CONCLUSION

This STB system has advantages of biomechanical stability and reduction capability and its effect in clinical application is undoubtedly positive.

The pathogenesis of slippage and deformity in the pediatric lumbar spine: a radiographic and histologic study using a new rat in vivo model

STUDY DESIGN

Rat lumbar spines with posterior destabilizing surgery were evaluated radiographically and histologically.

OBJECTIVES

To create an appropriate rat model showing the vertebral slippage and deformities frequently observed in pediatric patients with spondylolysis, and to clarify their pathogenesis.

SUMMARY OF BACKGROUND DATA

There are controversial hypotheses regarding the pathogenesis of slippage and deformities of the pediatric spine with pars defects. Furthermore, there is no appropriate animal model mimicking those conditions.

METHODS

After posterior destabilizing surgery, the lumbar spines of young (4-week-old) and adult (26-week-old) rats were radiographically examined at weekly intervals during 3 weeks, and histologically 3 weeks after the surgery.

RESULTS

Slippage occurred in the young rats, but not in the adult rats. In the young rats, 7.2% slippage was observed 1 week after the surgery, whereas the slippage in the adult rats was 0%. The difference in percentage of slippage between the two groups was significant (P < 0.05). Lumbar deformity also was seen in the young rats, but not in the adult rats. The lumbar index of L6, as an indicator of L6 rounding, was 91.7% immediately after surgery. It had decreased to 87.7, 84.6, and 74%, respectively, 1, 2, and 3 weeks after surgery. Histologic examination showed growth plate injury in the young group and pronounced disc degeneration in the adult group.

CONCLUSIONS

The young rat with posterior destabilizing surgery was an appropriate animal model, mimicking the slippage and deformities radiographically seen in pediatric patients with spondylolysis. The histologic examination indicated that vertebral growth plate impairment was the basic lesion causing such slippage and deformities in pediatric spines.

Spondylolysis of L2 in identical twins

OBJECTIVE

To discuss the presence of spondylolysis at L2 in identical twins.

CLINICAL FEATURES

Twin 61-year-old brothers reported insidious low back pain (LBP) of relatively recent onset. Both engaged in running as their main form of exercise. One had spondylolisthesis and history of significant traumatic incident; the other had no spondylolisthesis but a much more strenuous running regimen.

INTERVENTION AND OUTCOME

Both patients underwent a course of chiropractic treatment for mechanical LBP and reported a 50% overall improvement in symptoms.

CONCLUSIONS

Spondylolysis at L2 is uncommon, and although a familial component regarding weakness of the pars interarticularis has been demonstrated in the literature, spondylolysis at L2 in twins is extremely rare. Questions remain regarding the cause of spondylolisthesis in patients.

The biomechanical effects of spondylolysis and its treatment

STUDY DESIGN

Biomechanical analysis of the level above pars defects was performed using calf lumbar spines.

OBJECTIVES

To evaluate whether complete spondylolysis contributes to the pathology of the upper adjacent motion segment to the pars defect.

SUMMARY OF BACKGROUND DATA

It is well recognized that patients with spondylolysis show a higher incidence of spondylolisthesis or degenerative disc changes at the level of the pars defects. However, some authors have referred to the fact that disc damage may occur at the level above the defect and give rise to symptoms. However, no previous studies have been directed to the kinematic influence on the upper adjacent segment to pars defects.

METHODS

Nine fresh-frozen calf lumbar spines were used for this study. The bony defects were created on the L4 pars articularis bilaterally. Three linear extensometers and one specially designed angular extensometer were mounted across the L3-L4 and L4-L5 motion units. Nondestructive static loads, including axial compression, flexion-extension, and axial rotation, were applied on the specimens in four different conditions as follows: 1) intact spine; 2) bilateral pars defects on the L4 laminae; 3) pars defect repair with Buck technique; and 4) pedicle screw-rod fixation at L4-L5 after removal of the interarticular screws. Testing was performed on a material testing machine (MTS 858 Bionix test system, Minneapolis, MN), and load-displacement curves were recorded with the extensometers. Each test was performed for over five full sinusoidal loading cycles, and data from the fifth cycle were collected and analyzed.

RESULTS

After creating the pars interarticularis defects at L4, mobility at both the L3-L4 and L4-L5 motion units were increased in all loading conditions. The normalized range of motion (% ROM) as compared with the intact specimens showed that the pars defects increased the mobility at the upper adjacent level (L3-L4) to 106.4% in flexion-extension and to 120.1% in axial rotation; the differences were significant (P < 0.01). Consequently, the increased mobility was stabilized by applying Buck screws through the defects on both sides; however, the effect was not statistically significant. Furthermore, pedicle screw-rod fixation applied at the L4-L5 segment increased the intervertebral motion at the upper adjacent level, and % ROM in axial rotation was significantly increased to 119.2% of the intact spine (P < 0.05). Comparing the treatments' effects on the L3-L4 segment and that on L4-L5, the Buck screws restored the stability of both segments to the level of the intact spine, whereas the pedicle screw system limited the motion of L4-L5 motion and, on the contrary, increased the L3-L4 motion.

CONCLUSIONS

This biomechanical study exhibited that bilateral pars interarticularis defects increased the intervertebral mobility, not only at the involved level but also at the upper adjacent level to the lysis. The increased mobility at the upper segment was reduced by the Buck screw technique. However, this was increased again by the pedicle screw system applied on the involved segment. If clinically applicable, fixation of the pars defect alone appears to cause less adjacent level mechanical stress than pedicle screw-rod motion segment fixation.

Intra-individual variation in lumbar bone mineral density as a measure of spondylotic deformity in the elderly

In an attempt at quantitative assessment of spondylotic deformity, the intra-individual variation in L(1)-L(4) bone mineral density (BMD) was calculated, as the standard deviation (SD) and coefficient of variation (CV), obtained by dividing the SD by mean L(1)-L(4) BMD, in 463 subjects. The subjects ranged in age from their second to tenth decades. Dual-energy X-ray absorptiometry (DXA), using the Lunar DPX-L, was employed to assess the BMD. The SD of lumbar (L)BMD increased with advancing age in males, but not in females, whereas the CV of LBMD increased with age in both males and females, along with the radiographically assessed degree of severity of spondylosis deformans. Both the intra-individual SD and CV of L(1)-L(4) BMD showed a highly significant correlation with the radiological degree of severity of spondylosis deformans, and SD, but not CV, showed a strong dependence on the mean L(1)-L(4) BMD on a multiple regression test. Multiple regression test revealed no significant correlation between on body height, weight, fracture, and intra-individual variation in L(1)-L(4) projected area, reflecting compression fracture, one hand and SD or CV of L(1)-L(4) BMD on the other. Intra-individual variation in lumbar bone mineral density, expressed as a coefficient of variation, is suggested as an index of spondylotic deformity.

New strategies in the management of low back injuries in gymnasts

Low back pain is an extremely common complaint in competitive gymnasts, and these athletes are at risk for multiple potential structural injuries to the spine. Of particular concern among gymnasts is spondylolysis. Unfortunately, there are no published, controlled trials on the diagnosis or treatment of spondylolysis in adolescent athletes. However, based on the current literature, there would appear to be little role for the use of plain radiography in the diagnosis of symptomatic spondylolysis; nuclear imaging with single photon emission computed tomography (SPECT) appears to represent the best screening tool for diagnosis. Given the limited specificity of nuclear imaging in the spine, it is generally best to follow any positive study with a limited thin-cut computed tomography scan of the region of concern on the SPECT. Treatment should be based on the radiographic stage of the lesion. Relative rest is an essential component of care. Although the rehabilitation of gymnasts with lumbar injuries is poorly studied, the related literature would support incorporating the concepts of dynamic lumbar stabilization and sport-specific training into their rehabilitation programs.

Spondylolysis: returning the athlete to sports participation with brace treatment

Between 1988 and 1995, 73 adolescent athletes treated with the Boston Overlap Brace for spondylolysis were reviewed to evaluate improvement in pain score and activity level. A favorable clinical outcome was achieved in 80%. Girls and boys who participated in high-risk sports were five times more likely to have an unfavorable clinical outcome than those who participated in low-risk sports (odds ratio = 5, 95% confidence interval = 2.4-7.5, P = .003). In addition, acute onset of pain and hamstring tightness were associated with a worse outcome. Athletes with symptomatic spondylolysis treated with an antilordotic brace can expect improvement in their clinical course and return to sports participation in 4-6 weeks.

Normal and spondylolytic pediatric spine movements with reference to instantaneous axis of rotation

STUDY DESIGN

A radiologic study of lumbar kinematics in the pediatric spine was conducted.

OBJECTIVES

To clarify the kinematic alteration in the pediatric spine with pars defects by measuring the location of the instantaneous axis of rotation.

SUMMARY OF BACKGROUND DATA

Vertebral slippage and deformities such as wedging of L5 are observed frequently in pediatric patients with spondylolysis. However, the kinematics of pediatric lumbar spine with pars defects has not yet been well documented.

METHODS

Radiographs of 70 pediatric patients (57 boys and 13 girls) with low back pain were examined. The control group (without spondylolysis) consisted of 22 patients (15 boys and 7 girls; mean age, 14.6 years; range, 10-18 years), and the lysis group (with spondylolysis at L5) consisted of 48 patients (42 boys and 6 girls; mean age, 14.5 years; range, 11-18 years). The lysis group was further divided into four subgroups according to the stage of defects and existence of slippage: Group 1 (early stage defect), Group 2 (progressive stage defect), Group 3 (terminal stage defect without slippage), and Group 4 (terminal stage defect with slippage of more than 5%; olisthesis). The instantaneous axis of rotation at L4-L5 and L5-S1 from the extended to the flexed position was measured on lateral dynamic radiograms taken in with the subject in the recumbent position. The relation between lumbar index and the site of instantaneous axis of rotation at L5-S1 also was analyzed.

RESULTS

The site of instantaneous axis of rotation at L5-S1 and L4-L5 in the control group was not located in the rotating cranial vertebra. In 1 of the 11 patients in the early-stage subgroup, the instantaneous axis of rotation at L5-S1 was found in the cranial vertebra. In 4 of the 11 patients in the progressive stage, 11 of the 16 patients in the terminal stage, and in 7 of the 10 patients in the olisthesis subgroup, the instantaneous axis of rotation was located in the cranial vertebra. Cranial deviation in the instantaneous axis of rotation was observed more frequently in the vertebra with severe deformity less than 80% of the lumbar index than in the vertebra with milder deformity.

CONCLUSIONS

The instantaneous axis of rotation deviated cranially as the stage of pars defects advanced, and as the wedge deformity increased. Kinematic alteration of the lumbar spine in pediatric patients with spondylolysis may affect chondrocytes of the endplate, perhaps contributing to the consequent spine deformities occurring secondarily to spondylolysis.

Slippage mechanism of pediatric spondylolysis: biomechanical study using immature calf spines

STUDY DESIGN

This study analyzed the skeletal-age-dependent strength of the lumbar growth plate to resist anterior shearing forces using the MTS system in the immature calf spine with pars defects.

OBJECTIVE

To clarify the pathomechanism of the skeletal-age-dependent incidence of slippage in pediatric patients with pars defects by comparing the strength of the lumbar growth plate among three skeletal age groups.

SUMMARY OF BACKGROUND DATA

Isthmic spondylolisthesis occurs and progresses more frequently during the growth period, whereas it is rare afterward. However, little evidence has been demonstrated to elucidate the etiology.

METHODS

For this study, 15 lumbar functional spine units were divided into three groups according to their skeletal ages. Five were from neonates (Group 1), five from calves approximately 2 months old (Group 2), and five from calves about 24 months old (Group 3). An anterior shearing force was applied to each specimen until failure, after bilateral pars defects were created. Failure load (newtons) and displacement at failure (millimeters) were calculated from the load-displacement curve. The site of failure was confirmed by plain radiograph.

RESULTS

All 15 functional spine units failed at the growth plate. The failure load was 242.79 +/- 46.05 N in Group 1, 986.40 +/- 124.16 N in Group 2, and 2024.54 +/- 245.53 N in Group 3. Statistically significant differences were found among the three groups (P < 0.05). The displacement at failure was 7.52 +/- 1.84 mm in Group 1, 11.10 +/- 2.30 mm in Group 2, and 8.15 +/- 2.66 mm in Group 3. There were no significant differences among the groups.

CONCLUSIONS

The results indicate that the strength of the growth plate, the weakest link in this model, against anterior shearing forces depends on the skeletal maturity, and that the biomechanical weakness of the growth plate plays an important role in the slippage mechanism.

The pathomechanism of spondylolytic spondylolisthesis in immature primate lumbar spines in vitro and finite element assessments

STUDY DESIGN

Immature Chacma baboon (Papio ursinus) spine specimens were used to determine load-displacement behavior as related to disc injury. This was accomplished through the application of A-P shear force until failure of FSUs with pars defects. Several finite element models (FEMs) of the FSU were developed to study the mechanism of slippage in immature baboon lumbar spines.

OBJECTIVES

The purpose was to show that spondylolisthesis (olisthesis) always occurs through the growth plate using a model similar to immature human lumbar spines. Using FEMs, the roles of facet orientation, pars interarticularis thickness, and a weak growth-plate in producing slippage were examined.

SUMMARY OF BACKGROUND DATA

Progression from spondylolysis (lysis) to olisthesis occurs, most often, during the adolescent growth spurt. The biomechanical literature dealing with the slippage mechanism in the immature lumbar spine does not provide a clear understanding and is sparse.

METHODS

Several groups of FSUs were subjected to A-P shear force until failure. The results provided displacement at failure as a function of disc injury and flexion-extension fatigue. A bilateral pars defect was created in each specimen prior to application of A-P shear force using an MTS machine. Failure sites were assessed radiographically and histologically. A nonlinear 3-D FEM of the intact L4-L5 was created from CT scans. The model was modified to predict the effects of a pars fracture, a thin pars, a weak growth plate, and facet orientation on the shear load through the growth plate and stresses in the pars.

RESULTS

Experimentally, failures always occurred through the growth-plate in the disc intact and disc-incised groups. In the intact FEM, the growth plate carried21% of the applied A-P shear force. The load increased when the facets were more sagittally oriented. The effect of thin pars and/or weaker growth plate was an increase in stresses in the pars. Changes in the load through the growth plate were minimal.

CONCLUSIONS

The weakest link in immature baboon lumbar functional spinal units (FSUs) with lysis during an A-P shear load was the growth plate, between the cartilaginous and osseous end plates. Surgeons may assess this lesion on MRI views, thereby predicting the possible development and preventing progression of olisthesis. Finite element model results predict that more sagittally orientated facets and/or a pars fracture are prerequisites for olisthesis to occur.

[Biomechanics in the pathogenesis of spondylosis and spondylolisthesis]

The etiology and predisposing factors of spondylolysis and spondylolisthesis, which are summarized in the first part of this article, have received considerable attention, but there biomechanics is little published. The goal of this article is to show a biomechanical model for the development of spondylolysis and spondylolisthesis. With mechanical equations it has been established, the pars interarticularis and the ligaments resist together the tensile and shear force, the bending moment if the pars interarticularis is uncracked. If the tensile stress in the pars interarticularis reaches its strength, crack occurs and the spondylolysis is developed. The cracked pars interarticularis is no longer capable of sustaining tension, the tensile force is transferred to the ligament. When the compressive strain of the pars interarticularis reaches its strain limit, the spondylolisthesis does not develop, because the vertebra can not slip with the unbroken ligaments. If the loading on the pars interarticularis would be decreasing, the cracks close and the pars interarticularis can ossify. If the tensile stress in the ligament reaches its strength and the ligament breaks, the pars interarticularis cracks through, the vertebra slips and the spondylolisthesis develops. In the last part of the article the methods of the conservative and operative treating are summarized.

Global spinal motion in subjects with lumbar spondylolysis and spondylolisthesis: does the grade or type of slip affect global spinal motion?

STUDY DESIGN

This was a prospective pilot study to investigate the global motion characteristics of the spondylolysis and spondylolisthesis populations.

OBJECTIVES

The aim of this study is to determine the influence of a spondylolisthesis or a spondylolysis on global spinal motion and to establish whether this is dependent on the cause of the slip or the degree/grade of the slip.

SUMMARY OF BACKGROUND DATA

The condition of spondylolisthesis has been extensively discussed in the literature with respect to its etiology and management. However, the mechanics and movement of the spine in relation to pathology and the effect of this condition on function have received scant attention.

METHODS

The motion of the lumbar spine was investigated in 31 patients (19 men, 12 women, mean age 47.7 +/- 17.8 years) who were diagnosed as having either a lumbar spondylolysis or a spondylolisthesis. These patients were compared with a preexisting database of 203 normal subjects (100 men, 103 women, mean age 39.8 +/- 13.4 years). Patients were graded according to the type of spondylolisthesis or spondylolysis they had, and the extent of slip was rated using Meyerding's classification (1932) and measured directly using methods of Boxall et al (1979) and Wiltse et al (1983).

RESULTS

Direct measurements of the extent of slip using Boxall et al (1979) and Wiltse et al (1983) methods were found to have no significant correlation with the resultant range of motion (ROM) or the speed of movement. This study suggests that motion parameters are influenced by the grade of slip in patients with spondylolisthesis, and the type of spondylolisthesis i.e., whether isthmic or degenerative. In the A-P flexion-extension plane, the results indicate that subjects with a defect only, i.e., a spondylolysis, and thus no slip present with a spinal hypermobility (P < 0.01). Subjects with an isthmic slip tend to be either slightly hypermobile or within the anticipated range of motion, whereas those subjects with a degenerative slip tend to be hypomobile (P < 0.05). Movements into lateral flexion were restricted in both the isthmic and degenerative spondylolisthesis patients, whereas rotation was only influenced by the level at which the defect occurred. In terms of degree of displacement, in higher grades of displacement, there was a trend towards hypermobility.

CONCLUSIONS

The findings of this study suggest that the grade and type of spondylolisthesis do influence global motion parameters. This information may be useful in the clinical assessment of this patient group.

Spondylolysis: a critical review

AIM

To provide an understanding of the current concepts in the natural history, pathophysiology, diagnosis, and treatment of spondylolysis based on the available medical literature.

METHODS

Articles were selected for review by the following methods: (a) MEDLINE searches with review of abstracts to select relevant articles; (b) review of multiple textbooks considered likely to contain information on spondylolysis; (c) review of references in articles identified by (a) and (b). Over 125 articles were ultimately reviewed fully. Publications were selected for inclusion in this article on the basis of perceived scientific and historical merit, particularly as thought to be relevant to achieving the stated purpose of this review. As no controlled clinical trials were identified, this could not be used as an inclusion criterion.

CONCLUSIONS

Isthmic spondylolysis is considered to represent a fatigue fracture of the pars interarticularis of the neural arch. There is a relatively high incidence of radiographically identified spondylolysis in the general population, but the vast majority of these lesions probably occur without associated symptoms. Symptomatic pars lesions appear to be particularly a clinical problem in adolescents, especially adolescent athletes. The optimal diagnostic and treatment algorithms are not well identified in the current literature. Multiple imaging studies may have a role in the diagnosis of a pars lesion, and treatment seems likely to require at least relative rest and physical rehabilitation with consideration of bracing or, rarely, surgical intervention depending on the clinical context.

Back injuries and the fast bowler in cricket

Here, I review research that has investigated the aetiology of injuries experienced by adolescent and adult fast bowlers. Mechanical factors play an important role in the aetiology of degenerative processes and injuries to the lumbar spine. This is particularly so in fast bowling, where a player must absorb vertical and horizontal components of the ground reaction force that are approximately five and two times body weight at front-foot and rear-foot impact, respectively. Attenuated forces are transmitted to the spine through the lower limb, while additional forces at the lumbo-sacral junction are caused by trunk hyperextension, lateral flexion and twisting during the delivery stride. Fast bowlers are classified as side-on, front-on or mixed. The mixed action is categorized by the lower body configuration of the front-on action and the upper body configuration of the side-on technique. This upper body configuration is produced by counter-rotation away from the batsman in the transverse plane about the longitudinal axis of the body of a line through the two shoulders. Counter-rotations of 12-40 degrees during a delivery stride have predicted an increased incidence of lumbar spondylolysis, disc abnormality and muscle injury in fast bowlers. During the delivery stride, the mixed bowling action also shows: more lateral flexion and hyperextension of the lumbar spine at front-foot impact, and a greater range of motion of the trunk over the delivery stride when compared with the side-on and front-on techniques. The pars interarticularis of each vertebra is vulnerable to injury if repetitive flexion, rotation and hyperextension are present in the activity. Fast bowlers should reduce shoulder counter-rotation during the delivery stride to reduce the incidence of back injuries. When a player is required to bowl for extended periods irrespective of technique, overuse is also related to an increased incidence of back injuries and must be avoided.

Spondylolysis

Spondylolysis is a relatively common incidental radiographic finding that, most frequently, is asymptomatic. Isthmic spondylolysis with a lesion in the pars interarticularis may be a significant cause of pain in a given individual, particularly in adolescent athletes involved in sports with repetitive spinal motions. The pars lesion likely represents a stress fracture of the bone caused by the cumulative effect of repetitive stress imposed by physical activity. The lesion frequently presents as focal LBP and can often be identified on plain radiography. Advanced imaging with SPECT, CT, and MR imaging may be needed to ascertain the acuity of the lesion, assist in identifying a particular pars lesion as potentially symptomatic, and to exclude other spinal pathology that may be present. Conservative treatment is usually successful in controlling symptoms and restoring function; only a small percentage of patients require surgical intervention for pain or progressive spondylolisthesis. Based on current evidence, treatment requires activity restriction (i.e., temporary discontinuation of the aggravating sport or activity) and may require bracing to achieve treatment goals, although healing, pain relief or both may occur without brace application. A full understanding of spinal biomechanics and pathophysiology, the role of diagnostic imaging, and treatment options is needed to care for these patients.

Biomechanical functions of the iliolumbar ligament in L5 spondylolysis

Abiomechanical study of the functions of the iliolumbar ligament in L5 spondylolysis was performed. Five fresh cadaveric specimens were used. The bilateral ilia and sacrum were fixed. Four kinds of pure moments (10 Nm) were applied to the specimens at the top (L4) vertebra: flexion, extension, and right and left axial rotations. The three-dimensional position of the L5 vertebra was measured after serial transections in: (1) the intact condition; (2) bilateral pars interarticulares of L5 transected; (3) anterior bands of the iliolumbar ligaments transected; and (4) posterior bands of the iliolumbar ligaments transected. In L5 spondylolysis, flexion and axial rotation of L5 on S1 are significantly regulated by the anterior and posterior bands of the iliolumbar ligaments (especially by the posterior bands of the ligaments). The integrity of the ligament may determine the stability of the lumbosacral junction and the amount of forward slipping of the L5 vertebra.

Is there increased intervertebral mobility in isthmic adult spondylolisthesis? A matched comparative study using roentgen stereophotogrammetry

STUDY DESIGN

By roentgen stereophotogrammetric technique, the intervertebral mobility of the spondylolytic segment in eight patients was measured and compared with the mobility of eight nonspondylolytic patients matched according to sex, afflicted segment, and grade of disc degeneration.

OBJECTIVES

To compare the intervertebral mobility of a spondylolytic segment with the mobility of a segment without spondylolysis in adult patients with back pain.

SUMMARY OF BACKGROUND DATA

Evidenced by the resulting olisthetic deformity and supported by the outcome from prior investigations, spondylolysis is assumed to induce spinal segmental instability/hypermobility.

METHODS

After percutaneous application of tantalum indicators for roentgen stereophotogrammetric technique, the intervertebral translations of the spondylolytic fifth lumbar vertebra were measured in eight adult patients with low back pain and low-grade olisthesis. Eight other patients without spondylolysis but with low back pain presumably on degenerative basis were chosen for comparison and had an identical measuring procedure using roentgen stereophotogrammetric technique. The two groups were matched in pairs according to sex, afflicted segment, and grade of disc degeneration.

RESULTS

No significant difference was registered considering the intervertebral mobility for matched pairs in the two groups neither along the sagittal nor the vertical axis. The transverse translations were mostly negligible in both groups.

CONCLUSION

The spondylolytic defect in pars interarticularis does not cause permanent instability/hypermobility detectable in the adult patient with low back pain and low-grade olisthesis.