RESUMEN
We investigated the incidence of anomalies in the vertebral arteries and Circle of Willis with three-dimensional CT angiography in 55 consecutive patients who had undergone an instrumented posterior fusion of the cervical spine. We recorded any peri-operative and post-operative complications. The frequency of congenital anomalies was 30.9%, abnormal vertebral artery blood flow was 58.2% and vertebral artery dominance 40%. The posterior communicating artery was occluded on one side in 41.8% of patients and bilaterally in 38.2%. Variations in the vertebral arteries and Circle of Willis were not significantly related to the presence or absence of posterior communicating arteries. Importantly, 18.2% of patients showed characteristic variations in the Circle of Willis with unilateral vertebral artery stenosis or a dominant vertebral artery, indicating that injury may cause lethal complications. One patient had post-operative cerebellar symptoms due to intra-operative injury of the vertebral artery, and one underwent a different surgical procedure because of insufficient collateral circulation. Pre-operative assessment of the vertebral arteries and Circle of Willis is essential if a posterior spinal fusion with instrumentation is to be carried out safely.
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Vértebras Cervicales/cirugía , Círculo Arterial Cerebral/anomalías , Fusión Vertebral/efectos adversos , Arteria Vertebral/anomalías , Anomalías Múltiples/cirugía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Articulación Atlantoaxoidea/anomalías , Vértebras Cervicales/anomalías , Círculo Arterial Cerebral/diagnóstico por imagen , Circulación Colateral/fisiología , Femenino , Humanos , Inestabilidad de la Articulación/diagnóstico por imagen , Inestabilidad de la Articulación/cirugía , Masculino , Persona de Mediana Edad , Cuidados Preoperatorios/métodos , Factores de Riesgo , Fusión Vertebral/instrumentación , Tomografía Computarizada por Rayos X , Arteria Vertebral/diagnóstico por imagen , Arteria Vertebral/lesiones , Insuficiencia Vertebrobasilar/complicaciones , Adulto JovenRESUMEN
The authors report the cases of 3 patients with tuberculous spondylodiscitis. All patients suffered from severe back or low back pain. Posterolateral endoscopic debridement and irrigation were performed followed by retention of a drainage tube at the affected sites. Additional puncture and drainage were conducted at the same time when extensive cold abscesses were identified around the paravertebral muscle. All patients experienced immediate pain relief postoperatively. This technique is effective for rapid pain relief and in obtaining neurological resolution for patients in the early stages of tuberculous spondylodiscitis and may also be a good method for preventing further vertebral collapse and kyphotic spinal deformity such as Gibbus vertebrae.
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Discitis/microbiología , Discitis/cirugía , Procedimientos Quirúrgicos Mínimamente Invasivos/métodos , Tuberculosis/complicaciones , Adulto , Discitis/diagnóstico , Femenino , Humanos , Disco Intervertebral/microbiología , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Mycobacterium/aislamiento & purificaciónRESUMEN
STUDY DESIGN: A biomechanical study was designed to assess the bone-screw interface fixation strength among five anterior spinal instrumentation systems for scoliosis before and after a fatigue simulation. OBJECTIVES: The objectives of the current study were twofold: 1) evaluate the static (initial) strength at the bone-screw interface and 2) evaluate dynamic (post fatigue) strength of the bone-screw interface after a fatigue simulation to investigate a possible mechanism for postoperative loss of correction. SUMMARY OF BACKGROUND DATA: Although the recent advancement of anterior instrumentation for scoliosis has permitted shorter fusion segments and improved surgical correction, the loss of correction over the instrumented segments still has been reported in one-rod systems. Little is known about the mechanism for loss of correction. METHODS: Twenty-five fresh-frozen calf spines (T6-L6) were used. A total of five instrumentation systems included the following: Anterior ISOLA (ISOLA), Bad Wildungen Metz (BWM), Texas Scottish Rite Hospital system (TSRH), Cotrel-Dubousset Hoph (CDH), and Kaneda Anterior Scoliosis System (KASS). Screw pullout and rotational tests in the sagittal plane using a single vertebra were performed to investigate bone-screw interface fixation strength before and after a fatigue simulation. To simulate cyclic loading that the spine could undergo in vivo, a fatigue simulation using compressive-flexion loading up to 24,000 cycles was carried out. RESULTS: Mean maximum tensile pullout force decreased in the following order: KASS > CDH > BWM > TSRH > ISOLA (F = 29.91, P < 0.0001). KASS blunt tip screw was 26% stronger in pullout force than KASS sharp tip screw (P < 0.05). The one-rod system demonstrated a positive correlation between pullout force and both bone mineral density and screw insertional torque. For fatigue analysis the rotational strength at the most cephalad and caudal segments significantly decreased after a fatigue simulation in the one-rod system (P < 0.05). The two-rod system showed no significant decrease after a fatigue simulation. CONCLUSIONS: Simulating the cyclic loading to the construct, screw loosening at the bone-screw interface was produced in the one-rod system. This screw loosening may elucidate one mechanism for loss of correction in the one-rod system. The two-rod system may have the potential to minimize the risk of loss of correction.
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Tornillos Óseos , Escoliosis/cirugía , Fusión Vertebral/instrumentación , Análisis de Varianza , Animales , Fenómenos Biomecánicos , Bovinos , Falla de Equipo , Técnicas In Vitro , Estrés Mecánico , Resistencia a la Tracción , Vértebras Torácicas/cirugíaRESUMEN
STUDY DESIGN: The inter- and intraobserver reliabilities of an assessment scale for cervical compression myelopathy were examined statistically. This scoring system consists of seven categories: motor function of fingers, shoulder and elbow, and lower extremity; sensory function of upper extremity, trunk and lower extremity; and function of the bladder. It evaluates the severity of myelopathy by allocating points based on degree of dysfunction in each category. OBJECTIVES: To determine the inter- and intraobserver reliabilities of the revised scoring system (17 - 2 points) for cervical compression myelopathy proposed by the Japanese Orthopedic Association. SUMMARY OF BACKGROUND DATA: Several scales to assess clinical outcome from treatment of cervical compression myelopathy have been proposed. Most of these scales include items evaluated by observers. However, no system, including the Japanese Orthopedic Association scoring system, has yet been validated in terms of interobserver reliability. METHODS: From five different university hospitals, 10 spine surgery specialists, 10 orthopedic surgeons who had just passed the board examination of the Japanese Orthopedic Association, and 13 residents in the first or second year of orthopedic residency programs were chosen. The participants in this study were 29 patients with myelopathy secondary to ossification of the posterior longitudinal ligament selected from five participating university hospitals. Several surgeons interviewed each patient twice at intervals of 1 to 6 weeks. Inter- and intraobserver reliabilities of the total score for all categories were evaluated by the intraclass correlation coefficient. The extension of the kappa coefficient of Kraemer also was calculated for each category to assess reliability of multivariate categorical data. RESULTS: The interobserver reliability of the total score for the first interview (intraclass correlation coefficient = 0.813) and the intra- and interobserver reliabilities of the total score (intraclass correlation coefficient = 0.826) were high. The level of experience and the hospital slightly affected the reliability of the Japanese Orthopedic Association scoring system. The kappa values for intraobserver data generally were high in each category, whereas the kappa values for interobserver data were relatively low for the categories of shoulder-elbow motor function and lower extremity sensory function. CONCLUSIONS: The inter- and intraobserver reliabilities of the Japanese Orthopedic Association scoring system for cervical myelopathy were high, suggesting that this system is useful for assessment of cervical myelopathy in comparative studies of treatment.
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Ortopedia/métodos , Índice de Severidad de la Enfermedad , Compresión de la Médula Espinal/diagnóstico , Actividades Cotidianas , Vértebras Cervicales , Hospitales Universitarios , Humanos , Japón , Variaciones Dependientes del Observador , Osificación del Ligamento Longitudinal Posterior/complicaciones , Osificación del Ligamento Longitudinal Posterior/fisiopatología , Reproducibilidad de los Resultados , Sociedades Médicas , Compresión de la Médula Espinal/clasificación , Compresión de la Médula Espinal/etiología , Compresión de la Médula Espinal/fisiopatologíaRESUMEN
STUDY DESIGN: We have developed a new artificial intervertebral disc consisting of triaxial three-dimensional fabric for the sheep lumbar spine. To clarify the characteristics of the new implant, a series of biomechanical tests and morphologic evaluations were conducted. OBJECTIVES: To investigate the static, viscoelastic, and fatigue properties of the three-dimensional fabric disc in comparison with natural sheep disc and to evaluate their biomechanical and morphologic alteration in vivo. SUMMARY OF BACKGROUND DATA: In its human dimensions the three-dimensional fabric disc revealed mechanical properties similar to a natural human disc. METHODS: The disc-body units from sheep spine and the sheep three-dimensional fabric discs underwent tensile-compressive (200 N), torsional (5 Nm), and creep-recovery tests (30 minutes-30 minutes, 200 N). After fatigue loading (2 million, compressive 200 N) the biomechanical changes and the debris were investigated. For in vivo evaluation after placing in the sheep psoas muscles for 6 months, the surface of the three-dimensional fabric disc was evaluated using macroscopy and scanning electron microscopy, followed by previous biomechanical tests. RESULTS: The behavior of the sheep three-dimensional fabric disc was similar to that of natural sheep disc in tensile-compressive and creep-recovery tests. In torsional testing the behavior of natural sheep disc was more rigid than that of the sheep three-dimensional fabric disc. After fatigue loading there was no biomechanical change and no debris detected. Six months after surgery no morphologic deterioration was observed nor were there changes in biomechanical parameters. CONCLUSIONS: The sheep three-dimensional fabric disc exhibited biomechanical and morphologic biostability, appropriate viscoelasticity, and excellent fatigue properties. The three-dimensional fabric disc has a potential for clinical application of human intervertebral disc replacement.
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Materiales Biocompatibles , Disco Intervertebral/patología , Disco Intervertebral/fisiología , Vértebras Lumbares/cirugía , Falla de Prótesis , Animales , Fuerza Compresiva/fisiología , Femenino , Técnicas In Vitro , Disco Intervertebral/trasplante , Vértebras Lumbares/fisiología , Ensayo de Materiales , Modelos Animales , OvinosRESUMEN
STUDY DESIGN: A retrospective study of 12 patients with congenital kyphoscoliosis caused by a single hemivertebra who underwent one-stage posterior hemivertebra resection and correction by posterior segmental instrumentation. OBJECTIVES: To evaluate the surgical outcomes of 12 patients with hemivertebra treated by hemivertebra resection by single posterior approach and correction with segmental posterior instrumentation. SUMMARY OF BACKGROUND DATA: Congenital scoliosis caused by hemivertebra causes extremely severe curves in some patients. Posterior fusion or posterior and anterior hemi-epiphysiodesis is performed to prevent progression of the deformity. The results of these procedures have been variable and not promising, especially in an adolescent patient with fixed kyphoscoliotic deformity. Hemivertebra resection offers more certain results and better correction of the deformity. To date, hemivertebra resection is performed by anterior and posterior approaches either by one-stage or two-stage operation. Few reports have been published describing a procedure consisting of one-stage posterior hemivertebra resection and correction of the deformity by segmental posterior instrumentation. METHODS: A total of 12 patients with a single hemivertebra between the ages 8-24 years who underwent operative treatment were evaluated for a minimum of 2 years. All patients had a single nonincarcerated hemivertebra [T9 (1 patient), T10 (2), T11 (2), T12 (4), and L1 (3)]. After posterior hemivertebra resection, segmental posterior instrumentation was used for correction of the kyphoscoliotic deformity [CD (4 patients), Kaneda SR (2), and ISOLA (6)]. Radiographic evaluations were conducted on the preoperative, postoperative, and follow-up standing posteroanterior and lateral radiographs. RESULTS: All 12 patients had kyphoscoliotic deformity. Preoperative scoliosis averaging 49 degrees was corrected to 18 degrees (correction rate, 64%). Preoperative kyphosis of 40 degrees was corrected to 17 degrees of kyphosis. Trunk shift of 23 mm was improved to 3 mm. Correction loss was 2 degrees in the frontal plane and 3 degrees in the sagittal plane, and no patients showed more than 5 degrees of correction loss. No intraoperative complications were noted. Solid fusion was obtained in all patients, and no implant failure was verified at the final radiographic evaluations. CONCLUSIONS: This study indicated that correction of kyphoscoliosis caused by a single hemivertebra can be effectively conducted by one-stage posterior hemivertebra resection and correction using segmental posterior instrumentation. The operation was safe, and no associated adverse complications were noted. This procedure is best indicated for adolescent patients with a structural kyphoscoliotic deformity caused by a thoracic or thoracolumbar single hemivertebra.
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Fusión Vertebral/instrumentación , Columna Vertebral/anomalías , Columna Vertebral/cirugía , Adolescente , Adulto , Niño , Femenino , Estudios de Seguimiento , Humanos , Masculino , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
Although range of motion has been considered the best parameter to quantify atlantoaxial instability, no other kinematic parameters have been determined for dynamic quantification. The objectives of this study were to investigate the kinematics of the normal and pathologic atlantoaxial joints by cineradiography and to determine the in-vivo kinematic parameters, if any, for the quantification of atlantoaxial instability. Sagittal plane motion of the atlantoaxial joints was analyzed by cineradiography in 12 healthy volunteers and 15 patients with atlantoaxial subluxation. In both flexion and extension, C1-C2 sagittal rotation and C1 translation in the sagittal plane were measured continuously to determine the time-displacement curves for both parameters. All patients with atlantoaxial subluxation and seven of the volunteers had the sigmoid pattern in their time-displacement curves in sagittal rotation. In these cases, atlantoaxial motion showed different points of the onset of rapid increase in motion in their sigmoid curves between flexion and extension. The discrepancy between these points was more significant in the patients than in the volunteers. In most of the patients who had atlantoaxial instability, subluxation occurred when the atlantoaxial joints were still in a more extended position and they were reduced when they were still in more flexed position. The discrepancy showed characteristics similar to those of the neutral zone observed during in vitro investigations, suggesting that it becomes a good indicator of in vivo atlantoaxial instability.
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Articulación Atlantoaxoidea/fisiopatología , Cinerradiografía , Inestabilidad de la Articulación/diagnóstico por imagen , Inestabilidad de la Articulación/fisiopatología , Adulto , Fenómenos Biomecánicos , Humanos , Masculino , Movimiento , Rango del Movimiento ArticularRESUMEN
STUDY DESIGN: Sixteen patients with hemodialysis-associated cervical spine disorders underwent surgical treatment. After analysis of the surgical results, the optimum surgical procedures for these disorders were discussed. OBJECTIVE: To evaluate the surgical results of cervical spine disorders associated with long-term hemodialysis and to propose the optimum surgical procedures for successful outcomes. SUMMARY OF BACKGROUND DATA: There have been few reports regarding surgical results of hemodialysis-related cervical spine disorders. Surgical treatment for this disorder is still challenging. METHODS: Sixteen patients with hemodialysis-associated cervical spine disorders were treated surgically. Duration of hemodialysis ranged from 8 to 27 years (average, 17 years). Before surgery, 14 patients showed severe cervical myelopathy, and the other 2 had radiculopathy in the upper extremities. Ten patients with marked destructive changes underwent circumferential reconstructive surgery involving pedicle screw fixation, anterior strut bone grafting, and posterior and/or anterior decompression. Two patients with cervical radiculopathy underwent posterior nerve root decompression by foraminotomy and fusion by pedicle screw fixation or spinous process wiring. The remaining four patients without spinal instability underwent posterior decompression by open-door laminoplasty. RESULTS: Two patients died during follow-up. Follow-up periods in the surviving 14 patients ranged from 25 months to 92 months (average, 53 months). Marked neurologic recovery was obtained in all patients after surgery. Successful spinal fusion was obtained in all patients except one who underwent posterior fusion by spinous process wiring. Progressive destructive changes with significant instability at the adjacent mobile segments were observed in two patients who underwent circumferential fusion with a pedicle screw system more than 2 years after the initial surgery. CONCLUSIONS: The pedicle screw system achieved a high fusion rate in reconstructive surgery of cervical destructive spondyloarthropathy, even in the presence of severe bone fragility.
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Vértebras Cervicales/cirugía , Osteofitosis Vertebral/cirugía , Adulto , Anciano , Vértebras Cervicales/diagnóstico por imagen , Vértebras Cervicales/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dispositivos de Fijación Ortopédica , Radiografía , Diálisis Renal/efectos adversos , Insuficiencia Renal/terapia , Fusión Vertebral/instrumentación , Fusión Vertebral/métodos , Osteofitosis Vertebral/diagnóstico por imagen , Osteofitosis Vertebral/etiología , Resultado del TratamientoRESUMEN
OBJECT: Interbody fusion devices are rapidly gaining acceptance as a method of ensuring lumbar interbody arthrodesis. Although different types of devices have been developed, the comparative reconstruction stability remains controversial. It also remains unclear how different stress-shielded environments are created within the devices. Using a calf spine model, this study was designed to compare the construct stiffness afforded by 11 differently designed lumbar interbody fusion devices and to quantify their stress-shielding effects by measuring pressure within the devices. METHODS: Sixty-six lumbar specimens obtained from calves were subjected to anterior interbody reconstruction at L4-5 by using one of the following interbody fusion devices: four different threaded fusion cages (BAK device, BAK Proximity, Ray TFC, and Danek TIBFD), five different nonthreaded fusion devices (oval and circular Harms cages, Brantigan PLIF and ALIF cages, and InFix device); two different types of allograft (femoral ring and bone dowel) were used. Construct stiffness was evaluated in axial compression, torsion, flexion, and lateral bending. Prior to testing, a silicon elastomer was injected into the cages and intracage pressures were measured using pressure needle transducers. CONCLUSIONS: No statistical differences were observed in construct stiffness among the threaded cages and nonthreaded devices in most of the testing modalities. Threaded fusion cages demonstrated significantly lower intracage pressures compared with nonthreaded cages and structural allografts. Compared with nonthreaded cages and structural allografts, threaded fusion cages afforded equivalent reconstruction stiffness but provided more stress-shielded environment within the devices.
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Vértebras Lumbares/cirugía , Dispositivos de Fijación Ortopédica , Fusión Vertebral/instrumentación , Animales , Fenómenos Biomecánicos , Bovinos , Diseño de Equipo , Ensayo de Materiales , Presión , Estrés MecánicoRESUMEN
STUDY DESIGN: Three types of anterior thoracolumbar multisegmental fixation were biomechanically compared in construct stiffness and rod-screw strain. OBJECTIVES: To investigate the effects of rod diameter and rod number on construct stiffness and rod-screw strain in anterior thoracolumbar multisegmental instrumentation. SUMMARY OF BACKGROUND DATA: No studies have been undertaken to investigate the biomechanical effects of rod diameter and rod number in thoracolumbar anterior instrumentation. METHODS: Ten fresh-frozen calf spines (T13-L5) were used. After intact analysis, a total discectomy and transection of the ALL and PLL were performed at L1-L2, L2-L3, and L3-L4 with intervertebral reconstruction using carbon fiber cages. Three types of anterior fixation were then performed at L1-L4: 1) 4.75-mm diameter single-rod, 2) 4.75-mm dual-rod, and 3) 6.35-mm single-rod systems. Single screws at each vertebra were used for single-rod and two screws for dual-rod fixation. These systems share the same basic design except rod diameter. Nondestructive biomechanical testing was performed and included compression, torsion, flexion-extension, and lateral bending. Construct stiffness and rod-screw strain of the three reconstructions were compared. RESULTS: The 6.35-mm single-rod fixation significantly improved construct stiffness compared with the 4.75-mm single rod fixation only under torsion (P < 0.05). The 4. 75-mm dual rod construct resulted in significantly higher stiffness than did both single-rod fixations (P < 0.05), except under compression. No statistical differences were observed in rod-screw strain between the two types of single rods, whereas dual-rod reconstruction exhibited less rod-screw strain (P < 0.05). CONCLUSIONS: For single-rod fixation, increased rod diameter neither markedly improved construct stiffness nor affected rod-screw strain, indicating the limitations of a single-rod system. In thoracolumbar anterior multisegmental instrumentation, the dual-rod fixation provides higher construct stiffness and less rod-screw strain compared with single-rod fixation.
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Tornillos Óseos , Fijadores Internos , Fusión Vertebral/métodos , Animales , Fenómenos Biomecánicos , Bovinos , Fuerza Compresiva , Vértebras Lumbares/cirugía , Fusión Vertebral/instrumentación , Vértebras Torácicas/cirugíaRESUMEN
STUDY DESIGN: Motion characteristics of the lumbar spine in the sagittal plane were investigated in vivo using cineradiography. OBJECTIVES: To evaluate the differences in motion characteristics of the normal lumbar spine between forward and backward flexion. SUMMARY OF BACKGROUND DATA: Despite previous lumbar kinematic studies, differences in motion characteristics of the lumbar spine between forward and backward flexion remain unclear. METHODS: Cineradiographic motion analysis was performed in 10 asymptomatic healthy male volunteers for two different lumbar motions. The motions consisted of active forward flexion (from maximum extension to maximum flexion) and active backward flexion (from maximum flexion to maximum extension). Displacements of the anterior and posterior vertebral corners from L3/L4 to L5/S1 were measured continuously in reference to the local coordinate system. Parameters investigated were onset of segmental motion, velocity of segmental motion, and continuous motion profiles of the vertebral corners during the two different motions. RESULTS: During forward flexion, initial lumbar motion started stepwise from the upper level (L3/L4) to the lower levels with phase lags. Angular velocity at the onset of motion increased as the level descended. On the contrary, during backward flexion, initial motion started from the lower level (L5/S1) to the upper levels. There was no relation between velocity and spinal levels during backward flexion. Motion profiles of both anterior and posterior vertebral corners at L3/L4 and L4/L5 segments during forward flexion were similar to those during backward flexion. However, the motion profiles at L5/S1 segment during forward flexion were different from those during backward flexion. CONCLUSIONS: During forward flexion of the lumbar spine, initial motion started from upper segments to the lower segments with phase lags. During backward flexion, initial motion started from the lower segments to the upper segments. Motion profiles of the vertebral corners during forward flexion were similar to those during backward flexion at L3/L4 and L4/L5. The motion profiles at L5/S1 were different between both flexions.
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Cinerradiografía/métodos , Vértebras Lumbares/fisiología , Movimiento/fisiología , Adulto , Fenómenos Biomecánicos , Humanos , Masculino , Variaciones Dependientes del Observador , Rango del Movimiento Articular , Reproducibilidad de los ResultadosRESUMEN
STUDY DESIGN: This retrospective study was designed to analyze the results of the treatment with S1 pedicle screws and the Galveston technique of seven patients with sacroiliac dislocation. OBJECTIVES: To evaluate the effectiveness of the combined use of S1 pedicle screws and the Galveston technique for the treatment of sacroiliac dislocation. SUMMARY OF BACKGROUND DATA: Although several procedures for internal fixation of sacroiliac dislocation have been reported, there have been no reports discussing surgical treatment of sacroiliac dislocation by the combined use of S1 pedicle screws and the Galveston technique. METHODS: Seven patients with sacroiliac dislocation were treated with pedicle screws of S1 and iliac rod according to the Galveston technique. In the seven patients, the dislocation was associated with vertical displacement of the sacroiliac joint and rotational deformity of the pelvic ring. They were classified into Type-C pelvic disruption according to the Tile's classification. Three patients with disruption of the symphysis pubis underwent additional fixation of the symphysis using a dynamic compression plate. The remaining four patients were treated by the posterior procedure alone. RESULTS: The vertical displacement was completely reduced in five patients, and the rotational deformity was completely corrected in four patients. The reduction was maintained at the time of the final follow-up evaluation. There were no perioperative complications with the exception of late infection in one patient. CONCLUSIONS: The combined use of S1 pedicle screws and the Galveston technique provided immediate stability and sufficient reduction for sacroiliac dislocation in seven patients in this study. This hybrid internal fixation procedure is useful for reduction and fixation of sacroiliac dislocation associated with the vertical and rotational instability of the pelvic ring.
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Tornillos Óseos , Fijadores Internos , Luxaciones Articulares/cirugía , Articulación Sacroiliaca/cirugía , Fusión Vertebral/instrumentación , Adulto , Femenino , Humanos , Luxaciones Articulares/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Aparatos Ortopédicos , Radiografía , Estudios Retrospectivos , Articulación Sacroiliaca/diagnóstico por imagen , Resultado del TratamientoRESUMEN
STUDY DESIGN: Retrospective evaluation of complications in 180 consecutive patients with cervical disorders who had been treated by using pedicle screw fixation systems. OBJECTIVES: To determine the risks associated with pedicle screw fixation in the cervical spine and to emphasize the importance of preoperative planning and surgical techniques in reducing the risks of this procedure. SUMMARY OF BACKGROUND DATA: Generally, pedicle screw fixation in the cervical spine has been considered too risky for the neurovascular structures. There have been several reports describing the complications of lateral mass screw-plate fixation. However, no studies have examined in detail the complications associated with cervical pedicle screw fixation. METHODS: One hundred eighty patients who underwent cervical reconstructive surgery using cervical pedicle screw fixation were reviewed to clarify the complications associated with the pedicle screw fixation procedure. Cervical disorders were spinal injuries in 70 patients and nontraumatic lesions in 110 patients. Seven hundred twelve screws were inserted into the cervical pedicles, and the locations of 669 screws were radiologically evaluated. RESULTS: Injury of the vertebral artery occurred in one patient. The bleeding was stopped by bone wax, and no neurologic complication developed after surgery. On computed tomographic (CT) scan, 45 screws (6.7%) were found to penetrate the pedicle, and 2 of 45 screws caused radiculopathy. Besides these three neurovascular complications directly attributed to screw insertion, radiculopathy caused by iatrogenic foraminal stenosis from excessive reduction of the translational deformity was observed in one patient. CONCLUSIONS: The incidence of the clinically significant complications caused by pedicle screw insertion was low. Complications associated with cervical pedicle screw fixation can be minimized by sufficient preoperative imaging studies of the pedicles and strict control of screw insertion. Pedicle screw fixation is a useful procedure for reconstruction of the cervical spine in various kinds of disorders and can be performed safely.
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Tornillos Óseos , Vértebras Cervicales/cirugía , Procedimientos de Cirugía Plástica/métodos , Complicaciones Posoperatorias , Enfermedades de la Columna Vertebral/cirugía , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Vértebras Cervicales/diagnóstico por imagen , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , Enfermedades de la Columna Vertebral/diagnóstico por imagen , Fusión Vertebral , Tomografía Computarizada por Rayos X , Resultado del TratamientoRESUMEN
OBJECT: In this study the authors retrospectively review 16 patients with traumatic disc herniation secondary to middle and lower cervical spine injuries who underwent a single posterior reduction and fusion procedure in which a cervical pedicle screw system was used. The study was undertaken to evaluate whether the procedure effectively reduced the disc herniation and whether it can be safely conducted without performing anterior decompressive surgery. METHODS: A total of 73 patients with middle and lower cervical spine injuries were identified. In 50 patients, pre- and postoperative magnetic resonance (MR) images were obtained, and disc herniation was defined as the presence of an extruded disc that deformed the thecal sac or nerve roots. Traumatic disc herniation was revealed in 16 patients (32%) who underwent a single posterior reduction/fusion procedure in which a cervical pedicle screw system was used. The average follow-up period was 4.25 years (2-6.25 years). In all patients the average kyphotic deformity was 18 degrees, which was corrected to 0.7 degrees lordosis postoperatively. Anterior translation was reduced from 8 to 0.7 mm. The preoperative disc height ratio of 63% (normal 100%) was improved to 104%. Preoperative MR images revealed traumatic disc herniation in all 16 patients; postsurgery, reduction or reversal of disc herniation was observed in all patients. Thecal sac and/or spinal cord compression had disappeared after indirect decompression was achieved using a posterior procedure. No additional decompressive procedures were required to remove residual herniated disc material. Preoperatively, four patients presented with cervical radiculopathy, 10 with myelopathy (eight incomplete and two complete), and two without neurological symptoms. At final follow up, complete recovery was observed in all four patients with radiculopathy and improvement of at least one Frankel grade was shown in six patients (60%) with myelopathy. There were no cases of neurological deterioration immediately after surgery or during the course of the follow-up period. In all patients solid bone union was demonstrated, and there were no implant-related complications. CONCLUSIONS: Traumatic disc herniation may occur frequently in association with injury of the cervical spine. The incidence of traumatic disc herniation in our series was 32%. The cervical pedicle screw system allowed three-dimensional reduction of the injured cervical segment and reduction or reversal of a disc herniation. After surgery, compression of the thecal sac and/or spinal cord had disappeared. The cervical pedicle screw system provides effective and safe fixation of the cervical spine injury-related traumatic disc herniation, and the surgery can be performed safely in a single posterior-approach procedure without need of additional anterior decompressive interventions.
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Tornillos Óseos , Vértebras Cervicales/lesiones , Desplazamiento del Disco Intervertebral/cirugía , Fusión Vertebral/métodos , Adolescente , Adulto , Anciano , Vértebras Cervicales/diagnóstico por imagen , Vértebras Cervicales/patología , Femenino , Humanos , Incidencia , Desplazamiento del Disco Intervertebral/complicaciones , Desplazamiento del Disco Intervertebral/diagnóstico , Desplazamiento del Disco Intervertebral/epidemiología , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Mielografía , Estudios Retrospectivos , Factores de Riesgo , Traumatismos de la Médula Espinal/complicaciones , Fusión Vertebral/instrumentación , Tomografía Computarizada por Rayos XRESUMEN
STUDY DESIGN: The stabilizing effects of five different occipitocervical fixations were compared. OBJECTIVES: To evaluate the construct stability provided by five different occipito-atlanto-axial fixation techniques. SUMMARY OF BACKGROUND DATA: Few studies have addressed occipitocervical reconstruction stability and no studies to data have investigated anterior-posterior translational stiffness. METHODS: A total of 21 human cadaveric spines were used. After testing intact spines (CO-C2), a type II dens fracture was created and five different reconstructions were performed: 1) occipital and sublaminar wiring/rectangular rod, 2) occipital screws and C2 lamina claw hooks/rod, 3) occipital screws, foramen magnum screws, and C1-C2 transarticular screws/rod, 4) occipital screws and C1-C2 transarticular screws/Y-plate, and 5) occipital screws and C2 pedicle screws/rod. Biomechanical testing parameters included axial rotation, flexion/extension, lateral bending, and anterior-posterior translation. RESULTS: Pedicle screw fixation demonstrated the highest stiffness among the five reconstructions (P < 0.05). The two types of transarticular screw methods provided greater stability than hook or wiring reconstructions (P < 0.05). The C2 claw hook technique resulted in greater stability than sublaminar wiring fixation in anterior-posterior translation (P < 0.05). However, the wiring procedure did not significantly increase the stiffness levels beyond the intact condition under anterior-posterior translation and lateral bending (P > 0.05). DISCUSSION: C2 transpedicular and C1-C2 transarticular screws significantly increased the stabilizing effect compared to sublaminar wiring and lamina hooks. The improved stability afforded by C2 pedicular and C1-C2 transarticular screws offer many potential advantages including a high rate of bony union, early ambulation, and easy nursing care. CONCLUSION: Occipitocervical reconstruction techniques using C1-C2 transarticular screws or C2 pedicle screws offer biomechanical advantages compared to sublaminar wiring or lamina hooks. Pedicle screw fixation exhibited the highest construct stiffness among the five reconstructions.
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Articulación Atlantoaxoidea/cirugía , Articulación Atlantooccipital/cirugía , Fusión Vertebral/métodos , Anciano , Articulación Atlantoaxoidea/fisiología , Articulación Atlantooccipital/fisiología , Fenómenos Biomecánicos , Clavos Ortopédicos , Tornillos Óseos , Hilos Ortopédicos , Cadáver , Femenino , Humanos , Masculino , Fusión Vertebral/instrumentaciónRESUMEN
STUDY DESIGN: This retrospective study was conducted to analyze the clinical results in 30 patients with cervical kyphosis that had been treated using cervical pedicle screw fixation systems. OBJECTIVES: To evaluate the effectiveness of a pedicle screw fixation procedure in correction of cervical kyphosis. SUMMARY OF BACKGROUND DATA: Correction of cervical kyphosis is a challenging problem in the field of spinal surgery. There have been several reports regarding surgical correction of cervical kyphosis; however, there have been no detailed reports on correction of cervical kyphosis using a pedicle screw fixation procedure. METHODS: Thirty patients with cervical kyphosis underwent correction and fusion using cervical pedicle screw fixation. Seventeen of 30 patients with flexible kyphosis (Group I) were managed by a posterior procedure alone. The remaining 13 patients with rigid or fixed kyphosis (Group II) had a combined anterior and posterior procedure. RESULTS: The average preoperative cervical kyphosis of 29.4 degrees improved to 2.3 degrees after surgery and was 2.8 degrees at the final follow-up. In Group I patients, preoperative kyphosis of 28.4 degrees improved to 5.1 degrees at the final follow-up. In contrast, preoperative kyphosis of 30.8 degrees in Group II patients improved to 0.5 degree at the final follow-up. Solid fusion was achieved in all patients. There were two patients with transient nerve root complications related to pedicle screw instrumentation. CONCLUSION: Cervical kyphosis in 30 patients was effectively corrected using a pedicle screw fixation procedure with no serious complications. Flexible kyphosis with segmental motion can be satisfactorily corrected by a single posterior procedure using pedicle screw fixation. However, circumferential osteotomies combined with a posterior shortening procedure involving a pedicle screw system are required to achieve the best correction of fixed kyphosis by bony union. Cervical pedicle screw fixation is the most advantageous instrumentation in the correction of cervical kyphosis.
Asunto(s)
Tornillos Óseos , Vértebras Cervicales/cirugía , Cifosis/cirugía , Fusión Vertebral/instrumentación , Estudios de Casos y Controles , Vértebras Cervicales/diagnóstico por imagen , Femenino , Estudios de Seguimiento , Humanos , Cifosis/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Radiografía , Fusión Vertebral/métodos , Factores de TiempoRESUMEN
STUDY DESIGN: After total spondylectomy, five types of spinal reconstruction techniques were compared biomechanically. OBJECTIVES: To evaluate the stability provided by five reconstruction methods after total spondylectomy. SUMMARY OF BACKGROUND DATA: Total spondylectomy presents a worst-case scenario for spinal reconstruction. However, few investigators have biomechanically investigated spinal reconstruction stability after total spondylectomy. METHODS: Eight human cadaveric spines (T11-L5) were used. After intact analysis, a total spondylectomy was performed at L2 and reconstructed using Harms titanium mesh (Depuy-Motech, Warsaw, IN) as an anterior strut. Anterior, posterior, or circumferential instrumentation techniques were then performed using the Kaneda SR and ISOLA pedicle screw systems (AcroMed Corp., Cleveland, OH) as follows: 1) anterior instrumentation at L1-L3 with multisegmental posterior instrumentation at T12-L4 (AMP), 2) anterior instrumentation at L1-L3 with short posterior instrumentation at L1-L3 (ASP), 3) anterior instrumentation at L1-L3 (A), 4) multilevel posterior instrumentation at T12-L4 (MP), and 5) short posterior instrumentation at L1-L3 (SP). Nondestructive biomechanical testing was performed under axial compression, flexion-extension, and lateral bending loading modes. RESULTS: Only circumferential instrumentation techniques (AMP, ASP) exhibited higher stiffness than the intact spine in all loading modes (P < 0.05). Short circumferential fixation provided more stability than did multilevel posterior instrumentation (P < 0.05). Multilevel posterior fixation provided more stiffness than did short posterior and anterior instrumentation alone (P < 0.05). CONCLUSIONS: Only circumferential fixation techniques provide more stability than the intact spine in all testing modes. Short circumferential instrumentation provides more stability than multilevel posterior instrumentation alone and requires fewer levels of spinal fusion.
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Vértebras Lumbares/cirugía , Dispositivos de Fijación Ortopédica , Columna Vertebral/fisiopatología , Vértebras Torácicas/cirugía , Anciano , Fenómenos Biomecánicos , Cadáver , Humanos , Persona de Mediana Edad , Periodo Posoperatorio , Presión , Radiografía , Columna Vertebral/diagnóstico por imagen , Procedimientos Quirúrgicos Operativos , Soporte de PesoRESUMEN
OBJECT: This retrospective study was conducted to analyze the results of one-stage posterior decompression and reconstruction of the cervical spine by using pedicle screw fixation systems in 46 patients. METHODS: Causes of cervical myelopathy in these 46 patients included spondylosis or ossification of the posterior longitudinal ligament, rheumatoid arthritis, metastatic or primary vertebral tumors, cervical spinal injuries, and spinal cord tumor. Thirty-three patients underwent this one-stage procedure as primary surgery. In the remaining 13 patients who had previously undergone laminectomies, the one-stage procedure was performed as salvage surgery. Cervical pedicle screws were inserted into the pedicles after probing and tapping. Graft bone was placed on the bilateral lateral masses, and pedicle screws were interconnected longitudinally by either plates or rods. Postoperatively, 26 patients showed improved neurological status (at least one grade improvement on Frankel's functional classification). There were no cases of neurological deterioration postoperatively. Solid bony fusion was obtained in all patients, except in seven patients with metastatic tumor who did not receive bone grafts. Correction of kyphosis was satisfactory. Postoperative radiological evaluation revealed that 10 (5.3%) of 190 screws inserted into the cervical vertebrae had perforated the cortex of the pedicles; however, no neurovascular complications were caused by the perforations. CONCLUSIONS: The pedicle screw fixation procedure, which does not require the lamina to be used as a stabilizing anchor, has proven to be valuable when performing one-stage posterior decompressive and reconstructive surgery in the cervical spine. The risk to neurovascular structures in this procedure, however, cannot be completely eliminated. Thorough knowledge of local anatomy and application of established surgical techniques are essential for this procedure.
Asunto(s)
Tornillos Óseos , Vértebras Cervicales/cirugía , Descompresión Quirúrgica/métodos , Enfermedades de la Columna Vertebral/cirugía , Adulto , Anciano , Tornillos Óseos/efectos adversos , Descompresión Quirúrgica/efectos adversos , Diseño de Equipo , Femenino , Humanos , Laminectomía , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
STUDY DESIGN: Biomechanical evaluation was performed to investigate the stability of the thoracic spine. Unilateral resection of the intervertebral disc, the rib head joint, and the costotransverse joint were sequentially performed, and nondestructive cyclic loading tests were conducted at each injury stage to examine the roles of the intervertebral disc and the costovertebral joint of the thoracic spine. The effects of each resection were three-dimensionally analyzed as the main motion and the associated coupled motions. OBJECTIVE: To examine the role of the intervertebral disc and the costovertebral joint in stability of the thoracic spine. SUMMARY OF BACKGROUND DATA: The effects of unilateral resection of the intervertebral disc and the costovertebral joints in the thoracic spine with the rib cage have not been documented three-dimensionally in a biomechanical study. MATERIALS AND METHODS: Ten canine rib cage-thoracic spine complexes, consisting of the sixth to eighth ribs, the sternum and T5-T8 vertebrae, were used. Six pure moments along three axes, flexion-extension, lateral bending, and axial rotation, were applied to the specimen, and the angular deformation between T6-T7 was recorded by a stereophotogrammetric method. After the intact specimens were tested, staged resections were conducted in the following manner: partial resection of the T6-T7 intervertebral disc, performed as a resection of the anterior longitudinal ligament, the nucleus pulposus, and the annulus fibrosus on the approach side, leaving the posterior longitudinal ligament intact; resection of the right seventh rib head with the joint capsule; and resection of the right seventh costotransverse joint. At each stage, the main motion and associated coupled motions were determined three dimensionally. RESULTS: The ranges of motion (ROM) in flexion-extension, lateral bending, and axial rotation were significantly increased after partial discectomy (P < 0.01). Moreover, along with large increases in the ROM of the main motions in left axial rotation and right lateral bending, coupled motions, expressed by right lateral bending and left axial rotation, showed marked increases after resection of the rib head joint (P < 0.05). The neutral zones also increased in lateral bending, axial rotation, and flexion-extension after partial discectomy (P < 0.01). A further increase in the neutral zone was observed in lateral bending after resection of the right seventh rib head (P < 0.01). CONCLUSIONS: In this canine spine model, the intervertebral disc regulates the stability of the thoracic spine in flexion-extension, lateral bending, and axial rotation. Moreover, the articulation of the rib head with the vertebral bodies provides stability to the thoracic spine in lateral bending and axial rotation. Unilateral resection of the rib head joint after partial discectomy on the same side produces significant coupled motions in lateral bending and axial rotation, resulting in a significant decrease in thoracic spinal stability, and integrity.
Asunto(s)
Disco Intervertebral/fisiología , Costillas/fisiología , Vértebras Torácicas/fisiología , Animales , Fenómenos Biomecánicos , Discectomía , Perros , Rango del Movimiento Articular , Esternón/fisiologíaRESUMEN
STUDY DESIGN: This retrospective study was conducted to analyze the clinical results in 26 patients with lesions at the craniocervical junction that had been treated by occipitocervical reconstruction using pedicle screws in the cervical spine and occipitocervical rod systems. OBJECTIVES: To evaluate the effectiveness of pedicle screw fixation in occipitocervical reconstructive surgery and to introduce surgical techniques. SUMMARY OF BACKGROUND DATA: Many methods of occipitocervical reconstruction have been reported, but there have been no reports of occipitocervical reconstruction using pedicle screws and occipitocervical rod systems for reduction and fixation. METHODS: Twenty-six patients with lesions at the craniocervical junction underwent reconstructive surgery using pedicle screws in the cervical spine and occipitocervical rod systems. The occipitocervical lesions were atlantoaxial subluxation associated with basilar invagination, which was caused by rheumatoid arthritis in 19 patients and other disorders in 7. The lowest cervical vertebra of fusion in 16 patients was C2, and the remaining 10 patients underwent fusion downward from C3 to C7. Flexion deformity of the occipitoatlantoaxial complex was corrected by application of extensional force, and upward migration of the odontoid process was reduced by application of combined force of extension and distraction between the occiput and the cervical pedicle screws. RESULTS: Solid fusion was achieved in all patients except two with metastatic vertebral tumors who did not receive bone graft for fusion. Correction of malalignment at the craniocervical junction was adequate, and postoperative magnetic resonance imaging showed improvement of anterior compression of the medulla oblongata. There were no neurovascular complications of cervical pedicle screws. CONCLUSIONS: Occipitocervical reconstruction by the combination of cervical pedicle screws and occipitocervical rod systems provided the high fusion rate and sufficient correction of malalignment in the occipitoatlantoaxial region. Results of this study showed the effectiveness of cervical pedicle screw as a fixation anchor for occipitocervical reconstruction.