摘要:

Multicenter human clinical studies of patients undergoing anterior lumbar fusion have been conducted using recombinant bone morphogenetic protein or rhBMP-2 on an absorbable collagen sponge, marketed as INFUSE Bone Graft, or autograft implanted in the LT-CAGE Lumbar Tapered Fusion device. An integrated analysis of multiple clinical studies was performed using an analysis of covariance to adjust for preoperative variables in a total of 679 patients. Of these patients, 277 had their cages implanted with rhBMP-2 on an absorbable collagen sponge and 402 received autograft transferred from the iliac crest. The patients treated with rhBMP-2 had statistically superior outcomes with regard to length of surgery, blood loss, hospital stay, reoperation rate, median time to return to work, and fusion rates at 6, 12, and 24 months. Oswestry Disability Index scores and the Physical Component Scores and Pain Index of the SF-36 scale at 3, 6, 12, and 24 months showed statistically superior outcomes in the rhBMP-2 group.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

This is a retrospective review of 32 patients with multilevel cervical myelopathy treated by laminectomy and lateral mass plate fusion. The prognosis of surgically treated myelopathy is evaluated as well as prognostic factors for recovery of myelopathy. Diagnoses included cervical spondylosis or ossification of the posterior longitudinal ligament. Final follow-up was at 15.2 months (mean) postoperatively. Myelopathy was graded preoperatively and postoperatively by the system of Nurick. All patients had preoperative radiographs and magnetic resonance imaging (MRI). The presence of abnormal T2-weighted MRI signal (myelomalacia) was noted. Postoperative studies included flexion–extension radiographs to assess fusion and MRI to evaluate decompression of neural elements and resolution of myelomalacia. Severity of preoperative Nurick myelopathy, presence of myelomalacia, and age were evaluated as potential prognostic indicators for surgically treated myelopathy. Mean Nurick score improved from 2.6 (range 1–4) to 1.8 (range 0–3) postoperatively (p < 0.0001). Twenty-two patients (71%) had improvement in Nurick grade of at least one point, and nine showed no improvement. No patients had deterioration of Nurick grade. Preoperative myelomalacia was noted in 15 (47%) patients, and all 15 had residual myelomalacia postoperatively. Severe myelopathy, age, and myelomalacia had no prognostic value for improvement of myelopathy. Complications included pseudarthrosis (3%), wound infection (9%), and transient C5 palsy (6%). This study demonstrates excellent outcomes from laminectomy and fusion in multilevel cervical myelopathy. A high rate of improvement of myelopathy was observed, neurologic deterioration did not occur, and complication rates were low. Severe myelopathy and myelomalacia on preoperative MRI had no prognostic value.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Magnetic resonance imaging changes to the symptomatic intervertebral disc following intradiscal electrothermal therapy were determined in this prospective study. Magnetic resonance images before the intradiscal electrothermal therapy procedure were compared with those taken at 6 months postprocedure in 10 patients. The presence and absence of high-intensity zone, the disc height and hydration, and Modic changes were determined from the images. In six of the 10 patients, a high-intensity zone was present on the magnetic resonance images of the disc before the intradiscal electrothermal therapy procedure. In all six patients, a high-intensity zone was still present after the procedure. In all 10 patients, there were no changes to other disc parameters assessed. Our findings question the clinical relevance of the high-intensity zone. They also suggest that the main mechanism of action of intradiscal electrothermal therapy may be other than that of sealing the anular tear.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The purpose of this study was to achieve spinal fusion in the absence of bone graft material using a new, injectable, and semi-liquid synthetic polymer (polylactic acid polyethylene glycol [PLA-PEG] block copolymer) containing recombinant human bone morphogenetic protein-2 (rhBMP-2). Twenty-seven skeletally mature beagles underwent anterior thoracic spinal fusion at T9–T10. Group I (n = 9) was injected with 1 mL of PLA-PEG block copolymer carrier alone into space under the vertebral pleura and the anterior longitudinal ligament. Group II (n = 9) was injected with 1 mL of PLA-PEG carrier containing 500 &mgr;g of rhBMP-2. Group III (n = 9) was injected with 1 mL of PLA-PEG carrier containing 1000 &mgr;g of rhBMP-2. In the Group I animals, no evidence of new bone formation was noted at the implanted sites both radiographically and histologically. In contrast, all of the nine animals in Group III showed new bone formation in 12 weeks, and four of the nine animals in Group II showed bony mass at the injected sites. However, vertebral bony fusion was incomplete despite the significant amount of new bone formation in both groups that showed new bone formation. In addition to resulting in improvements in the surgical procedure, injection of rhBMP-2 and a synthetic polymer is useful for bone formation for spinal fusion.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The current study is a biomechanical study using a cadaveric model of L5–S1 spondylolisthesis. The purpose of the current study was to compare, in a cadaveric model of simulated L5–S1 spondylolisthesis, the biomechanical stiffness of transdiscal fixation with traditional pedicle screw fixation, and transdiscal fixation with combined interbody/pedicle screw fixation. The surgical management of L5–S1 spondylolisthesis is a challenge because of the difficulties in achieving a reliable arthrodesis in the face of high mechanical forces. A method of lumbosacral fixation that has been used successfully in moderate grades of spondylolisthesis at our institution involves the use of transdiscal S1 pedicle screws. With this technique, S1 pedicle screws are placed through the S1 pedicle, through the superior endplate of S1, through the inferior endplate of L5, to terminate in the L5 body. Eighteen fresh human cadaveric (age 59–88 years) L5–S1 motion segments were obtained. The end of each intact motion segment was potted up to its midbody in a 10-cm-diameter polyvinylchloride end-cap using dental cement. The intact specimen was then biomechanically tested as follows: 1) axial compression (500 N), 2) flexion (10 Nm), 3) extension (10 Nm), 4) right lateral bending (10 Nm), and 5) left lateral bending (10 Nm). Stiffness values were calculated from the load–deflection curves obtained. Spondylolisthesis was then simulated by displacing L5 on S1 (% slip average = 41.3%) after performing a radical L5–S1 discectomy, L5 laminectomy, and bilateral L5–S1 facetectomies. The 18 motion segments were divided into two groups. Group I (n = 10) was biomechanically tested (as above) after pedicle screw fixation and again after replacing the S1 pedicle screws with transdiscal screws. Group II (n = 8) was biomechanically tested (as above) after combined interbody/pedicle screw fixation and again after fixation with transdiscal screws. Load–deflection curves were obtained each time, and stiffness values were calculated from the curves. Transdiscal fixation was 1.6–1.8 times stiffer than pedicle screw fixation (p < 0.05) in all loading modes tested. There were no differences in stiffness between transdiscal fixation and combined interbody/pedicle screw fixation. In a cadaveric model of simulated L5–S1 spondylolisthesis, transdiscal L5–S1 fixation produced a 1.6–1.8 times stiffer construct than traditional pedicle screw fixation. Further, the stiffness of the transdiscal fixation was equal to that of a combined interbody/pedicle screw fixation.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

A retrospective assessment of 809 patients operated on in 1990–1998 was performed. A patient-based outcome questionnaire also was incorporated into the study. The outcome was graded according to the Functional Economic Rating scale. A total of 64% of the patients were relieved of their complaints 3.2–10.2 years (median 6.3 years) after lumbar disc surgery. An excellent outcome, defined as Prolo scale of 9 or 10, was achieved in 55.8%, a good outcome (Prolo scale 7 or 8) in 20.7%, a fair outcome (Prolo scale 5 or 6) in 11.4%, and a poor outcome (Prolo scale of ≤4) in 12.1% of the patients. Patients with strenuous occupations had a significantly (P= 0.004) less favorable outcome than patients with less strenuous or sedentary occupations. Criteria for evaluating the results of treating lumbar spinal disorders vary widely. A more universal acceptance of common criteria for judging the outcome of spinal operations should facilitate comparisons among various methods of treatment.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

This study is a retrospective review of patients with pediatric laminoplasty. The objective was to determine the incidence of postlaminoplasty deformity. Long-term follow-up of patients with pediatric laminoplasty is lacking. Previous studies have shown spine deformity to be as high as 100% following laminectomy procedures. From 1986 until present, 31 superiorly based laminoplasties were performed on pediatric patients, ranging from two to 12 levels. Twenty-one of the 31 were available for complete review. A retrospective review of the radiographic deformity of these patients was conducted. Preoperative and postoperative scoliotic and kyphotic deformities were measured, and the correlating diagnoses were recorded. The average follow-up period was 6.8 years, and average age at follow-up was 11.9 years. Sixteen of 21 showed no increase in spinal deformity. Five of 21 showed nonunion at one or more levels. Five patients showed an increased deformity, of which two required surgical intervention to correct deformity. Although the technique of laminoplasty has very low morbidity (essentially no different from laminectomy), this review has not shown that this procedure eliminates postsurgical deformity. However, we recommend the use of laminoplasty in the pediatric patient because it may reduce the incidence of deformity, allow future segmental instrumentation if necessary, and has a low morbidity.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

We evaluated the function of the descending spinal cord motor tracts in patients, with and without spinal cord lesion, using motor evoked potentials. We studied 50 normal volunteers and 15 patients with thoracic lesions. The onset latency of the negative waves of motor evoked potentials for the thoracic spines was obtained, and the descending spinal cord conduction time was measured for the thoracic segments. In normal subjects, motor evoked potentials of paravertebral muscles recorded from T1–T2 to T5–T6 initially appeared as negative waveform with transcutaneous electrical stimulation over occipitocervical junction, although those from T6–T7 to T8–T9 were initially positive and those from more caudal sites were flatter. The motor evoked potential waveforms of tibialis anterior muscles evoked by electrical stimulation over the occipitocervical junction were markedly similar to those over the L1–L2. In patients with upper thoracic lesions, descending spinal cord conduction time from T2–T3 to T5–T6 was prolonged (p < 0.01). The descending spinal cord conduction time from T5–T6 to T11–T12 was also prolonged (p < 0.01) in patients with lower thoracic lesion. The descending spinal cord conduction time from T2–T3 to T11–T12 in patients with smaller motor function scores (<2) was significantly prolonged (p < 0.01) compared with normal subjects and patients with larger function scores. The methods of recording motor evoked potentials from paravertebral muscles with transcutaneous electrical stimulation over occipitocervical junction were useful for evaluating the level and motor function of thoracic cord lesions.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Nine cadaver lumbar spines were analyzed by applying nonconstraining nondestructive bending moments while measuring global range of motion, mechanical reaction at the sacrum, applied moment at the top of the specimen, segmental range of motion at L1–L5, and IDP at L1–L4. Each specimen was examined in an intact and instrumented state (with L3–L4 posterior instrumentation) using range of motion-based biomechanical testing, while achieving a similar global ROM in the sagittal, frontal, and transverse planes. An increase in applied moment was required during instrumented testing when compared with intact, and a significant increase in segmental range of motion during instrumented testing was found at all uninstrumented levels. Significant decreases in segmental range of motion were measured at the instrumented level when compared with intact testing. The most significant decreases and increases in IDP occurred at the instrumented level during sagittal and transverse plane testing.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Methods to quantify burst fracture risk and neurologic deficit for patients with spinal metastases have not been well defined. This study aims to develop objective biomechanically based guidelines to quantify metastatic burst fracture risk. An experimentally validated finite element model of a human lumbar motion segment was used to simulate burst fracture. Through parametric analysis, the behavior of metastatically involved vertebrae was quantified and a formula to relate patient-specific variables to burst fracture risk defined. The equation-based guidelines were able to describe the mechanical behavior of the metastatically involved vertebral model (R2= 0.97) reflecting the risk and mechanism of fracture. Vertebral density was found to influence the mechanism of burst fracture with respect to endplate failure. These analyses provide clinically feasible equation-based guidelines for burst fracture risk assessment in the metastatically involved spine.

ISSN:1536-0652    

出版商:OVID    

年代:2003

数据来源: OVID