To investigate the effects of postoperative fusion implantation on the mesoscopic biomechanical properties of vertebrae and bone tissue osteogenesis in idiopathic scoliosis, a macroscopic finite element model of the postoperative fusion device was developed, and a mesoscopic model of the bone unit was developed using the Saint Venant sub-model approach. To simulate human physiological conditions, the differences in biomechanical properties between macroscopic cortical bone and mesoscopic bone units under the same boundary conditions were studied, and the effects of fusion implantation on bone tissue growth at the mesoscopic scale were analyzed. The results showed that the stresses in the mesoscopic structure of the lumbar spine increased compared to the macroscopic structure, and the mesoscopic stress in this case is 2.606 to 5.958 times of the macroscopic stress; the stresses in the upper bone unit of the fusion device were greater than those in the lower part; the average stresses in the upper vertebral body end surfaces were ranked in the order of right, left, posterior and anterior; the stresses in the lower vertebral body were ranked in the order of left, posterior, right and anterior; and rotation was the condition with the greatest stress value in the bone unit. It is hypothesized that bone tissue osteogenesis is better on the upper face of the fusion than on the lower face, and that bone tissue growth rate on the upper face is in the order of right, left, posterior, and anterior; while on the lower face, it is in the order of left, posterior, right, and anterior; and that patients' constant rotational movements after surgery is conducive to bone growth. The results of the study may provide a theoretical basis for the design of surgical protocols and optimization of fusion devices for idiopathic scoliosis.
Humans ; Scoliosis/surgery* ; Spinal Fusion/methods* ; Lumbar Vertebrae/surgery* ; Osteogenesis ; Biomechanical Phenomena/physiology* ; Finite Element Analysis

BACKGROUND: Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries. However, there are several inherent limitations. In this study, a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility. METHODS: Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant. Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility. Twenty-four rabbits were performed discectomy only (control group), discectomy with autologous bone implanted (autograft group), and discectomy with porous tantalum implanted (tantalum group) at 3 levels: L3-L4, L4-L5, and L5-L6 in random order. All the 24 rabbits were randomly sacrificed at the different post-operative times (2, 4, 6, and 12 months; n = 6 at each time point). Histologic examination and micro-computed tomography scans were done to evaluate the fusion process. Comparison of fusion index scores between groups was analyzed using one-way analysis of variance. Other comparisons of numerical variables between groups were made by Student t test. RESULTS: All rabbits survived and recovered without any symptoms of nerve injury. Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ± 0.32 vs. 2.83 ± 0.38, F = 244.60, P = 0.709). Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ± 0.06 vs. 1.23 ± 0.04, t = -0.644, P = 0.545), which indicated the BMSC proliferation without toxicity. SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant. No implant degradation, wear debris, or osteolysis was observed. Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces. CONCLUSION This novel porous tantalum implant showed a good biocompatibility and osteocompatibility, which could be a valid biomaterial for interbody fusion cages.
Animals ; Cell Proliferation ; physiology ; Diskectomy ; Lumbar Vertebrae ; surgery ; Microscopy, Electron, Scanning ; Prostheses and Implants ; Rabbits ; Spinal Fusion ; Tantalum ; chemistry

In order to study the mechanical behavior of degeneration and nucleotomy of lumbar intervertebral disc, compression experiments with porcine lumbar intervertebral discs were carried out. The lumbar intervertebral discs with trypsin-treated and nucleus nucleotomy served as the experimental group and the normal discs as the control group. Considering the effects of load magnitude and loading rate, the relationship between stress and strain, instantaneous elastic modulus and creep property of intervertebral disc were obtained. The creep constitutive model was established. The results show that the strain and creep strain of the experimental group increase significantly with the increase of compression load and loading rate, whereas the instantaneous elastic modulus decreases obviously, compared with the control group. It indicates that the effect of load magnitude and loading rate on load-bearing capacity of intervertebral disc after nucleotomy is larger obviously than that of normal disc. The creep behavior of the experimental group can be still predicted by the Kelvin three-parameter solid model. The results will provide theoretical foundation for clinical treatment and postoperative rehabilitation of intervertebral disc disease.
Animals ; Biomechanical Phenomena ; Intervertebral Disc ; physiology ; surgery ; Lumbar Vertebrae ; Stress, Mechanical ; Swine ; Weight-Bearing

INTRODUCTIONThis retrospective review aimed to examine the relationship between preoperative pulmonary function and the Cobb angle, location of apical vertebrae and age in adolescent idiopathic scoliosis (AIS). To our knowledge, there have been no detailed analyses of preoperative pulmonary function in relation to these three factors in AIS.

METHODSA total of 38 patients with thoracic or thoracolumbar scoliosis were included. Curvature of spinal deformity was measured using the Cobb method. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were used to evaluate preoperative pulmonary function. Statistical methods were used to analyse the relationship between preoperative pulmonary function and the factors that may contribute to poor pulmonary function.

RESULTSThe mean age of the patients was 16.68 ± 6.04 years. An inverse relationship was found between the degree of the Cobb angle and FVC as well as FEV1; however, the relationships were not statistically significant (p = 0.057 and p = 0.072, respectively). There was also a trend towards a significant negative correlation between the thoracic curve and FVC (p = 0.014). Patients with larger thoracic curves had lower pulmonary function. A one-year increase in age significantly decreased FVC by 1.092 units (p = 0.044). No significant relationship between age and preoperative FEV1 was found. The median FVC was significantly higher in patients with affected apical vertebrae located at levels L1-L3 than at T6-T8 or T9-T12 (p = 0.006).

CONCLUSIONLung function impairment was seen in more severe spinal deformities, proximally-located curvature and older patients.

Adolescent ; Adult ; Female ; Follow-Up Studies ; Forced Expiratory Volume ; physiology ; Humans ; Kyphosis ; diagnosis ; physiopathology ; surgery ; Lumbar Vertebrae ; Lung ; physiopathology ; Male ; Preoperative Period ; Respiratory Function Tests ; Retrospective Studies ; Scoliosis ; diagnosis ; physiopathology ; surgery ; Severity of Illness Index ; Spinal Fusion ; methods ; Thoracic Vertebrae ; Young Adult

BACKGROUND: To evaluate the effect of spondylolisthesis on lumbar lordosis on the OSI (Jackson; Orthopaedic Systems Inc.) frame. Restoration of lumbar lordosis is important for maintaining sagittal balance. Physiologic lumbar lordosis has to be gained by intraoperative prone positioning with a hip extension and posterior instrumentation technique. There are some debates about changing lumbar lordosis on the OSI frame after an intraoperative prone position. We evaluated the effect of spondylolisthesis on lumbar lordosis after an intraoperative prone position. METHODS: Sixty-seven patients, who underwent spinal fusion at the Department of Orthopaedic Surgery of Gwangmyeong Sungae Hospital between May 2007 and February 2012, were included in this study. The study compared lumbar lordosis on preoperative upright, intraoperative prone and postoperative upright lateral X-rays between the simple stenosis (SS) group and spondylolisthesis group. The average age of patients was 67.86 years old. The average preoperative lordosis was 43.5degrees (+/- 14.9degrees), average intraoperative lordosis was 48.8degrees (+/- 13.2degrees), average postoperative lordosis was 46.5degrees (+/- 16.1degrees) and the average change on the frame was 5.3degrees (+/- 10.6degrees). RESULTS: Among all patients, 24 patients were diagnosed with simple spinal stenosis, 43 patients with spondylolisthesis (29 degenerative spondylolisthesis and 14 isthmic spondylolisthesis). Between the SS group and spondylolisthesis group, preoperative lordosis, intraoperative lordosis and postoperative lordosis were significantly larger in the spondylolisthesis group. The ratio of patients with increased lordosis on the OSI frame compared to preoperative lordosis was significantly higher in the spondylolisthesis group. The risk of increased lordosis on frame was significantly higher in the spondylolisthesis group (odds ratio, 3.325; 95% confidence interval, 1.101 to 10.039; p = 0.033). CONCLUSIONS: Intraoperative lumbar lordosis on the OSI frame with a prone position was larger in the SS patients than the spondylolisthesis patients, which also produced a larger postoperative lordosis angle after posterior spinal fusion surgery. An increase in lumbar lordosis on the OSI frame should be considered during posterior spinal fusion surgery, especially in spondylolisthesis patients.
Aged ; Aged, 80 and over ; Female ; Humans ; Intraoperative Care/*methods ; Lumbar Vertebrae/*surgery ; Male ; Middle Aged ; Postoperative Complications/*prevention & control ; Posture/physiology ; Prone Position/*physiology ; Retrospective Studies ; Spinal Stenosis/*surgery ; Spondylolisthesis/*surgery

PURPOSE: To investigate the prevalence of paralytic ileus after spinal operation in the supine or prone operative position and to determine the efficacy of prophylactic gastrointestinal motility medications in preventing symptomatic paralytic ileus after a spinal operation. MATERIALS AND METHODS: All patients received spinal surgery in the supine or prone operative position. The study period was divided into two phases: first, to analyze the prevalence of radiographic and symptomatic paralytic ileus after a spinal operation, and second, to determine the therapeutic effects of prophylactic gastrointestinal motility medications (postoperative intravenous injection of scopolamine butylbromide and metoclopramide hydrochloride) on symptomatic paralytic ileus after a spinal operation. RESULTS: Basic demographic data were not different. In the first phase of this study, 27 patients (32.9%) with radiographic paralytic ileus and 11 patients (13.4%) with symptomatic paralytic ileus were observed. Radiographic paralytic ileus was more often noted in patients who underwent an operation in the prone position (p=0.044); whereas the occurrence of symptomatic paralytic ileus was not different between the supine and prone positioned patients (p=0.385). In the second phase, prophylactic medications were shown to be ineffective in preventing symptomatic paralytic ileus after spinal surgery [symptomatic paralytic ileus was observed in 11.1% (4/36) with prophylactic medication and 16.7% (5/30) with a placebo, p=0.513]. CONCLUSION: Spinal surgery in the prone position was shown to increase the likelihood of radiographic paralytic ileus occurrence, but not symptomatic paralytic ileus. Unfortunately, the prophylactic medications to prevent symptomatic paralytic ileus after spine surgery were shown to be ineffective.
Adjuvants, Anesthesia/*administration & dosage/pharmacology ; Adult ; Aged ; Antiemetics/*administration & dosage/pharmacology ; Female ; Gastrointestinal Motility/*drug effects/physiology ; Humans ; Injections, Intravenous ; Intestinal Pseudo-Obstruction/drug therapy/epidemiology/*prevention & control ; Lumbar Vertebrae/radiography/*surgery ; Male ; Metoclopramide/*administration & dosage/pharmacology ; Middle Aged ; Postoperative Complications/epidemiology ; Prevalence ; Prone Position ; Prospective Studies ; Republic of Korea ; Scopolamine Hydrobromide/*administration & dosage/*pharmacology ; Spinal Fusion/*adverse effects ; Supine Position ; Treatment Outcome

This paper is aimed to assess the efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2) and bone marrow stromal cell (BMSCs) composited tricalcium phosphate (TCP) in a rat model of posterolateral lumbar intertransverse process fusion. Rat BMSCs were cultured in vitro. Twenty SD rats underwent single-level bilateral intertransverse process spine arthrodesis at L4 and L5. These rats were assigned to two groups according to the graft materials. They received: 10 of the total were treated with the BMSCs with rhBMP-2 and tricalcium phosphate (TCP) as the experimental group, and the other 10 with TCP treatment alone as the control group. All the animals were killed at 4 weeks after surgery and the spine fusion results were assessed by gross inspection, manual palpation, radiography and histology. The fusion rate, the tensile strength and stiffness of the solidly fused levels in the experimental group were statistically higher than that of the controlled group (P < 0.05). These results showed that the spinal fusion could be improved mechanically when rhBMP-2 and BMSCs were added into the TCP.
Animals ; Bone Morphogenetic Protein 2 ; therapeutic use ; Calcium Phosphates ; therapeutic use ; Cells, Cultured ; Combined Modality Therapy ; Female ; Lumbar Vertebrae ; surgery ; Male ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Osseointegration ; physiology ; Rats ; Rats, Sprague-Dawley ; Recombinant Proteins ; therapeutic use ; Spinal Fusion ; methods ; Transforming Growth Factor beta ; therapeutic use

OBJECTIVETo assess the biomechanical stability of asymmetrical posterior internal fixation for transforaminal lumbar interbody fusion (TLIF) with transfacetopedicular screws (TFPS).

METHODSRange of motion (ROM) testing was performed in 7 fresh-frozen human cadaveric lumbar spine motion segments in flexion/extension, lateral bending, and axial rotation using 10.0 Nm torques at the L3-4 motion segment. The sequential test configurations included intact motion segment, TLIF and ipsilateral pedicle screw (PS), TLIF and ipsilateral PS plus contralateral TFPS according to Boucher technique, and TLIF and bilateral PS. The ROM was determined to assess the construct stability.

RESULTSIn flexion/extension, lateral bending, and axial rotation, no measureable difference was found in the ROM between the standard bilateral pedicle screw and the novel asymmetric posterior internal fixation after TLIF. After TLIF, the ipsilateral PS construct provided less segment stability than the novel asymmetric construct with TFPS in flexion, left bending and left rotation. In rotation, the novel asymmetric construct allowed for significant off-axial rotation motions detrimental to the stability and fusion.

CONCLUSIONIpsilateral PS placement plus contralateral TFPS provides stability comparable to that of TLIF with bilateral PS, and can be an alternative in minimal invasive surgery.

Adult ; Biomechanical Phenomena ; Bone Screws ; Cadaver ; Humans ; Internal Fixators ; Lumbar Vertebrae ; physiology ; surgery ; Male ; Minimally Invasive Surgical Procedures ; instrumentation ; methods ; Range of Motion, Articular ; physiology ; Spinal Fusion ; instrumentation ; methods

OBJECTIVE: To examine the biomechanical effect of lumbar discectomy and disc replacement on compressive load in proximal adjacent segment, to understand the characteristics of the prosthesis and effects in spine after artificial disc replacement (ADR), and to evaluate long-term clinical effect in adjacent segments. METHODS: Complete human cadaveric ligamentous lumbar spine specimens were used to make 3 models: an intact sample, a discectomy sample, and a sample of ADR after the discectomy. The compressive load in proximal segment above the injury segment was measured separately in various loading cases on the 3 models. RESULTS: The changes of intervertebral loads in the adjacent segments made the compressive load increase in the proximal segment after the discectomy. The compressive load in the proximal segment was lower in the ADR group than that in the injury group. There was no significant difference between the ADR group and intact group. CONCLUSION Discectomy increases the compressive load in the proximal segment, while ADR reduces it, showing the same compressive load level with the intact model in the proximal segment. Changes of compressive loading in adjacent level segments after discectomy and ADR, may be the cause of abnormal stress distribution and movements of adjacent segments, and be of benefit for the disc replacement.
Adult ; Biomechanical Phenomena ; Cadaver ; Diskectomy ; methods ; Humans ; Intervertebral Disc ; surgery ; Lumbar Vertebrae ; physiology ; surgery ; Models, Biological ; Prosthesis Implantation ; Weight-Bearing ; physiology

We performed biomechanical comparison of a xenograft bone plate-screw (XBPS) system for achieving cadaveric lumbar transpedicular stabilization (TS) in dogs. Twenty dogs' cadaveric L2-4 lumbar specimens were harvested and their muscles were removed, but the discs and ligaments were left intact. These specimens were separated to four groups: the L2-4 intact group as control (group I, n = 5), the L3 laminectomy and bilateral facetectomy group (LBF) (group II, n = 5), the LBF plus TS with metal plate-screw group (group III, n = 5) and the LBF plus TS with XBPS group (group IV, n = 5). Five kinds of biomechanical tests were applied to the specimens: flexion, extension, left-right bending and rotation. The averages of the 16 stiffness values were calculated and then these were statistically analyzed. The statistical results show that the XBPS system contributes spinal stability and this system can be a good choice for achieving TS.
Animals ; Biomechanics ; Bone Plates/*veterinary ; Bone Screws/*veterinary ; Cadaver ; Dogs ; Lumbar Vertebrae/physiology/*surgery ; Range of Motion, Articular/physiology ; Spinal Fusion/instrumentation/*methods ; Transplantation, Heterologous/instrumentation/*methods