Anterior Spinal Fixation Research Articles

Surgical Outcomes of Adults with Spinal Caries from 1992 to 2019: A Single-Center Study-Risk Factors for the Progression of Kyphosis after Anterior Spinal Fixation Reveal Cases Needing Additional Posterior Instrumentation.

Background: This study aims to investigate the postoperative improvement of paralysis, fusion rate and risk factors for kyphosis progression in adults affected with spinal caries. Methods: Overall, 134 patients with spinal caries from the thoracic to lumbar spine from 1992 to 2021 were included in this study. Data concerning the affected level (thoracic, thoracolumbar, lumbar, and lumbosacral), bone fusion rate, and progression of the postoperative local kyphosis angle were collected. The risk factors for the progression of local kyphosis angle after anterior spinal fixation (ASF) were determined using linear regression analysis. Results: Preoperatively, the degree of spinal cord paralysis was D and E on Frankel classification. Improvement of paralysis was good with surgery, especially from C, D. The overall bone fusion rate was 83.2%. The only factor influencing the progression of local kyphosis angle after ASF was the level of the affected vertebra. Progression of kyphosis angle after ASF was very advanced in the thoracolumbar transition area. Conclusions: Surgical improvement in paraplegia and the fusion rate of ASF with only grafted bone was good. However, in patients affected in the thoracolumbar spine region, posterior instrumentation is desirable because of local kyphosis progression risk after surgery.

Risk factors for early mortality in elderly patients with unstable isolated C2 odontoid fracture treated with halo-vest or surgery

The aim of this study was to compare in-hospital mortality of three procedures –halo-vest immobilization, anterior spinal fixation (ASF), and posterior spinal fixation (PSF)– in the treatment of elderly patients with isolated C2 odontoid fracture. We extracted data for elderly patients who were admitted with C2 odontoid fracture and treated with at least one of the three procedures (halo-vest immobilization, ASF, or PSF) during hospitalization. We conducted a generalized propensity score-based matching weight analysis to compare in-hospital mortality among the three procedures. We further investigated independent risk factors for in-hospital death. The study involved 891 patients (halo-vest, n = 463; ASF, n = 74; and PSF, n = 354) with a mean age of 78 years. In-hospital death occurred in 45 (5.1%) patients. Treatment type was not significantly associated with in-hospital mortality. Male sex (odds ratio 2.98; 95% confidence interval 1.32–6.73; p = 0.009) and a Charlson comorbidity index of ≥ 3 (odds ratio 9.18; 95% confidence interval 3.25–25.92; p < 0.001) were independent risk factors for in-hospital mortality. In conclusion, treatment type was not significantly associated with in-hospital mortality in elderly patients with isolated C2 odontoid fracture. Halo-vest immobilization can help to avoid adverse events in patients with C2 odontoid fracture who are considered less suitable for surgical treatment.

Impact of the Cage Height, Diameter, and Positioning on Clinical and Radiographic Outcome of the Extreme Lateral Interbody Fusion

Introduction Extreme lateral interbody fusion (ELIF) is a novel technique for anterior spinal fixation and indirect decompression of neural elements. The aim of this study was to determine certain parameters of the interbody cage that would result in better radiographic and clinical outcomes. Patients and Methods We performed a retrospective analysis of 145 ELIFs in 90 patients. Intervertebral disc height, foraminal height, cage position, and lumbar lordosis were determined on preoperative, postoperative, and the latest follow-up studies. Clinical outcomes were evaluated by Oswestry Disability Index and Visual Analogue Scale. Results At the time of last follow-up (17.7 ± 1.1 months), two of the following factors determined restoration of foraminal height: the amount of increase in the disc height (implant height—preoperative disc height) and the footprint of the intervertebral spacer. Cages that had increased the disc height by 6 to 9 mm yielded in significantly greater restoration of foraminal height compared with the grafts that had increased the disc height by 0 to 3 mm ( p &lt; 0.01) or 3 to 6 mm ( p &lt; 0.05). In addition, 22 mm spacers allowed for a significantly higher increase in the foraminal height compared with 18 mm spacers ( p &lt; 0.001). Interestingly, neither cage position nor posterior instrumentation had statistically significant influence on restoration of foraminal height. Both, lordotic and nonlordotic cages allowed for increased lumbar lordosis on postoperative imaging. Clinical evaluation revealed a mean ODI, VAS back, buttock, and leg pain improvements of 21.1%, 3.7, 3.6, and 3.7 points, respectively. Conclusions In ELIF, cage width and height but not cage position, determine restoration of foraminal height.

Biomechanical testing of a unique built-in expandable anterior spinal internal fixation system.

BackgroundExpandable screws have greater pullout strength than conventional screws. The purpose of this study was to compare the biomechanical stability provided by a new built-in expandable anterior spinal fixation system with that of 2 commonly used anterior fixation systems, the Z-Plate and the Kaneda, in a porcine partial vertebral corpectomy model.MethodsEighteen porcine thoracolumbar spine specimens were randomly divided into 3 groups of 6 each. A vertebral wedge osteotomy was performed by removing the anterior 2/3 of the L1 vertebral body and the T15/L1 disc. Vertebrae were fixed with the Z-Plate, Kaneda, or expandable fixation system. The 3-dimensional spinal range of motion (ROM) of specimens in the intact state (prior to osteotomy), injured state (after osteotomy), and after internal fixation were recorded. The pullout strength and maximum torque of common anterior screws, the expandable anterior fixation screw unexpanded, and the expandable anterior fixation screw expanded was tested.ResultsAfter internal fixation, the expandable device and Z-plate system exhibited higher left bending motion than the Kaneda system (5.50° and 5.37° vs. 5.04, p = 0.001 and 0.008, respectively), and the Z-plate and Kaneda groups had significantly higher left axial and right axial rotation ROM as compared to the expandable device group (left axial rotation: 5.23° and 5.02° vs. 4.53°; right axial rotation: 5.23° and 5.08° vs. 4.49°). The maximum insertion torque of the expandable device was significantly greater than of a common screw (5.10 vs. 3.75 Ns). The maximum pullout force of the expandable device expanded was significantly higher than that of the common screw and the expandable device unexpanded (3,035.48 N vs. 1,827.38 N and 2,333.49 N).ConclusionsThe built-in anterior fixation system provides better axial rotational stability as compared to the other 2 systems, and greater maximum torque and pullout strength than a common fixation screw.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-424) contains supplementary material, which is available to authorized users.

The Impact of the Cage Height, Diameter and Positioning on Clinical and Radiographic Outcome of the Extreme Lateral Interbody Fusion

IntroductionExtreme lateral interbody fusion (ELIF) is a novel technique for anterior spinal fixation and indirect decompression of neural elements. The aim of this study was to determine certain p...

The Impact of the Cage Height, Diameter, and Positioning on Clinical and Radiographic Outcome of the Extreme Lateral Interbody Fusion

Introduction Extreme lateral interbody fusion (ELIF) is a novel technique for anterior spinal fixation and indirect decompression of neural elements. Materials and Methods Retrospective analysis of 145 ELIFs in 90 patients. Cages measuring 8 to 14 mm in height were used. Intervertebral disc height, foraminal height, cage position, and lumbar lordosis were determined on preoperative, postoperative, and the latest follow-up studies. Clinical outcomes were evaluated by Oswestry disability index (ODI) and visual analog scale (VAS). Results At the time of last follow-up (17.7 ± 1.1 months), two factors determined restoration of foraminal height: First, the amount of oversizing the graft (implant height-preoperative disc height) showed a significant positive correlation with increase of foraminal height (Pearson correlation coefficient 0.691, p &lt; 0.001). Implantation of cages 6 to 9 mm higher than the preoperative disc resulted in 3.1 ± 0.3 mm foraminal height increase. Thus, cages oversized by 6 to 9 mm yielded in significantly greater restoration of foraminal height compared with grafts that were oversized by 0 to 3 mm ( p &lt; 0.01) or 3 to 6 mm ( p &lt; 0.05). The second determinant of foraminal height restoration was the footprint of the intervertebral spacer. Approximately one half of our patients received 18 mm spacers and the other 22 mm grafts. Eighteen mm spacers allowed for a 2.1 mm increase of foraminal height while 22 mm spacers lead to an increase by 4.0 mm on postoperative radiographs ( p &lt; 0.001). Interestingly, neither cage position nor posterior instrumentation had statistically significant influence on restoration of foraminal height. ELIF interbody grafts provided adequate anterior column support with 1.0 ± 0.1 mm subsidence on last follow-up imaging compared with immediate postoperative studies. Subsidence was significantly greater with intervertebral cages that were oversized by 0 to 3 mm (1.7 ± 0.5 mm) compared with cages oversized by 6 to 9 mm (0.8 ± 0.2 mm, p &lt; 0.05). One-third of patients received lordotic spacers. Both, lordotic and nonlordotic cages allowed for increased lumbar lordosis on postoperative imaging (6.0 and 4.7 degrees, respectively). Clinical evaluation revealed a mean ODI, VAS back, buttock, and leg pain improvements of 21.1%, 3.7, 3.6, and 3.7 points, respectively. Conclusion In ELIF, cage width and height but not cage position determine restoration of foraminal height. Thus, optimum foraminal height restoration is achieved by using 22 mm wide cages oversized by 6 to 9 mm in height. Disclosure of Interest None declared

Migration of Anterior Spinal Rod From the Dorsolumbar Spine to the Knee

A retrospective case report. The objective of the present article is to report an unusual complication of spinal instrumentation. Migration of spinal implants to distant site is quite unusual, and literature till date has only 2 case reports. For the first time, we are reporting a case of anterior spinal rod migration from the dorsolumbar spine to the knee joint in a young male patient after 4 years of its fixation following spinal injury. A 38-year-old man presented with pain, swelling, and restriction of movement of left knee joint. On clinical examination, a hard movable rod was palpable which was suspected to be a metallic foreign body initially. The detailed history of the patient revealed anterior spinal fixation following posttraumatic injury of L1 vertebra 4 years back. Radiograph showed a metallic rod lying around the knee joint with absence of anterior rod of dorsolumbar spine. The suspicion of migration of the rod was confirmed by surgical exploration. After 1 week of removal of the rod, patient became totally asymptomatic with normal full range of movement of the knee joint. Though rare, migration of implants from the spine to the distant sites is always a possibility and may have severe complications too. We stress the need of long-term follow-up with clinical examination and radiographs to prevent missing such a complication.

Pseudoaneurysm of the thoracoabdominal aorta caused by a severe migration of an anterior spinal device

Background Context Case report. Purpose To describe the case of pseudoaneurysm of the thoracoabdominal aorta caused by the severe migration of an anterior spinal device 5 years after surgery. Study Design/Setting Case report. Methods A 70-year-old woman was referred to us because of migrated anterior spinal devices and a pseudoaneurysm of the thoracoabdominal aorta. This patient had undergone anterior corpectomy and spinal fusion from Th12 to L2 because of delayed palsy after a burst fracture using a smooth rod Kaneda device (SRK) with bioactive ceramic (apatite-wollastonite containing glass ceramic) at a local hospital. She had persistent low back pain after the surgery. Results Five years after the initial surgery, the patient was referred to us because of increasing of her low back pain and the migrated SRK devices shown on plain X-ray films. An enhanced computed tomography scan taken in our hospital clearly showed a pseudoaneurysm of the thoracoabdominal aorta surrounding the SRK devices. The pseudoaneurysm was resected, the aortic defect was repaired with an artificial patch, and the migrated SRK devices were removed. Conclusions The pseudoaneurysm of the aorta can occur secondary to a migrated anterior spinal fixation device and can be successfully treated by revision anterior surgery with vascular repair and implant removal.

Influence of Screw Positioning in a New Anterior Spine Fixator on Implant Loosening in Osteoporotic Vertebrae

A biomechanical study was designed to assess implant cut-out of three different angular stable anterior spinal implants. Subsidence of the implant relative to the vertebral body was measured during an in vitro cyclic loading test. The objective of the study was to evaluate two prototypes (Synthes) of a new anterior spine fixator with different screw angulations in comparison to the established MACSTL(R) Twin Screw Concept (Aesculap). The influence of factors like load-bearing cross-sectional area, screw angulation and bone mineral density upon implant stability should be investigated. Epidemiologic data predict a growing demand for appropriate anterior spinal fixation devices especially in patients with inferior structural and mechanical bone properties. Although different concepts for anterior spinal instrumentation systems have been tried out, implant stability is still a problem. Three angular stable, anterior spinal implants were tested using 24 human lumbar osteoporotic vertebrae (L1-L5; age 84 (73-92)): MASC TL system (Aesculap); prototype 1 (MP1) with 18 degrees and prototype 2 (MP2) with 40 degrees screw angulation (both Synthes). All implants consisted of two screws with different outer screw diameters: 7-mm polyaxial screw with 6.5-mm stabilization screw (MASC TL), two 5-mm locking-head screws each (MP1 and MP2). Bone mineral density (BMD) and vertebral body width of the three specimen groups were evenly distributed. The specimens were loaded in craniocaudal direction (1Hz) for 1000 cycles each at three consecutive load steps; 10-100 N, 10-200 N and 10-400 N. During cyclic loading subsidence of the implant relative to the vertebral body was measured in the unloaded condition. Cycle number at failure (defined as a subsidence of 2 mm) was determined for each specimen. A survival analysis (Cox Regression) was performed to detect differences between implant groups at a probability level of 95%. High correlations were found between BMD and number of cycles until failure (MP1; r = 0.905, P = 0.013; MP2: r = 0.640, P = 0.121; MACS TL: r = 0.904, P = 0.013) and between load bearing cross sectional area and number of cycles until failure (MP1: r = 0.849, P = 0.032;MP2: r = 0.692, P = 0.085; MACS TL: r = 0.902, P = 0.014). Both Prototypes survived significantly longer than the MACS TL implant (MP1: P = 0.012, MP2: P = 0.014). The survival behaviour of MP1 and MP2 was not significantly different (P = 0.354). Implant stability within each implant group was influenced by BMD and load bearing cross-sectional area. The angulation of the two screws did not have a significant influence on cut-out. As conclusion from this study, promising approaches for further implant development are: 1) increase of load-bearing cross-sectional area (e.g., larger outer diameter of the anchorage device), 2) screw positioning in areas of higher BMD (e.g., opposite cortex, proximity to pedicles or the endplates).

Tratamiento quirúrgico de la espondilodiscitis en la espondilitis anquilosante. Presentación de dos casos

Spondylodiscitis in ankylosing spondylitis has a prevalence of 5%. Mechanical and inflammatory factors are involved in its pathogenesis. Neurosurgical operation is required when neurological complications or vertebral instability occur. Surgery is complicated by the increased fragility of the vertebral column, advanced stage of the disease in many patients, and serious pulmonary complications. We report two patients who had had ankylosing spondylitis for over 20 years. Both presented complaining of symptoms for several months with lumbar pain and signs of spinal cord lesions. There were signs of discitis and destruction of the adjacent vertebral bodies at T11 T12 and T12 L1 on imaging investigations of the first and second patient respectively. In both cases an anterior approach was used for discectomay and resection of the adjacent vertebral plates. Then an autologous rib graft was done, and anterolateral fixation with plate and screws to the adjacent vertebral bodies. The patients condition improved. Their pain and previous clinical neurological disorder had disappeared by 5 and 1 year later. The prevalence of patients operated on for spondylodiscitis in the context of ankylosing spondylitis is not known. Dorsolumbar pain with inflammatory characteristics of recent onset in patients with chronic ankylosing spondylitis should lead to suspicion of spondylodiscitis. Although it may be related to previous trauma, discitis is the fundamental mechanism. MR is the most sensitive imaging technique. There may be marked osteoporosis and stenosis of the vertebral canal together with marked ossification of all the paraspinal ligaments. This hinders the approach to the vertebral bodies and their subsequent fixation. Decompression of the vertebral canal using an anterior approach (thoracotomy or thoraco phreno laparotomy) and anterior spinal fixation is the treatment of choice in cases with neurological involvement or involvement of the anterior and medial columns of Denis.

胸椎および腰椎への instrumentation surgery

<Objective> The authors conducted a study to evaluate the clinical outcome of 21 patients in whom thoracolumbar spinal instrumentation surgery was used. <Methods> The study group was composed of 11 men and 10 women with the mean age being 43 years (range 19-73 years). The diagnosis was spinal trauma in 14 patients; metastatic spinal tumor in 4; and infectious disease in 3. The affected level was midthoracic in 8 patients, thoracolumbar in 12, and lumbar in one. Anterior spinal fixation was carried out in 13 patients using Kaneda device in six, and Z-plate in seven. Posterior spinal fixation was performed in eight patients using Texas Scottish Rite Hospital (TSRH) system. Solid bony fusion was achieved in all patients who received autologous bone transplantation. Good neurological outcome was obtained in 18 of 21 patients independently of whether the fixation was by anterior or posterior instrumentation. The 3 patients who had sustained complete spinal cord injury didn't recover neurologically. Radiographical recovery of kyphosis using Kaneda device, Z-plate and TSRH were obtained to the extent of 9 degrees, 3 degrees and 1 degree, respectively. One patient with posterior instrumentation developed deep wound infection. The infection was cured after total removal of the instrument and intravenous antibiotic therapy. <Conclusion> Anterior instrumentation fixation was superior to posterior fixation in radiographical recovery of kyphosis in midthoracic lesions. There were no differences in bony fusion rate and neurological outcome between anterior and posterior fixation.

A Transpedicularly Implanted Anterior Spinal Support

This article describes a device that has been developed to augment posterior spinal fracture fixation by providing support for the anterior column of the spine. The device is contracted for insertion through the limited opening provided by the transpedicular approach to the vertebral body. Once in situ it is configured to support physiological loads. In this way the structural limitations of posterior instrumentation and the surgical difficulties of anterior spinal fixation instrumentation are overcome. A preliminary investigation of the new device together with in vitro studies of a prototype are described in this report. In vitro tests to determine the expansion characteristics and structural performance of the device were performed together with tests to determine the efficacy of the support to reduce loading on the posterior fixation device. It is shown that the device has the necessary expansion characteristics and can support physiological loads without failure. Tests using porcine vertebral columns with a simulated vertebral fracture showed a significant reduction in load carried by the posterior fixation plates (44 +/- 16%) when the anterior support was included in the construct. In addition, the difference in loading between the left and right plates was significantly reduced (81 +/- 12%).

One-stage internal fixation and anterior fusion in complex cervical spinal disorders

The authors describe their experience with the Morscher titanium cervical plate with cancellous locking screws in the management of complex cervical spine disorders. Fifty patients (32 males and 18 females) with a mean age of 54 years (range 10 to 84 years) underwent anterior spinal fixation that extended two to five vertebral bodies, using a titanium cervical plate and autogenous bone graft. Surgeries were performed for a variety of reasons: one for a congenital lesion, five for spinal neoplasms, nine for trauma, and 35 for degenerative arthritides. Ten patients had symptomatic kyphoses due to previous laminectomy, failed anterior surgery, or trauma. Satisfactory fixation and fusion with no neurological deterioration was obtained in all but two cases. Specific complications included six cases of dysphagia, one of sepsis, one of Horner's syndrome, and one case in which the patient had a fatal myocardial infarction the night after surgery. At the end of the follow-up period, fusion was found to have occurred in all remaining cases with no outstanding implant-related problems.

Anterior Spinal Fixators

In vitro calf spine testing was performed in flexion, rotation, and axial load, using a vertebral body corpectomy and anterior iliac crest bone grafting model. Anterior spinal fixation devices then were sequentially tested, and axial stiffness, torsional stiffness, and flexural strain determined. The constructs tested were the Contoured Anterior Spinal Plate (CASP), the Kaneda device, the Kostuik-Harrington device (KH), and the Texas Scottish Rite Hospital (TSRH) vertebral body screw construct. In torsion, the Kaneda device returned spinal stability to that of the intact spine. The Kostuik-Harrington device was unstable in torsion. In axial loading and flexion, the Kaneda device and the TSRH construct proved the most stiff, with the KH and CASP systems significantly lower in stiffness. The authors believe that the Kaneda device and the TSRH vertebral body screw construct are effective in restoring acute stability to the lumbar spine after corpectomy.

Anterior spinal fixation after lumbar corpectomy. A study in dogs.

An animal model was developed to simulate an unstable lumbar burst fracture that had been treated with corpectomy. A fifth lumbar laminectomy, partial facetectomy, and corpectomy was performed in twenty-one dogs. In seven dogs (the control group), a biodegradable polymer spacer was used to create a definite failure of fusion (Group I). Seven dogs were treated with a traditional anterior arthrodesis with an autogenous ulnar strut and without instrumentation (Group II). The remaining seven dogs were treated with an ulnar strut and anterior Kaneda instrumentation that was of an appropriate size for the dog (Group III). At twenty-four weeks, the results were analyzed in terms of the rate of fusion, biomechanical rigidity, neuropathological findings, and histomorphometric data on the vertebral response. The rate of fusion was significantly higher in Group III, in which the Kaneda device had been used, than it was in either Group I or Group II, in which instrumentation had not been used. Biomechanically, the spines in Group III were stiffer in torsion than those in Group I or II. There was no difference between groups in terms of the number of neuropathological changes in the spinal cord. Histomorphometric analysis showed that no meaningful device-related osteopenia occurred in the vertebrae that were spanned by the fixation device. Trabecular density was increased in the vertebrae in which the instrumentation was anchored.

The Syracuse I-Plate

The Syracuse I-Plate is a versatile neutralization plate for anterior spinal fixation following decompression for burst fractures and pathologic vertebral body destruction by tumor. In this article, the history, current use, and indications are discussed. The anterior approach and application of the I-plate to the lower thoracic and lumbar spine is presented, as well as a brief summary of a current clinical series of 34 patients. Fusion rates were high and hardware failure most frequent in patients with associated osteoporosis or extensive posterior disruption, such that the device was contraindicated in cases of extensive three-column injuries or significantly osteoporotic bone.

Comparative Strength of Anterior Spinal Fixation with Bone Graft or Polymethylmethacrylate

In 23 dogs, polymethylmethacrylate (PMMA) was safely implanted in the region of the spinal cord. The dogs were treated by bone or cement fixation after anterior excision of a single cervical vertebral body. Fixation was compared at 0-18 weeks, with control values obtained from 11 dogs. Anterior cement fixation did not displace after 18 weeks. The anterior bone graft appeared to achieve adequate fixation strength around six weeks. The strength of the bone-graft fixation increased, while that of cement fixation decreased somewhat with time. At all time intervals, the ratio of energy absorption to structural failure was somewhat higher with bone graft than with PMMA.