• Journal of Korean Neurosurgical Society
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• v.40 no.6
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• pp.412-418
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• 2006

Objective : The safety of titanium metal cages in tuberculous spondylitis has not been investigated. We evaluated the outcome and complications of titanium mesh cages for reconstruction after thoracolumbar vertebrectomy in the tuberculous spondylitis. Methods : There were 17 patients with 18 operations on the tuberculous spondylitis in this study. Sixteen patients were operated with anterior corpectomy and reconstruction with titanium mesh cage followed by posterior transpedicular screw fixations on same day, two pateints were operated by either anterior or posterior approach only. After the affected vertebral body resection and pus drainage from the psoas muscle, titanium mesh cage, filled with morselized autogenous bone, was inserted. All the patients had antituberculosis medication for 18 months. The degree of kyphosis correction and the subsidence of cage were measured in the 15 patients available at a minimum of 2 years. Outcome was assessed with various cross-sectional outcome measures. Recurrent infection was identified by serial ESR[Erythrocyte Sedimentation Rate] and CRP[Cross Reactive Protein]. Results : There was no complication from the use of a titanium mesh cage. Recurrent infection was not detected in any case. Average preoperative of $9.2^{\circ}$ was reduced to $-2^{\circ}$ at immediate postoperative period, and on final follow up period kyphotic angle was measured to be $4.5^{\circ}$. Postoperatively, subsidence was detected in most patients especially at ambulation period, however further subsidence was prevented by the titanium mesh cage. Osseous union was identified in all cases at the final follow-up. Conclusion : The cylindrical mesh cage is a successful instrument in restoring and maintaining sagittal plane alignment without infection recurrence after vertebrectomy for tuberculous spondylitis.

• Journal of Korean Neurosurgical Society
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• v.41 no.2
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• pp.111-117
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• 2007

Objective : The objective of this study was to validate the effects of a titanium mesh cage and dynamic plating in anterior cervical stabilization after corpectomy. Methods : A retrospective study was performed on 31 consecutive patients, who underwent anterior cervical reconstruction with a titanium mesh cage and dynamic plating, from March 2004 to February 2006. Twenty-four patients had 1-level and 7 had 2-level corpectomies. Ten patients underwent surgery with a cage of 10-mm diameter and 21 with 13-mm diameter. Neurological status and outcomes were assessed according to Odom's criteria. Sagittal angle, coronal angle, settling ratio, sagittal displacement, and cervical lordosis were used to evaluate the radiological outcomes. Results : In overall, 26 [83.9%] of 31 showed excellent or good outcomes. Thirteen percent [4 cases] of the patients developed surgical complications, such as hoarseness, transient dysphagia, or nerve root palsy. Seven [22.6%] patients had reconstruction failure:5 [20.8%] in the 1-level corpectomy group and 2 [28.5%] in the 2-level corpectomy group. Revisions were required in 2 patients with plate pullout due to significant instability. However, none of 5 patients who demonstrated cage displacement or screw pullout, underwent a revision. Radiographs revealed bony consolidation in 96.3% of the patients, including 6 patients with implantation failure during the follow-up period. Conclusion : Based on our preliminary results, the titanium mesh cage and dynamic plating was effective for cervical reconstruction after corpectomy. The anterior cervical reconstruction performed with dynamic plates is considered to reduce stress shielding and greater graft compression that is afforded by the unique plate design.

• Journal of Korean Neurosurgical Society
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• v.30 no.8
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• pp.998-1003
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• 2001

Objective : The maintenance of the correction of kyphotic deformity is one of the difficult problem in tuberculous spondylitis after anterior debriment and fusion with tricortical bone graft. The goal of this study is to find out the efficacy of titanium mesh cage impacted with autogenous bone chip in tuberculous spondylitis treated with anterior intervertebral fusion. Materials and Method : Twelve patients were treated with anterior intervertebral fusion using titanium mesh cage for tuberculous spondylitis from January 1996 to June 1999. We analized the changes in the correction of kyphotic deformity, changes of ESR and CRP, fusion state and recurrence after anterior intervertebral fusion with titanium mesh cage. Results : Clinical symptoms were improved in all twelve patients without any neurologic complications. The mean kyphotic angle corrected was 7.3 degrees immediately after operation, but the loss of correction of kyphotic angle was 2.2 degrees after 3 months and 2.6 degrees after 6 months. We found that the loss of correction of kyphotic deformity occurred mainly within the first 3 months after surgery. Only one patient, suffered from acute hepatic failure after first operation and had an insufficient anti-tuberculous medication therapy, showed recurrence of tuberculous spondylitis after 6 months. The patient underwent a second operation with posterior fixation procedure with good outcome. The changes of ESR and CRP were not specifically important factor to reveal recurrence of tuberculosis of the spine in our series. Conclusion : The surgical procedure of tuberculous spondylitis using titanium mesh cage with bone chip seems to be an effective procedure to minimize loss of the correction of kyphotic deformity without any aggravating inflammatory change and recurrence with titanium mesh cage, when sufficient debridement and anti-tuberculous chemotherapy are achieved.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.348-356
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• 2011

Objective : The safety and efficacy of various fusion substitutes in pyogenic osteomyelitis has not been investigated. We evaluated and compared the cadaveric allograft and titanium cages used to reconstruct, maintain alignment and achieve fusion in the management of pyogenic spinal infection. Methods : There were 33 patients with pyogenic osteomyelitis underwent fusion in this study. Fifteen of the 33 patients were operated on by fusion with allografts (cadaveric patella bones) and 18 of those were operated with titanium mesh cages filled with autologous cancellous iliac bone. After the affected disc and vertebral body resection with pus drainage, cadaveric allograft or titanium cages were inserted into the resected space. Posterior transpedicular screw fixation and rod compression in resected space, where cadaveric allograft or titanium cages were inserted, was performed to prevent the malposition in all patients except in 1 case. Recurrent infection was identified by serial erythrocyte sedimentation rate and cross reactive protein follow-up. Osseous union and recurred infection available at a minimum of 2 years following operation was identified. The amount of kyphosis correction and the subsidence were measured radiographically. Results : Spinal fusion was achieved in 29 of 33 patients. In the cadaveric allograft group, 93.3% of patient (14 of 15) showed the osseous union while 83.3% of patient (15 of 18) in the titanium cage group showed union. Subsidence was noted in 12 of the patients. Twelve patients (36.3%) showed unsettling amounts of subsidence postoperatively whereas 46.6% of patients in the cadaveric allograft group and 37.7% of patients in the titanium cage group showed similar subsidence, respectively. There were statistical difference in the fusion rate (p=0.397) and subsidence rate (p=0.276) between the two groups. There was significant statistical difference in the postoperative improvement of segmental kyphosis between the two groups (p=0.022), that is the improvement in sagittal alignment was greater in the titanium cage group than in the cadaveric allograft group. There was no case of recurred infection. Conclusion : The cadaveric allograft and titanium cages are effective and safe in restoring and maintaining sagittal plane alignment without increased incidence in infection recurrence in pyogenic osteomyelitis. The postoperative improvement of segmental kyphosis was better in the cage group.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.357-362
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• 2011

Objective : To report our experience with pyogenic spondylitis treated with anterior radical debridement and insertion of a titanium mesh cage and to demonstrate the effectiveness and safety of the use of a titanium mesh cage in the surgical management of pyogenic spondylitis. Methods : We retrospectively analyzed the clinical characteristics of 19 patients who underwent surgical treatment in our department between January 2004 and December 2008. The average follow-up period was 11.16 months (range, 6-64 months). We evaluated risk factors, cultured organisms, lab data, clinical outcomes, and radiographic results. Surgical techniques for patients with pyogenic spondylitis were anterior radical debridement and reconstruction with titanium mesh cage insertion and screw fixation. All patients received intravenous antibiotics for at least 6 weeks postoperatively, and some patients received oral antibiotics. Results : The infections resolved in all of the patients as noted by normalization of their erythrocyte sedimentation rates and C-reactive protein levels. The mean pain score on a Visual Analog Scale was 7.8 (range, 4-10) before surgery and 2.4 (range, 1-5) after surgery. The Frankel grade was improved by one grade in seven patients. After surgery, the average difference of the angle was improved about $6.96^{\circ}$ in all patients. At the last follow-up, the mean loss of correction was $4.86^{\circ}$. Conclusion : Anterior radical debridement followed by the placement of instrumentation with a titanium mesh cage may be a safe and effective treatment for selected patients with pyogenic spondylitis. This surgical therapy does not lead to recurrent pyogenic spondylitis.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.300-308
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• 2001

Objectives : Anterior cervical discectomy and interbody fusion has become a well-accepted surgical treatment of degenerative cervical diseases. Implatable cages have a stabilizing effect without plates and no need for autogenous bone graft. The authors evaluates the effect of implatable titanium cage(RABEA) on the clinical and radiological outcomes. Methods : 34 patients with symptomatic cervical degenerative diseases due to one level disc pathology were underwent anterior cervical discectomy and interbody fusion with titanium cages(RABEA) which were not filled with cancallous bone grafts from January 1999 to May 2001. Patients with osteoporosis and older than 65 years were not included. Among them, 15 patients could be followed-up for at least 1 year. The authors retrospectively reviewed the charts and radiographic data. Mean follow-up period was $1.3{\pm}0.2years$. Results : Clinical results according to the Odom's criteria was exellent and good in 14(93%) patients. One patient with fair result showed complete loss of the disc space height due to settlement of the cage. Preoperatively, the mean height of the disc space(${\pm}$standard deviation) was $3.42{\pm}1.10mm$(range 2.0-5.5mm), and at 1 day postoperatively it was $7.88{\pm}0.90mm$(range 6.50-9.0). The mean height of the disc space after 1 year was $6.50{\pm}1.38mm$(range 3.0-8.0). The restoration of the height was statistically significant(p<0.05). The mean height after 1 year was $82.7{\pm}15.9%$ of the height at 1 day postoperatively. Preoperatively the mean value of the cervical lodortic angle was $21.8{\pm}11.8^{\circ}$ and 1 year postopertively, it was $24.5{\pm}8.3^{\circ}$, which was statistically not significant. All patients showed no abnormal movements on flexion and extension lateral film after 6 months. Conclusion : Implantable titanium cages appear safe and effective in selected patients, and their use helps to avoid complications associated with bone graft harvest. Subsidence of the cage seems to be a potential risk factor for recurrence of the symptoms. For long-term results, a longer follow-up is required.

• Journal of Biomedical Engineering Research
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• v.40 no.5
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• pp.158-164
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• 2019

The interbody fusion cage used to replace the degenerative intervertebral disc is largely composed of titanium-based biomaterials and biopolymer materials such as PEEK. Titanium is characterized by osseointergration and biocompatibility, but it is posed that the phenomenon such as subsidence can occur due to high elastic modulus versus bone. On the other hand, PEEK can control the elastic modulus in a similar to bone, but there is a problem that the osseointegration is limited. The purpose of this study was to implement titanium material's stiffness similar to that of bone by applying cellular structure, which is able to change the stiffness. For this purpose, the cellular structure A (BD, Body Diagonal Shape) and structure B (QP, Quadral Pod Shape) with porosity of 50%, 60%, 70% were proposed and the reinforcement structure was suggested for efficient strength reinforcement and the stiffness of each model was evaluated. As a result, the stiffness was reduced by 69~93% compared with Ti6Al4V ELI material, and the stiffness most similar to cortical bone is calculated with the deviation of about 12% in the BD model with 60% porosity. In this study, the interbody fusion cage made of Ti6Al4V ELI material with stiffness similar to cortical bone was implementing by applying cellular structure. Through this, it is considered that the limitation of the metal biomaterial by the high elastic modulus may be alleviated.

• Fibers and Polymers
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• v.4 no.2
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• pp.89-96
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• 2003

A vertebral cage is a hollow medical device which is used in spine forgery. By implanting the cage into the spine column, it is possible to restore disc and relieve pressure on the nerve roots. Most cages have been made of titanium alloys but they detract the biocompatibility. Currently PEEK (polyether ether ketone) if applied to various implants because it has good properties like heat resistance, chemical resistance, strength, and especially biocompatibility. A new shape of vertebral cage is designed and injection molding of PEEK is considered for production. Before injection molding of the cage, it is needed to evaluate process conditions and properties of the final product. Variables affecting the shrinkage of the cage are considered, e.g., injection time, packing pressure, mold temperature, and melt temperature. By using the numerical simula-tion program, MOLDFLOW, several cases are studied. Data files obtained by MOLDFLOW analysis are used for stress anal-ysis with ABAQUS, and shrinkage and residual stress fields are predicted. With these results, optimum process conditions are determined.

• Composites Research
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• v.25 no.4
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• pp.98-104
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• 2012

In recent years, degenerative spinal instability has been effectively treated with a cage. However, little attention is focused on the stiffness of the cage. Recent advances in the medical implant industry have resulted in the use of medical carbon fiber reinforced polymer (CFRP) cages. The biomechanical advantages of using different cage material in terms of stability and stresses in bone graft are not fully understood. A previously validated three-dimensional, nonlinear finite element model of an intact L2-L5 segment was modified to simulate posterior interbody fusion cages made of CFRP and titanium at the L4-L5 disc with pedicle screw, to investigate the effect of cage stiffness on the biomechanics of the fused segment in the lumbar region. From the results, it could be found that the use of a CFRP cage would not only reduce stress shielding, but it might also have led to increased bony fusion.

• Journal of Korean Neurosurgical Society
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• v.56 no.4
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• pp.323-329
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• 2014

Objective : Vertebral body replacement following corpectomy in thoracic or lumbar spine is performed with titanium mesh cage (TMC) containing any grafts. Radiological changes often occur on follow-up. This study investigated the relationship between the radiological stability and clinical symptoms. Methods : The subjects of this study were 28 patients who underwent corpectomy on the thoracic or lumbar spine. Their medical records and radiological data were retrospectively analyzed. There were 23 cases of tumor, 2 cases of trauma, and 3 cases of infection. During operation, spinal reconstruction was done with TMC and additional screw fixation. We measured TMC settlement in sagittal plane and spinal angular change in coronal and sagittal plane at postoperative one month and last follow-up. Pain score was also checked. We investigated the correlation between radiologic change and pain status. Whether factors, such as the kind of graft material, surgical approach, and fusion can affect the radiological stability or not was analyzed as well. Results : Mean follow-up was 23.6 months. During follow-up, $2.08{\pm}1.65^{\circ}$ and $6.96{\pm}2.08^{\circ}$ of angular change was observed in coronal and sagittal plane, respectively. A mean of cage settlement was $4.02{\pm}2.83mm$. Pain aggravation was observed in 4 cases. However, no significant relationship was found between spinal angular change and pain status (p=0.518, 0.458). Cage settlement was seen not to be related with pain status, either (p=0.644). No factors were found to affect the radiological stability. Conclusion : TMC settlement and spinal angular change were often observed in reconstructed spine. However, these changes did not always cause postoperative axial pain.