Low-cost 3D modeling software for generating patient-specific drill guide templates for cervical pedicle screw insertion: An in vitro study

BACKGROUND@#Instrumented posterior cervical spine surgery (IPCSS) can be conducted using screws inserted through the pedicles of the vertebra. A safe IPCSS method uses 3D-printing to produce templates that will serve as drill guides for screw placement.@*OBJECTIVES@#This study describes the generation of 3D-printed drill guides using low-cost general purpose 3D modeling software and the comparison of screw insertion accuracy scores against the traditional landmark method and guides created using commercial grade software.@*METHODS@#Twenty-five (25) subaxial pedicles of five cadaveric spines were selected and scanned using computed tomography (CT). A digital reconstruction of the five cadaveric spines were created based on the CT DICOM data. A low-cost 3D modeling software, Rhinoceros 3D, was utilized for trajectory planning and generation of a patientspecific drill template using the digital reconstruction. The templates were then fabricated in ABS plastic using a fused deposition modeling (FDM) 3D printer. Insertion of cervical pedicle screws on the cadaveric spines was done by an orthopedic resident using the 3D printed guides. Postoperative CT scans were obtained, and placement accuracy of the screws were scored by two assessors utilizing a four-point rating system. Screws in correct placement were scored Grade 0 while misplaced screws with neurovascular damage were given a score of Grade 3.@*RESULTS@#Accuracy scores for the 3D-printed drill guides were 52% for assessor 1 and 44% for assessor 2. For assessor 1, screw placement in C3, C6, and C7 received the highest scores. For assessor 2, the highest scores were achieved in C3 and C7. The hybrid method of Bundoc et al. achieved scores of 94% while 3D printed guides utilizing commercial software like Materialise Mimics, Geomagic Freeform, or UG Imageware achieved scores of 80-100%. The traditional landmark method had scores ranging from 12% to 94% depending on the skill of the surgeon.@*CONCLUSION@#Commercial medical 3D image-based engineering software has high acquisition costs that might be beyond the reach of most institutions. A sub-$1000 general purpose 3D modeling software can be used to create drill templates. Several factors were identified in the design and fabrication of the template that can be addressed to increase accuracy. Trajectory planning can also be improved by automating the process. The researchers recommend further studies in these areas specially in the context of developing 3D printing as a support service for surgical operations in the Philippines.

Development of a Patient-specific Guide for High Cervical Spine Fixation / Desenvolvimento de um guia paciente-específico para fixação de coluna cervical alta

Abstract Objective High cervical spine fixation represents a challenge for spine surgeons due to the complex anatomy and the risks of vascular and medullar injury. The recent advances in 3-D printing have unfolded a whole new range of options for these surgeons. Methods In the present study, a guide for the placement of the lateral mass screw in the C1 vertebra was developed using 3-D printing. Eight real-size models of the high cervical spine and their respective screw guides were built using computed tomography (CT) scan images. The guidewires were inserted with the help of the printed guides and then the models were analyzed with the help of CT scan images. Results All of the guidewires in the present study obtained a safe placement in the models, avoiding the superior and inferior articular surfaces, the vertebral foramen, and the vertebral artery. Conclusion The present study demonstrated the efficiency of the guide, a reliable tool for aiding the insertion of guidewires for screws in lateral masses of the C1.

Resumo Objetivos A fixação de coluna cervical alta pode representar um desafio para os cirurgiões de coluna devido à anatomia complexa e aos riscos de lesão vascular e medular. Os recentes avanços com a tecnologia de impressão 3 D abriram um novo leque de opções para os cirurgiões. Métodos Desenvolveu-se umguia para a adaptação de parafusos demassa lateral em C1 comauxílio de impressão 3 D. Foram confeccionados oitomodelos em tamanho real de coluna cervical alta e seus respectivos guias com base em tomografias computadorizadas. Os fios-guia foram introduzidos com o auxílio dos guias; os modelos foram analisados com auxílio de tomografia computadorizada. Resultados Todos os fios-guia avaliados no estudo apresentaram um trajeto seguro nos modelos, respeitaram as superfícies articulares superiores e inferiores, o canal vertebral e a artéria vertebral. Conclusão O estudo demonstrou que o guia tem boa eficácia, é uma ferramenta confiável para auxiliar a adaptação de fios-guia para parafusos em massas laterais de C1.

Interaction of demographic factors with the results of the surgery for degenerative disease of the cervical spine: a retrospective evaluation / Interação dos dados demográficos com os resultados da cirurgia da doença degenerativa da coluna cervical: uma avaliação retrospectiva

ABSTRACT Objective: Degenerative disease of the cervical spine is a frequent source of intermittent neck pain, where the predominant symptom is axial neck pain. The indications for surgical treatment are reserved for the cases where the conservative treatment has not relieved the symptoms or the patient presents progressive neurological impairment. The objective of this study was to evaluate the prognostic factors involved in patients submitted to surgical treatment of the cervical spine, Methods: The study analyzed data from patients submitted to cervical spine surgery between July 2011 and November 2015 (n= 58). The evaluated data included smoking habits, hypertension, diabetes, overweight, surgical technique, and number of levels of fusion. The primary outcome was defined as pain and the secondary outcomes were quality of life and disability., Results: A statistically significant difference was found between baseline and the 12-month post-operative results regarding pain in favor of non-hypertensive patients (p= 0.009) and discectomy plus instrumentation (, p= 0.004). There was also significant difference between the results of neck disability in favor of non-hypertensive patients (p= 0.028) and patients with body mass index lower than 25, kg/m2 (p= 0.005). There was no significant interaction between any analyzed data and the quality of life score results. Conclusions: Non-hypertensive patients, those with body mass index lower than 25 kg/m2, and those submitted to discectomy combined with arthrodesis of the cervical spine are the most benefited by cervical degenerative disease surgery.

RESUMO Objetivo: A doença degenerativa da coluna cervical é uma fonte frequente de dor cervical intermitente, na qual os sintomas predominantes são dor axial cervical. As indicações para cirurgia são reservadas para os casos de falha do tratamento conservador ou com sintomas neurológicos progressivos. O objetivo deste estudo foi avaliar os fatores prognósticos dos pacientes submetidos ao tratamento cirúrgico da coluna cervical. Métodos: O estudo avaliou os pacientes submetidos à cirurgia da coluna cervical entre julho de 2011 e novembro de 2015 (n = 58). As variáveis de comparação avaliadas foram tabagismo, hipertensão, diabete, sobrepeso, técnica cirúrgica aplicada e número de níveis de artrodese. O desfecho primário foi definido como dor e os desfechos secundários foram qualidade de vida e disfunção. Resultados: Encontramos diferença estatisticamente significativa entre os escores de dor de base e aos 12 meses após a cirurgia, favorável aos pacientes sem hipertensão arterial sistêmica (p = 0,009) e aos submetidos à discectomia com instrumentação (p = 0,004). Também houve diferença estatisticamente significativa na avaliação da disfunção da coluna cervical: o resultado foi mais favorável para os pacientes sem diagnóstico prévio de hipertensão (p = 0,028) e para os pacientes com IMC menor do que 25 kg/m2(p = 0,005). Não se observou evidência de interação significativa entre os dados avaliados e os resultados do questionário de qualidade de vida. Conclusões: Os pacientes não hipertensos, com índice de massa corpórea menor do que 25 kg/cm2e submetidos à artrodese combinada à discectomia, são os mais beneficiados com o procedimento cirúrgico da doença degenerativa da coluna cervical.

Adjacent Segment Pathology after Anterior Cervical Fusion

Anterior cervical fusion has become a standard of care for numerous pathologic conditions of the cervical spine. However, subsequent development of clinically significant disc disease at levels adjacent to fused discs is a serious long-term complication of this procedure. As more patients live longer after surgery, it is foreseeable that adjacent segment pathology (ASP) will develop in increasing numbers of patients. Also, ASP has been studied more intensively with the recent popularity of motion preservation technologies like total disc arthroplasty. The true nature and scope of ASP remains poorly understood. The etiology of ASP is most likely multifactorial. Various factors including altered biomechanical stresses, surgical disruption of soft tissue and the natural history of cervical disc disease contribute to the development of ASP. General factors associated with disc degeneration including gender, age, smoking and sports may play a role in the development of ASP. Postoperative sagittal alignment and type of surgery are also considered potential causes of ASP. Therefore, a spine surgeon must be particularly careful to avoid unnecessary disruption of the musculoligamentous structures, reduced risk of direct injury to the disc during dissection and maintain a safe margin between the plate edge and adjacent vertebrae during anterior cervical fusion.

Experimental evaluation the influence of radiofrequency ablation nucleoplasty on sheep cervical spine stability / 中国医师杂志

Objective To evaluate the influence of the single and multiple intervertebral space radiofrequency ablation nucleoplasty on the sheep cervical spine stability.Methods Twenty healthy adult sheep were randomly divided into single intervertebral space operation group (A group )and multiple intervertebral space operation group ( B group ),each group was subdivided into postoperative 24 hours group ( A1,B1 group ) and post- operative 3 months group ( A2,B2 group),each group had five sheep.Radiofrequency ablation nucleoplasty on sheep C3/4 in the single intervertebral space operation group or C3/4,C4/5 in multiple intervertebral space operation group.Preoperative cervical vertebrae roentgenograms from all samples in neutral,lateral,hyperextension and hyperflexion positions were collected,and 5F pipe was used as the survey mark of ieonography.For the postoperative 24 hours group( A1,B1 group ),the roentgenograms were collected postoperatively 24 hours later,while for post- operative 3 months group (A2,B2 group),they were collected postoperatively 3 months later.The height of operative intervertebral space,horizontal and angular displacement of neighboring vertebral body were measured respectively.Results The roentgenograms showed no any obvious decrease in the height of intervertebral disc and no any increase in horizontal and angular displacement of neighboring vertebral body were observed in single intervertebral space operation group (A group) and multiple intervertebral space operation group (B group ).There was no significant difference between pre - operation and post - operation in them ( P ＞ 0.05 ).Conclusions The stability of the sheep cervical spine had not been affected by the single or multiple intervertebral space radiofrequency ablation nucleoplasty on the basis of X-ray results.The radiofrequency ablation nucleoplasty had no influences on the stability of sheep cervical vertebrae.

Target-controlled remtfentanil infusion combined with cervical plexus block for anterior cervical decompression surgery / 中华麻醉学杂志

Objective To evaluate the efficacy and safety of target-controlled remifentanil infusion combined with cervical plexus block for anterior cervical decompression surgery.Methods Twenty ASAⅠ or Ⅱpatients aged 30-64 yr undergoing anterior cervical decompression were studied.After a succegsful cervical plexus block,TCI of remifentanil was started at a target plasma concentration(CP)of 1.5 ng/ml 5 min before operation.The remifentanil CP was adjusted according to the patient's response to surgical stimulation and increased or decreased by 0.2 ng/ml each time until Ramsay sedation score reached 2-3 or verbal pain score(VPS)reached 0-1.TCI of remifentanil was discontinued 5 min before the end of surgery.MAP,HR,SpO2,BIS,Ramsay sedation score and VPS were monitored and recorded before cervical plexus block(To,baseline),at 10 min after cervical plexus block(T1),5 min(T2),30 min(T3)after skin incision,when the response to tracheal traction was significant during operation(T4)and at the end of operation(T5).The highest remifentanil Cp and the side effects such as respiratory depression,muscle rigidity,nausea/vomiting and pruritis that occurred were recorded.Remits MAP,SpO2 and BIS were not significantly changed during operation as compared to the baseline values at T0.HR was significantly increased at T2 as compared with the baseline.The Ramsay score reached 2-3 and the VPS reached 0-1 in the majority of patients in group R.No marked side effects were detected during TCI of remifentanil.The remifentanil CP ranged between 1.5-5 ng/ml and the mean CP during operation was(3.4±1.0)ng/ml.Conclusion TCI of remifentanil of low concentration combined with cervical plexus block can safely and effectively induce awake analgesia in patients undergoing anterior cervical decompression surgery.