A novel 3D-printed locking cage for anterior atlantoaxial fixation and fusion: case report and in vitro biomechanical evaluation

Abstract Background Treatment of atlantoaxial dislocation is aimed at reduction and stabilization of the atlantoaxial joint. 3D printing refers to a process where additive manufacturing is achieved under precise computer control. Literature on its utilization in anterior atlantoaxial fixation and fusion is rare. This study is the first report on a 3D-printed locking cage used in the anterior procedure for atlantoaxial dislocation. Methods A middle-aged male in his 40s presented with weakness and numbness of his extremities for 3 years and could only walk slowly with assistance. Imaging studies revealed severe anterior migration of C1, irreducible atlantoaxial dislocation, and severe cervical-medullary compression. A preoperative plan consisting of trans-oral soft tissue release and fixation using tailor-designed 3D-printed cages was devised. Following fluoroscopic confirmation of reduction of the atlantoaxial joints, two customized 3D-printed cages made of titanium alloy were inserted into the bilateral facet joints, which were then locked by six screws into the lateral masses of C1 and C2. The microstructure of the inserted cages was optimized for improved biomechanical stability and enhanced osseo-integration, without the need for bone grafting. In addition, a biomechanical test was performed on seven human cadaveric specimens comparing the novel implant with the conventional C1 lateral mass-C2 pedicle screw construct in three modes of motion (flexion-extension, lateral bending, axial rotation). Results Improvement of neurologic function in the patient was evident immediately after surgery. He was able to walk independently 1 month post-operatively. At the 12-month follow-up, coronal reconstruction of CT demonstrated properly-positioned 3D-printed cages, evidence of osseo-integration at the bone-implant interface, and no subsidence or displacement of the implant. Eighteen months out of surgery, the mJOA score improved to 15, and lateral X-ray confirmed reduction of atlanto-axial dislocation. Additionally, the new construct provided strong fixation comparable to that conferred by conventional constructs as there was no significant difference observed between the two groups in all three directions of motion. Conclusions The novel implant represents a new option in the treatment of irreducible atlantoaxial dislocation. It can provide strong anterior support for solid fixation and fusion with a low profile and a microstructure that obviates the need for bone grafting.

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Transoral intraarticular cage distraction and C-JAWS fixation for revision of basilar invagination with irreducible atlantoaxial dislocation

BMC Musculoskeletal Disorders ◽

10.1186/s12891-020-03792-3 ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Xiaobao Zou ◽

Binbin Wang ◽

Haozhi Yang ◽

Su Ge ◽

Bieping Ouyang ◽

...

Keyword(s):

Revision Surgery ◽

Odontoid Process ◽

Basilar Invagination ◽

Atlantoaxial Dislocation ◽

Atlantoaxial Instability ◽

Cervical Cord ◽

Atlantoaxial Joint ◽

Japanese Orthopedic Association ◽

Satisfactory Outcome ◽

Irreducible Atlantoaxial Dislocation

Abstract Background The revision surgery of basilar invagination (BI) with irreducible atlantoaxial dislocation (IAAD) after a previous occipitocervical fusion (OCF) is challenging. Transoral revision surgery has more advantages than a combined anterior and posterior approach in addressing this pathology. The C-JAWS is a cervical compressive staple that has been used in the lower cervical spine with many advantages. Up to now, there is no report on the application of C-JAWS in the atlantoaxial joint. We therefore present this report to investigate the clinical outcomes of transoral intraarticular cage distraction and C-JAWS fixation for revision of BI with IAAD. Methods From June 2011 to June 2015, 9 patients with BI and IAAD were revised by this technique after previous posterior OCF in our department. Plain cervical radiographs, computed tomographic scans and magnetic resonance imaging were obtained pre- and postoperatively to assess the degree of atlantoaxial dislocation and compression of the cervical cord. The Japanese Orthopedic Association (JOA) score was used to evaluate the neurological function. Results The revision surgeries were successfully performed in all patients. The average follow-up duration was 18.9 ± 7.3 months (range 9–30 months). The postoperative atlas-dens interval (ADI), cervicomedullary angle (CMA), distance between the top of the odontoid process and the Chamberlain line (CL) and JOA score were significantly improved in all patients (P < 0.05). Bony fusion was achieved after 3–9 months in all cases. No patients developed recurrent atlantoaxial instability. Conclusions Transoral revision surgery by intraarticular cage distraction and C-JAWS fixation could provide a satisfactory outcome for BI with IAAD after a previous unsuccessful posterior operation.

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Unilateral C-1 posterior arch screws and C-2 laminar screws combined with a 1-side C1–2 pedicle screw system as salvage fixation for atlantoaxial instability

Journal of Neurosurgery Spine ◽

10.3171/2015.4.spine14517 ◽

2016 ◽

Vol 24 (2) ◽

pp. 315-320 ◽

Cited By ~ 5

Author(s):

Jin Guo-Xin ◽

Wang Huan

Keyword(s):

Biomechanical Testing ◽

Pedicle Screws ◽

Atlantoaxial Instability ◽

Posterior Arch ◽

Lateral Bending ◽

Significant Difference ◽

Flexion Extension ◽

Intact Condition ◽

Atlantoaxial Fixation ◽

Group B

OBJECT Atlantoaxial instability often requires surgery, and the current methods for fixation pose some risk to vascular and neurological tissues. Thus, new effective and safer methods are needed for salvage operations. This study sought to assess unilateral C-1 posterior arch screws (PASs) and C-2 laminar screws (LSs) combined with 1-side C1–2 pedicle screws (PSs) for posterior C1–2 fixation using biomechanical testing with bilateral C1–2 PSs in a cadaveric model. METHODS Six fresh ligamentous human cervical spines were evaluated for their biomechanics. The cadaveric specimens were tested in their intact condition, stabilization after injury, and after injury at 1.5 Nm of pure moment in 6 directions. The 3 groups tested were bilateral C1–2 PSs (Group A); left side C1–2 PSs with an ipsilateral C-1 PAS + C-2 laminar screw (Group B); and left side C1–2 PSs with a contralateral C-1 PAS + C-2 LS (Group C). During the testing, angular motion was measured using a motion capture platform. Data were recorded, and statistical analyses were performed. RESULTS Biomechanical testing showed that there was no significant difference among the stabilities of these fixation systems in flexion-extension and rotation control. In left lateral bending, the bilateral C1–2 PS group decreased flexibility by 71.9% compared with the intact condition, the unilateral C1–2 PS and ipsilateral PAS+LS group decreased flexibility by 77.6%, and the unilateral C1–2 PS and contralateral PAS+LS group by 70.0%. Each method significantly decreased C1–2 movements in right lateral bending compared with the intact condition, and the bilateral C1–2 PS system was more stable than the C1–2 PS and contralateral PAS+LS system (p = 0.036). CONCLUSIONS A unilateral C-1 PAS + C-2 LS combined with 1-side C-1 PSs provided the same acute stability as the PS, and no statistically significant difference in acute stability was found between the 2 screw techniques. These methods may constitute an alternative method for posterior atlantoaxial fixation.

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Transoral Atlantoaxial Release and Posterior Reduction by Occipitocervical Plate Fixation for the Treatment of Basilar Invagination with Irreducible Atlantoaxial Dislocation

Journal of Neurological Surgery Part A Central European Neurosurgery ◽

10.1055/s-0036-1592199 ◽

2016 ◽

Vol 78 (04) ◽

pp. 313-320 ◽

Cited By ~ 8

Author(s):

Qingde Wang ◽

Kezheng Mao ◽

Chunli Wang ◽

Wei Mei

Keyword(s):

Plate Fixation ◽

Japanese Orthopaedic Association ◽

Basilar Invagination ◽

Atlantoaxial Dislocation ◽

Soft Tissue Release ◽

Posterior Fixation ◽

Improvement Rate ◽

Efficient Treatment ◽

Cord Injury ◽

Irreducible Atlantoaxial Dislocation

Background Prior studies have mainly assessed transoral odontoidectomy for basilar invagination with irreducible atlantoaxial dislocation. However, studies evaluating transoral release and posterior reduction with occipitocervical fixation in this setting are scarce. Methods From 2008 to 2013, 11 patients (6 men and 5 women; 23–67 years of age) with basilar invagination and irreducible atlantoaxial dislocation underwent surgery. They presented signs and symptoms of myelopathy or significant spinal cord injury, and were treated by transoral soft tissue release without odontoidectomy, under skull traction with heavy weight and by posterior reduction with occipitocervical plate fixation. Results Patients were followed up for 10 to 42 months (average: 25.4 months). All achieved bony fusion; radiologically complete reduction was achieved in 10 cases, and partial reduction in 1. All patients showed an improved postoperative neurologic condition, indicated by increased muscle strength and decreased or now absent pathologic symptoms. The average Japanese Orthopaedic Association preoperative score of 10.5 points increased to 15.5 points postoperatively. These findings indicated an improvement rate of 76.1%. The efficiency rate was 90.9%. Conclusions Anterior transoral atlantoaxial release without odontoidectomy and posterior fixation is an efficient treatment of basilar invagination with irreducible atlantoaxial dislocation.

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Atlantoaxial joint jamming as a treatment for atlantoaxial dislocation: a preliminary report

Journal of Neurosurgery Spine ◽

10.3171/spi-07/07/090 ◽

2007 ◽

Vol 7 (1) ◽

pp. 90-94 ◽

Cited By ~ 37

Author(s):

Atul Goel

Keyword(s):

Preliminary Report ◽

Atlantoaxial Dislocation ◽

Atlantoaxial Joint ◽

Facet Joints ◽

Alternative Treatment Strategy ◽

Atlantoaxial Fixation ◽

King Edward Memorial Hospital ◽

Atlantoaxial Stabilization ◽

The Mean

✓In this report the author describes an alternative technique of atlantoaxial fixation that involves blocking or “jamming” of movements of the atlantoaxial joint. The technique involves forcible impaction of spiked titanium metal spacers and bone grafts within the distracted atlantoaxial facet joints. Between January 2003 and January 2006, four patients underwent this method of fixation at the Department of Neurosurgery at King Edward Memorial Hospital in Mumbai, India. All four patients had posttraumatic mobile and reducible atlantoaxial dislocation. The mean follow-up period was 16 months (range 5–35 months). Successful atlantoaxial stabilization along with ultimate bone fusion was achieved in all patients and was documented on dynamic radiographs. There were no neurological, vascular, or infection-associated complications. The author concludes that the described method of atlantoaxial fixation provides an alternative treatment strategy. “Joint jamming” as a stand-alone method or in combination with other fixation methods may provide firm stabilization in cases of atlantoaxial dislocation.

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Left-right axial rotation within C1–2 after implant removal

Journal of Neurosurgery Spine ◽

10.3171/2013.8.spine1349 ◽

2013 ◽

Vol 19 (6) ◽

pp. 688-693 ◽

Cited By ~ 5

Author(s):

Tobias Pitzen ◽

Erbay Salman ◽

Gregor Ostrowski ◽

Thomas Welk ◽

Michael Ruf ◽

...

Keyword(s):

Surgical Treatment ◽

Neck Pain ◽

Range Of Motion ◽

Axial Rotation ◽

Mean Value ◽

Implant Removal ◽

Atlantoaxial Joint ◽

Advantages And Disadvantages ◽

Significant Difference ◽

Atlantoaxial Fixation

Object Surgical treatment of atlantoaxial injuries may be performed by a variety of surgical procedures, with each of these having its own specific advantages and disadvantages. To preserve the range of motion within the atlantoaxial joint after surgical treatment, posterior atlantoaxial screw fixation according to the method of Goel and Harms could be beneficial. This technique is not considered to fix the joint permanently if the screws are removed. However, this must not necessarily be true, especially if one notices that cervical joints have a tendency for rapid fusion after surgery. The objective of this study was to analyze left-right axial rotation following implant removal, with the following research questions addressed: 1) is there a relevant rotational left-right mobility in C1–2; 2) is there a difference in mobility depending on sex; 3) is there a correlation of mobility to age; 4) is there a correlation of mobility to the “implant-in-body time”; and 5) is neck pain improved by this method of surgical treatment? Methods This is a retrospective study in 10 patients who had received atlantoaxial fixation according to the Harms method following atlantoaxial injury. These patients had undergone implant removal after a mean time of 128 days, followed by functional atlantoaxial CT in left-right rotation. Statistical analysis was performed using the SPSS software package; significance was assumed for p < 0.05. Results The following findings are reported. 1) Left-right axial rotation within the atlantoaxial joint was measured to be 17° (mean value) following implant removal. 2) There was no significant difference between men (20°) and women (14.8°) (p = 0.595). 3) Left-right axial rotation negatively correlated to the age of the patient (r = −0.646, p = 0.043). 4) “Implant-in-body time” did not influence left-right axial rotation (r = 0.04, p = 0.907) if the implants are removed within 90–180 days after surgery. 5) Neck pain as assessed by the patients themselves on the visual analog scale was 7.9 ± 1.1 preoperatively and 3.6 ± 1.2 (mean ± SD) after implant removal (p = 0.002). Conclusions The authors conclude that removal of the implants 3–6 months after posterior atlantoaxial fixation according to the method of Goel and Harms is beneficial for obtaining some axial rotation within the atlantoaxial joint. The range of motion preserved depends on the age of the patient.

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Comparative Study for the Assay of Plant Derived Chemicals in Pharmaceutical Formulation Using Methods Dependent on Factorized Spectra

Journal of AOAC International ◽

10.1093/jaoacint/qsab027 ◽

2021 ◽

Author(s):

Nesma M Fahmy ◽

Adel M Michael

Keyword(s):

Pharmaceutical Formulations ◽

Pharmaceutical Formulation ◽

Ternary Mixtures ◽

Ratio Method ◽

The Novel ◽

Naturally Occurring ◽

Accuracy And Precision ◽

Validation Parameters ◽

Significant Difference

Abstract Background Modern built-in spectrophotometer software supporting mathematical processes provided a solution for increasing selectivity for multicomponent mixtures. Objective Simultaneous spectrophotometric determination of the three naturally occurring antioxidants—rutin(RUT), hesperidin(HES), and ascorbic acid(ASC)—in bulk forms and combined pharmaceutical formulation. Method This was achieved by factorized zero order method (FZM), factorized derivative method (FD1M), and factorized derivative ratio method (FDRM), coupled with spectrum subtraction(SS). Results Mathematical filtration techniques allowed each component to be obtained separately in either its zero, first, or derivative ratio form, allowing the resolution of spectra typical to the pure components present in Vitamin C Forte® tablets. The proposed methods were applied over a concentration range of 2–50, 2–30, and 10–100 µg/mL for RUT, HES, and ASC, respectively. Conclusions Recent methods for the analysis of binary mixtures, FZM and FD1M, were successfully applied for the analysis of ternary mixtures and compared to the novel FDRM. All were revealed to be specific and sensitive with successful application on pharmaceutical formulations. Validation parameters were evaluated in accordance with the International Conference on Harmonization guidelines. Statistical results were satisfactory, revealing no significant difference regarding accuracy and precision. Highlights Factorized methods enabled the resolution of spectra identical to those of pure drugs present in mixtures. Overlapped spectra of ternary mixtures could be resolved by spectrum subtraction coupled FDRM (SS-FDRM) or by successive application of FZM and FD1M.

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Regenerative Therapy Modality for Treatment of True Combined Endodontic-Periodontal Lesions: A Randomized Controlled Clinical Trial

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18126220 ◽

2021 ◽

Vol 18 (12) ◽

pp. 6220

Author(s):

Reham AlJasser ◽

Sundus Bukhary ◽

Mohammed AlSarhan ◽

Dalal Alotaibi ◽

Saleh AlOraini ◽

...

Keyword(s):

Bone Graft ◽

Bone Grafting ◽

Endodontic Treatment ◽

Control Group ◽

Controlled Clinical Trial ◽

Bony Defect ◽

Keratinized Tissue ◽

Group I ◽

Significant Difference ◽

Grafting Procedure

The aim of this in-vivo study was to evaluate/compare the clinical periodontal parameters in patients with true combined endo-perio lesions (EPL), treated with gutta-percha (GP) and mineral trioxide (MTA) as an obturation material alone and with addition of bone grafting in such lesions. 120 Saudi patients (mean age = 41yrs) diagnosed with true combined EPL participated in this study. Group I (control group, n = 30) was treated with conventional endodontic treatment using GP for obturation. Group II (n = 30) was treated with conventional endodontic treatment using MTA for obturation. Group III (n = 30) was treated with conventional endodontic treatment using GP for obturation + grafting procedure to fill the bony defect. Group IV (n = 30) was treated with conventional endodontic treatment using MTA for obturation + grafting procedure to fill the bony defect. Clinical parameters (Pocket depth (PD); Clinical attachment loss (CAL); keratinized tissue width (KTW); gingival phenotype (G.Ph.) and Cone Beam Computed Tomography Periapical Index (CBCTPAI)) were recorded and compared at baseline, 3, 6, 12 months’ interval. For the groups III and IV, CBCTPAI showed significant difference (p < 0.0001) with the other groups at 6 months and 1-year interval. The group with MTA + bone graft showed 76% and 90% patients with 0 score at 6 months and 1-year follow-up, respectively. Comparison of mean values of PD among study groups at 3 months, 6 months and 1 year showed significant difference at 3 months, whereas the mean PD values of subjects in GP + bone graft showed significantly higher PD values than other 3 groups (p = 0.025). Use of GP and MTA for root canal obturation along with periodontal therapy and bone augmentation helps in resolving complex endo-perio lesions. Bone grafting in addition to obturation with MTA was found to be the best treatment strategy in management of EPL cases and is recommended for clinicians who are treating EPL patients.

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Proximal Row Carpectomy with Total Scapoidectomy vs. Conventional Carpal Resection for ReMotion Total Wrist Arthroplasty

Journal of Clinical Medicine ◽

10.3390/jcm10091865 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1865

Author(s):

Stefan M. Froschauer ◽

Matthias Holzbauer ◽

Dietmar Hager ◽

Oskar Kwasny ◽

Dominik Duscher

Keyword(s):

Grip Strength ◽

Clinical Assessment ◽

Complication Rates ◽

Proximal Row Carpectomy ◽

Prosthesis Implantation ◽

Total Wrist Arthroplasty ◽

Significant Difference ◽

Flexion Extension ◽

Wrist Arthroplasty

High complication rates in total wrist arthroplasty (TWA) still lead to controversy in the medical literature, and novel methods for complication reduction are warranted. In the present retrospective cohort study, we compare the outcomes of the proximal row carpectomy (PRC) method including total scaphoidectomy (n = 22) to the manufacturer’s conventional carpal resection (CCR) technique, which retains the distal pole of the scaphoid (n = 25), for ReMotion prosthesis implantation in non-rheumatoid patients. Mean follow-up was 65.8 ± 19.8 and 80.0 ± 28.7 months, respectively. Pre- and postoperative clinical assessment included wrist flexion-extension and radial-ulnar deviation; Disability of Arm, Shoulder, and Hand scores; and pain via visual analogue scale. At final follow-up, grip strength and satisfaction were evaluated. All complications, re-operations, and revision surgeries were noted. Clinical complications were significantly lower in the PRC group (p = 0.010). Radial impaction was detected as the most frequent complication in the CCR group (n = 10), while no PRC patients suffered from this complication (p = 0.0008). Clinical assessment, grip strength measurements, and the log rank test evaluating the re-operation as well as revision function showed no significant difference. All functional parameters significantly improved compared to preoperative values in both cohorts. In conclusion, we strongly recommend PRC for ReMotion prosthesis implantation.

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Dimensional Accuracy of Dental Models for Three-Unit Prostheses Fabricated by Various 3D Printing Technologies

Materials ◽

10.3390/ma14061550 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1550

Author(s):

Soo-Yeon Yoo ◽

Seong-Kyun Kim ◽

Seong-Joo Heo ◽

Jai-Young Koak ◽

Joung-Gyu Kim

Keyword(s):

Surface Roughness ◽

Three Dimensional ◽

Dimensional Accuracy ◽

3D Analysis ◽

Digital Light Processing ◽

Test Models ◽

Reference File ◽

Significant Difference ◽

Jet Printing ◽

3D Printed

Previous studies on accuracy of three-dimensional (3D) printed model focused on full arch measurements at few points. The aim of this study was to examine the dimensional accuracy of 3D-printed models which were teeth-prepped for three-unit fixed prostheses, especially at margin and proximal contact areas. The prepped dental model was scanned with a desktop scanner. Using this reference file, test models were fabricated by digital light processing (DLP), Multi-Jet printing (MJP), and stereo-lithography apparatus (SLA) techniques. We calculated the accuracy (trueness and precision) of 3D-printed models on 3D planes, and deviations of each measured points at buccolingual and mesiodistal planes. We also analyzed the surface roughness of resin printed models. For overall 3D analysis, MJP showed significantly higher accuracy (trueness) than DLP and SLA techniques; however, there was not any statistically significant difference on precision. For deviations on margins of molar tooth and distance to proximal contact, MJP showed significantly accurate results; however, for a premolar tooth, there was no significant difference between the groups. 3D color maps of printed models showed contraction buccolingually, and surface roughness of the models fabricated by MJP technique was observed as the lowest. The accuracy of the 3D-printed resin models by DLP, MJP, and SLA techniques showed a clinically acceptable range to use as a working model for manufacturing dental prostheses

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