scholarly journals Posterior atlantoaxial fixation with new subfacetal axis screw trajectory avoiding vertebral artery with customized variable screw placement plate and screws to enhance biomechanics of fixation

2020 ◽  
Vol 3 (1) ◽  
pp. V10
Author(s):  
Sushil Patkar
Keyword(s):  
Vertebral Artery ◽  
Facet Joint ◽  
Articular Surface ◽  
Standard Of Care ◽  
Screw Placement ◽  
Atlantoaxial Instability ◽  
Technological Advances ◽  
Atlantoaxial Fixation ◽  
Screw Position ◽  
Developed World

Fixation for atlantoaxial dislocation is a challenging issue, and posterior C1 lateral mass and C2 pars–pedicle screw plate–rod construct is the standard of care for atlantoaxial instability. However, vertebral artery injury remains a potential complication. Recent literature has focused on intraoperative navigation, the O-arm, 3D printing, and recently use of robots for perfecting the trajectory and screw position to avoid disastrous injury to the vertebral artery and enhance the rigidity of fixation. These technological advances increase the costs of the surgery and are available only in select centers in the developed world.Review of the axis bone anatomy and study of the stress lines caused by weight transmission reveal that the bone below the articular surface of the superior facet is consistently dense as it lies along the line of weight transmission A new trajectory for the axis screw 3–5 mm below the midpoint of the facet joint and directed downward and medially avoids the course of the vertebral artery and holds the axis rigidly. Divergent screw constructs are biomechanically stronger. Variable screw placement (VSP) plates with long shaft screws permit manipulation of the vertebrae and realignment of the facets to the correct reduced position with fixation in the compression mode.The video can be found here: https://youtu.be/E1msiKjM-aA

scholarly journals Unstable odontoid fractures: technical appraisal of anterior extrapharyangeal open reduction internal fixation for irreducible unstable odontoid fractures. Patient series

2021 ◽  
Vol 2 (20) ◽  
Author(s):  
Sushil Patkar
Keyword(s):  
Open Reduction ◽  
Facet Joint ◽  
Open Reduction Internal Fixation ◽  
Atlantoaxial Instability ◽  
Rigid Fixation ◽  
Atlantoaxial Joint ◽  
Fracture Fragment ◽  
Odontoid Fractures ◽  
Atlantoaxial Fixation ◽  
Displaced Fracture

BACKGROUND Displaced odontoid fractures that are irreducible with traction and have cervicomedullary compression by the displaced distal fracture fragment or deformity caused by facetal malalignment require early realignment and stabilization. Realignment with ultimate solid fracture fusion and atlantoaxial joint fusion, in some situations, are the aims of surgery. Fifteen such patients were treated with direct anterior extrapharyngeal open reduction and realignment of displaced fracture fragments with realignment of the atlantoaxial facets, followed by a variable screw placement (VSP) plate in compression mode across the fracture or anterior atlantoaxial fixation (transarticular screws or atlantoaxial plate screw construct) or both. OBSERVATIONS Anatomical realignment with rigid fixation was achieved in all patients. Fracture fusion without implant failure was observed in 100% of the patients at 6 months, with 1 unrelated mortality. Minimum follow-up has been 6 months in 14 patients and a maximum of 3 years in 4 patients, with 1 unrelated mortality. LESSONS Most irreducible unstable odontoid fractures can be anatomically realigned by anterior extrapharyngeal approach by facet joint manipulation. Plate (VSP) and screws permit rigid fixation in compression mode with 100% fusion. Any associated atlantoaxial instability can be treated from the same exposure.

scholarly journals C1-C2 screw fixation in the patient with anomalous course of vertebral artery: Case report

2019 ◽  
Vol 76 (5) ◽  
pp. 555-558 ◽  
Author(s):  
Drazen Ivetic ◽  
Goran Pavlicevic ◽  
Branislav Antic
Keyword(s):  
Case Report ◽  
Vertebral Artery ◽  
Screw Fixation ◽  
Atlantoaxial Instability ◽  
Complicated Structure ◽  
Neurological Improvement ◽  
Degenerative Disorders ◽  
Translaminar Screw ◽  
Atlantoaxial Fixation ◽  
Alternative Fixation

Introduction. The atlantoaxial complex is a very complicated structure and open reduction of C1-C2 subluxation is very demanding. Atlantoaxial instability may result from the traumatic, inflammatory, neoplastic, congenital or degenerative disorders. Anatomy of the vertebral artery is essential for surgical approach and sometimes the placement of C2 pedicle screw is not possible. In these instances, the translaminar screw placement in C2 can provide an alternative fixation point in C2, without threatening injury to the vertebral artery. Case report. We presented 54- year-old patient with cervical myelopathy according to traumatic atlantoaxial subluxation. Computed tomography angiography showed a bilateral vertebral artery anomaly of ?high-riding? type. The patient was operated and the posterior C1-C2 screws fixation was used. Due to the vertebral artery anomaly C2 screws were translaminary inserted. Complete reduction of C1-C2 subluxation and excellent neurological improvement were achieved. Conclusion. Surgical treatment of C1-C2 subluxation is very challenging. Many techniques of atlantoaxial fixation have been developed. The use of C2 translaminar screw is an alternative method of fixation in the treatment of atlantoaxial instability, especially in cases with the vertebral artery anomaly.

Morphometric Anatomy of the Posterior Aspect of the Atlas and the Vertebral Artery Groove in Relation to Lateral Mass Screw Placement

2021 ◽  
Author(s):  
Selda Aksoy ◽  
Bulent Yalcin
Keyword(s):  
Vertebral Artery ◽  
Screw Placement ◽  
Atlantoaxial Instability ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Entry Zone ◽  
Mean Width ◽  
The Mean ◽  
The Right

Abstract Background Atlantoaxial instability is an important disorder that causes serious symptoms such as difficulties in walking, limited neck mobility, sensory deficits, etc. Atlantal lateral mass screw fixation is a surgical technique that has gained important recognition and popularity. Because accurate drilling area for screw placement is of utmost importance for a successful surgery, we aimed to investigate morphometry of especially the posterior part of C1. Methods One hundred and fifty-eight human adult C1 dried vertebrae were obtained. Measurements were performed directly on dry atlas vertebrae, and all parameters were measured by using a digital caliper accurate to 0.01 mm for linear measurements. Results The mean distance between the tip of the posterior arch and the medial inner edge of the groove was found to be 10.59 ± 2.26 and 10.49 ± 2.20 mm on the right and left, respectively. The mean distance between the tip of the posterior arch and the anterolateral outer edge of the groove was 21.27 ± 2.28 mm (right: 20.96 ± 2.22 mm; left: 21.32 ± 2.27 mm). The mean height of the screw entry zone on the right and left sides, respectively, were 3.86 ± 0.81 and 3.84 ± 0.77 mm. The mean width of the screw entry zone on both sides was 13.15 ± 1.17 and 13.25 ± 1.3 mm. Conclusion Our result provided the literature with a detailed database for the morphometry of C1, especially in relation to the vertebral artery groove. We believe that the data in the present study can help surgeons to adopt a more accurate approach in terms of accurate lateral mass screw placement in atlantoaxial instability.

C1-2 Pedicle Screw Fixation for Ponticulus Posticus and Duplication of Vertebral Artery: 2-Dimensional Operative Video

2020 ◽  
Author(s):  
Yoon Gyo Jung ◽  
Byung-Jou Lee ◽  
Wonhyoung Park ◽  
Jin Hoon Park
Keyword(s):  
Computed Tomography ◽  
Vertebral Artery ◽  
Pedicle Screw ◽  
Facet Joint ◽  
Pedicle Screw Fixation ◽  
Screw Placement ◽  
Posterior Arch ◽  
Pedicle Screw Placement ◽  
Ponticulus Posticus ◽  
Patient Consent

Abstract We previously introduced C1 pedicle screw placement to treat C1-2 pathology in a patient with normal vertebral artery anatomy.1 However, we should prepare to meet various anatomic variations. Ponticulus posticus is a bony prominence arising from the posterior arch or the superior articulating process of the atlas that completely or partially encircles the vertebral artery.2 We herein report a 79-yr-old female who presented with myelopathy and was diagnosed with compressive myelopathy at the C1 level in magnetic resonance imaging. A computed tomography showed ponticulus posticus (complete type to the right side) with duplication of vertebral artery.  She underwent surgical treatment of C1-2 pedicle screw placement and reduction of C1 vertebra under a microscopic view. After C1 laminectomy, both-side vertebral arteries were dissected with a microscissor. The mobilization of upper divisions of vertebral artery was identified to secure the entry point and pedicle to insert a C1 pedicle screw. After complete protection of the upper and lower divisions of vertebral artery and identification of pedicle, a C1 pedicle screw was inserted by a freehand technique. We inserted autologous bone chips in the distracted C1-2 facet joint for facet joint fusion, and the C1 vertebra was pulled out by a rod reducer.  After surgery, the patient's symptoms disappeared, and no vertebral artery injury was identified in postoperative 3-dimensional computed tomography angiography.  Patient consent was obtained prior to performing the procedure.

Use of a titanium mesh cage for posterior atlantoaxial arthrodesis

2002 ◽  
Vol 96 (1) ◽  
pp. 127-130 ◽  
Author(s):  
Morio Matsumoto ◽  
Kazuhiro Chiba ◽  
Takashi Tsuji ◽  
Hirofumi Maruiwa ◽  
Yoshiaki Toyama ◽  
...  
Keyword(s):  
Donor Site ◽  
Atlantoaxial Instability ◽  
Os Odontoideum ◽  
Posterior Arch ◽  
Rigid Fixation ◽  
Titanium Mesh ◽  
Content Type ◽  
Atlantoaxial Fixation ◽  
Mesh Cage ◽  
Atlantoaxial Arthrodesis

✓ The authors placed titanium mesh cages to achieve posterior atlantoaxial fixation in five patients with atlantoaxial instability caused by rheumatoid arthritis or os odontoideum. A mesh cage packed with autologous cancellous bone was placed between the C-1 posterior arch and the C-2 lamina and was tightly connected with titanium wires. Combined with the use of transarticular screws, this procedure provided very rigid fixation. Solid fusion was achieved in all patients without major complications. The advantages of this method include more stable fixation, better control of the atlantoaxial fixation angle, and reduced donor-site morbidity compared with a conventional atlantoaxial arthrodesis in which an autologous iliac crest graft is used.

scholarly journals Tuber-to-Anterior Process Angle (TAPA): A Cadaveric Study and Surgical Technique for Placing Axial Calcaneal Screws

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0041
Author(s):  
Kristen L. Stupay ◽  
Jorge Briceno ◽  
Brian Velasco ◽  
John Y. Kwon
Keyword(s):  
Surgical Technique ◽  
Guide Wire ◽  
Articular Surface ◽  
Plate Fixation ◽  
Operative Management ◽  
Screw Placement ◽  
Anterior Process ◽  
Starting Point ◽  
K Wires ◽  
Average Angle

Category: Ankle, Hindfoot Introduction/Purpose: Operative management of displaced intra-articular calcaneus fractures frequently involves placement of P: A screws in order to maintain calcaneal length and axial alignment. While plate fixation may still be more commonly utilized, screw-only fixation for the treatment of these fractures has been demonstrated by several authors to be safe and effective. Directing fixation from the tuber into the anterior process can be challenging. Understanding the calcaneal long-axis as it relates to the long-axis of the foot, a measurement we call the Tuber-to-Anterior Process Angle (TAPA), can facilitate the ease and accuracy of guide-wire and cannulated screw placement. The goals of this study are to define the TAPA, and to report a surgical technique which uses this angle to facilitate axial screw placement. Methods: Eight cadaver feet were utilized. A longitudinal pin was placed from the center of the posterior calcaneal tuber to the 2nd metatarsal heads. Next, the calcaneocuboid joint was exposed, and a wedge of cuboid was removed. A calcaneal pin was then placed, exiting at the center of the anterior process. The tips of two small K-wires were impacted into the medial and lateral-most aspects of the articular surface. A true axial view of each specimen was obtained. On these images, a digital line was drawn from the posterior tuber starting point and the central calcaneal pin, representing the calcaneal long-axis. The angle subtended by this line and the long-axis of the foot represents the TAPA. Digital lines were drawn between the posterior tuber starting point and the medial and lateral K-wires, and the range between their subtending angles represents the axial plane tolerance for screw placement within the anterior process. Results: The average TAPA measured 10.9 ± 1.3 degrees (range: 8.4-13.0). The average angle, as measured to the medial extent of the anterior calcaneus, measured 2.8 ± 1.3 degrees (range: 0.4-4.3). The average angle, as measured to the lateral extent of the anterior calcaneus, measured 19.0 ± 2.7 degrees (range: 15.7-22.7). Conclusion: Knowledge of the Tuber-to-Anterior Process Angle (TAPA), found to be 10.9 degrees (± 1.8 degrees) laterally deviated from the long-axis of the foot, simplifies placement of posterior-to-anterior screws in the calcaneus. Understanding this relationship reduces reliance on intraoperative axial fluoroscopy and increases operative efficiency. Furthermore, this knowledge can be applied during other procedures in which axial screw placement is performed, such as with corrective calcaneal osteotomy.

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