| Optimal Trajectory for the Occipital Condylar Screw. | |
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MedLine Citation:
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PMID: 21544012 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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ABSTRACT: Study Design. Evaluation by simulation of screw insertion using fine cut CT scans and screw trajectory software.Objective. To evaluate the feasibility and optimal trajectory of the occipital condylar screw.Summary of Background Data. To the best of our knowledge, no large series examining the feasibility and optimal trajectory of occipital condylar screws have been published.Methods. We simulated unicortical placement of a 4 × 18 mm screw placement using 1 mm-sliced CT scans and three-dimensional screw trajectory software in 314 occipital condyles of 157 patients. With the screw tip directed toward a point just below the tip of the basion on lateral fluoroscopy, three entry points were compared in view of success rate of screw placement; safe range of medial angulation in an axial plane; and the maximum screw length.Results. The lateral entry point had the highest success rate of screw placement (93.0%), mean safe range of the medial angulation (10.9°), and maximum screw length (20.7 mm), followed by the middle (92.0%, 10.8°, and 20.6 mm, respectively) and medial (74.2%, 7.7°, and 19.7 mm respectively) entry points. While the lateral and the middle entry points did not have statistically significant difference in the 3 parameters, they were significantly better than the medial point. All three entry points had highly variable ranges of safe medial angulation, making it difficult to provide a single recommended value.Conclusion. Screw placement is feasible in up to 93% of the occipital condyles. The lateral and the middle entry points are significantly better than the medial entry point. Selection between the middle and the lateral entry points should be individualized taking into account local anatomic variation. Since the medial angulation of these screws is highly variable, preoperative three-dimensional CT evaluation and possibly even intraoperative navigation may be required. |
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Authors:
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Joon Oh Lee; Jacob M Buchowski; Kyoung Min Lee; Kun-Woo Park; Bong-Soon Chang; Choon-Ki Lee; K Daniel Riew; Jin S Yeom |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-3 |
Journal Detail:
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Title: Spine Volume: - ISSN: 1528-1159 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-5-5 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7610646 Medline TA: Spine (Phila Pa 1976) Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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*Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Hospital, Seoul, Korea †Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, Missouri, USA ‡Spine Center and Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Sungnam, Korea. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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