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Abstract
STUDY DESIGN In vitro biomechanical study of flexibility with finite-element simulation to estimate screw stresses. OBJECTIVE To compare cervical spinal stability after a standard plated 3-level corpectomy with stability after a plated 3-level "skip" corpectomy where the middle vertebra is left intact (ie, two 1-level corpectomies), and to quantify pullout forces acting on the screws during various loading modes. SUMMARY OF BACKGROUND DATA Clinically, 3-level cervical plated corpectomy has a high rate of failure, partially because only 4 contact points affix the plate to the upper and lower intact vertebrae. Leaving the intermediate vertebral body intact for additional fixation points may overcome this problem while still allowing dural sac decompression. METHODS Quasistatic nonconstraining torque (maximum 1 N m) induced flexion, extension, lateral bending, and axial rotation while angular motion was recorded stereophotogrammetrically. Specimens were tested intact and after corpectomy with standard plated and strut-grafted 3-level corpectomy (7 specimens) or "skip" corpectomy (7 specimens). Screw stresses were quantified using a validated finite-element model of C3-C7 mimicking experimentally tested groups. Skip corpectomy with C5 screws omitted was also simulated. RESULTS Plated skip corpectomy tended to be more stable than plated standard corpectomy, but the difference was not significant. Compared with standard plated corpectomy, plated skip corpectomy reduced peak screw pullout force during axial rotation (mode of loading of highest peak force) by 15% (4-screw attachment) and 19% (6-screw attachment). CONCLUSIONS Skip corpectomy is a good alternative to standard 3-level corpectomy to improve stability, especially during lateral bending. Under pure moment loading, the screws of a cervical multilevel plate experience the highest pullout forces during axial rotation. Thus, limiting this movement in patients undergoing plated multilevel corpectomy may be reasonable, especially until solid fusion is achieved.
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Yoshii T, Hirai T, Yamada T, Inose H, Kato T, Sakai K, Enomoto M, Kawabata S, Arai Y, Okawa A. Intraoperative evaluation using mobile computed tomography in anterior cervical decompression with floating method for massive ossification of the posterior longitudinal ligament. J Orthop Surg Res 2017; 12:12. [PMID: 28103899 PMCID: PMC5244593 DOI: 10.1186/s13018-017-0515-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 01/11/2017] [Indexed: 11/10/2022] Open
Abstract
Background An anterior decompression and fusion (ADF) with the floating method is an effective procedure for treating ossification of the posterior longitudinal ligament (OPLL), allowing a direct decompressive effect on the spinal cord. However, the procedure is skill-intensive, particularly in cases of OPLL with a high canal-occupying ratio. In such cases, there are potential risks for insufficient decompression due to the incomplete floating of the OPLL. Here, we introduce an anterior decompression procedure for massive OPLL, using an intraoperative computed tomography (CT) with a mobile scanner gantry for the intraoperative evaluation of the decompression. We further evaluated the outcomes of ADF using mobile CT in comparison with a historical control of ADF without intraoperative CT evaluation. Methods Fifty OPLL patients who underwent ADF with the floating method were evaluated in this study: 25 patients with intraoperative CT (CT group) and 25 patients without CT (non-CT group). In the CT group, intraoperative CT scanning was performed before freeing the ossification from the surrounding bone tissues. The reconstructed images were reviewed to evaluate the extent of bone decompression and thinning of the OPLL. After review of the images, further thinning of the OPLL or removal of surrounding bone was performed as deemed necessary, to complete the floating of the OPLL. Results Patients’ background was similar between the CT and non-CT group. Operating time tended to be shorter for the CT group. On the postoperative CT, incomplete OPLL floating due to “impingement” between the OPLL and the medial aspect of the pedicle or uncovertebral joint was observed for four patients (16.0%) in the non-CT group, whereas insufficient decompression was not observed in the CT group. Conclusions Intraoperative CT imaging was effective to avoid insufficient decompression following ADF with the floating method for massive OPLL. We also consider that the intraoperative three-dimensional imaging is helpful for providing informative feedback to surgeons to improve performance in skill-intensive surgeries such as ADF with the floating method.
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Affiliation(s)
- Toshitaka Yoshii
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan. .,Section of Regenerative Therapeutics for Spine and Spinal Cord, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan. .,Tokyo Medical and Dental University Spine Group, Tokyo, Japan.
| | - Takashi Hirai
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Section of Regenerative Therapeutics for Spine and Spinal Cord, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Tsuyoshi Yamada
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Section of Regenerative Therapeutics for Spine and Spinal Cord, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Hiroyuki Inose
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Tsuyoshi Kato
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Kenichiro Sakai
- Saiseikai Kawaguchi General Hospital, Kawaguchi, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Mitsuhiro Enomoto
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Section of Regenerative Therapeutics for Spine and Spinal Cord, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Shigenori Kawabata
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Yoshiyasu Arai
- Saiseikai Kawaguchi General Hospital, Kawaguchi, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
| | - Atsushi Okawa
- Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Section of Regenerative Therapeutics for Spine and Spinal Cord, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.,Tokyo Medical and Dental University Spine Group, Tokyo, Japan
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Kim SH, Lee JH, Kim JH, Chun KS, Doh JW, Chang JC. Anatomical morphometric study of the cervical uncinate process and surrounding structures. J Korean Neurosurg Soc 2012; 52:300-5. [PMID: 23133716 PMCID: PMC3488636 DOI: 10.3340/jkns.2012.52.4.300] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 08/10/2012] [Accepted: 10/04/2012] [Indexed: 11/28/2022] Open
Abstract
Objective The purpose of this study is to elucidate the anatomic relationships between the uncinate process and surrounding neurovascular structures to prevent possible complications in anterior cervical surgery. Methods Twenty-eight formalin-fixed cervical spines were removed from adult cadavers and were studied. The authors investigated the morphometric relationships between the uncinate process, vertebral artery and adjacent nerve roots. Results The height of the uncinate process was 5.6-7.5 mm and the width was 5.8-8.0 mm. The angle between the posterior tip of the uncinate process and vertebral artery was 32.2-42.4°. The distance from the upper tip of the uncinate process to the vertebral body immediately above was 2.1-3.3 mm, and this distance was narrowest at the fifth cervical vertebrae. The distance from the posterior tip of the uncinate process to the nerve root was 1.3-2.0 mm. The distance from the uncinate process to the vertebral artery was measured at three different points of the uncinate process : upper-posterior tip, lateral wall and the most antero-medial point of the uncinate process, and the distances were 3.6-6.1 mm, 1.7-2.8 mm, and 4.2-5.7 mm, respectively. The distance from the uncinate process tip to the vertebral artery and the angle between the uncinate process tip and vertebral artery were significantly different between the right and left side. Conclusion These data provide guidelines for anterior cervical surgery, and will aid in reducing neurovascular injury during anterior cervical surgery, especially in anterior microforaminotomy.
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Affiliation(s)
- Sung-Ho Kim
- Department of Neurosurgery, Soonchunhyang University Gumi Hospital, Gumi, Korea
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