探讨徒手置入下颈椎椎弓根螺钉的准确性,不同置钉角度的置钉偏差及不同置钉偏差的风险.方法:38例脊髓型颈椎病或颈椎外伤的患者,行颈后路单开门椎管扩大成形术或后路切开复位内固定手术的同时,徒手置入C3-7颈椎椎弓根钉行内固定,对术后复查的CT片进行测量,比较手术前后患者的神经功能变化及相关症状,评价分析螺钉不同的内倾角对椎弓根内、外壁的穿出风险.结果:38例患者共徒手置入232枚下颈椎椎弓根螺钉,患者手术后无头晕、头痛等症状,4例患者出现一过性C5神经根麻痹,保守治疗痊愈,其余患者神经症状无加重,CT测量颈椎椎弓根螺钉的平均内倾角为(40.15±5.24)°,85.3％的螺钉完全位于椎弓根内,椎弓根的上、下、内、外四壁均完整未穿透.螺钉内倾角＜ 20°者,无穿出椎弓根内壁的情况发生,但有可能穿出椎弓根外壁;螺钉内倾角大于50°者,无螺钉穿出椎弓根外壁、穿出椎体侧前方或侵入推动脉孔的情况发生,但有可能穿出椎弓根内壁.结论:徒手置入下颈椎椎弓根螺钉,绝大多数情况下能达到安全有效地置钉,不易出现偏差,螺钉的内倾角介于30 ～ 50°时,更为安全有效.%Objective To assess the precision, deviation and the risk of pedicle screws insertion in the lower cervical spine with a manual Placement technique. Methods Pedicle screws for internal fixation were placed with a manual placement technique into the C3-7 cervical vertebrae of 38 patients who had cervical spondylotic myelopathy or acute cervical spinal injury. As part of this procedure, these patients received either posterior cervical open-door laminoplasty or open reduction and fixation through posterior approach. Post-operative CT scans of cervical spine were applied to measure the leaning inside angle of the pedicle screws and ascertain whether the screws were placed inside the pedicle or not, in order to assess the accuracy and safety of the manual placement method, and further learn the factors affecting the safety of the manual placement technique. Relative complications and changes in nerve function were compared between pre- and post operatively. Results A total of 232 pedicle screws were placed by manual placement into the lower cervical spines of 38 patients. 4 cases with temporary C5 nerve root palsy whilethe others nerve function did not deteriorate after the surgery, Based on post-operative CT scans, the average leaning inside angle was (40.15±5.24)°, and about 85.3% of screws were completely placed inside the pedicles. Those pedicle screws with an insertion angle under 20° were at risk for piercing the lateral cortex of the pedicles. Screws with angles greater than 50° posed no risk of piercing the lateral cortex or the transverse foramen but were capable of piercing the medial-cortex. Conclusions Manual insertion of pedicle screws into the lower cervical spine allows for a simple, fast surgery. In most cases, it can achieve safe and effective placement of pedicle screws, without much risk of deviating from the desired placement geometry. The safest and most effective placement strategy is a leaning inside angle between 30～ 50°. Moreover, this angle tended to decrease over time after the initial placement.
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