腰椎椎弓根螺钉攻丝不足会导致攻丝螺距与螺钉螺距不同，从而降低螺钉拔出力。
Undertapping of Lumbar Pedicle Screws Can Result in Tapping With a Pitch That Differs From That of the Screw, Which Decreases Screw Pullout Force.
作者信息
Bohl Daniel D, Basques Bryce A, Golinvaux Nicholas S, Toy Jason O, Matheis Erika A, Bucklen Brandon S, Grauer Jonathan N
机构信息
*Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT †Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL ‡Department of Orthopaedic Surgery and Rehabilitation, Vanderbilt School of Medicine, Nashville, TN; and §Globus Medical Inc., Audubon, PA.
出版信息
Spine (Phila Pa 1976). 2015 Jun 15;40(12):E729-34. doi: 10.1097/BRS.0000000000000922.
STUDY DESIGN
Survey of spine surgeons and biomechanical comparison of screw pullout forces.
OBJECTIVE
To investigate what may be a suboptimal practice regularly occurring in spine surgery.
SUMMARY OF BACKGROUND DATA
In order for a tap to function in its intended manner, the pitch of the tap should be the same as the pitch of the screw. Undertapping has been shown to increase the pullout force of pedicle screws compared with line-to-line tapping. However, given the way current commercial lumbar pedicle screw systems are designed, undertapping may result in a tap being used that has a different pitch from that of the screw (incongruent pitch).
METHODS
A survey asked participants questions to estimate the proportion of cases each participant performed in the prior year using various hole preparation techniques. Participant responses were interpreted in the context of manufacturing specifications of specific instrumentation systems. Screw pullout forces were compared between undertapping with incongruent pitch and undertapping with congruent pitch using 0.16 g/cm polyurethane foam block and 6.5-mm screws.
RESULTS
Of the 3679 cases in which participants reported tapping, participants reported line-to-line tapping in 209 cases (5%), undertapping with incongruent pitch in 1156 cases (32%), and undertapping with congruent pitch in 2314 cases (63%). The mean pullout force for undertapping with incongruent pitch was 56 N (8%) less than the mean pullout force for undertapping with congruent pitch. This is equivalent to 13 lb.
CONCLUSION
This study estimates that for about 1 out of every 3 surgical cases with tapping of lumbar pedicle screws in the United States, hole preparation is being performed by undertapping with incongruent pitch. This study also shows that undertapping with incongruent pitch results in a decrease in pullout force by 8% compared with undertapping with congruent pitch. Steps should be taken to correct this suboptimal practice.
LEVEL OF EVIDENCE
研究设计
脊柱外科医生调查及螺钉拔出力的生物力学比较。
目的
调查脊柱手术中可能经常出现的次优操作。
背景数据总结
为使丝锥按预期方式发挥作用，丝锥的螺距应与螺钉的螺距相同。与逐线攻丝相比，欠攻丝已被证明可增加椎弓根螺钉的拔出力。然而，鉴于当前商用腰椎椎弓根螺钉系统的设计方式，欠攻丝可能导致使用的丝锥螺距与螺钉螺距不同（螺距不一致）。
方法
一项调查向参与者提问，以估计每位参与者在上一年使用各种钻孔准备技术的病例比例。参与者的回答是在特定器械系统制造规格的背景下进行解读的。使用0.16 g/cm聚氨酯泡沫块和6.5毫米螺钉，比较螺距不一致的欠攻丝和螺距一致的欠攻丝之间的螺钉拔出力。
结果
在参与者报告攻丝的3679例病例中，参与者报告逐线攻丝209例（5%），螺距不一致的欠攻丝1156例（32%），螺距一致的欠攻丝2314例（63%）。螺距不一致的欠攻丝的平均拔出力比螺距一致的欠攻丝的平均拔出力小56 N（8%）。这相当于13磅。
结论
本研究估计，在美国每3例腰椎椎弓根螺钉攻丝手术病例中，约有1例的钻孔准备是通过螺距不一致的欠攻丝进行的。本研究还表明，与螺距一致的欠攻丝相比，螺距不一致的欠攻丝导致拔出力降低8%。应采取措施纠正这种次优操作。
证据级别
3级。
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