Kuklo Timothy R, Lehman Ronald A
Department of Orthopaedic Surgery and Rehabilitation, Walter Reed Army Medical Center, Washington, DC, USA.
Spine (Phila Pa 1976). 2003 Sep 15;28(18):2066-71. doi: 10.1097/01.BRS.0000084665.31967.02.
A biomechanical cadaver study to assess the effect of various tapping diameters on thoracic pedicle screw insertional torque.
Thoracic pedicle screws are now commonly used for deformity and nondeformity cases. The optimal insertion techniques, however, have not been determined.
To investigate the effect of various tapping techniques before insertion of thoracic pedicle screws in terms of maximal insertional torque (MIT) or screw pullout.
Thirty-four fresh cadaveric thoracic vertebrae were harvested and evaluated with dual-energy radiograph absorptiometry (DEXA) to assess bone mineral density (BMD). Twenty-three matched, fixed-head, 5.0-mm pedicle screws (group 1) were placed using the straight-forward (ST) trajectory (paralleling the endplate) at various thoracic levels after random side selection using either line-to-line tapping (5.0-mm tap) or 1-mm undertapping (4.0-mm tap) under direct and fluoroscopic visualization. After this, 11 matched 5.0-mm pedicle screws (group 2) were placed comparing undertapping by 0.5 mm (4.5-mm tap) with 1 mm undertapping (4.0-mm tap). MIT was recorded for each screw revolution with a digital torque wrench.
BMD averaged 0.732 g/cm2 (0.620-0.884 g/cm2) for group 1, and 614 g/cm2 (0.533-0.697 g/cm2) for group 2. In group 1, the average MIT was 0.153 +/- 0.009 (SE) Nm for line-to-line tapping and 0.295 +/- 0.021 (SE) Nm for 1-mm undertapping, a 93% increase in MIT (P < 0.0005). In group 2, the average MIT was 0.138 +/- 0.009 (SE) Nm for 0.5 mm undertapping and 0.202 +/- 0.018 (SE) Nm for undertapping by 1 mm, a 47% increase in MIT (P = 0.03). BMD correlated with undertapping by 1 mm in group 1 (P < 0.0005), but not with undertapping by 0.5 mm (P = 0.087), although there appeared to be a trend in osteoporotic specimens. There were no noted differences in MIT between thoracic regions/levels, despite small differences in thoracic pedicle widths (P = 0.193).
Undertapping the thoracic pedicle by 1-mm increases MIT by 47% (P = 0.03) when compared with undertapping by 0.5 mm, and by 93% (P < 0.0005) when compared with tapping line-to-line.
一项生物力学尸体研究，以评估不同攻丝直径对胸椎椎弓根螺钉插入扭矩的影响。
胸椎椎弓根螺钉目前常用于畸形和非畸形病例。然而，最佳的插入技术尚未确定。
研究在插入胸椎椎弓根螺钉之前，各种攻丝技术对最大插入扭矩（MIT）或螺钉拔出力的影响。
采集34个新鲜尸体胸椎，并用双能X线吸收法（DEXA）评估骨密度（BMD）。随机选择一侧后，在不同胸椎节段使用直线（ST）轨迹（与终板平行），通过逐线攻丝（5.0毫米丝锥）或1毫米欠攻丝（4.0毫米丝锥），在直视和透视下放置23枚匹配的、固定头的5.0毫米椎弓根螺钉（第1组）。此后，比较0.5毫米欠攻丝（4.5毫米丝锥）与1毫米欠攻丝（4.0毫米丝锥），放置11枚匹配的5.0毫米椎弓根螺钉（第2组）。用数字扭矩扳手记录每枚螺钉旋转时的MIT。
第1组BMD平均为0.732克/平方厘米（0.620 - 0.884克/平方厘米），第2组为0.614克/平方厘米（0.533 - 0.697克/平方厘米）。在第1组中，逐线攻丝的平均MIT为0.153±0.009（标准误）牛米，1毫米欠攻丝为0.295±0.021（标准误）牛米，MIT增加了93%（P < 0.0005）。在第2组中，0.5毫米欠攻丝的平均MIT为0.138±0.009（标准误）牛米，1毫米欠攻丝为0.202±0.018（标准误）牛米，MIT增加了47%（P = 0.03）。第1组中BMD与1毫米欠攻丝相关（P < 0.0005），但与0.5毫米欠攻丝无关（P = 0.087），尽管在骨质疏松标本中似乎有这种趋势。尽管胸椎椎弓根宽度存在微小差异（P = 0.193），但胸椎区域/节段之间的MIT没有显著差异。
与0.5毫米欠攻丝相比，胸椎椎弓根1毫米欠攻丝使MIT增加47%（P = 0.03），与逐线攻丝相比增加93%（P < 0.0005）。
