Objectives: 

Achieving calcar fixation is critical to minimize the failure of proximal humerus fractures repaired with proximal humeral locking plates (PHLPs). Many operative technique manuals reference the greater tuberosity (GT) for plate placement. The objective of this study was to examine the accuracy of calcar screw placement when PHLPs were placed based on distance from the GT.

Methods: 

Twenty cadaveric specimens were acquired representing a height distribution across the US population. Thirteen different PHLPs were applied. A drill bit was placed through the designated calcar screw hole and measured on radiographs, with the inferior 25% of the head representing an ideal placement.

Results: 

Three hundred fifty constructs were studied. In 28% of the specimens, the calcar screw was misplaced. In 20% of the specimens, it was too low, whereas in 8%, it was too high. The calcar screw missed low in 30% of patients shorter than 5 feet, 5.5 inches versus 8% of taller patients (P = 0.007). It missed high in 13% of taller patients versus 2% of shorter patients (P = 0.056). Calcar screws in variable-angle plates missed 0% of the time, whereas those in fixed-angle plates missed 36% of the time (P = 0.003).

Conclusions: 

Placement of PHLPs based on distance from the GT results in unacceptable position of the calcar screw 28% of the time and up to 36% in fixed-angle plates. This could be further compounded if the GT is malreduced. Current technique guide recommendations result in an unacceptably high rate of calcar screw malposition.

中文翻译：

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以大结节为基准置入肱骨近端钢板导致距骨螺钉错位率高

目标： 

实现骨距固定对于最大程度地减少使用近端肱骨锁定板 (PHLP) 修复的肱骨近端骨折的失败至关重要。许多手术技术手册都参考了大结节 (GT) 来放置钢板。本研究的目的是检查根据距 GT 的距离放置 PHLP 时骨距螺钉放置的准确性。

方法： 

采集了 20 个代表美国人口身高分布的尸体标本。应用了十三种不同的 PHLP。钻头穿过指定的骨距螺钉孔并在射线照片上进行测量，头部下方的 25% 代表理想位置。

结果： 

研究了三百五十个构造。在 28% 的样本中，骨距螺钉错位。在 20% 的样本中，它太低了，而在 8% 的样本中，它太高了。在 30% 的身高低于 5 英尺 5.5 英寸的患者中，距骨螺钉漏过低位，而在身高较高的患者中，该比例为 8% ( P = 0.007)。13% 的高个子患者与 2% 的矮个子患者漏掉了高值 ( P = 0.056)。可变角度板中的距骨螺钉有 0% 的时间漏掉，而固定角度板中的距骨螺钉有 36% 的时间漏掉 ( P = 0.003)。

结论： 

根据与 GT 的距离放置 PHLP 会导致 28% 的时间中距骨距螺钉位置不可接受，而在固定角度钢板中则高达 36%。如果 GT 被错误减少，这可能会进一步复杂化。目前的技术指南建议导致距骨螺钉错位率高得令人无法接受。