Donald Simon M, Niu Rui, Jones Christopher W, Smith Belinda J, Clarke Elizabeth C, Lawson Richard D
Department of Hand Surgery and Peripheral Nerve Surgery, Royal North Shore Hospital, University of Sydney, Sydney, Australia.
Murray Maxwell Biomechanics Laboratory, Kolling Institute, Sydney Medical School, University of Sydney, Sydney, Australia.
J Hand Surg Am. 2018 Feb;43(2):139-145. doi: 10.1016/j.jhsa.2017.10.002. Epub 2017 Nov 11.
This study investigates the loss of compression when 3 commonly used headless compression screws are backed out (reversed), and assesses the ability to re-establish compression with screws of greater diameter.
Two investigators tested 3 screw designs (Acutrak 2, Synthes HCS, Medartis SpeedTip CCS) in 2 diameters and lengths. Each design had 10 test cycles in a polyurethane foam bone model with compression recorded using a washer load cell. A 28-mm screw of the narrower diameter was inserted until 2 mm recessed and then reversed 30°, 60°, 90°, 180°, 270°, 360°, and 720°. After this the screw was removed completely and a 24-mm screw of greater diameter inserted until recessed 2 mm with the compressive force again recorded.
All screws showed an immediate, statistically significant loss of compression at 30° of reversing. The Acutrak 2 Micro screw demonstrated not only the greatest mean compressive force, but also the fastest compressive loss. Insertion of the shorter screw of greater diameter was associated with re-establishment of compression to levels comparable with the original screw.
This study reaffirms the importance of establishing the correct screw length before insertion due to the immediate loss of compression with reversal of these devices.
If a headless compression screw penetrates the far joint surface, the screw should be completely removed and replaced with a shorter screw of greater diameter.
本研究调查3种常用无头加压螺钉退出（反转）时的加压损失情况，并评估使用更大直径螺钉重新建立加压的能力。
两名研究者测试了2种直径和长度的3种螺钉设计（Acutrak 2、Synthes HCS、Medartis SpeedTip CCS）。每种设计在聚氨酯泡沫骨模型中进行10个测试周期，使用垫圈式称重传感器记录加压情况。插入较窄直径的28毫米螺钉，使其凹入2毫米，然后分别反转30°、60°、90°、180°、270°、360°和720°。之后将螺钉完全取出，插入更大直径的24毫米螺钉，使其凹入2毫米，再次记录压缩力。
所有螺钉在反转30°时均立即出现统计学上显著的加压损失。Acutrak 2微型螺钉不仅显示出最大的平均压缩力，而且加压损失最快。插入较短但直径更大的螺钉可使加压重新建立至与原始螺钉相当的水平。
本研究再次证实了在插入前确定正确螺钉长度的重要性，因为这些装置反转会立即导致加压损失。
如果无头加压螺钉穿透远侧关节面，应将螺钉完全取出，并用较短但直径更大的螺钉替换。
