Ballock R T, Lee T Q, Triggs K J, Woo S L, Garfin S R
Division of Orthopaedics and Rehabilitation, University of California, San Diego.
Neurosurgery. 1990 Feb;26(2):238-41. doi: 10.1097/00006123-199002000-00009.
Optimal insertion of halo fixation pins to maximize the rigidity of the interface between the halo pins and the outer table of the skull is important in reducing the incidence of pin loosening. An in vitro biomechanical study was performed using cadaver skulls to investigate the effects of pin location on the rigidity of this pin-bone interface. Halo pins were inserted at nine positions within a recommended "safe zone" for pin insertion. It was found that the rigidity of the pin-bone interface progressively decreased as pins were inserted more superiorly on the calvaria. The rigidity of the interface did not change significantly when the location of the pins was varied in the horizontal axis. This reduction in interface rigidity associated with inserting pins more superiorly on the skull may be related to an increase in the angle of insertion of the pins with respect to the surface of the calvaria. Based on this study, a change in the technique of halo pin insertion is recommended. Pins should be placed as inferiorly as possible, close to the supraorbital ridge, to achieve the most perpendicular angle of insertion and thus the most rigid fixation. The improved rigidity obtained with perpendicular pin insertion may minimize the rate of pin loosening and other complications associated with use of the halo orthosis.
优化头环固定针的插入，以最大限度地提高头环针与颅骨外板之间界面的刚性，对于降低针松动的发生率至关重要。使用尸体颅骨进行了一项体外生物力学研究，以调查针位置对该针-骨界面刚性的影响。在推荐的针插入“安全区”内的九个位置插入头环针。结果发现，随着针在颅盖上插入位置越来越靠上，针-骨界面的刚性逐渐降低。当针在水平轴上的位置改变时，界面的刚性没有显著变化。与在颅骨上更靠上插入针相关的界面刚性降低可能与针相对于颅盖表面的插入角度增加有关。基于这项研究，建议改变头环针的插入技术。针应尽可能靠下放置，靠近眶上嵴，以实现最垂直的插入角度，从而获得最牢固的固定。垂直插入针所获得的更高刚性可能会使针松动率以及与使用头环矫形器相关的其他并发症降至最低。
