Institute of Engineering and Computational Mechanics, University of Stuttgart, Stuttgart, Germany.
Otol Neurotol. 2012 Aug;33(6):1077-84. doi: 10.1097/MAO.0b013e318259b34b.
The forces that cause rupture of the incudomalleolar joint during the fixation of stapedial prostheses can be determined by means of load-deflection measurements at the long process of the incus. As in other tissues, 3 ranges of forces can be defined: micro rupture, rupture, and short-term maximum.
A crucial step in stapes surgery is the attachment of the stapedial prosthesis to the long process of the incus. It is unknown which forces occur during the crimping process that increase the risk of damage to the incudomalleolar joint or incus luxation. The goal of this study was to assess the admissible range of forces at the long process of the incus that would be tolerable before damaging the structures and to compare them with the forces occurring during surgery.
Load-deflection curves in the lateral-medial and anterior-posterior direction were measured in 9 freshly frozen or fresh temporal bones. The force was measured with a load cell, and displacement was taken from the encoder information of the electrically driven translation stage on which the load cell was mounted. The long process of the incus was coupled to the load cell via a customized needle. We also monitored with video recordings for visual confirmation of findings.
The rupture force at which the middle ear was found to be severely injured was 894 (724-1018) mN in the anterior-posterior direction and 695 (574-771) mN in the lateral-medial direction. Micro-ruptures occurred at forces around 568 (469-686) mN in the anterior-posterior direction and in the lateral-medial direction at 406 (254-514) mN. Short-term maximum forces of 1,321 (1,051-1,533) mN were measured in the anterior-posterior direction and 939 (726-1,132) mN in the lateral-medial direction.
Rupture forces of the incudomalleolar joint could be defined with high accuracy. These results were used to calculate risks of incus luxation or subluxation during stapes surgery. Compared with the use of clip and SMA prostheses, the risk of damage from a crimping procedure is significantly higher.
通过对砧骨长突进行负载-挠度测量，可以确定在固定镫骨假体时导致砧镫关节破裂的力。与其他组织一样，可定义 3 个力范围：微破裂、破裂和短期最大力。
镫骨手术的一个关键步骤是将镫骨假体连接到砧骨长突。在镫骨手术中，在增加砧镫关节或砧骨脱位风险的镦粗过程中会产生哪些力尚不清楚。本研究的目的是评估在不损坏结构的情况下，砧骨长突可承受的允许力范围，并将其与手术中发生的力进行比较。
在 9 个新鲜冷冻或新鲜颞骨中测量侧向-内侧和前-后方向的负载-挠度曲线。力通过负载细胞测量，位移通过安装负载细胞的电动平移台的编码器信息获取。通过定制的针将砧骨长突与负载细胞耦合。我们还通过视频记录进行监测，以确认发现的结果。
在前-后方向，中耳严重受伤的破裂力为 894（724-1018）mN，在侧向-内侧方向为 695（574-771）mN。在前-后方向，微破裂发生在约 568（469-686）mN 的力下，在侧向-内侧方向发生在 406（254-514）mN 的力下。在前-后方向测量到的短期最大力为 1321（1051-1533）mN，在侧向-内侧方向测量到的短期最大力为 939（726-1132）mN。
可以准确地定义砧镫关节的破裂力。这些结果用于计算镫骨手术期间砧骨脱位或半脱位的风险。与使用夹和 SMA 假体相比，镦粗过程造成损伤的风险明显更高。
