Adjustable Posterior Fixation Suture Technique in Adjustable Superior Rectus Transposition

<b>Background</b>: Recently, the superior rectus transposition has been widely adopted for the treatment of complete abducens palsy and Duane syndrome. This procedure is useful in that there is a decreased risk of anterior segment ischemia compared to complete vertical rectus transposition, possibly decreased incidence of postoperative-induced vertical deviations than complete vertical rectus transposition, and improvement in abduction compared to simple medial rectus recession. One difficulty with this procedure is the lack of adjustability in most patients. Our group has adopted a new technique for an adjustable posterior fixation myopexy suture for use with patients under topical anesthesia. <b>Methods</b>: The superior rectus muscle is temporally transposed to the insertion of the lateral rectus muscle. The corner of the superior rectus muscle that is placed adjacent to the lateral rectus muscle is placed on an adjustable suture. Then, a posterior fixation myopexy suture consisting of a single-armed 6-0 vicryl suture is secured between the superior and lateral rectus muscles, approximately 10 mm from the lateral rectus insertion to drag the superior rectus muscle temporally. This suture is also placed on an adjustable suture. The patient is then positioned sitting up, fixing at a target at approximately 10 feet away from the patient’s head. Cover testing is utilized to determine whether any vertical deviation has been induced. If there is a vertical deviation, the posterior fixation suture may be loosened. <b>Results</b>: We find that this technique to be useful if an induced vertical deviation or an overcorrection occur, and is thought to be due to the reported possible complication of restriction induced by the posterior fixation suture and the transposed rectus muscle. <b>Conclusion</b>: Our technique for performing superior rectus transposition with an adjustable posterior fixation myopexy suture may be useful to surgeons who wish to have an adjustable option as a way to decrease the risk of postoperative complications such as induced vertical deviations and overcorrections.

<b>背景</b>: 近期，上直肌（superior rectus muscle）移位术已被广泛应用于完全性外展神经麻痹（abducens palsy）与Duane综合征（Duane syndrome）的临床治疗。相较于完全性垂直直肌移位术，该术式具有多重临床优势：眼前段缺血（anterior segment ischemia）风险更低，术后诱发垂直斜视的发生率可能更低，且相较单纯内直肌后退术（medial rectus recession），患者的外展功能可获得改善。但该术式存在一项固有局限：多数患者无法实现术中调整。本研究团队开发了一项新技术，可在表面麻醉（topical anesthesia）下为患者实施可调式后固定肌缝线固定术（posterior fixation myopexy suture）。
<b>方法</b>: 将上直肌向颞侧移位至外直肌（lateral rectus muscle）的附着点处。将与外直肌毗邻的上直肌肌角采用可调缝线固定。随后，采用单臂6-0 Vicryl缝合线（single-armed 6-0 vicryl suture）制作后固定肌缝线，将其固定于上直肌与外直肌之间，固定位置距外直肌附着点约10mm，以将上直肌向颞侧牵拉。该缝线同样采用可调式设计。随后让患者取坐位，注视距其头部约10英尺处的目标，通过遮盖试验（cover testing）判断是否诱发了垂直斜视。若存在垂直斜视，则可放松后固定缝线。
<b>结果</b>: 本研究发现，当术后出现诱发垂直斜视或过矫（overcorrection）时，本术式可发挥良好的修正效果；上述不良事件的发生可能与后固定缝线及移位直肌诱发的组织束缚并发症相关。
<b>结论</b>: 本团队开发的联合可调式后固定肌缝线固定术的上直肌移位术，可为希望通过术中可调方案降低术后并发症（如诱发垂直斜视与过矫）风险的外科医师提供可靠的临床选择。