Background

Minimally-invasive Chevron and Akin osteotomy (MICA) represents the third-generation percutaneous hallux valgus surgery which is characterized by an extra-articular osteotomy, stable internal fixation and a high potential for correction. Compared to other percutaneous techniques of the foot, MICA is generally regarded as an advanced and demanding surgical procedure with a flat learning curve. The aim of this study is to analyze a single-surgeons experience with his first 50 consecutive MICA procedures.

Methods

Between May 2018 and February 2021, 50 consecutive MICA procedures performed by the author with the "K-wires-First technique" were prospectively analyzed focusing on surgery duration, number of fluoroscopies, correction results and surgery-associated complications. A modification of the original MICA technique as described by its inaugurators Redfern and Vernois allows the use of a standard-sized C-arm and aims to reduce revison rates and conversion to open surgery by placing the guidewires prior to performing the osteotomy.

Results

The average surgery time for all MICA procedures was 46.8 min (SD 12.1, range 31–90 min). The average amount of fluoro shots required to perform MICA was n = 126.6 (SD 40.8, range 65–231). Comparing the preoperative and 6-week postoperative radiographs, the IMA decreased after MICA by a mean of 10.8° from 16.2° to 5.4° and the HVA by a mean of 22.1° from 30.6° to 8.5°. One case required intraoperative conversion to open hallux correction. There were 4 feet in three patients with secondary screw removal of the Chevron fixation due to prominent proximal screw tips.

Conclusions

Although the learning curve of 3rd generation MICA is flat and requires specific training and intensive practice, the rate of complications is not elevated compared to other percutaneous hallux valgus techniques. Strict adherence to the principles of 3rd generation MICA with stable fixation and meticulous intraoperative control of each surgical step helps to reduce surgery-associated complications. The learning curve showed a continous improvement in regard to surgery time and use of fluoroscopy. After 40 procedures, the surgery time consistently dropped under 45 min and required less than 100 fluoro-shots. The modified surgical technique may help reduce Chevron screw mal-positioning when using large C-arm fluoroscopy for this procedure.

中文翻译：

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第三代微创Chevron and Akin截骨术（MICA）经皮学习曲线

背景

微创 Chevron and Akin 截骨术 (MICA) 代表第三代经皮拇外翻手术，其特点是关节外截骨、稳定的内固定和高矫正潜力。与足部的其他经皮技术相比，MICA 通常被认为是一种先进且要求高的外科手术，学习曲线平坦。本研究的目的是分析一名外科医生在前 50 次连续 MICA 手术中的经历。

方法

在 2018 年 5 月至 2021 年 2 月期间，对作者使用“克氏针优先技术”进行的 50 次连续 MICA 手术进行了前瞻性分析，重点关注手术持续时间、透视次数、矫正结果和手术相关并发症。其发起人 Redfern 和 Vernois 描述的对原始 MICA 技术的修改允许使用标准尺寸的 C 形臂，旨在通过在截骨术前放置导丝来降低修正率和转换为开放手术。

结果

所有 MICA 手术的平均手术时间为 46.8 分钟（SD 12.1，范围 31-90 分钟）。执行 MICA 所需的平均荧光照射量为 n = 126.6（SD 40.8，范围 65-231）。比较术前和术后 6 周的 X 光片，MICA 后 IMA 从 16.2° 平均减少 10.8° 至 5.4°，HVA 平均减少 22.1° 从 30.6° 至 8.5°。1 例需要术中转为开放式拇趾矫正。由于突出的近端螺钉尖端，三名患者有 4 只脚需要二次移除 Chevron 固定螺钉。

结论

虽然第 3 代 MICA 的学习曲线平坦，需要专门的培训和强化练习，但与其他经皮拇外翻技术相比，并发症的发生率并未升高。严格遵守第 3 代 MICA 的原则，稳定的固定和术中对每个手术步骤的精细控制有助于减少手术相关并发症。学习曲线显示在手术时间和透视使用方面持续改进。40 次手术后，手术时间持续下降到 45 分钟以下，并且需要少于 100 次荧光照射。当使用大型 C 型臂透视进行此手术时，改进的手术技术可能有助于减少 Chevron 螺钉的错误定位。