Background

Ulna distraction by monolateral external fixator (MEFix) is a good option for the treatment of Masada type I and IIb deformities in children with hereditary multiple exostoses (HMEs). However, there is no consensus regarding where to perform ulnar osteotomy. Our hypothesis is that osteotomy at the proximal third of the ulna and progressive distraction with MEFix can simultaneously correct elbow and wrist deformities in patients with HME.

Methods

We retrospectively reviewed patients with HME who underwent ulna distraction osteogenesis from June 2014 to March 2019. The carrying angle (CA), radial articular angle (RAA), ulnar variance (UV), radial variance (RV) and range of motion (ROM) of the affected forearm and elbow were clinically assessed before lengthening and at the last follow-up visit. The total ulna lengthening distance (LD) and radiographic outcome were also recorded.

Results

Nineteen patients (20 forearms) with HME aged 9.1 ± 2.4 years at the time of surgery were retrospectively reviewed. The mean follow-up period was 26.1 ± 5.6 months. There were 11 patients (12 forearms) with Masada type I deformities and eight patients (8 forearms) with Masada type IIb deformities. Patients with type IIb deformity had higher RV, lower CA values, less elbow flexion and forearm pronosupination than those with type I deformity (p < 0.05); RV was an independent risk factor for radial head dislocation, with the cut off at RV > 15.5 mm. The mean LDs in patients with type I and type IIb deformities were 33.6 ± 6.6 mm and 41.4 ± 5.4 mm, respectively. The mean CA, UV, RV, forearm pronation and ulna deviation at the wrist improved significantly following surgery in all patients. In particular, five of eight patients (62.5%) with type IIb deformities had concentric reduction of the radiocapitellar joint, while no radial head subluxation was detected in patients with type I deformities at the last follow-up. Three complications were recorded: two pin-track infections and one delayed union.

Conclusions

Distraction osteogenesis at the proximal third of the ulna provides satisfactory clinical and radiological outcomes in patients with Masada type I and IIb deformities. Early treatment of Masada type I deformities is indicated before progression to more complex type IIb deformities.

中文翻译：

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尺骨近端 1/3 牵引成骨术治疗遗传性多发性外生骨疣儿童 Masada I/IIb 型畸形：20 例回顾性研究

背景

单侧外固定器 (MEFix) 尺骨牵引是治疗遗传性多发性外生骨疣 (HME) 儿童马萨达 I 型和 IIb 型畸形的良好选择。然而，对于在哪里进行尺骨截骨术，目前还没有达成共识。我们的假设是，在尺骨近端三分之一的截骨术和 MEFix 进行性牵引可以同时矫正 HME 患者的肘部和腕部畸形。

方法

我们回顾性分析了 2014 年 6 月至 2019 年 3 月接受尺骨牵引成骨术的 HME 患者。携带角（CA）、桡关节角（RAA）、尺骨方差（UV）、桡骨方差（RV）和活动范围（ROM）受影响的前臂和肘部在延长前和最后一次随访时进行了临床评估。还记录了总尺骨延长距离 (LD) 和影像学结果。

结果

对手术时年龄为 9.1 ± 2.4 岁的 19 名 HME 患者（20 条前臂）进行了回顾性分析。平均随访时间为 26.1 ± 5.6 个月。有 11 名患者（12 条前臂）患有 Masada I 型畸形，8 名患者（8 条前臂）患有 Masada IIb 型畸形。与 I 型畸形患者相比，IIb 型畸形患者具有更高的 RV、更低的 CA 值、更少的肘部屈曲和前臂旋后（p < 0.05); RV 是桡骨头脱位的独立危险因素，在 RV > 15.5 mm 处截断。I 型和 IIb 型畸形患者的平均 LD 分别为 33.6 ± 6.6 mm 和 41.4 ± 5.4 mm。所有患者手术后的平均 CA、UV、RV、前臂旋前和手腕尺骨偏差均有显着改善。特别是，8 名 IIb 型畸形患者中有 5 名 (62.5%) 的桡小头关节向心复位，而 I 型畸形患者在末次随访时未发现桡骨头半脱位。记录了三种并发症：两种针道感染和一种延迟愈合。

结论

尺骨近端 1/3 处的牵引成骨术为 Masada I 型和 IIb 型畸形患者提供了令人满意的临床和影像学结果。在进展为更复杂的 IIb 型畸形之前，需要早期治疗 Masada I 型畸形。