Introduction

While lateralization of the glenohumeral center of rotation during reverse shoulder arthroplasty (RSA) has benefits of maintaining tension on the remaining rotator cuff and decreasing implant impingement on the glenoid, few clinical studies have evaluated the isolated effect of glenoid lateralization in RSA. The purpose of this study was to evaluate if clinical outcomes are affected by isolated glenosphere lateralization using a single implant design.

Methods

A retrospective review from a multicenter shoulder arthroplasty research database was performed between 2011 and 2018 using a single implant system to perform this case-controlled study. Inclusion criteria included primary RSAs with adequate preoperative and postoperative active and passive range of motion (ROM) measurements, outcome scores, and a minimum two-year follow-up. Revision shoulder arthroplasties and RSA for fractures were excluded from analysis. 102 RSAs (61 females, 41 males) using a +4 mm lateralized glenosphere were compared to 102 sex, age, and glenosphere diameter matched control shoulders with standard glenospheres (whose center of rotation (CoR) is 2 mm lateral to the glenoid fossa). The mean age at surgery was 70.4 years. Mean follow up was 43.6 + 18.9 months. All RSAs were performed with the same implant system (Equinoxe, Exactech, Gainesville, FL). Clinical outcome measures included ROM, ASES, Constant, UCLA, SST, SPADI scores, and VAS pain scores. We used the chi-squared test and Fisher exact test for bivariate analysis and the student t-test for continuous variables.

Results

Both groups were of similar average age and follow-up. They also had comparable rates of prior surgery and comorbidities. The lateralized glenosphere group had a slightly higher BMI (31.2 vs. 29.2, p = 0.04). Both groups demonstrated significant improvements in all outcome scores that exceeded the MCID and the SCB. The groups demonstrated similar preoperative, postoperative and improvements in ROM as well as outcome scores. The overall complication rate was similar between groups (4% in lateralized and 5% in controls, p = 0.73). Scapular or acromial fractures differences were not statistically significant between groups (1% in lateralized group vs. 3% in standard group, p = 0.31). Scapular notching was more frequent in the standard group compared to the lateralized group (9% vs. 2%, p = 0.03).

Conclusion

In a medialized glenosphere/lateralized humerus design, a +4 mm lateralized glenosphere provided no significant advantage in postoperative pain, ROM, or outcome scores. However, lateralized glenospheres did demonstrate significantly lower scapular notching rates.

Level of evidence

III; retrospective cohort comparison; treatment study.

中文翻译：

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孤立的盂球偏侧化会影响反向肩关节置换术的结果吗？

介绍

虽然在反向肩关节置换术 (RSA) 期间将盂肱旋转中心偏侧化有利于保持剩余肩袖的张力并减少植入物对关节盂的撞击，但很少有临床研究评估 RSA 中关节盂偏侧化的孤立效果。本研究的目的是评估临床结果是否受到使用单一种植体设计的孤立盂球偏侧化的影响。

方法

在 2011 年至 2018 年期间，使用单一植入系统进行了多中心肩关节置换术研究数据库的回顾性研究，以进行这项病例对照研究。纳入标准包括具有充分的术前和术后主动和被动运动范围 (ROM) 测量、结果评分和至少两年随访的主要 RSA。肩关节翻修术和 RSA 骨折被排除在分析之外。102 名 RSA（61 名女性，41 名男性）使用 +4  mm 外侧化盂球与 102 名性别、年龄和盂球直径匹配的对照肩与标准盂球（其旋转中心 (CoR) 距关节窝外侧 2 mm）进行 比较. 手术时的平均年龄为 70.4 岁。平均随访为 43.6  + 18.9 个月。所有 RSA 均使用相同的植入系统（Equinoxe、Exactech、Gainesville、FL）进行。临床结果指标包括 ROM、ASES、Constant、UCLA、SST、SPADI评分和 VAS 疼痛评分。我们对双变量分析使用卡方检验和 Fisher 精确检验，对连续变量使用学生 t 检验。

结果

两组的平均年龄和随访情况相似。他们的既往手术和合并症发生率也相当。侧化盂球组的 BMI 略高（31.2 与 29.2，p  = 0.04）。两组在所有结果得分上均表现出显着改善，超过了 MCID 和 SCB。这些组在 ROM 以及结果评分方面表现出相似的术前、术后和改善。组间的总体并发症发生率相似（侧化组为 4%，对照组为 5%，p = 0.73）。肩胛骨或肩峰骨折组间差异无统计学意义（偏侧组 1% vs. 标准组 3%，p =     0.31）。与侧化组相比，标准组的肩胛切迹更常见（9% 对 2%，p  =  0.03）。

结论

在内侧盂球/外侧肱骨设计中，+4 mm 外侧盂球在术后疼痛、ROM 或结果评分方面没有显着优势。然而，侧化盂球确实表现出明显较低的肩胛切迹率。 

证据等级

三；回顾性队列比较；治疗研究。