反置式肩關節置換術個案之肩膀運動學及內轉缺失之因子

Abstract

背景：反置式肩關節置換術廣泛應用於修復旋轉袖破裂關節病變和嚴重肩關節炎等情況。雖然反置式肩關節置換術後在功能性活動範圍，尤其是屈曲和外展方面的提升較為常見，但內轉活動度的恢復卻較難預測。手背觸背測試常用於評估內轉角度，然而其準確性可能不足。肩胛骨運動學對反置式肩關節置換術患者的手背觸背動作起著至關重要的作用，但目前尚未完全理解。本研究聚焦於手背觸背動作中肩胛骨運動的角色。 目的：(1) 描述反置式肩關節置換術患者相較於年齡及慣用手匹配的對照組在手背觸背動作和手臂上舉時肩胛骨及肱骨的運動學特徵；(2) 識別於內轉關節活動度受損相關的潛在因素。 方法：本橫斷面觀察性研究招募了31名反置式肩關節置換術後患者及28名對照組。收集受試者的人口統計資料、肩關節被動關節活動度、手背觸背動作量表（手背觸背比值）、以及患者報告的結果，所有資料均由同一評估員測量。隨後，使用電磁追蹤系統測量肩胛骨在各種功能性動作（有無負重的手臂上舉）中的運動學。採用雙因子變藝術分析檢測兩組間的肩胛骨運動學差異，並使用線性回歸分析反置式肩關節置換術患者手背觸背動作的影響因素。 結果：本橫斷面觀察性研究共納入31名反置式肩關節置換術後患者及28名對照組。在有無負重的手臂上舉動作中，兩組在肩胛骨三維運動（特別是上旋和後傾）方面存在顯著差異（p<0.05）；然而，在手背觸背動作中未發現顯著差異。反置式肩關節置換術組手背觸背比值的回歸方程式如下： 手背觸背比值 = 1.036 + 0.016×（BMI）−0.005×（ERabd45）−0.007×（IRabd90） 其中，BMI為體重指數，ERabd45為手臂外展45度時的肩關節外旋，IRabd90為手臂外展90度時的肩關節內轉。 臨床意義：闡明反置式肩關節置換術患者手背觸背動作中的肩胛骨與肱骨運動，並識別與手背觸背動作相關的因素，可幫助臨床醫生制定最佳策略，以提升反置式肩關節置換術患者的滿意度。 結論：反置式肩關節置換術患者在手臂上舉時展現出更多的肩胛骨上旋和後傾作為代償策略。對於手背觸背動作，除了肩關節內轉，外旋也是一個重要的影響因素。

Background: Reverse Total Shoulder Arthroplasty (RTSA) is widely used for conditions like cuff-tear arthropathy and severe shoulder arthritis. Although gains in functional range of motion (ROM), especially in flexion and abduction, are common post-RTSA, internal rotation (IR) ROM remains less predictable. The hand-behind-back (HBB) test is often used to measure IR, though it may have lacked accuracy. Scapular kinematics play a critical role in HBB movement for RTSA patients yet are not fully understood. This study focused on the role of scapular movement during HBB. Purposes: Aims of this study were:(1) to characterize scapular and humeral kinematics in patients with RTSA relative to involved hand- and age- matched control group during HBB movement and elevation; (2) identify potential factors related to impaired IR ROM. Methods: Thirty-one subjects after RTSA and 28 controls were recruited in this cross-sectional observational study. Subjects’ data included demographic data, GH joint passive ROM (pROM), HBB movement scale (HBB ratio), patient-reported outcomes were collected by the same assessor. After that, scapular kinematics during various functional movements (arm elevation with and without weight) were measured by using an electromagnetic tracking system. Two-way ANOVA will be used to test scapular kinematics between two groups and linear regression were be used to identify the factors HBB movement in patients with RTSA. Results: Thirty-one subjects after RTSA and 28 controls were recruited in this cross-sectional observational study. Significant differences were found between two groups in the three-dimensional scapular movements during arm elevation with and without weight, specifically in upward rotation (6.81±2.65, p<0.05) and posterior tilting (5.24±3.93, p<0.05). However, there was no significant difference in HBB movement. The regression equation of HBB ratio in RTSA group was as follows: HBBRTSA ratio= 1.036 +0.016×(BMI) −0.005×(ERabd45) −0.007×(IRabd90), in which BMI indicated body mass index; ERabd45 indicated GH joint external rotation when arm abduction 45 degrees; IRabd90 indicated GH joint internal rotation when arm abduction 90 degrees. Clinical significance: Clarifying scapular and humeral motions during HBB movement in patients with RTSA and identifying factors associated with HBB movement can guide clinicians to make optimal decisions to enhance patient satisfaction following RTSA surgery. Conclusions: Patients with RTSA exhibited greater scapular upward rotation and posterior tilting as compensatory strategies during arm elevation. For HBB movement, in addition to considering GH joint IR, ER should also be a contributing factor.