O'Neill Dillon C, Christensen Garrett V, Hillyard Bradley, Kawakami Jun, Tashjian Robert Z, Chalmers Peter N
Orthopaedic Resident, Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USA.
Research Associate, Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USA.
JSES Int. 2020 Dec 11;5(2):282-287. doi: 10.1016/j.jseint.2020.10.012. eCollection 2021 Mar.
The etiologies of glenohumeral osteoarthritis (GHOA) and eccentric glenoid wear within GHOA are unknown, but muscular imbalance may play a role. The purpose of the present study was to determine the relationship between deltoid muscle area, GHOA, and eccentric glenoid wear. We hypothesized that patients with GHOA would have overall deltoid atrophy as compared with controls and that increasing posterior deltoid areas would associate with glenoid retroversion in the Walch B-type (eccentric) GHOA group.
The study was a retrospective review of computed tomography imaging studies. We included a control group of subjects without GHOA and a group of individuals with GHOA before undergoing total shoulder arthroplasty. We assigned Walch types via consensus. Cross-sectional area was measured for the anterior and posterior deltoid musculature demarcated via the scapular line, normalized to the total deltoid area. Absolute and normalized total, anterior, and posterior deltoid areas were compared between controls and the entire GHOA group. Normalized anterior and posterior deltoid areas were compared between Walch A-type and B-type GHOA patients within the GHOA group. Univariate linear regression was used to evaluate for an association between glenoid retroversion and normalized posterior deltoid areas in controls, Walch A-type, and Walch B-type patients. Multivariate linear regression analysis was used to evaluate the effects of normalized posterior deltoid area, age, sex, and height on glenoid retroversion within the Walch B-type subgroup.
We included 99 patients with GHOA and 47 controls. The control and GHOA patients did not differ in absolute deltoid areas (21.8 ± 8.8cm vs. 20.6 ± 7.9cm; = .488). Patients with GHOA had a statistically significant increase in normalized posterior deltoid area (0.50 ± 0.10 vs. 0.46 ± 0.10; = .032) and a reciprocal decrease in normalized anterior deltoid area (0.50 ± 0.10 vs. 0.54 ± 0.10; = .040) compared with controls. Walch A-type and B-type patients did not differ in normalized posterior deltoid areas (0.50 ± 0.11 vs. 0.50 ± 0.10; = .780). Normalized posterior deltoid area positively associated with glenohumeral retroversion in Walch B-type GHOA (R = 0.102; = .020), a relationship maintained in multivariate linear regression, using gender, age, and height as covariates (standardized beta = 0.309, = .027).
GHOA is not associated with deltoid atrophy, calling into question the suggestion that periarticular muscular atrophy in GHOA is secondary to disuse. Increasing normalized posterior deltoid area associates with increased glenoid retroversion in patients with Walch B-type glenoid morphology. Muscular imbalance may play a role in the etiology or progression of the glenoid deformity observed in eccentric GHOA.
盂肱关节骨关节炎（GHOA）的病因以及GHOA中的偏心性肩胛盂磨损尚不清楚，但肌肉失衡可能起一定作用。本研究的目的是确定三角肌面积、GHOA和偏心性肩胛盂磨损之间的关系。我们假设与对照组相比，GHOA患者会出现整体三角肌萎缩，并且在Walch B型（偏心性）GHOA组中，三角肌后部面积增加会与肩胛盂后倾相关。
本研究是对计算机断层扫描成像研究的回顾性分析。我们纳入了一组无GHOA的对照组受试者以及一组在接受全肩关节置换术前患有GHOA的个体。我们通过共识确定Walch类型。测量通过肩胛线划定的三角肌前部和后部肌肉的横截面积，并将其归一化至三角肌总面积。比较对照组与整个GHOA组之间三角肌的绝对面积和归一化后的总面积、前部面积及后部面积。在GHOA组内，比较Walch A型和B型GHOA患者之间三角肌前部和后部面积的归一化值。采用单变量线性回归评估对照组、Walch A型和Walch B型患者中肩胛盂后倾与三角肌后部面积归一化值之间的相关性。采用多变量线性回归分析评估在Walch B型亚组中，三角肌后部面积归一化值、年龄、性别和身高对肩胛盂后倾的影响。
我们纳入了99例GHOA患者和47例对照组。对照组和GHOA患者的三角肌绝对面积无差异（21.8±8.8cm²对20.6±7.9cm²；P = 0.488）。与对照组相比，GHOA患者的三角肌后部面积归一化值有统计学显著增加（0.50±0.10对0.46±0.10；P = 0.032），而三角肌前部面积归一化值则相应降低（0.50±0.10对0.54±0.10；P = 0.040）。Walch A型和B型患者的三角肌后部面积归一化值无差异（0.50±0.11对0.50±0.10；P = 0.780）。在Walch B型GHOA中，三角肌后部面积归一化值与盂肱关节后倾呈正相关（R = 0.102；P = 0.020），在以性别、年龄和身高作为协变量的多变量线性回归中，这种关系依然存在（标准化β = 0.309；P = 0.027）。
GHOA与三角肌萎缩无关，这对GHOA中关节周围肌肉萎缩是废用性的这一观点提出了质疑。在具有Walch B型肩胛盂形态的患者中，三角肌后部面积归一化值增加与肩胛盂后倾增加相关。肌肉失衡可能在偏心性GHOA中观察到的肩胛盂畸形的病因或进展中起作用。
