Caubère Alexandre, Boux de Casson François, Jung Amaury, Werthel Jean-David, Vervaecke Alexander J, Gauci Marc-Olivier
Hôpital d'Instruction des Armées Sainte-Anne, Toulon, France.
Blue Ortho, Meylan, France.
Int Orthop. 2025 Sep;49(9):2111-2122. doi: 10.1007/s00264-025-06619-9. Epub 2025 Jul 21.
The aim of this study was to define the variability of the scapulohumeral position during preoperative Computed Tomography (CT) acquisition and to evaluate its influence on angular lateralization and distalization measurements. We hypothesized that the preoperative resting arm position, in terms of humeral abduction, flexion and internal rotation, would vary significantly between patients and that this variability would influence the lateralization (LSA) and distalization shoulder angle (DSA).
We analyzed a prospectively collected database of preoperative de-identified CT scans from a single Total Shoulder Arthroplasty (TSA) planning system (Equinoxe, Exactech GPS, Blue-Ortho), including all cases with scapular and humeral segmentation. Validated three-dimensional (3D) bone models were used to compute and automatically position scapular and humeral landmarks. These included: the superior glenoid tubercle; the most lateral border of the acromion and the most lateral border of the greater tuberosity. The position of the humerus relative to the scapula was automatically calculated, allowing the angles of abduction, flexion and internal rotation of the scapulohumeral joint to be assessed. Additionally, the potential relationship between the body mass index (BMI) and the resting arm position was assessed. Finally, LSA and DSA were calculated. A multiple linear regression analysis was performed to assess the relationship between the humeral position and the LSA and DSA.
A total of 21,863 patients were included. Preoperative humeral positioning relative to the scapula showed a mean abduction of 10.3°±12.4 (-14.0°; 36.6°), mean flexion of 3.9°±8.9 (-16.0°; 26.1°) and mean internal rotation of 6.5°±18.9 (-41.4°; 48.9°). The preoperative median of LSA and DSA were 87.4°±14.3° and 43°±12.4, respectively. Among the independent variables, abduction showed the strongest negative correlation with LSA (β = -0.2998, p < 0.0001), followed by flexion (β = -0.04342, p < 0.0001). Internal rotation was positively correlated with LSA (β = 0.1229, p < 0.0001). For DSA, abduction had a weak positive influence (β = 0.04321, p < 0.0001), while flexion (β = -0.04302, p < 0.0001) and internal rotation (β = -0.04654, p < 0.0001) were negatively associated. Notably, a 10° variation in abduction, flexion or internal rotation led to a -3°, -0.4° and + 1.2° change in LSA, respectively, whereas DSA was minimally affected, with variations limited to + 0.4°, -0.4° and - 0.5°, respectively.
The resting arm position during preoperative CT scans varies significantly, potentially affecting the preoperative planning of TSA. The main findings of this study suggest that there exists a weak correlation between the initial scapulohumeral position and the LSA/DSA measurements.
Level IV. Case series with no comparison group.
本研究的目的是确定术前计算机断层扫描（CT）采集过程中肩胛肱骨位置的变异性，并评估其对角度侧方移位和远端移位测量的影响。我们假设，就肱骨外展、屈曲和内旋而言，患者术前的静息手臂位置会有显著差异，且这种变异性会影响侧方移位（LSA）和远端移位肩角（DSA）。
我们分析了一个前瞻性收集的数据库，该数据库来自单一的全肩关节置换术（TSA）规划系统（Equinoxe，Exactech GPS，Blue-Ortho）的术前匿名CT扫描，包括所有肩胛和肱骨分割的病例。使用经过验证的三维（3D）骨模型来计算并自动定位肩胛和肱骨标志点。这些标志点包括：肩胛盂上结节；肩峰最外侧缘和大结节最外侧缘。自动计算肱骨相对于肩胛骨的位置，从而评估肩胛肱骨关节的外展、屈曲和内旋角度。此外，评估了体重指数（BMI）与静息手臂位置之间的潜在关系。最后，计算LSA和DSA。进行多元线性回归分析以评估肱骨位置与LSA和DSA之间的关系。
共纳入21863例患者。术前肱骨相对于肩胛骨的位置显示平均外展10.3°±12.4（-14.0°；36.6°），平均屈曲3.9°±8.9（-16.0°；26.1°），平均内旋6.5°±18.9（-41.4°；48.9°）。LSA和DSA的术前中位数分别为87.4°±14.3°和43°±12.4°。在自变量中，外展与LSA的负相关性最强（β = -0.2998，p < 0.0001），其次是屈曲（β = -0.04342，p < 0.0001）。内旋与LSA呈正相关（β = 0.1229，p < 0.0001）。对于DSA，外展有较弱的正向影响（β = 0.04321，p < 0.0001），而屈曲（β = -0.043）和内旋（β = -0.04654，p < 0.0001）呈负相关。值得注意的是，外展、屈曲或内旋10°的变化分别导致LSA变化-3°、-0.4°和+1.2°，而DSA受影响最小，变化分别限于+0.4°、-0.4°和-0.5°。
术前CT扫描期间的静息手臂位置差异显著，可能影响TSA的术前规划。本研究的主要发现表明，初始肩胛肱骨位置与LSA/DSA测量之间存在弱相关性。
IV级。无对照组的病例系列。
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