The scapular glenopolar angle: standard values and side differences.

Area of Science:

• Orthopedics
• Radiology
• Anatomy

Background:

• The glenopolar angle (GPA) is a critical measurement for assessing scapular anatomy.
• Accurate GPA measurement is essential for diagnosing and managing shoulder pathologies.

Purpose of the Study:

• To determine normal glenopolar angle (GPA) values using bone specimens.
• To compare GPA values obtained from bone specimens with those from various radiological views and CT examinations.

Main Methods:

• GPA values were measured on 100 dry scapulae bone specimens.
• Measurements were also taken from 50 AP shoulder radiographs, 50 Neer I views, 50 AP chest radiographs, and 20 3D CT reconstructions.

Main Results:

• Bone specimens yielded an average GPA of 42.3° (side-to-side difference 1.6°).
• 3D CT reconstructions showed an average GPA of 43.0° (side-to-side difference 1.4°).
• Neer I views averaged 40.6°, while AP shoulder and chest radiographs showed significantly lower values (35.9° and 37.1°, respectively).

Conclusions:

• GPA measurement accuracy is method-dependent.
• 3D CT reconstructions and Neer I views closely replicate bone specimen GPA values.
• AP radiographs provide statistically lower GPA measurements, making 3D CT and Neer I views the preferred methods for precise GPA assessment.