Morphometric Analysis of Glenopolar Angle of the Scapula in Indian Population

The glenopolar angle (GPA), usually ranges from 30° to 45°. GPA measures the tilt of the plane of the glenoid cavity in relation to the axis of the body of the scapula passing from the superior pole of the glenoid cavity to the inferior angle of the scapula. It is essential to assess the results of surgeries for dislocated shoulders. Worse long-term outcomes can arise from glenoid misalignment in scapular neck fractures. When evaluating prognosis and planning therapy for shoulder injuries including scapular fractures, GPA assessment is essential. Still, there is a dearth of data on the normal range of GPA and its contributing elements, which calls for more study. The purpose of this study is to determine typical GPA values by utilizing radiographs and a sizable sample of scapular bone specimens.

In this study, the GPA was assessed in 50 chest radiographs of anteroposterior (AP) view and Neer's view of individuals as well as 100 dried scapulae of any gender. The mean GPA obtained using the various methods was then statistically compared.

All scapulae had an average GPA of 42.6°. Twenty-nine scapulae had GPA observations higher than 45°, with an average of 47.2°. Twenty-seven scapulae had GPA measurements below 40°, averaging 37.3°. Right-sided 62 scapulae with an average GPA of 43.1° were present. Thirty-eight of left-side scapulae had a GPA of 41.7° on average. It was determined that the 1.6° mean difference in GPA between the two groups was not statistically significant. The Kolmogorov-Smirnov test verified that the GPA data had a normal distribution. The homogeneity of variances across various measuring techniques was confirmed using Levene's test. The average GPA measured using the dry scapula approach was 42.6°, the average GPA measured using the AP view was 39.8°, and the average GPA measured using the Neer I view was 42.3°. The GPA means from these three approaches differed considerably (p=0.0014) according to a one-way Analysis of Variance (ANOVA). Fisher's least significant difference post hoc testing showed that the scapular bone specimens and the Neer I view revealed significantly higher GPA values than AP shoulder radiographs. The GPA values obtained from the osteological group and the Neer I perspective had a mean difference of 0.21°, which was practically identical and suggested that there was no statistically significant difference between these approaches.

In order to diagnose and treat a variety of shoulder joint diseases, this study estimates the normal values of scapular GPA. Furthermore, it offers support for improved implant design in the context of Indian shoulder joint replacement and repair. Using every measurement technique, the GPA values on the right and left sides did not differ significantly. GPA results from various measuring methods varied significantly, which emphasizes the significance of methodological consistency in clinical and research settings.