CADAVERIC AND TC 3D RECONSTRUCTION STUDY OF THE MORPHOLOGY OF THE SCAPULA AND ITS APPLICATION TO REVERSED PROSTHESES IMPLANTATION

Abstract

Introduction: Reversed prostheses implantation requires screwing of the glenoid component with prefixed angles. This study is to determine anatomical angles of scapula that take part in reversed prostheses implantation.

Material and method: Seventy-three 3-dimensional computed tomography of the scapula and 108 scapular dry specimens were analyzed. Mean age of the CT-3D serie was of 52.59 years old (ranging from 16 to 84). There were 46 females and 27 males. The following measures were made on each patient: length of the neck of the inferior glenoid, angle between the glenoid surface and the upper posterior column of the scapula, angle between the major craneo-caudal glenoid axis and the base of the coracoid process and angle between the major craneo-caudal glenoid axis and the upper posterior column of the scapula. Measures were performed in the AP view as well as in the posterior view of the scapula.

Results: The length of the neck of the anterior glenoid was classified into two groups named ‘short-neck’ and ‘long-neck’ for both three-dimensional computed tomography and cadaveric scapulas with statistically significant differences between both groups (p< 0,001 for the three-dimensional computed tomography scapulas and p=0,034 for the cadaveric group). The angle between the glenoid surface and the upper posterior column of the scapula was also classified into two different types: type I (52° ranging from 48° to 57°) and type II (64° ranging from 60° to 70°) with statistically significant differences between both groups (p< 0,001 for the three-dimensional computed tomography scapulas and p< 0,001 for the cadaveric group). The angle between the major craneo-caudal glenoid axis and the center of the base of the coracoid process averaged 18,25° (ranging 13° from to 27°). The angle between the major craneo-caudal glenoid axis and the upper posterior column of the scapula averaged 8° (ranging 5° from to 18°).

Conclusions:

• - scapulas can be classified into two groups regarding the angle between the glenoid surface and the upper posterior column of the scapula with significant differences between them.

• - two different lengths of the neck of the inferior glenoid body have also been differentiated in the anterior as well as in the posterior faces of the scapula.

• - the base of the coracoid process is not in line with the posterior column of the scapula.

• - three-dimensional computed tomography of the scapula constitutes and important tool when planning reversed prostheses implantation.