The anatomic relationship between the morphology of the greater tubercle of the humerus and the insertion of the infraspinatus tendon

Background: The objective of this study was to evaluate the topographic relationship between the morphology of the greater tubercle and the insertion of the tendon of the infraspinatus. Materials and methods: First, we defined an impression of the greater tubercle, which has not been recognized in classic textbooks, as the "lateral impression" and then measured the dimensions of the "lateral impression" of the greater tubercle in 71 samples of dry bone of humeri. Next, we examined 16 cadaveric humeri with rotator cuff tendons by micro-computed tomography to analyze the positional relationship between the lateral impression and the infraspinatus tendon. Results: In all samples of dry bones, the lateral impression could be identified as a triangle shape. The lateral impression was composed of the border with the highest impression (mean, 6.3mm), the border with the middle impression (mean, 5.0mm), and the border with the lateral wall of the greater tubercle (mean, 8.5mm). In all samples of humeri with rotator cuffs, we could confirm the lateral impression, and the border between the highest impression and the lateral impression corresponded to the anterior border of the insertion of the infraspinatus tendon. Conclusion: We propose a new anatomic concept of the lateral impression that could enable the precise diagnosis of and facilitate repair techniques for infraspinatus tear, according to specific anatomic characteristics, by applying 3-dimensional computed tomography assessment preoperatively.