Morphometric analysis of glenoid cavity of dry scapulae and its role in shoulder prosthesis

Background: The lateral angle of scapula becomes truncated and broadened and form the glenoid cavity which shows variable morphology. There is a notch present on its anterosuperior part which gives its different shape. When this glenoid notch is indistinct its shape is piriform, when it is distinct it looks like inverted comma shape and when it is absent its oval shape. The shoulder joint is one among the most commonly dislocated joints in the body. The fracture of glenoid with dislocations is very common in the trauma. The detail knowledge about variation in anatomy of glenoid cavity like different shape, size and dimensions are important during designing and fitting of glenoid component for total shoulder arthroplasty. The objective of present study was to obtain anthropometric data of scapulae and the glenoid cavity specifically the diameters and various shape of glenoid belongs to population of Bihar and compare it to findings from other races of the world. Methods: The present study was a cross sectional study which has been carried out on 228 undamaged dry adult human scapulae in which 126 belongs to right side and 102 belongs to left side. The age and gender of the bones used in the study was not predetermined. Results: The most common shape of glenoid cavity recorded in the present study was pear shape (50.44%) followed by inverted comma shape (35.96%). The least common shape was oval (13.6%). The mean length of scapula was observed as 135.07±14.23mm, the mean breadth of scapula was 97.55±9.63 mm, the mean supero inferior glenoid diameter was 35.80±3.14mm, the mean antero posterior glenoid diameter 1 was 23.63±2.50mm, and the mean antero posterior glenoid diameter 2 was 16.17±2.24mm and mean glenoid cavity index was 66.40±8.14%. In all the above measurements bilateral differences was not statistically significant. Conclusions: The knowledge about the different shape and dimensions of glenoid are very important during designing and fitting of glenoid component for total shoulder arthroplasty. It is also helpful during evaluation of different pathological conditions like rotator cuff disease, osteochondral defects and Bankart lesion. Since the present study is conducted on a limited number of scapulae further cadaveric, radiological and clinical studies are indicated.