Morphometric Study of Suprascapular Notch and Its Safe Zone in Indian Population

Objectives: The suprascapular notch is located on the lateral part of the superior border of the scapula. The anatomical variation of the notch is considered as one of the causes of suprascapular nerve entrapment. In the present study, we tried to evaluate the morphology and morphometry of the suprascapular notch of Indian human dry scapulae and to compare it with scapula morphometry, which is essential to understand and treat different causes of suprascapular nerve entrapment and to obtain a safe zone, which would be useful to avoid iatrogenic nerve lesion during open arthroscopic surgeries and help in designing implants for the shoulder joint. Methods:This is an observational study, with a total of 200 human dry scapulae being observed, examined and studied in detail. The type of suprascapular notch was noted as per the description given by Rengachary et al. Digital Vernier Caliper was used for classical osteometric measurements of suprascapular notch parameters, posterior limit and posterosuperior limit of safe zone along with length and width of scapulae. A statistical data analysis was done. Results:Out of the 200,scapulae examined by us, 172 (86%) showed the presence of suprascapular notch, while nine (4.5%) showed partial ossification and 19 (9.5%) complete ossification. Six types of suprascapular notches were observed: type I,51 (25.5%); type II 45 (22.5%); type III 64 (32%); type IV 11 (5.5%); type V 9 (4.5%), and type VI 20 (10%). Type III notch was more prevalent. The study showed a moderate positive linear correlation between the width of the scapula and the safe zone of type III notch, respectively. Conclusion: Anatomical knowledge about the types of suprascapular notch and measurements is very helpful in the diagnosis and management of cases with shoulder pain due to suprascapular nerve entrapment and also while administering suprascapular nerve blocks for surgeries involving the shoulder region. Safe zone distances are very important for avoiding iatrogenic suprascapular nerve injuries during shoulder surgical procedures.