Background: Knowledge of the normal anatomy and the possible variations of the scapula are beneficial in early diagnosis and proper management of shoulder disorders to evade its disabling complications as well as to avoid injury of the important neurovascular structures around the scapula.
Aim of work: To estimate the prevalence of the anatomical variations of the scapula and their clinical implications and to calculate the acromion index and acromio-humeral interval; which could be helpful in the management of rotator cuff diseases.
Material and Methods: One hundred dried scapulae were studied for morphological and morphometric variations. A radiological study was done by calculating both acromion index and acromio humeral interval in one hundred radiographs.
Results: Four types of acromion were observed: type-1(flat), type-2(curved), type-3 (hooked) and type-4 (convex downwards). Four shapes of acromion were identified: cobra-head, triangular, rectangular and square. Acromion thickness ranged from 5 to 11mm.Acromion length ranged from 24 to 65mm.Acromion width ranged from 18 to 40mm.Acromio-glenoid distance (AGD) ranged from 20 to 40mm.Acromio-coracoid distance ranged from 22 to 68mm. Suprascapular notch shapes included U-shaped, V-shaped, J-shaped and W-shaped notch that was encountered for the first time in literature. Suprascapular notch types were: type-1 (absent notch), type-2 (wide and shallow notch), type-3 (narrow and deep notch), type-4 (a bony foramen) and Type-5 (a notch is present above a bony foramen). Anatomical variations causing snapping scapula were lushka tubercle and teres major process. Acromion index (AI) ranged from 0.63 to 0.71. Acromio-humeral interval (AHI) ranged from 7 to 14mm.
Conclusion: The anatomical variations of the scapula should be considered by orthopaedicians, as it influences the technique and instrumentation in open or arthroscopic surgical procedures.