Morphometry of the Acromion Process in Dry Human Scapulae and Its Clinical Implications: A Cross-sectional Study

Abstract

Introduction: The coracoacromial arch, which extends laterally over the shoulder joint, is formed by the acromion process, coracoid process, and coracoacromial ligament. The acromion process plays an important role in shoulder joint formation. Morphological variations of the acromion process play a key role in determining the subacromial space. Acromioplasty is an important step in rotator cuff repair. Aim: To investigate the morphometry of the acromion process in dry human scapulae and determine the various types of acromion processes. Materials and Methods: An observational cross-sectional study was conducted in the Department of Anatomy at NRI Medical College and General Hospital, Chinakakani, Guntur, Andhra Pradesh, India. The study duration was one year and four months, from November 2020 to March 2022. A total of 100 dry human scapulae (50 right and 50 left) of unknown age and gender were included. Various types of acromion processes were identified. Measurements were taken using a digital vernier caliper (accurate to 0.01 mm) and protractor to measure parameters such as length, breadth, and thickness of the acromion process, acromiocoracoid distance, acromioglenoid distance, height of the coracoacromial arch, acromial slope, and acromial tilt. The data were analysed using Statistical Package for Social Sciences (SPSS) version 24.0. Mean, Standard Deviation (SD), and range were calculated for each morphometric parameter. Results: Three types of acromion processes were observed: type I (31%), type II (48%), and type III (21%). The mean length, breadth, and thickness of the acromion process were 43.21±2.82 mm, 25.48±2.56 mm, and 6.84±1.24 mm, respectively. The mean acromiocoracoid distance, acromioglenoid distance, and height of the coracoacromial arch were 39.87±7.63 mm, 27.34±3.58 mm, and 21.52±1.98 mm, respectively. The mean acromial slope and acromial tilt observed were 32.34±4.62° and 37.46±6.37°, respectively. Conclusion: The present study provides data on the shape, dimensions, slope, tilt, and various distances of the acromion process in dry human scapulae. The majority of the scapulae on both sides exhibited type II acromion process.