RADIOGRAPHIC DETERMINATION OF NORMAL RANGE VALUES OF ACROMIOCLAVICULAR JOINT SPACE IN NIGERIAN POPULATION

Background: Acromioclavicular joint space is one of the most common injuries of the shoulder region. Accurate diagnosis of most acromioclavicular (AC) joint pathologies depends on the knowledge of the normal range values of acromioclavicular joint space. The variation in the normal AC joint spaces among the studied population points to the need to have population-specific reference range values of acromioclavicular joint space while the paucity of data on normal acromioclavicular joint space diameter in our locality necessitated this study. Objective: This study was, therefore, aimed at radiographically determining the normal reference range values of acromioclavicular joint space diameter with age in adult Nigerian and also to find its variation with sex. Methods: This retrospective study was conducted in three tertiary hospitals in Enugu from January 2019 to July 2019. It involved digital anteroposterior shoulder radiographs of 628 adults (18 – 80 years) obtained using Zanca’s view and reported as normal by four consultant radiologists. The acromioclavicular joint space diameter is calculated as an integral of the distances between the superior and inferior borders of the acromioclavicular joint space. Data were analyzed using a linear regression model, Pearson product-moment correlation coefficient, and independent sample t-test. Results: The mean AC joint space diameter ranged from 3.63 mm at ≤ 20 years to 1.14 mm at 76-80 years of age. Acromioclavicular joint space diameter correlated strongly but negatively with age with correlation coefficients of -0.785, -.839, -.797, and -.780. There was a significant difference between the acromioclavicular joint space diameter of males and females (p = 0.000). Conclusion: This study has generated a reference range value of normal acromioclavicular joint space diameter with age in our locality while there is a difference in acromioclavicular joint space between male and female adult Nigerians.