Authors: Jaclyn N ChoppHurley John M O’Neill Clark R Dickerson
Publish Date: 2015/08/09
Volume: 38, Issue: 1, Pages: 135-146
Abstract
Particular bone and tissue morphological features of the scapula and humerus often exist disproportionately in persons with subacromial impingement syndrome SAIS and/or rotator cuff pathology However the origins of morphological variation genetic or mechanistic remain unclear This research evaluated the distribution of and correlation between several bone and tissue characteristics associated with these pathologies amongst a baseline cohort population consisting of young healthy males As well the predisposition to SAIS was estimated by calculating the ratio occupation ratio of subacromial tissue thickness to minimum subacromial space width SASAnteriorposterior and transscapular radiographs and musculoskeletal ultrasound were used to measure morphological characteristics related to the subacromial space Each bone morphological characteristic was classified as healthy or unhealthy based on previous definitions Supraspinatus tendon and subacromial bursa thicknesses were used to calculate the occupation ratio from both radiographic and ultrasonic measures of the SASEach characteristic demonstrated considerable variability with some participants having ‘unhealthy’ variants for each bone characteristic examined The percentage of the population with bone characteristics classified as “unhealthy” ranged from 15 to 55 across characteristics evaluated The strongest correlation existed between the acromion index and the minimum subacromial space width −059 suggesting that a larger lateral extension of the acromion may predispose an individual to SAIS The average occupation ratio was 653 with a 1–99 confidence interval ranging from 216 to 1089 The distributions of both morphological characteristics and occupation ratios indicate that individuals within this healthy baseline population have a highly differential predisposition for subacromial tissue compression solely based on inherent morphological variation This suggests that while mechanistic and/or agerelated degenerative changes may contribute to SAIS and eventual rotator cuff pathology intrinsic predisposing geometry should not be discountedPartial project support came from a CIHR Research Incentive Fund Grant from the University of Waterloo on which Dr Clark Dickerson was the principle investigator Jaclyn ChoppHurley was supported through an NSERC PGSD award Many thanks to Alison McDonald Jacquelyn Maciukiewicz and the team of ultrasound and radiographic technologists and research coordination staff at St Joseph’s Healthcare Hamilton for all of their assistance during data collection
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