Relationship Between Shoulder Impingement Syndrome and Thoracic Posture

Abstract

Background: Shoulder impingement syndrome (SIS) is the most common form of shoulder pain and a persistent musculoskeletal problem. Conservative and invasive treatments, aimed at the shoulder joint, have had limited success. Research suggests shoulder function is related to thoracic posture, but it is unknown whether thoracic posture is associated with SIS.

Objective: The objective of this study was to investigate whether there is a relationship between SIS and thoracic posture.

Design: This was a case control study.

Methods: Thoracic posture of 39 participants with SIS and 39 age-, gender-, and dominant arm-matched controls was measured using the modified Cobb angle from a standing lateral radiograph. Thoracic range of motion (ROM) was also measured using an inclinometer. Between-group differences were compared using t tests. The relationship between thoracic posture and thoracic ROM was determined with linear regression.

Results: Twenty women and 19 men with SIS (mean age = 57.1 years, SD = 11.1) and 39 age-matched, gender-matched, and dominant arm-matched controls (mean age = 55.7years, SD = 10.6) participated. Individuals with SIS had greater thoracic kyphosis (mean difference = 6.2o, 95% CI 2.0-10.4) and less active thoracic extension (7.8o, 95% CI = 2.2-13.4). Greater thoracic kyphosis was associated with less extension ROM (ie, more flexion when attempting full extension: β = 0.71, 95% CI = 0.45-0.97).

Limitations: These cross-sectional data can only demonstrate association and not causation. Both radiographic measurements and inclinometer measurements were not blinded.

Conclusion: Individuals with SIS had a greater thoracic kyphosis and less extension ROM than age- and gender-matched healthy controls. These results suggest that clinicians could consider addressing the thoracic spine in patients with SIS.

Keywords: Kyphosis; Posture; Radiograph; Shoulder Impingement Syndrome; Thoracic Vertebrae.