Original article
Subacromial impingement syndrome: The role of posture and muscle imbalance

https://doi.org/10.1016/j.jse.2004.08.007Get rights and content

Changes in upper body posture, colloquially termed forward head posture (FHP), are considered to be an etiologic factor in the pathogenesis of subacromial impingement syndrome (SIS). The literature suggests that postural deviations associated with FHP follow distinct patterns involving an increase in the thoracic kyphosis angle and a downwardly rotated, anteriorly tilted, and protracted scapula, which in turn leads to increased compression in the subacromial space. These postural changes are thought to occur concurrently with an imbalance of the musculature, and conservative rehabilitation commonly involves addressing both posture and muscle imbalance. There is a paucity of evidence supporting the hypothesis that posture and muscle imbalance are involved in the etiology of SIS. The purpose of this study was to investigate whether FHP was associated with an increased thoracic kyphosis, an altered position of the scapula; and a reduction in glenohumeral elevation range. Selected sagittal and frontal plane postural measurements were made in 60 asymptomatic subjects and 60 subjects with SIS. The findings suggested that upper body posture does not follow the set patterns described in the literature, and further research is required to determine whether upper body and scapular posture and muscle imbalance are involved in the pathogenesis of SIS.

Section snippets

Materials and methods

Ethical approval for this study was granted by the Riverside Research Ethics Committee. Subjects were provided with information booklets explaining the purpose of the study and signed informed consent documents before participation.

Results

For this investigation, 31 asymptomatic female subjects and 29 asymptomatic male subjects were recruited. There were 2 left hand-dominant and 58 right hand-dominant individuals. The symptomatic group consisted of 25 female subjects and 35 male subjects with SIS. In this group there were 8 left hand-dominant and 52 right hand-dominant individuals. The left shoulder was painful in 25 subjects and the right in 35. The mean duration of symptoms was 1.1 years (SD, 2.5 years) with a range of 2 weeks

Discussion

The key to the clinical examination of posture is commonly described as the assessment of FHP.24 If FHP is evident, it has been proposed that the clinician may assume that the thoracic kyphosis angle will have increased and the position of the scapula will have been altered, leading to a reduction in glenohumeral range and the potential for pathology.6, 26 The results of this investigation suggest that the null hypothesis cannot be rejected, as the postural patterns described in the literature

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    Supported by the Hospital Saving Association Research Degree Award, the CSP Charitable Trust Award, and the MACP Churchill Livingstone Award for research in Manipulative Physiotherapy.

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