Relative Ratio of Coracohumeral Distance is Greater in Patients with Subcoracoid Impingement (SCI)

Abstract

Purpose: No standard imaging diagnostic criteria have yet been established for subcoracoid
impingement (SCI) of the shoulder. The purpose of this study was to evaluate coracohumeral
distance (CHD) in patients with or without SCI with the hypothesis that patients with SCI
would have narrower CHD.
Materials and Methods: One hundred fifty patients with subacromial impingement (SAI) were
evaluated. The subjects with subcoracoid impingement which was affirmed clinically and confirmed
by ultrasound guided subcoracoid injection (n=39) was compared with patients with
SAI only (n=111). Patients with stiffness and rotator cuff tear were excluded. Absolute CHD
was measured on magnetic resonance imaging (MRI) axial images and on ultrasound with
the humerus in neutral position and internal rotation. Also relative ratio of distance difference
(RRDD) defined as the difference of CHD in neutral position and internal rotation compared
with absolute CHD in neutral on ultrasound was also measured.
Results: The distance measured in neutral position was similar between ultrasound (US) imaging
and MRI (p>0.05) and both measurements did not have significant difference between the
two groups (p>0.05). On ultrasound, there was no significant difference in CHD in neutral and
the internal rotation position between the two groups. However, RRDD value was significantly
greater in SCI group (p<0.05).
Conclusion: Although, the SCI group and the SAI group were not matched for age, sex, or
BMI, no significant difference in CHD was seen between the SCI and SAI groups. RRDD value
was greater in SCI group suggesting that individualized CHD in internal rotation should be
taken into account when assessing patients with subcoracoid impingement.