In vivo analysis of coracoid and subacromial shoulder impingement mechanism during clinical examination.
Level 3 - non-randomized controlled study
Non-randomized comparative imaging study with within-subject repeated measures
PubMed 28188359 · doi:10.1007/s00590-017-1919-7
What was done
Researchers evaluated subacromial and coracoid impingement mechanisms during shoulder clinical examination maneuvers using a 1.0-T open MRI system in 37 subjects (18 female, 19 male). Distances between the humeral head and the acromion or coracoid, along with rotator cuff contact grades, were measured in four positions: neutral, Hawkins, Neer, and 90° abduction with 15° internal rotation (horizontal impingement test).
What was found
In the Hawkins position, the distance between the supraspinatus and coracoid was closest (14.5 ± 4.5 mm), and the coracohumeral distance (CHD) narrowed significantly (p < 0.001). In the horizontal impingement position, the minimum distance between the subscapularis and coracoid was observed, while CHD increased to 27.4 ± 5.7 mm. Compared to the neutral position, the space between the greater tuberosity and acromion was significantly narrowed in the Neer, Hawkins, and horizontal impingement positions (p < 0.001), producing comparable subacromial rotator cuff contact across all three tests.
Why it matters
This study provides in vivo imaging evidence that Hawkins, Neer, and horizontal impingement maneuvers all reproduce subacromial narrowing, while forward flexion with internal rotation (Hawkins) and abduction with internal rotation (horizontal impingement) provoke distinct coracoid impingement pathways.
Limits
The abstract does not state whether participants were symptomatic patients or healthy volunteers. The sample size is modest (n = 37), and static positioning inside an open MRI may not fully capture dynamic muscle activation and joint kinematics during active clinical examination.
Cited by
- supports Raising the arm in an internally rotated posture causes the greater tubercle of the humerus to impinge on the upper shoulder joint structures.