[Acromial osteophyte in shoulder impingement syndrome. Diagnosis and prevalence]

The shoulder impingement syndrome (SIS) is caused by the compression of the rotator cuff tendon tear and the subacromial bursa between the humeral head and the structures that conforms the subacromial arc.

To determine a proportion of the acromial spur in the SIS comparing it with the general population. A second one would be to evaluate the quality of the radiological technique.

A comparative cross-sectional study was made in 148 patients, divided in two groups: one conformed by 52 persons, for patients with SIS and the other, conformed by 96, for the general population of similar age. The technique used to detect the acromial spur was the anteroposterior shoulder plate with a ray at 30 degrees in caudal direction in a bilateral way that was blindly interpreted by an orthopedist in two occasions, obtaining a high concordance index of Kappa of 0.90. The criteria to consider positive spur was that the bone growth could exceed a prolongation of an imaginary line at the inferior edge of the clavicle.

The average age in both groups was of 48.7 years +/- 14.5 years for the patients with SIS, and of 43.2 years +/- 12.9 for the patients of the control group. It was founded that 84.6% of the patients with SIS had acromial spur and in the ones of the control group, it was founded in a 36%, being this difference significant with OR of 9.3 times more frequent to have spur in patients with SIS. The quality of the technique was good in 92% of the Rx.

The frequency of spur in SIS is high (84.6%), but it calls our attention that the frequency in general population was moderate (36%).