Acromial spur: relationship to aging and morphologic changes in the rotator cuff.

This study's objective is to elucidate the relationship between acromial spur formation and rotator cuff pathology or aging. The subjects comprised 1029 shoulders in control, cadaveric, and operative groups. A radiograph in the supraspinatus outlet view was taken in all subjects. The lengths of the incident spurs were measured and classified into 3 sizes (small, <5 mm; medium, <10 mm; and large, > or =10 mm). The rotator cuff was macroscopically classified as normal or as having bursal-side fraying, joint-side tear, intratendinous tear, bursal-side tear, complete tear limited to the supraspinatus tendon, or massive tear. In the control group, the overall incidence of spurs and spur size increased with advancing age (P < .001), but the majority of spurs were small (<5 mm). In the cadaveric group, the overall incidence did not correlate with advancing age (P > .05). However, spur size increased with age in subjects aged 50 years or older (P < .001). The incidence of spurs in rotator cuffs with bursal-side tears was highest and was significantly higher than that in normal cuffs and cuffs with bursal-side fraying and intratendinous tears. We observed 40% of medium spurs and 69% of large spurs in cases with bursal-side tears, complete tears limited to the supraspinatus tendon, and massive tears. In the operative group, the overall incidence correlated to advancing age (P < .001), reaching 80% or more in subjects aged 30 years or older. In addition, the size of spurs was larger than that in the other 2 groups in all age groups with few exceptions (P < .05). Small spurs were associated with advancing age. Morphologic change to the bursal side of the rotator cuff may enhance spur growth. The presence of a small spur has no diagnostic value for rotator cuff tears. Spurs measuring 5 mm or more, however, are of diagnostic value because of their high rate of association with bursal-side tear, complete tears limited to the supraspinatus tendon, or massive tears.