Rotator Cuff Muscular Edema in Human: A Clinical and Radiological Analysis From the LaTour Group.

BACKGROUND

Early formation of muscle edema after rotator cuff injury has previously been demonstrated in an animal model.

PURPOSE

To describe the same phenomenon in humans through analysis of rotator cuff muscle edema on magnetic resonance imaging/arthrography (MRI/MRA).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Demographic, clinical, and radiological characteristics of patients with both a history of trauma and clear muscle edema of the rotator cuff were analyzed. Two groups were established based on the degree of concomitant fatty infiltration: (1) an acute group with little to no fatty infiltration of the rotator cuff muscle, and (2) an acute-on-chronic group with significant presence of fatty infiltration.

RESULTS

Of the 71 shoulders, 45 (63.4%) were identified as acute lesions and 26 (36.6%) as acute-on-chronic lesions. Patients in the acute group were younger (60 ± 11 years [range, 38-83 years] vs 68 ± 11 years [range, 52-90 years]; = .006) and received earlier MRIs compared with patients in the acute-on-chronic group (23 ± 21 [range, 0-87) vs 42 ± 40 [range, 4-179]; = .019). No other radiological characteristics studied-such as edema location, lesion type, tendon retraction, and other radiological signs-were able to distinguish the groups.

CONCLUSION

Muscle edema of retraction helps to distinguish new traumatic rotator cuff injury from acute extensions of preexisting lesions via fatty infiltration and age at presentation. The difference in time between symptom onset and MRI/MRA is also a discriminating factor.