Oedème musculaire de rétraction et pseudo-infiltration graisseuse après lésion traumatique de la coiffe des rotateurs

Introduction This study aimed to describe the characteristics of edema associated with a retracted rotator cuff tear and to highlight the risk of a potential pseudo fatty infiltration of the cuff muscle. Materiel et methode Two studies were performed. An initial basic science animal study on sheep was performed to confirm the existence of muscle edema associated with a retracted rotator cuff tendon tear and pseudo fatty infiltration. Surgical tenotomy of the infraspinatus of the right shoulder was performed on 14 sheep. Magnetic Resonance Imaging (MRI) scans were performed immediately after surgery and at 2- and 4-weeks post-surgery. T1 weighted with fat saturation, T2 weighted and DIXON pure fat sequences were reviewed for hyper-intense signals. Thereafter, a retrospective study of a patient cohort with traumatic, retracted rotator cuff tears associated with muscle edema was performed. MRI scans were assessed for characteristic muscle edema patterns. Resultats The animal study showed that edema mimics pseudo fatty infiltration. The edema of retraction creates a characteristic muscle ground glass appearance on T1 weighted sequences and is often found in either peri or intra-muscular location of the rotator cuff muscle. The human cohort consisted of 60 patients (47 men and 13 women) with a mean age of 65 years (± 11). The average time of injury to MRI was 36 days (range, 0 to 149 days). Fifty-one patients (85%) had supraspinatus retraction whilst 32 patients had infraspinatus retraction (53%). Supraspinatus edema was observed in 48 patients (80%). Twenty-nine patients (60%) had peripheral edema, 11 patients (23%) had muscle body edema, 5 patients (10%) had musculotendinous edema and 3 patients (6%) had global supraspinatus edema. Hypersignal in both T1, T2 weighted with fat saturation sequences was noticed in 52 patients (87%). Conclusions Edema of retraction can appear hours following a traumatic rotator cuff tear. The location of this edema is often peripheral or intra-muscular. Edema of retraction presents as a characteristic muscle ground glass appearance in T1 weighted sequences.