title: Effects of methylprednisolone and betamethasone injections on the rotator cuff: an experimental study in rats.
abstract: Thirty-one female Sprague-Dawley rats were used to determine the effects of subacromial corticosteroid injections on the rotator cuff. The injection technique was tested in 6 animals, which were excluded from the study. The remaining 25 rats were randomly divided into three groups of 8 animals each; a single rat received no injections. Every other week for 8 weeks, one shoulder in each rat was injected with methylprednisolone, betamethasone, or saline in a dosage equivalent to that used in humans. The supraspinatus and infraspinatus tendons were removed 10 days after the last injection and evaluated. There were no pathologic changes in the tendons injected with saline. In 43% of the methylprednisolone-treated rats and 29% of the betamethasone-treated rats, the tendons were abnormally soft and light-colored. In 43% of the methylprednisolone group and 71% of the betamethasone group, fragmentation of collagen bundles and inflammatory cell infiltration were evident. Subacromial injections of methylprednisolone or betamethasone repeated frequently can cause deleterious changes in the normal structure of the rat rotator cuff. In light of these findings, therapy for subacromial impingement syndrome of the shoulder with frequent, repeated steroid injections is potentially harmful.
authors.affiliation: Baskent University Medical Center, Department of Orthopedics and Traumatology, Adana, Turkey.
authors.forename: Sercan
authors.initials: S
authors.lastname: Akpinar
authors.forename: Murat A
authors.initials: MA
authors.lastname: Hersekli
authors.forename: Huseyin
authors.initials: H
authors.lastname: Demirors
authors.forename: Reha N
authors.initials: RN
authors.lastname: Tandogan
authors.forename: Fazilet
authors.initials: F
authors.lastname: Kayaselcuk
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001623:Betamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D007270:Injections, Intra-Articular; D008775:Methylprednisolone / Q000494:pharmacology*; D011336:Probability; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D017006:Rotator Cuff / Q000187:drug effects* / Q000473:pathology*; D019534:Shoulder Impingement Syndrome / Q000188:drug therapy; D012785:Shoulder Joint / Q000187:drug effects / Q000503:physiopathology; D016896:Treatment Outcome
chemical_list: D001623:Betamethasone; D008775:Methylprednisolone