title: Botulinum toxin is detrimental to repair of a chronic rotator cuff tear in a rabbit model.
abstract: Re-tear continues to be a problem after rotator cuff repair. Intramuscular botulinum toxin (Botox) injection can help optimize tension at the repair site to promote healing but could have an adverse effect on the degenerated muscle in a chronic tear. We hypothesized that Botox injection would improve repair characteristics without adverse effect on the muscle in a chronic rotator cuff tear model. The supraspinatus tendon of both shoulders in 14 rabbits underwent delayed repair 12 weeks after transection. One shoulder was treated with intramuscular Botox injection and the other with a saline control injection. Six weeks after repair, outcomes were based on biomechanics, histology, and magnetic resonance imaging. Botox-treated repairs were significantly weaker (2.64 N) than control repairs (5.51 N, p = 0.03). Eighty percent of Botox-treated repairs and 40% of control repairs healed with some partial defect. Fatty infiltration of the supraspinatus was present in all shoulders (Goutallier Grade 3 or 4) but was increased in the setting of Botox. This study provides additional support for the rabbit supraspinatus model of chronic cuff tear, showing consistent fatty infiltration. Contrary to our hypothesis, Botox had a negative effect on repair strength and might increase fatty infiltration.
authors: Department of Orthopaedics, University of Maryland, Maryland, Baltimore.
authors: Mohit
authors: M
authors: Gilotra
authors: Department of Orthopaedics, University of Maryland, Maryland, Baltimore.
authors: Thao
authors: T
authors: Nguyen
authors: Department of Orthopaedics, University of Maryland, Maryland, Baltimore.
authors: Matthew
authors: M
authors: Christian
authors: Department of Orthopaedics, University of Maryland, Maryland, Baltimore.
authors: Derik
authors: D
authors: Davis
authors: Department of Orthopaedics, University of Maryland, Maryland, Baltimore.
authors: R Frank
authors: RF
authors: Henn
authors: Department of Orthopaedics, University of Maryland, Maryland, Baltimore.
authors: Syed Ashfaq
authors: SA
authors: Hasan
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001905:Botulinum Toxins / Q000633:toxicity*; D002908:Chronic Disease; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging; D011817:Rabbits; D017006:Rotator Cuff / Q000473:pathology; D000070636:Rotator Cuff Injuries; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D001905:Botulinum Toxins
keywords: botulinum toxin; chronic rotator cuff tear; fatty infiltration; rabbit model; rotator cuff repair