title: Effect of overuse-induced tendinopathy on tendon healing in a rat supraspinatus repair model.
abstract: Supraspinatus tears often result in the setting of chronic tendinopathy. However, the typical repair model utilizes an acute injury. In recognition of that distinction, our laboratory developed an overuse animal model; however it is unclear whether induced overuse is necessary in the repair model. We studied the repair properties of overuse-induced tendons compared to normal tendons. We hypothesized that histological and mechanical properties would not be altered between the overuse-induced and normal tendons 1 and 4 weeks after repair. Thirty-one adult male Sprague-Dawley rats were subjected to either overuse or cage activity for 4 weeks prior to bilateral supraspinatus tendon repair surgery. Rats were sacrificed at 1 and 4 weeks post-surgery and evaluated for histology and mechanics. Results at 1 week showed no clear histologic changes, but increased inflammatory protein expression in overuse tendons. At 4 weeks, percent relaxation was slightly increased in the overuse group. No other alterations in mechanics or histology were observed. Our results suggest that the effects of the surgical injury overshadow the changes evoked by overuse. Because clinically relevant mechanical parameters were not altered in the overuse group, we conclude that when examining tendons 4 weeks after repair in the classic rat supraspinatus model, inducing overuse prior to surgery is likely to be unnecessary.
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.
authors.forename: Jennica J
authors.initials: JJ
authors.lastname: Tucker
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.
authors.forename: Corinne N
authors.initials: CN
authors.lastname: Riggin
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.
authors.forename: Brianne K
authors.initials: BK
authors.lastname: Connizzo
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.|Philadelphia VA Medical Center (PVAMC), Philadelphia, Pennsylvania.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Mauck
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.|Philadelphia VA Medical Center (PVAMC), Philadelphia, Pennsylvania.
authors.forename: David R
authors.initials: DR
authors.lastname: Steinberg
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.|Philadelphia VA Medical Center (PVAMC), Philadelphia, Pennsylvania.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Kuntz
authors.affiliation: McKay Orthopaedic Research Laboratory, Philadelphia, Pennsylvania.
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Soslowsky
authors.affiliation: Philadelphia VA Medical Center (PVAMC), Philadelphia, Pennsylvania.
authors.forename: Joseph
authors.initials: J
authors.lastname: Bernstein
mesh_terms: D000818:Animals; D012090:Cumulative Trauma Disorders / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D053583:Interleukin-1beta / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008297:Male; D017207:Rats, Sprague-Dawley; D017006:Rotator Cuff / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D000070636:Rotator Cuff Injuries; D052256:Tendinopathy / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D013708:Tendon Injuries / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D017493:Leukocyte Common Antigens; C516771:Ptprc protein, rat
keywords: animal model; overuse; supraspinatus tendon repair