title: Improving bone density at the rotator cuff footprint increases supraspinatus tendon failure stress in a rat model.
abstract: The purpose of this study was to investigate whether supraspinatus tendon failure stress at the footprint can increase by improving the bone density at the rotator cuff footprint in a rat model. Bilateral ovariectomies were performed in twenty-four 4-month-old Sprague-Dawley rats. Half received bisphosphonate (zoledronic acid) and the other half received no treatment (OVX + ZOM and OVX, respectively). Twelve additional rats did not undergo ovariectomy or receive bisphosphonate treatment (CON). All rats were sacrificed at 7 months of age. Quantitative micro-computed tomography was used to assess bone density in the proximal humerus. A series of stress-relaxation tests were performed to assess stiffness and failure stress of the supraspinatus tendon. Bone density in OVX + ZOM was significantly higher at the rotator cuff footprint when compared to CON and OVX rats (p < 0.0001). The supraspinatus tendons in the OVX group were significantly stiffer when compared to the CON and OVX + ZOM groups (p < 0.05). The failure stress of the OVX + ZOM group was significantly greater than the CON and OVX groups (22.89 +/- 4.43 MPa vs. 18.36 +/- 3.16 and 17.70 +/- 4.92, respectively). In conclusion, improving the bone density at the rotator cuff footprint enhances failure stress of the suprapinatus tendon.
authors.affiliation: Center of Shoulder, Elbow, and Sports Medicine, Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th Street, PH 11th Floor, New York, New York 10032, USA. ec2195@columbia.edu
authors.forename: Edwin R
authors.initials: ER
authors.lastname: Cadet
authors.forename: George C
authors.initials: GC
authors.lastname: Vorys
authors.forename: Ra'Kerry
authors.initials: R
authors.lastname: Rahman
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Gardner
authors.forename: Francis Y
authors.initials: FY
authors.lastname: Lee
authors.forename: William N
authors.initials: WN
authors.lastname: Levine
authors.forename: Louis U
authors.initials: LU
authors.lastname: Bigliani
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ahmad
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D004164:Diphosphonates / Q000494:pharmacology; D005260:Female; D006811:Humerus / Q000000981:diagnostic imaging / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D009929:Organ Size; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D017006:Rotator Cuff; D013314:Stress, Mechanical; D013710:Tendons / Q000473:pathology / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014599:Uterus / Q000473:pathology; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid