title: Restriction of Postoperative Joint Loading in a Murine Model of Anterior Cruciate Ligament Reconstruction: Botulinum Toxin Paralysis and External Fixation.
abstract: Control of knee motion in small animal models is necessary to study the effect of mechanical load on the healing process. This can be especially challenging in mice, which are being increasingly used for various orthopedic reconstruction models. We explored the feasibility of botulinum toxin (Botox; Allergan, Dublin, Ireland) paralysis and a newly designed external fixator to restrict motion of the knee in mice undergoing anterior cruciate ligament (ACL) reconstruction. Nineteen C57BL/6 mice were allocated to two groups: (1) Botox group (n= 9) and (2) external fixator group (n= 10). Mice in Botox group received two different doses of Botox: 0.25 unit (n= 3) and 0.5 unit (n= 6). Injection was performed 72 hours prior to ACL reconstruction into the quadriceps, hamstring, and calf muscles of the right hind leg. Mice in external fixator group received an external fixator following ACL reconstruction. Mice were monitored for survival, tolerance, and achievement of complete knee immobilization. All mice were meant for sacrifice on day 14 postoperatively. No perceptible change in gait was observed with 0.25 unit of Botox. All mice that received 0.5 unit of Botox had complete hind limb paralysis documented by footprint analysis 2 days after injection but failed to tolerate anesthesia and were euthanized 24 hours after operation due to their critical condition. In contrast, the external fixator was well tolerated and effectively immobilized the limb. There was a single occurrence of intraoperative technical error in the external fixator group that led to euthanasia. No mechanical failure or complication was observed. Botox paralysis was not a viable option for postoperative restriction of motion and joint loading in mice. However, external fixation was an effective method for complete knee immobilization and can be used in murine models requiring postoperative control of knee loading. This study introduces a robust research tool to allow control of postoperative joint loading in animal models such as ACL reconstruction, permitting study of the effects of mechanical load on the biologic aspects of tendon-to-bone healing.
authors.affiliation: Department of Tissue Engineering, Repair, and Regeneration, Hospital for Special Surgery, New York, New York.
authors.forename: Amir
authors.initials: A
authors.lastname: Lebaschi
authors.affiliation: Department of Sports Medicine and Shoulder Surgery, Hospital for Special Surgery, New York, New York.
authors.forename: Xiang-Hua
authors.initials: XH
authors.lastname: Deng
authors.affiliation: Department of Sports Medicine, Hospital for Special Surgery, New York, New York.
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Coleman
authors.affiliation: Department of Sports Medicine, Hospital for Special Surgery, New York, New York.|Department of Orthopedic Sports Medicine, Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Camp
authors.affiliation: Department of Tissue Engineering, Repair, and Regeneration, Hospital for Special Surgery, New York, New York.
authors.forename: Jianchun
authors.initials: J
authors.lastname: Zong
authors.affiliation: Department of Tissue Engineering, Repair, and Regeneration, Hospital for Special Surgery, New York, New York.
authors.forename: Andrew
authors.initials: A
authors.lastname: Carbone
authors.affiliation: Department of Tissue Engineering, Repair, and Regeneration, Hospital for Special Surgery, New York, New York.
authors.forename: Camila B
authors.initials: CB
authors.lastname: Carballo
authors.affiliation: Department of Tissue Engineering, Repair, and Regeneration, Hospital for Special Surgery, New York, New York.
authors.forename: Guang-Ting
authors.initials: GT
authors.lastname: Cong
authors.affiliation: Department of Tissue Engineering, Repair, and Regeneration, Hospital for Special Surgery, New York, New York.
authors.forename: Zoe M
authors.initials: ZM
authors.lastname: Album
authors.affiliation: Department of Orthopaedics, Hospital for Special Surgery, New York, New York.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Rodeo
mesh_terms: D065087:Acetylcholine Release Inhibitors / Q000008:administration & dosage*; D000818:Animals; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D004195:Disease Models, Animal; D016267:External Fixators; D005260:Female; D006801:Humans; D007103:Immobilization / Q000379:methods*; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011184:Postoperative Period; D014945:Wound Healing / Q000502:physiology
chemical_list: D065087:Acetylcholine Release Inhibitors; D019274:Botulinum Toxins, Type A