title: Immediate ACL reconstruction prevents microvascular pathophysiology in the uninjured MCL that is not fully reversed by delayed ACL reconstruction.
abstract: Anterior cruciate ligament (ACL) injury induces maladaptive vascular responses that degrade medial collateral ligament (MCL) function. The purpose of this study was to determine if early or delayed ACL reconstruction can prevent or reverse the abnormal changes in vascular function that occur in the uninjured MCL after ACL injury. Twenty-four rabbits were divided into four groups (n = 6); control, ACL-deficient (ACL-X), immediate ACL reconstructed (ACL-IR) and delayed ACL reconstructed (ACL-DR). After 8 weeks, MCLs were assessed for blood flow, responses to acetylcholine (ACh) and phenylephrine (Phe) and autoregulatory responses, using laser speckle perfusion imaging. In ACL-X knees, blood flow in the MCL increased by 2.5-fold compared to control. MCL hyperemia was diminished in ACL-DR knees and was unaltered in ACL-IR knees. MCL vasculature was unresponsive to ACh and Phe in ACL-X. These responses were partially restored by ACL reconstruction. Autoregulatory responses were not significantly different between groups. ACL-DR decreased hyperemia in the MCL and partially attenuated abnormal MCL vascular responses. ACL-IR was more effective at preventing MCL hyperemia and preserving vascular responsiveness to ACh and Phe. This suggests that the vascular alterations in the uninjured rabbit MCL are largely caused by abnormal mechanical loading resulting from ACL deficiency and can be prevented through early reconstruction. Early ACL reconstruction could limit the progression of microvascular dysfunction of the MCL, and preserve physiological joint homeostasis. This might prevent joint degeneration and delay the progression of osteoarthritis.
authors: Department of Surgery, University of Calgary, Calgary, Alberta, Canada.
authors: Takeo
authors: T
authors: Mammoto
authors: Ross
authors: R
authors: Demcoe
authors: Daniel
authors: D
authors: Miller
authors: Catherine
authors: C
authors: Leonard
authors: Ruth
authors: R
authors: Seerattan
authors: Robert
authors: R
authors: Bray
authors: Paul
authors: P
authors: Salo
mesh_terms: D000109:Acetylcholine; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D004195:Disease Models, Animal; D005260:Female; D017888:Medial Collateral Ligament, Knee / Q000098:blood supply / Q000503:physiopathology*; D055806:Microvessels / Q000187:drug effects / Q000503:physiopathology*; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D010656:Phenylephrine; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013264:Stifle / Q000098:blood supply / Q000503:physiopathology* / Q000601:surgery; D013997:Time Factors; D014945:Wound Healing
chemical_list: D010656:Phenylephrine; D000109:Acetylcholine