title: Subchondral and epiphyseal bone remodeling following surgical transection and noninvasive rupture of the anterior cruciate ligament as models of post-traumatic osteoarthritis.
abstract: OBJECTIVE
  Animal models are frequently used to study post-traumatic osteoarthritis (PTOA). A common anterior cruciate ligament (ACL) injury model is surgical transection, which may introduce confounding factors from surgery. Noninvasive models could model human injury more closely. The purpose of this study was to compare subchondral and epiphyseal trabecular bone remodeling after surgical transection and noninvasive rupture of the ACL.
  
  
  METHODS
  Thirty-six rats were randomized to an uninjured control, surgical transection (Transection), or noninvasive rupture (Rupture). Animals were randomized to 4 or 10 week time points (n = 6 per group). Micro computed tomography (μCT) imaging was performed with an isotropic voxel size of 12 μm. Subchondral and epiphyseal bone was segmented semi-automatically, and morphometric analysis was performed.
  
  
  RESULTS
  Transection caused a greater decrease in subchondral bone volume fraction (BV/TV) than Rupture in the femur and tibia. Rupture had greater subchondral bone tissue mineral density (TMD) at 4 and 10 weeks in the femur and tibia. Subchondral bone thickness (SCB.Th) was decreased in the femur in Transection only. Epiphyseal BV/TV was decreased in Transection only, and Rupture exhibited increased femoral epiphyseal TMD compared to both Control and Transection. Rupture exhibited greater femoral epiphyseal trabecular thickness (Tb.Th.) compared to Control and Transection at 4 weeks, and both Rupture and Transection had increased femoral epiphyseal Tb.Th. at 10 weeks. Epiphyseal trabecular number (Tb.N) was decreased in both injury groups at both time points. Femoral and tibial epiphyseal structure model index (SMI) increased in both groups.
  
  
  CONCLUSIONS
  The two injury models cause differences in post-injury bone morphometry, and surgical transection may be introducing confounding factors that affect downstream bony remodeling.
authors.affiliation: Orthopaedic Research Laboratory, Beaumont Health System, Royal Oak, MI, United States; Department of Orthopaedic Surgery, Oakland University - William Beaumont School of Medicine, Rochester, MI, United States; Department of Biomedical Engineering, Wayne State University, Detroit, MI, United States.
authors.forename: T
authors.initials: T
authors.lastname: Maerz
authors.affiliation: Orthopaedic Research Laboratory, Beaumont Health System, Royal Oak, MI, United States; Department of Orthopaedic Surgery, Oakland University - William Beaumont School of Medicine, Rochester, MI, United States.
authors.forename: M
authors.initials: M
authors.lastname: Kurdziel
authors.affiliation: Orthopaedic Research Laboratory, Beaumont Health System, Royal Oak, MI, United States.
authors.forename: M D
authors.initials: MD
authors.lastname: Newton
authors.affiliation: Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, United States.
authors.forename: P
authors.initials: P
authors.lastname: Altman
authors.affiliation: Department of Orthopaedic Surgery, Oakland University - William Beaumont School of Medicine, Rochester, MI, United States; Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, United States.
authors.forename: K
authors.initials: K
authors.lastname: Anderson
authors.affiliation: Department of Biomedical Engineering, Wayne State University, Detroit, MI, United States; Department of Chemical Engineering & Materials Science, Wayne State University, Detroit, MI, United States.
authors.forename: H W T
authors.initials: HW
authors.lastname: Matthew
authors.affiliation: Orthopaedic Research Laboratory, Beaumont Health System, Royal Oak, MI, United States; Department of Orthopaedic Surgery, Oakland University - William Beaumont School of Medicine, Rochester, MI, United States. Electronic address: kevin.baker@beaumont.edu.
authors.forename: K C
authors.initials: KC
authors.lastname: Baker
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D001169:Arthritis, Experimental / Q000209:etiology*; D015519:Bone Density / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology*; D015986:Confounding Factors, Epidemiologic; D004838:Epiphyses / Q000503:physiopathology; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D010003:Osteoarthritis / Q000209:etiology*; D011897:Random Allocation; D011917:Rats, Inbred Lew; D012421:Rupture / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology; D055114:X-Ray Microtomography / Q000379:methods
keywords: Anterior cruciate ligament rupture; Bone morphometry; Epiphyseal bone remodeling; Post-traumatic osteoarthritis; Subchondral bone remodeling; μCT