title: Surgical induced models of joint degeneration in the ovine stifle: Magnetic resonance imaging and histological assessment.
abstract: BACKGROUND
  The purposes of this study were to (1) validate and assess the reliability of a modified magnetic resonance semi-quantitative score (sheep Magnetic Resonance osteoarthritis Knee Score (sMOAKS)) to evaluate joint degeneration in the ovine knee and to (2) investigate whether the transection of the anterior cruciate ligament (ACL), isolated or in combination with meniscal injuries, reproduce the degenerative changes described in the meniscectomized sheep.
  
  
  METHODS
  Twenty sheep were randomly subjected to one of the following injuries to induce osteoarthritis (OA): ACL transection (ACLt), mid-body transection of the medial meniscus, ACLt combined with complete medial meniscectomy and complete medial meniscectomy. OA assessment was performed eight weeks postoperatively with sMOAKS, Mankin and Osteoarthritis Research Society International (OARSI) histological scores.
  
  
  RESULTS
  sMOAKS showed very good to excellent reliability (kappa=0.61 to 1.0) for the majority of features evaluated. sMOAKS revealed small differences between groups (p<0.05) being the ACLt group the most affected. We observed a strong positive correlation between the three scales in the evaluation of femoro-tibial articular cartilage (AC) (r=0.829, r=0.917, r=0.879).
  
  
  CONCLUSIONS
  sMOAKS is a reliable semi-quantitative Magnetic Resonance (MR) scale to evaluate and quantify the effect of different OA induction lesions in the ovine knee and presents a high correlation with Mankin and OARSI scales in the evaluation of femoro-tibial AC. Although minor differences were observed between the different surgical procedures for the induction of OA, ACLt proved to be the intervention that produced the highest amount of degeneration eight weeks postoperatively.
  
  
  METHODS
  II.
authors.affiliation: Orthopedic Surgery, Hospital for Special Surgery, 535 E 71st, New York 10021, NY, USA. Electronic address: jmoyaangeler@gmail.com.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Moya-Angeler
authors.affiliation: Radiology Department, Hospital Clinico San Carlos, Calle Prof Martín Lagos S/N, 28040 Madrid, Spain. Electronic address: jimenagn@gmail.com.
authors.forename: Jimena
authors.initials: J
authors.lastname: Gonzalez-Nieto
authors.affiliation: Radiology Department, Hospital Clinico San Carlos, Calle Prof Martín Lagos S/N, 28040 Madrid, Spain. Electronic address: yoki_atl@hotmail.com.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Sanchez Monforte
authors.affiliation: Surgery Department, Facultad de Veterinaria Universidad de Leon, Facultad de Veterinaria, 25, 24004 León, Spain. Electronic address: dmajrm@unileon.es.
authors.forename: Jose R
authors.initials: JR
authors.lastname: Altonaga
authors.affiliation: Orthopedic Department, Hospital Greogorio Marañon, Calle del Dr. Esquerdo, 46, 28007 Madrid, Spain. Electronic address: vaquerocot@gmail.com.
authors.forename: Javier
authors.initials: J
authors.lastname: Vaquero
authors.affiliation: School of Medicine, Universidad San Pablo CEU, Ctra. Boadilla del Monte, Km. 5 300, 28925 Alcorcon, Madrid, Spain. Electronic address: fforriol@mac.com.
authors.forename: Francisco
authors.initials: F
authors.lastname: Forriol
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008953:Models, Anatomic; D019637:Orthopedic Procedures; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000601:surgery; D015203:Reproducibility of Results; D012756:Sheep; D013264:Stifle / Q000473:pathology*
keywords: Knee; MR; Osteoarthritis; SMOAKS; Score; Sheep