title: Anatomical study: comparing the human, sheep and pig knee meniscus.
abstract: BACKGROUND
  Animal models are commonly used in investigating new treatment options for knee joint injuries including injuries to the meniscus. The reliability and applicability of these models to replicate findings in humans depends on determining the most suitable animal proxy. Therefore, this study was designed to compare the wet weight, volume and dimensions of the human meniscus with two commonly used animal models: sheep and pig.
  
  
  METHODS
  Human menisci (n = 6 pairs) were obtained from the knee joints of cadaveric male donors. Sheep menisci (n = 6 pairs) and pig menisci (n = 22 pairs) were obtained from the stifle joints of adult sheep and pigs. Meniscal wet weight, volume and dimensions of the body were measured and compared among the species. Anatomical dimensions included circumference, width, peripheral height, articular height and superior articular length.
  
  
  RESULTS
  The circumference of human menisci (lateral: 84.0 mm, medial: 88.7 mm) was significantly longer than that of sheep (lateral: 50.0 mm, medial: 55.5 mm) and pig (lateral: 66.8 mm, medial: 64.9 mm). The majority of the remaining dimensions of the medial and all of the remaining dimensions of the lateral menisci in sheep showed no statistical difference in comparison to the human menisci. The meniscal weight in pig was significantly larger (lateral: 6.4 g, medial: 5.0 g) than the human (lateral: 4.9 g, medial: 4.4 g) and sheep (lateral: 2.5 g, medial: 2.2 g). Porcine meniscal volume (lateral: 6.5 ml, medial: 5.1 ml) was also larger than the human (lateral: 5.0 ml, medial: 4.5 ml) and sheep (lateral: 2.3 ml, medial: 2.2 ml) menisci. The dimensions measured in the pig meniscus were generally larger than human menisci with statistically significant differences in most categories.
  
  
  CONCLUSIONS
  Sheep meniscal dimensions more closely matched human meniscal dimensions than the pig meniscal dimensions. This information may help guide the choice of an animal proxy in meniscal research.
authors.affiliation: Department of Surgery, Laboratory of Orthopaedic Research, University of Alberta, Edmonton, Canada. takroni@ualberta.ca.|Rabigh Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia. takroni@ualberta.ca.
authors.forename: Talal
authors.initials: T
authors.lastname: Takroni
authors.affiliation: Department of Surgery, Laboratory of Orthopaedic Research, University of Alberta, Edmonton, Canada.
authors.forename: Leila
authors.initials: L
authors.lastname: Laouar
authors.affiliation: Department of Surgery, Laboratory of Stem Cell Biology and Orthopaedic Tissue Engineering, University of Alberta, Edmonton, Canada.
authors.forename: Adetola
authors.initials: A
authors.lastname: Adesida
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada.|Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Canada.
authors.forename: Janet A W
authors.initials: JA
authors.lastname: Elliott
authors.affiliation: Department of Surgery, Laboratory of Orthopaedic Research, University of Alberta, Edmonton, Canada.
authors.forename: Nadr M
authors.initials: NM
authors.lastname: Jomha