title: Osteoarthritic changes of the patellofemoral joint in STR/OrtCrlj mice are the earliest detectable changes and may be caused by internal tibial torsion.
abstract: STR/ort mice develop a naturally occurring osteoarthritis (OA) of the knee joints. However, the evaluation of early OA changes has been difficult due to variability caused by gender, individual differences, and differences between the right and left lower limbs. The objective of this study was to analyze the variability of the early OA changes with age in STR/ort mice and to identify the cause of onset. A total of 115 STR/OrtCrlj mice aged 10-45 weeks were examined. In addition to conventional radiological and histological evaluation of the knee joints, histological sections were used to examine the patellofemoral, femorotibial, and growth plate cartilage under similar conditions. A morphological evaluation of tibiae, including micro-3-dimensional computed tomography, was performed. Radiological evaluation showed OA changes in the joints of mice over 35 weeks old and histological evaluation showed early OA changes in the femorotibial joints of mice over 26 weeks old. However, these changes were not common in all individuals. In contrast, most common and reproducible OA changes were observed in the bilateral patellofemoral joints of all individuals, and even in subjects ranging from 10 to 20 weeks of age. Morphological evaluations also demonstrated an abnormal tibial internal torsion that increased with age and was associated with medial patellar dislocation. In conclusion, the earliest histological OA change was observed in the patellofemoral joint prior to similar observations in the femorotibial joint. Internal tibial torsion may be a cause of OA in the patellofemoral joints, which leads to the development of medial femorotibial OA.
authors.affiliation: Department of Orthopaedic Surgery, Kitasasto University School of Medicine, Kanagawa, Japan. knaruse@med.kitasato-u.ac.jp
authors.forename: Kouji
authors.initials: K
authors.lastname: Naruse
authors.forename: Ken
authors.initials: K
authors.lastname: Urabe
authors.forename: Shi-Xu
authors.initials: SX
authors.lastname: Jiang
authors.forename: Kentaroo
authors.initials: K
authors.lastname: Uchida
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kozai
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Minehara
authors.forename: Yuko
authors.initials: Y
authors.lastname: Mikuni-Takagaki
authors.forename: Isamu
authors.initials: I
authors.lastname: Kashima
authors.forename: Moritoshi
authors.initials: M
authors.lastname: Itoman
mesh_terms: D000367:Age Factors; D000818:Animals; D001169:Arthritis, Experimental / Q000000981:diagnostic imaging / Q000473:pathology*; D004195:Disease Models, Animal; D007719:Knee Joint / Q000166:cytology*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology*; D014102:Torsion Abnormality / Q000473:pathology*