title: Comparison of microstructural and mechanical properties of trabeculae in femoral head from osteoporosis patients with and without cartilage lesions: a case-control study.
abstract: BACKGROUND
  Degeneration of cartilage will change load distribution, affecting bone remodeling progress and trabecular structure and strength. However, in human primary osteoporosis, whether cartilage lesions would also affect properties beneath trabecular bone remains unknown. In this study, we explored the differences in local trabecular properties between osteoporosis patients with and without cartilage lesions.
  
  
  METHODS
  Eighteen pairs of femoral heads with and without cartilage lesions in a weight-bearing area were collected from senile femoral neck fracture patients. The Mankin score and glycosaminoglycan (GAG) content were used to evaluate the severity of the cartilage lesions. Micro-CT and compression tests were used to obtain structural and mechanical characteristics of each trabecular column. Multivariate linear regression was performed to evaluate the association between mechanical parameters and the degree of cartilage lesion.
  
  
  RESULTS
  In osteoporosis patients with cartilage lesions, the bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) of the trabecular column were significantly higher than that of osteoporotic control patients (all P < 0.05), while the Young's modulus was lower (P = 0.024). Multivariable linear regression indicated that in both groups, bone mineral density (BMD) significantly correlated with Young's modulus (all P < 0.05). While in patients with cartilage lesion, GAG content was also correlated with Young's modulus (standardized coefficient 0.443, P < 0.01).
  
  
  CONCLUSIONS
  Osteoporosis patients with cartilage lesions exhibited a weaker mechanical property of trabeculae. The intimate association of cartilage lesions and impairment of trabecular mechanical properties indicate that cartilage and trabeculae belong to an interdependent functional unit. Previously proposed adaptive mechanisms in osteoarthritis might also be applicable to the progression of osteoporosis.
authors.affiliation: Department of Orthopedics, General Hospital of Chinese PLA, No.28 Fuxing Road, Beijing, China. houchenlv@163.com.
authors.forename: Houchen
authors.initials: H
authors.lastname: Lv
authors.affiliation: Department of Orthopedics, General Hospital of Chinese PLA, No.28 Fuxing Road, Beijing, China. zhanglcheng218@126.com.
authors.forename: Licheng
authors.initials: L
authors.lastname: Zhang
authors.affiliation: BNLMS State Key Laboratory of Polymer Physics & Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China. feiyang@iccas.ac.cn.
authors.forename: Fei
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Orthopedics, General Hospital of Chinese PLA, No.28 Fuxing Road, Beijing, China. zhaozhao_02@163.com.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Department of Orthopedics, Beijing Shijitan Hospital, Beijing, China. yqjh2010@163.com.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yao
authors.affiliation: Department of Orthopedics, General Hospital of Chinese PLA, No.28 Fuxing Road, Beijing, China. zhanglihai301@gmail.com.
authors.forename: Lihai
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, General Hospital of Chinese PLA, No.28 Fuxing Road, Beijing, China. pftang301@126.com.
authors.forename: Peifu
authors.initials: P
authors.lastname: Tang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology; D016723:Bone Remodeling / Q000502:physiology; D002357:Cartilage Diseases / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D055119:Elastic Modulus; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology* / Q000648:ultrastructure*; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D010024:Osteoporosis / Q000473:pathology* / Q000503:physiopathology; D011859:Radiography; D012720:Severity of Illness Index; D015898:Tomography Scanners, X-Ray Computed