title: Subchondral bone turnover, but not bone volume, is increased in early stage osteoarthritic lesions in the human hip joint.
abstract: OBJECTIVE
  The pathogenesis of osteoarthritis (OA) is not fully understood, but bone changes are suggested to be important. Bone turnover and bone volume (BV) in human hip OA were investigated in relation to the overlying cartilage degeneration using design-based stereological estimators.
  
  
  METHODS
  Femoral heads were obtained from 25 end-stage OA patients and 24 controls (CTL). Design-based stereological methods were used for sampling and quantification to obtain absolute estimates of volume and surface in the central trabecular and the subarticular bone region. The subarticular bone was further subdivided into regions according to the OARSI-score of the overlying articular cartilage in which erosion and osteoid surfaces were estimated.
  
  
  RESULTS
  In the subarticular region, bone volume (BV/TV) was 15.0% higher in OA patients compared to CTL; The fraction of erosive (ES/BS) and osteoid surfaces (OS/BS) were 56.2% and 72.8% higher in OA compared to CTL. In subarticular regions with none to mild cartilage degeneration (OARSI grade 0-2), ES/BS and OS/BS were 48.6% and 59.9% higher in OA compared to CTL, whereas BV/TV did not differ between OA and CTL.
  
  
  CONCLUSIONS
  In human end-stage hip OA, BV and bone turnover correlate with the degree of local cartilage degeneration. Subarticular bone sclerosis was only present in regions corresponding to end-stage OA. However, in regions with only none to mild cartilage degeneration the underlying bone had significantly higher turnover in OA patients compared to the control group, suggesting that high bone turnover may contribute to the early pathogenesis of OA.
authors.affiliation: Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: R
authors.initials: R
authors.lastname: Klose-Jensen
authors.affiliation: Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: L B
authors.initials: LB
authors.lastname: Hartlev
authors.affiliation: Institute of Forensic Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: L W T
authors.initials: LWT
authors.lastname: Boel
authors.affiliation: Hip and Knee Arthroplasty, Northern Orthopaedic Division, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: M B
authors.initials: MB
authors.lastname: Laursen
authors.affiliation: Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Stengaard-Pedersen
authors.affiliation: Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: K K
authors.initials: KK
authors.lastname: Keller
authors.affiliation: Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: ellhau@rm.dk.
authors.forename: E-M
authors.initials: EM
authors.lastname: Hauge
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D016723:Bone Remodeling; D002358:Cartilage, Articular / Q000473:pathology*; D016022:Case-Control Studies; D005270:Femur Head / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D009929:Organ Size; D015207:Osteoarthritis, Hip / Q000473:pathology* / Q000601:surgery
keywords: Bone turnover; Cartilage alterations; Femoral head; Osteoarthritis; Subchondral cortical bone; Subchondral trabecular bone