title: Analysis of bone matrix composition and trabecular microarchitecture of the femoral metaphysis in patients with osteonecrosis of the femoral head.
abstract: Osteonecrosis of the femoral head (ONFH) usually affects young individuals. In advanced stages of ONFH, total hip replacement is the golden standard. However, survivorship after total hip replacement has been reported to be poorer in patients with ONFH compared to patients with primary osteoarthritis (OA). In radiological and histological studies, an impaired bone quality was found not only for the femoral head, but also for the intertrochanteric and metaphyseal region. We hypothesize that alterations of bone quality in the femoral metaphysis might contribute to early stem loosening. The objective of this study was to assess the gene expression levels of factors regulating bone formation and remodeling of the intertrochanteric regions and the proximal femoral canal in patients with ONFH and those with primary OA. The cellular and macromolecular composition of the bone matrix was assessed by osteocalcin immunohistochemistry, and the three-dimensional organization of trabecular bone was characterized by microCT analysis. Gene expression of BMP-2 is twofold higher in the proximal femur in the region of the greater trochanter of patients with ONFH compared to those with OA. The number of osteoblasts in the greater trochanter of patients with ONFH (253/mm(2)) is increased compared to patients with OA (156/mm(2)). Trabecular properties in ONFH bone are altered for bone volume (OA: 32 mm(3), ONFH: 51 mm(3)) and structure model index (OA: 2.2, ONFH: 1.6) in the proximal femoral canal, but not in the trochanteric regions. These alterations in bone metabolism and architecture might contribute to the higher rates of stem loosening after total hip replacement in patients with ONFH, however, further experimental and clinical studies are needed to support our findings.
authors.affiliation: Department of Orthopaedic Surgery, University of Regensburg, ZMB/BioPark, Regensburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Tingart
authors.forename: Johannes
authors.initials: J
authors.lastname: Beckmann
authors.forename: Alfred
authors.initials: A
authors.lastname: Opolka
authors.forename: Maiko
authors.initials: M
authors.lastname: Matsuura
authors.forename: Jens
authors.initials: J
authors.lastname: Schaumburger
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.forename: Susanne
authors.initials: S
authors.lastname: Grässel
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics; D016723:Bone Remodeling / Q000502:physiology*; D002452:Cell Count; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology / Q000502:physiology; D005271:Femur Head Necrosis / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology; D015675:Osteocalcin / Q000378:metabolism; D011475:Prosthesis Failure; D011859:Radiography
chemical_list: C525718:BMP2 protein, human; C525819:BMP7 protein, human; D055396:Bone Morphogenetic Protein 2; D055419:Bone Morphogenetic Protein 7; D050659:Core Binding Factor Alpha 1 Subunit; C493709:RUNX2 protein, human; D015675:Osteocalcin