title: Impaired rib bone mass and quality in end-stage cystic fibrosis patients.
abstract: Advancements in research and clinical care have considerably extended the life expectancy of cystic fibrosis (CF) patients. However, with this extended survival come comorbidities. One of the leading co-morbidities is CF-related bone disease (CFBD), which progresses with disease severity and places patients at high risk for fractures, particularly of the ribs and vertebrae. Evidence that CF patients with vertebral fractures had higher bone mineral density (BMD) than the nonfracture group led us to postulate that bone quality is impaired in these patients. We therefore examined rib specimens resected at the time of lung transplant in CF patients to measure parameters of bone quantity and quality.
  
  
  
  In this exploratory study, we analysed 19 end-stage CF and 13 control rib specimens resected from otherwise healthy lung donors. BMD, bone microarchitecture, static parameters of bone formation and resorption and microcrack density of rib specimens were quantified by imaging, histomorphometric and histological methods. Variables reflecting the mineralization of ribs were assessed by digitized microradiography. The degree of bone mineralization (g/cm3) and the heterogeneity index of the mineralization (g/cm3) were calculated for trabecular and cortical bone.
  
  
  
  Compared to controls, CF ribs exhibited lower areal and trabecular volumetric BMD, decreased trabecular thickness and osteoid parameters, and increased microcrack density, that was particularly pronounced in specimens from patients with CF-related diabetes. Static parameters of bone resorption were similar in both groups. Degree of mineralization of total bone, but not heterogeneity index, was increased in CF specimens.
  
  
  
  The combination of reduced bone mass, altered microarchitecture, imbalanced bone remodeling (maintained bone resorption but decreased formation), increased microdamage and a small increase of the degree of mineralization, may lead to decreased bone strength, which, when coupled with chronic coughing and chest physical therapy, may provide an explanation for the increased incidence of rib fractures previously reported in this population.
authors.affiliation: Research Centre, CHU Sainte-Justine, 3175 Cote Sainte-Catherine Rd, Montreal, Québec H3T 1C5, Canada; Department of Nutrition, Faculty of Medicine, Université de Montreal, 2405 Cote Sainte-Catherine Rd, Montreal, Québec H3T 1A8, Canada. Electronic address: genevieve.mailhot@umontreal.ca.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Mailhot
authors.affiliation: Department of Pathology, Centre Hospitalier de l'Université de Montréal, 1058 St-Denis Street, Montreal, Québec H2X 3J4, Canada. Electronic address: natalie.dion.chum@ssss.gouv.qc.ca.
authors.forename: Natalie
authors.initials: N
authors.lastname: Dion
authors.affiliation: INSERM, UMR 1033, Univ Lyon, Université Claude Bernard Lyon 1, F69008 Lyon, France. Electronic address: delphine.farlay@inserm.fr.
authors.forename: Delphine
authors.initials: D
authors.lastname: Farlay
authors.affiliation: INSERM, UMR 1033, Univ Lyon, Université Claude Bernard Lyon 1, F69008 Lyon, France. Electronic address: sebastien.rizzo@inserm.fr.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Rizzo
authors.affiliation: Research Center, Centre Hospitalier de l'Université de Montréal, 1058 St-Denis Street, Montreal, Québec H2X 3J4, Canada; Department of Radiology, Faculty of Medicine, Université de Montreal, 2900, Boulevard Édouard-Montpetit, Montréal, Québec H3T 1J4, Canada. Electronic address: nathalie.bureau@umontreal.ca.
authors.forename: Nathalie J
authors.initials: NJ
authors.lastname: Bureau
authors.affiliation: Lung transplant Program, Centre Hospitalier de l'Université de Montréal, 1560 Sherbrooke East Street, Montreal, Québec H2L 4M1, Canada. Electronic address: valerie.jomphe.chum@ssss.gouv.qc.ca.
authors.forename: Valérie
authors.initials: V
authors.lastname: Jomphe
authors.affiliation: Research Centre, CHU Sainte-Justine, 3175 Cote Sainte-Catherine Rd, Montreal, Québec H3T 1C5, Canada. Electronic address: sosankhe@gmail.com.
authors.forename: Safiétou
authors.initials: S
authors.lastname: Sankhe
authors.affiliation: INSERM, UMR 1033, Univ Lyon, Université Claude Bernard Lyon 1, F69008 Lyon, France. Electronic address: georges.boivin@univ-lyon1.fr.
authors.forename: Georges
authors.initials: G
authors.lastname: Boivin
authors.affiliation: Department of Pediatrics, Montreal Children's Hospital-McGill University Health Centre, Meakins Christie Laboratories, Research Institute of the McGill University Health Centre, 1001 Décarie Boulevard, Montreal, Québec H4A 3J1, Canada; Respiratory Medicine, Centre Hospitalier de l'Universite de Montreal, 1560 Sherbrooke East Street, Montreal, Québec H2L 4M1, Canada. Electronic address: larry.lands@mcgill.ca.
authors.forename: Larry C
authors.initials: LC
authors.lastname: Lands
authors.affiliation: Research Center, Centre Hospitalier de l'Université de Montréal, 1058 St-Denis Street, Montreal, Québec H2X 3J4, Canada; Lung transplant Program, Centre Hospitalier de l'Université de Montréal, 1560 Sherbrooke East Street, Montreal, Québec H2L 4M1, Canada; Division of Thoracic Surgery, Department of Surgery, Centre Hospitalier de l'Université de Montréal, 1058 St-Denis Street, Montreal, Québec H2X 3J4, Canada. Electronic address: pasquale.ferraro@umontreal.ca.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Ferraro
authors.affiliation: Department of Medicine, Centre Hospitalier de l'Université de Montréal, 1058 St-Denis Street, Montreal, Québec H2X 3J4, Canada. Electronic address: lg.ste-marie@umontreal.ca.
authors.forename: Louis-Georges
authors.initials: LG
authors.lastname: Ste-Marie
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density; D016723:Bone Remodeling; D003550:Cystic Fibrosis / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D012272:Ribs / Q000473:pathology*; D055815:Young Adult
keywords: Bone quality; Cystic fibrosis; Histomorphometry; Lung transplant; Microcrack; Microradiography; Ribs